NAPAC2019 - List of Keywords (solenoid)

Paper	Title	Other Keywords	Page
MOZBB5	Magnetized Electron Source for JLEIC Cooler	cathode, electron, gun, high-voltage	83
	R. Suleiman, P.A. Adderley, J.F. Benesch, D.B. Bullard, J.M. Grames, J. Guo, F.E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, G.A. Krafft, M.A. Mamun, M. Poelker, M.G. Tiefenback, Y.W. Wang, S. Zhang JLab, Newport News, Virginia, USA J.R. Delayen, G.A. Krafft, S.A.K. Wijethunga, J.T. Yoskowitz ODU, Norfolk, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and supported by Laboratory Directed Research and Development funding. Magnetized bunched-beam electron cooling is a critical part of the Jefferson Lab Electron Ion Collider (JLEIC). Strong cooling of ion beams will be accomplished inside a cooling solenoid where the ions co-propagate with an electron beam generated from a source immersed in magnetic field. This contribution describes the production and characterization of magnetized electron beam using a compact 300 kV DC high voltage photogun and bialkali-antimonide photocathodes. Beam magnetization was studied using a diagnostic beamline that includes viewer screens for measuring the shearing angle of the electron beamlet passing through a narrow upstream slit. Correlated beam emittance with magnetic field at the photocathode was measured for various laser spot sizes. Measurements of photocathode lifetime were carried out at different magnetized electron beam currents up to 28 mA and high bunch charge up to 0.7 nano-Coulomb was demonstrated.
	Slides MOZBB5 [9.236 MB]
	Poster MOZBB5 [1.564 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOZBB5
About •	paper received ※ 27 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019
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MOPLH04	Design for HyRES Cathode Nanotip Electron Source	electron, cavity, gun, cathode	177
	R.M. Hessami, A.F. Amhaz, P. Musumeci UCLA, Los Angeles, USA
	A new ultrafast electron diffraction (UED) instrument is being developed by UCLA-Colorado University collaboration for the STROBE NSF Center with the goal of using electron and EUV photon beams to reveal the structural dynamics of materials in non-equilibrium states at fundamental atomic and temporal scales. This paper describes the design of the electron beamline of this instrument. In order to minimize the initial emittance, a nanotip photocathode, 25 nm in radius, will be used. This requires a redesign of the cathode and anode components of the electron gun to allow for the tip to be properly aligned. Solenoidal lenses are used to focus the beam transversely to a sub-micron spot at the sample and a radiofrequency (RF) cavity, driven by a continuous wave S-band RF source, longitudinally compresses the beam to below 100 fs, required for atomic resolution.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLH04
About •	paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUYBA3	Benchmarking the LCLS-II Photoinjector	simulation, laser, gun, emittance	301
	N.R. Neveu, T.J. Maxwell, C.E. Mayes SLAC, Menlo Park, California, USA
	Funding: DOE Contract No. DE-AC02-76SF00515 Commissioning of the LCLS-II photoinjector started in late 2018. Efforts to accurately model the gun and laser profiles is ongoing. Simulations of the photoinjector and solenoid are performed in ASTRA, IMPACT-T and OPAL-T. This work includes efforts to use the laser profile at the virtual cathode as the initial transverse beam distribution, and effects of 2D and 3D field maps. Beam size results are compared to experimental measurements taken at the YAG screen located after the gun.
	Slides TUYBA3 [1.320 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUYBA3
About •	paper received ※ 29 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUZBA4	Interaction Region Magnets for Future Electron-Ion Collider at Jefferson Lab	quadrupole, electron, interaction-region, collider	345
	R. Rajput-Ghoshal, C. Hutton, F. Lin, T.J. Michalski, V.S. Morozov, M. Wiseman JLab, Newport News, Virginia, USA
	The Jefferson Lab Electron Ion Collider (JLEIC) is a proposed new machine for nuclear physics research. It uses the existing CEBAF accelerator as a full energy injector to deliver 3 to 12 GeV electrons into a new electron collider ring. An all new ion accelerator and collider complex will deliver up to 200 GeV protons. The machine has luminosity goals of 10³⁴ cm^-2 ses⁻¹. The whole detector region including forward detection covers about 80 meters of the JLEIC complex. The interaction region design has recently been optimized to accommodate 200 GeV proton energy using conventional NbTi superconducting magnet technology. This paper will describe the requirements and preliminary designs for both the ion and electron beam magnets in the most complex 32 m long interaction region (IR) around the interaction point (IP). The interaction region has over thirty-seven superconducting magnets operating at 4.5K; these include dipoles, quadrupoles, skew-quadrupoles, solenoids, horizontal and vertical correctors and higher order multipole magnets. The paper will also discuss the electromagnetic interaction between these magnets.
