1. Pulsed Ion Linac for EIC
January 27, 2010
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2. Content
Pulsed linac
Short Normal Conducting section: RFQ and IH structure
Stripper for heavy ions at 12 MeV/u

3. Basic parameters of the linac
Linac layout
Ion Sources
RFQ IH QWR
QWR
HWR
DSR
MEBT Stripper
Normal conducting
Superconducting

4. Radio Frequency Quadrupole
A Segment of the RFQ
Basic RFQ Parameters
Frequency
115 MHz
Total length
3.6 m
Voltage
85 kV
Average radius
7 mm
Number of segments 4
Input energy
25 KeV
Output energy
500 keV/u

5. Example of a short MEBT Q1 Buncher Q2 Q3 Q4 L= 995 mm
Basic Quadrupoles
Parameters
Basic Buncher
Parameters
Eff. Length (mm)
Gradient (T/m) Q1
20.0
23.0 Q2
50.0
-22.0 Q3
32.75 Q4
-16.5
Cavity
Quarter Wave
Voltage
0.8 MV
Frequency
117.3 MHz
Length
340 mm

6. Normal Conducting IH cavities
TRIUMF Separated DTL
Courtesy Bob Laxdal

7. Normal Conducting IH structure
U. Ratzinger (Frankfurt) Group has built it for the BNL EBIS injector project

8. Stripping energy
Lead ions

9. Superconducting cavities
QWR HWR DSR
119 cavities
21 cryostats

10. Voltage gain per cavity for lead ions

11. Voltage gain per cavity for protons

12. Energies of different ion beams

13. Accelerated Beam Parameters
Transverse normalized emittance (5rms) ~ 1  mmmrad
Longitudinal emittance (5rms) <10  keV/unsec
Momentum spread can be controlled by the rebuncher and can be as low as ~0.05%.

14. Proton Beam Linac Pulse Length (s) = 2.50E-04 Frequency (MHz) = 115
Number of Bunches in Pulse=
28750
Average current per pulse, P (A)=
2.00E-03
Charge per pulse (C)=
5.00E-07
Number of protons per pulse =
3.13E+12
Injection Efficiency=
0.9
Transverse cooling time (s) =
0.130
Longitudinal cooling time (s) =
0.067
RF acceleration time (s) =
0.080
Injection
Extraction
Cycle Time(s)
Ion A Q
I (A)
S (m)
MeV/n γ β
N_total
Pulses P 1
300
200
1.21
0.57
1.10E+13
3000
4.22
0.97
6.43E+12 4
0.70
250
9.17E+12
5.36E+12 3
0.61
7.34E+12
4.29E+12
0.52
150
5.50E+12
3.22E+12 2
0.43

15. Lead Beam Linac Pulse Length (s) = 2.50E-04 Frequency (MHz) = 115
Number of Bunches in Pulse=
28750
Average current per pulse, Pb (A)=
5.00E-04
Charge per pulse (C)=
1.25E-07
Average charge state of lead ion= 67
Number of lead ions per pulse =
1.17E+10
Injection Efficiency=
0.5
Transverse cooling time (s) =
0.130
Longitudinal cooling time (s) =
0.067
RF acceleration time (s) =
0.080
Injection
Extraction
Cycle Time(s)
Ion A Q
I (A)
S (m)
MeV/n γ β
N_total
Pulses Pb
207 1
300 70
1.08
0.37
2.54E+11
1180
2.27
0.90
1.04E+11 18
2.48
250
2.12E+11
8.66E+10 15
2.10
200
1.69E+11
6.93E+10 12
1.71
150
1.27E+11
5.20E+10 9
1.32

16. Spin tracking in the LINAC (first segment of the linac)
Linac with solenoids
Linac with doublets
Initial Polarization
Direction
Final Polarization in Linac with Solenoids
(Direction of polarization changes)
Final Polarization in Linac with Doublets
(Direction remains same as initial)
Emittance
5*Emittance
(%)
Spread X 99
3x10-2 98
2x10-1
1x10-2
5x10-2 Y
3 x10-2 Z
4x10-2 96
3x10-1
7x10-2

17. QWR and HWR production at ANL
QWR, f=109 MHz, = HWR, f=172 MHz, =0.26

18. Advanced EM Optimization of New Cavities
Advanced EM optimization : outer conductor:
form cylinder to conical shape
Drift tubes are highly optimized to reduce EPEAK
2.5 deg drift tube face tilt to compensate beam
steering effect
109 MHz
Frequency
72.75
MHz
beta
0.14
0.077
U0 at 1 MV/m
0.4
0.39 J bl 39 32 cm
EPEAK at 1 MV/m
5.0
4.6
MV/m
BPEAK at 1 MV/m 92 76 Gs G 40 26
Ohm
Rsh/Q
548
575
Voltage per cavity
2.1
2.5 MV
Dynamic LHe load 6
11.4 W
72.75 MHz

19. Cryomodule assembly at ANL
beam

20. Cavity subsystems Piezoelectric tuner (PZT) 4 kW capacitive coupler
~90 Hz window
35 m displacement
4 kW capacitive coupler
Adjustable
1 cold and 1 warm windows
Pneumatic slow tuner
beam
PZT has been tested with
excellent performance
RF Coupler

21. Recently developed and built QWR, 72.75 MHz

22. Remaining tasks for the linac pre-conceptual design
Status of the injectors
2 mA is available for polarized light ion beams
2 mA is not available yet for lead ions
~0.5 mA is realistic number
Can be increased by using 56 GHz ECRs –expensive device
Update the linac design on the base of recent (3-4 years) progress in performance of TEM class cavities
Introduce better optimization of EM parameters to reduce Epeak/Eacc and Bpeak/Eacc
Peak magnetic field can be as high as ~90 mT for the pulsed operation
Peak electric field ~40 MV/m
Optimal injection energy to the pre-booster
Do we need 100 MeV/u lead ions and 280 MeV H-minus?
Focusing system
In SC environment, focusing by SC solenoids is cost effective
Spin dynamics studies to avoid depolarization effects: compare quadrupole and solenoid focusing