HB2016 - List of Keywords (resonance)

Paper	Title	Other Keywords	Page
MOAM6P60	Recent Progress of J-PARC MR Beam Commissioning and Operation	injection, operation, proton, kicker	21
	S. Igarashi KEK, Ibaraki, Japan
	The main ring (MR) of the Japan Proton Accelerator Research Complex (J-PARC) has been providing 30-GeV proton beams for elementary particle and nuclear physics experiments since 2009. The beam power of 390 kW has been recently achieved with 2·10¹⁴ protons per pulse and the cycle time of 2.48 s for the neutrino oscillation experiment. Main efforts in the beam tuning are to minimize beam losses and to localize the losses at the collimator section. Recent improvements include the 2nd harmonic rf operation to reduce the space charge effect with a larger bunching factor and corrections of resonances near the operation setting of the betatron tune. Because the beam bunches were longer with the 2nd harmonic rf operation, the injection kicker system was improved to accommodate the long bunches. We plan to achieve the target beam power of 750 kW in 2018 by making the cycle time faster to 1.3 s with new power supplies of main magnets, rf upgrade and improvement of injection and extraction devices. The possibility of the beam power beyond 750 kW is being explored with new settings of the betatron tune.
	Slides MOAM6P60 [9.968 MB]
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MOPR005	RF-Knockout Slow Extraction Design for XiPAF Synchrotron	extraction, septum, synchrotron, simulation	52
	H.J. Yao, X. Guan, G.R. Li, X.W. Wang, Q. Zhang, S.X. Zheng TUB, Beijing, People's Republic of China
	The physics design of slow extraction for Xi’an Proton Application Facility (XiPAF) synchrotron is discussed. The extraction scheme is composed of two resonant sextupoles, one electrostatic septum (ES) and two septum magnets. The phase space diagram under the Hardt condition at the entrance of ES and the last three turn’s trajectory before extraction are presented. A program is written with C++ to simulate slow extraction process by RF-knockout (RF-KO), the calculation results of dual frequency modulation (FM) and amplitude modulation (AM) are given, and the standard deviation of the fluctuation parameter R1 can be limited 0.2 with optimum parameters under a sampling frequency of about 10 kHz.
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MOPR010	Machine Element Contribution to the Longitudinal Impedance Model of the CERN SPS	impedance, simulation, coupling, pick-up	71
	T. Kaltenbacher, F. Caspers, C. Vollinger CERN, Geneva, Switzerland
	This contribution describes the current longitudinal impedance model of the SPS and studies carried out in order to improve, extend and update it. Specifically, new sources of impedances have been identified, evaluated and included in the model. One finding are low Q and low-frequency (LF; here below 1 GHz) resonances which occur due to enamelled flanges in combination with external cabling e.g. ground loops. These resonances couple to the beam through the gap with enamel coating which creates an open resonator. Since this impedance is important for beam stability in the CERN Proton Synchrotron (PS), RF by-passes were installed on the enamelled flanges, and their significance for the SPS beam is currently under investigation. Simulations, bench and beam measurements were used to deduce model parameters for beam dynamic simulations.
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MOPR020	Space Charge Effects of High Intensity Beams at BRing	emittance, simulation, injection, betatron	101
	J. Li, J.C. Yang IMP/CAS, Lanzhou, People's Republic of China
	Funding: Work supported by NSFC (Grant No. 11475235) Space charge effects perform one of the main intensity limitations for low energy synchrotron. Large tune spread and crossing resonance stop-bands can hardly be avoided for intensive heavy ion beam at high intensity. Several subjects like Betatron and structure resonance, and tune spread are discussed. Simulations are carried out for 238U³⁴⁺ focusing on emittance and intensity change during RF capture at the injection energy at the booster ring of the High Intensity heavy ion Accelerator Facility (HIAF). lijie@impcas.ac.cn
	Poster MOPR020 [1.157 MB]
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MOPR024	General Formula to Deduce the Space Charge Tune Spread From a Quadrupolar Pick-Up Measurement	space-charge, coupling, pick-up, kicker	120
	E. Métral CERN, Geneva, Switzerland
