|Budget Amount *help
¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1991 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1990 : ¥1,900,000 (Direct Cost : ¥1,900,000)
In order to improve the shape of high voltage pulse waveforms, which are used to generate monochromatic intense relativistic electron beams (REB), the principle of non-interferential accumulation of induction voltages was studied.
In the first year of this research, two pulse forming networks (PFN), the characteristics of them are slightly different, were made. The characteristic impedance, the maximum withstand voltage of them are 100 OMEGA and 180kV, respectively. Using a m13EA\ : agnetic switch, synchronous operation of them and the principle of accumulation of induction voltages were confirmed. However, it was found that the pulse transmission line made of lumped elements acts as a low pass filter. Therefore, when a transmi13EA\ : ssion line is designed, capacitances and inductances of them should be smaller than those of a PFN by a factor of 10.
In the second year (final year), the research was focused on the generation of intense REB by using a magnetically insulated gun. Observati
on with a plastic scintillator confirmed that the shape of the REB was annular. When a brass cathode was used, 13EA\ : the reproducibility of REB generation was not good and the obtained beam current was rather low. On the contrary, when a carbon cathode was used, good reproducibility was obtained. The maximum energy, current and duration time of the REB generated were 100 keV, 100 A and 300 ns, respectively. This is probably caused by the existence of many whiskers on the cathode surface. The value of beam current also depended on the ratio between the insulation and the guide magnetic field strengths. By a computer simulation, the cause was revealed that the trajectries of electrons were much influenced by the ratio and if the ratio is not adequate, electrons hit the anode or the tube wall. Furthermore, the experimentally obtained current was always lower than that predicted by a theory. Not only the mutual collision of electrons but also the instability, the cause of which is not identified, is maybe responsible for.
This study revealed the potential of non-interferential accumulation of induction voltages to improve the waveforms of high voltage pulses and that this principle is applicable to the generation of monochromatic intense REB. Less