|Title||Optimization and characterization of a Pilot-psi cascaded arc with non-LTE numerical simulation of Ar, H-2 gases|
|Publication Type||Journal Article|
|Year of Publication||2009|
|Authors||Z. Ahmad, W.J Goedheer|
|Journal||Plasma Sources Science & Technology|
|Type of Article||Article|
|Keywords||ELECTRON-IMPACT, EXCITATION, H-ATOMS, HYDROGEN ATOM RECOMBINATION, IONIZATION, kinetics, PLASMA, SILICA, SURFACES, THOMSON SCATTERING|
A numerical simulation code, PLASIMO, is used to model non-LTE plasmas in the cascaded arc for hydrogen and argon. The purpose of these simulations is to optimize the cascaded arc plasma source, which is used to produce a high density plasma column in Pilot-psi, a linear device to study plasma surface interaction processes. Results are compared with the experimental findings to validate the model. The effect of a change in the arc channel geometry on the ionization degree is studied. It is found that for the hydrogen arc an increase in length beyond 30mm will not increase the ionization degree, in contrast to widening the arc. With an increase in radius from 2mm to 5mm for a 30mm long arc the degree of ionization of hydrogen increases from 5.4 to 38. For the argon arc an increase both in the length and in the width increases the ionization degree. With an increase in length from 30mm to 40mm for a 2mm wide arc the degree of ionization of argon increases from 14.5 to 17.1, whereas with an increase in radius from 2mm to 5mm for 30mm long arc the same increases from 14.5 to 37.5. To simulate the influence of the wall material, the effect of hydrogen wall association on the degree of ionization and dissociation is studied. Wall association in the nozzle section, where heating is absent, significantly reduces the degree of dissociation, in agreement with the experimental data. In Pilot-psi, the arc is operated in a high magnetic field, so the effect of a magnetic field on the yield of Ar+ and H+ ions leaving the arc is also studied. It is found that with a 3 T magnetic field the Ar+ yield increases from 1.6 x 10(20) to 2.1 x 10(20) (25% increase) while the H+ yield increases from 1.4 x 10(20) to 2.9 x 10(20) (100% increase).
|URL||<Go to ISI>://000262897600030|
|Alternate Title||Plasma Sources Sci. Technol.|
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