A compact electron source developed for benchtop linear accelerators

Developing benchtop electron linear accelerators could lead to many applications in a variety of physics experiments. As a step toward this goal, Hirano et al. created a compact and inexpensive electron source for a dielectric laser accelerator (DLA).

Using two electrodes, the authors were able to accelerate and focus electrons from a silicon nanotip emitter to serve as an injector for the DLA. Driven by a pulsed laser beam, the device can generate currents of up to 28 electrons per pulse with the shortest working distance demonstrated to date – in the centimeter scale – an order of magnitude smaller than previously demonstrated.

Though the electron bunches are prone to growth due to space charge effects depending on their initial beam configuration, modifying the working distance can reduce this effect by shortening the length of the reduced field region.

The small size and simple structure of the device, along with its ability to finely focus a sub-micron electron beam spot, make it especially promising for a wide variety of applications ranging from ultrafast electron microscopy to biological imaging.

“We think this additional work will increase the efficiency of DLA, and also will enable the electron source to be applied to a wider range of microscope and diffraction applications,” said author Tomohiko Hirano.

Looking forward, the group plans to focus on increasing the maximum energy and the brightness of the beam. According to Hirano, by increasing the gap between the focusing electrode and the anode, a higher voltage may be used in the electrostatic lens without any major changes to the lens structure.

Source: “A compact electron source for the dielectric laser accelerator,” by Tomohiko Hirano, Karel E. Urbanek, Andrew C. Ceballos, Dylan S. Black, Yu Miao, R. Joel England, Robert L. Byer, and Kenneth J. Leedle, Applied Physics Letters (2020). The article can be accessed at https://doi.org/10.1063/5.0003575 .