	Slides TUZBA4 [6.444 MB]
	Poster TUZBA4 [1.549 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUZBA4
About •	paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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TUPLM07	First Experimental Observations of the Plasma-Cascade Instability in the CeC PoP Accelerator	electron, plasma, experiment, lattice	379
	I. Petrushina SUNY SB, Stony Brook, New York, USA Y.C. Jing, V. Litvinenko, J. Ma, I. Pinayev, G. Wang, Y.H. Wu BNL, Upton, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA K. Shih SBU, Stony Brook, New York, USA
	Preservation of the beam quality is important for attaining the desirable properties of the beam. Collective effects can produce an instability severely degrading beam emittance, momentum spread and creating filamentation of the beam. Microbunching instability for beams traveling along a curved trajectory, and space charge driven parametric transverse instabilities are well-known and in-depth studied. However, none of the above include a microbunching longitudinal instability driven by modulations of the transverse beam size. This phenomenon was observed for the first time during the commissioning of the CeC PoP experiment. Based on the dynamics of this instability we named it a Plasma-Cascade Instability (PCI). PCI can strongly intensify longitudinal micro-bunching originating from the beam’s shot noise, and even saturate it. Resulting random density and energy microstructures in the beam can become a serious problem for generating high quality electron beams. On the other hand, such instability can drive novel high-power sources of broadband radiation. In this paper we present our experimental observations of the PCI and the supporting results of the numerical simulations.
	Poster TUPLM07 [17.319 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM07
About •	paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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TUPLH03	Double-Bend Achromat Beamline for Injection Into a High-Power Superconducting Electron Linac	electron, gun, dipole, cavity	494
	C.H. Boulware, T.L. Grimm, R. Hipple Niowave, Inc., Lansing, Michigan, USA S.M. Lund FRIB, East Lansing, Michigan, USA V.S. Morozov JLab, Newport News, Virginia, USA
	To take advantage of the high duty cycle operation of superconducting electron linacs, commercial systems use thermionic cathode electron guns that fill every RF bucket with an electron bunch. In continuous operation, the exit energy is limited when compared to pulsed systems. Bunch length and energy spread at the exit of the gun are incompatible with low losses in the superconducting cavity. A solenoid double-bend achromatic beamline is in operation at Niowave which allows energy and bunch length filtering of the beam leaving the gun before injection into the superconducting cavity. This system uses two solenoids and two dipoles to produce a round beam, using the edge angles of the dipoles to balance the focusing effects in the two transverse planes. The design allows beam filtering on the symmetry plane where the dispersion is maximum. Additionally, the bend angle moves the electron gun off the high-energy beam axis, allowing multiple-pass operation of the superconducting booster. This contribution will discuss the beam optics design of the double-bend achromat along with the design of the magnets and beam chambers and the operational experience with the system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH03
About •	paper received ※ 28 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019
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TUPLO02	Spin Dynamics in the JLEIC Ion Injector Linac	linac, proton, rfq, focusing	533
	J.L. Martinez Marin, B. Mustapha ANL, Lemont, Illinois, USA L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: This work was supported by the U.S. DOE, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 for ANL and by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. One of the requirements for the future Electron Ion Col-lider (EIC) is to collide polarized electrons and light ions with at least 70% polarization for each beam. For light ions, polarized ion sources are used for injection to a linac, which is usually the first accelerator in the collider chain. The Jefferson Lab EIC (JLEIC) ion injector linac consists of a low-energy room-temperature section with quadrupole focusing followed by a superconducting linac with solenoid