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  • 151. Esser, H. G.
    et al.
    Philipps, V.
    Freisinger, M.
    Widdowson, A.
    Heinola, K.
    Kirschner, A.
    Moeller, S.
    Petersson, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Brezinsek, S.
    Huber, A.
    Matthews, G. F.
    Rubel, Marek
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Sergienko, G.
    Material deposition on inner divertor quartz-micro balances during ITER-like wall operation in JET2015Inngår i: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 463, s. 796-799Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The migration of beryllium, tungsten and carbon to remote areas of the inner JET-ILW divertor and the accompanying co-deposition of deuterium has been investigated using post-mortem analysis of the housings of quartz-micro balances (QMBs) and their quartz crystals. The analysis of the deposition provides that the rate of beryllium atoms is significantly reduced compared to the analogue deposition rate of carbon during the carbon wall conditions (JET-C) at the same locations of the QMBs. A reduction factor of 50 was found at the entrance gap to the cryo-pumps while it was 14 under tile 5, the semi-horizontal target plate. The deposits consist of C/Be atomic ratios of typically 0.1-0.5 showing an enrichment of carbon in remote areas compared to directly exposed areas with less carbon. The deuterium retention fraction D/Be is between 0.3 and 1 at these unheated locations in the divertor.

  • 152. Faghihi, M.
    et al.
    Scheffel, Jan
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Stability of Small Axial Wavelength Internal Kink Modes of an Anisotropic Plasma1987Rapport (Annet vitenskapelig)
  • 153. Faghihi, M.
    et al.
    Scheffel, Jan
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Stability of Small Axial Wavelength Internal Kink Modes of an Anisotropic Plasma1987Inngår i: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 38, s. 495-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The double adiabatic equations are used to study the stability of a cylindrical Z-pinch with respect to small axial wavelength, internal kink (m ≥ 1) modes. It is found that marginally (ideally) unstable, isotropic equilibria are stabilized. Also, constant-current-density equilibria can be stabilized for P⊥ > P∥ and large β⊥

  • 154. Faghihi, M.
    et al.
    Scheffel, Jan
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Stability of Small Axial Wavelength Internal Kink Modes of an Anisotropic Plasma: Corrigendum1988Inngår i: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 40, s. 603-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A minor correction, having no major influence on our results, is reported here.

  • 155. Falchetto, G. L.
    et al.
    Coster, D.
    Coelho, R.
    Scott, B. D.
    Figini, L.
    Kalupin, D.
    Nardon, E.
    Nowak, S.
    Alves, L. L.
    Artaud, J. F.
    Basiuk, V.
    Bizarro, Jao P. S.
    Boulbe, C.
    Dinklage, A.
    Farina, D.
    Faugeras, B.
    Ferreira, J.
    Figueiredo, A.
    Huynh, Ph
    Imbeaux, F.
    Ivanova-Stanik, I.
    Johnson, Thomas
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Klingshirn, H-J
    Konz, C.
    Kus, A.
    Marushchenko, N. B.
    Pereverzev, G.
    Owsiak, M.
    Poli, E.
    Peysson, Y.
    Reimer, R.
    Signoret, J.
    Sauter, O.
    Stankiewicz, R.
    Strand, P.
    Voitsekhovitch, I.
    Westerhof, E.
    Zok, T.
    Zwingmann, W.
    The European Integrated Tokamak Modelling (ITM) effort: achievements and first physics results2014Inngår i: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 54, nr 4, s. 043018-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A selection of achievements and first physics results are presented of the European Integrated Tokamak Modelling Task Force (EFDA ITM-TF) simulation framework, which aims to provide a standardized platform and an integrated modelling suite of validated numerical codes for the simulation and prediction of a complete plasma discharge of an arbitrary tokamak. The framework developed by the ITM-TF, based on a generic data structure including both simulated and experimental data, allows for the development of sophisticated integrated simulations (workflows) for physics application.The equilibrium reconstruction and linear magnetohydrodynamic (MHD) stability simulation chain was applied, in particular, to the analysis of the edgeMHDstability of ASDEX Upgrade type-I ELMy H-mode discharges and ITER hybrid scenario, demonstrating the stabilizing effect of an increased Shafranov shift on edge modes. Interpretive simulations of a JET hybrid discharge were performed with two electromagnetic turbulence codes within ITM infrastructure showing the signature of trapped-electron assisted ITG turbulence. A successful benchmark among five EC beam/ray-tracing codes was performed in the ITM framework for an ITER inductive scenario for different launching conditions from the equatorial and upper launcher, showing good agreement of the computed absorbed power and driven current. Selected achievements and scientific workflow applications targeting key modelling topics and physics problems are also presented, showing the current status of the ITM-TF modelling suite.

