Plasma photocathodes and ultrabright beams

While plasma wakefield acceleration provides 1000x stronger acceleration gradients than conventional accelerators, the plasma photocathode can generate electron beams that are 10,000x or 100,000x brighter than state-of-the-art. The secret is to release cold matter within plasma wakefield accelerators with laser pulses focused just above the tunneling ionization threshold of matter. This achieves that the residual transverse momentum of the laser pulse is extremely low. Because of this, and because the electron release is very localized, the so called emittance of the electron beams is very small, reaching values of the normalized transverse emittance of only few tens of nanometre-radian or even less. After release, the electrons are compressed and accelerated in the wakefield and constitute very short bunches of duration of a few femtoseconds or less, and corresponding currents of kA or multi-kA.  

Photo from: B. Hidding et al., Phys. Rev. Lett. 108, 035001 (2012)

Ultracold Electron Bunch Generation via Plasma Photocathode Emission and Acceleration in a Beam-driven Plasma Blowout, B. Hidding, G. Pretzler et al., Physical Review Letters 108, 035001, (2012)

Optical plasma torch electron bunch generation in plasma wakefield accelerators, Wittig, G., ..  Hidding, B., Physical Review Special Topics: Accelerators and Beams. 18, 8, 081304 (2015)

Generation and acceleration of electron bunches from a plasma photocathode, A. Deng.. B. Hidding, Nature Physics 15, 1156-1160 (2019)

Stable witness-beam formation in a beam-driven plasma cathode A. Knetsch .. B. Hidding et al., Phys. Rev. Accel. Beams 24, 101302 (2021)