	In 1966, W. Hardt derived the oscillation frequencies obtained in the presence of space charge forces and gradients errors for elliptical beams. Since then, a simple formula is usually used to relate the shift of the quadrupolar mode (obtained from the quadrupolar pick-up) and the space charge tune spread, depending only on the ratio between the two transverse equilibrium beam sizes. However, this formula is not always valid, in particular for machines running close to the coupling resonance Qx = Qy with almost round beams. A new general formula is presented, giving the space charge tune spread as a function of i) the measured shift of the quadrupolar mode, ii) the ratio between the two transverse equilibrium beam sizes and iii) the distance between the two transverse tunes.
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MOPR026	Space Charge Mitigation With Longitudinally Hollow Bunches	space-charge, synchrotron, emittance, injection	130
	A. Oeftiger, S. Hancock, G. Rumolo CERN, Geneva, Switzerland
	Funding: CERN, Doctoral Studentship and EPFL, Doctorate Hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN's PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.
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MOPR029	On the Impact of Non-Symplecticity of Space Charge Solvers	space-charge, emittance, simulation, optics	146
	M. Titze CERN, Geneva, Switzerland
	Funding: German Federal Ministry of Education and Research (BMBF) To guarantee long-term reliability in the predictions of a numerical integrator, it is a well-known requirement that the underlying map has to be symplectic. It is therefore important to examine in detail the impact on emittance growth and noise generation in case this condition is violated. We present a strategy of how to tackle this question and some results obtained for particular PIC and frozen space charge models.
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MOPR030	Simple Models for Beam Loss Near the Half Integer Resonance with Space Charge	space-charge, simulation, lattice, coherent-effects	150
	C.M. Warsop, D.J. Adams, B. Jones, B.G. Pine STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	The half integer resonance is often used to define the high intensity limit of medium or low energy hadron rings where transverse space charge is significant. However, the mechanism leading to particle loss as beam approaches this resonance, which thus defines the limit, is not clearly understood. In this paper we explore simple models, based on single particle resonance ideas, to see if they describe useful aspects of motion as observed in simulations and experiments of 2D coasting beams on the ISIS synchrotron. Single particle behaviour is compared to 2D self-consistent models to assess when coherent motion begins to affect the single particle motion, and understand the relevance of coherent and incoherent resonance. Whilst the general problem of 2D resonant loss, with non-stationary distributions and non-linear fields is potentially extremely complicated, here we suggest that for a well-designed machine, where higher order pathological loss effects are avoided, a relatively simple model may give valuable insights into beam behaviour and control.
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MOPR034	Suppression of Half-Integer Resonance in Fermilab Booster	lattice, space-charge, booster, optics	164
	V.A. Lebedev, A. Valishev Fermilab, Batavia, Illinois, USA
	The particle losses at injection in the FNAL Booster are one of the major factors limiting the machine performance. The losses are caused by motion non-linearity due to direct space charge and due to non-linearity introduced by large values of chromaticity sextupoles required to suppress transverse instabilities. The report aims to address the former - the suppression of incoherent space charge effects by reducing deviations from the perfect periodicity of linear optics functions. It should be achieved by high accuracy optics measurements with subsequent optics correction and by removing known sources of optics perturbations. The study shows significant impact of optics correction on the half-integer stop band with subsequent reduction of particle loss. We use realistic Booster lattice model to understand the present limitations, and investigate the possible improvements which would allow high intensity operation with PIP-II parameters.
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MOPR036	Spin Tracking of Polarized Protons in the Main Injector at Fermilab	polarization, closed-orbit, lattice, proton	173
	M. Xiao Fermilab, Batavia, Illinois, USA C. Aldred, W. Lorenzon Michigan University, Ann Arbor, Michigan, USA
