Change search
Link to record
Permanent link

Direct link
BETA
Garcia Carrasco, AlvaroORCID iD iconorcid.org/0000-0001-5603-8559
Publications (10 of 15) Show all publications
Ström, P., Petersson, P., Rubel, M., Bergsåker, H., Bykov, I., Frassinetti, L., . . . et al., . (2019). Analysis of deposited layers with deuterium and impurity elements on samples from the divertor of JET with ITER-like wall. Journal of Nuclear Materials, 516, 202-213
Open this publication in new window or tab >>Analysis of deposited layers with deuterium and impurity elements on samples from the divertor of JET with ITER-like wall
Show others...
2019 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 516, p. 202-213Article in journal (Refereed) Published
Abstract [en]

Inconel-600 blocks and stainless steel covers for quartz microbalance crystals from remote corners in the JET-ILW divertor were studied with time-of-flight elastic recoil detection analysis and nuclear reaction analysis to obtain information about the areal densities and depth profiles of elements present in deposited material layers. Surface morphology and the composition of dust particles were examined with scanning electron microscopy and energy-dispersive X-ray spectroscopy. The analyzed components were present in JET during three ITER-like wall campaigns between 2010 and 2017. Deposited layers had a stratified structure, primarily made up of beryllium, carbon and oxygen with varying atomic fractions of deuterium, up to more than 20%. The range of carbon transport from the ribs of the divertor carrier was limited to a few centimeters, and carbon/deuterium co-deposition was indicated on the Inconel blocks. High atomic fractions of deuterium were also found in almost carbon-free layers on the quartz microbalance covers. Layer thicknesses up to more than 1 micrometer were indicated, but typical values were on the order of a few hundred nanometers. Chromium, iron and nickel fractions were less than or around 1% at layer surfaces while increasing close to the layer-substrate interface. The tungsten fraction depended on the proximity of the plasma strike point to the divertor corners. Particles of tungsten, molybdenum and copper with sizes less than or around 1 micrometer were found. Nitrogen, argon and neon were present after plasma edge cooling and disruption mitigation. Oxygen-18 was found on component surfaces after injection, indicating in-vessel oxidation. Compensation of elastic recoil detection data for detection efficiency and ion-induced release of deuterium during the measurement gave quantitative agreement with nuclear reaction analysis, which strengthens the validity of the results.

Keywords
Fusion, Tokamak, Plasma-wall interactions, ToF-ERDA, NRA, SEM
National Category
Fusion, Plasma and Space Physics
Research subject
Physics
Identifiers
urn:nbn:se:kth:diva-240616 (URN)10.1016/j.jnucmat.2018.11.027 (DOI)000458897100020 ()2-s2.0-85060313456 (Scopus ID)
Note

QC 20190125

Available from: 2018-12-20 Created: 2018-12-20 Last updated: 2019-10-29Bibliographically approved
Trier, E., Frassinetti, L., Fridström, R., Garcia Carrasco, A., Hellsten, T., Johnson, T., . . . Zuin, M. (2019). ELM-induced cold pulse propagation in ASDEX Upgrade. Plasma Physics and Controlled Fusion, 61(4), Article ID 045003.
Open this publication in new window or tab >>ELM-induced cold pulse propagation in ASDEX Upgrade
Show others...
2019 (English)In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 61, no 4, article id 045003Article in journal (Refereed) Published
Abstract [en]

In ASDEX Upgrade, the propagation of cold pulses induced by type-I edge localized modes (ELMs) is studied using electron cyclotron emission measurements, in a dataset of plasmas with moderate triangularity. It is found that the edge safety factor or the plasma current are the main determining parameters for the inward penetration of the T-e perturbations. With increasing plasma current the ELM penetration is more shallow in spite of the stronger ELMs. Estimates of the heat pulse diffusivity show that the corresponding transport is too large to be representative of the inter-ELM phase. Ergodization of the plasma edge during ELMs is a possible explanation for the observed properties of the cold pulse propagation, which is qualitatively consistent with non-linear magneto-hydro-dynamic simulations.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2019
Keywords
ELMs, MHD instabilities, stochastic field, magnetic islands, cold pulse
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-245121 (URN)10.1088/1361-6587/aaf9c3 (DOI)000458986000002 ()
Note

