CD-ILC briefing with Young-Kee Kim

1
CD-ILC briefing with Young-Kee Kim

• Low Level RF (LLRF) project for ILCTA and ILC

2
What is Low Level RF?

• Low power RF circuits and feedback controls,
  including
• Master oscillator (MO) and Local Oscillator (LO)
• The MO provides the 1.3GHz reference for all RF
  components.
• The LO provides a frequency slightly higher/lower
  than the MO frequency used to shift the cavity
  probe signal in the frequency domain.
• RF down-converters
• Convert the cavity probe signal spectrum to an
  Intermediate Frequency (IF) domain.
• Timing hardware
• Time accelerator related events such as the start
  of a beam pulse.
• Cavity controller
• Controls the power delivered by the klystron to
  the cavities.
• LLRF is a key subject for Fermilab in ILC.
• LLRF requires relatively small MS but lots of
  manpower.

3
Simplified LLRF block diagram (for CC2 system)
Timing (All digital)
Low frequency Sophisticated control DSP
RF frequencies
Back to RF frequencies
4
LLRF Cavity controller

• The LLRF controller is the brain of the LLRF
  system.
• One LLRF controller controls one klystron which
  powers 24 cavities (i.e. 3 cryomodules 1 LLRF
  station)
• 24 cavity prove voltages are averaged by the
  controller.
• Current specifications for ILC cavity gradient
  control
• 0.5 amplitude, 0.03º phase.
• 0.5 amplitude, 0.5º phase for ILCTA.
• Required from the LLRF controller
• Instrumentation precision electronics (i.e. very
  low noise -150dBm/vHz).
• Long list of algorithms to be developed and
  implemented in firmware and software (i.e. for
  FPGAs and microprocessors).
• Communication interface with slow-controls.

5
LLRF collaboration

• Fermilab LLRF is a collaboration of 3 divisions
  AD,TD,CD.
• LLRF project leaders Ruben Carcagno, Brian
  Chase, Gustavo Cancelo.
• CD effort in LLRF for ILCTA and ILC
• 3.7 FTEs for 06, 4 FTEs requested to GDE for
  07.
• AMR, CEPA CSS collaborators (e.g. Treptow,
  Haynes, Kwarciany, Zmuda, Deuerling, Wilcer,
  Cancelo, Bledsoe, etc.)
• Other collaborators
• DESY
• UPENN
• INFN-Pisa
• INFN-Milano
• PhD students (Helen Edwards program).

6
Current LLRF activities at Fermilab
CC2 at Meson

• A0 photo-injector and CC1.
• CC2 at Meson lab (1.7 ºK)
• Vertical test facility at IB1.
• Piezo tuner sensor actuator.
• Lorentz force detuning control.
• Cavity mechanical resonant modes measured.
• Current LLRF activities based on DESY hardware
  and software.
• Lots of effort in understanding and debugging
  DESY parts.

7
RF studies with CC2

• 31.5 MV/m achieved.
• Note oscillations due to 42 HZ microphonics
  detuning.
• Manual coupler conditioning.
• Cavity multipacting studies.

8
LLRF system in close mode using Simcon 3.1
controller
9
DOOCS control software from DESY

• CC2 system working in closed loop

10
FNAL-CD centric LLRF activities

• Design of a new LLRF controller (10 channels)
• Will replace current controller designed by DESY.
  Performance improvement expected.
• Design and implementation of a new I-Q detector
  at 50MHz to improve the input signal to noise
  ratio.
• LLRF models and control strategies
• Cavity electrical and mechanical models, Lorentz
  force and microphonics detuning, klystron
  nonlinear models, feedback and feedforward
  control strategies. PhD student (A.Paytyan,
  G.Cancelo).
• Lots of growing potential for this field. (RD).
• Simulation at the cavity level, cryomodule level
  (8 cavities), LLRF station level (24 cavities),
  up to the whole LINAC.
• Interfaces with other CD groups working in
  simulations.
• Man power requested.

11
FNAL-CD centric LLRF activities

• Implementation of algorithms in FPGAs
• We are exploring a new concept using a high level
  language that allows behavioral and gate level
  simulations in the same environment.
• Calibration algorithms (future activity).
• Field vector calibration.
• Input and output rotation matrices.
• Loop gain calibration.
• Loop phase calibration.
• Klystron linearization.
• Detuning calculation.
• Q loaded calculation.
• Beam phase and gradient calibration.
• Slow control interface
• boundary needs to be defined, so far controls
  group doing all the work.

12
LLRF future activities at Fermilab

• Support of ILCTA areas
• Control of 1 cryomodule.
• Control of 2 and 3 cryomodules.
• Could use 3 x 10-channel LLRF controllers but at
  some point we would like to build a 24 to 32
  input controller for ILC.
• Horizontal test facility
• Photo-injector moving from A0 to Muon Lab ??
• Other LLRF components to be developed
• Piezo-tuner control hardware and software.
• Cavity motor controller.
• Forward and reflected power monitors.
• RF system supervision (e.g. klystron signals,
  reference, beam intensity, etc).
• Vector modulators
• Multichannel down-converters.

13
Summary

• LLRF for ILC is a very enjoyable intellectual
  challenge that includes
• Accelerator physics and engineering modeling.
• Accelerator beam and cavity measurements.
• Algorithm design.
• Micro and macro level simulations.
• Feedback, feed-forward, and adaptive control and
  parameter estimation.
• High quality hardware design.
• RF electronics.
• Firmware and software design
• LLRF project must do RD and support ILCTA
  concurrently.