Demonstration of the Beam loading compensation (Preparation status for ILC beam loading compensation experiments at ATF injector in this September) (PoP experiment on beam loading for truly conventional positron source at ATF injector ) AWLC14 at FNAL, 12-16 M KEK, Junji ontents : . Short review of conventional positron source for . 300Hz Linac Scheme for Beam Loading Compensation sing TW. . Plan for beam loading compensation experiment at . Preparation status . Summary
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Demonstration of the Beam loading compensation (Preparation status for ILC beam loading compensation experiments at ATF injector in this September) (PoP.
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Demonstration of the Beam loading compensation
(Preparation status for ILC beam loading compensation experiments at ATF injector in this September)
(PoP experiment on beam loading for truly conventional positron source at ATF injector )
AWLC14 at FNAL, 12-16 May 2014KEK, Junji Urakawa
Contents : 1. Short review of conventional positron source for ILC2. 300Hz Linac Scheme for Beam Loading Compensation using TW.3. Plan for beam loading compensation experiment at ATF4. Preparation status5. Summary
1. Short review of conventional positron source for ILC
A conventional positron source for international linear collider,NIM A Volume 672, 21 April 2012, Pages 52-56
Time structure of beam0<t<264.45ns, i=0.532A264.45<t<362.85ns, 0A362.85ns<t<627.3ns, 0.532A627.3ns<t<725.7ns, 0A725.7ns<t<990.15ns, 0.532A0.532A is beam loading current.
Bunch by bunch extraction fromDamping Ringto make ILC beamtrain.
This is the model for positron target systemto confirm the generationof ILC positron beam.
Phase to Amplitude Modulation Method for Beam Loading Compensation
300Hz Power Supply
Low Level RFPhase Shifterand Amp.
3dB High PowerRF Combiner
50W High PowerTerminator
80MW Klystron
2. 300Hz Linac Scheme for Beam Loading Compensation
500 1000 1500 2000 2500ns
10
20
30
40
50
60
MV
300Hz Power Supply
Low Level RFPhase Shifterand Amp.
3dB High PowerRF Combiner 50W High Power
Terminator
80MW Klystron
3m long constant gradient travelling wave structure
We need the precise control ofthe phase shifters.
Also, I assume 10% margin as wave guide loss and so on because of the experience at ATF Linac. So, klystron output power 80MW and3ms pulse width are necessary.
3x1010 positron/bunch300Hz triplet beamLess than +/- 0.7%Beam loading current0.78A.
500 1000 1500 2000 2500ns
63
64MV
20
30
40
50
60
70
- 500 0 500 1000 1500 2000
2データ
Y [MW]
X [ns]
Detail of beam loading compensation:Less than ±0.7% is possibleFor ILC 300Hz multi-bunchbeam.
Control of input RF power by phase shifters
12.5Hz Power Supply
Low Level RFPhase Shifterand Amp.
3dB High PowerRF Combiner 50W High Power
Terminator
80MW Klystron
3m long constant gradient travelling wave structure3m long constant gradient travelling wave structure
Essential Beam Loading Compensation Schemefor proof-principle experiment at ATF in thisSeptember
300ns53.2ns 53.2ns 53.2ns
ATF laser system for photo-cathode RF Gun can generate triplet laser beam of 20 pulse with 2.8ns bunch spacing and about 100ns gap by minor modifications.
357MHz Laser oscillator
Pockels cell to make triplet laser
pulse train12.5Hz Amp.
4th higher harmonics generator
(crystal:BBO)
Photo-cathode RF gun(electron source)
S-band Linac
Extraction line
Damping Ring
3. Plan for beam loading compensation experiment at ATF
12.5Hz Power Supply
Low Level RFPhase Shifterand Amp.
3dB High PowerRF Combiner 50W High Power
Terminator
80MW Klystron
3m long constant gradient travelling wave structure
We need the precise control ofthe low level phase shifters.
Also, I assume 10% margin as wave guide loss and so on because of the experience at ATF Linac. So, klystron output power 80MW and3ms pulse width are necessary.