QC 20190315

Available from: 2019-03-15 Created: 2019-03-15 Last updated: 2019-05-20Bibliographically approved
Meyer, H., Frassinetti, L., Garcia Carrasco, A., Ratynskaia, S. V., Rubel, M., Thorén, E., . . . et al., . (2019). Overview of physics studies on ASDEX Upgrade. Nuclear Fusion, 59(11), Article ID 112014.
Open this publication in new window or tab >>Overview of physics studies on ASDEX Upgrade
Show others...
2019 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 59, no 11, article id 112014Article in journal (Refereed) Published
Abstract [en]

The ASDEX Upgrade (AUG) programme, jointly run with the EUROfusion MST1 task force, continues to significantly enhance the physics base of ITER and DEMO. Here, the full tungsten wall is a key asset for extrapolating to future devices. The high overall heating power, flexible heating mix and comprehensive diagnostic set allows studies ranging from mimicking the scrape-off-layer and divertor conditions of ITER and DEMO at high density to fully non-inductive operation (q(95) = 5.5, beta(N) <= 2.8) at low density. Higher installed electron cyclotron resonance heating power <= 6 MW, new diagnostics and improved analysis techniques have further enhanced the capabilities of AUG. Stable high-density H-modes with P-sep/R <= 11 MW m(-1) with fully detached strike-points have been demonstrated. The ballooning instability close to the separatrix has been identified as a potential cause leading to the H-mode density limit and is also found to play an important role for the access to small edge-localized modes (ELMs). Density limit disruptions have been successfully avoided using a path-oriented approach to disruption handling and progress has been made in understanding the dissipation and avoidance of runaway electron beams. ELM suppression with resonant magnetic perturbations is now routinely achieved reaching transiently H-H98(y,H-2) <= 1.1. This gives new insight into the field penetration physics, in particular with respect to plasma flows. Modelling agrees well with plasma response measurements and a helically localised ballooning structure observed prior to the ELM is evidence for the changed edge stability due to the magnetic perturbations. The impact of 3D perturbations on heat load patterns and fast-ion losses have been further elaborated. Progress has also been made in understanding the ELM cycle itself. Here, new fast measurements of T-i and E-r allow for inter ELM transport analysis confirming that E-r is dominated by the diamagnetic term even for fast timescales. New analysis techniques allow detailed comparison of the ELM crash and are in good agreement with nonlinear MHD modelling. The observation of accelerated ions during the ELM crash can be seen as evidence for the reconnection during the ELM. As type-I ELMs (even mitigated) are likely not a viable operational regime in DEMO studies of 'natural' no ELM regimes have been extended. Stable I-modes up to n/n(GW) <= 0.7 have been characterised using beta-feedback. Core physics has been advanced by more detailed characterisation of the turbulence with new measurements such as the eddy tilt angle-measured for the first time-or the cross-phase angle of T-e and n(e) fluctuations. These new data put strong constraints on gyro-kinetic turbulence modelling. In addition, carefully executed studies in different main species (H, D and He) and with different heating mixes highlight the importance of the collisional energy exchange for interpreting energy confinement. A new regime with a hollow T-e profile now gives access to regimes mimicking aspects of burning plasma conditions and lead to nonlinear interactions of energetic particle modes despite the sub-Alfvenic beam energy. This will help to validate the fast-ion codes for predicting ITER and DEMO.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2019
Keywords
nuclear fusion, magnetic confinement, tokamak physics, ITER, DEMO
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-263334 (URN)10.1088/1741-4326/ab18b8 (DOI)000490603100002 ()2-s2.0-85072124840 (Scopus ID)
Note

