IPAC2018 - List of Authors (Warsop, C.M.)

Paper	Title	Page
TUPAL054	Experimental Measurements of Resonances near to the ISIS Working Point	1132
	P.T. Griffin-Hicks, B. Jones, B.G. Pine, C.M. Warsop, M. Wright STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is the pulsed spallation neutron source located at the Rutherford Appleton Laboratory in the UK. Operation is based on a 50 Hz, 800 MeV proton synchrotron, accelerating up to 3·10¹³ protons per pulse (ppp), which provides beam to two target stations. ISIS is beam loss limited, so to achieve greater beam intensity and optimal operation, losses must be reduced. Some beam loss may be attributed to resonance lines found in betatron tune space. These could be driven by higher order magnet field components, errors or misalignment. This paper describes work measuring losses against tune space around the ISIS working point. Experiments have been carried out to measure beam loss against tune in the ISIS synchrotron. The experiments were done at low intensity to minimise space charge and intensity effects. Resonance lines that cause beam loss can be clearly identified and provide new information about the machine. The experimental process has been automated in order to decrease experiment duration and to reduce systematic human error. MAD-X models that compare the beam envelope at different points in tune space to the beam pipe aperture are used to distinguish between losses caused by increased envelope size and losses induced by driven resonances.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL054
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TUPAL056	High Order Image Terms and Harmonic Closed Orbits at the ISIS Synchrotron	1140
	B.G. Pine, C.M. Warsop STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is the spallation neutron source at Rutherford Appleton Laboratory in the UK. Protons are accelerated from 70 to 800 MeV in a 50 Hz rapid cycling synchrotron. Due to the intense beam, space charge forces are high during the first part of the acceleration cycle. The vacuum vessel in the synchrotron has a rectangular shape where the apertures are conformal to the design beam envelopes. At high intensities image forces interact with the beam, especially when the closed orbit is large. An analysis of image forces has been made and used to classify higher order image terms. These have been identified using simulations of round beams in rectangular vacuum vessels. The higher order image terms from harmonic closed orbits have been used with single particle resonance theory, taking account of the coherent nature of the beam response. Several predictions of beam resonance have been made. A simulation study has been carried out using a smooth focusing lattice and uniform density beams. Resonant beam behaviour has been observed and explained by the proposed theory.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL056
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TUPAL058	Studies for Major ISIS Upgrades via Conventional RCS and Accumulator Ring Designs	1148
	C.M. Warsop, D.J. Adams, H.V. Cavanagh, P.T. Griffin-Hicks, B. Jones, B.G. Pine, R.E. Williamson STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK, which provides 0.2 MW of beam power via a 50 Hz, 800 MeV proton RCS. Detailed studies are now under way to find the optimal configuration for a next generation, short pulsed neutron source that will define a major ISIS upgrade in ~2031. Accelerator configurations being considered for the MW beam powers required include designs exploiting FFAG rings as well as conventional accumulator and synchrotron rings. This paper describes work exploring the latter, conventional options, but includes the possibility of pushing further toward intensity limits to reduce facility costs. The scope of planned studies is summarised, looking at optimal exploitation of existing ISIS infrastructure, and incorporating results from recent target studies and user consultations. Results from initial baseline studies for an accumulator ring and RCS located in the existing ISIS synchrotron hall are presented. Injection scheme, foil limits, longitudinal and transverse beam dynamics optimization with related beam loss and activation are outlined, as are results from detailed 3D PIC simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL058
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Experimental Measurements of Resonances near to the ISIS Working Point

1132

P.T. Griffin-Hicks, B. Jones, B.G. Pine, C.M. Warsop, M. Wright
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

ISIS is the pulsed spallation neutron source located at the Rutherford Appleton Laboratory in the UK. Operation is based on a 50 Hz, 800 MeV proton synchrotron, accelerating up to 3·10¹³ protons per pulse (ppp), which provides beam to two target stations. ISIS is beam loss limited, so to achieve greater beam intensity and optimal operation, losses must be reduced. Some beam loss may be attributed to resonance lines found in betatron tune space. These could be driven by higher order magnet field components, errors or misalignment. This paper describes work measuring losses against tune space around the ISIS working point. Experiments have been carried out to measure beam loss against tune in the ISIS synchrotron. The experiments were done at low intensity to minimise space charge and intensity effects. Resonance lines that cause beam loss can be clearly identified and provide new information about the machine. The experimental process has been automated in order to decrease experiment duration and to reduce systematic human error. MAD-X models that compare the beam envelope at different points in tune space to the beam pipe aperture are used to distinguish between losses caused by increased envelope size and losses induced by driven resonances.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL054

Export •

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

TUPAL056

High Order Image Terms and Harmonic Closed Orbits at the ISIS Synchrotron

1140

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

ISIS is the spallation neutron source at Rutherford Appleton Laboratory in the UK. Protons are accelerated from 70 to 800 MeV in a 50 Hz rapid cycling synchrotron. Due to the intense beam, space charge forces are high during the first part of the acceleration cycle. The vacuum vessel in the synchrotron has a rectangular shape where the apertures are conformal to the design beam envelopes. At high intensities image forces interact with the beam, especially when the closed orbit is large. An analysis of image forces has been made and used to classify higher order image terms. These have been identified using simulations of round beams in rectangular vacuum vessels. The higher order image terms from harmonic closed orbits have been used with single particle resonance theory, taking account of the coherent nature of the beam response. Several predictions of beam resonance have been made. A simulation study has been carried out using a smooth focusing lattice and uniform density beams. Resonant beam behaviour has been observed and explained by the proposed theory.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL056

Export •

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

TUPAL058

Studies for Major ISIS Upgrades via Conventional RCS and Accumulator Ring Designs

1148

C.M. Warsop, D.J. Adams, H.V. Cavanagh, P.T. Griffin-Hicks, B. Jones, B.G. Pine, R.E. Williamson
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK, which provides 0.2 MW of beam power via a 50 Hz, 800 MeV proton RCS. Detailed studies are now under way to find the optimal configuration for a next generation, short pulsed neutron source that will define a major ISIS upgrade in ~2031. Accelerator configurations being considered for the MW beam powers required include designs exploiting FFAG rings as well as conventional accumulator and synchrotron rings. This paper describes work exploring the latter, conventional options, but includes the possibility of pushing further toward intensity limits to reduce facility costs. The scope of planned studies is summarised, looking at optimal exploitation of existing ISIS infrastructure, and incorporating results from recent target studies and user consultations. Results from initial baseline studies for an accumulator ring and RCS located in the existing ISIS synchrotron hall are presented. Injection scheme, foil limits, longitudinal and transverse beam dynamics optimization with related beam loss and activation are outlined, as are results from detailed 3D PIC simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL058

Export •

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