Cornell University Unit Name

Experimental Log for the May 22-26 Kicker Test at the A0 Photoinjector

Monday 22 May

• Arrive around lunch
• A0 experienced a failed Traveling Wave Amplifier (TWA) this morning
  • Problems with replacement
  • Repair and testing ongoing
• Start initial setup
• DAQ checkout underway by Michael Davidsaver

Tuesday 23 May

• Look at voltage induced on pulser due to beam
  • Find that coupling in both directions cause similar peak signal level
  • Directionally coupled signal has the exepcted doublet
  • Signal in the wrong direction has a peak and ringing
• Pulser roughly timed in to look at beam
  • Find that DG535 precision delay generator cannot run at 1 MHz when programmed with large delay values
    • According to Jamie Santucci this is a known problem
    • JS provides a selectable cable delay box that will allow the DG535 delay to be shortened and full BW pulsing to take place.
• Continued checks of DAQ by MD
• Encounter persistent problems with TWA trips
• Take initial timing scan data to identify pulse edges and peak of kick
• Initial analysis of BPM data shows that BPM 7 data has offset positions which appear quantized. Suspect bit problem with that detector.

Wednesday 24 May

• Kicker Timing: KTRIG0 = 1445 to have pulser in time

Thursday 25 May

• DAQ program (/home/a0pi/davidsav/daqattack/daqattack) modified for better attenuation control algorithm
  • Observe better behavior
  • Note that attenuators have to be lowered significantly when kicking the beam
• Scraping Issues: Appear to be scraping on the kicker at full kick strength
• Adjust upstream corrector to improve kicker transmission with kicker on: HTAX14: -0.2 Amps --> 0.68 Amps
• Attenuator Settings measured for
  1. straight through beam after adjusting quads Q2AX14 and Q3AX14
  2. With kicking on (and in time)
  3. Adjust upstream H corrector HTAXU2 from 0 to 2 Amps
  4. Take kicker out of time
  5. Repeat of 1

     BPM	Atten NO kick	Atten w/kick	Atten w/kick & HTAXU2	Atten w/HTAXU2 only	Atten NO Kick
     4	16	15	16	15	15
     5	16	15	15	15	15
     6	15	14	15	14	14
     7	16	16	16	15	16
     9	18	17	17	17	17
     10	13	15	14	12	12
     11	14	11	12	1	13
     12	17	16	17	2	17

• Take run 81 with kicker out of time (KTRIG0 = 1446, 1 microsecond late)
• Still having problems with the attenuator values displayed in the daqattack program (although BPMs appear to have valid. Appears to have been an initialization problem in the code.
• Runs 82-84 are test runs
• Run 85 is a straight through run (KTRIG0 = 1446)
• Run 86 is a kicker peak run (KTRIG0 = 1445, Delay=15.5 ns, HTAXU2 = 2.0 Amps). High statistics.

• 1400 MD puts in a reset fix if BPMs readback at 0 for 20 times, resets the BPM.
• Inadvertently appended 64 events to end of file 86 on A0pi
• Files 87-88 are diagnostics
• Trigger cables and drive have been changed for the pulser which has changed the delay somewhat. Pulser delay now needs to be about 14.5 ns).
• File 89 with kicker running. See huge beam fluctuations and trajectory change. Find that we have 9-cell problems.
• Proceed with 9-cell adjustments and redo tune-up. (Current in quads = 1611)
• Jamie arrives with pulse generator for driving FID pulser. This change going in simultaneously with 9-cell work. Puts delay timing back to the original 15.5 ns based on scope comparison of beam doublet and pulser waveform.
• Files 90 and 91 are tune-up. Had to adjust spectrum analyzer magnet.
• File 92 is a kicking test. Lost first two BPMs at end. Shows better stability so triggering was an issue
• File 93 is a repeat of 92. Similar resolution.
• Files 94 - xx are a timing scan.

  File	KTRIG0	Delay	HTAXU2	Comment
  94	1445	12.5ns	0.923	Setting up
  95	1445	12.5ns	0.923	Data point
  96	1445	13.5ns	1.758	Setting up
  97	1445	13.5ns	1.758	Data point
  98	1445	14.5ns	2.202	Setting up
  99	1445	14.5ns	2.202	Data point
  100	1445	15.5ns	1.758	Setting up
  101	1445	15.5ns	1.758	Data point

• Observe possible 9-cell problem. Stop scan for diagnostics/re-tune
  • Cavity: Reset feedback loop and adjust phase
  • Possible cryogenics problem
• Return to scan

