| Paper | Title | Page |
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| MOPLO09 | A Pulsed, Current Regulated Magnet Power Supply for Small Magnets | 252 |
| SUPLS03 | use link to see paper's listing under its alternate paper code | |
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Funding: Work supported by U. S. Department of Energy grant number DESC00010301 The University of Maryland Electron Ring (UMER) has two pulsed quadrupoles in the injection section that must be current regulated to the same precision as the other DC quadrupoles in the ring, as well as accurately synchro-nized to the ring operating cycle. To meet this need, a practical pulsed current, regulated power supply has been designed and built using a commercial power operational amplifier for output, standard operational amplifiers for feedback control and monitoring, and matched resistor pairs to produce the desired transfer function of 10 Volts to 6 Amperes. For other applications the circuit can be modified to produce a range of transfer functions by varying the appropriate resistor pair ratios. Output pulse width and timing are generated by a standardized TTL pulse from the control system that gates the output of the amplifier. Installed safety circuitry detects the absence of a proper control pulse, an open circuit or shorted output, and measures and returns to the control system the actual operating amplitude of the current pulse. In this paper we present the design, implementation, and operational results of the prototyped pulsed current source. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO09 | |
| About • | paper received ※ 28 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019 | |
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| TUPLM01 | Experimental Studies of Resonance Structure Dynamics With Space Charge | 372 |
| SUPLM04 | use link to see paper's listing under its alternate paper code | |
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Funding: Funding for this project is provided by DOE-HEP award #DE-SC0010301 Space charge is one of the fundamental limitations for next generation high intensity circular accelerators. It can lead to halo growth as well as beam loss, and affect resonance structure in ways not completely understood. We employ the University of Maryland Electron Ring (UMER), a circular 10 keV storage machine, to experimentally study the structure of betatron resonances for beams of varying degrees of space charge intensity. Experimental techniques such as tune scans and frequency maps are employed. Results are also compared to computer simulations using the WARP code. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM01 | |
| About • | paper received ※ 26 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019 | |
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| TUPLM03 | Adjoint Approach to Accelerator Lattice Design | 376 |
| TUPLM02 | use link to see paper's listing under its alternate paper code | |
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Funding: Supported by USDoE DESC0010301 Accelerator lattices are designed using computer codes that solve the equations of motion for charged particles in both prescribed and self-consistent fields. These codes are run in a mode in which particles enter a lattice region, travel for a finite distance, and have their coordinates recorded to assess various figures of merit (FoMs). The lattice is then optimized by varying the positions and strengths of the focusing elements. This optimization is done in a high dimensional parameter space, requiring multiple simulations of the particle trajectories to determine the dependence of the confinement on the many parameters. Sophisticated algorithms for this optimization are being introduced. However, the process is still time consuming. We propose to alter the design process using "adjoint" techniques [*]. Incorporation of an "adjoint" calculation of the trajectories and self-fields can, in several runs, determine the gradient in parameter space of a given FoM with respect to all lattice parameters. It includes naturally self-fields and can be embedded in existing codes such as WARP or Vorpal. The theoretical basis for the method and several applications will be presented. * T. Antonsen, D. Chernin, J. Petillo, Adjoint Approach to Beam Optics Sensitivity Based on Hamiltonian Particle Dynamics, 2018 arXiv:1807.07898, Physics of Plasmas 26, 013109 (2019). |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM03 | |
| About • | paper received ※ 23 August 2019 paper accepted ※ 13 September 2019 issue date ※ 08 October 2019 | |
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| TUPLM22 | Off Axis Dependence of Current Dependent Coherent Tune Shifts in the UMER Ring | 422 |
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Funding: Work supported by U. S. Department of Energy grant number DESC00010301 The University of Maryland Electron Ring (UMER) was built to explore space charge effects in the extreme - beyond the space charge limit of most existing storage rings. At the nominal operating kinetic energy of 10 keV, the beam is also non relativistic. We have experimentally verified that the current dependent coherent tune shift obeys the Laslett formula over a wide current range for a cylindrical geometry and non penetrating magnetic fields when the beam is on axis; i.e. the average closed orbit displacement around the ring is essentially zero.* In the current experiment this measurement is extended to the change in current dependent coherent tune shift as the average closed orbit is moved off axis. It can be displaced over approximately ±10 mm of the vacuum pipe diameter of 50 mm without loss of beam. Because the 36 bending magnets in UMER are very short, we treat each of them as a local kick and then increment each by a calculated small amount to achieve the desired, global closed orbit displacement. Experimental results are compared to predictions by Zotter and others. * D. für Sutter, M.Cornacchia, et al, "Current dependent tune shifts in the University of Maryland electron ring", NAPAC 2013. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM22 | |
| About • | paper received ※ 29 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019 | |
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