TY - CONF AU - Bergan, W.F. AU - Andorf, M.B. AU - Ehrlichman, M.P. AU - Khachatryan, V. AU - Rubin, D.L. AU - Wang, S. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Bypass Design for Testing Optical Stochastic Cooling at the Cornell Electron Storage Ring (CESR) J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - Optical Stochastic Cooling (OSC) is a promising method for cooling very dense stored particle beams through the interference of radiation created in an upstream ’pickup’ wiggler and a downstream ’kicker’ wiggler. By correlating a particle’s path length via a bypass between the two wigglers with its betatron coordinates in the pickup, the particle will receive a kick in energy which, through coupling introduced by non-zero horizontal dispersion in the kicker, can reduce its betatron amplitude, thus cooling the beam. A proof-of-principle test of this technique is being planned at the Cornell Electron Storage Ring (CESR). In addition to maintaining standard requirements such as a large dynamic aperture and acceptable lattice functions throughout the ring, the design of the bypass is guided by the mutually competing goals of maximizing the cooling rate while maintaining a sufficiently large cooling acceptance with properly-corrected nonlinearities. We present a design of such a bypass and ring optics so as to best achieve these objectives. PB - JACoW Publishing CP - Geneva, Switzerland SP - 360 EP - 363 KW - optics KW - sextupole KW - radiation KW - wiggler KW - damping DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-MOPGW100 UR - http://jacow.org/ipac2019/papers/mopgw100.pdf ER - TY - CONF AU - Lou, W. AU - Gulliford, C.M. AU - Hoffstaetter, G.H. AU - Mayes, C.E. AU - Sagan, D. AU - Tsoupas, N. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Coherent Synchrotron Radiation Simulation for CBETA J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - CBETA is an energy recovery linac accelerating from 6 MeV to 150 MeV in four linac passes, using a single return beamline accepting all energies from 42 to 150 MeV. While CBETA gives promise to deliver unprecedentedly high beam current with simultaneously small emittance, Coherent Synchrotron Radiation (CSR) can pose detrimental effect on the beam at high bunch charges and short bunch lengths. To investigate the CSR effects on CBETA, we used the established simulation code Bmad to track a bunch with different parameters. We found that CSR causes phase space dilution, and the effect becomes more significant as the bunch charge and recirculation pass increase. Potential ways to mitigate the effect involving vacuum chamber shielding and increasing bunch length are being investigated. PB - JACoW Publishing CP - Geneva, Switzerland SP - 406 EP - 409 KW - simulation KW - linac KW - lattice KW - radiation KW - shielding DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-MOPGW124 UR - http://jacow.org/ipac2019/papers/mopgw124.pdf ER - TY - CONF AU - Gulliford, C.M. AU - Banerjee, N. AU - Bartnik, A.C. AU - Berg, J.S. AU - Crittenden, J.A. AU - Quigley, P. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Using an Energy Scan to Determine the Tunes and Orbit in the First FFA Girder of CBETA J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - This work reports the results of performing a scan of the beam energy performed during the Fractional Arc Test of the CBETA machine, a multi-pass SRF ERL featuring a non-scaling FFA return loop. The FFA arc consists of identical doublets that are designed to have an energy acceptance from 42 to 150 MeV, with a betatron phase advance (i.e., tune) per cell and periodic orbit position that depends on energy. In the CBETA fractional arc test, we transport the beam through 4 such cells (the first girder), and are capable of injecting beam in to the arc with energies as high as 59 MeV. By creating betatron oscillations in the arc, we can compute the phase advance per cell and periodic orbit position as a function of energy within that range. In addition, because the phase advance varies as a function of energy, the computation also provides an estimate of the offsets of the BPMs in that arc. PB - JACoW Publishing CP - Geneva, Switzerland SP - 742 EP - 744 KW - betatron KW - linac KW - cryomodule KW - MMI KW - lattice DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-MOPRB074 UR - http://jacow.org/ipac2019/papers/moprb074.pdf ER - TY - CONF AU - Kostroun, V.O. AU - Gulliford, C.M. