HB2016 - List of Authors (Jones, B.)

Paper	Title	Page
MOPR030	Simple Models for Beam Loss Near the Half Integer Resonance with Space Charge	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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MOPR031	Development of Physics Models of the ISIS Head-Tail Instability	155
	R.E. Williamson, B. Jones, C.M. Warsop STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is the pulsed spallation neutron and muon source at the Rutherford Appleton Laboratory in the UK. Operation centres on a rapid cycling proton synchrotron which accelerates 3·10¹³ protons per pulse (ppp) from 70 MeV to 800 MeV at 50 Hz, delivering a mean beam power of 0.2 MW. As a high intensity, loss-limited machine, research and development at ISIS is focused on understanding loss mechanisms with a view to improving operational performance and guiding possible upgrade routes. The head-tail instability observed on ISIS is of particular interest as it is currently a main limitation on beam intensity. Good models of impedance are essential for understanding instabilities and to this end, recent beam-based measurements of the effective transverse impedance of the ISIS synchrotron are presented. This paper also presents developments of a new, in-house code to simulate the head-tail instability observed and includes benchmarks against theory and comparisons with experimental results.
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TUPM3Y01	Operational Experience and Future Plans at ISIS	333
	D.J. Adams STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom I.S.K. Gardner, B. Jones, A.H. Kershaw, A.P. Letchford, R.J. Mathieson, A. Pertica, B.G. Pine, A. Seville, H. V. Smith, C.M. Warsop, R.E. Williamson, M. Wright STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	The ISIS spallation neutron and muon source has been in operation since 1984. The accelerator complex consists of an H⁻ ion source, 665 keV RFQ, 70 MeV linac, 800 MeV proton synchrotron and associated beam transfer lines. The facility currently delivers ~2.8·10¹³ protons per pulse (ppp) at 50 Hz, which is shared between two target stations. High intensity performance and operation are dominated by the need to minimise and control beam loss, which is key to sustainable machine operation, allowing essential hands on maintenance. The facility has had several upgrades including an RFQ, ring Second Harmonic RF system, key developments of diagnostics and instrumentation required for improving beam control and a Second Target station. Upgrades being installed, or expected in the near future, include: a ring damping system, a new injector MEBT with fast injection chopper and an upgraded 50 Hz target. Operational experience of ISIS and the impacts of its past and future upgrades are discussed. Ideas for major upgrades to ISIS are briefly reviewed, as are the underlying R&D projects.
	Slides TUPM3Y01 [2.902 MB]
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Paper

Title

Page

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

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

MOPR031

Development of Physics Models of the ISIS Head-Tail Instability

155

R.E. Williamson, B. Jones, C.M. Warsop
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

ISIS is the pulsed spallation neutron and muon source at the Rutherford Appleton Laboratory in the UK. Operation centres on a rapid cycling proton synchrotron which accelerates 3·10¹³ protons per pulse (ppp) from 70 MeV to 800 MeV at 50 Hz, delivering a mean beam power of 0.2 MW. As a high intensity, loss-limited machine, research and development at ISIS is focused on understanding loss mechanisms with a view to improving operational performance and guiding possible upgrade routes. The head-tail instability observed on ISIS is of particular interest as it is currently a main limitation on beam intensity. Good models of impedance are essential for understanding instabilities and to this end, recent beam-based measurements of the effective transverse impedance of the ISIS synchrotron are presented. This paper also presents developments of a new, in-house code to simulate the head-tail instability observed and includes benchmarks against theory and comparisons with experimental results.

Export •

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

TUPM3Y01

Operational Experience and Future Plans at ISIS

333

D.J. Adams
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
I.S.K. Gardner, B. Jones, A.H. Kershaw, A.P. Letchford, R.J. Mathieson, A. Pertica, B.G. Pine, A. Seville, H. V. Smith, C.M. Warsop, R.E. Williamson, M. Wright
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The ISIS spallation neutron and muon source has been in operation since 1984. The accelerator complex consists of an H⁻ ion source, 665 keV RFQ, 70 MeV linac, 800 MeV proton synchrotron and associated beam transfer lines. The facility currently delivers ~2.8·10¹³ protons per pulse (ppp) at 50 Hz, which is shared between two target stations. High intensity performance and operation are dominated by the need to minimise and control beam loss, which is key to sustainable machine operation, allowing essential hands on maintenance. The facility has had several upgrades including an RFQ, ring Second Harmonic RF system, key developments of diagnostics and instrumentation required for improving beam control and a Second Target station. Upgrades being installed, or expected in the near future, include: a ring damping system, a new injector MEBT with fast injection chopper and an upgraded 50 Hz target. Operational experience of ISIS and the impacts of its past and future upgrades are discussed. Ideas for major upgrades to ISIS are briefly reviewed, as are the underlying R&D projects.

Slides TUPM3Y01 [2.902 MB]

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