focusing inside long cryomodules. These two sections have different effects on the spin. Spin dy-namics simulation studies are carried out for the JLEIC injector linac in order to preserve and maintain a high degree of polarization for light ion beams for delivery to the booster. The different options to maintain and restore the spin in the different sections of the linac for hydrogen, deuterium and helium ions are presented and discussed. Results from both the Zgoubi and COSY-Infinity codes are presented and compared for every section of the ion linac but the radio-frequency quadrupole (RFQ). Current-ly, a method to simulate the RFQ using Zgoubi is being investigated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLO02
About •	paper received ※ 28 August 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019
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WEPLM71	Thermal Performance of FRIB Cryomodules	cryomodule, cryogenics, cavity, operation	759
	M. Xu, W. Chang, C. Compton, A. Ganshyn, S.H. Kim, S.J. Miller, J.T. Popielarski, K. Saito, T. Xu FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and the National Science Foundation under Cooperative Agreement PHY-1102511. Now SRF cavity development is advancing high-Q/high gradient by nitrogen doping, infusion, or the new low temperature bake recipe. Once cavity dynamic loss is reduced, the static heat load of the cryomodule will be of concern from the cryogenic plant capability point of view. FRIB gives us a good chance to statistically compare the cryogenic plant design and the measured results, along with a thought for future updated cryomodule design using a low/medium beta cryomodule. FRIB cryomodules have two cooling lines: 4.5 K for solenoids and 2K for cavities. The boil-off liquid helium method was used to measure the cryomodule’s heat load. So far, FRIB has completed certification testing (bunker tests) on 39 of 49 cryomodules (80%). This paper reports the static heat load measurement results, which are important for future FRIB upgrades to estimate remaining cryogenic capability. The cryomodule’s evolution related to heat load is introduced too.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM71
About •	paper received ※ 05 September 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019
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WEPLM73	Bunker Testing of FRIB Cryomodules	cavity, cryomodule, SRF, dipole	765
	W. Chang, S. Caton, A. Ganshyn, W. Hartung, S.H. Kim, B. Laumer, H. Maniar, J.T. Popielarski, K. Saito, M. Xu, T. Xu, C. Zhang, S. Zhao FRIB, East Lansing, Michigan, USA
	The FRIB superconducting driver Linac requires 10⁴ quarter-wave resonators (QWRs, β = 0.041, 0.085), 220 half-wave resonators (HWRs, β = 0.29, 0.53), and 74 superconducting solenoid packages. Resonators and solenoids are assembled into cryomodules; 4 accelerating and 2 matching cryomodule types are required. Each cryomodule undergoes cryogenic and RF testing in a bunker prior to installation in the tunnel. The cryomodule test verifies operation of the cavities, couplers, tuners, solenoid packages, magnetic shield, and thermal shield at 4.3 K and 2 K. All of the required cryomodules for β = 0.041, 0.085, and 0.29 have been tested and certified. As of May 2019, five of the β = 0.53 cryomodules have been certified; the remaining modules are being assembled or are in the queue for testing. Cryomodule test results will be presented, including cavity performance (accelerating gradient, field emission X-rays, multipacting conditioning); solenoid package operation (current, current-lead cooling flow rate); and cryomodule heat load (static and dynamic).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM73
About •	paper received ※ 06 September 2019 paper accepted ※ 16 November 2020 issue date ※ 08 October 2019
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WEPLS12	A Semi-Analytical Approach to Six-Dimensional Path-Dependent Transport Matrices With Application to High-Brightness Charged-Particle Beam Transport	simulation, emittance, cavity, electron	792
	C.-Y. Tsai HUST, Wuhan, People’s Republic of China K. Fan Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China