	The Main Injector (MI) at Fermilab currently produces high-intensity beams of protons at energies of 120 GeV for a variety of physics experiments. Acceleration of polarized protons in the MI would provide opportunities for a rich spin physics program at Fermilab. To achieve polarized proton beams in the Fermilab accelerator com-plex, shown in Fig.1.1, detailed spin tracking simulations with realistic parameters based on the existing facility are required. This report presents studies at the MI using a single 4-twist Siberian snake to determine the depolariz-ing spin resonances for the relevant synchrotrons. Results will be presented first for a perfect MI lattice, followed by a lattice that includes the real MI imperfections, such as the measured magnet field errors and quadrupole misa-lignments. The tolerances of each of these factors in maintaining polarization in the Main Injector will be discussed.
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MOPL011	Laser Stripping H⁻ Charge Exchange Injection by Femtosecond Lasers	laser, proton, injection, optics	212
	T.V. Gorlov ORNL, Oak Ridge, Tennessee, USA
	A new method for H⁻ laser assistant charge exchange injection using femtosecond laser pulses is considered. The existing method uses a divergent laser beam that allows compensation of angular and momentum spread of the stripped beam. The femtosecond laser pulse has a similar property that can compensate the spread and yield efficient laser stripping. Results of simulations with realistic femtosecond laser and H⁻ beam parameters are discussed. The proposed method may have some benefit for particular technical conditions compared with others.
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MOPL025	Transient Beam Loading Based Calibration for Cavity Phase and Amplitude Setting	cavity, beam-loading, linac, controls	250
	R. Zeng ESS, Lund, Sweden O. Troeng Lund University, Lund, Sweden
	Traditional phase scan method for cavity phase and amplitude setting is offline and hard to track the variations of environment and operation points. An alternative beam loading based calibration method is investigated in this paper, which might become useful online/real time calibration method.
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TUAM5X01	Space Charge Driven Beam Loss for Cooled Beams and Mitigation Measures in the CERN Low Energy Ion Ring	injection, ion, space-charge, sextupole	272
	H. Bartosik, S. Hancock, A. Huschauer, V. Kain CERN, Geneva, Switzerland
	The performance of the CERN Low Energy Ion Ring (LEIR) with electron cooled lead ion beams is presently limited by losses, which occur during RF capture and the first part of acceleration. Extensive experimental studies performed in 2015 indicate that the losses are caused by the interplay of betatron resonances and the direct space charge detuning, which is significantly enhanced during bunching. Mitigation measures have already been identified and successfully tested, such as reducing the peak line charge density after RF capture, i.e. increasing the rms longitudinal emittance, and compensating third order resonances using existing harmonic sextupole correctors. New record intensities at extraction have been achieved. This talk describes the main experimental results from the 2015 measurement campaign including already implemented mitigation measures and the proposed strategy for even further increasing the LEIR intensity reach in the future.
	Slides TUAM5X01 [8.803 MB]
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TUAM6X01	First Analysis of the Space Charge Effects on a Third Order Coupled Resonance	space-charge, emittance, synchrotron, simulation	278
	G. Franchetti GSI, Darmstadt, Germany S.S. Gilardoni, A. Huschauer, F. Schmidt, R. Wasef CERN, Geneva, Switzerland
	The effect of space charge on bunches stored for long term in a nonlinear lattice can be severe for beam survival. This may be the case in projects as SIS100 at GSI or LIU at CERN. In 2012, for the first time, the effect of space charge on a normal third order coupled resonance was investigated at the CERN-PS. The experimental results have highlighted an unprecedented asymmetric beam response: in the vertical plane the beam exhibits a thick halo, while the horizontal profile has only core growth. The quest for explaining these results requires a journey through the 4 dimensional dynamics of the coupled resonance investigating the fixed-lines, and requires a detailed code-experiment benchmarking also including beam profile benchmarking. This proceeding gives a short summary of the experimental results of the 2012 PS measurements, and address an interpretation based on the dynamics the fixed-lines.
	Slides TUAM6X01 [7.183 MB]
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WEAM1X01	Code Bench-Marking for Long-Term Tracking and Adaptive Algorithms	emittance, space-charge, simulation, experiment	357