  File	KTRIG0	Delay	HTAXU2	Comment
  102	1445	14.25ns	2.202	Data point
  103	1445	14.5ns	2.202	Data point
  104	1445	14.75ns	2.202	Data point
  105	1445	15.0ns	2.202	Data point
  106	1445	15.5ns	1.758	Data point
  107	1445	16.5ns	0.923	Data point
  108	1445	17.5ns	0.0	Data point
  109	1445	17.0ns	0.500	Setting up
  110	1445	17.0ns	0.500	Data point
  111	1445	18.0ns	0.0	Data point
  112	1445	19.0ns	0.0	Data point
  113	1445	20.0ns	0.0	Data point
  114	1445	21.0ns	0.0	Data point
  115	1445	22.0ns	0.0	Data point
  116	1445	8.5ns	0.0	Data point
  117	1445	9.5ns	0.0	Data point
  118	1445	10.5ns	0.0	Data point
  119	1445	11.5ns	0.0	Data point
  120	1445	12.0ns	0.500	Data point
  121	1445	12.5ns	0.923	Data point
  122	1445	13.0ns	1.250	Data point
  123	1445	16.0ns	1.250	Data point
  124	1445	13.5ns	1.758	Data point
  125	1445	14.0ns	2.202	Data point
  126	1445	14.5ns	2.202	Data point
  127	1445	14.4ns	2.202	Hi statistics on peak
  128	1445	14.5ns	2.202	Hi statistics run - RF problems interrupt. Feedback needed tweaking
  129	1445	14.5ns	2.202	Hi statistics run
  130	1445	14.5ns	2.002	Corrector scan
  131	1445	14.5ns	2.202	Corrector scan
  132	1445	14.5ns	2.402	Corrector scan

• Pulse #2

  File	KTRIG0	Delay	HTAXU2	Comment
  133	1444	14.5ns	2.202	Burst scan - Possible RF problems
  134	1444	15.0ns	2.202	Burst scan - RF?
  135	1444	14.0ns	2.202	Burst scan
  136	1444	15.5ns	2.202	Burst scan
  137	1444	14.5ns	2.202	Burst scan - RF problems
  138	1444	15.25ns	2.202	Burst scan
  139	1444	15.25ns	2.202	Hi statistics run
  140	1444	14.5ns	2.202	Burst scan (unstable RF plot)
  141	1444	15.25ns	2.202	Burst scan
  142	1444	14.75ns	2.202	Burst scan
  143	1444	15.75ns	2.202	Burst scan

• Pulse #3

  File	KTRIG0	Delay	HTAXU2	Comment
  144	1443	15.0ns	2.202	Burst scan
  145	1443	14.5ns	2.202	Burst scan
  146	1443	14.0ns	2.202	Burst scan
  147	1443	15.5ns	2.202	Burst scan (RF glitch plot)
  148	1443	16.0ns	2.202	Burst scan
  149	1443	15.0ns	2.202	Burst scan - high statistics
  150	1443	15.25ns	2.202	Burst scan - high statistics
  151	1443	14.75ns	2.202	Burst scan - high statistics
  152	1443	14.5ns	2.202	Burst scan

• Stop to readjust LLRF and feedback
• Re-check Pulse #3 and continue to pulse #1000

  File	KTRIG0	Delay	HTAXU2	Comment
  153	1443	15.0ns	2.202	Burst scan
  154	445	15.0ns	2.202	Burst scan
  155	445	15.5ns	2.202	Burst scan
  156	445	16.0ns	2.202	Burst scan - still seeing signs of RF feedback problems (plot)
  157	445	14.5ns	2.202	Burst scan
  158	445	15.25ns	2.202	Burst scan - high statistics (still signs of RF FB problems - plot)
  159	445	15.0ns	2.202	Burst scan - high statistics
  160	445	15.5ns	2.202	Burst scan - high statistics

• Go to pulse #100

  File	KTRIG0	Delay	HTAXU2	Comment
  161	1345	15.0ns	2.202	Burst scan
  162	1345	15.5ns	2.202	Burst scan
  163	1345	16.0ns	2.202	Burst scan
  164	1345	14.5ns	2.202	Burst scan
  165	1345	15.0ns	2.202	Burst scan - high statistics
  166	1345	15.25ns	2.202	Burst scan - high statistics
  167	1345	14.75ns	2.202	Burst scan - high statistics

• Straight Through Beam - Final check

  File	KTRIG0	Delay	HTAXU2	Comment
  168	1446	15.0ns	0.500	Garbage
  169	1446	15.0ns	0.000	Burst scan - high statistics

• DONE

Friday 26 May

• 18:00 Have received a few more hours of beam time thanks to Ray Fliller and Helen Edwards to make a final scan of the primary pulse from the FID pulser
• Files 170-173 were tune up files
  • Adjust Q2AX14 and Q3AX14 quads to optimize beam through kicker
  • Adjust HTAX12 to adjust position in kicker so that we don't scrape with a full kick while still having good throughput with no kick.
• Encounter more RF feedback problems and Ray decides to reboot the LLRF control computer
  • Unable to make the RF feedback stable.
  • The problems are found to be unrelated to beam in the cavity.
  • Giving up for today.