	Funding: This work was supported by the Fundamental Research Funds for the Central Universities under Project No. 5003131049. Efficient and accurate estimate of high-brightness electron beam dynamics is an important step to the overall performance evaluation in modern particle accelerators. Utilizing the moment description to study multi-particle beam dynamics, it is necessary to develop a path-dependent transport matrix, together with application of the drift-kick algorithm. In this paper we will construct semi-analytical models for three typical beam transport elements, solenoid with fringe fields, transverse deflecting cavity, and a beam slit. To construct the semi-analytical models for these elements, we begin by formulating the simplified single-particle equations of motion, and apply typical numerical techniques to solve the corresponding six-by-six transport matrix as a function of the path coordinate. The developed semi-analytical models are demonstrated with three practical examples, where our numerical results are discussed, compared with and validated by particle tracking simulations. These path-dependent transport matrix models can be incorporated to the analysis based on beam matrix method for the application to high-brightness charged-particle beam transport. C.-Y. Tsai et al., Nuclear Inst. And Methods in Physics Research, A 937 (2019) 1-20
	Poster WEPLS12 [3.099 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS12
About •	paper received ※ 20 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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WEPLO12	Design of a PIP-II Era Mu2e Experiment	proton, target, experiment, collider	865
	M.A. Cummings, R.J. Abrams, T.J. Roberts Muons, Inc, Illinois, USA D.V. Neuffer Fermilab, Batavia, Illinois, USA
	We present an alternative Mu2e-II production scheme for the Fermilab PIP-II era based on production schemes we devised for muon-collider and neutrino-factory front ends. Bright muon beams generated from sources designed for muon collider and neutrino factory facilities have been shown to generate two orders of magnitude more muons per proton than the current Mu2e production target and solenoid. In contrast to the current Mu2e, the muon collider design has forward-production of muons from the target. Forward production from 8 GeV protons would include high energy antiprotons, pions and muons, which would provide too much background for the Mu2e system. In contrast, the 800 MeV PIP-II beam does not have sufficient energy to produce antiprotons, and other secondaries will be at a low enough energy that they can be ranged out with an affordable shield of ~ 2 meters of concrete.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLO12
About •	paper received ※ 01 September 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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WEPLE09	Mitigation of Nonlinear Phase Space in a Space-Charge-Limited Injector Diode	cathode, emittance, interface, focusing	905
	W.D. Stem, Y.-J. Chen, J. Ellsworth LLNL, Livermore, USA
	Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The performance of an accelerator is limited by the quality of the beam produced at the injector. For a Pierce-type diode structure, the cathode-shroud interface and the anode pipe entrance are sources for undesired, irreversible phase space nonlinearities that lead to emittance growth. In this contribution, we present ways to mitigate these nonlinearities by adjusting the cathode-shroud interface to meet the beam edge boundary conditions and by adjusting the solenoidal focusing magnet in the diode region such that the nonlinear focusing magnetic fringe fields compensate the nonlinear defocusing electrical fields of the anode pipe entrance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE09
About •	paper received ※ 05 September 2019 paper accepted ※ 04 December 2019 issue date ※ 08 October 2019
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THZBB6	Error Minimization in Transverse Phase-Space Measurements Using Quadrupole and Solenoid Scans	quadrupole, focusing, emittance, linac	971
	C.Y. Wong NSCL, East Lansing, Michigan, USA S.M. Lund FRIB, East Lansing, Michigan, USA
	Quadrupole and solenoid scans are common techniques where a series of beam profile measurements are taken under varying excitation of the linear focusing elements to unfold second-order phase-space moments of the beam at an upstream location. Accurate knowledge of the moments is crucial to machine tuning and understanding the underlying beam dynamics. The scans have many sources of errors including measurement errors, field errors and misalignments. The impact of these uncertainties on the moment measurement is often not analyzed. This study proposes a scheme motivated by linear algebra error bounds that can efficiently select a set of scan parameters to minimize the errors in measured initial moments. The results are verified via a statistical error analysis. These techniques are being applied at the Facility for Rare Isotope Beams (FRIB). We find that errors in initial moments can be large under conventional scans but are greatly reduced using the procedures described.
	Slides THZBB6 [2.153 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THZBB6
About •	paper received ※ 04 September 2019 paper accepted ※ 04 December 2019 issue date ※ 08 October 2019
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Paper

