Response of an ion–ion plasma to dc biased electrodes

Abstract

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Negative ion extraction from hydrogen plasma bulk

“…7 The negative ion to electron density ratio (electronegativity a n À =n e ) is one of the most important parameter characterizing electronegative plasmas. [8][9][10][11][12][13][14][15][16][17][18][19][20][21] It was recently shown 21 that unmagnetized electronegative plasmas could be classified in four regimes according to a. In the lowest regime a < ffiffiffiffiffiffiffiffiffiffiffiffiffi 1=8pl p (l ¼ m e /M is the electron to ion mass ratio), the bulk plasma potential is the most positive in the system and negative ions are confined within the plasma bulk by classical positive sheaths.…”

Extraction and acceleration of ions from an ion-ion plasma - application to space propulsion

“…When the electronegativity becomes high and plasma tends towards ionion plasma, the IV-characteristic becomes symmetrical [4,6].…”

“…The analyzer has four plane grids and a collection plate and is 1 mm long [6]. The entrance grid G, facing the plasma, is fixed on a grounded 50 mm-diameter diaphragm with an aperture 3 mm in diameter to reduce the open area seen by the plasma (to sample the plasma).…”

“…We recently investigated in a time-averaged mode the influence of DC biased electrodes on the ion-ion plasma potential and the possibility to accelerate positive ions from the ion-ion region in order to create beams with controllable energy/velocity in the first PEGASES prototype [6].…”

Electron energy distribution function and plasma parameters across magnetic filters

“…[2][3][4][5] This technique of electron cooling has been used in negative ion sources for plasma fusion, 6 in the formation of ion-ion plasmas for deep trench etching 7,8 and in space propulsion thrusters. 9,10 Although magnetic filters were extensively used, most of the experiments where electron temperature was measured were performed at a mixed condition where filtering mechanism was coupled with the plasma expansion (both phenomena resulting in electron cooling). 11,12 The measurements, using Langmuir probes and gridded analysers, suffered from many limitations of the probe diagnostics associated with magnetic field, rf plasma potential, and incorrect use of the probe diagnostics that resulted in inconsistent and mutually contradictive data.…”