New Technologies for Accelerators - Advanced Accelerator Research - Bob Siemann March 19, 2003 Introduction An Incomplete Survey Plasma Waves and The Afterburner A Laser Driven Linear Collider Conclusion

Science  Innovation Particle Physics Discoveries 2 ’s J/  W & Z top Accelerator Innovations Phase focusing Klystron Strong focusing Colliding beams Superconducting magnets Superconducting RF

Innovation is Critical The Livingston Curve Captures our history Expresses our aspirations But there is no guarantee Approaches that have become too big, too expensive, … have been supplanted - Vital for advancing science

Accelerator Science & Technology Evolution & Maturity Underlying science & technology Developing a design => parameter lists, etc Optimization Construction Commissioning & operation Advanced accelerator research = high gradient e + e - acceleration Advanced accelerator research is one aspect of accelerator innovation

An Incomplete Survey mm-wave accelerator fabricated by deep x-ray lithography R. Kustom et al, ANL Dielectric wakefield accelerator – Two beam experiment W. Gai et al, ANL

An Incomplete Survey Shot 12 (10 kG) Shot 26 (10 kG) Shot 29 (5 kG) Shot 33 (5 kG) Shot 39 (2.5 kG) Shot 40 (2.5 kG) Relative # of electrons/MeV/Steradian Electron energy (in MeV) SM-LWFA electron energy spectrum Self modulated laser wakefield acceleration E > 100 MeV, G > 100 GeV/m A. Ting et al, NRL Active medium Trigger bunch Amplified wake Accelerated bunch Wakefield amplification by an active medium L. Schächter, Technion

An Incomplete Survey Plasma Focusing of e + beams P. Chen et al, SLAC Transport of an e - beam through a 1.4 m long plasma P. Muggli et al, USC

Advanced Accelerator Physics at SLAC T. Katsouleas, S. Deng, S. Lee, P. Muggli, E. Oz University of Southern California B. Blue, C. E. Clayton, V. Decyk, C. Huang, D. Johnson, C. Joshi, J.-N. Leboeuf, K. A. Marsh, W. B. Mori, C. Ren, J. Rosenzweig, F. Tsung, S. Wang University of California, Los Angeles R. Assmann, C. D. Barnes, F.-J. Decker, P. Emma, M. J. Hogan, R. Iverson, P. Krejcik, C. O’Connell, P. Raimondi, R.H. Siemann, D. R. Walz Stanford Linear Accelerator Center UCLA Beam-Driven Plasma Acceleration: E-157, E-162, E-164, E-164X C. D. Barnes, E. R. Colby, B. M. Cowan, M. Javanmard, R. J. Noble, D. T. Palmer, C. Sears, R. H. Siemann, J. E. Spencer, D. R. Walz Stanford Linear Accelerator Center R. L. Byer, T. Plettner, J. A. Wisdom Stanford University T. I. Smith, R. L. Swent Y.-C. Huang Hansen Experimental Physics Laboratory National Tsing Hua University, Taiwan L. Schächter Technion Israeli Institute of Technology Vacuum Laser Acceleration: LEAP, E-163

Physical Principles of the Plasma Wakefield Accelerator Space charge of drive beam displaces plasma electrons Wake Phase Velocity = Beam Velocity (like wake on a boat) Plasma ions exert restoring force => Space charge oscillations Wake amplitude electron beam Ez

Z Radius electron positron Flow-in Blow-out e+e+ e-e- Radius Electrons and Positrons in Plasmas

� Double the energy of Collider w/ short plasma sections before IP � 1 st half of beam excites wake --decelerates to 0 � 2 nd half of beams rides wake--accelerates to 2 x E o � Make up for Luminosity decrease  N 2 /  2 by halving  in a final plasma lens 50 GeV e - 50 GeV e + e - WFA e + WFA IP LENSES The Afterburner Idea

Located in the FFTB Experimental Layout for Beam Plasma Experiments Runs 2&3, Summer 2001 e + acceleration, e - acceleration

Average energy loss (slice average) : 159±40 MeV Average energy gain (slice average) : 156 ±40 MeV E-162: Longitudinal Dynamics Part 4 Preliminary Energy Loss & Gain

An e + e - Linear Collider L, E CM e+ e- Damping Ring Power Source Final Focusing SystemLinear Accelerator Particle Source

Luminosity, Beam Power & Efficiency

Efficiency and Scalability of Power Sources TUBES FEMs FELsLASERS (RF Compression, modulator losses not included) Yb:KGd(WO 4 ) 2 =1.037   t =112 fsec P ave =1.3 W  =28% SLAC PPM Klystron =2.624 cm  t =3  sec P ave =27 kW  =65% Source Frequency [GHz] Source Efficiency [%] Carrier Phase-Lock of a Laser M. Bellini, T Hansch, Optics Letters, 25 (14), p.1049, (2000). Eric Colby 10/15/2002

Carrier Phase-Locked Lasers Diddams et al “Direct Link between Microwave and Optical Frequencies with a 300 THz Femtosecond Laser Comb”, Phys. Rev. Lett., 84 (22), p.5102, (2000).

Luminosity, Beam Power & Efficiency

Structure Efficiency q = 0,  because no charge is accelerated  because when  = 0  =  max  = 0 All the laser energy radiated away into broad band radiation q/q max  /  max

PBGFA Efficiency X. Lin, Phys. Rev. ST-AB, 4, (2001). The estimate of Z H ignores the other air tunnels and the frequency dependence of the dielectric constant

Charge Limit 1.There is a maximum charge/bunch based on efficiency 2.It is uncertain because Z H is uncertain PBGFA: frequency dependence of  LEAP: multiple slit interference 3.Multiple beam bunches/laser pulse Required for high efficiency PBGFA:  is already long to fill structure => make it slightly longer to accelerate multiple bunches LEAP:  >>  min => accelerate multiple bunches or waste energy

Concluding Remarks energy stored in the laser cavity acceleration structure incorporate the acceleration structure in the laser cavity  Recycling (M. Tigner). All laser based schemes rely on the fact that a relatively small fraction of the energy stored in the laser cavity is extracted and used in the acceleration structure. Conceptually, it seems possible to take advantage of the high intensity electromagnetic field that develops in the cavity and incorporate the acceleration structure in the laser cavity.  According to estimates, the rep-rate of each macro-bunch is 1GHz and each macro-bunch is modulated at the resonant frequency of the medium (e.g  m). compensated by the active mediumnarrow band wake  The amount of energy transferred to the electrons or lost in the circuit is compensated by the active medium that amplifies the narrow band wake generated by the macro-bunch. Levi Schächter 10/11/02 (But not for this talk)

A Parameter List Beam is assumed debunched at the IP

An e + e - Linear Collider L, E CM e+ e- Damping Ring Power Source Final Focusing SystemLinear Accelerator Particle Source

STELLA (Staged Electron Laser Acceleration) experiment at the BNL ATF Source: W. Kimura, I. Ben-Zvi. Bunching & Phase Control At = 10  m

Particle Source GeV  1.25  particles/second 10 6 – 10 7 / 1 psec long bunch spaced at 50 MHz ~100 optically spaced bunches in the 1 psec bunch Bunches spaced at harmonic of 50 MHz IFEL to bunch and accelerate at Continuous injection Low energy for low  I and to have IFEL bunching Do not know how to extract!

Science  Innovation Advanced Accel. R&D