Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10,...

Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10 , 2004

D. Kayran, I. Ben-Zvi, D.S. Barton, D. Beavis, M. Blaskiewicz, J.M. Brennan A. Burrill, R. Calaga, P. Cameron,X. Chang, R. Connolly, D.M. Gassner, H. Hahn, A. Hershcovitch, H.-C.Hseuh, P. Johnson, J. Kewisch, R. Lambiase, V.N. Litvinenko, W. Meng, G. McIntyre, T.C. Nehring, A. Nicoletti, D. Pate, J. Rank, T. Roser, T. Russo, J. Scaduto, K.S.Smith, T. Srinivasan-Rao, N.W. Williams, K.-C. Wu,

V. Yakimenko, K. Yip, A. Zaltsman, Y. Zhao, Brookhaven National Laboratory, Upton, NY, USA

H.P. Bluem, A. Burger, M. Cole, A. Favale, D. Holmes, J. Rathke, T. Schultheiss, A. Todd,

Advanced Energy Systems, Medford, NY, USA J. Delayen, W. Funk, L. Phillips, J. Preble,

Thomas Jefferson National Accelerator Facility, Newport News, VA, USA

High Current Energy Recovery High Current Energy Recovery

Linac at BNLLinac at BNL


Outline • ERL prototype

– Goals & Parameters

• Step by Step tests– SRF gun, SRF cavity, beam dump– Future steps:

• return loop for ERL - single and double turns• beam stability and feedbacks tests

• ERL modes of operation– CW and test modes for Navy and DoE– Test relevant for the eRHIC concept

• Conclusion


electrons

ions Gun

Linac 1Linac 2

Linac 3

Linac 4Stretcher

Compressor

electrons

ions

ions Beam dump

Linac

EBIS Booster

AGS

RHIC II

Electro

n

coolin

g

http://www.agsrhichome.bnl.gov/eCool/

Electron cooler for RHIC II project


Goals for ERL R&D program at BNLGoals for ERL R&D program at BNL

• Test the key components of the RHIC II electron cooler: – Au-Au luminosity 7x1027 cm-2sec-1, 10- fold boost in p-p luminosity

• Test the key components of the High Current Energy Recovery Linac based solely on SRF technology– 703.75 MHz SRF gun test with 500 mA – high current 5-cell SRF linac test with HOM absorbers

• Single turn - 500 mA • Two turns - 1 A…..

– test the beam current stability criteria for CW beam currents ~ 1 A • Test the key components for future linac-ring e-p and e-ion collider

eRHIC with luminosity of 1034 cm-2sec-1 per nucleon – 10-25 GeV SRF ERL for eRHIC– SRF ERL based an FEL -driver for high current polarized electron gun

• Test the attainable ranges of electron beam parameters in SRF ERL


ERL e-Cooler Prototype

ERL circumference [m] ~ 120 ~ 20 Number of passes 1 1 to 2 Beam rep-rate [MHz] 9.38 -28.15 9.38 – 351.875 for tuning 1 Hz – 1 kHz Beam energy [MeV] 54.677 20 - 40 Electrons per bunch (max) 1011 1011 Normalized emittance [m rad] ~ 50 < 50 RMS Bunch length [m] 0.03 – 0.2 0.05 Charge per bunch [nC] 1.6 – 16 1.4 – 10+ Average e-beam current [A] 0.15 – 0.45 0.02 – 0.5 Efficiency of energy recovery 99.9…% > 99.95% Efficiency of current recovery 99.999.…% > 99.9995%

Main Beam parameters for ERLs at Main Beam parameters for ERLs at BNLBNL


Shielded vault for ERL prototype in Bldg. 912


50 kW 703.75 MHzsystem

Control room

Cryo-module

SRF cavity

1 MW 703.75 MHzKlystron

e- 2.5MeV

Laser

SC RF Gun e- 2.5 MeV

Beam dump

Cryo-module

e- 15-20 MeV

30-35 MeV


Main ComponentsMain Components

Gun

SRFlinac

Beamdump

Returnloop


Super Conducting RF 2.5 MeV GunSuper Conducting RF 2.5 MeV Gun with Diamond Amplified Photocathodewith Diamond Amplified Photocathode

Emission enhancement (x 30-80) using a diamond window

Initial conceptual design for a superconducting gun with high quantum efficiency cathode.


