Magnetic field threshold for runaway generation in tokamak disruptions
Journal article, 2009

Experimental observations show that there is a magnetic field threshold for runaway electron generation in tokamak disruptions. In this work, two possible reasons for this threshold are studied. The first possible explanation for these observations is that the runaway beam excites whistler waves that scatter the electrons in velocity space prevents the beam from growing. The growth rates of the most unstable whistler waves are inversely proportional to the magnetic field strength. Taking into account the collisional and convective damping of the waves it is possible to derive a magnetic field threshold below which no runaways are expected. The second possible explanation is the magnetic field dependence of the criterion for substantial runaway production obtained by calculating how many runaway electrons can be produced before the induced toroidal electric field diffuses out of the plasma. It is shown, that even in rapidly cooling plasmas, where hot-tail generation is expected to give rise to substantial runaway population, the whistler waves can stop the runaway formation below a certain magnetic field unless the postdisruption temperature is very low.

Author

Tünde Fülöp

Chalmers, Applied Physics, Nuclear Engineering

Håkan Smith

The University of Warwick

Gergö Pokol

Budapest University of Technology and Economics

Physics of Plasmas

1070-664X (ISSN) 1089-7674 (eISSN)

Vol. 16 2 022502- 022502

Driving Forces

Sustainable development

Areas of Advance

Energy

Roots

Basic sciences

Subject Categories

Fusion, Plasma and Space Physics

DOI

10.1063/1.3072980

More information

Latest update

3/19/2018