Robert Noble

Experimental Work with Photonic Band Gap Fiber: Building a Laser Electron Accelerator

In the laser acceleration project E‐163 at the Stanford Linear Accelerator Center, work is being done toward building a traveling wave accelerator that uses as its accelerating structure a length of photonic band gap fiber. The small scale of the optical fiber allows radiation at optical wavelengths to be used to provide the necessary accelerating energy. Optical wavelength driving energy in a small structure yields higher accelerating fields. The existence of a speed‐of‐light accelerating mode in a photonic band gap fiber has been calculated previously. This paper presents an overview of several of the experimental challenges posed in the development of the proposed photonic band gap fiber accelerator system.

Optical wakefield from a photonic bandgap fiber accelerator

Photonic Bandgap (PBG) structures have recently been proposed as optical accelerators for their high coupling impedance and high damage threshold. As a first step in preparing a PBG accelerator, we propose to observe the optical wakefield induced by an electron beam traversing the structure in the absence of a coupled laser pulse. The electrons are focused into the fiber via a permanent magnet quadrupole triplet. The electrons excite fiber modes with speed-of-light (SOL) phase velocities. By observing the wakefield using a spectrometer, the SOL mode frequencies are determined.

High Energy Density Physics and Exotic Acceleration Concepts

The reported results and discussions in the Working Group on High Energy Density Physics and Exotic Acceleration Concepts are summarized. The working group focused largely on laser‐generated proton and ion beams from solid targets, but also considered laser vacuum acceleration results, active media accelerator proposals, ferroelectric‐based accelerator technology advances and beam conditioning concepts for free electron lasers. The charge to the working group was to develop a laser‐based proton injector exceeding current capabilities in at least one important parameter.