High-dose Neutron Generation From Plasma Ion implantation

A reliable neutron source is needed for various applications, including calibration, detection and radiography. Particularly, there is an on-going worldwide effort in development of a high-intensity neutron source for neutron radiography of material surfaces or of bulk objects. Plasma focus machines in many institutes have been successfully demonstrated as intense neutron sources, where the neutrons are emitted from D-D or D-T thermonuclear fusion. These focus devices produce high neutron yield per shot and provide well localized point source, which is very important in neutron radiography. In order to make the neutron radiography more practical and popular, we must minimize the radiation hazards, and construction and operation costs of the neutron source. This source must be also easily movable and be reliable. Although the plasma focus devices may satisfy some of these conditions, they are still very bulky and unreliable, which are typical characters of high-power, short-pulse devices. We therefore propose a new high-dose neutron source, which makes use of the plasma ion implantation. A cylindrical palladium rod saturated by deuterium atoms is immersed in a deuterium or tritium plasma contained by a grounded cylindrical chamber. Based on a theoretical estimation, a simple new scheme to generate high-dose, steady-state neutrons is presented. This new high-dose neutron source makes use of the plasma ion implantation, which consists of a cylindrical palladium rod saturated with deuterium atoms and immersed in a deuterium or tritium plasma. The plasma is contained by a grounded conducting chamber. The palladium rod is connected to a high-power modulator, which provides a series of negative-voltage pulses. During these negative pulses, deuterium or tritium ions fall into the palladium rod and collide with the deuterium atoms in it, initiating fusion reactions and emitting neutrons. This neutron device will be portable, very reliable and almost free from radiation hazards except of the neutrons themselves. For reasonable system parameters allowed by present technology, we find from a theoretical calculation that the average neutron production rate
= 2.3 x 10¹² sec^-1 for D-T reaction, which may be more than enough for most applications. The average neutron production rate for D-D reaction is two order of magnitude less than that for D-T reaction.