RF plasma probe diagnostics: a method of eliminating measurement errors for Langmuir probes with bare protective shieldsстатья
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Дата последнего поиска статьи во внешних источниках: 6 февраля 2020 г.
Аннотация:This work demonstrates the measurement errors for probe diagnostics in
radio-frequency (RF) plasma using Langmuir probes that have bare protective
shields and the way of their eliminations. The parameters of xenon inductive
plasma were measured with two different in forms and locations cylindrical
Langmuir probes that had reference probes and bare protective shields. Accurate
probe diagnostics using an advanced probe station VGPS-12 featuring precise
determination of plasma electron energy distribution functions (EEDFs) and
plasma parameters enabled effective quantitative evaluations of EEDF deviations
from the Maxwell function. They were considered to be EEDF distortions that
linearly depended on the lengths of the probe’s protective shields and were
minimal for one of the probes when its shield’s length was zero in the special point
of the discharge space. Comparison of measurement data in this special point
identified the principled relationship between measurement errors and EEDF
distortions, which enabled correction of all measured plasma parameters using
previously determined radial distributions of individual EEDF distortions. In the
present work a method has been proposed that describes all these actions. In
addition, consideration of plasma-shield interactions showed that the physical
reason for the measurement errors was a short-circuited double-probe phenomenon
in the bare protective shields caused by longitudinal variations of plasma
potentials