	F. Schmidt, H. Bartosik, A. Huschauer, A. Oeftiger, M. Titze CERN, Geneva, Switzerland Y.I. Alexahin, J.F. Amundson, V.V. Kapin, E.G. Stern Fermilab, Batavia, Illinois, USA G. Franchetti GSI, Darmstadt, Germany J.A. Holmes ORNL, Oak Ridge, Tennessee, USA
	At CERN we have ramped up a program to investigate space charge effects in the LHC pre-injectors with high brightness beams and long storage times. This in view of the LIU upgrade project for these accelerators. These studies require massive simulation over large number of turns. To this end we have been looking at all available codes and started collaborations on code development with several laboratories: pyORBIT from SNS, SYNERGIA from Fermilab, MICROMAP from GSI and our in-house MAD-X code with an space charge upgrade. We have agreed with our collaborators to bench-mark all these codes in the framework of the GSI bench-marking suite, in particular the main types of frozen space charge and PIC codes are being tested. We also include a study on the subclass of purely frozen and the adaptive frozen modes both part of MAD-X in comparison with the purely frozen MICROMAP code. Last, we will report on CERN's code development effort to understand and eventually overcome the noise issue in PIC codes. J. Coupard et al., ‘‘LHC Injectors Upgrade, Technical Design Report, Vol. I: Protons'', LIU Technical Design Report (TDR), CERN-ACC-2014-0337.
	Slides WEAM1X01 [2.348 MB]
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THAM6X01	The Path to 1 MW: Beam Loss Control in the J-PARC 3-GeV RCS	injection, emittance, acceleration, power-supply	480
	H. Hotchi, H. Harada, S. Kato, M. Kinsho, K. Okabe, P.K. Saha, Y. Shobuda, F. Tamura, N. Tani, Y. Watanabe, K. Yamamoto, M. Yamamoto, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	The J-PARC 3-GeV RCS started 1-MW beam test from October 2014, and successfully achieved a 1-MW beam acceleration in January 2015. The most important issues in realizing such a high power routine beam operation are control and minimization of beam loss. This talk will present the recent progress of 1-MW beam tuning, especially focusing on our approaches to beam loss issues.
	Slides THAM6X01 [1.849 MB]
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THPM1X01	Typology of Space Charge Resonances	space-charge, emittance, lattice, focusing	486
	I. Hofmann GSI, Darmstadt, Germany
	The existence of structural space charge resonant effects in otherwise linear periodic focusing systems is well-known, but referred to in a variety of languages and contexts. We show here that for short bunched beams a ‘‘classification'' in two major groups is possible, e.g. parametric resonances or instabilities on the one hand and single particle type space charge resonances on the other hand. The primary feature of distinction is that for the former the driving space charge force initially exists on the noise level (rms or higher order mismatch) only and gets amplified parametrically, hence an entirely coherent response; for the latter the driving space charge multipole is part of the initial density profile and the coherent response is weak. In the extreme limit of KV beams only parametric resonances (instabilities) exist, and in principle in all orders. For waterbag or Gaussian distributions we find half-integer parametric resonances only up to fourth order, but evidence for single particle resonances in all orders up to tenth have been identified.
	Slides THPM1X01 [3.094 MB]
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THPM4X01	Resonances and Envelope Instability in High Intensity Linear Accelerators	lattice, space-charge, linac, emittance	491
	D. Jeon, J.-H. Jang, H. Jin IBS, Daejeon, Republic of Korea
	Funding: This work was supported by the Institute for Basic Science funded by the Ministry of Science, ICT and Future Planning (MSIP) and the NRF of Korea under Contract 2013M7A1A1075764. Understanding of space charge effects has grown and recent studies have led to the findings of resonances of high intensity linear accelerators. Lately the sixth order resonance of high intensity linear accelerators was reported, along with the in-depth studies on the fourth order resonance and the envelope instability. Experiment studies on space charge resonances were reported. This paper reviews the resonances of high intensity linear accelerators such as the 4σ =360deg, and the 6σ =720deg resonances, along with the envelope instability.
	Slides THPM4X01 [3.279 MB]
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FRAM2P01	Summary WG-A	space-charge, electron, simulation, experiment	575
	W. Fischer BNL, Upton, Long Island, New York, USA Y.H. Chin KEK, Ibaraki, Japan G. Franchetti GSI, Darmstadt, Germany
	Friday Summary
	Slides FRAM2P01 [6.325 MB]
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Paper