Injection into ERLInjection into ERL

20 MeV

2-2.5 MeV

Lambertson septum

Septum-magnet


Standard and optimized merging systemsStandard and optimized merging systems

15-20 MeVfrom ERLFrom the SC RF Gun

2.5 MeV

Laser

Separating magnet

SolenoidSolenoid

Standard

Optimized

x y

x y

Laser

E Eo

Eo

;

const no focusing i

i

0; zii

i

0

E Eo

Eo

;

o zf ( )

(no focusing) i

i

0; zii

i

0; zi2i

i

0


0

2

4

6

8

10

12

14

0 1 2 3 4 5 6 7Length, m

Em

itta

nc

es

, mm

mra

d

Emittance X

Emittance Y

Emittance X

Emittance Y

Emittances X, Y

Results of Parmela simulation for 1 nC e-bunch from the cathode to the end of the linac: black dashed curve is for a round beam passing without bends; blue curves are for a compensated chicane, red curves are for Zigzag merging system.In contrast with where horizontal emittance suffers some traditional chicane growth as result of the bending trajectory, the Z-system (zigzag) the emittances are equal to each other and are very close to that attainable for the straight pass.

Chicane and Zigzag merging systems


The emittance and the dispersion The emittance and the dispersion compensation: compensation:

(Parmela simulation)(Parmela simulation)

0

1

2

3

4

5

6

0

1

2

3

4

5

6

0 1 2 3 4 5 6

x, m

y, m

x, m

y, m,

m

, m

m

S, m

Charge: 1.4 nC/bunchEmittances at Linac enrtance:x ~ 1.7 m, y ~ 1.5 m

Emittances and beam sizes as a function of path length.


Super Conducting 5-cell 703.75 MHz RF Super Conducting 5-cell 703.75 MHz RF linac linac with HOM dampingwith HOM damping

2K main line

Inner magnetic shield

Cavity assembly

4” RF shieldedgate valve

2K fill line

He vessel

Vacuum vessel

Fundamental PowerCoupler assembly

HOM ferriteassembly

Outer magnetic shield

Thermal shield

Tuner location Space framesupport structure

Vacuum vessel


11.2 m3.

7 m

ERL Lattice is very flexibleERL Lattice is very flexible

Lattice of ERL has bilateral symmetry: it comprises of six 60o dipole magnets, twenty five quadrupoles and two solenoids

Lattice functions for the case of zero, positive (2 m) and negotive (-2 m) longitudinal dispersion: Figure shows - and D - functions evaluations along the loop.


Main features of ERLMain features of ERL• Control of m12 for studying the

transverse stability limits in both horizontal and vertical directions

• Control of longitudinal compaction factor for studying longitudinal dynamics

m12 1x2x sinx

m34 1y2y siny

m56 D

ds

x

x

y

y

ctE / E

s2

m11 m12 ... .... ... x

m21 m22 ... ... ... x '

... ... m33 m34 ... y

... ... m43 m44 ... y '

... ... ... ... m55 m56

... ... ... ... ... m66

x

x

y

y

ctE / E

s1

x

x

return

m11 m12

m21 m22

0

x

comming

Excitation process of transverse HOM


• TDBBU, MatTBBU give for ERL with this cavity stability limit: currents up to ~1.8 A (1,800 mA !) for a proper lattice

• We plan to increase M12 in order to measure the TBBU and to compare with predictions by TBBU

Stability of Stability of ERL ERL

(R. Calaga)(R. Calaga)


Plans & ConclusionsPlans & Conclusions

The design and the construction of the R&D ERL is going according to a very aggressive plan

We plan to start commissioning of the R&D ERL in late 2006/early 2007

The prototype ERL will demonstrate the main parameters of the e-beam required for e-cooling

The prototype will also serve as a test bed for studying issues relevant for very high current ERLs and high power FELs

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Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10,...

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