Conceptual design of a DC gas-discharge tube with magnetic field generated by a Helmholtz coil

Abstract This paper presents the conceptual design and construction of a DC gas-discharge tube combined with a magnetic field generated by a Helmholtz coil to study plasma parameters under magnetized conditions. The developed system consists of a seven-cathode configuration and a common anode that enables diagnostics with single electrical probes — parallel and perpendicular to the magnetic field lines. The maximum achievable magnetic field is 1000 G. The specially designed electronic system allows high-frequency and precise measurements of the current-voltage characteristics using the Langmuir probe method. The setup operates with different gasses (starting with argon) under controlled flow and low-pressure conditions. The modelling of the electron currents reveals significant differences in probe characteristics depending on their orientation to the magnetic field and on plasma parameters such as the temperature and density of the electrons. The developed device makes it possible to investigate the application of the probe methodology in plasma with magnetic field, in order to use it in various experimental devices — from magnetron discharges for advanced materials treatment technologies to fusion reactors.