HB2014 - List of Authors (Kornilov, V.)

Paper

Title

Page

Transverse Decoherence of Ion Bunches with Space Charge and Feedback System

45

I. Karpov
TEMF, TU Darmstadt, Darmstadt, Germany
O. Boine-Frankenheim, V. Kornilov
GSI, Darmstadt, Germany

The transverse decoherence of the bunch signal after an initial bunch displacement is an important process in synchrotrons and storage rings. It can be useful, for the diagnostic purposes, or undesirable. Collective bunch oscillations can appear after the bunch-to-bucket transfer between synchrotrons and can lead to the emittance blow-up. In order to preserve the beam quality and to control the emittance blow-up, transverse feedback systems (TFS) are used. But, TFS operation can also lead to emittance blow-up due to imperfections (noise, bandwidth limitation, time delay errors), which also depends on the TFS settings. In heavy ion and proton beams, like in SIS100 synchrotron of the FAIR project, transverse space charge strongly modify decoherence. The resulting transverse bunch decoherence and beam blow-up is due to a combination of the lattice settings (like chromaticity), nonlinearities (residual or imposed by octupole magnets), space-charge, and the TFS. We study these effects using particle tracking simulations with the objective of correct combinations for a controlled beam blow-up.

MOPAB38

Simulations of the Head-tail Instability on the ISIS Synchrotron

113

R.E. Williamson, D.J. Adams, B. Jones, C.M. Warsop
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
V. Kornilov
GSI, Darmstadt, Germany

ISIS is the pulsed spallation neutron and muon source at the Rutherford Appleton Laboratory in the UK. Operation is centred on a loss limited 50 Hz proton synchrotron which accelerates 3·10¹³ protons per pulse (ppp) from 70 MeV to 800 MeV, delivering a mean beam power of 0.2 MW. Present studies are focussed on key aspects of high intensity beam dynamics with a view to increasing operational intensity, understanding loss mechanisms and identifying possible upgrade routes. Of particular interest is the head-tail instability observed on ISIS, which is currently the main limitation on beam intensity. This paper presents initial simulations using HEADTAIL to compare with experimental data taken on the ISIS synchrotron. The details and assumptions of the impedance model and simulations are discussed. Plans for future head-tail measurements, simulations and analysis are outlined.

TUO3LR03

High Intensity Loss Mechanisms on the ISIS Rapid Cycling Synchrotron

203

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
V. Kornilov
GSI, Darmstadt, Germany

ISIS is the spallation neutron source at the Rutherford Appleton laboratory in the UK. Operation centres on a loss limited, 800 MeV, 50 Hz proton synchrotron which delivers 0.2 MW to two targets. Understanding loss mechanisms on the ISIS ring is important for optimal operation, machine developments and upgrades, as well as improving understanding for future machines. The high space charge levels, combined with the low loss achieved for high power operation, makes the ring an ideal tool for studying the physics of beam loss, particularly in a fast ramping context. The ability to reconfigure the beam in storage ring mode, and ongoing developments of diagnostics and beam measurements, are allowing detailed studies of image effects, resonances, beam stability and activation. We summarise recent work and progress on these topics, comparing with theory and simulation where appropriate.

Slides TUO3LR03 [2.534 MB]

WEO1LR02

Thresholds of the Head-Tail Instability in Bunches with Space Charge

240

V. Kornilov, O. Boine-Frankenheim
GSI, Darmstadt, Germany
D.J. Adams, B. Jones, B.G. Pine, C.M. Warsop, R.E. Williamson
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

Recent experimental studies of the unstable head-tail modes in the ISIS synchrotron (RAL, UK) provided intriguing findings about the intensity thresholds for the instability/stability along the acceleration ramp for different bunch parameters in single-rf and dual-rf operation. We explain the role of space-charge and the related Landau damping using particle tracking simulations and an airbag-bunch theory, and relate the observations to the classical single-rf, no space-charge theories in order to identify the driving impedances.

