HB2012 - List of Authors (Payne, S.J.)

Paper

Title

Page

Simulation and Measurement of Half Integer Resonance in Coasting Beams in the ISIS Ring

434

C.M. Warsop, D.J. Adams, B. Jones, S.J. Payne, B.G. Pine, H. V. Smith, 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. Operation centres on a high intensity proton synchrotron, accelerating 3·10¹³ ppp from 70-800 MeV, at a repetition rate of 50 Hz. Present studies are looking at key aspects of high intensity behaviour with a view to increasing operational intensity, identifying optimal upgrade routes and understanding loss mechanisms. Of particular interest is the space charge limit imposed by half integer resonance: we present results from coasting beam experiments with the ISIS ring in storage ring mode, along with detailed 3D (ORBIT) simulations to help interpret observations. The methods for experimentally approaching resonance, and the implications on beam behaviour, measurement and interpretation are discussed. In addition, results from simpler 2D simulations and analytical models are used to help interpret expected beam loss and halo evolution. Plans and challenges for the measurement and understanding of this important beam loss mechanism are summarised, as are some closely related areas of high intensity work on ISIS.

Slides WEO1C02 [2.224 MB]

THO1C02

Beam Loss Control in the ISIS Accelerator Facility

560

D.J. Adams, B. Jones, A.H. Kershaw, S.J. Payne, B.G. Pine, 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, RFQ, 70 MeV linac, 800 MeV proton synchrotron and associated beam lines. The facility currently delivers ~2.8·10¹³ protons per pulse at 50 Hz, splitting the pulses 40/10 between two neutron target stations. High intensity performance and operation are dominated by the need to control beam loss, which is key to sustainable machine operation and hands on maintenance. Beam loss measurement systems on ISIS are described, along with typical operational levels. The dominant beam loss in the facility occurs in the synchrotron due to high intensity effects during the H⁻ injection and longitudinal trapping processes. These losses are localised in a single superperiod using a beam collector system. Emittance growth during acceleration also drives extraction and beam transport loss at 800 MeV. Measurements, simulation and correction systems for these processes are discussed, as are the implications for further intensity upgrades.

Slides THO1C02 [4.759 MB]

Paper	Title	Page
WEO1C02	Simulation and Measurement of Half Integer Resonance in Coasting Beams in the ISIS Ring	434
	C.M. Warsop, D.J. Adams, B. Jones, S.J. Payne, B.G. Pine, H. V. Smith, 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. Operation centres on a high intensity proton synchrotron, accelerating 3·10¹³ ppp from 70-800 MeV, at a repetition rate of 50 Hz. Present studies are looking at key aspects of high intensity behaviour with a view to increasing operational intensity, identifying optimal upgrade routes and understanding loss mechanisms. Of particular interest is the space charge limit imposed by half integer resonance: we present results from coasting beam experiments with the ISIS ring in storage ring mode, along with detailed 3D (ORBIT) simulations to help interpret observations. The methods for experimentally approaching resonance, and the implications on beam behaviour, measurement and interpretation are discussed. In addition, results from simpler 2D simulations and analytical models are used to help interpret expected beam loss and halo evolution. Plans and challenges for the measurement and understanding of this important beam loss mechanism are summarised, as are some closely related areas of high intensity work on ISIS.
	Slides WEO1C02 [2.224 MB]

THO1C02	Beam Loss Control in the ISIS Accelerator Facility	560
	D.J. Adams, B. Jones, A.H. Kershaw, S.J. Payne, B.G. Pine, 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, RFQ, 70 MeV linac, 800 MeV proton synchrotron and associated beam lines. The facility currently delivers ~2.8·10¹³ protons per pulse at 50 Hz, splitting the pulses 40/10 between two neutron target stations. High intensity performance and operation are dominated by the need to control beam loss, which is key to sustainable machine operation and hands on maintenance. Beam loss measurement systems on ISIS are described, along with typical operational levels. The dominant beam loss in the facility occurs in the synchrotron due to high intensity effects during the H⁻ injection and longitudinal trapping processes. These losses are localised in a single superperiod using a beam collector system. Emittance growth during acceleration also drives extraction and beam transport loss at 800 MeV. Measurements, simulation and correction systems for these processes are discussed, as are the implications for further intensity upgrades.
	Slides THO1C02 [4.759 MB]