Femtosecond Planar Electron Beam Source for Micron-Scale Dielectric Wake Field Accelerator

65565 This project will modify a laser-driven vacuum accelerator at Brookhaven National Laboratory to produce a train of ~4 fs electron bunches spaced by 35 fs that can be manipulated to have sheet-like transverse profiles. These microbunches can be used to generate intense accelerating fields in dielectric microstructures, and possibly allow the future design of a high energy electron-positron collider that would be much smaller and less expensive than present technology permits. In Phase I, calculations were conducted to allow optimum chopping of a ~1 ps accelerated bunch into a train of about 30 ~4 fs, ~1-pC electron bunches spaced by 35 fs. A configuration of quadrupole magnets was devised to manipulate transverse profiles of the micro-bunches into sheet-like form. Theory and computations were carried out for wake fields and bunch stability when such bunches transverse planar dielectric accelerator structures. Phase II will install (1) a beam stop for chopping a ~1 ps bunch into a train of about 30 ~4 fs, ~1pC bunches spaced by 35 fs; (2) coherent synchrotron radiation diagnostics to infer the bunch lengths; and (3) quadrupole magnets to manipulate the bunches into sheet-like form for injection into a planar dielectric-lined wake field accelerator structure. Theory and computations will be extended to characterize longitudinal and transverse wake fields in such a structure, including the dynamics and stability of bunches. Commercial Applications and Other Benefits as described by the awardee: The micron-scale planar dielectric wake field accelerator module with acceleration gradient in the range of 1 GV/m should allow for the design and construction of a future TeV-range electron-positron collider that would be much smaller than permitted by current concepts. This could create a market for dozens of accelerators and thousands of planar dielectric structures, amounting to several hundred million dollars