Title

Other Keywords

Page

MOZBB5

Magnetized Electron Source for JLEIC Cooler

cathode, electron, gun, high-voltage

83

R. Suleiman, P.A. Adderley, J.F. Benesch, D.B. Bullard, J.M. Grames, J. Guo, F.E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, G.A. Krafft, M.A. Mamun, M. Poelker, M.G. Tiefenback, Y.W. Wang, S. Zhang
JLab, Newport News, Virginia, USA
J.R. Delayen, G.A. Krafft, S.A.K. Wijethunga, J.T. Yoskowitz
ODU, Norfolk, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and supported by Laboratory Directed Research and Development funding.
Magnetized bunched-beam electron cooling is a critical part of the Jefferson Lab Electron Ion Collider (JLEIC). Strong cooling of ion beams will be accomplished inside a cooling solenoid where the ions co-propagate with an electron beam generated from a source immersed in magnetic field. This contribution describes the production and characterization of magnetized electron beam using a compact 300 kV DC high voltage photogun and bialkali-antimonide photocathodes. Beam magnetization was studied using a diagnostic beamline that includes viewer screens for measuring the shearing angle of the electron beamlet passing through a narrow upstream slit. Correlated beam emittance with magnetic field at the photocathode was measured for various laser spot sizes. Measurements of photocathode lifetime were carried out at different magnetized electron beam currents up to 28 mA and high bunch charge up to 0.7 nano-Coulomb was demonstrated.

Slides MOZBB5 [9.236 MB]

Poster MOZBB5 [1.564 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOZBB5

About •

paper received ※ 27 August 2019 paper accepted ※ 01 September 2019 issue date ※ 08 October 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPLH04

Design for HyRES Cathode Nanotip Electron Source

electron, cavity, gun, cathode

177

R.M. Hessami, A.F. Amhaz, P. Musumeci
UCLA, Los Angeles, USA

A new ultrafast electron diffraction (UED) instrument is being developed by UCLA-Colorado University collaboration for the STROBE NSF Center with the goal of using electron and EUV photon beams to reveal the structural dynamics of materials in non-equilibrium states at fundamental atomic and temporal scales. This paper describes the design of the electron beamline of this instrument. In order to minimize the initial emittance, a nanotip photocathode, 25 nm in radius, will be used. This requires a redesign of the cathode and anode components of the electron gun to allow for the tip to be properly aligned. Solenoidal lenses are used to focus the beam transversely to a sub-micron spot at the sample and a radiofrequency (RF) cavity, driven by a continuous wave S-band RF source, longitudinally compresses the beam to below 100 fs, required for atomic resolution.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLH04

About •

paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUYBA3

Benchmarking the LCLS-II Photoinjector

simulation, laser, gun, emittance

301

N.R. Neveu, T.J. Maxwell, C.E. Mayes
SLAC, Menlo Park, California, USA

Funding: DOE Contract No. DE-AC02-76SF00515
Commissioning of the LCLS-II photoinjector started in late 2018. Efforts to accurately model the gun and laser profiles is ongoing. Simulations of the photoinjector and solenoid are performed in ASTRA, IMPACT-T and OPAL-T. This work includes efforts to use the laser profile at the virtual cathode as the initial transverse beam distribution, and effects of 2D and 3D field maps. Beam size results are compared to experimental measurements taken at the YAG screen located after the gun.

Slides TUYBA3 [1.320 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUYBA3

About •

paper received ※ 29 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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TUZBA4

