Runaway electrons dynamics and confinement in Tore-Supra
Ohmic discharges in TORE-SUPRA are sufficiently long (approx. 6s) for runaway electrons ( R.E.) to reach a steady energy state. Their energy limit is determined by the balance between parallel electric field acceleration (20 MeV/V.s in TORE-SUPRA) and radiation losses due to the curvature of the trajectories. When R.E. energy is supposed to be only parallel, this provides an estimate of the order of 70 MeV (a value usually called the "synchrotron limit") reached in less than 2 seconds. Experimental observations on TORE-SUPRA of photoneutron emission together with residual induced radioactivity in the first wall components tend to prove that the actual value is much lower than 70 MeV (i.e. 15-35 MeV). Earlier observations in ORMAK, PLT and TFR already showed R.E. energy as slightly less than expected from standard loop voltage acceleration calculations. Explanations given for this lack of energy as skin-effect lowering the electric field during the ramp-up phase or balance between continuous creation and losses seem not to hold on TORE-SUPRA. Therefore another mechanism must be considered to explain the R.E. energy limitation.
Bibliographic Reference: Paper presented: 16th European Conference on Controlled Fusion and Plasma Physics, Venezia (IT), March 13-17, 1989
Availability: Available from (1) as Paper EN 34466 ORA
Record Number: 198910801 / Last updated on: 1994-12-01
Original language: en
Available languages: en