Abstract
The presented data refer to the Shattered Pellet Injector (SPI) experiments carried out at JET in 2019-2020. This paper is a full journal version of the data originally presented as posters at TMPDM_2020 and EPS_2021. This paper presents various aspects of the interaction of pellets with plasma and associated disruptions. The experiment was performed with I p = (1.1-3.1) MA plasmas and mainly with Ne + D2 pellet composition, but also with Ar pellets. The Current Quench (CQ) time, τ 80−20, is the key characteristic of mitigation effectiveness. A pellet with a high content of Ne or Ar can reduce the CQ duration below the upper required JET threshold. Plasmas with high (thermal + internal poloidal magnetic) pre-disruptive plasma energy require a high content of Ne pellets to obtain a short CQ duration. Pellets with a small amount of Ne (and accordingly large amount of D), instead of causing a mitigated CQ, create the conditions for a ‘cold’ Vertical Displacement Events (VDE). The SPI was applied to plasma with different status: mainly to normal (‘healthy’) plasma, i.e. not prone to disruption, post-disruptive and VDE plasma. This study shows that SPI effectiveness in terms of CQ duration and, accordingly, EM loads does not depend on the state of the plasma, whether it is ‘healthy’ or post-disruptive plasma. SPI has been shown to reduce the axisymmetric vertical vessel reaction forces by about (30-40) % compared to unmitigated disruptions. On JET, the VDE, whether ‘hot’ or ‘cold’, always creates the conditions for a toroidal asymmetry in the plasma, so the VDE on the JET is referred to as Asymmetric VDE (AVDE). The interrupting of VDE and prevention of AVDE with SPI has been demonstrated. Thus, the effectiveness of disruption mitigation using SPI has been confirmed.
| Original language | English |
|---|---|
| Article number | 075615 |
| Journal | Physica Scripta |
| Volume | 99 |
| Issue number | 7 |
| DOIs | |
| State | Published - Jul 1 2024 |
Funding
This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No 101052200 - EUROfusion) and from the EPSRC [grant number EP/W006839/1]. To obtain further information on the data and models underlying this paper please contact [email protected]. Views and opinions expressed are however those of the authors only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them. The JET SPI experiments have been carried out as collaboration between EUROfusion and the ITER Organization. The JET SPI has received funding through the ITER project. The views and opinions expressed herein do not necessarily reflect those of the ITER Organization. The work was also supported in part by the U.S. Department of Energy under Contracts No. DE-AC05-00OR22725, grant DE-SC0023274 and by the US Department of Energy, Office of Science, Office of Fusion Energy Sciences under Award No. DE-FG02-06ER54852 . The authors would like to acknowledge G Szepesi, V Drozdov and P Abreu for support in providing and interpreting EFIT data, YuF Baranov for help in assessing ECE, L N Khimchenko and R Henriques for help in interpreting the radiation data. The authors would like to acknowledge O Sauter, A Javier, R Khayrutdinov and E Nardon for fruitful discussions on the impact of SPI on VDE. This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No 101052200 - EUROfusion) and from the EPSRC [grant number EP/W006839/1]. To obtain further information on the data and models underlying this paper please contact [email protected]. Views and opinions expressed are however those of the authors only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them. The JET SPI experiments have been carried out as collaboration between EUROfusion and the ITER Organization. The JET SPI has received funding through the ITER project. The views and opinions expressed herein do not necessarily reflect those of the ITER Organization. The work was also supported in part by the U.S. Department of Energy under Contracts No. DE-AC05-00OR22725, grant DE-SC0023274 and by the US Department of Energy, Office of Science, Office of Fusion Energy Sciences under Award No. DE-FG02\u201306ER54852 . The authors would like to acknowledge G Szepesi, V Drozdov and P Abreu for support in providing and interpreting EFIT data, YuF Baranov for help in assessing ECE, L N Khimchenko and R Henriques for help in interpreting the radiation data. The authors would like to acknowledge O Sauter, A Javier, R Khayrutdinov and E Nardon for fruitful discussions on the impact of SPI on VDE.
Keywords
- VDE
- disruption
- shattered pellet
- tokamak