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The U.S. Spallation Neutron Source (SNS) is a state-of-the-art neutron scattering facility delivering the world’s most intense pulsed neutron beams to a wide array of instruments, which are used to conduct investigations in many fields of engineering, physics, chemistry, material science, and biology. Neutrons are produced by spallation of liquid Hg by the bombardment of short (∼1 µs), intense (∼35 A) pulses of protons delivered at 60 Hz by an accumulator ring which is fed by a high-intensity, 1 GeV, H− LINAC (linear accelerator). This facility has operated nearly continuously since 2006 but has recently undergone a 4-month maintenance period, which featured a complete replacement of the 2.5 MeV injector feeding the LINAC. The new injector was developed at ORNL in an off-line beam test facility and consists of an ion source, low energy beam transport, and a Radio Frequency Quadrupole (RFQ). This report first describes the installed configuration of the new injector detailing the ion source system. The first beam current, RFQ transmission, emittance, and energy measurements from the injector installed on the SNS are reported. These data not only show a significant performance improvement for our existing facility but will also make accessible the higher beam current requirements for future SNS upgrade projects: the proton power upgrade and second target station.

Described is a system that will provide isolated electric power for a circuit that drives the core reset of a pulsed power modulator. This can be accomplished by coupling light from a number of diode laser bars to bundles of 200 urn multimode optical fibers. This is then coupled to photo-voltaic power converters that will deliver 16 V 29 mA of electricity from 1 watt of optical power. Spot size at the bundle face is a Gausian ellipse with a major axis of 1.4 mm radius and a minor axis of 0.118 mm with a maximum full angle divergence of 16 X 2.4 degrees. Data is presented from four 20 W laser bars coupled to four bundles of 12 fibers generating a total of 24 W of electrical power. Various schemes are used to maximize coupling into the optical fiber while limiting the number of optical components, and comparing components such as fresnel and aspheric lenses and lens ducts for effectiveness and cost. This will provide a completely isolated low power source for high voltage, high current environments where traditional isolation techniques yield inadequate isolation or prove too cumbersome.

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