Engineering topics
Long, Cary D
Publications and source records attributed to Long, Cary D.
Nonintrusive Emittance Measurement of 1GeV H- Beam with a Laser
A laser wire based transverse phase space measurement system has been developed at the Spallation Neutron Source (SNS). The system allows a nonintrusive measurement of 1GeV hydrogen ion (H-) beam at the high energy beam transport (HEBT). This paper describes the design, installation, and measurement performance of the system. Major technical challenges in the implementation and commissioning of the nonintrusive phase space diagnostics at high brightness particle accelerator facilities are discussed.
DIAGNOSTIC TOOLS FOR BEAM HALO INVESTIGATION IN SNS LINAC
Uncontrolled beam loss is a major concern in the operation of a high intensity hadron linac. A low density cloud of particles with large oscillation amplitudes, so called halo, can form around the dense regular beam core. This halo can be a direct or indirect cause of beam loss. There is experimental evidence of halo growing in the SNS linac and limiting the further reduction of beam loss. A set of tools is being developed for detecting of the halo and investigating its origin and dynamics. The set includes high resolution emittance measurements in the injector, laser based emittance measurements at 1 GeV, and high resolution profile measurements along the linac. We will present our experience with useful measurement techniques and data analysis algorithms.
Active beam position stabilization of pulsed lasers for long-distance ion profile diagnostics at the Spallation Neutron Source (SNS)
A high peak-power Q-switched laser has been used to monitor the ion beam profiles in the superconducting linac at the Spallation Neutron Source (SNS). The laser beam suffers from position drift due to movement, vibration, or thermal effects on the optical components in the 250-meter long laser beam transport line. We have designed, bench-tested, and implemented a beam position stabilization system by using an Ethernet CMOS camera, computer image processing and analysis, and a piezo-driven mirror platform. The system can respond at frequencies up to 30 Hz with a high position detection accuracy. With the beam stabilization system, we have achieved a laser beam pointing stability within a range of 2 rad (horizontal) to 4 rad (vertical), corresponding to beam drifts of only 0.5 mm 1 mm at the furthest measurement station located 250 meters away from the light source.
LASER BASED DIAGNOSTICS FOR MEASURING H- BEAM PARAMETERS
In recent years, a number of laser based H- beam diagnostics systems have been developed in the Spallation Neutron Source (SNS). This talk reviews three types of laser-based diagnostics at SNS: the laser wire profile monitors at superconducting linac (SCL), the laser based transverse emittance measurement system at high energy beam transport (HEBT), and the laser bunch shape monitor at medium energy beam transport (MEBT). Measurement performance will be reported and major technical challenges in the design, implementation, and operation of the laser based diagnostics at accelerator facilities will be addressed.