ORNL, Oak Ridge, Tennessee, USA
Realization of high efficiency laser stripping at the SNS accelerator needs good longitudinal overlap between H− bunch and laser pulse. The default H− bunch length at the interaction point is 5 times bigger than needed in order to achieve 90% stripping efficiency. Theoretical and experimental studies of longitudinal H− bunch shortening are presented in this paper.
ORNL, Oak Ridge, Tennessee, USA
UTK, Knoxville, Tennessee, USA
Fermilab, Batavia, Illinois, USA
ORNL RAD, Oak Ridge, Tennessee, USA
KEK, Ibaraki, Japan
The concept of laser-assisted H− stripping, originated over three decades ago, was successfully demonstrated for a 6 ns, 900 MeV H− beam in 2006. Plans are underway to build on this foundation by performing laser-assisted H− stripping of a 10 μs, 1 GeV H− beam at the Spallation Neutron Source facility; this constitutes a three orders of magnitude improvement over the initial proof of principle demonstration. The central theme of the experiment is the reduction of the required laser power through ion beam manipulations and laser-ion beam temporal matching. This paper discusses the configuration of the experiment, the current and anticipated challenges, and the schedule.
ORNL, Oak Ridge, Tennessee, USA
The Spallation Neutron Source (SNS) accelerator complex utilizes charge-exchange injection to stack a high-intensity proton beam in the accumulator ring for short-pulse neutron production. A foil-less charge exchange injection method was researched at SNS by using a laser assisted H− beam stripping scheme. Following a proof-of-principle experiment using a Q-switched laser, a new experiment is being prepared to demonstrate laser stripping over a 10-us macropulse. In this talk, we will report the design and measurement results of the laser system for the next stage laser stripping experiment. The laser system adopts a master oscillator power amplifier (MOPA) configuration and contains an actively mode-locked fiber seeder, macropulse generator, multiple-stage Nd:YAG amplifiers, harmonic converters, and control electronics. The laser system generates 50 ps/402.5 MHz pulses (at a macropulse mode) with multiple megawatt peak power at a wavelength of 355 nm. The measurement results of laser pulse width, spectrum, spatial/temporal beam quality and their parameter dependence will be described.