IPAC2012 - List of Authors (Jones, R.M.)

Paper	Title	Page
TUPPR037	Simulations of Higher Order Modes in the ACC39 Module of FLASH	1900
	I.R.R. Shinton, R.M. Jones, P. Zhang UMAN, Manchester, United Kingdom Z. Li SLAC, Menlo Park, California, USA
	This study is primarily focused on the dipole component of the multiband expansion of the wakefield, with the emphasis being on the development of a HOM-based BPM system for ACC39 currently installed and in operation at FLASH and due to be installed at XFEL . Coupled inter-cavity modes are simulated together with a limited band of trapped modes. A suite of finite element computer codes (including HFSS and ACE3P) and globalised scattering matrix calculations (GSM) are used to investigate the modes in these cavities. In this way the nature of the multi-cavity nature of these modules is investigated with implications for a HOM-based BPM system and direct comparison to experimental results.

TUPPR039	Beam Dynamics Studies for the CLIC Main Linac	1903
	I. Nesmiyan, R.M. Jones UMAN, Manchester, United Kingdom A. Latina, D. Schulte CERN, Geneva, Switzerland
	Implications of the long-range wakefield on beam quality are investigated through a detailed beam dynamics study. Injection offsets are considered and the resulting emittance dilution recorded, including systematic and random sources of error. These simulations have been conducted for damped and detuned structures (DDS) and for waveguide damped structures–both for the CLIC collider.

WEPPR070	Beam Coupling Impedance Simulations of the LHC TCTP Collimators	3090
	H.A. Day, R.M. Jones UMAN, Manchester, United Kingdom F. Caspers, A. Dallocchio, L. Gentini, A. Grudiev, E. Métral, B. Salvant CERN, Geneva, Switzerland
	As part of an upgrade to the LHC collimation system, 8 TCTP and 1 TCSG collimators are proposed to replace existing collimators in the collimation system. In an effort to review all equipment placed in the accelerator complex for potential side effects due to collective effects and beam-equipment interactions, beam coupling impedance simulations are carried out in both the time-domain and frequency-domain of the full TCTP design. Particular attention is paid to trapped modes that may induce beam instabilities and beam-induced heating due to cavity modes of the device.

WEPPR071	Evaluation of the Beam Coupling Impedance of New Beam Screen Designs for the LHC Injection Kicker Magnets	3093
	H.A. Day, R.M. Jones UMAN, Manchester, United Kingdom M.J. Barnes, F. Caspers, H.A. Day, E. Métral, B. Salvant CERN, Geneva, Switzerland
	During the 2011 run of the LHC there was a measured temperature increase in the LHC Injection Kicker Magnets (LHC-MKI) during operation with 50ns bunch spacing. This was suspected to be due to increased beam-induced heating of the magnet due to beam impedance. Due to concerns about future heating with the increased total intensity to nominal and ultimate luminosities a review of the impedance reduction techniques within the magnet was required. A number of new beam screen designs are proposed and their impedance evaluated. Heating estimates are also given with a particular attention paid to future intensity upgrades to ultimate and HL-LHC parameters.

THPPC022	Enhanced Coupling Design of a Detuned Damped Structure for CLIC	3323
	A. D'Elia, A. Grudiev, V.F. Khan, W. Wuensch CERN, Geneva, Switzerland T. Higo KEK, Ibaraki, Japan R.M. Jones UMAN, Manchester, United Kingdom
	The key feature of the improved coupling design in the Damped Detuned Structure (DDS) is focused on the four manifolds. Rectangular geometry slots and rectangular manifolds are used. This results in a significantly stronger coupling to the manifolds compared to the previous design. We describe the new design together with its wakefield damping properties.

THPPC027	Measurement of the Dynamic Response of the CERN DC Spark System and Preliminary Estimates of the Breakdown Turn-on Time	3338
	N.C. Shipman, R.M. Jones UMAN, Manchester, United Kingdom S. Calatroni, W. Wuensch CERN, Geneva, Switzerland
	The new High Rep Rate (HRR) CERN DC Spark System has been used to investigate the current and voltage time structure of a breakdown. Simulations indicate that vacuum breakdowns develop on ns timescales or even less. An experimental benchmark for this timescale is critical for comparison to simulations. The fast rise time of breakdown may provide some explanation of the particularly high gradients achieved by low group velocity, and narrow bandwidth, accelerating structures such as the T18 and T24. Voltage and current measurements made with the previous system indicated that the transient responses measured were dominated by the inherent capacitances and inductances of the DC spark system itself. The bandwidth limitations of the HRR system are far less severe allowing rise times of around 12ns to be measured.

