Energy deposition and radial decay of runaway electrons in a disruption at TEXTOR

摘要

A heat load experiment was carried out with a new kind of probe for the detection of the damage caused by runaway electrons. The probe was inserted into the plasma edge of the tokamak TEXTOR during an induced disruption. The damages, caused by the disruption generated runaway electrons in the probe material, are evaluated by metallographical and thermogravimetrical methods. In comparison with 3D Geant4 code based Monte Carlo simulations of the runaways information about the energy spectrum and the radial decay of the runaway beam behind a limiter are deduced. The results are in good agreement with an exponential energy spectrum (e-folding energy 3-9 MeV) and corresponding exponential or linear radial decay. Reasonable parameter ranges for the distributions are given. Additional simulations show that the measurement gives the strongest results for the spectral part of the runaways with energies between 8 and 16 MeV.