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Interaction of relativistic electrons with plasma facing components

Technical Report:

Abstract

Runaway electrons can cause severe damage to plasma facing components of large tokamaks. The designs proposed for the first wall and divertor of the next large fusion experiment, ITER (International Thermonuclear Experimental Reactor), are investigated. Energies of up to 300 MeV per electron and surface energy depositions of 30 MJ/m{sup 2} are assumed. The GEANT code originating from high energy physics was used to model the energy deposition [J/cm{sup 3}] quantitatively as a function of the penetration depth and material. A two dimensional representation of the geometry was chosen. For the third coordinate the assumption of symmetric conditions is very close to reality. The magnetic field was included in the analysis. It causes bending back of reflected charged particles and reduced penetration depth of the electrons due to the gyration of the electrons around the magnetic field lines. The energy deposition in the bulk material for a given surface energy load is roughly independent of the incident angle and energy (above 100 MeV) since the main physical process of the energy loss is the formation of an electromagnetic shower, i.e. rapid dissipation of the initial energy into many electrons, positrons and photons. Typical divertor designs protect the cooling tubes with  More>>
Authors:
Publication Date:
Jul 01, 1992
Product Type:
Technical Report
Report Number:
IPP-1/269
Reference Number:
SCA: 700330; PA: DEN-92:015536; SN: 93000903838
Resource Relation:
Other Information: PBD: Jul 1992
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ITER TOKAMAK; RUNAWAY ELECTRONS; PLASMA; RELATIVISTIC RANGE; 700330; PLASMA KINETICS, TRANSPORT, AND IMPURITIES
OSTI ID:
10104274
Research Organizations:
Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)
Country of Origin:
Germany
Language:
English
Other Identifying Numbers:
Other: ON: DE93742847; TRN: DE9215536
Availability:
OSTI; NTIS (US Sales Only); INIS
Submitting Site:
DEN
Size:
31 p.
Announcement Date:
Jun 30, 2005

Technical Report:

Citation Formats

Bartels, H W. Interaction of relativistic electrons with plasma facing components. Germany: N. p., 1992. Web.
Bartels, H W. Interaction of relativistic electrons with plasma facing components. Germany.
Bartels, H W. 1992. "Interaction of relativistic electrons with plasma facing components." Germany.
@misc{etde_10104274,
title = {Interaction of relativistic electrons with plasma facing components}
author = {Bartels, H W}
abstractNote = {Runaway electrons can cause severe damage to plasma facing components of large tokamaks. The designs proposed for the first wall and divertor of the next large fusion experiment, ITER (International Thermonuclear Experimental Reactor), are investigated. Energies of up to 300 MeV per electron and surface energy depositions of 30 MJ/m{sup 2} are assumed. The GEANT code originating from high energy physics was used to model the energy deposition [J/cm{sup 3}] quantitatively as a function of the penetration depth and material. A two dimensional representation of the geometry was chosen. For the third coordinate the assumption of symmetric conditions is very close to reality. The magnetic field was included in the analysis. It causes bending back of reflected charged particles and reduced penetration depth of the electrons due to the gyration of the electrons around the magnetic field lines. The energy deposition in the bulk material for a given surface energy load is roughly independent of the incident angle and energy (above 100 MeV) since the main physical process of the energy loss is the formation of an electromagnetic shower, i.e. rapid dissipation of the initial energy into many electrons, positrons and photons. Typical divertor designs protect the cooling tubes with a 1 cm thick graphite layer. Melting of such molybdenum (copper) cooling tubes occurs at a heat load of 50 (25) MJ/m{sup 2}. Every additional cm of graphite roughly doubles the runaway protection. Since it is proposed to operate ITER with low cooling water temperatures (T{sub H2O} < 150deg C), water pressurization due to runaway electron impact is not a serious problem if the cooling pipes do not melt. If the first material facing the plasma is metallic, melting must be expected for heat loads of around 20 MJ/m{sup 2}. (orig.).}
place = {Germany}
year = {1992}
month = {Jul}
}