Title

Other Keywords

Page

MOAM6P60

Recent Progress of J-PARC MR Beam Commissioning and Operation

injection, operation, proton, kicker

21

S. Igarashi
KEK, Ibaraki, Japan

The main ring (MR) of the Japan Proton Accelerator Research Complex (J-PARC) has been providing 30-GeV proton beams for elementary particle and nuclear physics experiments since 2009. The beam power of 390 kW has been recently achieved with 2·10¹⁴ protons per pulse and the cycle time of 2.48 s for the neutrino oscillation experiment. Main efforts in the beam tuning are to minimize beam losses and to localize the losses at the collimator section. Recent improvements include the 2nd harmonic rf operation to reduce the space charge effect with a larger bunching factor and corrections of resonances near the operation setting of the betatron tune. Because the beam bunches were longer with the 2nd harmonic rf operation, the injection kicker system was improved to accommodate the long bunches. We plan to achieve the target beam power of 750 kW in 2018 by making the cycle time faster to 1.3 s with new power supplies of main magnets, rf upgrade and improvement of injection and extraction devices. The possibility of the beam power beyond 750 kW is being explored with new settings of the betatron tune.

Slides MOAM6P60 [9.968 MB]

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MOPR005

RF-Knockout Slow Extraction Design for XiPAF Synchrotron

extraction, septum, synchrotron, simulation

52

H.J. Yao, X. Guan, G.R. Li, X.W. Wang, Q. Zhang, S.X. Zheng
TUB, Beijing, People's Republic of China

The physics design of slow extraction for Xi’an Proton Application Facility (XiPAF) synchrotron is discussed. The extraction scheme is composed of two resonant sextupoles, one electrostatic septum (ES) and two septum magnets. The phase space diagram under the Hardt condition at the entrance of ES and the last three turn’s trajectory before extraction are presented. A program is written with C++ to simulate slow extraction process by RF-knockout (RF-KO), the calculation results of dual frequency modulation (FM) and amplitude modulation (AM) are given, and the standard deviation of the fluctuation parameter R1 can be limited 0.2 with optimum parameters under a sampling frequency of about 10 kHz.

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MOPR010

Machine Element Contribution to the Longitudinal Impedance Model of the CERN SPS

impedance, simulation, coupling, pick-up

71

T. Kaltenbacher, F. Caspers, C. Vollinger
CERN, Geneva, Switzerland

This contribution describes the current longitudinal impedance model of the SPS and studies carried out in order to improve, extend and update it. Specifically, new sources of impedances have been identified, evaluated and included in the model. One finding are low Q and low-frequency (LF; here below 1 GHz) resonances which occur due to enamelled flanges in combination with external cabling e.g. ground loops. These resonances couple to the beam through the gap with enamel coating which creates an open resonator. Since this impedance is important for beam stability in the CERN Proton Synchrotron (PS), RF by-passes were installed on the enamelled flanges, and their significance for the SPS beam is currently under investigation. Simulations, bench and beam measurements were used to deduce model parameters for beam dynamic simulations.

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MOPR020

Space Charge Effects of High Intensity Beams at BRing

emittance, simulation, injection, betatron

101

J. Li, J.C. Yang
IMP/CAS, Lanzhou, People's Republic of China

Funding: Work supported by NSFC (Grant No. 11475235)
Space charge effects perform one of the main intensity limitations for low energy synchrotron. Large tune spread and crossing resonance stop-bands can hardly be avoided for intensive heavy ion beam at high intensity. Several subjects like Betatron and structure resonance, and tune spread are discussed. Simulations are carried out for 238U³⁴⁺ focusing on emittance and intensity change during RF capture at the injection energy at the booster ring of the High Intensity heavy ion Accelerator Facility (HIAF).
lijie@impcas.ac.cn

Poster MOPR020 [1.157 MB]

