Author: Fedurin, M.G.
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(Aset - Aread )= 0.03dB, rms(Phiset - Phiread) = 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 icon 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