Jul 2 – 6, 2018
Žofín Palace
Europe/Prague timezone

P1.1042 A simplified approach to the physics of runaway electron beam dissipation in tokamak disruptions

Jul 2, 2018, 2:00 PM
2h
Mánes

Mánes

Masarykovo nábřeží 1, 110 00 Praha 1

Speaker

Jose Ramon Martin-Solis

Description

See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.1042.pdf A SIMPLIFIED APPROACH TO THE PHYSICS OF RUNAWAY ELECTRON BEAM DISSIPATION IN TOKAMAK DISRUPTIONS∗ J. R. Martin-Solis 1 , E.M. Hollmann 2 , M. Lehnen 3 and A. Loarte 3 1 Universidad Carlos III de Madrid, Avda.Universidad 30, Leganes, 28911-Madrid, Spain. 2 University of California-San Diego, La Jolla, California 92093-0417, USA. 3 ITER Organization, Route Vinon sur Verdon, CS90046 13067 St. Paul-lez-Durance, France. ABSTRACT The injection of large amounts of high-Z impurities by Massive Gas Injection (MGI) or Shattered Pellet Injection (SPI) constitutes the most promising candidate for the mitigation of runaway electrons during disruptions in large devices like ITER [1,2]. In this paper, the dissipation and decay of the runaway current by injection of high-Z impurities during tokamak disruptions is analyzed using a simplified approach, based on the kinetic treatment of Ref. [3], which includes the effect of the collisions with the plasma particles and the impurity ions, the synchrotron radiation losses associated with the pitch angle scattering of the runaway electrons when colliding with the impurity atoms as well as the bremsstrahlung radiation. The model allows to get simple estimates of the runaway current duration, the runaway distribution function and energy during the dissipation phase. A comparison of the effects associated with the different runaway loss mechanisms (collisions, synchrotron and bremsstrahlung radiation losses) will be presented . Extrapolations to ITER indicate that injection of a few kPa · m3 of Ar could be a promising scenario for runaway electron dissipation during disruptions if the impurities can be efficiently delivered into the plasma. Effects associated with the runaway scraping-off due to the VDE of the runaway beam during the decay of the current will be also considered. [1] E.M. Hollmann et al., Phys.Plasmas 22, 021802 (2015). [2] M. Lehnen et al., J. Nucl. Mater. 3948, 463 (2015). [3] P. Aleynikov and B.N. Breizman, Phys.Rev.Lett. 114, 155001 (2015). ∗ This work was carried out with financial support from Dirección General de Investigación, Cientı́fica y Técnica, Project No. ENE2015-66444-R (MINECO/FEDER, UE). ITER is the Nuclear Facility INB no. 174. This paper explores physics processes during the plasma operation of the tokamak when disruptions take place; nevertheless the nuclear operator is not constrained by the results of this paper. The views and opinions expressed herein do not necessarily reflect those of the ITER Organization.

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