Interaction Region Magnets for Future Electron-Ion Collider at Jefferson Lab

quadrupole, electron, interaction-region, collider

345

R. Rajput-Ghoshal, C. Hutton, F. Lin, T.J. Michalski, V.S. Morozov, M. Wiseman
JLab, Newport News, Virginia, USA

The Jefferson Lab Electron Ion Collider (JLEIC) is a proposed new machine for nuclear physics research. It uses the existing CEBAF accelerator as a full energy injector to deliver 3 to 12 GeV electrons into a new electron collider ring. An all new ion accelerator and collider complex will deliver up to 200 GeV protons. The machine has luminosity goals of 10³⁴ cm^-2 ses⁻¹. The whole detector region including forward detection covers about 80 meters of the JLEIC complex. The interaction region design has recently been optimized to accommodate 200 GeV proton energy using conventional NbTi superconducting magnet technology. This paper will describe the requirements and preliminary designs for both the ion and electron beam magnets in the most complex 32 m long interaction region (IR) around the interaction point (IP). The interaction region has over thirty-seven superconducting magnets operating at 4.5K; these include dipoles, quadrupoles, skew-quadrupoles, solenoids, horizontal and vertical correctors and higher order multipole magnets. The paper will also discuss the electromagnetic interaction between these magnets.

Slides TUZBA4 [6.444 MB]

Poster TUZBA4 [1.549 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUZBA4

About •

paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019

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TUPLM07

First Experimental Observations of the Plasma-Cascade Instability in the CeC PoP Accelerator

electron, plasma, experiment, lattice

379

I. Petrushina
SUNY SB, Stony Brook, New York, USA
Y.C. Jing, V. Litvinenko, J. Ma, I. Pinayev, G. Wang, Y.H. Wu
BNL, Upton, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
K. Shih
SBU, Stony Brook, New York, USA

Preservation of the beam quality is important for attaining the desirable properties of the beam. Collective effects can produce an instability severely degrading beam emittance, momentum spread and creating filamentation of the beam. Microbunching instability for beams traveling along a curved trajectory, and space charge driven parametric transverse instabilities are well-known and in-depth studied. However, none of the above include a microbunching longitudinal instability driven by modulations of the transverse beam size. This phenomenon was observed for the first time during the commissioning of the CeC PoP experiment. Based on the dynamics of this instability we named it a Plasma-Cascade Instability (PCI). PCI can strongly intensify longitudinal micro-bunching originating from the beam’s shot noise, and even saturate it. Resulting random density and energy microstructures in the beam can become a serious problem for generating high quality electron beams. On the other hand, such instability can drive novel high-power sources of broadband radiation. In this paper we present our experimental observations of the PCI and the supporting results of the numerical simulations.

Poster TUPLM07 [17.319 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM07

About •

paper received ※ 27 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPLH03

Double-Bend Achromat Beamline for Injection Into a High-Power Superconducting Electron Linac

electron, gun, dipole, cavity

494

C.H. Boulware, T.L. Grimm, R. Hipple
Niowave, Inc., Lansing, Michigan, USA
S.M. Lund
FRIB, East Lansing, Michigan, USA
V.S. Morozov
JLab, Newport News, Virginia, USA

To take advantage of the high duty cycle operation of superconducting electron linacs, commercial systems use thermionic cathode electron guns that fill every RF bucket with an electron bunch. In continuous operation, the exit energy is limited when compared to pulsed systems. Bunch length and energy spread at the exit of the gun are incompatible with low losses in the superconducting cavity. A solenoid double-bend achromatic beamline is in operation at Niowave which allows energy and bunch length filtering of the beam leaving the gun before injection into the superconducting cavity. This system uses two solenoids and two dipoles to produce a round beam, using the edge angles of the dipoles to balance the focusing effects in the two transverse planes. The design allows beam filtering on the symmetry plane where the dispersion is maximum. Additionally, the bend angle moves the electron gun off the high-energy beam axis, allowing multiple-pass operation of the superconducting booster. This contribution will discuss the beam optics design of the double-bend achromat along with the design of the magnets and beam chambers and the operational experience with the system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH03

