Performance and analysis of an electron cyclotron resonance plasma cathode

Abstract

A scalable electron cyclotron resonance ͑ECR͒ plasma source was investigated for plasma cathode applications. The rectangular source utilized permanent magnets to establish the ECR condition. The microwave applicator region was windowless, making the source applicable to sputtering environment applications. The source was characterized using primarily two diagnostics: ͑1͒ a near-field and far-field Langmuir probe and ͑2͒ a downstream electron extraction electrode. Source operation and plasma properties were characterized at low pressures ranging from 0.2 to 5 mTorr and power levels up to 250 W. Evidence of grad-B drift in the plane of the source was observed. Extracted currents agreed well with predictions.

Study of electron-extraction characteristics of an inductively coupled radio-frequency plasma neutralizer

“…The current-voltage characteristics of the RPN with various orifices are presented in the figure 4. The hysteresis of orifice #1 is similar to that obtained by previous research on RF cathodes [9][10][11] or anode spots [14][15][16]19]. Baalrud et al [15] have explained the hysteresis behavior of an anode spot, suggesting that such spots will form when there are equal densities of ions and electrons in a Debye cube near the orifice.…”

“…A double-sheath structure should be formed between the anode spot and the main plasma, making the potential distribution similar to that shown in figure 1. Meanwhile, the probe potential before the anode-spot formation is a negative value of about −0.2 V, becoming positive afterward as the V Bias increases to a critical value about 40 V. In this case, the anode spot looks like a spherical fireball also observed by other researchers [9][10][11]. The surface area of the spherical fireball is much larger than the aperture area, meaning the electron current becomes more than ten times its original value.…”

“…To overcome these application constraints, insert-free plasma cathodes have been introduced in recent years, such as capacitively [3] and inductively [1,2,[4][5][6][7][8][9][10] coupled RF plasma cathodes (CCPCs and ICPCs, respectively), electron-cyclotronresonance cathodes (ECRCs) [11,12], and helicon cathodes [13,14]. The efficiency of an ICPC is better than that of a CCPC or an ECRC under low source power and low volume-flow rate, and the helicon cathode needs a strong magnetic field and high-RF power.…”

Study of the Discharge Chamber Magnetic Field Configuration Effects on the Electron Cyclotron Resonance (ECR) Microwave Ion Thruster

“…Another ECR plasma cathode that was used as a neutralizer was demonstrated in. 2 This cathode which was studied at the University of Michigan in Ann Arbor, was investigated in terms of discharge and electron extraction properties. The maximum electron current can be extracted was on the order of 0.6 A, for an argon gas flow rate of 5.6 sccm, with a discharge voltage difference of 40 V and 200 W of microwave power.…”

Characterization of a Waveguide ECR Plasma Source

“…Another set of approaches used permanent magnets to set up electron cyclotron resonance (ECR) heating zones, and used microwaves to heat the plasma discharge within these zones. In this vein, sources have been developed that utilize a coax-fed antenna 9 or a magnetic grill assembly 10 to create an ECR discharge. Also, a wire antenna has been used to generate an "off-resonance" discharge, in which the applied magnetic field is slightly stronger than that required for ECR breakdown.…”