The Proton Storage Ring (PSR) of LANSCE compresses the pulse of a linac-produced beam by a factor of more than 2000 into an ultra-short high intensity beam, making the Lujan Center a leading facilities in the delivery of instantaneous beam power. This short-pulse feature allows a variety of experiments from neutron science to fundamental nuclear physics. Further shortening the beam pulse by another factor of 2 is necessary to achieve high-resolution nuclear data the search for Beyond Standard Model particles. We will report on our current status in our research to simultaneously stack two shorter pulses into the PSR by repurposing existing components in a system that, unlike synchrotrons, has limited flexibility.

The Los Alamos Neutron Science Center’s proton storage ring (PSR) extraction kicker systems consist of two thyratron switched blumlein modulators. The operating parameters of the PSR have changed over the years and the flattop voltage of the modulator outputs has become a limiting factor in the length of the beam pulse able to be extracted from the ring. The extraction voltage pulse travels upstream relative to the beam and thus needs to be longer than the beam pulse. A reanalysis of the voltage waveforms and the beam propagation times revealed that a longer pulse could reduce beam spill levels that have been seen during past run cycles. Reduced spill will allow operation at higher beam currents and thus increase the amount of beam current available for experimenters. We have upgraded the blumlein cables in both extraction kicker modulators with longer cables. We present test results of the modulator outputs and correlate their improvement with reduced beam losses at the PSR exit septum and improved beam delivery. LA-UR-22-21024

Abstract As part of the modernization of the Los Alamos Neu-tron Science Center (LANSCE), a digital low level RF (LLRF) control system for the LANSCE proton storage ring (PSR) is designed. The LLRF control system is im-plemented on a Field Programmable Gate Array (FPGA). The high resolution tunable 2.8MHz reference RF is gen-erated by a direct digital synthesizer (DDS) at the LANSCE front end and is transmitted to the PSR control system located half mile away. Since the digital LLRF control system is synthesized in the In-phase/Quadrature (I/Q) coordinate, the I/Q RF signals are generated by the Hilbert Transformer (HT) based finite impulse response (FIR) filter. For the stabilization of the cavity field, a Proportional-Integral (PI) feedback controller is imple-mented. In order to verify the performance of the LLRF control system before it is applied to the PSR, a FPGA based PSR cavity simulator is designed and its parame-ters are identified using the cavity field data obtained during the PSR beam operation. The low power LLRF testbench based on the simulator is constructed and the amplitude and phase stabilities of the digital LLRF sys-tem are verified.