RF Structures

J. Alessi

Some general thoughts on what our approach will be.

4 m 4.3 m

RFQ: 17 - 300 keV/u; 100 MHz

IH Linac: 0.3 - 2.0 MeV/u; 100 MHz

Proposed Linac –Based RHIC Preinjector

LEBTMEBTHEBT

Ion U – D

q/m .16-0.5

Current 1.5 emA (for 1 turn inj)

Pulse Length

Rep. Rate

Duty Factor

10 s

5 Hz

0.005 %

Emittance 0.7 mm rad (nor, 90%)

Energy Spread

1.8 keV/amu

RFQ:

100 MHz, 4 rod design is conventional. Very similar to GSI, CERN, etc.

Deepak’s talk – injection energy chosen to reduce space charge problems in LEBT.

Will probably buy RFQ from Frankfurt.

LINAC:

IH structure chosen, very similar to CERN Pb linac. (conventional baseline design).

Will probably get IH from GSI / Frankfurt.

SCL was considered, but abandoned for since it is not required to meet design requirements, it has higher cost, and the technology is less familiar in Collider-Accelerator, so would increase operational burden. We have left space after the linac for the possibility of future superconducting post-accelerator.

Bunchers – MEBT, 2 in HEBT (Frankfurt?)

Parameters BNL CERN Units

Type 4-rod 4-rod

Q/m 0.16-0.5 0.12

Input Energy 16.2 2.5 keV/amu

Output Energy 314.72 250 keV/amu

Frequency 101.28 101.28 MHz

Max rep rate 10 10 Hz

Length 4.37 2.5 meters

Number of cells 277

Aperture Radius 0.005 .0045 meters

Voltage 69 70 kV

E(surface) 20.8 23 MV/m

RF Power < 350 < 350 kW

Acceptance 1.7 > 0.8 mm mrad (nor)

Input Emittance 0.35 mm mrad, nor, 90%

Output Emittance (trans)

0.375 mm mrad, nor, 90%

Output Emittance (longit)

33.6 MeV deg, 90%

Transmission 91 93 %

Bravery factor 1.8 2 Kilpatrick

RFQ

Parameters BNL CERN Tank 1

Units

Q/m 0.16-0.5 0.12

Input energy 0.314 0.250 MeV/amu

Output Energy 2.08 1.87 MeV/amu

Frequency 101.28 101.28 MHz

Max rep rate 5 10 Hz

Length 4.0 3.57 Meters

Input emittance 0.55 mm mrad, norm, 90%

Output emittance 0.61 mm mrad, norm, 90%

Output energy spread 20.0 keV/amu

Transmission 100 %

Two quadrupole triplets inside for focusing. The maximum field on the axis will be 13.5 MV/m. Fixed output velocity, independent of the q/m of the desired beam (cavity gradient is adjusted for different q/m's, to maintain a fixed velocity profile).

IH Linac

Munich

Similar Linacs:

REX-Isolde

1

20

10

40

60

80

100

150

200

Beam Velocity ( β ％ )2 4 86 10 15

27MHz Wideroe

RFQ

54MHzAlvalez

108MHz Alvalez

S

hu

nt

Imp

ed

an

ce M

Ω/m

48MHz TITech-IH

100MHz TITech-IHQ

96MHz TITech-IH

103 MHz TITech &TUM-IH

IH structure

・ RF type LINAC・ TE mode・ High Shunt-Impedance

cavity

drift-tubes

ridge

RIKEN - Okamura

RIKEN - Okamura

RIKEN - Okamura

A simple study for AGS 1. Initial condition

• Energy_input :300keV/u

• Energy_output :2MeV/u

• Frequency :101.28MHz

• Particles :Au30+

• ΔEnergy_output:1%

• Accelerate ratio :5MeV/m

• Phase pattern :-30,-30, ・・・ (.not. APF)

RIKEN - Okamura

A simple study for AGS2.Number of cell

　 In ⇒(Avg.) OUT

Energy 300keV/u1150keV/

u 2MeV/u

β 0.0252 0.0494 0.0653

Βλ/2 37.44 73.26 96.54Accelerate ratio : 5MeV/mTotal length : ≒ 3m3000 / 73.27 ≒ 41 cell

RIKEN - Okamura

A simple study for AGSSummary

• Eff. Shunt impedance:110MΩ/m• RF power :375kW• Total length :3 m• Focusing :APF , PM or EM

• Field simulation is very important.