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Radiation Limits on Permanent Magnets in CBETA J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The Cornell Brookhaven Energy Recovery Linac Test Accelerator (CBETA), under construction at Cornell, uses Fixed Field Alternating Gradient (FFAG) Halbach magnets made from grade N35EH NdFeB. To reduce the 1% level magnetization errors in fabricated blocks to magnets with better than 0.001 field accuracy, iron wire shimming is necessary. This also limits magnetization changes by external influences to the ~1% level. The ambient radiation field present during CBETA operation can induce permanent magnet demagnetization. The radiation field arises from electrons in the beam halo hitting the vacuum chamber and from residual gas, Touschek and Intra-Beam scattering. The radiation dose rate due to electrons striking the vacuum chamber of a 4 cell straight section of CBETA FFAG magnets was calculated using the many particle Monte Carlo radiation code MCNP6.2. MCNP6.2 has a track-length heating tally for different particles and a collision heating tally that gives energy deposition/mass from all particles in the problem. Calculations show that electron loss has to be a fraction of a watt/m to keep the dose rate at an acceptable level during the accelerator lifetime. PB - JACoW Publishing CP - Geneva, Switzerland SP - 745 EP - 747 KW - radiation KW - electron KW - vacuum KW - permanent-magnet KW - focusing DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-MOPRB075 UR - http://jacow.org/ipac2019/papers/moprb075.pdf ER - TY - CONF AU - Gulliford, C.M. AU - Banerjee, N. AU - Bartnik, A.C. AU - Bazarov, I.V. AU - Berg, J.S. AU - Brooks, S.J. AU - Crittenden, J.A. AU - Deitrick, K.E. AU - Galdi, A. AU - Hoffstaetter, G.H. AU - Michnoff, R.J. AU - Quigley, P. AU - Smolenski, K.W. AU - Trbojevic, D. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - CBETA Beam Commissioning Results J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - We report on the first results of commissioning CBETAwith a fully closed return loop. We repeat much of our early commissioning from the fractional arc test, namely setting up the injection system, calibrating the main linac, and steering the beam through the first splitter line. Most importantly, first results from sending the beam all the way through the FixedField Alternating gradient permanent magnet return arc are described. PB - JACoW Publishing CP - Geneva, Switzerland SP - 748 EP - 750 KW - linac KW - MMI KW - permanent-magnet KW - electron KW - lattice DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-MOPRB076 UR - http://jacow.org/ipac2019/papers/moprb076.pdf ER - TY - CONF AU - Gulliford, C.M. AU - Banerjee, N. AU - Bartnik, A.C. AU - Berg, J.S. AU - Crittenden, J.A. AU - Quigley, P. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Results From the CBETA Fractional Arc Test J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - We report on commissioning experiments of the Cornell Brookhaven Energy Recovery Test Accelerator Fractional Arc Test. The beam from the injector is accelerated by a linac with a 36 MeV design energy gain, is transported through a splitter line that uses conventional magnets, and finally into a four cell permanent magnet based fixed field alternating (FFA) gradient arc. We measure beam properties in the injector, calibrate the energy gain and phase of the linac cavities using time of flight to a BPM at the end of the linac. We scan individual cavity phases and pass beam through the cavities to determine the transverse offset of the individual cavities. We scan the beam position in the splitter BPMs to estimate and correct the nonlinearity in the BPM response. We tested our path length adjustment mechanism. We measure the dispersion and R56 in the FFA arc. PB - JACoW Publishing CP - Geneva, Switzerland SP - 751 EP - 754 KW - linac KW - cavity KW - MMI KW - emittance KW - betatron DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-MOPRB077 UR - http://jacow.org/ipac2019/papers/moprb077.pdf ER - TY - CONF AU - Gulliford, C.M. AU - Bartnik, A.C. AU - Berg, J.S. AU - Crittenden, J.A. AU - Quigley, P. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Beam Based Measurements of the CBeta Main Linac Cavity Alignment J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - Initial attempts at steering the beam through the CBETA main linac indicated the cavities were vertically offset with respect to the BPMs on either side of the linac.  In particular, manual alignment of the beam in the first and last cavities suggested a vertical offset of roughly 5 mm.  This work presents the results of beam based measurements of the individual cavity offsets taken during the CBETA Fractional Arc Test.  