Theory of a cylindrical Langmuir probe parallel to the magnetic field and its calibration with interferometry

M. Usoltceva (1, 2, 3) , E. Faudot (1) , J. Ledig (1) , S. Devaux (1) , S. Heuraux (1) , G. V Zadvitskiy (1, 4) , R. Ochoukov (3) , J. Moritz (1) , K. Crombé (5, 2) , J-M Noterdaeme (3, 2)

1 IJL - Institut Jean Lamour
2 UGENT - Universiteit Gent = Ghent University
3 IPP - Max-Planck-Institut für Plasmaphysik [Garching]
4 IGVP - Institute of Interfacial Process Engineering and Plasma Technology
5 LPP ERM KMS - Laboratoire de physique des plasmas de l'ERM, Laboratorium voor plasmafysica van de KMS

A theory for data interpretation is presented for a cylindrical Langmuir probe in plasma parallel to the magnetic field direction. The theory is tested in a linear low-temperature plasma device Aline, in a capacitive radio-frequency (RF) discharge. The probe is placed on a 3D manipulator and a position scan is performed. To exclude strong RF perturbations the probe is RF compensated. Using the theory electron densities are obtained from the current at the plasma potential, where no sheath is present. Results are calibrated by line-integrated density measurements of a 26.5 GHz microwave interferometer. Reasonable agreement is observed for probe and interferometer measurements. Furthermore, preceding, more general probe theory is compared to the one developed in the current work and the application limits are discussed.

Domaines: Physique des plasmas [physics.plasm-ph]

M. Usoltceva, E. Faudot, J. Ledig, S. Devaux, S. Heuraux, et al.. Theory of a cylindrical Langmuir probe parallel to the magnetic field and its calibration with interferometry. Review of Scientific Instruments, 2018, 89 (10), pp.10J124. ⟨10.1063/1.5038666⟩. ⟨hal-02171991⟩