  • 156. Fortuna, E.
    et al.
    Rubel, Marek J.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Philipps, V.
    Kurzydlowski, K. J.
    Mertens, Ph.
    Miskiewicz, M.
    Pisarek, M.
    Van Oost, G.
    Zielinski, W.
    Properties of co-deposited layers on graphite high heat flux components at the TEXTOR tokamak2007Inngår i: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 367, nr B, s. 1507-1511Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of this work was to examine the structure, composition and properties of co-deposited films from the TEXTOR tokamak. Hydrogenated films formed on the toroidal belt pump limiter (ALT-II), and on the ICRF antenna grill were studied using a set of material analysis techniques. Plasma edge diagnostics were used to assess the parameters influencing the film formation during discharges auxiliary heated by ICRF. The essential results are summarized as follows: (i) the distribution of plasma impurities co-deposited in the films is non-uniform and (ii) the surface topography, crystallographic structure, fuel retention and composition (i.e., content of re-deposited plasma impurities) of the films show significant diversity depending on the location where they were formed. These differences are associated with the local geometry, the tokamak operation scenarios and the resulting plasma edge properties.

  • 157. Fortuna, E.
    et al.
    Rubel, Marek J.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Psoda, M.
    Andrzejczuk, M.
    Kurzydlowski, K. J.
    Miskiewicz, M.
    Philipps, V.
    Pospieszczyk, A.
    Sergienko, G.
    Spychalski, M.
    Zielinski, W.
    Plasma-induced damage of tungsten coatings on graphite limiters2007Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T128, s. 162-165Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Vaccum plasma sprayed tungsten coatings with an evaporated sandwich Re - W interlayer on graphite limiter blocks were studied after the experimental campaign in the TEXTOR tokamak. The coating morphology was modified by high-heat loads and co-deposition of species from the plasma. Co-deposits contained fuel species, carbon, boron and silicon. X-ray diffractometer phase analysis indicated the coexistence of metallic tungsten and its carbides (WC and W2C) and boride (W2B). In the Re - W layer the presence of carbon was detected in a several micrometres thick zone. In the overheated part of the limiter, the Re - W layer was transformed into a sigma phase.

  • 158. Fortuna-Zalesna, E.
    et al.
    Grzonka, J.
    Moon, Sunwoo
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Rubel, Marek
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Petersson, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Widdowson, A.
    Fine metal dust particles on the wall probes from JET-ILW2017Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T170, artikkel-id 014038Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Collection and ex situ studies of dust generated in controlled fusion devices during plasma operation are regularly carried out after experimental campaigns. Herewith results of the dust survey performed in JET after the second phase of operation with the metal ITER-like wall (2013-2014) are presented. For the first-time-ever particles deposited on silicon plates acting as dust collectors installed in the inner and outer divertor have been examined. The emphasis is on analysing metal particles (Be and W) with the aim to determine their composition, size and surface topography. The most important is the identification of beryllium dust in the form of droplets (both splashes and spherical particles), flakes of co-deposits and small fragments of Be tiles. Tungsten and nickel rich (from Inconel) particles are also identified. Nitrogen from plasma edge cooling has been detected in all types of particles. They are categorized and the origin of various constituents is discussed.

  • 159. Fortuna-Zalesna, E.
    et al.
    Grzonka, J.
    Rubel, Marek
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Garcia Carrasco, Alvaro
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Widdowson, A.
    Baron-Wiechec, A.
    Ciupinski, L.
    Studies of dust from JET with the ITER-Like Wall: Composition and internal structure2017Inngår i: NUCLEAR MATERIALS AND ENERGY, ISSN 2352-1791, Vol. 12, s. 582-587Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Results are presented for the dust survey performed at JET after the second experimental campaign with the ITER-Like Wall: 2013-2014. Samples were collected on adhesive stickers from several different positions in the divertor both on the tiles and on the divertor carrier. Brittle dust-forming deposits on test mirrors from the inner divertor wall were also studied. Comprehensive characterization accomplished by a wide range of high-resolution microscopy techniques, including focused ion beam, has led to the identification of several classes of particles: (i) beryllium flakes originating either from the Be coatings from the inner wall cladding or Be-rich mixed co-deposits resulting from material migration; (ii) beryllium droplets and splashes; (iii) tungsten and nickel-rich (from Inconel) droplets; (iv) mixed material layers with a various content of small (8-200 nm) W-Mo and Ni-based debris. A significant content of nitrogen from plasma edge cooling has been identified in all types of co-deposits. A comparison between particles collected after the first and second experimental campaign is also presented and discussed.

