Chromium, a promising cathode candidate for homogeneous arc erosion in air

Abstract

Cathode erosion hinders the development of high-power arc heaters, and the inhomogeneous erosion of the copper cathode results in catastrophic failures. In this work, the arc erosion behavior of a chromium cathode was investigated compared with copper. The former was relatively homogeneous with shallow erosion pits. The eroded microstructure suggests that the surface chromic oxide layer could suppress the formation of deep craters. The maximum erosion depth and the erosion rate of chromium were lower than those of copper. The single erosion pits on chromium gradually extended and disappeared, suggesting a reduction in the input energy flux density. The underlying mechanism for the homogeneous erosion behavior of the chromium cathode was proposed. The homogeneous erosion behavior of the chromium cathode makes it a promising candidate for high-power arc heaters.

Sustainable and homogeneous arc ablation behavior of zirconium cathodes improved by in situ formation of zirconium oxides

“…The discharge experiments were conducted in the cathode ablation testing system [14,17] both in air atmosphere and argon atmosphere. The cathode ablation system consists of a three-axis motion platform, a cooling system, a gas supply unit, a DC power source, a measurement system and a highspeed camera.…”

“…During discharge, the arc is stabilized by supplying a substantial number of electrons from the cathode surface through craters and threaten the cathode's structural integrity. Such inhomogeneous ablation processes can be suppressed by generating a surface strengthening layer with a high melting temperature [16,17].…”

Laser Cladding of Layered Ti/Nb/Cu Cathode with Homogeneous Arc Ablation Behaviors

“…[ 8 ] The arc discharge status with scattered cathode spots results in inhomogeneous cathode ablation behaviors. According to previous researches, [ 14,27 ] the ablation craters induced by cathode spots of type II would cause massive ablation loss.…”

“…Those deep ablation pits, formed due to the attaching of cathode spots, reflect the typical inhomogeneous ablation process of Cu cathodes. According to our previous researches, [ 14,27 ] the pits grow deeper with further discharging and cause degradations of the cathode discharging.…”

“…The common strategies in improving discharge homogeneity include cathode spot dispersion [18][19][20][21][22][23] and cathode spot-type regulation. [24][25][26][27] The former disperses cathode spots through alloying with low-work-function additions and grain refinement, [28,29] while the latter focuses on modifying the cathode surface to generate type I cathode spots. [30] Yuan et al [31] realized a transition from concentrated cathode spots to separated spots in Cu-0.3% Y 2 O 3 and Cu-0.3% LaB 6 cathodes.…”