Injection of plasma into the Trimyx Galathea

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IC CONFINEMENT SYSTEMS

Injection of Plasma into the Trimyx Galathea A. I. Morozova, A. I. Bugrovab, A. M. Bishaevb, M. V. Kozintsevab, A. S. Lipatovb, V. I. Vasil’evc, and V. M. Strunnikovc aKurchatov

Institute Russian Research Centre, pl. Kurchatova, Moscow, 123182 Russia State Institute of Radioengineering, Electronics, and Automation (Technical University), pr. Vernadskogo 78, Moscow, 117454 Russia cTroitsk Institute for Innovation and Fusion Research, Troitsk, Moscow oblast, 142190 Russia

bMoscow

Received July 5, 2005; in final form, September 5, 2005

Abstract—The Galathea-3 device, which consists of a coaxial plasma gun, a plasma guide, a lock chamber, and the Trimyx Galathea confinement system with three myxines, is briefly described. The plasma parameters at the outlet from the plasma gun, in the plasma guide, and in the confinement system are presented. It is shown that the plasma can be efficiently entrapped into the Galathea and spread out along it. The confined plasma is found to go beyond the Ohkawa surfaces. Estimates show that the particle losses from the system are on the order of the classical ones. PACS numbers: 52.55.–s, 52.55.Hc DOI: 10.1134/S1063780X06030019

1. INTRODUCTION The Galathea is a special type of magnetic confinement system in which the electric conductors (myxines) are imbedded in the plasma (see [1–6]). It is expected that, in such a system, which is intended for plasma confinement in fusion reactors, the value of β0 =

the too short distance between the separatrix and the socalled Ohkawa surfaces, defined by the conditions dl

°∫ ---B-

2

2µ0Pmax/ B max (where Pmax and Bmax are the maximum plasma pressure and the maximum magnetic field in the reactor, respectively) can be on the order of unity and plasma transport can be classical. Note that, in the existing tokamaks and stellarators, these conditions are not satisfied. Experimental and theoretical studies of multipole (quadrupole and octupole) toroidal Galatheas [7–10] showed that these beneficial properties (including classical transport) can actually be achieved. However, the investigated types of Galatheas (equilibrium in them was calculated based on the Grad–Shafranov equation [11]) have a serious disadvantage: the plasma confinement time is significantly limited because the distance δs–m between the separatrix and the myxine surface is too short. Of course, this disadvantage is not critical and can easily be overcome by proportionally increasing the dimensions of the system. However, in the initial stage of research, the limited dimensions of the available vacuum chambers motivate the search for new versions of multipole Galatheas that would have usual dimensions but in which the value of δs–m would be sufficiently large. This search led to the Trimyx configuration proposed by A.I. Morozov [12] (see Fig. 1). A disadvantage of this configuration (in the absence of plasma) is

= min,

(1‡)

°∫ dl = min.

(1b)

Here, Eqs. (1a) and (1b) define Ohkawa surfaces A (Fig. 1a, curve 6) and B (Fig. 1a, curve 7), respectively. Previ