Search NASA⌕ Search

Engineering topics

Wu, S S

Publications and source records attributed to Wu, S S.

Precision linac and laser technologies for nuclear photonics gamma-ray sources

Tunable, high precision gamma-ray sources are under development to enable nuclear photonics, an emerging field of research. This paper focuses on the technological and theoretical challenges related to precision Compton scattering gamma-ray sources. In this scheme, incident laser photons are scattered and Doppler upshifted by a high brightness electron beam to generate tunable and highly collimated gamma-ray pulses. The electron and laser beam parameters can be optimized to achieve the spectral brightness and narrow bandwidth required by nuclear photonics applications. A description of the design of the next generation precision gamma-ray source currently under construction at Lawrence Livermore National Laboratory is presented, along with the underlying motivations. Within this context, high-gradient X-band technology, used in conjunction with fiber-based photocathode drive laser and diode pumped solid-state interaction laser technologies, will be shown to offer optimal performance for high gamma-ray spectral flux, narrow bandwidth applications.

43 PARTICLE ACCELERATORS↗

Ultracompact Accelerator Technology for a Next-Generation Gamma-Ray Source

This presentation reported on the technology choices and progress manufacturing and testing the injector and accelerator of the 250 MeV ultra-compact Compton Scattering gamma-ray Source under development at LLNL for homeland security applications. This paper summarizes the status of various facets of current accelerator activities at LLNL. The major components for the X-band test station have been designed, fabricated, and await installation. The XL-4 klystron has been delivered, and will shortly be dressed and installed in the ScandiNova modulator. High power testing of the klystron into RF loads will follow, including adjustment of the modulator for the klystron load as necessary. Assembly of RF transport, test station supports, and accelerator components will follow. Commissioning will focus on processing the RF gun to full operating power, which corresponds to 200 MV/m peak electric field on the cathode surface. Single bunch benchmarking of the Mark 1 design will provide confidence that this first structure operates as designed, and will serve as a solid starting point for subsequent changes, such as a removable photocathode, and the use of various cathode materials for enhanced quantum efficiency. Charge scaling experiments will follow, partly to confirm predictions, as well as to identify important causes of emittance growth, and their scaling with charge. Multi-bunch operation will conclude testing of the Mark 1 RF gun, and allow verification of code predictions, direct measurement of bunch-to-bunch effects, and initial implementation compensation mechanisms. Modeling will continue and focus on supporting the commissioning and experimental program, as well as seeking to improve all facets of linac produced Compton gamma-rays.

42 ENGINEERING↗

Compton Scattering Sources and Applications at LLNL

We report the design and current status of a monoenergetic laser-based Compton scattering 0.5-2.5 MeV {gamma}-ray source. Previous nuclear resonance fluorescence results and future linac and laser developments for the source are presented.

43 PARTICLE ACCELERATORS↗