Electron Acceleration with Tilted Laser Pulses
Beams of charged particles have been used for many years by the scientific community for various applications such as high-energy particle physics, materials processing, terahertz radiation generation, and medical therapies. To produce beams with a tight tolerance for angle and energy range is quite challenging. We are investigating a new approach where we use the pressure of light on electrons (the ponderomotive force) to accelerate electrons. With a conventional focused ultrafast laser pulses, the potential hill that accelerates electrons moves too fast for electrons to catch the wave. In our approach, we shape the pulse so that it has a strong tilt. This has the effect of slowing down the interaction of the moving potential hill so that all of the electrons are captured and accelerated. The effect is like an angled snowplow that pushes the snow to the side as the plow moves forward. By shaping the beam to make the pulse as flat as possible, we are working toward showing that this can be a viable way to accelerate electrons to energies approaching the speed of light (MeV range), with tight angle and energy tolerances. These bunches of electrons we create could see application as an injector stage for larger accelerators, as a “light” source for ultrafast electron diffraction, or as a driver terahertz radiation.
The GIF above shows the acceleration of a single electron by a tilted ultrafast laser pulse.