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MOPR024

General Formula to Deduce the Space Charge Tune Spread From a Quadrupolar Pick-Up Measurement

space-charge, coupling, pick-up, kicker

120

E. Métral
CERN, Geneva, Switzerland

In 1966, W. Hardt derived the oscillation frequencies obtained in the presence of space charge forces and gradients errors for elliptical beams. Since then, a simple formula is usually used to relate the shift of the quadrupolar mode (obtained from the quadrupolar pick-up) and the space charge tune spread, depending only on the ratio between the two transverse equilibrium beam sizes. However, this formula is not always valid, in particular for machines running close to the coupling resonance Qx = Qy with almost round beams. A new general formula is presented, giving the space charge tune spread as a function of i) the measured shift of the quadrupolar mode, ii) the ratio between the two transverse equilibrium beam sizes and iii) the distance between the two transverse tunes.

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MOPR026

Space Charge Mitigation With Longitudinally Hollow Bunches

space-charge, synchrotron, emittance, injection

130

A. Oeftiger, S. Hancock, G. Rumolo
CERN, Geneva, Switzerland

Funding: CERN, Doctoral Studentship and EPFL, Doctorate
Hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN's PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

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MOPR029

On the Impact of Non-Symplecticity of Space Charge Solvers

space-charge, emittance, simulation, optics

146

M. Titze
CERN, Geneva, Switzerland

Funding: German Federal Ministry of Education and Research (BMBF)
To guarantee long-term reliability in the predictions of a numerical integrator, it is a well-known requirement that the underlying map has to be symplectic. It is therefore important to examine in detail the impact on emittance growth and noise generation in case this condition is violated. We present a strategy of how to tackle this question and some results obtained for particular PIC and frozen space charge models.

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MOPR030

Simple Models for Beam Loss Near the Half Integer Resonance with Space Charge

space-charge, simulation, lattice, coherent-effects

150

C.M. Warsop, D.J. Adams, B. Jones, B.G. Pine
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The half integer resonance is often used to define the high intensity limit of medium or low energy hadron rings where transverse space charge is significant. However, the mechanism leading to particle loss as beam approaches this resonance, which thus defines the limit, is not clearly understood. In this paper we explore simple models, based on single particle resonance ideas, to see if they describe useful aspects of motion as observed in simulations and experiments of 2D coasting beams on the ISIS synchrotron. Single particle behaviour is compared to 2D self-consistent models to assess when coherent motion begins to affect the single particle motion, and understand the relevance of coherent and incoherent resonance. Whilst the general problem of 2D resonant loss, with non-stationary distributions and non-linear fields is potentially extremely complicated, here we suggest that for a well-designed machine, where higher order pathological loss effects are avoided, a relatively simple model may give valuable insights into beam behaviour and control.

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MOPR034

Suppression of Half-Integer Resonance in Fermilab Booster

lattice, space-charge, booster, optics

164

V.A. Lebedev, A. Valishev
Fermilab, Batavia, Illinois, USA

The particle losses at injection in the FNAL Booster are one of the major factors limiting the machine performance. The losses are caused by motion non-linearity due to direct space charge and due to non-linearity introduced by large values of chromaticity sextupoles required to suppress transverse instabilities. The report aims to address the former - the suppression of incoherent space charge effects by reducing deviations from the perfect periodicity of linear optics functions. It should be achieved by high accuracy optics measurements with subsequent optics correction and by removing known sources of optics perturbations. The study shows significant impact of optics correction on the half-integer stop band with subsequent reduction of particle loss. We use realistic Booster lattice model to understand the present limitations, and investigate the possible improvements which would allow high intensity operation with PIP-II parameters.

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MOPR036

Spin Tracking of Polarized Protons in the Main Injector at Fermilab

polarization, closed-orbit, lattice, proton

173

M. Xiao
Fermilab, Batavia, Illinois, USA
C. Aldred, W. Lorenzon
Michigan University, Ann Arbor, Michigan, USA

The Main Injector (MI) at Fermilab currently produces high-intensity beams of protons at energies of 120 GeV for a variety of physics experiments. Acceleration of polarized protons in the MI would provide opportunities for a rich spin physics program at Fermilab. To achieve polarized proton beams in the Fermilab accelerator com-plex, shown in Fig.1.1, detailed spin tracking simulations with realistic parameters based on the existing facility are required. This report presents studies at the MI using a single 4-twist Siberian snake to determine the depolariz-ing spin resonances for the relevant synchrotrons. Results will be presented first for a perfect MI lattice, followed by a lattice that includes the real MI imperfections, such as the measured magnet field errors and quadrupole misa-lignments. The tolerances of each of these factors in maintaining polarization in the Main Injector will be discussed.

