FEL2011 - List of Authors (Shevchenko, O.A.)

Paper

Title

Page

Modeling of the Quiet Start Algorithm in the Framework of the Correlation Function Theory

99

O.A. Shevchenko, N. Vinokurov
BINP SB RAS, Novosibirsk, Russia

To suppress initial beam current fluctuations at the fundamental harmonic the macroparticle based FEL simulation codes use the quiet start algorithm. This algorithm should be valid at linear stage but there is no simple method to check whether it gives correct results at saturation. The regular approach to the start-up from noise problem should be based on the correlation function equation. In this paper we show that the quiet start algorithm can be naturally described in the framework of the correlation function theory. For this purpose one just needs to assume nonzero correlations in the initial particle distribution. This approach gives the possibility to compare simulation results for the system with reduced number of particles and artificially suppressed initial fluctuations with the case of real system with large number of particles.

WEOA3

Proof-of-principle Experiment for FEL-based Coherent Electron Cooling

322

V. Litvinenko, S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, A.V. Fedotov, Y. Hao, D. Kayran, G.J. Mahler, A. Marusic, G.T. McIntyre, W. Meng, M.G. Minty, I. Pinayev, V. Ptitsyn, T. Rao, T. Roser, B. Sheehy, S. Tepikian, R. Than, D. Trbojevic, J.E. Tuozzolo, G. Wang, V. Yakimenko
BNL, Upton, Long Island, New York, USA
D.T. Abell, G.I. Bell, D.L. Bruhwiler, C. Nieter, V.H. Ranjbar, B.T. Schwartz
Tech-X, Boulder, Colorado, USA
A. Hutton, G.A. Krafft, M. Poelker, R.A. Rimmer
JLAB, Newport News, Virginia, USA
M.A. Kholopov, O.A. Shevchenko, P. Vobly
BINP SB RAS, Novosibirsk, Russia
P.A. McIntosh, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron-hadron and electron-hadron colliders [1]. In a CEC system, a hadron beam interacts with a cooling electron beam. A perturbation of the electron density caused by ions is amplified and fed back to the ions to reduce the energy spread and the emittance of the ion beam. To demonstrate the feasibility of CEC we propose a proof-of-principle experiment at RHIC using one of JLab’s SRF cryo-modules. In this paper, we describe the experimental setup for CeC installed into one of RHIC's interaction regions. We present results of analytical estimates and results of initial simulations of cooling a gold-ion beam at 40 GeV/u energy via CeC.
[1] Vladimir N. Litvinenko, Yaroslav S. Derbenev, Physical Review Letters 102, 114801

Slides WEOA3 [3.568 MB]

WEPA11

Longitudinal Stability of ERL with Two Accelerating RF Structures

345

Ya.V. Getmanov, O.A. Shevchenko
BINP SB RAS, Novosibirsk, Russia
N. Vinokurov
NSU, Novosibirsk, Russia

Modern ERL projects use superconductive accelerating RF structures. Their RF quality is typically very high. Therefore, the RF voltage induced by electron beam is also high. In ERL the RF voltage induced by the accelerating beam is almost cancelled by the RF voltage induced by the decelerating beam. But, a small variation of the RF voltage may cause the deviations of the accelerating phases. These deviations then may cause further voltage variation. Thus the system may be unstable. The stability conditions for ERL with one accelerating structure are well known [1, 2]. The ERL with split RF structure was discussed recently [3, 4]. The stability conditions for such ERLs are discussed in this paper.
[1] L. Merminga et al., Annu. Rev. Nucl. Part. Sci. 53(2003) 387.
[2] N.A. Vinokurov et al., Proc. SPIE 2988 (1997) 221.
[3] D. Douglas, ICFA BD-Nl 26 (2001)40.
[4] N.A. Vinokurov et al., Proc. IPAC’10.

Paper	Title	Page
MOPC03	Modeling of the Quiet Start Algorithm in the Framework of the Correlation Function Theory	99
	O.A. Shevchenko, N. Vinokurov BINP SB RAS, Novosibirsk, Russia
	To suppress initial beam current fluctuations at the fundamental harmonic the macroparticle based FEL simulation codes use the quiet start algorithm. This algorithm should be valid at linear stage but there is no simple method to check whether it gives correct results at saturation. The regular approach to the start-up from noise problem should be based on the correlation function equation. In this paper we show that the quiet start algorithm can be naturally described in the framework of the correlation function theory. For this purpose one just needs to assume nonzero correlations in the initial particle distribution. This approach gives the possibility to compare simulation results for the system with reduced number of particles and artificially suppressed initial fluctuations with the case of real system with large number of particles.

WEOA3	Proof-of-principle Experiment for FEL-based Coherent Electron Cooling	322
	V. Litvinenko, S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, A.V. Fedotov, Y. Hao, D. Kayran, G.J. Mahler, A. Marusic, G.T. McIntyre, W. Meng, M.G. Minty, I. Pinayev, V. Ptitsyn, T. Rao, T. Roser, B. Sheehy, S. Tepikian, R. Than, D. Trbojevic, J.E. Tuozzolo, G. Wang, V. Yakimenko BNL, Upton, Long Island, New York, USA D.T. Abell, G.I. Bell, D.L. Bruhwiler, C. Nieter, V.H. Ranjbar, B.T. Schwartz Tech-X, Boulder, Colorado, USA A. Hutton, G.A. Krafft, M. Poelker, R.A. Rimmer JLAB, Newport News, Virginia, USA M.A. Kholopov, O.A. Shevchenko, P. Vobly BINP SB RAS, Novosibirsk, Russia P.A. McIntosh, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron-hadron and electron-hadron colliders [1]. In a CEC system, a hadron beam interacts with a cooling electron beam. A perturbation of the electron density caused by ions is amplified and fed back to the ions to reduce the energy spread and the emittance of the ion beam. To demonstrate the feasibility of CEC we propose a proof-of-principle experiment at RHIC using one of JLab’s SRF cryo-modules. In this paper, we describe the experimental setup for CeC installed into one of RHIC's interaction regions. We present results of analytical estimates and results of initial simulations of cooling a gold-ion beam at 40 GeV/u energy via CeC. [1] Vladimir N. Litvinenko, Yaroslav S. Derbenev, Physical Review Letters 102, 114801
	Slides WEOA3 [3.568 MB]

WEPA11	Longitudinal Stability of ERL with Two Accelerating RF Structures	345
	Ya.V. Getmanov, O.A. Shevchenko BINP SB RAS, Novosibirsk, Russia N. Vinokurov NSU, Novosibirsk, Russia
	Modern ERL projects use superconductive accelerating RF structures. Their RF quality is typically very high. Therefore, the RF voltage induced by electron beam is also high. In ERL the RF voltage induced by the accelerating beam is almost cancelled by the RF voltage induced by the decelerating beam. But, a small variation of the RF voltage may cause the deviations of the accelerating phases. These deviations then may cause further voltage variation. Thus the system may be unstable. The stability conditions for ERL with one accelerating structure are well known [1, 2]. The ERL with split RF structure was discussed recently [3, 4]. The stability conditions for such ERLs are discussed in this paper. [1] L. Merminga et al., Annu. Rev. Nucl. Part. Sci. 53(2003) 387. [2] N.A. Vinokurov et al., Proc. SPIE 2988 (1997) 221. [3] D. Douglas, ICFA BD-Nl 26 (2001)40. [4] N.A. Vinokurov et al., Proc. IPAC’10.