Calibration of Langmuir probes against microwaves and plasma oscillation probes
نویسندگان
چکیده
The use of Langmuir probes for measuring plasma density is subject to uncertainty because the theories commonly used to interpret the data give widely differing results. This is especially troublesome in partially ionized plasmas used, for instance, in the semiconductor industry, since no existing theory adequately treats the case when there are a few collisions between ions and neutral atoms. In this work, plasma densities measured by microwave interferometry and plasma-oscillation probes are compared with those from probe data analyzed with Langmuir’s orbital motion limited (OML) theory, the Allen–Boyd–Reynolds (ABR) theory and the Bernstein–Rabinowitz–Laframboise (BRL) theory. It is found that ABR underestimates and BRL overestimates the density, the problems being the neglect of ion orbiting in ABR and the effect of ion-neutral collisions in BRL. The best theory is either OML or the geometric mean between the ABR and BRL results. For thicker probes, other methods are suggested. (Some figures may appear in colour only in the online journal)
منابع مشابه
Low Temperature Plasma Technology Laboratory CALIBRATION OF LANGMUIR PROBES AGAINST MICROWAVES AND PLASMA OSCILLATION PROBES
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