Paper

Title

Page

Simulations of Higher Order Modes in the ACC39 Module of FLASH

1900

I.R.R. Shinton, R.M. Jones, P. Zhang
UMAN, Manchester, United Kingdom
Z. Li
SLAC, Menlo Park, California, USA

This study is primarily focused on the dipole component of the multiband expansion of the wakefield, with the emphasis being on the development of a HOM-based BPM system for ACC39 currently installed and in operation at FLASH and due to be installed at XFEL . Coupled inter-cavity modes are simulated together with a limited band of trapped modes. A suite of finite element computer codes (including HFSS and ACE3P) and globalised scattering matrix calculations (GSM) are used to investigate the modes in these cavities. In this way the nature of the multi-cavity nature of these modules is investigated with implications for a HOM-based BPM system and direct comparison to experimental results.

TUPPR039

Beam Dynamics Studies for the CLIC Main Linac

1903

I. Nesmiyan, R.M. Jones
UMAN, Manchester, United Kingdom
A. Latina, D. Schulte
CERN, Geneva, Switzerland

Implications of the long-range wakefield on beam quality are investigated through a detailed beam dynamics study. Injection offsets are considered and the resulting emittance dilution recorded, including systematic and random sources of error. These simulations have been conducted for damped and detuned structures (DDS) and for waveguide damped structures–both for the CLIC collider.

WEPPR070

Beam Coupling Impedance Simulations of the LHC TCTP Collimators

3090

H.A. Day, R.M. Jones
UMAN, Manchester, United Kingdom
F. Caspers, A. Dallocchio, L. Gentini, A. Grudiev, E. Métral, B. Salvant
CERN, Geneva, Switzerland

As part of an upgrade to the LHC collimation system, 8 TCTP and 1 TCSG collimators are proposed to replace existing collimators in the collimation system. In an effort to review all equipment placed in the accelerator complex for potential side effects due to collective effects and beam-equipment interactions, beam coupling impedance simulations are carried out in both the time-domain and frequency-domain of the full TCTP design. Particular attention is paid to trapped modes that may induce beam instabilities and beam-induced heating due to cavity modes of the device.

WEPPR071

Evaluation of the Beam Coupling Impedance of New Beam Screen Designs for the LHC Injection Kicker Magnets

3093

H.A. Day, R.M. Jones
UMAN, Manchester, United Kingdom
M.J. Barnes, F. Caspers, H.A. Day, E. Métral, B. Salvant
CERN, Geneva, Switzerland

During the 2011 run of the LHC there was a measured temperature increase in the LHC Injection Kicker Magnets (LHC-MKI) during operation with 50ns bunch spacing. This was suspected to be due to increased beam-induced heating of the magnet due to beam impedance. Due to concerns about future heating with the increased total intensity to nominal and ultimate luminosities a review of the impedance reduction techniques within the magnet was required. A number of new beam screen designs are proposed and their impedance evaluated. Heating estimates are also given with a particular attention paid to future intensity upgrades to ultimate and HL-LHC parameters.

THPPC022

Enhanced Coupling Design of a Detuned Damped Structure for CLIC

3323

A. D'Elia, A. Grudiev, V.F. Khan, W. Wuensch
CERN, Geneva, Switzerland
T. Higo
KEK, Ibaraki, Japan
R.M. Jones
UMAN, Manchester, United Kingdom

The key feature of the improved coupling design in the Damped Detuned Structure (DDS) is focused on the four manifolds. Rectangular geometry slots and rectangular manifolds are used. This results in a significantly stronger coupling to the manifolds compared to the previous design. We describe the new design together with its wakefield damping properties.

THPPC027

Measurement of the Dynamic Response of the CERN DC Spark System and Preliminary Estimates of the Breakdown Turn-on Time

3338

N.C. Shipman, R.M. Jones
UMAN, Manchester, United Kingdom
S. Calatroni, W. Wuensch
CERN, Geneva, Switzerland

The new High Rep Rate (HRR) CERN DC Spark System has been used to investigate the current and voltage time structure of a breakdown. Simulations indicate that vacuum breakdowns develop on ns timescales or even less. An experimental benchmark for this timescale is critical for comparison to simulations. The fast rise time of breakdown may provide some explanation of the particularly high gradients achieved by low group velocity, and narrow bandwidth, accelerating structures such as the T18 and T24. Voltage and current measurements made with the previous system indicated that the transient responses measured were dominated by the inherent capacitances and inductances of the DC spark system itself. The bandwidth limitations of the HRR system are far less severe allowing rise times of around 12ns to be measured.