Transcript Conventional Source for ILC - International Linear Collider

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 2014
KEK, Junji Urakawa
Contents :
1. Short review of conventional positron source for ILC
2. 300Hz Linac Scheme for Beam Loading Compensation
using TW.
3. Plan for beam loading compensation experiment at ATF
4. Preparation status
5. 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 beam
0<t<264.45ns, i=0.532A
264.45<t<362.85ns, 0A
362.85ns<t<627.3ns, 0.532A
627.3ns<t<725.7ns, 0A
725.7ns<t<990.15ns, 0.532A
0.532A is beam loading current.
Bunch by bunch
extraction from
Damping Ring
to make ILC beam
train.
This is the model for
positron target system
to confirm the generation
of ILC positron beam.
2. 300Hz Linac Scheme for Beam Loading Compensation
Phase to Amplitude Modulation Method
for Beam Loading Compensation
300Hz Power
Supply
Low Level RF
Phase Shifter
and Amp.
80MW Klystron
3dB High Power
RF Combiner
50W High Power
Terminator
MV
3x1010
60
positron/bunch
300Hz triplet beam
Less than +/- 0.7%
Beam loading current
0.78A.
50
40
30
300Hz Power
Supply
20
10
80MW Klystron
500
1000
1500
2000
2500
ns
We need the precise control of
the phase shifters.
Low Level RF
Phase Shifter
and Amp.
3dB High Power
RF Combiner
50W High Power
Terminator
3m long constant gradient travelling wave structure
Also, I assume 10% margin as wave guide loss and so on because of
the experience at ATF Linac. So, klystron output power 80MW and
3ms pulse width are necessary.
Control of input RF power by phase shifters
Detail of beam loading
compensation:
Less than ±0.7% is possible
For ILC 300Hz multi-bunch
beam.
Y [MW]
データ 2
70
60
MV
64
50
63
40
500
1000
1500
2000
2500
ns
30
20
-500
0
500
X [ns]
1000
1500
2000
300ns
53.2ns
53.2ns
53.2ns
12.5Hz Power
Supply
80MW Klystron
Low Level RF
Phase Shifter
and Amp.
3dB High Power
RF Combiner
50W High Power
Terminator
3m long constant gradient travelling wave structure
Essential Beam Loading
Compensation Scheme
for proof-principle
experiment at ATF in this
September
3m long constant gradient travelling wave structure
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 train
12.5Hz Amp.
4th higher
harmonics
generator
(crystal:BBO)
3. Plan for beam loading compensation experiment at ATF
Extraction line
Damping Ring
Photo-cathode RF gun
(electron source)
S-band Linac
1.4x1010 electrons/bunch
with 2.8nsec bunch spacing
and 2856MHz Linac
beam loading current: 0.78A
MV
70
60
50
40
12.5Hz Power
Supply
30
20
80MW Klystron
10
500
Low Level RF
Phase Shifter
and Amp.
3dB High Power
RF Combiner
1000
1500
2000
2500
ns
We need the precise control of
the low level phase shifters.
50W High Power
Terminator
3m long constant gradient travelling wave structure
Also, I assume 10% margin as wave guide loss and so on because of
the experience at ATF Linac. So, klystron output power 80MW and
3ms pulse width are necessary.
ATF Injector for 1.3 GeV ATF Linac will be modified for beam
loading compensation experiment in this summer.
3m long TW
3.6 cell RF Gun
3m long TW
45 degrees bending magnet
to measure the energy of multi-bunch
Beam Transport
3x1010 with 6.15nsec bunch spacing corresponds to 1.4x1010
in the case of 2.8nsec bunch spacing with same beam loading
in multi-bunch trains.
ATF Triplet Beam : 3x20 bunches/train with 60nsec train gap
and 2.8nsec bunch spacing. This operation is possible in the
safety of the radiation for ATF accelerator. However, since I
want to make more safety margin, following doublet beam
scheme is proposed.
166.4ns
53.2ns
53.2ns
~60.0ns
80MW, 4.5ms
12.5Hz Power
Supply
80MW Klystron
Low Level RF
Phase Shifter
and Amp.
3dB High Power
RF Combiner
Essential Beam Loading
Compensation Scheme
for proof-of-principle
experiment at ATF
50W High Power
Terminator
3m long constant gradient travelling wave structure
3m long constant gradient travelling wave structure
12.5Hz Power
Supply
80MW, 3ms
40MW, 1.5ms
Amplitude
Modulation
12.5Hz Power
Supply
Low Level RF
Phase Shifter
and Amp.
60MW Klystron
3dB High Power
RF Combiner
50W High Power
Terminator
fast phase control
Generation of three
45 degrees bending magnet
mini-train per pulse
to measure the energy of multi-bunch
3.6 cell RF Gun SW
3m long TW
3m long TW
Chicane
150 bunches/pulse with 2.8ns bunch spacing 23.4
Momentum [MeV/c]
Intensity [V]
0
-0.1
-0.2
-0.3
-100
2nC/bunch
0
100
200 300 400
Time [ns]
23.3
23.2
23.1
Energy spread 0.1% in rms
23
500
600
0
50
100
Bunch Number
150
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 train
Delay line
12.5Hz Amp.
4th higher
harmonics
generator
(crystal:BBO)
Present laser system,
Two Pockels cells,
1.6 cell RF Gun, Chicane
and BPM were used
to generate doublet
pulse train and to measure
energy of each bunch.
0.78 x1010 electrons per
bunch.
Waveguide system should be changed to match the beam loading experiment after
summer shutdown of ATF operation. Following plan was proposed and necessary components
were ordered. We want to start the change of the waveguide system from mid. of July and will
complete it by mid. of August.
Present waveguide for KLY#0
Present waveguide for KLY#1
Present waveguide for KLY#2
Present waveguide system
KLY#0
KLY#1
KLY#2
New waveguide system for beam loading compensation experiment
To L0
To Gun
KLY#2
KLY#1
Generation of two
mini-train per pulse L0
3.6 cell RF Gun SW
3m long TW
Chicane
KLY#0
45 degrees bending magnet
to measure the energy of multi-bunch
3m long TW
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 system
by mid. of August. Then, we will start the RF aging and test new instrumentation from
end of August.
I-Q modulation & detection
Function Generator
5. Summary
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.
3m long TW
3.6 cell RF Gun
3m long TW
45 degrees bending magnet
to measure the energy of multi-bunch
Beam Transport
2x1010 with 6.15nsec bunch spacing corresponds to 0.9x1010
in the case of 2.8nsec bunch spacing with same beam loading
in multi-bunch trains.
3x1010 with 6.15nsec bunch spacing corresponds to 1.4x1010
in the case of 2.8nsec bunch spacing with same beam loading
in multi-bunch trains.
40MW, 1.5ms
12.5Hz Power
Supply
Amplitude
modulation
80MW, 3ms
12.5Hz Power
Supply
Low Level RF
Phase Shifter
and Amp.
60MW Klystron
3dB High Power
RF Combiner
50W High Power
Terminator
Generation of three
45 degrees bending magnet
mini-train per pulse
to measure the energy of multi-bunch
3.6 cell RF Gun SW
3m long TW
3m long TW
Chicane
150 bunches/pulse with 2.8ns bunch spacing 23.4
Momentum [MeV/c]
Intensity [V]
0
-0.1
-0.2
-0.3
-100
1nC/bunch
0
100
200 300 400
Time [ns]
23.3
23.2
23.1
Energy spread 0.1% in rms
23
500
600
0
50
100
Bunch Number
150