ORNL, Oak Ridge, Tennessee, USA
ORNL RAD, Oak Ridge, Tennessee, USA
Recently, a high-efficiency laser assisted hydrogen ion (H−) beam stripping was successfully carried out in the Spallation Neutron Source (SNS) accelerator. The experiment was not only an important step toward foil-less H− stripping for charge exchange injection, it also served as a first example of using megawatt ultraviolet (UV) laser in an operational high power proton accelerator facility. This talk reports the design, implementation, and commissioning results of the macropulse laser system, laser transport line, and laser operation for the laser stripping experiment. The macropulse laser consists of a mode-locked picosecond pulsed seed laser and a burst-mode Nd:YAG laser amplifier. The general design concept can be adapted to any temporal beam structures in most accelerators. We have achieved UV pulses with the pulse widths varying between 34 to 54 ps and a maximum peak power over 3.5 MW. A laser transport line is installed to deliver the UV beam to the laser stripping chamber at a transmission efficiency of 70%. Laser operation including remote control and monitor of laser parameters will be described.
ORNL, Oak Ridge, Tennessee, USA
ORNL RAD, Oak Ridge, Tennessee, USA
SNS injector uses a four-vane 402.5MHz RFQ for accelerating the H− beam with 38mA peak current and 7% duty factor to 2.5MeV. The original RFQ, commissioned in 2002, has been able to support SNS operation up to the design average beam power of 1.4MW. However, several problems have developed over almost fifteen years of operation. A new RFQ with design changes addressing the known problems has been built and commissioned up to the design beam power at the new SNS Beam Test Facility (BTF). The BTF consists of a 65 keV H− ion source, a 2.5MeV RFQ, a beam line with advanced transverse and longitudinal beam diagnostics and a 6 kW beam dump. This presentation provides results of the RFQ commissioning and the BTF beam instrumentation commissioning. We also discuss progress of the ongoing multidimensional phase space characterization experiment and future beam dynamics study planned at the SNS BTF.