  • 160. Fortuna-Zalesna, E.
    et al.
    Weckmann, Armin
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Grozonka, J.
    Rubel, Marek
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Esser, H. G.
    Freisinger, M.
    Kreter, A.
    Kischner, A.
    Sergienko, G.
    Ström, Petter
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Dust Survey Following the Final Shutdown of TEXTOR: Metal Particles and Fuel Retention2016Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T167, artikkel-id 014059Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The work presents results of a broad TEXTOR dust survey in terms of its composition, structure, distribution and fuel content. The dust particles were collected after final shutdown of TEXTOR in December 2013. Fuel retention, as determined by thermal desorption, varied significantly, even by two orders of magnitude, dependent on the dust location in the machine. Dust structure was examined by means of scanning electron microscopy combined with energy-dispersive X-ray spectroscopy, focused ion beam and scanning transmission electron microscopy. Several categories of dust have been identified. Carbon-based stratified and granular deposits were dominating, but the emphasis in studies was on metal dust. They were found in the form of small particles, small spheres, flakes and splashes which formed “comet”-like structures clearly indicating directional effects in the impact on surfaces of plasma-facing components. Nickel-rich alloys from the Inconel liner and iron-based ones from various diagnostic holders were the main components of metal-containing dust, but also molybdenum and tungsten debris were detected. Their origin is discussed.

  • 161.
    Frassinetti, L.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Brunsell, Per R.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Drake, James R.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Menmuir, S.
    Cecconello, Marco
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Spontaneous quasi single helicity regimes in EXTRAP T2R reversed-field pinch2007Inngår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 14, nr 11Artikkel i tidsskrift (Fagfellevurdert)
  • 162.
    Frassinetti, Lorenzo
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Inter-ELM evolution of the pedestal structure in JET-ILW2016Inngår i: 24th European Fusion Physics Workshop, 28-30 November 2016, 2016Konferansepaper (Annet vitenskapelig)
  • 163.
    Frassinetti, Lorenzo
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Magnetic perturbation and dynamo generation effects on 3-d flows in RFPs2010Inngår i: 18th European Fusion Physics Workshop, December 2010, Mayrhofen, Austria, 2010Konferansepaper (Annet vitenskapelig)
  • 164.
    Frassinetti, Lorenzo
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Wall diffusion time in EXTRAP T2R and possible applications to tokamaks2012Konferansepaper (Annet vitenskapelig)
  • 165.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Alfier, A.
    Pasqualotto, R.
    Bonomo, F.
    Innocente, P.
    Heat diffusivity model and temperature simulations in RFX-mod2008Inngår i: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 48, nr 4, s. 045007-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The core transport properties of reversed field pinch (RFP) plasmas in the standard regime are generally associated with a high level of magnetic chaos. Indeed, in the RFX-mod RFP device, the core temperature profile is often very flat, indicating that the heat diffusivity is very high. In contrast, the temperature edge profile has a steep gradient, indicating that the edge is characterized by low heat transport. These simple experimental evidences are the basis of a heat diffusivity model that is used as an input to a numerical code for plasma temperature simulation. The simulated temperature reproduces with good accuracy both the experimental T, time evolution and its radial profiles in different plasma scenarios, showing that the model is useful for estimating the plasma heat diffusivity. This work suggests that the heat transport properties in the RFP plasma core are dominated by magnetic chaos in standard discharges and suggests a simple way to estimate electron heat diffusivity from density, input power and magnetic fluctuation measurements.

