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    Workshop on
    Low Level RF Controls for
    Superconducting Linacs

    April 25-27, 2001
    Jefferson Lab

    Dear Workshop Participant,

    Attached please find a proposed Working Group (WG) structure and proposed charges for each working group. The large number and wide variety of topics we want to cover in the Workshop dictates forming 3 parallel Working Groups. The broad topics to be covered by the Working Groups are:

    WG1: Conceptual designs for specific applications
    WG2: RF control schemes, rf modeling and rf system operation
    WG3: Implementation and design
    We understand that there is a strong overlap among all 3 groups, but especially between WG1 and WG2. Therefore we will start with a joined session of WG1 and WG2 and will split later.

    In order to make this a constructive Workshop, we will need to obtain feedback from you on the following areas:

    1. Which Working Group do you plan to join?
    2. What questions would you like to see answered?
    3. Have all topics of interest been covered? Would you recommend additional topics?

    We would highly recommend and encourage you to:

    1. Prepare a short presentation for use in the WGs (3-5 viewgraphs or more as needed) on the topics of your interest.
      Please make sure you notify us by April 6 on the title and contents of your presentation so we can include it in the agenda.
    2. Bring material related to your work and expertise in viewgraph or power point format, in order to facilitate efficient exchange of information within the working groups.
    Please communicate your response to Curt Hovater, or Lia Merminga

    Thank you very much. We look forward to hearing from you.


    Curt Hovater and Lia Merminga (JLAB)
    Stefan Simrock (DESY)

    Proposed Working Groups and their Charge

    Working Group 1 (WG1): Application Specific Issues and Conceptual Designs

    Charge of WG1:

    1. Compile a list of applications (e.g. SNS, RIA, TESLA, ERLs) and identify top level rf parameters (e.g. Ql , pulsed or cw, beam loading, low/high beta etc.).
    2. Write rf system requirements (e.g. required amplitude, phase and resonance control) and identify differences among different applications.
    3. Compile a list of various conceptual designs (e.g. Self Excited Loop (SEL), digital/analog/combination, generator-driven I/Q, amplitude/phase, etc.).
    4. Match up control designs/solutions with different applications. Identify pros and cons for each combination of application/design.
    5. Working group recommendations for each application.

    Working Group 2 (WG2): RF Field Control Schemes, RF System Modeling, RF

    System Operation

    Charge of WG2:

    1. Compile a list of possible algorithms, procedures and diagnostics for each conceptual design (as identified in Charge 3 of WG1). Start with a list of questions. Examples for questions to be answered:
      1. What are the different implementations of a SEL?
      2. Do we need piezo tuners in a high Ql cavity, what are the advantages, are they reliable?
      3. Feedforward (FF): when and where to implement. Issues specific to FF?
    2. How do we model an rf control system? Subsystem models for amplifiers, cavities, nonlinear effects, mechanical dynamics of the cavity, diagnostics (beam phase, detuning).
      1. Can we make a modeling menu?
      2. Can we develop a generic model applicable to the various schemes?
    3. Implementation (realization) of the model in a digital controller
    4. If possible compile a checklist which guides the rf system designer to the optimum design

    Working Group 3 (WG3): Implementation/Design

    Charge of WG3:

    1. Performance limitations of digital and analog designs
      1. Identify pros and cons
      2. Is analog still viable? Under what conditions?
      3. Software vs. hardware
    2. Industry standards vs. custom design:
      1. Identify state-of-the-art and future directions in electronic components
      2. In-house vs. out-of-house design
    3. DSP vs. FPGA vs. ASIC, at what cost?
    4. What is the best family/chip/chip set (Altera, Xlinx, AD, TI, Intersil, Motorola etc.) for your application?
    5. Reliability, maintainability, operability of low level rf control systems
    6. Automated operation of large scale rf systems
    7. Integration with other subsystems
    8. Global vs. local controls
    9. Calibration of rf system parameters

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