PECULIARITIES OF THE START-UP PROCESS IN A TOROIDAL EXTRAP
The breakdown, occurring in the EXTRAP system, in which a plasma is immersed in the purely poloidal, strongly inhomogeneous external magnetic field, is analyzed. The division into four subsequent phases of the development of these discharges is presented. It is shown that the toroidicity, the lack of electrodes and the external magnetic field strongly affects the breakdown conditions. It is emphasized that, in the presence of the external magnetic field, the internal radial electric field has to be taken into account. Two different options for the start-up scenario are described. The discharge might either develop along the O-line or at the periphery of the discharge. The essential parameters which govern the development are shown to be the skin depth in the breakdown phase and the degree of the magnetization. The advantages and the disadvantages of these different scenarios are listed. It is pointed out that if the discharge starts along the O-line the ionization might be full only in the close vicinity of this line. Methods to improve the axial homogeneity during the breakdown phase are described.
Bibliographic Reference: WRITE TO THE DEPARTMENT OF PLASMA PHYSICS AND FUSION RESEARCH, ROYAL INSTITUTE OF TECHNOLOGY, S-100 44 STOCKHOLM (SWEDEN), MENTIONING REPORT TRITA-PFU-86-08, 1986
Record Number: 1989125021600 / Last updated on: 1987-02-01
Available languages: en