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MOPL011

Laser Stripping H⁻ Charge Exchange Injection by Femtosecond Lasers

laser, proton, injection, optics

212

T.V. Gorlov
ORNL, Oak Ridge, Tennessee, USA

A new method for H⁻ laser assistant charge exchange injection using femtosecond laser pulses is considered. The existing method uses a divergent laser beam that allows compensation of angular and momentum spread of the stripped beam. The femtosecond laser pulse has a similar property that can compensate the spread and yield efficient laser stripping. Results of simulations with realistic femtosecond laser and H⁻ beam parameters are discussed. The proposed method may have some benefit for particular technical conditions compared with others.

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MOPL025

Transient Beam Loading Based Calibration for Cavity Phase and Amplitude Setting

cavity, beam-loading, linac, controls

250

R. Zeng
ESS, Lund, Sweden
O. Troeng
Lund University, Lund, Sweden

Traditional phase scan method for cavity phase and amplitude setting is offline and hard to track the variations of environment and operation points. An alternative beam loading based calibration method is investigated in this paper, which might become useful online/real time calibration method.

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TUAM5X01

Space Charge Driven Beam Loss for Cooled Beams and Mitigation Measures in the CERN Low Energy Ion Ring

injection, ion, space-charge, sextupole

272

H. Bartosik, S. Hancock, A. Huschauer, V. Kain
CERN, Geneva, Switzerland

The performance of the CERN Low Energy Ion Ring (LEIR) with electron cooled lead ion beams is presently limited by losses, which occur during RF capture and the first part of acceleration. Extensive experimental studies performed in 2015 indicate that the losses are caused by the interplay of betatron resonances and the direct space charge detuning, which is significantly enhanced during bunching. Mitigation measures have already been identified and successfully tested, such as reducing the peak line charge density after RF capture, i.e. increasing the rms longitudinal emittance, and compensating third order resonances using existing harmonic sextupole correctors. New record intensities at extraction have been achieved. This talk describes the main experimental results from the 2015 measurement campaign including already implemented mitigation measures and the proposed strategy for even further increasing the LEIR intensity reach in the future.

Slides TUAM5X01 [8.803 MB]

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TUAM6X01

First Analysis of the Space Charge Effects on a Third Order Coupled Resonance

space-charge, emittance, synchrotron, simulation

278

G. Franchetti
GSI, Darmstadt, Germany
S.S. Gilardoni, A. Huschauer, F. Schmidt, R. Wasef
CERN, Geneva, Switzerland

The effect of space charge on bunches stored for long term in a nonlinear lattice can be severe for beam survival. This may be the case in projects as SIS100 at GSI or LIU at CERN. In 2012, for the first time, the effect of space charge on a normal third order coupled resonance was investigated at the CERN-PS. The experimental results have highlighted an unprecedented asymmetric beam response: in the vertical plane the beam exhibits a thick halo, while the horizontal profile has only core growth. The quest for explaining these results requires a journey through the 4 dimensional dynamics of the coupled resonance investigating the fixed-lines, and requires a detailed code-experiment benchmarking also including beam profile benchmarking. This proceeding gives a short summary of the experimental results of the 2012 PS measurements, and address an interpretation based on the dynamics the fixed-lines.