About •

paper received ※ 28 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019

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TUPLO02

Spin Dynamics in the JLEIC Ion Injector Linac

linac, proton, rfq, focusing

533

J.L. Martinez Marin, B. Mustapha
ANL, Lemont, Illinois, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: This work was supported by the U.S. DOE, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 for ANL and by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
One of the requirements for the future Electron Ion Col-lider (EIC) is to collide polarized electrons and light ions with at least 70% polarization for each beam. For light ions, polarized ion sources are used for injection to a linac, which is usually the first accelerator in the collider chain. The Jefferson Lab EIC (JLEIC) ion injector linac consists of a low-energy room-temperature section with quadrupole focusing followed by a superconducting linac with solenoid focusing inside long cryomodules. These two sections have different effects on the spin. Spin dy-namics simulation studies are carried out for the JLEIC injector linac in order to preserve and maintain a high degree of polarization for light ion beams for delivery to the booster. The different options to maintain and restore the spin in the different sections of the linac for hydrogen, deuterium and helium ions are presented and discussed. Results from both the Zgoubi and COSY-Infinity codes are presented and compared for every section of the ion linac but the radio-frequency quadrupole (RFQ). Current-ly, a method to simulate the RFQ using Zgoubi is being investigated.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLO02

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paper received ※ 28 August 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019

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WEPLM71

Thermal Performance of FRIB Cryomodules

cryomodule, cryogenics, cavity, operation

759

M. Xu, W. Chang, C. Compton, A. Ganshyn, S.H. Kim, S.J. Miller, J.T. Popielarski, K. Saito, T. Xu
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and the National Science Foundation under Cooperative Agreement PHY-1102511.
Now SRF cavity development is advancing high-Q/high gradient by nitrogen doping, infusion, or the new low temperature bake recipe. Once cavity dynamic loss is reduced, the static heat load of the cryomodule will be of concern from the cryogenic plant capability point of view. FRIB gives us a good chance to statistically compare the cryogenic plant design and the measured results, along with a thought for future updated cryomodule design using a low/medium beta cryomodule. FRIB cryomodules have two cooling lines: 4.5 K for solenoids and 2K for cavities. The boil-off liquid helium method was used to measure the cryomodule’s heat load. So far, FRIB has completed certification testing (bunker tests) on 39 of 49 cryomodules (80%). This paper reports the static heat load measurement results, which are important for future FRIB upgrades to estimate remaining cryogenic capability. The cryomodule’s evolution related to heat load is introduced too.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM71

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paper received ※ 05 September 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019

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WEPLM73

Bunker Testing of FRIB Cryomodules

cavity, cryomodule, SRF, dipole

765

W. Chang, S. Caton, A. Ganshyn, W. Hartung, S.H. Kim, B. Laumer, H. Maniar, J.T. Popielarski, K. Saito, M. Xu, T. Xu, C. Zhang, S. Zhao
FRIB, East Lansing, Michigan, USA

The FRIB superconducting driver Linac requires 10⁴ quarter-wave resonators (QWRs, β = 0.041, 0.085), 220 half-wave resonators (HWRs, β = 0.29, 0.53), and 74 superconducting solenoid packages. Resonators and solenoids are assembled into cryomodules; 4 accelerating and 2 matching cryomodule types are required. Each cryomodule undergoes cryogenic and RF testing in a bunker prior to installation in the tunnel. The cryomodule test verifies operation of the cavities, couplers, tuners, solenoid packages, magnetic shield, and thermal shield at 4.3 K and 2 K. All of the required cryomodules for β = 0.041, 0.085, and 0.29 have been tested and certified. As of May 2019, five of the β = 0.53 cryomodules have been certified; the remaining modules are being assembled or are in the queue for testing. Cryomodule test results will be presented, including cavity performance (accelerating gradient, field emission X-rays, multipacting conditioning); solenoid package operation (current, current-lead cooling flow rate); and cryomodule heat load (static and dynamic).

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM73

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paper received ※ 06 September 2019 paper accepted ※ 16 November 2020 issue date ※ 08 October 2019

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WEPLS12

A Semi-Analytical Approach to Six-Dimensional Path-Dependent Transport Matrices With Application to High-Brightness Charged-Particle Beam Transport

simulation, emittance, cavity, electron

792

C.-Y. Tsai
HUST, Wuhan, People’s Republic of China
K. Fan
Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China