  • 166.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Beurskens, M
    ELM losses in high triangularity plasmas in JET with the metal and carbon wall2012Inngår i: EFDA-JET Science Meeting on ELM Studies, June 25, 2012, 2012Konferansepaper (Annet vitenskapelig)
  • 167.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Beurskens, M
    Study on global and pedestal confinement in metal and carbon wall2012Inngår i: EFDA-JET Science Meeting on Pedestal Studies, June 11, 2012, 2012Konferansepaper (Annet vitenskapelig)
  • 168.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Beurskens, M
    Alper, B
    Bourdelle, C
    Brezinsek, S
    Bucalossi, J
    Buratti, P
    Crisanti, C
    Challis, C
    Flanagan, J
    Giroud, C
    Groth, M
    Hobirk, J
    Joffrin, E
    Leyland, M
    Lomas, P
    Kampeenars, M
    Maslov, M
    Matthews, G
    Mayoral, M
    McCormick, K
    Neu, R
    Nunes, I
    Rimini, F
    Saarelma, S
    Core versus edge confinement in JET with the ILW compared to the CFC first-wall2012Inngår i: 39th EPS Conference on Plasma Physics 2012, EPS 2012 and the 16th International Congress on Plasma Physics, 2012, s. 1334-1337Konferansepaper (Fagfellevurdert)
  • 169.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Beurskens, M. N. A.
    Saarelma, S.
    Boom, J. E.
    Delabie, E.
    Flanagan, J.
    Kempenaars, M.
    Giroud, C.
    Lomas, P.
    Meneses, L.
    Maggi, C. S.
    Menmuir, S.
    Nunes, I.
    Rimini, F.
    Stefániková, Estera
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Urano, H.
    Verdoolaege, G.
    Global and pedestal confinement and pedestal structure in dimensionless collisionality scans of low-triangularity H-mode plasmas in JET-ILW2017Inngår i: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 57, nr 1, artikkel-id 061012Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A dimensionless collisionality scan in low-triangularity plasmas in the Joint European Torus with the ITER-like wall (JET-ILW) has been performed. The increase of the normalized energy confinement (defined as the ratio between thermal energy confinement and Bohm confinement time) with decreasing collisionality is observed. Moreover, at low collisionality, a confinement factor H-98, comparable to JET-C, is achieved. At high collisionality, the low normalized confinement is related to a degraded pedestal stability and a reduction in the density-profile peaking. The increase of normalized energy confinement is due to both an increase in the pedestal and in the core regions. The improvement in the pedestal is related to the increase of the stability. The improvement in the core is driven by (i) the core temperature increase via the temperature-profile stiffness and by (ii) the density-peaking increase driven by the low collisionality. Pedestal stability analysis performed with the ELITE (edge-localized instabilities in tokamak equilibria) code has a reasonable qualitative agreement with the experimental results. An improvement of the pedestal stability with decreasing collisionality is observed. The improvement is ascribed to the reduction of the pedestal width, the increase of the bootstrap current and the reduction of the relative shift between the positions of the pedestal density and pedestal temperature. The EPED1 model predictions for the pedestal pressure height are qualitatively well correlated with the experimental results. Quantitatively, EPED1 overestimates the experimental pressure by 15-35%. In terms of the pedestal width, a correct agreement (within 10-15%) between the EPED1 and the experimental width is found at low collisionality. The experimental pedestal width increases with collisionality. Nonetheless, an extrapolation to low-collisionality values suggests that the width predictions from the KBM constraint are reasonable for ITER.

  • 170.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Beurskens, M. N. A.
    Scannell, R.
    Osborne, T. H.
    Flanagan, J.
    Kempenaars, M.
    Maslov, M.
    Pasqualotto, R.
    Walsh, M.
    Spatial resolution of the JET Thomson scattering system2012Inngår i: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 83, nr 1, s. 013506-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The instrument function of the high resolution Thomson scattering (HRTS) diagnostic in the Joint European Torus (JET) has been calculated for use in improved pedestal profile analysis. The full width at half maximum (FWHM) of the spatial instrument response is (22 +/- 1) mm for the original HRTS system configuration and depends on the particular magnetic topology of the JET plasmas. An improvement to the optical design of the laser input system is presented. The spatial smearing across magnetic flux surfaces is reduced in this design. The new input system has been implemented (from JPN 78742, July 2009) and the HRTS instrument function corresponding to the new configuration has been improved to approximately FWHM = (9.8 +/- 0.8) mm. The reconstructed instrument kernels are used in combination with an ad hoc forward deconvolution procedure for pedestal analysis. This procedure produces good results for both the old and new setups, but the reliability of the deconvolved profiles is greatly reduced when the pedestal width is of the same order as, or less than the FWHM of the instrument kernel.

