Comparison of glow, arc, and magnetron direct current discharges

Abstract

Glow discharge (GD) in a tube, arc discharge (AD) without cathode heating from an external source, and magnetron discharge (MD) in a planar magnetron are compared. In each of the discharges, characteristic areas are distinguished. In MD, electrons trapped in the near-cathode region are not directly involved in ionization processes, but “wake” acceleration of slow ions by electrons that move along Larmor orbits is possible, which gives additional energy to ions moving toward the cathode. In GD in the near-cathode region, the average energy of the ejected electrons is on the order of several electron volts, and the energy of the ions and neutrals is less than 0.1 eV. In MD in the near-cathode region, the average energy of knocked-out electrons, ions, and neutrals is on the order of tens of electron volts. The differential resistance of GD is negative, that of AD is usually negative, and that of MD is positive. The energy of ions in the magnetron plasma can be greater than that of electrons, which gives new possibilities for acoustoplasma control of MD and the creation of appropriate instruments and devices.