Collisional instability in a rare magnetized plasma: an experimental model for magnetospheric and space plasma study

Abstract

In a suitable experimental device, laboratory plasma is produced with conditions and parameters analogous to magnetospheric plasma; we light a rare plasma in a semi-machine using rf-frequency discharge. Three ranges of lowfrequency instabilities appear, one of which is identified as drift, caused by electronneutral collisions. A full theoretical elaboration adapted to production conditions and geometrical symmetry is carried out; one solution of the dispersion relation is sufficient justification for the existence of the instability. The mathematical analysis also has the ambition to give interpretation for other low-frequency waves. Here we make a sound identification of the instability type as drift resistive due to electron-neutral collisions by an investigation of the growth rate. An agreement between experimental results and the theoretical model is obtained. As in the magnetosphere, an external magnetic field restrains the plasma.

Approximate models for the study of exponential changed quantities: Application on the plasma waves growth rate or damping

“…[27][28][29][30][31] A steady steel cylindrical cavity of 6 cm internal diameter, with its' length adaptable to any purpose, is used almost always, as it is preferable due to its' cylindrical symmetry simplicity. The argon-plasma is usually produced due to the argon atoms inertia and its' low penetration.…”

“…The study of these waves has been done theoretically 27,28,30 by using the fluid mechanics equations and their dispersion relation, as well as the growth rate and damping, have been found. Thus, three types of dispersion relations and their growth rate are mentioned here; the first dispersion relation is the following, with the growth rate, …”

“…The imaginary part of the wave circular frequency has been actually calculated via the steady state hydrodynamic equations. 27,28 On the other hand, the wave stability on the steady state demands ω i to be near zero, whence it must be considered that the extinguishing factors press for ω i → 0.…”

“…In the present work three such examples have been given, 27,28 although the purpose of our team is to shape a full list of the models, which may be useful and easy for the experimental and theoretical researchers. Thus, the completion of the model list is the immediate future work, since the experimental confirmation is the difficult part of the completed research; this difficulty is caused by the little amount of time for the growth establishment of the rising wave, whereas this amount of time is very large for the nuclear decays; for this reason the measurements must be taken very methodically.…”

The big contradiction between the perturbation theory and the chaotic state. A detailed mathematical analysis indicates when the plasma is stable or unstable

“…8 These two different plasma configurations have been studied extensively by the research team of the Plasma Laboratory of 'Demokritos'. [9][10][11][12] The study of both the plasma's stable and unstable state is easier using drift waves since they have been studied extensively in the past. Here a brief overview of these low-frequency drift waves is given.…”