QC 20191106

Available from: 2019-11-06 Created: 2019-11-06 Last updated: 2019-11-06Bibliographically approved
Joffrin, E., Bergsåker, H., Bykov, I., Frassinetti, L., Fridström, R., Garcia Carrasco, A., . . . et al., . (2019). Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall. Nuclear Fusion, 59(11), Article ID 112021.
Open this publication in new window or tab >>Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall
Show others...
2019 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 59, no 11, article id 112021Article in journal (Refereed) Published
Abstract [en]

For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des. 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D-T mixtures since 1997 and the first ever D-T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D-T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D-T preparation. This intense preparation includes the review of the physics basis for the D-T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D-T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfven eigenmode antennas, neutral gauges, radiation hard imaging systems...) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D-T campaign provides an incomparable source of information and a basis for the future D-T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2019
Keywords
fusion power, JET, tritium, isotope
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-260157 (URN)10.1088/1741-4326/ab2276 (DOI)000484122200001 ()2-s2.0-85070875113 (Scopus ID)
Note

QC 20190926

Available from: 2019-09-26 Created: 2019-09-26 Last updated: 2019-10-04Bibliographically approved
Garzotti, L., Frassinetti, L., Stefániková, E., Bergsåker, H., Bykov, I., Garcia Carrasco, A., . . . Zychor, I. (2019). Scenario development for D-T operation at JET. Nuclear Fusion, 59(7), Article ID 076037.
Open this publication in new window or tab >>Scenario development for D-T operation at JET
Show others...
2019 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 59, no 7, article id 076037Article in journal (Refereed) Published
Abstract [en]

The JET exploitation plan foresees D-T operations in 2020 (DTE2). With respect to the first D-T campaign in 1997 (DTE1), when JET was equipped with a carbon wall, the experiments will be conducted in presence of a beryllium-tungsten ITER-like wall and will benefit from an extended and improved set of diagnostics and higher additional heating power (32 MW neutral beam injection + 8 MW ion cyclotron resonance heating). There are several challenges presented by operations with the new wall: a general deterioration of the pedestal confinement; the risk of heavy impurity accumulation in the core, which, if not controlled, can cause the radiative collapse of the discharge; the requirement to protect the divertor from excessive heat loads, which may damage it permanently. Therefore, an intense activity of scenario development has been undertaken at JET during the last three years to overcome these difficulties and prepare the plasmas needed to demonstrate stationary high fusion performance and clear alpha particle effects. The paper describes the status and main achievements of this scenario development activity, both from an operational and plasma physics point of view.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2019
Keywords
tokamaks, magnetic confinement fusion, nuclear fusion power
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-262997 (URN)10.1088/1741-4326/ab1cca (DOI)000471317000001 ()2-s2.0-85069038696 (Scopus ID)
Note

QC 20191025

Available from: 2019-10-25 Created: 2019-10-25 Last updated: 2019-10-25Bibliographically approved
Tierens, W., Frassinetti, L., Hellsten, T., Petersson, P., Fridström, R., Garcia Carrasco, A., . . . et al., . (2019). Validation of the ICRF antenna coupling code RAPLICASOL against TOPICA and experiments. Nuclear Fusion, 59(4), Article ID 046001.
Open this publication in new window or tab >>Validation of the ICRF antenna coupling code RAPLICASOL against TOPICA and experiments
Show others...
2019 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 59, no 4, article id 046001Article in journal (Refereed) Published
Abstract [en]

In this paper we validate the finite element code RAPLICASOL, which models radiofrequency wave propagation in edge plasmas near ICRF antennas, against calculations with the TOPICA code. We compare the output of both codes for the ASDEX Upgrade 2-strap antenna, and for a 4-strap WEST-like antenna. Although RAPLICASOL requires considerably fewer computational resources than TOPICA, we find that the predicted quantities of experimental interest (including reflection coefficients, coupling resistances, S- and Z-matrix entries, optimal matching settings, and even radiofrequency electric fields) are in good agreement provided we are careful to use the same geometry in both codes.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2019
Keywords
ICRF, finite elements, simulation
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-243928 (URN)10.1088/1741-4326/aaf455 (DOI)000456197200001 ()
Note

