Measurements of argon metastable species in an electron beam generated plasma

Electron beam (e-beam) generated plasmas show promise for their use in the processing of materials by enabling control over the electron energy while maintaining a low electron temperature [1]. In this work, we used laser induced fluorescence (LIF) to measure the argon metastable Ar (1s₅) density in a partially magnetized ExB argon plasma produced by a keV-range e-beam in the pressure range of 25-90 mtorr. Langmuir probe measurements were made to obtain the electron temperature and density. The Ar (1s₅) metastable density increased with pressure and was in the range of (3-8) x 10¹⁶ m^-3 in the core of the discharge. We will discuss this effect of the argon pressure and physical mechanisms governing the measured spatial distribution of the argon metastable.

[1] S. G. Walton et al., ECS Journal of Solid State Science and Technology, 4(6), N5033 (2015).