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Garcia Carrasco, AlvaroORCID iD iconorcid.org/0000-0001-5603-8559
Publications (10 of 11) Show all publications
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
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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
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
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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
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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
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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
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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
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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
Hakola, A., Brezinsek, S., Douai, D., Balden, M., Bobkov, V., Carralero, D., . . . Siketic, Z. (2017). Plasma-wall interaction studies in the full-W ASDEX upgrade during helium plasma discharges. Nuclear Fusion, 57(6), Article ID 066015.
Open this publication in new window or tab >>Plasma-wall interaction studies in the full-W ASDEX upgrade during helium plasma discharges
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2017 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 57, no 6, article id 066015Article in journal (Refereed) Published
Abstract [en]

Plasma-wall interactions have been studied in the full-W ASDEX Upgrade during its dedicated helium campaign. Relatively clean plasmas with a He content of > 80% could be obtained by applying ion cyclotron wall conditioning (ICWC) discharges upon changeover from D to He. However, co-deposited layers with significant amounts of He and D were measured on W samples exposed to ICWC plasmas at the low-field side (outer) midplane. This is a sign of local migration and accumulation of materials and residual fuel in regions shadowed from direct plasma exposure albeit globally D was removed from the vessel. When exposing W samples to ELMy H-mode helium plasmas in the outer strike-point region, no net erosion was observed but the surfaces had been covered with co-deposited layers mainly consisting of W, B, C, and D and being the thickest on rough and modified surfaces. This is different from the typical erosion-deposition patterns in D plasmas, where usually sharp net-erosion peaks surrounded by prominent net-deposition maxima for W are observed close to the strike point. Moreover, no clear signs of W nanostructure growth or destruction could be seen. The growth of deposited layers may impact the operation of future fusion reactors and is attributed to strong sources in the main chamber that under suitable conditions may switch the balance from net erosion into net deposition, even close to the strike points. In addition, the absence of noticeable chemical erosion in helium plasmas may have affected the thickness of the deposited layers. Retention of He, for its part, remained small and uniform throughout the strike-point region although our results indicate that samples with smooth surfaces can contain an order of magnitude less He than their rough counterparts.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2017
Keywords
plasma-wall interaction, helium, tungsten fuzz, erosion, retention
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-207649 (URN)10.1088/1741-4326/aa69c4 (DOI)000399878400002 ()2-s2.0-85019404002 (Scopus ID)
Note

QC 20170607

Available from: 2017-06-07 Created: 2017-06-07 Last updated: 2017-06-07Bibliographically approved
Fortuna-Zalesna, E., Grzonka, J., Rubel, M., Garcia Carrasco, A., Widdowson, A., Baron-Wiechec, A. & Ciupinski, L. (2017). Studies of dust from JET with the ITER-Like Wall: Composition and internal structure. NUCLEAR MATERIALS AND ENERGY, 12, 582-587
Open this publication in new window or tab >>Studies of dust from JET with the ITER-Like Wall: Composition and internal structure
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2017 (English)In: NUCLEAR MATERIALS AND ENERGY, ISSN 2352-1791, Vol. 12, p. 582-587Article in journal (Refereed) Published
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.

National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-220644 (URN)10.1016/j.nme.2016.11.027 (DOI)000417293300092 ()2-s2.0-85010977239 (Scopus ID)
Note

QC 20171229

Available from: 2017-12-29 Created: 2017-12-29 Last updated: 2018-03-13Bibliographically approved
Garcia Carrasco, A. (2016). Impact of material migration on plasma-facing components in tokamaks. (Doctoral dissertation). Stockholm: KTH Royal Institute of Technology
Open this publication in new window or tab >>Impact of material migration on plasma-facing components in tokamaks
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Plasma-wall interaction plays an essential role in the performance and safety of a fusion reactor. This thesis focuses on the impact of material migration on plasma-facing components. It is based on experiments performed in tokamaks: JET, TEXTOR and ASDEX Upgrade. The objectives of the experiments were to assess fuel and impurity removal under ion cyclotron wall conditioning (ICWC) and plasma impact on diagnostic mirrors.

In wall conditioning studies, tracer techniques based on the injection of rare isotopes (15N, 18O) were used to determine conclusively the impact of the respective gases. For the first time, probe surfaces and wall components exposed to ICWC were examined by surface analysis methods. Discharges in hydrogen were the most efficient to erode carbon co-deposits, resulting in a reduction of the initial deuterium content by a factor of two. It was also found that impurities desorbed under ICWC are partly re-deposited on the wall.

Plasma impact on diagnostic mirrors was determined by surface analysis of test mirrors exposed at JET. Reflectivity of mirrors from the divertor region was severely decreased due to deposits of beryllium, deuterium, carbon and other impurities. This result points out the need to develop mirror maintenance procedures. Neutron damage on mirrors was simulated by ion irradiation in an ion implanter. It was shown that damage levels similar to those expected in the first wall of a fusion reactor do not produce a significant change in reflectivity.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. p. 54
Series
TRITA-EE, ISSN 1653-5146
Keywords
Fusion, material migration, wall conditioning, diagnostic mirrors, plasma-facing materials
National Category
Fusion, Plasma and Space Physics
Research subject
Physics
Identifiers
urn:nbn:se:kth:diva-190903 (URN)978-91-7729-046-9 (ISBN)
Public defence
2016-09-15, Kollegiesalen, Brinellvägen 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20160819

Available from: 2016-08-19 Created: 2016-08-18 Last updated: 2016-08-19Bibliographically approved
Garcia Carrasco, A.Investigation of probe surfaces after ion cyclotron wall conditioning in ASDEX Upgrade.
Open this publication in new window or tab >>Investigation of probe surfaces after ion cyclotron wall conditioning in ASDEX Upgrade
(English)Manuscript (preprint) (Other academic)
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 the 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 on virgin W substrates. 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.

Keywords
ICWC, Erosion-deposition, fuel removal, ion beam analysis, ASDEX Upgrade
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:kth:diva-190898 (URN)
External cooperation:
Note

QC 20160819

Available from: 2016-08-18 Created: 2016-08-18 Last updated: 2016-09-02Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5603-8559

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