Engineering topics

Musson, John C.

Publications and source records attributed to Musson, John C..

4 records

DOE OSTI2024

High power pulse systems for surface processing

A high-power pulsed surface processing system includes insulated-gate bipolar transistors (IGBT) to replicate desirable pulse structures with high precision, at low cost, and with high reliability within a single system. The pulsed surface processing system includes a power supply, an anode and a cathode, a dual gate driver supplying power to one or more IGBT gates, and one or more capacitor banks. Pulse formation software controls the timing and duration of electrical pulses to the electrodes. A freewheeling diode protects the system from an abrupt reduction of current in the circuit. The high-power pulsed surface processing system may be used to control versatile and complex pulse structures while with precise control of instantaneous pulse powers, pulse timing, and process control. The inclusion of dual gate drivers also offers the ability for multiple pulsers to be created and “slaved” together for a wide variety of custom processes.

Tian, Hui↗

DOE OSTI2018

Commissioning of JLab Vertical Cavity Processing System for SRF Nb Single Cell and Multicell Cavity With HF-Free Pulse-Reverse Electopolishing

Pulse reversed electropolishing of niobium SRF cavities, using a dilute aqueous H2SO4 electrolyte without HF yields equivalent RF performance with traditional EP. Comparing with present EP process for Nb SRF cavity which uses 1:10 volume ratio of HF (49%) and H2SO4 (98%), pulse reverse EP (also known as bipolar EP (BPEP)) is ecologically friendly and uses relatively benign electrolyte options for cavity processing. In this study, we report the commissioning of a new vertical cavity processing system for SRF Nb single cell and multi-cell cavities with HF-free pulse-reverse electropolishing at Jefferson Lab, together with RF test of cavities being processed. We report the scale-up challenges and interpretations from process R&D to implementation.

Tian, Hui↗

DOE OSTI2016

Development of an Ultra Fast RF Kicker for an ERL-based Electron Cooler

The staged approach to electron cooling proposed for Jefferson Lab's Medium Energy Electron-Ion Collider (MEIC) utilizes bunched beam electron cooling with a single-pass energy recovery linac (ERL) for cooling in the ion collider ring. Possible luminosity upgrades make use of an ERL and full circulator ring and will require ultra-fast kickers that are beyond current technology. A novel approach to generating the necessary ultra fast (ns-level) RF kicking pulse involves the summation of specific subharmonics of the cooling electron bunch frequency; the resultant kicking pulse is then naturally constrained to have rise and fall times equal to the electron bunch frequency. The uniformity of such a pulse and its effects on the beam dynamics of the cooling electron bunch are discussed.

Sy, Amy V.↗

DOE OSTI2012

APPLICATION OF NEURAL NETWORK ALGORITHMS FOR BPM LINEARIZATION

Stripline BPM sensors contain inherent non-linearities, as a result of field distortions from the pickup elements. Many methods have been devised to facilitate corrections, often employing polynomial fitting. The cost of computation makes real-time correction difficult, particulalry when integer math is utilized. The application of neural-network technology, particularly the multi-layer perceptron algorithm, is proposed as an efficient alternative for electrode linearization. A process of supervised learning is initially used to determine the weighting coefficients, which are subsequently applied to the incoming electrode data. A non-linear layer, known as an activation layer, is responsible for the removal of saturation effects. Implementation of a perceptron in an FPGA-based software-defined radio (SDR) is presented, along with performance comparisons. In addition, efficient calculation of the sigmoidal activation function via the CORDIC algorithm is presented.

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