Diffuse vacuum arc with heated cathode made of ceramic (CeO₂) and metal (Cr) mixture

Abstract

The paper presents a diffuse vacuum arc with heated cathode made of ceramic (CeO 2 ) and metal (Cr) mixture, initiated and studied for the first time. Plasma sources of multicomponent mixtures are demanded for plasma based methods of rare-earths recycling and spent nuclear fuel reprocessing, which are currently under development. The discharge current-voltage characteristic was measured for different cathode temperatures (1950-2250 K); in the range of the arc current 30-100 A the voltage varied from 6 to 11 V. A cooling effect of the mixed cathode due to the thermionic emission at presence of the arc plasma was found; the effect reached about 150 W at the arc current of 30 A. The cooling effect and the current-voltage characteristic distinguish the discharge from the diffuse vacuum arcs with single-component cathodes made of cerium dioxide and chromium. The plasma parameters and optical emission spectra were analyzed for various cathode temperatures and arc currents (electron temperature was 0.4-0.6 eV, local particle densities in plasma near the cathode were in range 10 11 -10 13 cm −3 ). The study is of interest for plasma sources development and increase of their efficiency as well as for the tasks aimed at ionization of multicomponent mixtures.

Diffuse vacuum arc discharge with heated cathode made of mixture of ceramic and metal powders

“…Due to the high temperature of the cathode (~2000 K), it is possible to provide conditions for the arc current conduction, to stabilize the discharge voltage fluctuations, and to decrease droplet fraction in the plasma flow. Previously, such a discharge has already been studied partially on a cathode made of a mixture of cerium dioxide powder and chromium flakes [2], and its promise as an efficient plasma generator was shown.…”

Plasma mass separation in configuration with potential well

“…In the work [39,40] a regime was found in the gadolinium cathode in which plasma with mainly singly charged ions is realized behind the anode, and the average charge is close to unity. Cathodes made of Pb [41] and CeO 2 + Cr mixture [42,43] were also investigated under similar conditions. The disadvantage of this method of converting solid to plasma is that the crucible with the melt must be oriented vertically; otherwise, the melt can spill out.…”

Role of thermionic emission in the formation of negative electric potential and oscillations in low pressure discharges

“…For example, Amirov et al [12] developed a diffusive vacuum arc where the nonthermionic lead cathode was used. Usmanov et al [13] studied a diffuse vacuum arc with a heated cathode made of ceramic (CeO 2 ) and metal (Cr) mixture.…”