Intense 14 MeV neutron source using a spherical drive-in target

A 14 MeV neutron radiation test facility using a drive-in spherical-shell target is discussed. This concept is based on a modest extrapolation of the present ion source technology and the drive-in target principle. Beams of equally mixed deuterons and tritons from four ion sources are driven into a spherical target (diameter approximately 20 cm) from all directions. The inside of the spherical shell is accessible through two ducts for neutron irradiation samples, providing a large irradiation space with no significant variation in neutron flux densities. The expected neutron source intensity at the shell is S greater than or equal to 2 x 1012 n/cm2 sec for a 300 keV-15 mA/cm2, D-T mixed beam on a titanium target. The neutron flux obtained inside the shell increases monotonically with the radial distance from the minimum phi = S at r = 0 to, for instance, phi = 1.65 S at r = 0.9 a, where an is the radius of the spherical shell. This facility has a unique advantage in that a number of irradiation experiments can be performed simultaneously and a fairly uniform neutron flux can be obtained over an irradiation sample of large size. The target is designed to handle 4-5 kW/cm2 of beam power by utilizing a ''shell'' of vortex-flow generators. D-T mixed gas is continuously recirculated and the target plating is done in-situ. Preliminary design ideas will be discussed