1. 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 Linac at BNL

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

3. Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10, 2004 electrons ions Gun Linac 1 Linac 2 Linac 3 Linac 4 Stretcher Compressor electrons ions Beam dump Linac EBIS Booster AGS RHIC II Electron cooling http://www.agsrhichome.bnl.gov/eCool/ Electron cooler for RHIC II project

4. Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10, 2004 Goals for ERL R&D program at BNL Test the key components of the RHIC II electron cooler: –Au-Au luminosity  7x10 27 cm -2 sec -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 10 34 cm -2 sec -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

5. Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10, 2004 Main Beam parameters for ERLs at BNL

6. Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10, 2004 Shielded vault for ERL prototype in Bldg. 912

7. Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10, 2004 50 kW 703.75 MHz system Control room Cryo-module SRF cavity 1 MW 703.75 MHz Klystron e - 2.5MeV Laser SC RF Gun e - 2.5 MeV Beam dump Cryo-module e - 15-20 MeV 30-35 MeV

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

9. Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10, 2004 Super Conducting RF 2.5 MeV Gun with Diamond Amplified Photocathode Emission enhancement (x 30-80) using a diamond window Initial conceptual design for a superconducting gun with high quantum efficiency cathode.

10. Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10, 2004 Injection into ERL 20 MeV 2-2.5 MeV Lambertson septum Septum-magnet

11. Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10, 2004 Standard and optimized merging systems 15-20 MeV from ERL From the SC RF Gun 2.5 MeV Laser Separating magnet Solenoid Standard Optimized Laser 

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

13. Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10, 2004 The emittance and the dispersion compensation: (Parmela simulation) Charge: 1.4 nC/bunch Emittances at Linac enrtance:  x ~ 1.7  m,  y ~ 1.5  m Emittances and beam sizes as a function of path length.

14. Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10, 2004 Super Conducting 5-cell 703.75 MHz RF linac with HOM damping 2K main line Inner magnetic shield Cavity assembly 4” RF shielded gate valve 2K fill line He vessel Vacuum vessel Fundamental Power Coupler assembly HOM ferrite assembly Outer magnetic shield Thermal shield Tuner location Space frame support structure Vacuum vessel

15. Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10, 2004 11.2 m 3.7 m ERL Lattice is very flexible Lattice of ERL has bilateral symmetry: it comprises of six 60 o 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.

16. Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10, 2004 Main features of ERL Control of m 12 for studying the transverse stability limits in both horizontal and vertical directions Control of longitudinal compaction factor for studying longitudinal dynamics Excitation process of transverse HOM

17. Workshop on High Average Power & High Brightness Beams UCLA, Los Angeles, CA, November 8 – 10, 2004 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 ERL (R. Calaga)

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