  • 171.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Beurskens, M
    Saarelma, S
    Global and pedestal confinement and pedestal structure in dimensionless collisionality scans of low triangularity H-mode plasmas in JET-ILW2015Inngår i: ITPA-PEP meeting, 22-23 October 2015, 2015Konferansepaper (Annet vitenskapelig)
  • 172.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Beurskens, M
    Saarelma, S.
    Boom, J. E.
    Delabie, E.
    Flanagan, J.
    Kempenaars, C. M.
    Giroud, G.
    Lomas, P.
    Meneses, L.
    Menmuir, S.
    Nunes, I.
    Rimini, F.
    Confinement and pedestal in dimensionless collisionality scans of low triangularity H-mode plasmas in JET-ILW2015Inngår i: 42nd European Physical Society Conference on Plasma Physics, EPS 2015, European Physical Society (EPS) , 2015Konferansepaper (Fagfellevurdert)
  • 173.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Beurskens, M.N.A.
    McDonald, D.C.
    Hobirk, J.
    Zarzoso, D.
    Buratti, P.
    Crisanti, F.
    Challis, C.
    Giovannozzi, E.
    Joffrin, E.
    Lomas, P.
    Lonnroth, J.
    Maggi, C.
    Nunes, I.
    Saarelma, S.
    Saibene, G.
    et al.,
    Pedestal confinement in hybrid versus baseline plasmas in JET2010Inngår i: 37th European Physical Society Conference on Plasma Physics. Contributed Papers, 2010, s. P1.1031-Konferansepaper (Fagfellevurdert)
  • 174.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Brunsell, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Cecconello, Marco
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Drake, James R.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Khan, Muhammad Waqas Mehmood
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Menmuir, Sheena
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Olofsson, Erik
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Active feedback control of QSH in EXTRAP-T2R2008Konferansepaper (Fagfellevurdert)
  • 175.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Brunsell, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Drake, James Robert
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Menmuir, Sheena
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Cecconello, Marco
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Spontaneous QSH in the EXTRAP T2R reversed-field pinch2007Inngår i: 34th EPS Conference on Plasma Physics 2007, EPS 2007 - Europhysics Conference Abstracts, 2007, s. 579-582Konferansepaper (Fagfellevurdert)
  • 176.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Brunsell, Per R.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Cecconello, Marco
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Drake, James R.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Heat transport modelling in EXTRAP T2R2009Inngår i: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 49, nr 2Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A model to estimate the heat transport in the EXTRAP T2R reversed field pinch (RFP) is described. The model, based on experimental and theoretical results, divides the RFP electron heat diffusivity chi(e) into three regions, one in the plasma core, where chi(e) is assumed to be determined by the tearing modes, one located around the reversal radius, where chi(e) is assumed not dependent on the magnetic fluctuations and one in the extreme edge, where high chi(e) is assumed. The absolute values of the core and of the reversal chi(e) are determined by simulating the electron temperature and the soft x-ray and by comparing the simulated signals with the experimental ones. The model is used to estimate the heat diffusivity and the energy confinement time during the flat top of standard plasmas, of deep F plasmas and of plasmas obtained with the intelligent shell.

  • 177.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Brunsell, Per R.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Drake, James R.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Experiments and modelling of active quasi-single helicity regime generation in a reversed field pinch2009Inngår i: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 49, nr 7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The interaction of a static resonant magnetic perturbation (RMP) with a tearing mode (TM) is becoming a relevant topic in fusion plasma physics. RMPs can be generated by active coils and then used to affect the properties of TMs and of the corresponding magnetic islands. This paper shows how the feedback system of the EXTRAP T2R reversed field pinch (RFP) can produce a RMP that affects a rotating TM and stimulate the transition to the so-called quasi-single helicity (QSH) regime, a RFP plasma state characterized by a magnetic island surrounded by low magnetic chaos. The application of the RMP can increase the QSH probability up to 10% and enlarge the size of the corresponding island. Part of the experimental results are supported by a theoretical study that models the effect of the active coils on the magnetic island.

  • 178.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Brunsell, Per R.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Drake, James R.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Heat transport in the quasi-single-helicity islands of EXTRAP T2R2009Inngår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 16, nr 3Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The heat transport inside the magnetic island generated in a quasi-single-helicity regime of a reversed-field pinch device is studied by using a numerical code that simulates the electron temperature and the soft x-ray emissivity. The heat diffusivity chi(e) inside the island is determined by matching the simulated signals with the experimental ones. Inside the island, chi(e) turns out to be from one to two orders of magnitude lower than the diffusivity in the surrounding plasma, where the magnetic field is stochastic. Furthermore, the heat transport properties inside the island are studied in correlation with the plasma current and with the amplitude of the magnetic fluctuations.