With only a single cavity powered at a time, beam was injected at several different vertical offsets, the RF phase was scanned over 360 degrees, and the beam position was measured at the end of the cryomodule. We analyzed the data in two ways. We first compute the RMS spread in the measurements at a given position, and considered the offset with the minimum RMS spread to be the cavity offset. We also fit the measurements at a given phase to a line as a function of initial displacement, and use a model for the transfer matrix of the cavity and downstream drift to compute the offset. The two methods agree well, resulting in an average vertical offset of the main linac cavities of 4.0 plus/minus 1 mm. PB - JACoW Publishing CP - Geneva, Switzerland SP - 755 EP - 757 KW - cavity KW - linac KW - cryomodule KW - survey KW - acceleration DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-MOPRB078 UR - http://jacow.org/ipac2019/papers/moprb078.pdf ER - TY - CONF AU - Deitrick, K.E. AU - Crone, J. AU - Franck, C. AU - Hoffstaetter, G.H. AU - Kostroun, V.O. AU - Muratori, B.D. AU - Owen, H.L. AU - Smolenski, K.W. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - A Hard X-Ray Compact Compton Source at CBETA J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - Compton backscattering at energy recovery linacs (ERLs) promises high flux, high energy x-ray sources in the future, made possible by high quality, high repetition rate electron beams produced by ERLs. CBETA, the Cornell-BNL ERL Test Accelerator currently being built and commissioned at Cornell, is an SRF multi-turn ERL using Non-Scaling Fixed Field Alternating-gradient (NS-FFA) arcs. CBETA has high quality design parameters with an anticipated top energy of 150 MeV on the fourth pass. The expected parameters of a Compton source at CBETA include a top x-ray energy of over 400 keV with a flux on the order of 10¹² ph/s. In this paper, we present anticipated parameters and potential applications in science and engineering for this source. PB - JACoW Publishing CP - Geneva, Switzerland SP - 1604 EP - 1605 KW - electron KW - laser KW - photon KW - scattering KW - brilliance DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-TUPGW085 UR - http://jacow.org/ipac2019/papers/tupgw085.pdf ER - TY - CONF AU - Koscica, R.M. AU - Banerjee, N. AU - Gulliford, C.M. AU - Hoffstaetter, G.H. AU - Lou, W. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Energy and RF Cavity Phase Symmetry Enforcement in Multi-Turn ERL Models J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - In a multi-pass Energy Recovery Linac (ERL), each cavity must regain all energy expended from beam acceleration during beam deceleration, and the beam should achieve specific energy targets during each loop that returns it to the linac. For full energy recovery, and for every returning beam to meet loop energy requirements, we must optimize the phase and voltage of cavity fields in addition to selecting adequate flight times. If we impose symmetry in time and energy during acceleration and deceleration, fewer parameters are needed, simplifying the optimization. As an example, we present symmetric models of the Cornell BNL ERL Test Accelerator (CBETA) with solutions that satisfy the optimization targets of loop energy and zero cavity loading. PB - JACoW Publishing CP - Geneva, Switzerland SP - 1606 EP - 1608 KW - cavity KW - linac KW - acceleration KW - target KW - electron DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-TUPGW086 UR - http://jacow.org/ipac2019/papers/tupgw086.pdf ER - TY - CONF AU - Michnoff, R.J. AU - Banerjee, N. AU - Barley, J. AU - Bartnik, A.C. AU - Bazarov, I.V. AU - Berg, J.S. AU - Brooks, S.J. AU - Burke, D.C. AU - Cintorino, J. AU - Crittenden, J.A. AU - Cultrera, L. AU - Dobbins, J. AU - Douglas, D. AU - Dunham, M. AU - Full, S.J. AU - Furuta, F. AU - Gallagher, R.E. AU - Ge, M. AU - Gulliford, C.M. AU - Hao, Y. AU - Heltsley, B.K. AU - Hoffstaetter, G.H. AU - Jusic, D. AU - Kaplan, R.P.K. AU - Kostroun, V.O. AU - Li, Y. AU - Liepe, M. AU - Liu, C. AU - Lou, W. AU - Mahler, G.J. AU - Mayes, C.E. AU - Méot, F. AU - Patterson, J.R. AU - Peggs, S. AU - Ptitsyn, V. AU - Quigley, P. AU - Roser, T. AU - Sabol, D.M. AU - Sagan, D. AU - Sears, J. AU - Shore, C.H. AU - Smith, E.N. AU - Smolenski, K.W. AU - Thieberger, P. AU - Trabocchi, S. AU - Trbojevic, D. AU - Tsoupas, N. AU - Tuozzolo, J.E. AU - Veshcherevich, V. AU - Widger, D. AU - Willeke, F.J. AU - Witte, H. