LLNL, Livermore, California, USA
LLNL's compact, tunable, laser-Compton x-ray source has been built around an advanced X-band photogun and accelerator sections and two independent laser systems. In support of this source, the control system has evolved from a minimal, isolated control points to an integrated architecture that continues to grow to simplify operation of the system and to meet new needs of this research capability. In addition to a PLC-based machine protection component, a custom, LabView-based suite of control software monitors systems including low level and high power RF, vacuum, magnets, and beam imaging cameras. This system includes a comprehensive operator interface, automated arc detection and rf processing to optimize rf conditioning of the high-gradient structures, and automated quad-scan-based emittance measurements to explore the beam tuning parameter space. The latest upgrade to the system includes a switch from real-time OS to FPGA-based low-level RF generation and arc detection. This offloads processing effort from the main processor allowing for arbitrary expansion of the monitored points. It also allows the possibility of responding to arcs before the pulse is complete.
UCI, Irvine, California, USA
LLNL, Livermore, California, USA
30 keV Compton-scattered X-rays have been produced at LLNL. The flux, bandwidth, and X-ray source focal spot size have been characterized using an X-ray ICCD camera and results agree very well with modeling predictions. The RMS source size inferred from direct electron beam spot size measurement is 17 um , while imaging of the penumbra yields an upper bound of 42 um. The accuracy of the latter method is limited by the spatial resolution of the imaging system, which has been characterized as well, and is expected to improve after the upgrade of the X-ray camera later this year.
LLNL, Livermore, California, USA
Lawrence Livermore National Lab is developing an intense, high-brightness fast neutron source to create high resolution neutron radiographs and images. An intense source (1011 n/s/sr at 0 degrees) of fast neutrons (10 MeV) allows: penetrating very thick, dense objects; maintaining high scintillator response efficiency; and remaining below the air activation threshold for (n,p) reactions. Fast neutrons will be produced using a pulsed 7 MeV, 300 microamp average-current commercial ion accelerator that will deliver deuterons to a 3 atmosphere deuterium gas cell. To achieve high resolution, a small (1.5 mm diameter) beam spot size will be used, and to reduce scattering from lower energy neutrons, a transmission gas cell will be used to produce a quasi-monoenergetic neutron beam. Because of the high power density of such a tightly focused, modest-energy ion beam, the gas target is a major engineering challenge that combines a 'windowless' rotating aperture, a rotary valve to meter cross-flowing high pressure gases, a novel gas beam stop, and recirculating gas compressor systems. A summary of the progress of the system design and building effort shall be presented.
