NLC Beam Phase Monitor
The NLC RF distribution system will need an electron beam phase reference to provide a long term stable phase reference. Three options are being considered to provide this reference (discussed in the LLRF meeting notes):
1. Measure the phase of the beam induced fields in the accelerator structure with the klystron RF power in that structure disabled. This method has the disadvantage of requiring structure RF to be taken off of the beam to allow phasing.
2. Measure the phase of the beam in the RF structure in the presence of the klystron RF. This method has the disadvantage of requiring extremely good phase measurement accuracy (<0.01degree X-band) for low beam currents.
3. Measure the beam phase with a separate RF cavity. This method has the disadvantage of requiring the addition of an additional RF cavity, and obtaining good long term phase stability of that cavity with respect to the accelerating structure.
A system to test method #1 has been installed in sector 30 of the SLC accelerator.
SLC phase measurement test setup
SLC phase measurement experimental results
Page by Josef Frisch frisch@slac.stanford.edu 04/22/2002
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