Slides TUAM6X01 [7.183 MB]

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WEAM1X01

Code Bench-Marking for Long-Term Tracking and Adaptive Algorithms

emittance, space-charge, simulation, experiment

357

F. Schmidt, H. Bartosik, A. Huschauer, A. Oeftiger, M. Titze
CERN, Geneva, Switzerland
Y.I. Alexahin, J.F. Amundson, V.V. Kapin, E.G. Stern
Fermilab, Batavia, Illinois, USA
G. Franchetti
GSI, Darmstadt, Germany
J.A. Holmes
ORNL, Oak Ridge, Tennessee, USA

At CERN we have ramped up a program to investigate space charge effects in the LHC pre-injectors with high brightness beams and long storage times. This in view of the LIU upgrade project for these accelerators. These studies require massive simulation over large number of turns. To this end we have been looking at all available codes and started collaborations on code development with several laboratories: pyORBIT from SNS, SYNERGIA from Fermilab, MICROMAP from GSI and our in-house MAD-X code with an space charge upgrade. We have agreed with our collaborators to bench-mark all these codes in the framework of the GSI bench-marking suite, in particular the main types of frozen space charge and PIC codes are being tested. We also include a study on the subclass of purely frozen and the adaptive frozen modes both part of MAD-X in comparison with the purely frozen MICROMAP code. Last, we will report on CERN's code development effort to understand and eventually overcome the noise issue in PIC codes.
J. Coupard et al., ‘‘LHC Injectors Upgrade,
Technical Design Report, Vol. I: Protons'', LIU Technical Design
Report (TDR), CERN-ACC-2014-0337.

Slides WEAM1X01 [2.348 MB]

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THAM6X01

The Path to 1 MW: Beam Loss Control in the J-PARC 3-GeV RCS

injection, emittance, acceleration, power-supply

480

H. Hotchi, H. Harada, S. Kato, M. Kinsho, K. Okabe, P.K. Saha, Y. Shobuda, F. Tamura, N. Tani, Y. Watanabe, K. Yamamoto, M. Yamamoto, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

The J-PARC 3-GeV RCS started 1-MW beam test from October 2014, and successfully achieved a 1-MW beam acceleration in January 2015. The most important issues in realizing such a high power routine beam operation are control and minimization of beam loss. This talk will present the recent progress of 1-MW beam tuning, especially focusing on our approaches to beam loss issues.

Slides THAM6X01 [1.849 MB]

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THPM1X01

Typology of Space Charge Resonances

space-charge, emittance, lattice, focusing

486

I. Hofmann
GSI, Darmstadt, Germany

The existence of structural space charge resonant effects in otherwise linear periodic focusing systems is well-known, but referred to in a variety of languages and contexts. We show here that for short bunched beams a ‘‘classification'' in two major groups is possible, e.g. parametric resonances or instabilities on the one hand and single particle type space charge resonances on the other hand. The primary feature of distinction is that for the former the driving space charge force initially exists on the noise level (rms or higher order mismatch) only and gets amplified parametrically, hence an entirely coherent response; for the latter the driving space charge multipole is part of the initial density profile and the coherent response is weak. In the extreme limit of KV beams only parametric resonances (instabilities) exist, and in principle in all orders. For waterbag or Gaussian distributions we find half-integer parametric resonances only up to fourth order, but evidence for single particle resonances in all orders up to tenth have been identified.

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THPM4X01

Resonances and Envelope Instability in High Intensity Linear Accelerators

lattice, space-charge, linac, emittance

491

D. Jeon, J.-H. Jang, H. Jin
IBS, Daejeon, Republic of Korea

Funding: This work was supported by the Institute for Basic Science funded by the Ministry of Science, ICT and Future Planning (MSIP) and the NRF of Korea under Contract 2013M7A1A1075764.
Understanding of space charge effects has grown and recent studies have led to the findings of resonances of high intensity linear accelerators. Lately the sixth order resonance of high intensity linear accelerators was reported, along with the in-depth studies on the fourth order resonance and the envelope instability. Experiment studies on space charge resonances were reported. This paper reviews the resonances of high intensity linear accelerators such as the 4σ =360deg, and the 6σ =720deg resonances, along with the envelope instability.

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FRAM2P01

Summary WG-A

space-charge, electron, simulation, experiment

575

W. Fischer
BNL, Upton, Long Island, New York, USA
Y.H. Chin
KEK, Ibaraki, Japan
G. Franchetti
GSI, Darmstadt, Germany

Friday Summary

Slides FRAM2P01 [6.325 MB]

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