PS/RF/Note 97-16
16 September 1997
9 September 1997, PSB RF MD report;
Proton bunch splitting from h = 1 to h = 2 with blow-up
Participants: A. Blas (reporter), R. Garoby, S. Hancock
Experiment limitations:
1 GeV maximum energy
(main power supply ready for 1.4 GeV in 3/98 and septa in 3/99)
Target:
h= 1 acceleration bunch splitting at 1 GeV flat top to h = 2 synchronisation blow-up using h = 9 phase modulated signal.
The aimed intensity at 1.4 GeV is 8 E12 protons with a 1.45 [eV.s] longitudinal emittance per bunch, and a bunch length of 169 ns.
Results:
850 E10 particles accelerated with both C02 and C04 at the same level (7.4 kV).
Bunch splitted by decreasing the C02 level to zero.
Beam synchronised with C04 on its own.
Blow-up with C16 at 2 kV phase modulated (6950 Hz / 2.6 kHzpp frequency modulation ( 21o pic) on signal generator) and C04 decreased to 4.6 kV.
Bunch length at extraction = 200 ns .
Longitudinal emittance obtained at extraction 0.9 1 [eV.s]
Figure 1: Beam intensities with C04 and C02 at the same voltage and 180o phase difference
The results of this machine development were obtained using the hardware represented in figure 2.
Glossary:
TBU1: B train (one pulse for each Gauss)
BTI: B Train Interface (gives a dummy 0.1 Gauss train and has a few logical
functions)
DFP: Digital Frequency program (revolution frequency look-up table)
DAU: Digital Arithmetic Unit (multiplies the revolution word by h)
DLP: Digital Loop Processor (sums the digitised analogue input with the rf frequency
word)
DDS: Direct Digital Synthesiser (transforms the digital word in a rf sine-wave)
PLA: Phase Loop Amplifier (phase loop corrector)
SHC: Second Harmonic Corrector
Figure 2: Hardware used for the dual harmonic acceleration, bunch splitting and blow-up of a proton beam.
Figure 3: Beam during bunch splitting without blow-up
Start = Injection + 430 ms (bottom trace)
Scan every 2000 revolutions during 50 ms
Intensity = 130 E 10 ppp (3 turns injected)
Figure 4: Beam after bunch splitting without blow-up
Start = Injection + 466 ms (bottom trace)
Scan every 200 revolutions during 5 ms
Intensity = 130 E 10 ppp (3 turns injected)
Figure 5: Beam during bunch splitting without blow-up
Start = Injection + 430 ms (bottom trace)
Scan every 2000 revolutions during 50 ms
Intensity = 800 E 10 ppp (13 turns injected)
Figure 6: Beam after bunch splitting without blow-up
Start = Injection + 466 ms (bottom trace)
Scan every 200 revolutions during 5 ms
Intensity = 800 E 10 ppp (13 turns injected)
Figure 7: Beam during bunch splitting with blow-up on a 20 ms elongated cycle
Start = Injection + 439 ms (bottom trace)
Scan every 3491 revolutions during 50 ms
Intensity = 800 E 10 ppp (13 turns injected)
Figure 8: Beam after bunch splitting with blow-up on a 20 ms elongated cycle
Start = Injection + 483 ms (bottom trace)
Scan every 491 revolutions during 5 ms
Intensity = 800 E 10 ppp (13 turns injected)
Figure 9: Beam after bunch splitting without C16 (blow-up cavity) on a 20 ms elongated cycle.
Start = Injection + 486 ms
Intensity = 150 E 10 ppp (3 turns injected)
Figure 10: Beam after bunch splitting with C16 but without phase modulation.
Start = Injection + 486 ms
Intensity = 150 E 10 ppp (3 turns injected)
Figure 11: Beam after bunch splitting with C16 modulated (blow up on).
Start = Injection + 486 ms
Intensity = 150 E 10 ppp (3 turns injected)
Figure 12: Beam after bunch splitting with C16 modulated (blow up on).
Start = Injection + 486 ms
Intensity = 800 E 10 ppp (13 turns injected)
Figure 13: Top trace Beam current (4 E 12 /V)
3 other traces: Voltage program of all 3 cavities
Trig = C35 (injection)
Figure 14: Top trace Beam current (4 E 12 /V)
3 other traces: top:C04 Voltage program
middle: C16
bottom: C02
Trig = C482 ( = BX.SLFT = flat top)
Distribution:
PS/RF/LL section
PSB machine supervisors
PSB operation team
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