Abstract: A high current bi-polar pulse system for use in electrochemical metal surface finishing of metallic components. The high current bi-polar pulse system provides a high isolation, high current switching device for providing independently controllable, alternating polarity, variable time duration pulses for electrochemical and mechanical finishing of metallic components in a conducting fluid bath. The high current bi-polar pulse system provides a safe, low-cost solution for implementing the surface finishing of niobium (Nb) SRF accelerating cavities without the use of hydrofluoric acid.

Abstract: A process that provides the ability to incorporate a self exciting loop (SEL) algorithm into a digital LLRF system. The present digital SEL provides for conversion from the Cartesian domain to the Polar domain, wherein most signal processing is accomplished, and back to Cartesian. By handling most signal processing in the Polar (phase & amplitude) domain, a perfect amplitude limiter can be realized and simpler logic operations can be used. When operational, cavity recovery from faults will be tuner-less. At high gradients, ˜20 MV/m, like those needed for the upgraded cryomodules, the Lorentz detuning will be many bandwidths, making cavity turn-on problematic with out some tuner based compensation or other algorithmic solution. The present SEL solves this problem and allows cavity recovery from cryogenic trips, wherein cavities have been known to detune 1000's of Hz. Other applications such has He processing can also be implemented in situ without additional electronics.