Progress in the Understanding of Gridded Inertial Electrostatic Confinement Devices at the University of Wisconsin

Kulcinski, G.L.; Santarius, J. F.; Emmert, G.A.; Bonomo, Richard; Becerra, Gabriel; Fancher, Aaron; Garrison, Lauren M.; Hall, K. B.; Jasica, Matthew J.; McEvoy, A. M.; Navarro, Marcos; Michalak, M. K.; Schuff, C. M.

doi:10.13182/fst14-934

Cited by 2 publications

(1 citation statement)

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“…Glow discharges in which ions and neutrals are significantly energetic are relatively uncommon, and have mostly been studied in IEC for non-power fusion applications. Early IEC work was conducted at lower pressures [3][4][5][6], but since a simple discharge source was developed at the University of Illinois in the 1990s [7][8][9][10][11] research has been directed towards better understanding and improving the efficiency of benchtop fusion devices [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31], since near-term applications increase with performance. These generally use a spherical or cylindrical hollow wire-grid cathode, operated either as self-sustained 'transparent cathode' discharge (TCD) or with an ionisation source.…”

Section: Introductionmentioning

confidence: 99%

Optical emission from a ‘beam mode’ transparent cathode glow discharge

Hardiment

Bowden

2021

Plasma Sources Sci. Technol.

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We investigate optical emission from a low-pressure ‘beam mode’ inertial electrostatic confinement glow discharge, created using cylindrical grid electrodes, having cathode inside a grounded, concentric anode. Spectral line distributions were measured in helium from this and a hollow cathode mode, with four lines emitted from singlet and triplet states with n = 3 and L = P and D compared against simple models for impact excitation by electrons and by ions and neutrals, suggesting much beam mode emission is caused by fast neutrals, and a significant component also caused by electrons. Beam mode emission occurs in a pattern of radial lines, that pass through aligned electrode apertures and extend across the chamber. Shadows cast by the electrode wires indicate electrically-neutral, beam-like sources of excitation, that cross the electrode assembly from bright radial lines in the opposing inter-electrode space, and calculated potential distributions show lensing surfaces around the anode grid apertures, focussing for inward-drifting ions. These indicate the emission pattern is caused by radially-convergent ion beams, and co-linear beams of fast neutrals produced in these. Emission was also observed with various alterations made to the electrode arrangement: with the anode removed, no beams were observed; with the cathode apertures rotated out of phase with those of the anode, bright radial beams between the electrodes followed the distribution of anode apertures; similar beams appeared with the grid cathode replaced by a solid version. In these experiments, progressive obstruction of pathways through the cathode caused increasing reduction in the beam pattern of emission beyond the anode radius, and in discharge perveance at similar pressure and voltage. Beam-like emission was also observed for a parallel-planar configuration, in which a cathode grid was held between two identical anode grids. The beam mode is shown to be a convergent, anode-focussed ion beam discharge, distinct to the star mode described elsewhere.

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