Saturday 27 May

The present intention is to leave the FID pulser at FNAL for at least a few weeks and try some remote testing. This will be more efficient for the long term if we can make it work.

Take advantage of a couple free hours before today's flight to take some scope data with the +/-1kV FID pulser. The present triggering configuration and signal configuration are as follows:

• Triggering
  • 1 MHz A0 trigger signal is the input through an RG58 delay cable (of order 100 ns???) followed by a cable-based delay box with 32+128 ns of delay setting
  • The output of the delay box goes through a 4ns RG58 cable to a Stanford Research Systems Model DG535 digital delay/pulse generator
  • DG535 output is fed through an 8ns RG58 cable to a Phillips PM5781 programmable pulse generator (125 MHz) and from there to the FID pulser via a (~6ns) cable RG58 cable
• Signal
  • Heliax (1/2") cable from the output of the FID pulser to the stripline kicker
  • 44 ns of RG213 cable from stripline output to attenuator stages (34dB JFW 50FH-034-5 power atten followed by TexScan FP-50 6dB atten)
  • After the attenuators, 16ns of RG58 cable takes the signal to another TexScan FP-50 6dB attenuator on the front of the scope
  • Scope is triggered off of the Sync Out signal from the FID pulser
• All traces taken with a LeCroy LC574AL 1 GHz Oscilloscope

Scope traces taken after the output of the FID +/-1kV pulser:

• 12:16 First pulse (239.1 ns trace delay).

   D003.TIF 

• 12:30 First pulse with signs of occasional 0.25 ns glitches.

   D004.TIF 

• 12:34 Second pulse (1.2357 microsec trace delay) showing signs of +/- 0.25 ns jitter.

   D005.TIF 

• 12:38 Third pulse (2.2320 microsec trace delay).

   D006.TIF 

• 12:40 Fourth pulse (3.2291 microsec trace delay).

   D007.TIF 

• 12:42 Fifth pulse (4.2259 microsed trace delay).

   D008.TIF 

• First 10 pulses in train in accumulation mode.

   D009.TIF 

• First 6 pulses with shifted trigger to show that we are sampling at start of train.

   D010.TIF 

• 10 pulses with 99.7 microsecond delay to show approx. pulse 100 in train.

   D011.TIF 

• 12:53 10 pulses with 0.9999 ms delay to show approx. pulse 1000 in train.

   D012.TIF 

• 12:58 Tenth pulse (9.2109 microsec trace delay).

   D013.TIF 

Switch to internal triggering of the pulser. Trigger off first positive pulse in burst. Scope traces:

• 13:14 First pulse.

   D014.TIF 

• 13:16 Second pulse (339.3 ns trace delay).

   D015.TIF 

• 13:19 Third pulse (681.4 ns trace delay).

   D016.TIF 

• 13:21 Fourth pulse (1.0025 ns trace delay).

   D017.TIF 

• 13:25 Fifth pulse (1.3638 ns trace delay).

   D018.TIF 

• 13:29 10th pulse (3.0714 ns trace delay).

   D019.TIF 

• 13:33 30th pulse (9.9016 ns trace delay).

   D020.TIF 

• 13:41 First 6 pulses with 0.2 microsec/division.

   D021.TIF 

Desired future scan

• Fast scan over primary peak (approx. 150 shots per point)

  File	KTRIG0	Delay	HTAXU2	Comment
  174	1445	3.5ns	0.000
  175	1445	8.5ns	0.000
  176	1445	9.5ns	0.000
  177	1445	10.5ns	0.000
  178	1445	11.5ns	0.600
  179	1445	12.5ns	1.800
  180	1445	13.0ns	3.000
  181	1445	13.5ns	3.600
  182	1445	13.8ns	4.000
  183	1445	14.0ns	4.200
  184	1445	14.2 ns	4.200
  185	1445	14.4 ns	4.200
  186	1445	14.6 ns	4.200
  187	1445	14.8 ns	4.200
  188	1445	15.0 ns	4.200
  189	1445	15.2 ns	4.200
  190	1445	15.5 ns	4.000
  191	1445	16.0 ns	3.600
  192	1445	16.5 ns	3.000
  193	1445	17.5 ns	1.800
  194	1445	18.5 ns	0.600
  195	1445	19.5 ns	0.000
  196	1445	20.5 ns	0.000
  197	1445	25.5 ns	0.000