Crab Cavity Development  (part of special projects group)    

The Crab Cavity system for the NLC final focus requires its two cavities to be phase matched to <0.2 degrees X-band. Slow phase difference drifts can be corrected by monitoring the beam position and adjusting the waveguide temperature, but fast differences need to be controlled by driving the cavities from a single klystron. We propose to use a second (low power if available) klystron to make small phase difference adjustments between the cavities as shown in the following diagram:

crab cavity diagram (canvas5format.CV5)

A prototype system should be constructed to test the phase stability of the system.

Drawing in Visio format, Parts List (ExcelFormat)

Alternate prototype system design using digital phase detection:

Drawing in Canvas5format.CV5

PowerPoint Slide presentation for Crab Cavity: crab.ppt

Phase noise calculations for the crab cavity control system: crabcalcs.pdf (frame maker source)

Crab cavity R+D schedule and cost for CDR schedule.xls

Recently a S-band crab cavity is being considered to reduce wake field effects. This would require 4X  tighter phase control, and probably 4X higher power. The test plan for this system would be similar, with the replacement of X-band components with S-band components.

Page by Josef Frisch frisch@slac.stanford.edu 04/22/2002