Disruption

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A disruption is a violent event that terminates a magnetically confined plasma, usually the consequence of a rapidly growing instability, often of the MHD type. [1] In a disruption, the temperature drops drastically and heat and particles are released from confinement on a short timescale and dumped on the vessel wall, causing damage in proportion to the stored energy. The loss of confinement is associated with the production of runaway electrons, which may also produce damage. [2]

The magnetic effects of a disruption (associated with the sudden loss of the net plasma current) generate large magnetic forces on the metallic structures surrounding the plasma (the vessel, the coils, and the supporting structure), also known as Vertical Displacement Events, which may induce mechanical damage.

Influence of the magnetic configuration

Due to the fact that in stellarators, confinement does not depend on the plasma current, disruptions are less severe or inexistent in such machines, which is a significant advantage for the design of a future stellarator reactor. [3]

Avoidance and mitigation

Disruption avoidance or mitigation is an important topic for ITER. [4]

Disposing of a good capacity for predicting disruptions is essential when implementing mitigation measures. [5] [6] [7]

References

  1. P.C. de Vries et al, Survey of disruption causes at JET, Nucl. Fusion 51 (2011) 053018
  2. A. Cardella et al, Effects of plasma disruption events on ITER first wall materials, Journal of Nuclear Materials 283-287, Part 2 (2000) 1105-1110
  3. G.H. Neilson et al, Physics issues in the design of high-beta, low-aspect-ratio stellarator experiments, Phys. Plasmas 7 (2000) 1911
  4. ITER Physics Expert Group on Disruptions, Plasma Control, and MHD, ITER Physics Basis Chapter 3: MHD stability, operational limits and disruptions, Nucl. Fusion 39 (1999) 2251-2389
  5. G. A. Rattá, J. Vega, A. Murari, M. Johnson, and JET-EFDA Contributors, Feature extraction for improved disruption prediction analysis at JET,Rev. Sci. Instrum. 79 (2008) 10F328
  6. G.A. Rattá, J. Vega, A. Murari, G. Vagliasindi, M.F. Johnson, P.C. de Vries and JET EFDA Contributors, An advanced disruption predictor for JET tested in a simulated real-time environment, Nucl. Fusion 50 (2010) 025005
  7. G.A. Rattá, J. Vega, A. Murari, JET-EFDA Contributors, Improved feature selection based on genetic algorithms for real time disruption prediction on JET Fusion Engineering and Design 87 (2012) 1670–1678