Brock transverse deflection

• The transverse deflection detection cavity I described is the same as Rimmer et al; coaxial, and transverse, but we don't need it to to be harmonic, so only one tuner (per side) is needed to un-insert/ insert the center coax. Also, in the sbir I showed two of these, nose to nose. This would allow us to measure 249.5MHz directly in this compact configuration (remember 750 is the third harmonic of what we are really after right?), and having two (operating as a single resonator) would allow us to adjust both noses to be equidistant from the beam.

• With the configuration shown in the proposal, nose to nose, resonant at 249.5 MHz. The cavity is unexcited by:

1. A perfectly centered 249.5 MHz beam.
2. A centered 499 MHz beam.
3. A centered imbalanced beam (more current in one 249.5 MHz beam than the other).
4. An off centered and balanced 499 MHz beam.

• The cavity is excited by:

1. An un-centered 249.5 beam
2. An imbalanced and un-centered 499 MHz beam
3. A 499 MHz beam with alternating deflection S-G deflection.

• So operating at 499 MHz there are only two ways to excite this cavity, one is with an imbalanced and un-centered beam, the other is by S-G deflection. Because the receiver measures both the amplitude of the cavity's excitation but also its phase with respect to a 249.5 MHz clock we can distinguish the two. This is done by using the Pockels cell to flip the polarization of both lasers at 1 kHz or so. The phase of the cavities detected excitation will flip with the Pockels cells only by S-G deflection!