500 1000 1500 2000 2500ns
10
20
30
40
50
60
70MV1.4x1010 electrons/bunch
with 2.8nsec bunch spacingand 2856MHz Linacbeam loading current: 0.78A
3.6 cell RF Gun
3m long TW 3m long TW
3x1010 with 6.15nsec bunch spacing corresponds to 1.4x1010 in the case of 2.8nsec bunch spacing with same beam loadingin multi-bunch trains.ATF Triplet Beam : 3x20 bunches/train with 60nsec train gapand 2.8nsec bunch spacing. This operation is possible in thesafety of the radiation for ATF accelerator. However, since I want to make more safety margin, following doublet beamscheme is proposed.
45 degrees bending magnetto measure the energy of multi-bunch
Beam Transport
ATF Injector for 1.3 GeV ATF Linac will be modified for beam loading compensation experiment in this summer.
80MW, 4.5ms12.5Hz Power Supply
Low Level RFPhase Shifterand Amp.
3dB High PowerRF Combiner 50W High Power
Terminator
80MW Klystron
3m long constant gradient travelling wave structure3m long constant gradient travelling wave structure
Essential Beam Loading Compensation Schemefor proof-of-principle experiment at ATF
166.4ns53.2ns 53.2ns
~60.0ns
3.6 cell RF Gun SW 3m long TW 3m long TW
45 degrees bending magnetto measure the energy of multi-bunch
12.5Hz Power Supply
Low Level RFPhase Shifterand Amp.
3dB High PowerRF Combiner
50W High PowerTerminator
60MW Klystron
fast phase control
23
23.1
23.2
23.3
23.4
0 50 100 150
Mo
men
tum
[M
eV/c
]
Bunch Number
-0.3
-0.2
-0.1
0
-100 0 100 200 300 400 500 600
Inte
nsi
ty [
V]
Time [ns]
Energy spread 0.1% in rms
150 bunches/pulse with 2.8ns bunch spacing
Generation of threemini-train per pulse
12.5Hz Power Supply
2nC/bunch
Chicane
AmplitudeModulation
40MW, 1.5ms 80MW, 3ms
ATF laser system for photo-cathode RF Gun can generate doublet laser beam of 20 pulse with 2.8ns bunch spacing and about 100ns gap by two Pockels cells.
357MHz Laser oscillator
Pockels cell to make doublet
laser pulse train12.5Hz Amp.
4th higher harmonics generator
(crystal:BBO)Delay line
Present laser system,Two Pockels cells,1.6 cell RF Gun, Chicaneand BPM were usedto generate doublet pulse train and to measureenergy of each bunch.0.78 x1010 electrons perbunch.
Waveguide system should be changed to match the beam loading experiment after summer shutdown of ATF operation. Following plan was proposed and necessary componentswere ordered. We want to start the change of the waveguide system from mid. of July and willcomplete it by mid. of August.
Present waveguide for KLY#0Present waveguide for KLY#1
Present waveguide for KLY#2
KLY#0KLY#1KLY#2
KLY#0KLY#1KLY#2
Present waveguide system
New waveguide system for beam loading compensation experiment
To GunTo L0
3.6 cell RF Gun SWL03m long TW 3m long TW
45 degrees bending magnetto measure the energy of multi-bunch
Generation of twomini-train per pulse
Chicane
Several modules and function generators were ordered for the control of RF phase and amplitude which are necessary for the beam loading compensation experiment. We will install necessary control devices and monitor systemby mid. of August. Then, we will start the RF aging and test new instrumentation from end of August.
Function Generator
I-Q modulation & detection
3.6 cell RF Gun
3m long TW 3m long TW
2x1010 with 6.15nsec bunch spacing corresponds to 0.9x1010 in the case of 2.8nsec bunch spacing with same beam loadingin multi-bunch trains.
3x1010 with 6.15nsec bunch spacing corresponds to 1.4x1010 in the case of 2.8nsec bunch spacing with same beam loadingin multi-bunch trains.
45 degrees bending magnetto measure the energy of multi-bunch
Beam Transport
Injector for 1.3GeV ATF Linac will be modified for beam loading compensation experiment in this summer.Due to the lack of 2013 budget, we delayed this experiment, sorry.
5. Summary
3.6 cell RF Gun SW 3m long TW 3m long TW
45 degrees bending magnetto measure the energy of multi-bunch