Fast burst and steady-state intense neutron source

Abstract

A first system for producing a high flux of neutrons for non-destructive testing includes a dense plasma focus device neutronically coupled to a subcritical or sub-prompt critical fission assembly. The dense plasma focus device is a source of initiating neutrons for the fission assembly, and the fission assembly is configured to multiply a number of the initiating neutrons via inducing fission. A second system for producing a high flux of neutrons includes a gas-target neutron generator neutronically coupled to a subcritical or sub-prompt critical fission assembly. The gas-target neutron generator is a source of initiating neutrons for the fission assembly, and the fission assembly is configured to multiply a number of the initiating neutrons via inducing fission.

What is claimed is: 
     
         1 . A system for producing a high flux of neutrons, the system comprising:
 a dense plasma focus device having an input end and an output end, the dense plasma focus device including
 a cylindrical cathode; 
 a cylindrical anode disposed within and concentric to the cathode; 
 an insulator provided between portions of the cathode and the anode, the insulator disposed proximate to the input end of the dense plasma focus device; and 
 a chamber bounded by the cathode and the anode, the chamber being pressurized with a fill gas; and 
   a fission assembly neutronically coupled to the dense plasma focus device,   wherein the fission assembly is a subcritical or a sub-prompt critical fission assembly, and   wherein the dense plasma focus device is a source of initiating neutrons for the fission assembly, and the fission assembly is configured to multiply a number of the initiating neutrons via inducing fission.   
     
     
         2 . The system of  claim 1 , wherein the fill gas comprises a deuterium-tritium gas mixture. 
     
     
         3 . The system of  claim 1 , wherein a pressure of the fill gas is static at 1-100 Torr. 
     
     
         4 . The system of  claim 1 , wherein a pressure of the fill gas is dynamically raised at a pinch formed at a center of a tip of the anode by introducing puffs of the fill gas at pre-determined time intervals. 
     
     
         5 . The system of  claim 1 , wherein the dense plasma focus device is capable of yielding at least a 1×10 14 n/pulse. 
     
     
         6 . The system of  claim 1 , wherein the cathode has a radius of at least 20 cm and the cathode has a radius of at least 30 cm. 
     
     
         7 . The system of  claim 1 , wherein the dense plasma focus device further comprises a group of capacitor banks constructed in series, and
 wherein individual discharges of each of the capacitor banks are timed such that a specific pulse is formed in order to control a current drive time and a magnitude of current delivered to a pinch formed at a center of a tip of the anode.   
     
     
         8 . The system of  claim 1 , wherein the fission assembly comprises:
 an outer multiplier layer configured to cover sidewalls and the input end of the dense plasma focus device;   a fast neutron multiplier layer configured to cover the output end of the dense plasma focus device; and   a low enriched uranium blanket configured to bound a test cavity,   wherein the fast neutron multiplier layer is sandwiched between the output end of the dense plasma focus device and the low enriched uranium blanket.   
     
     
         9 . The system of  claim 8 , wherein the outer multiplier layer is comprised of depleted uranium metal. 
     
     
         10 . The system of  claim 8 , wherein the fast neutron multiplier layer is comprised of an aluminum-beryllium alloy. 
     
     
         11 . The system of  claim 8 , wherein the fission assembly further comprises a neutron reflector configured to surround the dense plasma focus device, the outer multiplier layer, the fast neutron multiplier layer and the low enriched uranium blanket. 
     
     
         12 . The system of  claim 11 , wherein the neutron reflector is comprised of copper. 
     
     
         13 . A system for producing a high flux of neutrons, the system comprising:
 a gas-target neutron generator including
 an ion source configured to produce an ion beam; 
 an accelerator configured to accelerate the ion beam to produce an accelerated ion beam; 
 a plurality of focus elements configured to focus the accelerated ion beam in an x-direction and a y-direction; and 
 a pumping/gas-target section including a gas target chamber filled with a target gas; and 
   a fission assembly neutronically coupled to the gas-target neutron generator,   wherein the fission assembly is a subcritical or a sub-prompt critical fission assembly,   wherein the fission assembly surrounds the gas target chamber, and   wherein the gas-target neutron generator is a source of initiating neutrons for the fission assembly, and the fission assembly is configured to multiply a number of the initiating neutrons via inducing fission.   
     
     
         14 . The system of  claim 13 , wherein the target gas of the gas-target neutron generator is comprised of either deuterium or tritium. 
     
     
         15 . The system of  claim 13 , wherein the ion beam produced by the ion source is a deuterium ion beam and the target gas is tritium gas. 
     
     
         16 . The system of  claim 15 , further comprising a tritium purification system configured to purify a mixed tritium and deuterium gas resulting from an interaction between accelerated deuterium ions and the tritium gas in the gas target chamber, and return purified tritium gas into the gas target chamber,
 wherein the tritium purification system is configured to control a neutron output of the gas-target neutron generator by controlling a percentage of tritium in the gas target chamber by controlling a flow rate of the purified tritium gas into the gas target chamber.   
     
     
         17 . The system of  claim 13 , wherein the ion source is a microwave ion source configured to produce an ion beam comprised of deuterium ions. 
     
     
         18 . The system of  claim 17 , wherein the microwave ion source is configured to operate at an extraction current of 10-200 mA. 
     
     
         19 . The system of  claim 13 , wherein the plurality of focus elements comprises a plurality of electrostatic quadrupole elements. 
     
     
         20 . The system of  claim 13 , wherein the plurality of focus elements comprises a plurality of magnetic solenoid elements. 
     
     
         21 . The system of  claim 13 , further comprising a differential pumping system configured to maintain a first pressure differential between an outside atmosphere and the accelerator, a second pressure differential between the outside atmosphere and the gas target chamber, and a third pressure differential between the accelerator and the gas target chamber.