QC 20190212

Available from: 2019-02-12 Created: 2019-02-12 Last updated: 2019-02-12Bibliographically approved
Vizvary, Z., Bourdel, B., Garcia Carrasco, A., Lam, N., Leipold, F., Pitts, R. A., . . . Widdowson, A. (2017). Engineering design and analysis of an ITER-like first mirror test assembly on JET. Paper presented at 29th Symposium on Fusion Technology (SOFT), SEP 05-09, 2016, Prague, CZECH REPUBLIC. Fusion engineering and design, 123, 1054-1057
Open this publication in new window or tab >>Engineering design and analysis of an ITER-like first mirror test assembly on JET
Show others...
2017 (English)In: Fusion engineering and design, ISSN 0920-3796, E-ISSN 1873-7196, Vol. 123, p. 1054-1057Article in journal (Refereed) Published
Abstract [en]

The ITER first mirrors are the components of optical diagnostic systems closest to the plasma. Deposition may build up on the surfaces of the mirror affecting their ability to fulfil their function. However, physics modelling of this layer growth is fraught with uncertainty. A new experiment is underway on JET, under contract to ITER, with primary objective to test if, under realistic plasma and wall material conditions and with ITER-like first mirror aperture geometry, deposits do grow on first mirrors. This paper describes the engineering design and analysis of this mirror test assembly. The assembly was installed in the 2014-15 shutdown and will be removed in the 2016-17 shutdown.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2017
Keywords
ITER-like first mirror, JET, Additive manufacturing, Remote handling, Disruption loads
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-221891 (URN)10.1016/j.fusengdes.2016.12.016 (DOI)000418992000221 ()
Conference
29th Symposium on Fusion Technology (SOFT), SEP 05-09, 2016, Prague, CZECH REPUBLIC
Note

QC 20180131

Available from: 2018-01-31 Created: 2018-01-31 Last updated: 2018-01-31Bibliographically approved
Garcia Carrasco, A., Petersson, P., Schwarz-Selinger, T., Wauters, T., Douai, D., Bobkov, V., . . . Rubel, M. (2017). Investigation of probe surfaces after ion cyclotron wall conditioning in ASDEX upgrade. NUCLEAR MATERIALS AND ENERGY, 12, 733-735
Open this publication in new window or tab >>Investigation of probe surfaces after ion cyclotron wall conditioning in ASDEX upgrade
Show others...
2017 (English)In: NUCLEAR MATERIALS AND ENERGY, ISSN 2352-1791, Vol. 12, p. 733-735Article in journal (Refereed) Published
Abstract [en]

For the first time, material analysis techniques have been applied to study the effect of ion cyclotron wall conditioning (ICWC) on probe surfaces in a metal-wall machine. ICWC is a technique envisaged to contribute to the removal of fuel and impurities from the first wall of ITER. The objective of this work was to assess impurity migration under ICWC operation. Tungsten probes were exposed in ASDEX Upgrade to discharges in helium. After wall conditioning, the probes were covered with a co-deposited layer containing D, B, C, N, O and relatively high amount of He. The concentration ratio He/C+B was 0.7. The formation of the co-deposited layer indicates that a fraction of the impurities desorbed from the wall under ICWC operation are transported by plasma and deposited away from their original location.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-220646 (URN)10.1016/j.nme.2016.12.018 (DOI)000417293300119 ()2-s2.0-85017170041 (Scopus ID)
Note

