THz-based phase-space manipulation of electron bunches

We propose a “zero-slippage,” inverse free electron laser that uses a waveguide to sustain the interaction by matching the group velocity of a THz pulse to an electron bunch. The THz pulse, produced by optical rectification of the same initial laser pulse which generates the electron bunch, will create a ponderomotive potential that reduces the time-of-arrival jitter of the electron bunch as it is rotated in longitudinal phase space. We have demonstrated the direct coupling of the THz pulse into a parallel plate waveguide and measured the resulting group velocity reduction. Initial simulations predict compression of 1 pC, 100 fs (rms) electron bunches generated at UCLA’s Pegasus laboratory by up to a factor of 10, along with an order-of-magnitude reduction in time of arrival jitter.