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chemical physics of discharges - Argonne National Laboratory

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'<br />

112<br />

axial diffusion through the discharge one, axial diffusion through the reactor<br />

zone, production, recombination on the end plate, recombination in the discharge<br />

zone, and recombination in the reactor zone. Thus, the interaction between the<br />

rate <strong>of</strong> production and the other rate processes can be conveniently characterized<br />

by seven dimensionless groups: 11<br />

-<br />

U2<br />

=<br />

RI n<br />

2-<br />

RIL -<br />

rate <strong>of</strong> atom production in the discharge zone = 'e2<br />

rate <strong>of</strong> radial diffusion to the wall D12<br />

rate <strong>of</strong> atom production in the discharge zone<br />

p M<br />

or &R<br />

rate <strong>of</strong> atom recombination within the discharge zone k: YVl<br />

rate <strong>of</strong> atom production in the discharge zone<br />

P !Go,%&!<br />

rate <strong>of</strong> atom recombination within the reactor zone kl yV1<br />

rate <strong>of</strong> atom production in the discharge zone - W R<br />

rate <strong>of</strong> atom recombination on the end plate - Y'F1<br />

rate <strong>of</strong> atom production in the discharge zone E k&<br />

rate <strong>of</strong> axial convection VZ<br />

rate <strong>of</strong> atom production in the discharge zone -kdRM<br />

rate <strong>of</strong> axial diffusion through the discharge zone D12<br />

rate <strong>of</strong> atom production .in the discharge zone *L I<br />

rate <strong>of</strong> axial diffusion through the reactor zone. D12<br />

These dimensionless groups can be further condensed to,yield just two<br />

groups relating the overall rates <strong>of</strong> atom production, transport, and loss:<br />

= rate <strong>of</strong> atom production = U'<br />

loss rate <strong>of</strong> atom loss 115' + 116Iz + l/p<br />

-<br />

( 124 I<br />

@loss - rate <strong>of</strong> atom loss - l/k' + 1/612 + 1/u2 r<br />

-<br />

Otransport<br />

- R/L + RIM + $ + 1<br />

In a steady-state experiment, there must be a competition between two<br />

rate processes -- a source and a sink. If the source and sink are spatially<br />

separated, then a transport process may further complicate the results. In<br />

the present case, the rate <strong>of</strong> atom production can be measured only if<br />

rod<br />

1, for if the source is much greater than the sink, no concentration<br />

@loss<br />

gradient can exist.<br />

2. Significance <strong>of</strong> k&<br />

For purposes <strong>of</strong> discussion, assume that the rate parameter Id represents<br />

the rate <strong>of</strong> production <strong>of</strong> atomic hydrogen(c;) via the following ion-electron<br />

recombination reaction,<br />

H$ + e' A H + H<br />

(125)<br />

!<br />

f

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