Terahertz-optical intensity grating for creating high-charge, attosecond electron bunches

Abstract

Ultrashort electron bunches are useful for applications like ultrafast imaging, coherent radiation production, and the design of compact electron accelerators. Currently, however, the shortest achievable bunches, at attosecond time scales, have only been realized in the single-or very fewelectron regimes, limited by Coulomb repulsion and electron energy spread. Using ab initio simulations and complementary theoretical analysis, we show that highly-charged bunches are achievable by subjecting relativistic (few MeV-scale) electrons to a superposition of terahertz and optical pulses. We provide two detailed examples that use realistic electron bunches and laser pulse parameters which are within the reach of current compact set-ups: one with bunches of >240 electrons contained within 20 as durations and 15 μm radii, and one with final electron bunches of 1 fC contained within sub-400 as durations and 8 μm radii. Our results reveal a route to achieve such extreme combinations of high charge and attosecond pulse durations with existing technology.

Tunable free-electron X-ray radiation from van der Waals materials

“…Another significant improvement would be the use of nano-modulated electrons that could make the radiation coherent from multiple electrons (microbunching). These nanomodulated electrons can be generated via emittance exchange techniques [49,50], laser-plasma interactions [51], or electromagnetic intensity gratings [52]. Future work could develop structures that achieve resonant PCB conditions for the interaction between the propagating electrons and the periodic structure in order to improve the emission efficiency of PCB radiation.…”

Space‐Time Wave Packets from Smith‐Purcell Radiation

“…Such attosecond electron bunches can be realized via bunch compression using ultrashort laser pulses. [ 85 , 86 , 87 , 88 ]…”

“…[ 97 , 98 , 99 ] The intensity of space‐time wave packets at terahertz frequencies can be further enhanced by using high‐density field emitter arrays capable of emitting 200 pC electron bunches with 1 mm spot size and 5 ps pulse duration. [ 81 , 82 , 83 , 100 ] At X‐ray frequencies, space‐time wave packets can also be generated from Smith‐Purcell radiation using relativistic electron bunches with nanometer spot size and attoseconds pulse duration, [ 85 , 86 , 87 , 88 ] limited only by the availability of transmission filters at such short wavelength regimes.…”

The Complex Charge Paradigm: A New Approach for Designing Electromagnetic Wavepackets

“…In Figure 4, we see that by appropriately choosing the zeros and poles in Equation ( 6), a self-disrupting behavior can be induced. The on-axis longitudinal field E z , which is critical in applications such as laser-driven particle acceleration [87][88][89] and laser-induced electron pulse compression, [90,91] weakens momentarily before strengthening again and resuming a practically propagation invariant behavior. Figure 5 shows that adjusting the complex charge trajectory can also affect the behavior of the wavepacket as it recovers from the self-disruption, by showing a combination of zeros and poles that changes the symmetric behavior in Figure 4 to an asymmetric evolution in space-time.…”