Burn-up of fusion-produced tritons and³He ions in PLT and PDX

Abstract

He ion 'burn-up' was measured on the PLT and PDX tokamaks by detection of the 14 MeV neutron and 15 MeV proton emission. In discharges with B,j>> 2 T, the measured ^e and triton burn-up is consistent (within a factor of three) with predictions based on classical theories of ion confinement and slowing down. In discharges with weaker toroidal fields but constant plasma current, the burn-up of both ions fell by more than a factor of ten so that the observed burn-up was significantly less than expected classically.

The weak effect of static, externally imposed, helical fields on fusion product confinement in the DIII-D tokamak

“…Three separate calculations are employed. The simplest, the steady state MIS code [26], ignores spatial and velocity space diffusion;…”

Comparison of experimental and theoretical fast ion slowing-down times in DIII-D

“…Unfortunately, the diverted plasma flows may intersect such necessary obstructions as diagnostics and antennas before reaching an area where it is feasible to collect the diverted plasma, which results in enhanced impurity generation close to the central plasma. This can present a significant problem in stellarators where a naturally occurring divertor structure often distributes particle fluxes over a large portion of the device [5]. The work reported here shows that in a stellarator geometry the addition of a small vertical magnetic field can dramatically alter the locations of plasma flow out of the coil volume.…”

Confinement of Fusion Reaction Products during the Fishbone Instability

“…7 '" The absolute calibration was confirmed by puffing 3 He gas and taking the 3 IIc density to be | of the resulting rise in electron density. 7 The absolute accuracy of the measurement of the emission is about a factor of two. The relative accuracy is determined primarily by counting statistics Most fusion-produced 3 He ions are born near the hot center of the plasma.…”

“…u -D + neutral beam injection that suggest that non-resonant 0.8 MeV 3 He ions experience severe losses during fishbone activity. 7 The absolute magnitude of the 15 MeV proton emis sion was detected with 10 ms time response using a horizontally inserted surface barrier detector. 7 '" The absolute calibration was confirmed by puffing 3 He gas and taking the 3 IIc density to be | of the resulting rise in electron density.…”

“…7 The absolute magnitude of the 15 MeV proton emis sion was detected with 10 ms time response using a horizontally inserted surface barrier detector. 7 '" The absolute calibration was confirmed by puffing 3 He gas and taking the 3 IIc density to be | of the resulting rise in electron density. 7 The absolute accuracy of the measurement of the emission is about a factor of two.…”