Plasma hollow cathodes

Abstract

Hollow cathode plasma discharges are a fundamental part of a large variety of applications in industry, academia, and space. From surface processing and coatings deposition to plasma–surface interaction research and electric propulsion, advances in hollow cathode modeling and performance are critically important to the progress and evolution of these and other areas of technology. This paper describes perspectives on the progress that has been made in recent years in the capabilities and modeling of hollow cathodes used in plasma discharges. While many of the developments have been driven by the demanding requirements of electric propulsion applications, the information provided applies to all thermionic hollow cathodes and their applications. In the paper, we describe the status of 2D global simulations of hollow cathode plasmas, hollow cathode plume instabilities, and the development of higher current cathodes and low-current heaterless cathode technologies. Advances in our understanding and technology in these areas and some of the challenges that still need to be addressed and solved are discussed.

Improved Thermal and Mechanical Properties of [Ca24Al28O64]4+(4e−) Electride Ceramic by Adding Mo Metal

“…A dedicated plasma-based cathode similar to a hollow cathode has been designed to test the performance of the CerMets. Hollow cathodes are plasma sources commonly used as electron emitters in space applications [19][20][21] as well as in laboratory plasma generation processes. The dedicated design features disk-shaped inserts that can be easily exchanged to compare the characteristic of the plasma discharge with different ratios of molybdenum in the composite.…”

A Coupled 0-D Plasma Thermal Model for Hollow Cathodes

“…By solving the unsteady fluid equations along the axial and radial directions, these models are capable of investigating the plasma instabilities established in the plume region. A significant result obtained by these codes is the prediction of the onset of the so-called plume mode of operation developing inside the plume [8], [9], a well-known instability appearing when the discharge current increases or the propellant flow rate is reduced, which leads to a larger energetic ion bombardment of the keeper and orifice plate, ultimately reducing the cathode operating life. Despite these favorable advantages of 2-D models, their main setback is the computational cost and complexity of the simulation which makes them unsuitable for cathode prototyping.…”

Glow Discharge With a Hollow Cathode in Carbon Dioxide

“…Discharges with a hollow cathode are widely applied in analytical spectroscopy [1,2], gas discharge lasers [3,4], plasma technology processes of surface modification [5][6][7], ion thrusters [8,9]. Therefore a large number of papers are devoted to experimental and theoretical studies of the discharge with a hollow cathode (see e.g.…”