Author: Olsen, J.J.
Paper Title Page
MOPC28 The Hardware Implementation of the CERN SPS Ultrafast Feedback Processor Demonstrator 124
 
  • J.E. Dusatko, J.M. Cesaratto, J.D. Fox, J.J. Olsen, C.H. Rivetta
    SLAC, Menlo Park, California, USA
  • W. Höfle
    CERN, Geneva, Switzerland
 
  Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research program ( LARP)
An ultrafast 4GSa/s transverse feedback processor has been developed for proof-of-concept studies of feedback control of e-cloud driven and transverse mode coupled intra-bunch instabilities in the CERN SPS. This system consists of a high-speed ADC on the front end and equally fast DAC on the back end. All control and signal processing is implemented in FPGA logic. This system is capable of taking up to 16 sample slices across a single SPS bunch and processing each slice individually within a reconfigurable signal processor. This demonstrator system is a rapidly developed prototype, consisting of both commercial and custom-design components. It can stabilize the motion of a single particle bunch using closed loop feedback. The system can also run open loop as a high-speed arbitrary waveform generator and contains diagnostic features including a special ADC snapshot capture memory. This paper describes the overall system, the feedback processor and focuses on the hardware architecture, design and implementation.
 
poster icon Poster MOPC28 [1.684 MB]  
 
MOPC41 Engineering Design of the New LCLS X-band Transverse Deflecting Cavity 167
 
  • P. Krejcik, E.L. Bong, M. Boyes, S. Condamoor, J.P. Eichner, G.L. Gassner, A.A. Haase, B. Hong, B. Morris, J.J. Olsen, D.W. Sprehn, J.W. Wang
    SLAC, Menlo Park, California, USA
 
  Funding: This work was supported by Department of Energy Contract No. DE-AC0276SF00515
This paper describes the engineering design and installation of the new X-band transverse deflecting cavity installed downstream of the FEL undulator at the LCLS. This is a companion submission to the paper “Commissioning the New LCLS X-Band Transverse Deflecting Cavity with Femtosecond Resolution” also presented at this conference. The project dealt with the challenge of installing a new high-power RF system in the undulator tunnel of the LCLS, outside of the linac tunnel itself and its accelerator engineering infrastructure. A description of the system design, installation, alignment, cooling, controls, vacuum, waveguide, low level RF, klystron and modulator systems for the XTCAV is given, with emphasis on achieving the performance goals necessary to achieve femtosecond resolution.
 
 
TUBL2 A 4 GS/s Feedback Processing System for Control of Intra-Bunch Instabilities 323
 
  • J.D. Fox, J.M. Cesaratto, J.E. Dusatko, J.J. Olsen, K.M. Pollock, C.H. Rivetta, O. Turgut
    SLAC, Menlo Park, California, USA
  • W. Höfle
    CERN, Geneva, Switzerland
 
  Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research program ( LARP)
We present the architecture and implementation overview of a digital signal processing system developed to study control of Electron-Cloud and Transverse Mode coupling instabilities in the CERN SPS. The system is based on a reconfigurable processing architecture which samples vertical bunch motion and applies correction signals at a 4 GS/s rate, allowing 16 samples across a single 5 ns SPS RF bucket. The system requires wideband beam pickups and a vertical kicker structure with GHz bandwidth. This demonstration system implements a general purpose 16 tap FIR control filter for each sample. We present results from SPS machine studies showing the impact of wideband feedback to excite/damp internal modes of vertical motion as well as stabilize an unstable beam. These results highlight the challenges of intra-bunch feedback and show proof of principle feasibility of the architecture.
 
slides icon Slides TUBL2 [12.154 MB]  
 
WEPC23 Design of an Ultra-Compact Stripline BPM Receiver using MicroTCA for LCLS-II at SLAC 731
 
  • C. Xu, S. Babel, S. L. Hoobler, R.S. Larsen, J.J. Olsen, S.R. Smith, T. Straumann, D. Van Winkle, A. Young
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by U.S. Department of Energy under Contract Numbers DE-AC02-06CH11357 and DE-AC02-76SF00515
The Linac Coherent Light Source II (LCLS II) is a free electron laser (FEL) light source. LCLS II will be able to produce 0.5 to 77 Angstroms soft and hard x-rays. In order to achieve this high level of performance, the electron beam needs to be stable and accurate. The LCLS II stripline BPM system has a dynamic range of 10pC to 1nC beam charge. The system has a 3.5 micrometer resolution at 250pC beam charge in an one inch diameter stripline BPM structure. The BPM system uses the MicroTCA physics platform that consists of analog front-end (AFE) and 16-bit analog to digital convertor (ADC) module. The paper will discuss the hardware design, architecture, and performance measurements on the SLAC LINAC. The hardware architecture includes bandpass filter at 300MHz with 15 MHz band-width, and BPM calibration process without communicating with the CPU module. The system will be able to process multibunch beams with 40ns spacing.
 
poster icon Poster WEPC23 [1.769 MB]  
 
WEPC24 Performance Measurements of the New X-Band Cavity BPM Receiver 735
 
  • A. Young, J.E. Dusatko, S. L. Hoobler, J.J. Olsen, T. Straumann
    SLAC, Menlo Park, California, USA
  • C. Kim
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  Funding: Work supported by U.S. Department of Energy under Contract Numbers DE-AC02-06CH11357 and DE-AC02-76SF00515
SLAC is developing a new X-band Cavity BPM receiver for use in the LCLS-II. The Linac Coherent Light Source II (LCLS-II) will be a free electron laser (FEL) at SLAC producing coherent 0.5-77 Angstroms hard and soft x-rays. To achieve this level of performance precise, stable alignment of the electron beam in the undulator is required. The LCLS-II cavity BPM system will provide single shot resolution better than 50 nm resolution at 200 pC*. The Cavity BPM heterodyne receiver is located in the tunnel close to the cavity BPM. The receiver will processes the TM010 monopole reference cavity signal and a TM110 dipole cavity signal at approximately 11 GHz using a heterodyne technique. The heterodyne receiver will be capable of detecting a multibunch beam with a 50ns fill pattern. A new LAN communication daughter board will allow the receiver to talk to an input-output-controller (IOC) over 100 meters to set gains, control the phase locked local oscillator, and monitor the status of the receiver. We will describe the design methodology including noise analysis, Intermodulation Products analysis.
* Commissioning and Performance of LCLS Cavity BPMs, Stephen Smith, et al., Proc. of PAC 2009
 
poster icon Poster WEPC24 [0.251 MB]