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - CBETA - Novel Superconducting ERL J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - We are successfully commissioning a unique Cornell University and Brookhaven National Laboratory Electron Recovery Linac (ERL) Test Accelerator ’CBETA’ [1]. The ERL has four accelerating passes through the supercon-ducting linac with a single Fixed Field Alternating Linear Gradient (FFA-LG) return beam line built of the Halbach type permanent magnets. CBETA ERL accelerates elec-trons from 42 MeV to 150 MeV, with the 6 MeV injec-tor. The novelties are that four electron beams, with ener-gies of 42, 78, 114, and 150 MeV, are merged by spreader beam lines into a single arc FFA-LG beam line. The elec-tron beams from the Main Linac Cryomodule (MLC) pass through the FFA-LG arc and are adiabatically merged into a single straight line. From the straight section the beams are brought back to the MLC the same way. This is the first 4 pass superconducting ERL and the first single permanent magnet return line. PB - JACoW Publishing CP - Geneva, Switzerland SP - 1651 EP - 1653 KW - electron KW - linac KW - MMI KW - operation KW - cryomodule DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-TUPGW102 UR - http://jacow.org/ipac2019/papers/tupgw102.pdf ER - TY - CONF AU - Stefani, M.S. AU - Gulliford, C.M. AU - Hannon, F.E. AU - Kostroun, V.O. AU - Mayes, C.E. AU - Poelker, M. AU - Smolenski, K.W. AU - Suleiman, R. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Magnetized Gridded Thermionic Electron Source J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The study of magnetized electron beam has become a high priority for its use in ion beam cooling as part of Electron Ion Colliders and the potential of easily forming flat beams for various applications. The demand for high average current for effective ion beam cooling has caused consideration of using bunched magnetized electron beam produced by a gridded thermionic electron gun. This paper presents the design of a potential electron source for JCIEC first measurements characterizing the beam properties of a magnetized thermionic gun. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2140 EP - 2143 KW - electron KW - gun KW - cathode KW - emittance KW - simulation DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-TUPTS093 UR - http://jacow.org/ipac2019/papers/tupts093.pdf ER - TY - CONF AU - Michnoff, R.J. AU - Dobbins, J. AU - Hulsart, R.L. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - The CBETA Beam Position Monitor (BPM) System Design and Strategy for Measuring Multiple Simultaneous Beams in the Common Beam Pipe J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - CBETA, a 4-pass electron Energy Recovery Linac (ERL) is presently under construction at Cornell University and is a collaboration between Brookhaven National Laboratory (BNL) and Cornell University. Beam commissioning began in March 2019 with a single pass ERL configuration. Commissioning of the complete 4-pass machine is scheduled to begin in fall 2019. The fixed field alternating gradient (FFA) return loop for CBETA uses Halbach permanent magnets with a common beam pipe for seven different energy beams (4 accelerating energies and 3 decelerating energies). One of the most challenging requirements for the CBETA BPM system is to independently measure the position of each of these beams. The overall design of the CBETA BPM system and the techniques planned to measure the position of each energy beam will be presented. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2736 EP - 2738 KW - timing KW - injection KW - hardware KW - electron KW - MMI DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPGW104 UR - http://jacow.org/ipac2019/papers/wepgw104.pdf ER - TY - CONF AU - Banerjee, N. AU - Deitrick, K.E. AU - Dobbins, J. AU - Hoffstaetter, G.H. AU - Kaplan, R.P.K. AU - Liepe, M. AU - Miller, C.W. AU - Quigley, P. AU - Smith, E.N. AU - Veshcherevich, V. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - RF Commissioning and Performance in the CBETA ERL J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The Cornell-BNL ERL Test Accelerator (CBETA) is a new multi-turn energy recovery linac currently being commissioned at Cornell University. It uses a superconducting main linac to accelerate electrons by 36 MeV and recover their energy. The energy recovery process is sensitive to fluctuations in the accelerating field of all cavities. In this paper, we outline our semi-automated RF commissioning procedure, which starts from automatic coarse tuning of the cavity all the way to adjusting the field control loops. We show some results of using these tools and describe the recent performance of the RF system during our ongoing commissioning phase. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3003 EP - 3006 KW - cavity KW - operation KW - controls KW - linac KW - LLRF DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPRB078 UR - http://jacow.org/ipac2019/papers/weprb078.pdf ER - TY - CONF AU - Ge, M. AU - Gruber, T. AU - Kaufman, J.J. AU - Koufalis, P.N. AU - Kulina, G. AU - Liepe, M. AU - Maniscalco, J.T. