Livermore intense neutron source: design concepts

The Lawrence Livermore Laboratory proposes to build an irradiation facility containing several 14 MeV T(d,n) neutron sources for materials damage experimentation. The sources will operate as a national facility for CTR materials damage studies under the auspices of the Materials and Radiation Effects Branch of the Division of Controlled Thermonuclear Research. A source strength of 4 x 1013 n/s can be produced with 400 keV D+ beam on the tritium in titanium target system now used on the Livermore Rotating Target Neutron Source (RTNS). Each accelerator will use a Cockcroft-Walton HV supply with high speed diodes, a multiple aperture ion source with pre-acceleration species selection, and a short, uniform gradient acceleration tube. The beam transport system from accelerator to target will accommodate a considerable amount of residual space charge on the 400 keV beam. Development of the 5000 rpm differentially pumped air bearing seal for the target system is complete. Prototype targets with internal water cooling have operated at 5000 rpm using this seal. Advanced target development may allow the accelerators to be upgraded to 400 mA current, providing source strengths above 1014 n/s. The neutron sources will be supported by a laboratory building providing mechanical, electronic, computer, dosimetry, and materials handling services for the users of this facility. Facility subsystems will allow rapid retrieval of experimental apparatus for sample changes and have extensive data logging capability for in-situ measurements