IPAC2011 - List of Authors (Yakimenko, V.)

Paper

Title

Page

Low RF Control Feedback and IQ Vector Modulator Compensation Functions

472

M.G. Fedurin, R. Malone, V. Yakimenko
BNL, Upton, Long Island, New York, USA

IQ vector modulator is key element of the gun and linac RF control circuits at Accelerator Test Facility at Brookhaven National Laboratory. IQ modulator calibration procedure was developed to find proper compensation functions in the conversion algorithm to minimize phase-amplitude coupling and setting-reading errors: rms(A_set - A_read )= 0.03dB, rms(Phi_set - Phi_read) = 0.3 deg. Since stabilization of the RF phase and amplitude is become critical for many experiments the slow feedback was developed and applied as well to significantly compensate drifts in RF system.

THOBA02

Experimental Demonstration of Suppression of Coherent Synchrotron Radiation Wake-field

V. Yakimenko, A.V. Fedotov, M.G. Fedurin, D. Kayran, V. Litvinenko
BNL, Upton, Long Island, New York, USA
P. Muggli
MPI, Muenchen, Germany

In this paper we report on a first experimental demonstration of coherent synchrotron radiation (CSR) wake-field suppression by a narrow-gap vacuum chamber. Increase in the beam energy spread and emittance due to emission of coherent synchrotron radiation (CSR) is considered to be a limiting factor a high-current high-brightness beams. At the Brookhaven National Laboratory Accelerator Test Facility (ATF) we experimentally demonstrated the suppression of CSR wake-field - both the average energy loss and he energy spread growth – using polished Al plates. Well characterized electron bunches were propagated through a bending magnet with two parallel Al plates with gap controlled between 1 mm to 12 mm. Contrary to some theoretic predictions, our experimental results show that closing the plates significantly reduces both the beam energy loss and CSR-induced beam energy spread. In this paper we present our experimental results and compare then with rigorous analytical theory. These results open a possibility to predict analytically CSR shielding of future high-current high-brightness beams.

Slides THOBA02 [12.706 MB]

THPC135

Optimal Parameters of the Photocathode Gun Space Charge to Improve Beam Quality

3203

M.G. Fedurin, C. Swinson, V. Yakimenko
BNL, Upton, Long Island, New York, USA

Accelerator Test Facility at Brookhaven National Laboratory operates with 5 MeV photocathode gun and 70 MeV linac for different range of experiments with a few picoseconds and a few micrometers emittance electron bunch. Many conducted experiments require beam with good spatial resolution and short length as well. NdYaG laser pulse turns to the electron bunch in the gun with space charge affecting on the own bunch length and transverse profile. Optimal beam loading parameters of the space charge in the photocathode RF gun could be found and used to improve bunch length and emittance. Simple model and experimental results on the Accelerator Test Facility at Brookhaven national Laboratory will be described

THPS009

Coherent Electron Cooling Demonstration Experiment

3442

V. Litvinenko, S.A. Belomestnykh, I. Ben-Zvi, J. Bengtsson, A.V. Fedotov, Y. Hao, D. Kayran, G.J. Mahler, W. Meng, T. Rao, T. Roser, B. Sheehy, R. Than, J.E. Tuozzolo, G. Wang, V. Yakimenko
BNL, Upton, Long Island, New York, USA
G.I. Bell, D.L. Bruhwiler, 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, P. Vobly
BINP SB RAS, Novosibirsk, Russia

Coherent electron cooling (CEC) is considered to be on of potential candidates capable of cooling high-energy, high-intensity hadron beams to very small emittances. It also has a potential to significantly boost luminosity of high-energy hadron-hadron and electron-hadron colliders. In a CEC system, a perturbation of the electron density caused by a hadron is amplified and fed back to the hadrons to reduce the energy spread and the emittance of the beam. Following the funding decision by DoE office of Nuclear Physics, we are designing and building coherent electron cooler for a proof-of-principle experiment at RHIC to cool 40 GeV heavy ion beam. In this paper, we describe the layout of the CeC installed into IP2 interaction region at RHIC. We present the design of the CeC cooler and results of preliminary simulations.

