Speaker
Dr
Emmanuel Joffrin
(CEA Cadarache)
Description
Generation of run-aways electron (RE) beams is one of the major risks for the successful exploitation of ITER. In the past 15 years JET has been exploring the physics of run-away creation and the dynamics of the beam with different wall materials, namely carbon and Berylium/Tungsten mix (ITER-like wall). Recently, it has been observed experimentally that a full-blown run-away beam cannot be mitigated in JET using disruption mitigation valves (DMV) in contrast to smaller devices (DIII-D or ASDEX Upgrade). The working hypothesis to explain this observation is that the run-away beam is screened by the high density cold plasma background surrounding the beam. These observations have prompted the launch of an international project (ITER Organisation, the US Department of Energy and EURATOM) for the installation of a shattered pellet injector (SPI) on the JET device with the purpose to demonstrate that it has the necessary capability for reliable and robust mitigation of the effects of disruptions and vertical displacement events (VDEs) while preventing runaway formation. The main focus in the next JET 2018 experimental campaigns is to assess the efficacy of SPI on runaway avoidance and runaway energy dissipation which are the presently foreseen two lines of defence in ITER.
This presentation will review the key results achieved by run-away experiments in JET, provide a summarized description of the future shattered pellet injector and also the key objectives of the run-away experiments in 2018.
Primary author
Dr
Emmanuel Joffrin
(CEA Cadarache)
Co-authors
Dr
Cedric Reux
(CEA)
Larry Baylor
(ORNL)
Dr
Larry Baylor
(ORNL)
Michael Lehnen
(ITER Organization)
Dr
Michael Lehnen
(ITER Organisation)