Slides WEO1LR02 [3.203 MB]

Paper	Title	Page
MOPAB11	Transverse Decoherence of Ion Bunches with Space Charge and Feedback System	45
	I. Karpov TEMF, TU Darmstadt, Darmstadt, Germany O. Boine-Frankenheim, V. Kornilov GSI, Darmstadt, Germany
	The transverse decoherence of the bunch signal after an initial bunch displacement is an important process in synchrotrons and storage rings. It can be useful, for the diagnostic purposes, or undesirable. Collective bunch oscillations can appear after the bunch-to-bucket transfer between synchrotrons and can lead to the emittance blow-up. In order to preserve the beam quality and to control the emittance blow-up, transverse feedback systems (TFS) are used. But, TFS operation can also lead to emittance blow-up due to imperfections (noise, bandwidth limitation, time delay errors), which also depends on the TFS settings. In heavy ion and proton beams, like in SIS100 synchrotron of the FAIR project, transverse space charge strongly modify decoherence. The resulting transverse bunch decoherence and beam blow-up is due to a combination of the lattice settings (like chromaticity), nonlinearities (residual or imposed by octupole magnets), space-charge, and the TFS. We study these effects using particle tracking simulations with the objective of correct combinations for a controlled beam blow-up.

MOPAB38	Simulations of the Head-tail Instability on the ISIS Synchrotron	113
	R.E. Williamson, D.J. Adams, B. Jones, C.M. Warsop STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom V. Kornilov GSI, Darmstadt, Germany
	ISIS is the pulsed spallation neutron and muon source at the Rutherford Appleton Laboratory in the UK. Operation is centred on a loss limited 50 Hz proton synchrotron which accelerates 3·10¹³ protons per pulse (ppp) from 70 MeV to 800 MeV, delivering a mean beam power of 0.2 MW. Present studies are focussed on key aspects of high intensity beam dynamics with a view to increasing operational intensity, understanding loss mechanisms and identifying possible upgrade routes. Of particular interest is the head-tail instability observed on ISIS, which is currently the main limitation on beam intensity. This paper presents initial simulations using HEADTAIL to compare with experimental data taken on the ISIS synchrotron. The details and assumptions of the impedance model and simulations are discussed. Plans for future head-tail measurements, simulations and analysis are outlined.

TUO3LR03	High Intensity Loss Mechanisms on the ISIS Rapid Cycling Synchrotron	203
	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 V. Kornilov GSI, Darmstadt, Germany
	ISIS is the spallation neutron source at the Rutherford Appleton laboratory in the UK. Operation centres on a loss limited, 800 MeV, 50 Hz proton synchrotron which delivers 0.2 MW to two targets. Understanding loss mechanisms on the ISIS ring is important for optimal operation, machine developments and upgrades, as well as improving understanding for future machines. The high space charge levels, combined with the low loss achieved for high power operation, makes the ring an ideal tool for studying the physics of beam loss, particularly in a fast ramping context. The ability to reconfigure the beam in storage ring mode, and ongoing developments of diagnostics and beam measurements, are allowing detailed studies of image effects, resonances, beam stability and activation. We summarise recent work and progress on these topics, comparing with theory and simulation where appropriate.
	Slides TUO3LR03 [2.534 MB]

WEO1LR02	Thresholds of the Head-Tail Instability in Bunches with Space Charge	240
	V. Kornilov, O. Boine-Frankenheim GSI, Darmstadt, Germany D.J. Adams, B. Jones, B.G. Pine, C.M. Warsop, R.E. Williamson STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	Recent experimental studies of the unstable head-tail modes in the ISIS synchrotron (RAL, UK) provided intriguing findings about the intensity thresholds for the instability/stability along the acceleration ramp for different bunch parameters in single-rf and dual-rf operation. We explain the role of space-charge and the related Landau damping using particle tracking simulations and an airbag-bunch theory, and relate the observations to the classical single-rf, no space-charge theories in order to identify the driving impedances.
	Slides WEO1LR02 [3.203 MB]