Electron Density Measurements in the Magnetically Confined Arc

Abstract

Three methods were used to obtain electron density as a function of radius in a magnetically confined, low-pressure argon arc. The first utilized the phase shift of a reflected 35-kMc/sec microwave, and the second determined density from the ion saturation current to a Langmuir probe. The third determination utilized the broadening of the H β line emitted by a small quantity of added hydrogen. Agreement among the three methods is satisfactory; the electron density at the axis of this discharge is of order 1014 cm−3, in agreement with results obtained by others for discharges of similar type.

Hydromagnetic wave in an inhomogeneous cylindrical plasma

“…The density distributions were measured by means of the ion saturation current to a Langmuir probe, these having been shown to be reliable for this discharge in previous work [McLane, Takeda, Thomas, and Thompson, 1965]. For convenience in using the densities in the calculations to follow, they were graphically fit with Gaussian profiles from the axis out to 5 mm radius.…”

“…The plasma used in this investigation is that of the magnetically confined, low pressure argon arc [McLane, Takeda, Thomas, and Thompson, 1965]. For the operation of this arc, three electrodes alined with a uniform (± 3 percent) magnetic field are utilized.…”