Citation
Sanmartín Losada, Juan Ramón
(1972).
Ion-temperature-sensitive effect in transient langmuir probe response.
"Physics of Fluids", v. 15
(n. 3);
pp. 391-401.
ISSN 0031-9171.
Abstract
A theory is presented for a method, recently proposed by Hester and Sonin, of determining the ion temperature in a plasma by measuring the transient current to a cylindrical Langmuir probe after applying a potential Vp{ — eVpy>KTe) under conditions where collection is collision free and the ratio of probe radius to Debye length is small. The ion component of the current does not approach its final steady-state value monotonicalfy, but exhibits a strong, ion-temperature-dependent overshoot in the first few ion-plasma
periods following the biasing of the probe. Analytical formulas are derived for the case of a Maxwellian
plasma, and convenient graphical results are presented. The possible masking of the overshoot by a transient
displacement current is discussed; it is shown how to avoid such displacement effects. For the overshoot to be sensitive to the ion temperature T the probe must be near plasma (zero) potential before applying V1,(eVp~<0.lKTe, VP~ being that initial potential); this is not a drawback of the method, but, on the contrary, it can be used to accurately determine plasma potential along with T.