• Cost :$300k ?

RIKEN - Okamura

While the combination of EBIS, RFQ, and room temperature IH linac will meet both RHIC and NSRL requirements, there would be some advantage for lower mass beams if a superconducting linac were built rather than the IH linac.

A SC linac, with independently phased accelerating cavities, would allow one to inject these lower mass beams into the Booster at higher energies, avoiding the need for bunch merging in the Booster.

The SC option was left out of the baseline design, since it is somewhat more costly (preliminary estimate is an increase of several M$ in the cost). In addition, the technology is less familiar in Collider-Accelerator, so would increase operational burden. We have left room for a superconducting post-accelerator (future upgrade).

SCL Option

Parameter Values UnitsQ/m 0.16-1.0  

Input energy 0.300 MeV/amuOutput Energy 2-7.5 MeV/amuFrequency 101.28 MHzMax rep rate 5 HzInput emittance 0.55 mm mrad, norm,90%

Output emittance ~ 0.6 mm mrad, norm,90%

Transmission 100 %

-Accelerating Gradient 7MV/m-Energy gain 5MeV/charge/cryostat-Three cryostats to produce 15 MeV for the SCL

-Allows acceleration to higher energies for higher q/m ions (> 6MeV/u for q/m=0.5) -Based on ATLAS, ALPI, ISAC-II and RIA technology-Two type of cavity ~0.04(14) and 0.08 (10)

The ALPI resonator

SCL Parameters

Parameter Values Units

Q/m 0.16-0.67

 

Input energy 0.300 MeV/amu

Output Energy 2-7.5 MeV/amu

Frequency 101.28 MHz

Max rep rate 10 Hz

Input emittance 0.55 mm mrad, norm,90%

Output emittance

~ 0.6 mm mrad, norm,90%

Transmission 100 %

-Accelerating Gradient 7MV/m-Helium Consumption >7 Watt at 4.2K / resonator-Energy gain 5MeV/charge/cryostat-Three cryostats to produce 15 MeV for the SCL

TRACE Simulation for SCL (Au)

4.000 mm X 15.000 mrad

5.000 Deg X 999.00 keV

4.000 mm X 15.000 mrad

5.000 Deg X 999.00 keV NP2= 78

5.00 mm (Horiz) 180.0 Deg (Long.)

5.00 mm (Vert)

NP1= 1

Length= 6308.40mm

1 2 G 3 4 G 5 6

7 SOL

8 9 10 G 11 12 G 13 14 15 G 16 17 G 18 19

20 SOL

21 22 23 G 24 25 G 26 27 28 G 29 30 G 31 32

33 SOL

34 35 36 G 37 38 G 39 40 41 G 42 43 G 44 45

46 SOL

47 48 49 G

50

51 G 52

53 54 G

55

56 G 57 58

59 SOL

60 61 62 G

63

64 G 65

66 67 G

68

69 G 70 71

72 SOL

73 74 75 G

76

77 G 78

H A= 0.0000 B= 0.30000 V A= 0.0000 B= 0.30000

Z A= 0.0000 B= 1.74800E-02

BEAM AT NEL1= 1 H A= 3.23052E-02 B= 0.88380 V A= 3.23052E-02 B= 0.88380

Z A= 0.90204 B= 2.67026E-03

BEAM AT NEL2= 78 I= 1.7mA W= 59.6543 507.8899 MeV

FREQ= 101.28MHz WL=2960.04mm EMITI= 14.000 14.000 43.70 EMITO= 6.368 6.368*********

N1= 1 N2= 78 PRINTOUT VALUES PP PE VALUE 1 2 0.41468 2 2 -33.00000 2 4 45.60000 2 6 0.00000 2 8 0.00000 1 11 3.00000 MATCHING TYPE = 0

CODE: TRACE3D v66L FILE: ebislin8.txt DATE: 02/27/2004 TIME: 14:36:26

CONCLUSIONS

We have “first pass” beam dynamics calculations for the RFQ and IH structures, which verify that both will meet our requirements.

Both are conventional structures, so although we don’t have the detailed design of the structures, they should be straightforward and very similar to devices already in operation in other facilities.

We will begin to work out the details of collaborations for the design and fabrication of these structures, visits to labs, etc.