The effect of vertical displacements on the runaway electron avalanche in ITER mitigated disruptions
In order to prepare the operation of ITER, it is important to estimate the amplitude of the runaway electron (RE) current that could appear following disruptions at large plasma currents. Theoretically, the avalanche gain of RE population on a toroidal flux surface (TFS) is an exponential function o...
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IOP Publishing
2024-01-01
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| Series: | Nuclear Fusion |
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| Online Access: | https://doi.org/10.1088/1741-4326/ad8d66 |
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| author | C. Wang E. Nardon F.J. Artola V. Bandaru M. Hoelzl the JOREK team |
| author_facet | C. Wang E. Nardon F.J. Artola V. Bandaru M. Hoelzl the JOREK team |
| author_sort | C. Wang |
| collection | DOAJ |
| description | In order to prepare the operation of ITER, it is important to estimate the amplitude of the runaway electron (RE) current that could appear following disruptions at large plasma currents. Theoretically, the avalanche gain of RE population on a toroidal flux surface (TFS) is an exponential function of the change in the poloidal magnetic flux Δ ψ on that TFS. However, once a TFS is open, REs on it escape rapidly and can no longer proliferate. It is expected that the vertical motion of the plasma during a disruption could lead to the opening of TFSs as the plasma cross-section is pushed into the wall. The influence of this vertical motion on the RE avalanche gain was rarely considered in previous studies. This study investigates the RE generation in ITER major disruptions and hot vertical displacement events mitigated by the injection of neon and hydrogen, using an axisymmetric 2D model on the JOREK code. Compared to those with a stationary plasma, our simulations show a smaller Δ ψ on a given TFS by the time it becomes open as a result of the vertical motion. The maximum potential avalanche gain is thus reduced from $10^{16}-10^{20}$ without considering the vertical motion to $10^{9}-10^{12}$ , depending on the plasma dynamics during the disruption. In addition, the RE current produced by a typical nuclear seed (∼ 10 mA) at ITER is investigated. |
| format | Article |
| id | doaj-art-6a46b1915ecb4f48a9022af9da64692d |
| institution | Kabale University |
| issn | 0029-5515 |
| language | English |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
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| series | Nuclear Fusion |
| spelling | doaj-art-6a46b1915ecb4f48a9022af9da64692d2024-11-15T10:44:39ZengIOP PublishingNuclear Fusion0029-55152024-01-0165101601210.1088/1741-4326/ad8d66The effect of vertical displacements on the runaway electron avalanche in ITER mitigated disruptionsC. Wang0https://orcid.org/0009-0009-7621-6581E. Nardon1https://orcid.org/0000-0003-0427-2292F.J. Artola2V. Bandaru3M. Hoelzl4https://orcid.org/0000-0001-7921-9176the JOREK teamIRFM , CEA Cadarache, 13108 Saint-Paul-lez-Durance, France; École Polytechnique Fédérale de Lausanne (EPFL) , Swiss Plasma Center (SPC), CH-1015 Lausanne, SwitzerlandIRFM , CEA Cadarache, 13108 Saint-Paul-lez-Durance, FranceITER Organization , Route de Vinon-sur-Verdon, 13115 Saint-Paul-lez-Durance, FranceIndian Institute of Technology Guwahati , Guwahati, Assam 781039, IndiaMax Planck Institute for Plasma Physics , Boltzmannstr. 2, 85748 Garching b. M., GermanyIn order to prepare the operation of ITER, it is important to estimate the amplitude of the runaway electron (RE) current that could appear following disruptions at large plasma currents. Theoretically, the avalanche gain of RE population on a toroidal flux surface (TFS) is an exponential function of the change in the poloidal magnetic flux Δ ψ on that TFS. However, once a TFS is open, REs on it escape rapidly and can no longer proliferate. It is expected that the vertical motion of the plasma during a disruption could lead to the opening of TFSs as the plasma cross-section is pushed into the wall. The influence of this vertical motion on the RE avalanche gain was rarely considered in previous studies. This study investigates the RE generation in ITER major disruptions and hot vertical displacement events mitigated by the injection of neon and hydrogen, using an axisymmetric 2D model on the JOREK code. Compared to those with a stationary plasma, our simulations show a smaller Δ ψ on a given TFS by the time it becomes open as a result of the vertical motion. The maximum potential avalanche gain is thus reduced from $10^{16}-10^{20}$ without considering the vertical motion to $10^{9}-10^{12}$ , depending on the plasma dynamics during the disruption. In addition, the RE current produced by a typical nuclear seed (∼ 10 mA) at ITER is investigated.https://doi.org/10.1088/1741-4326/ad8d66runaway electronsdisruptionsMHDITERJOREKVDE |
| spellingShingle | C. Wang E. Nardon F.J. Artola V. Bandaru M. Hoelzl the JOREK team The effect of vertical displacements on the runaway electron avalanche in ITER mitigated disruptions Nuclear Fusion runaway electrons disruptions MHD ITER JOREK VDE |
| title | The effect of vertical displacements on the runaway electron avalanche in ITER mitigated disruptions |
| title_full | The effect of vertical displacements on the runaway electron avalanche in ITER mitigated disruptions |
| title_fullStr | The effect of vertical displacements on the runaway electron avalanche in ITER mitigated disruptions |
| title_full_unstemmed | The effect of vertical displacements on the runaway electron avalanche in ITER mitigated disruptions |
| title_short | The effect of vertical displacements on the runaway electron avalanche in ITER mitigated disruptions |
| title_sort | effect of vertical displacements on the runaway electron avalanche in iter mitigated disruptions |
| topic | runaway electrons disruptions MHD ITER JOREK VDE |
| url | https://doi.org/10.1088/1741-4326/ad8d66 |
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