Simulating ionospheric plasma with a hollow cathode in a large vacuum chamber

A plasma environment closely approximating the ionosphere can be generated by a hollow cathode assembly in a large vacuum chamber. This capability all ows examinations of ionospheric-plasma phenomena in a controlled setting wi thout, in most cases, relying on scaling techniques. The hollow cathode pro vides a low-temperature, low-density, fairly uniform plasma in its far fiel d, and the large chamber provides ample room such that the effects of plasm a confinement are reduced to a minimum. Most previous studies of hollow cat hodes have concentrated on their plasma environment in the near field, i.e. , within a few tens of centimeters. This work, however, examines their farf ield plasma environment, i.e., 1-2m. This characterization shows that the h ollow cathode provides, in the far field, a fairly uniform ionospheric-leve l plasma environment. The hollow cathode was operated at nine different ope rating conditions consisting of three different gases (argon, krypton, and xenon) each at three different flow rates. Results from these nine operatin g conditions are summarized, and the corresponding far-field plasma environ ments are analyzed. Comparison of the hollow cathode's plasma environment p arameters with typical ionospheric values is presented. Uses of the facilit y, such as full-scale scientific instrument verification, are presented.