Pneumatic hydrogen pellet injection system for the ISX tokamak

Milora, S.L.; Foster, C.A.

doi:10.1063/1.1135856

“…Design details and operation of the pellet injector are described elsewhere [11]. Pellet mass is monitored periodically during an experimental run by trapping pellets in a known volume and measuring the resultant pressure rise.…”

Section: Experimental Arrangementmentioning

confidence: 99%

Multiple Eigenvalues of the Laplace Operator

1988

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Initial hydrogen pellet injection experiments have been performed in plasmas characterized by a low particle re-cycle fraction resulting from the action of a poloidal magnetic divertor. As in past experiments, the interaction of the fuel with the plasma is observed to be adiabatic. Moreover, the pellet mass is accounted for in the core plasma density increase, indicating only a small loss of fuel while the pellet transits the divertor scrape-off plasma. The effect of edge re-cycling on the density was studied by comparing divertor (low-re-cycle) and limiter (high-re-cycle) plasmas; the distinction between the two cases is clearest in the edge plasma region where the density decay rates differ most. Particle transport subsequent to pellet injection is less ambiguous for divertor cases, and, by comparing the density profile relaxation and the electron temperature recovery with an empirical transport model that closely approximates the pre-injection plasma conditions, it is concluded that the plasma confinement properties do not deteriorate as a result of pellet injection. The principal difference between central and edge fuelling is demonstrated by a peaking of the density profile and an extended decay time for the density perturbation.

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“…The injector is a gas-driven device capable of injecting a single solid hydrogen pellet of nominal 1 mm diameter at speeds in the 600-to-1000 nvs" 1 range. Design details and operation of the pellet injector are described elsewhere [11]. Pellet mass is monitored periodically during an experimental run by trapping pellets in a known volume and measuring the resultant pressure rise.…”

Section: Experimental Arrangementmentioning

confidence: 99%

Pellet injection into PDX diverted plasmas

Milora

¹

,

Schmidt²,

Houlberg

³

et al. 1982

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Initial hydrogen pellet injection experiments have been performed in plasmas characterized by a low particle re-cycle fraction resulting from the action of a poloidal magnetic divertor. As in past experiments, the interaction of the fuel with the plasma is observed to be adiabatic. Moreover, the pellet mass is accounted for in the core plasma density increase, indicating only a small loss of fuel while the pellet transits the divertor scrape-off plasma. The effect of edge re-cycling on the density was studied by comparing divertor (low-re-cycle) and limiter (high-re-cycle) plasmas; the distinction between the two cases is clearest in the edge plasma region where the density decay rates differ most. Particle transport subsequent to pellet injection is less ambiguous for divertor cases, and, by comparing the density profile relaxation and the electron temperature recovery with an empirical transport model that closely approximates the pre-injection plasma conditions, it is concluded that the plasma confinement properties do not deteriorate as a result of pellet injection. The principal difference between central and edge fuelling is demonstrated by a peaking of the density profile and an extended decay time for the density perturbation.

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“…Existing pellet injector designs were reviewed and evaluated for their applicability to the TPOP experiment. In an early injector developed by Milora and co-workers, [12][13][14][15] pellets were formed at a fill station by direct condensation of hydrogen from the gas phase and then transported to the gun barrel in a disk-shaped carrier, which sheared off any excess solid when it was rotated from the fill station to the firing position. Lafferanderie and co-workers 16 later used an approach that they termed in situ condensation, in which a 6-mm-OD pellet was frozen in a 6-mm-long cooled section at the breech end of a barrel in a position ready for firing.…”

Section: Figuresmentioning

confidence: 99%