Conceptual Design of the Drive Beam for a Pwfa-lc*

Plasma Wake-Field Acceleration (PWFA) has demonstrated acceleration gradients above 50 GeV/m. Simulations have shown drive/witness bunch configurations that yield small energy spreads in the accelerated witness bunch and high energy transfer efficiency from the drive bunch to the witness bunch, ranging from 30% for a Gaussian drive bunch to 95% for bunch with triangular shaped longitudinal profile. These results open the opportunity for a linear collider that could be compact, efficient and more cost effective than the present microwave technologies. A concept of a PWFA-based Linear Collider (PWFA-LC) has been developed by the PWFA collaboration. Here we will describe the conceptual design and optimization of the drive beam, which includes the drive beam linac and distribution system. We apply experience of the CLIC drive beam design and demonstration in the CLIC Test Facility (CTF3) to this study. We discuss parameter optimization of the drive beam linac structure and evaluate the drive linac efficiency in terms of the drive beam distribution scheme and the klystron / modulator requirements. Contributed to the Particle Accelerator Conference, PAC 09, Vancouver, Canada, May 4-8, 2009 ___________________________________________ *Work supported by the DOE under Contract DE-AC02-76SF00515. # [email protected] CONCEPTUAL DESIGN OF THE DRIVE BEAM FOR A PWFA-LC* S. Pei, M. J. Hogan, T. O. Raubenheimer, A. Seryi, SLAC, CA 94025, U.S.A. H. H. Braun, R. Corsini, J. P. Delahaye, CERN, Geneva Abstract Plasma Wake-Field Acceleration (PWFA) has demonstrated acceleration gradients above 50 GeV/m. Simulations have shown drive/witness bunch configurations that yield small energy spreads in the accelerated witness bunch and high energy transfer efficiency from the drive bunch to the witness bunch, ranging from 30% for a Gaussian drive bunch to 95% for bunch with triangular shaped longitudinal profile. These results open the opportunity for a linear collider that could be compact, efficient and more cost effective than the present microwave technologies. A concept of a PWFAbased Linear Collider (PWFA-LC) has been developed by the PWFA collaboration. Here we will describe the conceptual design and optimization of the drive beam, which includes the drive beam linac and distribution system. We apply experience of the CLIC drive beam design and demonstration in the CLIC Test Facility (CTF3) to this study. We discuss parameter optimization of the drive beam linac structure and evaluate the drive linac efficiency in terms of the drive beam distribution scheme and the klystron / modulator requirements.Plasma Wake-Field Acceleration (PWFA) has demonstrated acceleration gradients above 50 GeV/m. Simulations have shown drive/witness bunch configurations that yield small energy spreads in the accelerated witness bunch and high energy transfer efficiency from the drive bunch to the witness bunch, ranging from 30% for a Gaussian drive bunch to 95% for bunch with triangular shaped longitudinal profile. These results open the opportunity for a linear collider that could be compact, efficient and more cost effective than the present microwave technologies. A concept of a PWFAbased Linear Collider (PWFA-LC) has been developed by the PWFA collaboration. Here we will describe the conceptual design and optimization of the drive beam, which includes the drive beam linac and distribution system. We apply experience of the CLIC drive beam design and demonstration in the CLIC Test Facility (CTF3) to this study. We discuss parameter optimization of the drive beam linac structure and evaluate the drive linac efficiency in terms of the drive beam distribution scheme and the klystron / modulator requirements. INTRODUCTION To study new insights of the universe working principle, energy regimes beyond the reach of today’s accelerators need to be explored. The International Linear Collider (ILC) [1] will reach 1⁄2 to 1 TeV C.M. energy with superconducting (SC) microwave technology which provides an acceleration gradient of 35MV/m. For Next Linear Collider (NLC) [2], normal conducting (NC) microwave technology was adopted with reliable gradient of 65MV/m for collider-ready structures. The technology for a Multi-TeV Linear Collider, CLIC [3] is being developed by a world-wide multilateral collaboration of volunteer institutes with NC structures and 100 MV/m accelerating gradients. Plasma Wake-Field Acceleration (PWFA) holds much promise for advancing the energy frontier because it can potentially provide a 1000-fold or more increase in gradient. The experiments conducted at SLAC FFTB have demonstrated a gradient in excess of 50GeV/m can be sustained in an 85 cm-long plasma [4]. Relativistic plasmas can be robust, stable and disposable accelerating structures at ultra-fast timescale (λ ~ 100 μm) compared with SC and NC conventional ones (λ ~ 130 cm). There is no beam break up (BBU) but there is the two-stream instability. Simulations have shown drive/witness bunch configurations that yield small energy spreads in the accelerated witness bunch and high energy transfer efficiency from the drive bunch to the witness bunch, ranging from 30% for a Gaussian drive bunch to 95% for shaped longitudinal profile. Although there may be a tight aligning tolerance between the drive and witness bunches, a plasma accelerator is still one of the most promising routes to a cost-effective TeV-scale linear collider. We developed a concept of PWFA-based Linear Collider (PWFA-LC). Here we will describe the conceptual design and optimization of drive beam, which includes the drive linac and distribution system. We apply experience of the CLIC drive beam design and demonstration in the CLIC Test Facility (CTF3) [5] to this study. We discuss parameter optimization of the drive linac structure and evaluate the efficiency in terms of the drive beam distribution scheme and the klystron / modulator requirements. Drive beam accelerator DR eDR e+ main beam einjector main beam e+ injector Beam Delivery and IR