Design and Performance of the Solid-State Laser Trigger System for HERMES III

The HERMES III accelerator is an 18-20-MeV linear induction accelerator constructed at Sandia National Laboratories in the late 1980s and which continues operation to this day. As part of recent modernization efforts, the laser triggering system on the accelerator has been replaced with a newly designed solid-state system. This system consists of ten Nd:YAG lasers, each having a nominal output energy of 40-45 mJ at a wavelength of 266 nm. The beam from each laser is split such that it triggers two of the Rimfire gas switches on the accelerator. Compared to the previous laser triggering system, this arrangement makes it possible to more readily tailor the final output pulse shape, and the overall reliability of this key accelerator system is now improved. The design of the new laser triggering system is presented here, along with details pertaining to the energy budgeting, optical beam paths, and electrical triggering of the lasers. The initial operational data from the HERMES III accelerator using this new triggering system are also presented.