Effect of a Magnetic Field upon the Saturation Electron Current of an Electrostatic Probe

Abstract

Some experiments are performed in several kinds of discharged plasma to investigate the influence of a magnetic field upon the saturation electron current of an electrostatic probe. The apparent electron density N e ' and the positive ion density N + are calculated from the saturation electron current and the positive ion saturation current respectively and the ratio N e '/N + is plotted against ωτ (ω: the angular cyclotron frequency of electrons, τ: the mean collision time between electrons and molecules). The curve is found to show a clear dependence on the gas pressure, and when the ratio is log -log plotted against the magnetic field, it gives a nearly straight line, showing N e '/N + to be 0.1 at about 1,000 gauss. Since the positive ion saturation current is hardly influenced by the magnetic field of the order of several kilogauss, it is apparent that these properties are based upon the behavior of the electrons around the probe. A theory developed by Bohm and others is applied here to explain the experimental results.

The Effect of Rotating Cylindrical Langmuir Probes in Magnetron Plasmas

“…To try to understand our results, and in particular predict the electron current attenuation with probe-B-field angle, θ, we shall use a simple expression [14] for the current collection to the probe end and barrel and adapt it for a cylindrical probe of finite length at an angle θ. In general…”

“…It is worth noting that in the limit of d < r p , the result in [14] for cylindrical probes parallel to the field reduces to that for a plane probe parallel to the field.…”

Application of sheet shaped plasma supplemented with radio frequency plasma source for production of thin films

“…We should note that in the plasma immersed in the magnetic field, the accuracy of the Langmuir probe measurement might have some arguments, since the magnetic field restricts the electron current collection on the probe current, and nonuniformity takes place depending on the probe surface direction to the magnetic field lines. 18,19 Since the electrons have a cyclotron motion in the magnetic field, the electron current to the probe decreases with the increase of the magnetic field strength when the probe sur- face is set perpendicular to the magnetic field lines. Therefore, the electron temperature might not be correct in this situation ͑perpendicular temperature͒.…”

Collisional diffusion of a partially-ionized plasma in a magnetic field

“…Отличительной особенностью такой характеристики является наличие плато -в определенном интер-вале значений φ ρ на зонд текут практически оба тока насыщения. Ширина *) Сходный немонотонный профиль потенциала для случая зонда в полностью ионизованной плазме получен в работе Санмартина 133 .…”