  • 179.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Brunsell, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Setiadi, C
    Fridström, Richard
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Khan, W
    Drake, J
    TM locking and unlocking mechanism to an external resonant field2014Inngår i: Meeting of the Nordic Research Units in EUROfusion, 2014Konferansepaper (Annet vitenskapelig)
  • 180.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Brunsell, P.R.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Fridström, R
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Setiadi, C
    Khan, W
    EXTEAP T2R overview2015Inngår i: 17th IEA/RFP Workshop, 26-29 october 2015, 2015Konferansepaper (Annet vitenskapelig)
  • 181.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Challis, C
    The role of the pedestal on the confinement in hybrids and baseline plasmas2014Inngår i: EUROfusion Science Meeting on Pedestal Studies, Sept 11, 2014, 2014Konferansepaper (Annet vitenskapelig)
  • 182.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Dodt, D.
    Beurskens, M. N. A.
    Sirinelli, A.
    Boom, J. E.
    Eich, T.
    Flanagan, J.
    Giroud, C.
    Jachmich, M. S.
    Kempenaars, M.
    Lomas, P.
    Maddison, G.
    Maggi, C.
    Neu, R.
    Nunes, I.
    von Thun, C. Perez
    Sieglin, B.
    Stamp, M.
    Effect of nitrogen seeding on the energy losses and on the time scales of the electron temperature and density collapse of type-I ELMs in JET with the ITER-like wall2015Inngår i: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 55, nr 2, artikkel-id 023007Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The baseline type-I ELMy H-mode scenario has been re-established in JET with the new tungsten MKII-HD divertor and beryllium on the main wall (hereafter called the ITER-like wall, JET-ILW). The first JET-ILW results show that the confinement is degraded by 20-30% in the baseline scenarios compared to the previous carbon wall JET (JET-C) plasmas. The degradation is mainly driven by the reduction in the pedestal temperature. Stored energies and pedestal temperature comparable to the JET-C have been obtained to date in JET-ILW baseline plasmas only in the high triangularity shape using N-2 seeding. This work compares the energy losses during ELMs and the corresponding time scales of the temperature and density collapse in JET-ILWbaseline plasmas with and without N-2 seeding with similar JET-C baseline plasmas. ELMs in the JET-ILW differ from those with the carbon wall both in terms of time scales and energy losses. The ELM time scale, defined as the time to reach the minimum pedestal temperature soon after the ELM collapse, is similar to 2ms in the JET-ILW and lower than 1 ms in the JET-C. The energy losses are in the range Delta W-ELM/W-ped approximate to 7-12% in the JET-ILWand Delta W-ELM/W-ped approximate to 10-20% in JET-C, and fit relatively well with earlier multi-machine empirical scalings of Delta W-ELM/W-ped with collisionality. The time scale of the ELM collapse seems to be related to the pedestal collisionality. Most of the non-seeded JET-ILW ELMs are followed by a further energy drop characterized by a slower time scale similar to 8-10 ms (hereafter called slow transport events), that can lead to losses in the range Delta W-slow/W-ped approximate to 15-22%, slightly larger than the losses in JET-C. The N-2 seeding in JET-ILW significantly affects the ELMs. The JET-ILW plasmas with N-2 seeding are characterized by ELM energy losses and time scales similar to the JET-C and by the absence of the slow transport events.

  • 183.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Dodt, D
    Beurskens, M
    Sirenelli, A
    Eich, T
    Flanagan, J
    Giroud, C
    Jachmich, S
    Kampenaars, M
    Lomas, P
    Maddison, M
    Neu, R
    Nunes, I
    Sieglin, B
    ELM energy losses in baseline plasma in JET with the ILW compared to the CFC first-wall2013Inngår i: 40th EPS Conference on Plasma Physics, EPS 2013: 40th EPS Conference on Plasma Physics, EPS 2013; Espoo; Finland; 1 July 2013 through 5 July 2013, 2013, , s. 4Konferansepaper (Fagfellevurdert)
  • 184.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Dunne, M
    Beurskens, M
    Wolfrum, E
    ELM dynamics in AUG and JET with & without Nitrogen seeding2014Inngår i: IPTA-PEP meeting, 2014, 2014Konferansepaper (Annet vitenskapelig)
  • 185.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Dunne, M
    Beurskens, M
    Wolfrum, E
    ELM energy losses in AUG with & without Nitrogen seeding2015Inngår i: 15th International Workshop on H-mode Physics and Transport Barriers, 19-21 October 2015, 2015Konferansepaper (Annet vitenskapelig)
  • 186.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Dunne, M. G.
    Beurskens, M.
    Wolfrum, E.
    Bogomolov, A.
    Carralero, D.
    Cavedon, M.
    Fischer, R.
    Laggner, F. M.
    McDermott, R. M.
    Meyer, H.
    Tardini, G.
    Viezzer, E.
    ELM behavior in ASDEX Upgrade with and without nitrogen seeding2017Inngår i: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 57, nr 2, artikkel-id 022004Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Type I ELM behavior in ASDEX Upgrade with full W plasma facing components is studied in terms of time scales and energy losses for a large set of shots characterized by similar operational parameters but different nitrogen seeding rate and input power. ELMs with no nitrogen can have two typical behaviors, that can be classified depending on their duration, the long and the short ELMs. The work shows that both short and long ELMs have a similar first phase, but the long ELMs are characterized by a second phase with further energy losses. The second phase disappears when nitrogen is seeded with a flux rate above 10(22) (e s(-1)). The phenomenon is compatible with a threshold effect. The presence of the second phase is related to a high divertor/scrape-off layer (SOL) temperature and/or to a low pedestal temperature. The ELM energy losses of the two phases are regulated by different mechanisms. The energy losses of the first phase increase with nitrogen which, in turn, produce the increase of the pedestal temperature. So the energy losses of the first phase are regulated by the pedestal top parameters and the increase with nitrogen is due to the decreasing pedestal collisionality. The energy losses of the second phase are related to the divertor/ SOL conditions. The long ELMs energy losses increase with increasing divertor temperature and with the number of the expelled filaments. In terms of the power lost by the plasma, the nitrogen seeding increases the power losses of the short ELMs. The long ELMs have a first phase with power losses comparable to the short ELMs losses. Assuming no major difference in the wetted area, these results suggest that (i) the nitrogen might increase the divertor heat fluxes during the short ELMs and that (ii) the long ELMs, despite the longer time scale, are not beneficial in terms of divertor heat loads.

