1 - Nuclear Sciences and Applications - IAEA

,oV
10
10'
10
IAEA-CN-50/A-IV-3 243
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4 6
10
dBr
6z
(G-cm ')
FIG. 3. Dependence of increase in vertical instability on — dBJdz: 1: without passive stabilization;
2: with stabilizing coil only; 3: with chamber only; 4: with chamber and coil (Ip = 100 kA).
cally unstable at the start and for R > 106 cm it is horizontally unstable. Stable
equilibrium is only possible within a narrow zone near R « 106 cm. The short time
constant of the chamber requires a fast and powerful control system for the major
radius equilibrium. At the end of December 1987, the TSP device was mounted and
pumped out down to 10" 4 Pa. By that time, only one flywheel generator had been
mounted and started up so that the device could only operate in rather poor
conditions. Therefore, to increase the discharge frequency, we used condenser
batteries as a power supply rather than the flywheel generator. For rather low toroidal
fields (about 0.2 T on the radius of 106 cm, 0.8 T on the winding) a breakdown and
a current of up to 10 kA for one-turn voltages of less than 30 V and an initial
deuterium pressure of 10~ 2 Pa were obtained. Measurements of the vertical
magnetic field distributions and current distributions in the chamber were conducted;
they showed good agreement with the calculations. Besides, an appreciable radial
component of the magnetic field of several gauss, subject to compensation, was
found. Equilibrium control system tests have shown that the required fast action is
not ensured and the column cannot be maintained in equilibrium in the chamber,
which has, according to the measurements, a time constant of about 100 s. If this
system is to be upgraded to design parameters, it has to be modified significantly,