Fundamental study of radially convergent beam fusion

Abstract

Summary form only given, as follows. Previous studies of spherically convergent beam fusion (SCBF) indicate that it has a potential applicable to a portable neutron source. However, the detailed mechanism of SCBF has not been made clear. This depends on a fact that it is difficult to measure the physical quantities precisely in a central region of spherical configuration. Therefore, we devised to change the electrodes shapes from spherical to cylindrical. This alteration eases precise measurements and diagnoses because of the better axial uniformity. In the study, experimental results of cylindrical glow discharge for a portable neutron source are presented. An experimental device is made of 45 cm diameter, 31 cm high stainless steel cylindrical chamber, in which a cylindrical mesh-type anode of 16 cm diameter, 31 cm high is installed. An open cylindrical grid cathode of 5 cm diameter, 27 cm high, which is made of 2.0 mm diameter stainless steel rod, is set on the axis of the cylindrical anode. The system is maintained at a constant pressure of 1-15 mTorr by feeding hydrogen or deuterium gas. Basic discharge characteristics, such as breakdown voltage versus pressure, operating voltage versus discharge current with changing gas pressure and floating potential profiles, were measured for hydrogen discharge. Using deuterium gas, neutron production rate was also measured changing the operating voltage and discharge current. The results indicate that beam-background reactions are dominant in the measured range of voltage and current.