Pulsed operation of spherically convergent beam fusion device

Summary form only given, as follows. Experimental results of spherical glow discharge for a portable neutron source will be presented. An experimental device is made of 45-cm diameter, 31-cm high stainless steel cylindrical chamber, in which a spherical mesh-type anode of 30-cm diameter is installed. An open spherical grid cathode of 7-cm diameter, which is made of 1.2-mm diameter stainless steel wire, is set at the center of the spherical anode. The system is maintained at a constant pressure of 1-15 mTorr by feeding deuterium gas. By a steady-state dc operation of the device, neutron production of 10/sup 4/ s/sup -1/ was observed at a discharge of 40 kV, 2 mA. It was also shown that the neutron production rate increases with discharge current to the power of about 1.3 in low current region of several mA and is thought to be proportional to the square of current in higher current region. Therefore, using the high current region positively, neutrons can be generated much mote efficiently, However, it is difficult to get a power supply with sufficient capacity to keep high discharge current stationary. Moreover, flowing high dc current leads to overheating of the cathode. In order to prevent the cathode from overheating, pulsed high current was superposed on small dc discharge current for efficient neutron production. It was confirmed that a repetitive pulsed operation generates more neutrons than a steady-state dc operation at the same input power.