  • 187.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Fridström, R
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Brunsell, P. R.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Experimental study on the physical mechanism related to the hysteresis  of the  TM locking‐unlocking process to an external  field in EXTRAP T2R2014Inngår i: 19th workshop on MHD stability control, 2014Konferansepaper (Annet vitenskapelig)
  • 188.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Fridström, R
    Brunsell, P. R.
    Khan, W
    Setiadi, C
    Experimental study on the physical mechanism related to the hysteresis of the  TM locking‐unlocking process to an external  field in EXTRAP T2R2015Inngår i: 17th IEA/RFP Workshop, 26-29 october 2015, 2015Konferansepaper (Annet vitenskapelig)
  • 189.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Fridström, R
    Sun, Y
    Sweeney, R
    Brunsell, P.R.
    Khan, W
    Setiadi, C
    Volpe, F
    Effects of external magnetic perturbations in EXRAP T2R2016Inngår i: 26th IAEA Fusion Energy Conference, 17-22 October 2016, 2016Konferansepaper (Fagfellevurdert)
  • 190.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Fridström, Richard
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Men, S
    Brunsell, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Tearing mode locking and unlocking to an error field in EXTRAP T2R2013Inngår i: 18th Workshop on MHD Stability Control: Santa Fe, New Mexico, USA, 18-20 November, 2013, 2013Konferansepaper (Annet vitenskapelig)
  • 191.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Fridström, Richard
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Menmuir, S
    Brunsell, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Braking torque due to external perturbations in EXTRAP T2R2013Inngår i: Joint 19th ISHW and 16th IEA-RFP workshop: Padova, Italy, 16-20 September, 2013, 2013Konferansepaper (Fagfellevurdert)
  • 192.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Fridström, Richard
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Menmuir, Sheena
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Brunsell, Per R.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    The tearing mode locking-unlocking mechanism to an external resonant field in EXTRAP T2R2014Inngår i: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 56, nr 10, s. 104001-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The tearing mode (TM) locking and unlocking process due to an external resonant magnetic perturbation (RMP) is experimentally studied in EXTRAP T2R. The RMP produces a reduction of the natural TM velocity and ultimately the TM locking if a threshold in the RMP amplitude is exceeded. During the braking process, the TM slows down via a mechanism composed of deceleration and acceleration phases. During the acceleration phases, the TM can reach velocities higher than the natural velocity. Once the TM locking occurs, the RMP must be reduced to a small amplitude to obtain the TM unlocking, showing that the unlocking threshold is significantly smaller than the locking threshold and that the process is characterized by hysteresis. Experimental results are in qualitative agreement with a model that describes the locking-unlocking process via the balance of the electromagnetic torque produced by the RMP that acts to brake the TM and the viscous torque that tends to re-establish the unperturbed velocity.