Funding: This work was supported by the Fundamental Research Funds for the Central Universities under Project No. 5003131049.
Efficient and accurate estimate of high-brightness electron beam dynamics is an important step to the overall performance evaluation in modern particle accelerators. Utilizing the moment description to study multi-particle beam dynamics, it is necessary to develop a path-dependent transport matrix, together with application of the drift-kick algorithm*. In this paper we will construct semi-analytical models for three typical beam transport elements, solenoid with fringe fields, transverse deflecting cavity, and a beam slit. To construct the semi-analytical models for these elements, we begin by formulating the simplified single-particle equations of motion, and apply typical numerical techniques to solve the corresponding six-by-six transport matrix as a function of the path coordinate. The developed semi-analytical models are demonstrated with three practical examples, where our numerical results are discussed, compared with and validated by particle tracking simulations. These path-dependent transport matrix models can be incorporated to the analysis based on beam matrix method for the application to high-brightness charged-particle beam transport.
* C.-Y. Tsai et al., Nuclear Inst. And Methods in Physics Research, A 937 (2019) 1-20

Poster WEPLS12 [3.099 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS12

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paper received ※ 20 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019

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WEPLO12

Design of a PIP-II Era Mu2e Experiment

proton, target, experiment, collider

865

M.A. Cummings, R.J. Abrams, T.J. Roberts
Muons, Inc, Illinois, USA
D.V. Neuffer
Fermilab, Batavia, Illinois, USA

We present an alternative Mu2e-II production scheme for the Fermilab PIP-II era based on production schemes we devised for muon-collider and neutrino-factory front ends. Bright muon beams generated from sources designed for muon collider and neutrino factory facilities have been shown to generate two orders of magnitude more muons per proton than the current Mu2e production target and solenoid. In contrast to the current Mu2e, the muon collider design has forward-production of muons from the target. Forward production from 8 GeV protons would include high energy antiprotons, pions and muons, which would provide too much background for the Mu2e system. In contrast, the 800 MeV PIP-II beam does not have sufficient energy to produce antiprotons, and other secondaries will be at a low enough energy that they can be ranged out with an affordable shield of ~ 2 meters of concrete.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLO12

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paper received ※ 01 September 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019

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WEPLE09

Mitigation of Nonlinear Phase Space in a Space-Charge-Limited Injector Diode

cathode, emittance, interface, focusing

905

W.D. Stem, Y.-J. Chen, J. Ellsworth
LLNL, Livermore, USA

Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
The performance of an accelerator is limited by the quality of the beam produced at the injector. For a Pierce-type diode structure, the cathode-shroud interface and the anode pipe entrance are sources for undesired, irreversible phase space nonlinearities that lead to emittance growth. In this contribution, we present ways to mitigate these nonlinearities by adjusting the cathode-shroud interface to meet the beam edge boundary conditions and by adjusting the solenoidal focusing magnet in the diode region such that the nonlinear focusing magnetic fringe fields compensate the nonlinear defocusing electrical fields of the anode pipe entrance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE09

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paper received ※ 05 September 2019 paper accepted ※ 04 December 2019 issue date ※ 08 October 2019

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THZBB6

Error Minimization in Transverse Phase-Space Measurements Using Quadrupole and Solenoid Scans

quadrupole, focusing, emittance, linac

971

C.Y. Wong
NSCL, East Lansing, Michigan, USA
S.M. Lund
FRIB, East Lansing, Michigan, USA

Quadrupole and solenoid scans are common techniques where a series of beam profile measurements are taken under varying excitation of the linear focusing elements to unfold second-order phase-space moments of the beam at an upstream location. Accurate knowledge of the moments is crucial to machine tuning and understanding the underlying beam dynamics. The scans have many sources of errors including measurement errors, field errors and misalignments. The impact of these uncertainties on the moment measurement is often not analyzed. This study proposes a scheme motivated by linear algebra error bounds that can efficiently select a set of scan parameters to minimize the errors in measured initial moments. The results are verified via a statistical error analysis. These techniques are being applied at the Facility for Rare Isotope Beams (FRIB). We find that errors in initial moments can be large under conventional scans but are greatly reduced using the procedures described.

Slides THZBB6 [2.153 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THZBB6

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paper received ※ 04 September 2019 paper accepted ※ 04 December 2019 issue date ※ 08 October 2019

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