Download Adolphsen_BAW2_SLAC_01_20_11

KCS and RDR 10 Hz
Operation
Chris Adolphsen
BAW2, SLAC
1/20/2011
Assumptions
At lower gradients, reduce modulator voltage and increase pulse
rate so nominal average modulator input power not exceeded
- thus the charging power supplies would see the same or
smaller load (which is roughly constant), and the AC power
capacity would not have to be increased.
Modulator
Cell Voltage
Same Slope
5 Hz
10 Hz
Discharge Level Differs
Every Other Pulse
Time
Additional line ripple introduced by alternating discharge levels would
need to be reduced in the site electrical distribution system.
SLAC/KEK Toshiba 10 MW MBK
Efficiency and Output Power
Versus Beam Voltage
Cases Considered
• 250 GeV, 5 Hz
– Modulator Voltage = 117 kV, Klystron Power = 10 MW, Kly Eff = 68%
• 150 GeV, 5 Hz
– Cavity QL = (150/250) times that at 250 GeV – fill time shortened by the
same factor
– Modulator Voltage = 99.5 kV, Klystron Power = 6 MW, Kly Eff = 60%
• 125 GeV, 5 Hz
– Assume same QL as for 150 GeV (cannot switch between pulses)
– Required rf power = 6 MW * ¼ * (1 + 125/150)^2 = 5.04 MW, just slightly
more as if QL were optimized for 125 GeV
– Reflected power during beam = 6 MW * ¼ * (1 - 125/150)^2 = .04 MW
– Also the fill time is (150/125)*log(1 + 125/150)/log(2) = 1.05 times longer
than if QL were optimized for 125 GeV
– Modulator Voltage = same as 150 GeV case (although may be able to run
at a lower modulator voltage every other pulse). To lower the RF power for
KCS, reduce number of ‘on’ klystrons by 1 – (5.04/6)^0.5 = 8%, while for the
RDR case, reduce the rf drive power.
Results
10 Hz
Summary
• The half current case clearly exceeds the RDR average
modulator input power limit when running at 150 GeV (5 Hz) +
125 GeV (5 Hz), but this added capacity is needed anyway run
at 250 GeV (5 Hz) with half current.
• The full current case is marginal at 10 Hz although if can
alternate the modulator voltages, only 4% more AC power would
be required.
• The half bunches, same rf pulse case for 150 GeV (5 Hz) + 125
GeV (5 Hz) would work and does not require any increased
capacity (AC, cooling or cryo)
Klystron Cluster Scheme Tests
Resonantly power a 0.5 m diameter, pressurized (1 atm N2), 10 m long
aluminum pipe to 300 MW TE01 mode field equivalent in 1 ms pulses
550 KW input power yields
300 MW equivalent surface
fields in the pipe - see bkd
every ~ 15 hours, maybe
from CTO or upstream –
rate seems very pressure
dependent
Power to CTO (kW)
‘Big Pipe’ Operation
600
400
200
0
0
10
20
30
40
50
Time: Hrs
60
70
80
60
70
80
75
CTO 1
dBm
Acoustic Sensor
Breakdown Localization
74
73
2
72
71
70
0
Time of Position 2 markers (T1,T2)
are ~ 1 ms later than those from
Position 1, which suggest events are
much closer to Position 1 (5 m / 5100
m/s ~ 1 ms)
10
20
30
T1 T2
40
50
Time: Hrs
Next: 160 m Resonate Ring