Low Level RF System Requirements

1
Low Level RF System Requirements

• Trent Allison, Hai Dong, Alicia Hofler
• Curt Hovater, Larry King, John Musson and Tomasz
  Plawski

2
RF Requirements

• Performance Requirements
• Operational Requirements
• In depth Information concerning these
  requirements can be found in
• Performance and Technical Requirements for
  the CEBAF Energy Upgrade Low Level RF System
• and the tech note RF PARAMETERS FOR THE 12
  GeV UPGRADE CRYOMODULE
• Project EHS

3
12 GeV Cryomodule LLRF Performance Requirement

• Tight cavity field control is needed to meet
  CEBAFs energy spread specification.

Original CEBAF Specifications
4
12 GeV Performance Requirements (contd)

• Cavity Fault Recovery 1 s
• Must compensate for large Lorentz detuning
  on cavity turn on.
• Cavity Interlocks RF drive should be inhibited
  within 10 us of fault detection
• Resonance Hunting LLRF system must quickly find
  the detuned cavity. Range /- 20 kHz. Time to
  bring a cavity back from a catastrophic detuning
  (CHL trip, initial detuning) is dependant of the
  stepper motor speed. A 20 kHz detuning should
  take 5 minutes.
• Active Resonance Control The PZT shall be on
  during CW operation maintaining resonance. Tuning
  accuracy is 2 Hz.

5
Operational Requirements

• Keep down-time low
• Intelligent diagnostics that can quickly isolate
  problem RF-cavity systems.
• Hot swappable
• History Buffers
• Incident (forward) RF Power
• Reflected RF Power
• Cavity Field
• I Q Drive Signals (I Q or phase amplitude)
• Internal Diagnostic Signals, e.g., loop error, as
  necessary for system setup
• At least 200 ms of waveform shall be
  displayed so that the cavity fill, beam-on/off,
  and cavity field decay can be observed. The
  display resolution shall be 2 us (100,000
  points). At least three of the five waveforms
  shall be displayable simultaneously.
• Fast Feedback/Feed Forward Analog inputs must
  have at least 10 kHz bandwidth .
• Interface to Distributed Event Trigger System

6
Project EHS

• Construction, Installation, Commissioning
  Maintenance Hazards
• Assembly Soldering and the use of sharp hand
  tools.
• Installation Sharp tools, Material Handling (19
  racks) confined work areas (19 racks).
• Commissioning Low voltage (lt15 vdc lt 50 A)
  electrical environment. Hazard Class I Mode
  1/2/3.
• No Exposed 120VAC and 150 Vdc (PZT) power .
• Maintenance Soldering and the use of sharp hand
  tools.
• Low voltage (lt15 vdc lt 50 A) electrical
  environment. Hazard Class I Mode 1/2/3.