  • 193.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Fridström, Rickard
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Olofsson, Erik
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Setiadi, Agung Chris
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Brunsell, Per
    Volpe, Francesco
    Columbia University, New York, NY, USA.
    Drake, James
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    A Technique for the Estimation of the Wall Diffusion Time2012Inngår i: 54th Meeting of the APS Division of Plasma Physics, November 2012,  Providence, USA, 2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Feedback systems are important tools for an advanced control of the MHD instabilities in fusion plasmas, both for the suppression of undesired modes, such as RWMs, and for the generation of external perturbations for ELM suppression. A good knowledge of the diffusion time through the machine wall of each external harmonics is necessary for reaching optimal performances of the feedback algorithms.A correct theoretical estimation is not easy due the presence of three-dimensional mechanical structures in the devices, such as shell cuts and external conductive structures that need to be considered. Identification of differences in the vertical and horizontal diffusion time are not simple from a theoretical point of view.This work will present a relatively simple technique to experimentally estimate the diffusion time for each harmonic. The technique is based on the generation of rotating external magnetic perturbations in vacuum and on the quantification of the wall screening from the measured field inside the wall. The technique will be able to quantify possible differences among the horizontal and vertical diffusion time. In the final part of the work, the comparison with the results obtained with a closed-loop identification algorithm of the machine plant will be discussed.

  • 194.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Izzo, V.
    Olofsson, Erik
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Menmuir, Sheena
    Brunsell, Per R.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Drake, James Robert
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Screening effect of plasma flow on resonant magnetic perturbations in EXTRAP T2R2012Inngår i: EPS Conf. Plasma Phys., EPS Int. Congr. Plasma Phys., 2012, s. 365-368Konferansepaper (Fagfellevurdert)
  • 195.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Joffrin, E.
    Tamain, P.
    Maget, P.
    Saarelma, S.
    Boom, J. E.
    Flanagan, J.
    Giroud, C.
    Delabie, E.
    Kempenaars, M.
    Lomas, P.
    Maggi, C.
    Menes, L.
    Nunes, I.
    Effect of the divertor geometry on the pedestal confinement in JET-ILW2014Inngår i: 41st EPS Conference on Plasma Physics, EPS 2014, 2014Konferansepaper (Fagfellevurdert)
  • 196.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Maggi, C
    Dependence of pedestal structure and stability on beta and comparison with power/gas scans2016Inngår i: EUROfusion Science Meeting on Pedestal Studies, Sept 15, 2016, 2016Konferansepaper (Annet vitenskapelig)
  • 197.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Menmuir, Sheena
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Brunsell, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Resonant magnetic perturbation penetration and locking threshold in EXTRAP T2R2013Inngår i: 40th EPS Conference on Plasma Physics: Espoo, Finland, 1-5 July, 2013, 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In a tokamak or reversed field pinch plasma with rotating tearing modes (TM), the penetration of resonant magnetic perturbations (RMPs) and/or error-fields can lead to braking of the TM rotation velocity and eventually to wall locking of the TM. The TM rotation braking may occur via the electromagnetic torque that acts locally near the rational surface [1, 2, 3]. At a critical RMP amplitude, a transition from a fast rotating TM to a slowly rotating or wall locked TM occurs. This critical RMP amplitude is referred to as the error-field penetration threshold or the TM locking threshold. In this work, the threshold is experimentally studied in the EXTRAP T2R reversed-field pinch. The experimental results are compared with a model for the non-linear TM dynamics, which incorporates the balance between the electromagnetic braking torque and the viscous drag of the rotating plasma [3].

  • 198.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Menmuir, Sheena
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Khan, Waqas
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Olofsson, Erik
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Brunsell, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Drake, James Robert
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    The effect of external control fields on tearing mode dynamics2011Inngår i: Proceedings of the 38th European Physical Society Conference on Plasma Physics, 2011, s. 1220-1223Konferansepaper (Fagfellevurdert)
  • 199.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Menmuir, Sheena
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Olofsson, K. Erik J.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Brunsell, Per R.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Drake, James Robert
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Tearing mode velocity braking due to resonant magnetic perturbations2012Inngår i: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 52, nr 10, s. 103014-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of resonant magnetic perturbations (RMPs) on the tearing mode (TM) velocity is studied in EXTRAP T2R. Experimental results show that the RMP produces TM braking until a new steady velocity or wall locking is reached. The braking is initially localized at the TM resonance and then spreads to the other TMs and to the rest of the plasma producing a global velocity reduction via the viscous torque. The process has been used to experimentally estimate the kinematic viscosity profile, in the range 2-40 m 2 s -1, and the electromagnetic torque produced by the RMP, which is strongly localized at the TM resonance. Experimental results are then compared with a theoretical model which gives a reasonable qualitative explanation of the entire process.

  • 200.
    Frassinetti, Lorenzo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Olofsson, E
    Brunsell, P
    Menmuir, S
    Drake, J
    Screening Effect of Plasma Flow on RMP Penetration in EXTRAP T2R2011Inngår i: 53rd Meeting of the APS Division of Plasma Physics, November 2011,  Salt Lake City, USA, 2011Konferansepaper (Fagfellevurdert)
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