TY - JOUR
T1 - Effective collecting area of a cylindrical Langmuir probe in magnetized plasma
AU - Usoltceva, Mariia
AU - Faudot, Eric
AU - Devaux, Stéphane
AU - Heuraux, Stéphane
AU - Ledig, Jordan
AU - Zadvitskiy, Georgiy V.
AU - Ochoukov, Roman
AU - Crombé, Kristel
AU - Noterdaeme, Jean Marie
N1 - Publisher Copyright:
© 2018 EURATOM.
PY - 2018/6/1
Y1 - 2018/6/1
N2 - Langmuir probe diagnostic on magnetic plasma devices often encounters more challenges in data processing than in non-magnetized plasmas, the latest itself being far from simple. In this paper, a theory of particle collection by a probe at the plasma potential in collisionless weakly ionized plasmas is constructed, accounting for velocities distributed according to the Maxwell equation and different mechanisms of particle collection depending on their speed. Experimental validation of the presented theory has been done with 2 cylindrical probes (rpr = 75 μm and Lpr = 1 cm and rpr = 0.5 mm and Lpr = 1 cm) parallel to B → on a linear plasma device Aline, with magnetic fields of 0.0024-0.1 T and plasma densities of 1015-1017 m-3 in helium. Cylindrical probe measurements are compared to data from a planar probe perpendicular to the magnetic field, and the results for electron density, temperature, and plasma potential are presented. The introduced theory is initially constructed for a cylindrical probe but is applicable to various probe sizes, shapes, and orientations. Alongside the main subject, a number of associated issues are addressed with different details: a probe design issue relative to the magnetized environment, the "intersection" method of plasma potential evaluation, and the robustness of the conventional "1st derivative" method, a current bump near the plasma potential, lower limit for electron temperature estimation, and self-consistent calculation of electron temperature and density.
AB - Langmuir probe diagnostic on magnetic plasma devices often encounters more challenges in data processing than in non-magnetized plasmas, the latest itself being far from simple. In this paper, a theory of particle collection by a probe at the plasma potential in collisionless weakly ionized plasmas is constructed, accounting for velocities distributed according to the Maxwell equation and different mechanisms of particle collection depending on their speed. Experimental validation of the presented theory has been done with 2 cylindrical probes (rpr = 75 μm and Lpr = 1 cm and rpr = 0.5 mm and Lpr = 1 cm) parallel to B → on a linear plasma device Aline, with magnetic fields of 0.0024-0.1 T and plasma densities of 1015-1017 m-3 in helium. Cylindrical probe measurements are compared to data from a planar probe perpendicular to the magnetic field, and the results for electron density, temperature, and plasma potential are presented. The introduced theory is initially constructed for a cylindrical probe but is applicable to various probe sizes, shapes, and orientations. Alongside the main subject, a number of associated issues are addressed with different details: a probe design issue relative to the magnetized environment, the "intersection" method of plasma potential evaluation, and the robustness of the conventional "1st derivative" method, a current bump near the plasma potential, lower limit for electron temperature estimation, and self-consistent calculation of electron temperature and density.
UR - http://www.scopus.com/inward/record.url?scp=85048669182&partnerID=8YFLogxK
U2 - 10.1063/1.5028267
DO - 10.1063/1.5028267
M3 - Article
AN - SCOPUS:85048669182
SN - 1070-664X
VL - 25
JO - Physics of Plasmas
JF - Physics of Plasmas
IS - 6
M1 - 063518
ER -