Joint PSP/Taskforce minutes for 21 Nov 2019
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slides posted to: http://beamdocs.fnal.gov/AD-public/DocDB/ShowDocument?docid=7839

(a) Updates from Tan for both PS and Task force
   (i) Status of PSP projects
      (1) H- test stand has new turbos. Penning source will be installed.
      (2) Klystron testing showed that pulse transformer in test stand
   is bad. Will be looked at internally first. If necessary sent out
   for repair. 
      (3) Adiabatic capture. ESME simulations show the reason why a
   neck is needed. Need to do studies to confirm.
      (4) 2 stage collimators. Have budget code to start drawings.
     (5) Injection absorber PDR review on 20 Nov. Review summary
   helpful.
     (6) Paraphase upgrade. Studies on 31 Oct showed that an
   independent phase control on B channel is needed.
   (iii) Task force
      (1) Dan Wolf, Howie Pfeffer or Chris Jensen will need to do a
   spice calculation because the replaced 4 gradient magnets might
   cuase an imbalance in GMPS.
     (2)  Digital LLRF. Meeting on 18 Oct showed there are potential
   problems with the injection scheme. Simulations are studies are
   needed to show scheme actually works.
     (3) 2 stage collimators. Task code has been supplied. Drawings started.
     (4) Wide aperture gradient magnets. Calculation of required
   aperture size completed. Will present after Thanksgiving.

(b) Joe showed the reason why beam loading compensation is required.
   (1) The required accelerating voltage for zero beam
   current is 746.5 kV
 	(i) If each cavity is able to provide 50 kV, for 22
   cavities, thre will be 1.1 MV available for acceleration.
   (2) The AC current at the RF frequency at 5GeV (53.438 MHz) is
   1.289 A. Joe used 82 bunches rather than 81 bunches for this calculation.
   (3) Assuming R/Q =50ohms, cavity voltage 50 kV, Joe found that the
   beam is Robinson unstable *without* beam loading compensation.
   (4) With beam loading compensation, and open loop gain of 1, the
   system becomes Robinson stable.
   (5) The beam loading compensation is a direct RF feedback system
   that requires a phase unwrap in the loop.

(c) Victor showed results from RF cavity busbars ramping at 20Hz
     (1) Tests showed that yard power for the bias supply is
     insufficient
	(i) East is at 100% rating
	(ii) West will need to have modulators removed from pulsed
     feeder.
     (2) Bus bar temperatures are too high.
     	 (i) Busbars at 20 Hz did not reach equilibrium. Experiment
     was terminated after temperature reached 100 degC after about 8
     hours. This is because polybeads melt at 120 degC. Temperature of
     busbar was still rising.
     (3) Remedies are all expensive
     	 (i) Change to water cooled bus bars
	 (ii) Change ferrite configuration in cavity tuners so that
     natural frequency is higher in PIPII
     	 (iii) Build new bias supplies so that the waveform terminates
     after between pulses.
     (4) Ioanis says that PIPII will pay for the yard
     breakers/transformers. This is because it was a PIPII risk.