GB913469A - Improvements in or relating to thermonuclear plasma apparatus - Google Patents

Abstract

913,469. Ion sources. COMMISSARIAT A L'ENERGIE ATOMIQUE. April 19, 1960 [April 20, 1959], No. 13651/60. Class 39 (1). A thermonuclear plasma device consists of an annular ion source 18 and an annular accelerating electrode 19 for injecting the ion beam in sheet form into the plasma chamber 4, the plasma confining coils 5, 6 being so arranged that the ions pass successively through two regions of opposite magnetic polarity and so that the magnetic flux is substantially zero at the ion source. The plasma confining magnetic coils 5, 6 provide a field of axial symmetry in the region of injection and are surrounded by a ferromagnetic frame 26 which is provided with an annular gap 27 for the passage of the ion beam. An auxiliary accelerating electrode 33 is supported by the ferromagnetic frame 26. The plasma is generated within the chamber 4 by an arc discharge between electrodes 11 and 12. Cooling channels are provided for the plasma chamber and for the magnetic coils. The ion source 18 and accelerating electrode 19 are supported by a plurality of insulators 20. The ion source emits molecular ions which are dissociated into atomic ions in the plasma. The ion source accelerating voltage may be given a saw-tooth waveform in order to turn back ions which pass through the plasma without being dissociated. Alternatively, the ions may be injected as a conical beam at an angle to the axis of symmetry of the system. The ions are injected into a weak part of the magnetic field and move into a region where the field is relatively strong. The zones of weak and strong magnetic field may be obtained by the use of magnetic shunts or by providing extra magnetic coils which produce a reverse magnetic field over a part of the confining magnetic field region. The conical ion beam may be obtained by displacement of the insulators supporting the ion source and the accelerating electrode or the supporting electrical connections within the insulators or the ion source elements may be suitably located to form the conical sheet beam. In another embodiment, Fig. 10, the annular ion source 49 is associated with a distributed system of accelerating electrodes 50. The ion source may be, e.g. a high-frequency source or an arc source.