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Preliminary calculations of expected signal levels of a thin Faraday foil lost alpha particle diagnostic for International Thermonuclear Experimental Reactor

Journal Article · · Review of Scientific Instruments
DOI:https://doi.org/10.1063/1.1785279· OSTI ID:20636686
; ;  [1]
  1. Department of Physics, Colorado School of Mines, Golden, Colorado (United States)
Thin Faraday collectors are being considered as a diagnostic of lost alpha particles on International Thermonuclear Experimental Reactor (ITER). In an effort to evaluate the viability of this diagnostic, we are undertaking a series of calculations of the signal levels (A/cm{sup 2}) for such devices. Preliminary results assuming a model high yield ITER plasma have been obtained for locations near the outer wall assuming a toroidally symmetric vacuum vessel. We find signal levels to be a strong function of foil location and orientation. Specifically the signal level will be optimized at a vertical location 0.5 m above the machine midplane and with the normal to the foil directed in the lower, radially outward, toroidally counterclockwise octant. A foil thus oriented at a radial distance of 15 cm from the vessel wall at a height of 0.583 m above the machine midplane will have an efficiency of 3.5x10{sup -8}/cm{sup 2} for alpha particles which undergo classic loss during the first ten revolutions around the torus during this model plasma. For the assumed D-T fusion power of this model plasma of 410 MW, this calculated efficiency will correspond to a measured current in the Faraday foil of 1.7 {mu}A/cm{sup 2}. Future, more realistic calculations must incorporate the effects of an asymmetrical vessel and of toroidal field ripple.
OSTI ID:
20636686
Journal Information:
Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 10 Vol. 75; ISSN 0034-6748; ISSN RSINAK
Country of Publication:
United States
Language:
English