CST – Computer Simulation Technology

Investigating the Principles of a Dielectric Laser Accelerator

Investigations are currently being made to miniaturize particle accelerators. One of the main approaches to achieve this is by the use of a laser for particle acceleration instead of the conventional method with radio frequency waves. One of the first experiments towards this direction was reported in [1]. The experiment uses a silica grating structure [2] for guiding of particles. An 800 nm mode-locked Ti:sapphire laser is shone across the guiding channel. The acceleration channel consists of surfaces with ridges in order to shape the electric field pattern in a way to enhance energy transfer to electrons.



Figure 1: Model of the silica grating structure, as mentioned in [2] and [3]

This article presents a basic study of this approach via simulation. The laser pulse is realized with a plane wave excitation just above the Silica structure. Pattern of the resulting electric field component along to the beam path is shown in Figure 2. The field has a normal incidence with respect to the beam path. The grating structure provides a periodic modulation of the electric field inside the vacuum channel, according to the principle of periodic field reversal [2]. This results in an overall gain in the energy of particles as they pass through the channel under the influence of this field....



Figure 2: Electric field pattern inside the grating

A 60 MeV electron beam is shot into the guiding channel of the structure. The field simulation of the structure is carried out using the Transient solver in CST STUDIO SUITE®. It is then combined with the PIC solver for a self-consistent simulation to study the interaction between fields and particles. The particles get bunched as they pass through the channel, as can be seen in figure 3.



Figure 3: Particle beam travelling inside vacuum channel of the grating when the laser is on. Particles get bunched as they pass through the channel

References

[1] E. A. Peralta et al., "Demonstration of Electron Acceleration in a Laser-Driven Dielectric Microstructure", Nature (London) (2013)
[2] T. Plettner, P. P. Lu, R. L. Byer, "Proposed few-optical cycle laser-driven particle accelerator structure" Phys. Rev. ST Accel. Beams 9, 111301 (2006)
[3] E. A. Peralta, "Acceleration of electrons in a laser driven dielectric microstructure", NA-PAC'13, Pasadena, CA, (September 30, 2013)
[4] J. England, "Making Accelerators on Microchips", Keynote Address?, SLAC Years of Service Awards (March 19, 2015)

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