Paper	Title	Page
MOPC166	Low RF Control Feedback and IQ Vector Modulator Compensation Functions	472
	M.G. Fedurin, R. Malone, V. Yakimenko BNL, Upton, Long Island, New York, USA
	IQ vector modulator is key element of the gun and linac RF control circuits at Accelerator Test Facility at Brookhaven National Laboratory. IQ modulator calibration procedure was developed to find proper compensation functions in the conversion algorithm to minimize phase-amplitude coupling and setting-reading errors: rms(A_set - A_read )= 0.03dB, rms(Phi_set - Phi_read) = 0.3 deg. Since stabilization of the RF phase and amplitude is become critical for many experiments the slow feedback was developed and applied as well to significantly compensate drifts in RF system.

THOBA02	Experimental Demonstration of Suppression of Coherent Synchrotron Radiation Wake-field
	V. Yakimenko, A.V. Fedotov, M.G. Fedurin, D. Kayran, V. Litvinenko BNL, Upton, Long Island, New York, USA P. Muggli MPI, Muenchen, Germany
	In this paper we report on a first experimental demonstration of coherent synchrotron radiation (CSR) wake-field suppression by a narrow-gap vacuum chamber. Increase in the beam energy spread and emittance due to emission of coherent synchrotron radiation (CSR) is considered to be a limiting factor a high-current high-brightness beams. At the Brookhaven National Laboratory Accelerator Test Facility (ATF) we experimentally demonstrated the suppression of CSR wake-field - both the average energy loss and he energy spread growth – using polished Al plates. Well characterized electron bunches were propagated through a bending magnet with two parallel Al plates with gap controlled between 1 mm to 12 mm. Contrary to some theoretic predictions, our experimental results show that closing the plates significantly reduces both the beam energy loss and CSR-induced beam energy spread. In this paper we present our experimental results and compare then with rigorous analytical theory. These results open a possibility to predict analytically CSR shielding of future high-current high-brightness beams.
	Slides THOBA02 [12.706 MB]

THPC135	Optimal Parameters of the Photocathode Gun Space Charge to Improve Beam Quality	3203
	M.G. Fedurin, C. Swinson, V. Yakimenko BNL, Upton, Long Island, New York, USA
	Accelerator Test Facility at Brookhaven National Laboratory operates with 5 MeV photocathode gun and 70 MeV linac for different range of experiments with a few picoseconds and a few micrometers emittance electron bunch. Many conducted experiments require beam with good spatial resolution and short length as well. NdYaG laser pulse turns to the electron bunch in the gun with space charge affecting on the own bunch length and transverse profile. Optimal beam loading parameters of the space charge in the photocathode RF gun could be found and used to improve bunch length and emittance. Simple model and experimental results on the Accelerator Test Facility at Brookhaven national Laboratory will be described

THPS009	Coherent Electron Cooling Demonstration Experiment	3442
	V. Litvinenko, S.A. Belomestnykh, I. Ben-Zvi, J. Bengtsson, A.V. Fedotov, Y. Hao, D. Kayran, G.J. Mahler, W. Meng, T. Rao, T. Roser, B. Sheehy, R. Than, J.E. Tuozzolo, G. Wang, V. Yakimenko BNL, Upton, Long Island, New York, USA G.I. Bell, D.L. Bruhwiler, 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, P. Vobly BINP SB RAS, Novosibirsk, Russia
	Coherent electron cooling (CEC) is considered to be on of potential candidates capable of cooling high-energy, high-intensity hadron beams to very small emittances. It also has a potential to significantly boost luminosity of high-energy hadron-hadron and electron-hadron colliders. In a CEC system, a perturbation of the electron density caused by a hadron is amplified and fed back to the hadrons to reduce the energy spread and the emittance of the beam. Following the funding decision by DoE office of Nuclear Physics, we are designing and building coherent electron cooler for a proof-of-principle experiment at RHIC to cool 40 GeV heavy ion beam. In this paper, we describe the layout of the CeC installed into IP2 interaction region at RHIC. We present the design of the CeC cooler and results of preliminary simulations.