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - High-gradient SRF Cavity R&D at Cornell University J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - Achieving high accelerating field is a critical R&D topic for superconducting RF cavities for future accelerators including the International Linear collider (ILC). The ILC requires an average accelerating field of 35MV/m with a Q₀ of at least 8.9·10⁹ at 2K. In this paper, we report the latest results from high-gradient research at Cornell, which focusses on 75C vacuum baking to improve maximum (quench) fields. We demonstrate that such low temperature bakes can significantly improve quench fields in certain cases by mitigating localized defects. We further report on high-pulsed power results of these cavities before and after baking. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3017 EP - 3019 KW - cavity KW - SRF KW - collider KW - linear-collider KW - vacuum DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPRB087 UR - http://jacow.org/ipac2019/papers/weprb087.pdf ER - TY - CONF AU - Maniscalco, J.T. AU - Arias, T. AU - Liarte, D. AU - Liepe, M. AU - Sethna, J.P. AU - Sitaraman, N. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Theoretical Analysis of Quasiparticle Overheating, Positive Q-Slope, and Vortex Losses in SRF Cavities J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The surface resistance of an SRF cavity is an important measure of its performance and utility: lower resistance leads directly to lower cryogenic losses and power consumption. This surface resistance comprises two components, namely the ‘‘BCS resistance’’, which depends strongly on the quasiparticle temperature, and a temperature-independent ‘‘residual resistance’’, which is often dominated by losses due to trapped magnetic vortices. Both components are generally dependent on the RF field strength. Here we present a summary of recent theoretical advances in understanding the microscopic mechanisms of the surface resistance, in particular addressing niobium hydride formation and quasiparticle overheating (using the tools of density functional theory) and discussing issues with existing models of the positive Q-slope, a field-dependent decrease in the BCS resistance, and possible paths for improvement of these models. We also discuss trapped flux losses using ideas from collective weak pinning theory. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3020 EP - 3023 KW - cavity KW - SRF KW - niobium KW - electron KW - experiment DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPRB089 UR - http://jacow.org/ipac2019/papers/weprb089.pdf ER - TY - CONF AU - Gordon, M.A. AU - Kim, Y.K. AU - Maxson, J.M. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - The Effects of Stochastic Space Charge in High Brightness Photolectron Beamlines for Ultrafast Electron Diffraction J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - As we move to ultra-high brightness photocathodes and ultra-cold beams, we may become more sensitive to stochastic, point-to point effects such as disorder induced heating and the Boersch effect, given the failure of Debye screening.  In this study, we explore the effects of stochastic scattering. Modern beam dynamics codes often approximate point to point interactions with a potential created by smoothing the charge over space, removing sensitivity to stochastic effects. This approximation is often used in beamline optimization, because it is much faster. We study the limits of validity of this approximation. In particular, we will simulate effects of stochastic space charge on a high brightness photoemission beamline, an ultrafast electron diffraction beamline with a photocathode temperature of 5 meV with a final beam energy of 225 keV. Emittance dilution in the transverse plane and transverse beam size relative to smooth space charge simulations will be presented. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3283 EP - 3285 KW - space-charge KW - simulation KW - electron KW - emittance KW - cathode DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPTS069 UR - http://jacow.org/ipac2019/papers/wepts069.pdf ER - TY - CONF AU - Bergan, W.F. AU - Khachatryan, V. AU - Rubin, D.L. