Spectroscopic measurements of spherically convergent beam fusion

Summary form given only, as follows. Spherically convergent beam fusion (SCBF) is a scheme for accelerating ions, which are generated between electrodes by a glow discharge, toward the spherical center and giving rise to fusion reactions. The SCBF device is very simple and compact unlike other fusion devices. Therefore, it is applicable to a portable neutron source. However, the detailed mechanism of SCBF has not been made clear yet. The experimental device is made of 45 cm diameter and 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 is set at the center of the spherical anode. The system is maintained at a constant pressure of 0.6 to 55 mTorr by feeding discharge gas through a leak valve. The visible and ultraviolet emission from the device was investigated using hydrogen discharge. Emission, from the SCBF device is focused by a lens (f=100 mm) on an end of an optical fiber and guided to a spectrometer. The spectrometer is a Czerny-Turner type and the resolution is 0.027 nm. Effects of the discharge current and cathode voltage on emission intensities and spectrum profiles of hydrogen Balmer lines were investigated. In the case of the Star mode, the peak of emission intensities was obtained at the spherical center. The plasma core at the cathode center expanded with discharge current and shrunk with cathode voltage. All hydrogen lines were broadened with the cathode voltage. There was a good agreement between the experimental and the calculational results, and so the broadening was verified to be caused by the Doppler effect. The detailed experimental results will be presented.