LECTURES ON THE HYDROMAGNETIC STABILITY OF A CYLINDRICAL PLASMA. VI. POSSIBLE INFLUENCE OF PARTICLE MOTIONS ACROSS THE LINES OF FORCE
It has recently been shown by Rosenbluth and Suydam that the stabilized pinch may suffer from surface instabilities. These arise because, in a discharge with a current layer of finite thickness, perturbations can arise which affect the outer surface of the current layer but leave the inner surface unperturbed. For such perturbations the trapped axial field exerts little stabilizing influence. These surface instabilities are of a very localized character and rapidly enter a nonlinear phase. In deriving these results it was assumed that the plasma is an ideal hydromagnetic fluid, which implies that particles are tied to the lines of magnetic force. In an actual plasma particles can move across lines of force in performing Larmor orbits and, in the case of surface instabilities, the distance moved may be comparable with the scale of the perturbation. If this is so the particles may exert a stabilizing influence. Some recent calculations by Hubbard, discussed in this lecture, suggest that these particle motions do have an important effect on stability. It would be very difficult to solve the full stability problem with panticle motions introduced. Instead, Hubband assumed that any particle is acted on by an average magmetic field, and by performing a suitable average he removed the singularity in the Euler-Lagramge equation. It was then found for a typical example that the discharge remains stable until the current layer has a thickness of about 20% of that of the discharge. Results are based on physical intuition rather than on mathematical rigor. (auth)
- Research Organization:
- United Kingdom Atomic Energy Authority. Research Group. Atomic Energy Research Establishment, Harwell, Berks, England
- NSA Number:
- NSA-13-022173
- OSTI ID:
- 4232297
- Report Number(s):
- AERE-L-107
- Country of Publication:
- United Kingdom
- Language:
- English
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