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Helical Wiggler Model for Fast Tracking J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - In order to test the process of Optical Stochastic Cooling (OSC) at the Cornell Electron Storage Ring (CESR), we plan to use helical wigglers as both the pickup and kicker, since the required radiation wavelength of 800nm can be achieved with lower magnetic field strength in helical as compared to planar wigglers. In order to simulate the lattice with such wigglers, it is useful to be able to model the effect of the wiggler on the optics without resorting to direct tracking, which is time-consuming and so ill-suited for the repeated evaluations necessary in running an optimizer. We generate a Taylor map to third order for this element using analytic field expressions, enabling easy determination of the effects of such an element on linear and nonlinear optics. This model is compared with the results of direct tracking and shows good agreement. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3356 EP - 3359 KW - wiggler KW - radiation KW - electron KW - optics KW - undulator DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPTS102 UR - http://jacow.org/ipac2019/papers/wepts102.pdf ER - TY - CONF AU - Bergan, W.F. AU - Bazarov, I.V. AU - Duncan, C.J.R. AU - Rubin, D.L. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Applications of Dimension-Reduction to Various Accelerator Physics Problems J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - Particle accelerators contain hundreds of magnets, making dimension-reduction techniques attractive when attempting to tune them. We apply this procedure to two different problems: correcting the orbit in the Cornell synchrotron and maximizing the dynamic aperture in the Cornell Electron Storage Ring (CESR). Cornell’s rapid cycling synchrotron accepts a 200 MeV beam from the linac and accelerates it to 6 GeV for injection into the CESR. ‘Kicker coils’ (dipole correctors) are used to correct for residual fields which would otherwise cause beam loss at the low energies. In such cases, it is usually advisable to measure and correct the orbit. However, one cannot measure the orbit without first getting the beam to circulate a few hundred times, by which point the low-energy orbit would already be mostly corrected. In order to speed up the process of empirical orbit tuning, we form knobs which have the largest effect on the global orbit error, so that the dimensionality of the space which must be searched may be greatly reduced. A small dynamic aperture in CESR will have adverse effects on beam lifetime and injection efficiency, and so ought to be maximized by tuning sextupoles. However, it is often unclear which sextupoles one ought to tune to alleviate the problem. Moreover, once the chromaticity is properly adjusted, it should not be changed. Since we expect resonance driving terms (RDTs) to have a large impact on the dynamic aperture, we develop sextupole knobs which change the RDTs as much as possible while leaving the chromaticity fixed. PB - JACoW Publishing CP - Geneva, Switzerland SP - 4060 EP - 4062 KW - dynamic-aperture KW - kicker KW - sextupole KW - synchrotron KW - storage-ring DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-THPRB099 UR - http://jacow.org/ipac2019/papers/thprb099.pdf ER - TY - CONF AU - Duncan, C.J.R. AU - Andorf, M.B. AU - Bazarov, I.V. AU - Gulliford, C.M. AU - Khachatryan, V. AU - Maxson, J.M. AU - Rubin, D.L. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - A Generic Software Platform for Rapid Prototyping of Online Control Algorithms J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - Algorithmic control of accelerators is an active area of research that promises significant improvements in machine performance. To facilitate rapid algorithm prototyping, we have developed a generic interface between accelerator controls, beam physics modelling software and modern scripting languages. The work-flow of a project using this interface begins with testing algorithms of choice offline in simulation. After off-line testing, the same code can be deployed on real machines via the Experimental Physics and Industrial Control System (EPICS) API. We include noise in our simulations in order to mimic realistic accelerator behaviour and to evaluate robustness of algorithms to experimental uncertainties and long-term drifts. The results of test cases of using this framework are presented, including emittance tuning of the Cornell Electron Storage Ring (CESR), correction of diurnal drift in CESR steering and orbit correction on CESR and the Cornell-BNL ERL Test Accelerator (CBETA). PB - JACoW Publishing CP - Geneva, Switzerland SP - 4063 EP - 4065 KW - simulation KW - controls KW - software KW - interface KW - EPICS DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-THPRB100 UR - http://jacow.org/ipac2019/papers/thprb100.pdf ER -