Ion collection by cylindrical Langmuir probes in a strong axial magnetic field

Abstract

Cylindrical Langmuir probes were used to obtain information from a potassium plasma generated in a single-ended Q-machine. The results showed the variation of probe current ip with magnetic field strength B and were compared with the predictions of a collisionless theory. The best agreement was obtained at low plasma densities (similar 1014 m−3) when utilizing a sheath thickness which was dependent upon the dimensionless parameters ξ=rp/λp and η=ϵϕ/kT. Poorer agreement was observed in the density region above similar 1016 m−3 and was attributed to the collisionless assumption. The effects of variation in probe bias and probe size were in keeping with the theoretical predictions.Calculation of the plasma density was obtained by an iterative method and compared favourably with predictions from Laframboise's results.

Comparative study on the effects of ion density and ion energy on diamond-like carbon deposited by electron cyclotron resonance chemical vapor deposition

“…The probe was placed perpendicular to the magnetic flux to minimize the influence of magnetic field on the probe reading. 9 An optical emission spectrometer ͑OES͒ system was used to measure the light spectrum emitted by the plasma via a view port at the side of the deposition chamber. The emitted light was collected using an optical fiber coupled to a monochromator in the OES system.…”

Modeling and analysis of hydrogen–methane plasma in electron cyclotron resonance chemical vapor deposition of diamond-like carbon

“…The probe was placed perpendicular to the magnetic flux to minimize the influence of magnetic field on the probe reading. 6 ͑I-V͒ characteristics of the Langmuir probe measurements, the first approximation of electron energy KT e , plasma potential V p , and electron density n e were calculated using the simple probe theory. Subsequently, these estimated values are used to obtain more precise values of n e , ion density n i , V p , KT e , and floating potential V f using Laframboise theory.…”