QC 20180111

Available from: 2018-01-11 Created: 2018-01-11 Last updated: 2018-01-11Bibliographically approved
Rubel, M., Moon, S., Petersson, P., Garcia Carrasco, A., Hallén, A., Krawczynska, A., . . . Widdowson, A. (2017). Metallic mirrors for plasma diagnosis in current and future reactors: tests for ITER and DEMO. Paper presented at 16th International Conference on Plasma-Facing Materials and Components for Fusion Applications (PFMC), MAY, 2017, GERMANY. Physica Scripta, T170, Article ID 014061.
Open this publication in new window or tab >>Metallic mirrors for plasma diagnosis in current and future reactors: tests for ITER and DEMO
Show others...
2017 (English)In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T170, article id 014061Article in journal (Refereed) Published
Abstract [en]

Optical spectroscopy and imaging diagnostics in next-step fusion devices will rely on metallic mirrors. The performance of mirrors is studied in present-day tokamaks and in laboratory systems. This work deals with comprehensive tests of mirrors: (a) exposed in JET with the ITER-like wall (JET-ILW); (b) irradiated by hydrogen, helium and heavy ions to simulate transmutation effects and damage which may be induced by neutrons under reactor conditions. The emphasis has been on surface modification: deposited layers on JET mirrors from the divertor and on near-surface damage in ion-irradiated targets. Analyses performed with ion beams, microscopy and spectro-photometry techniques have revealed: (i) the formation of multiple co-deposited layers; (ii) flaking-off of the layers already in the tokamak, despite the small thickness (130-200 nm) of the granular deposits; (iii) deposition of dust particles (0.2-5 mu m, 300-400 mm(-2)) composed mainly of tungsten and nickel; (iv) that the stepwise irradiation of up to 30 dpa by heavy ions (Mo, Zr or Nb) caused only small changes in the optical performance, in some cases even improving reflectivity due to the removal of the surface oxide layer; (v) significant reflectivity degradation related to bubble formation caused by the irradiation with He and H ions.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-220611 (URN)10.1088/1402-4896/aa8e27 (DOI)000417694700006 ()
Conference
16th International Conference on Plasma-Facing Materials and Components for Fusion Applications (PFMC), MAY, 2017, GERMANY
Note

QC 20180112

Available from: 2018-01-12 Created: 2018-01-12 Last updated: 2018-03-12Bibliographically approved
Garcia Carrasco, A., Petersson, P., Rubel, M., Widdowson, A., Fortuna-Zalesna, E., Jachmich, S., . . . Marot, L. (2017). Plasma impact on diagnostic mirrors in JET. NUCLEAR MATERIALS AND ENERGY, 12, 506-512
Open this publication in new window or tab >>Plasma impact on diagnostic mirrors in JET
Show others...
2017 (English)In: NUCLEAR MATERIALS AND ENERGY, ISSN 2352-1791, Vol. 12, p. 506-512Article in journal (Refereed) Published
Abstract [en]

Metallic mirrors will be essential components of all optical systems for plasma diagnosis in ITER. This contribution provides a comprehensive account on plasma impact on diagnostic mirrors in JET with the ITER-Like Wall. Specimens from the First Mirror Test and the lithium-beam diagnostic have been studied by spectrophotometry, ion beam analysis and electron microscopy. Test mirrors made of molybdenum were retrieved from the main chamber and the divertor after exposure to the 2013-2014 experimental campaign. In the main chamber, only mirrors located at the entrance of the carrier lost reflectivity (Be deposition), while those located deeper in the carrier were only slightly affected. The performance of mirrors in the JET divertor was strongly degraded by deposition of beryllium, tungsten and other species. Mirrors from the lithium-beam diagnostic have been studied for the first time. Gold coatings were severely damaged by intense arcing. As a consequence, material mixing of the gold layer with the stainless steel substrate occurred. Total reflectivity dropped from over 90% to less than 60%, i.e. to the level typical for stainless steel.

National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-220637 (URN)10.1016/j.nme.2016.12.032 (DOI)000417293300079 ()2-s2.0-85012926879 (Scopus ID)
Note

QC 20180111

Available from: 2018-01-11 Created: 2018-01-11 Last updated: 2018-03-12Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5603-8559

Search in DiVA

Show all publications