Application Of Langmuir Probes Research Articles

Application of Langmuir probe and optical emission spectroscopy for bromofluorocarbon plasma diagnostics

The Langmuir probe and optical emission spectroscopy were applied for diagnostics of C2F4Br2 low-pressure inductively coupled plasma. Electron temperature, plasma potential and concentrations of electrons, and positive ions, as well as fluorine and bromine radicals, were determined. An explanation of the results of experiments on the etching of low-k dielectrics in the studied plasma was proposed.

Recommended Practice for Use of Langmuir Probes in Electric Propulsion Testing

Presented in this work is a guide to standardize the methods of performing correct and accurate Langmuir probe measurements within the plasma environment produced by an electric propulsion device. The construction, installation, operation, and data interpretation of the full family of Langmuir probes are addressed including single Langmuir probes, double Langmuir probes, and triple Langmuir probes. Traditional time-averaged operation as well as high-speed operation are discussed as are the various pressure and external field limitations of Langmuir probes. This recommended practice is established from the vast collection of preexisting Langmuir probe theory and operational experience within the plasma environment of electric propulsion thrusters. Focus is placed on the application of Langmuir probes in the most common electric propulsion devices including Hall, ion, and pulsed thrusters. These electric propulsion devices all create flowing plasmas that require special probe construction and data analysis that is not needed in many other types of plasmas where Langmuir probes are commonly employed. The recommended practices are presented in a concise handbook style, reserving all theoretical derivations and details to the referenced works of their origination.

Langmuir probe measurements of the electron energy distribution function in magnetized gas discharge plasmas

In this work, methods for using Langmuir probes (LPs) in magnetized plasmas are presented. The electron part of the current–voltage probe characteristics is used to obtain the plasma potential, the electron energy distribution function (EEDF), the electron temperature and the electron density. The application of LPs to EEDF evaluation in the presence of magnetic fields in the range 0.01–0.1 T is investigated and discussed based on kinetic theory in a non-local approach. Data for EEDFs in magnetic fields in the range 0.015–0.079 T are acquired using current–voltage characteristics measured in low pressure Ar and He dc gas discharges. It is also shown that the EEDFs are Maxwellian up to the energy of the first excited states of argon and helium. The values of the plasma potential, electron temperature and density are evaluated. Comparison of the results obtained with probes perpendicular and parallel to the magnetic field results in satisfactory agreement.The results presented demonstrate that the procedures proposed allow one to acquire the main plasma parameters using the electron part of the current–voltage LP characteristics in magnetized plasmas.

Source of a dense metal plasma

This paper presents results of experimental investigation of a low-threshold slipping surface discharge as a pulsed source of a dense metal plasma. The density of the plasma was measured by application of Langmuir probes and a microwave interferometer. Mass and energy ion spectra were determined using the ion electrostatic and magnetic analyser. Preliminary results concerning a new metal plasma source application for TiN thin-film deposition are discussed.

Absolute Electron Density Measurement Techniques in Hypersonic Wakes

New techniques have been evolved for the application of Langmuir probes to the measurement of electron densities in the wakes of hypersonic projectiles flown in ballistic ranges. These techniques concern probe cleanliness, minimization of flow disturbance, minimization of reflected shocks, and the effect of plasma potential. Electron density level estimates obtained with the probes in sphere wakes were in good agreement with electron density estimates derived from simultaneous measurements with a microwave interferometer.