A new ion acceleration method, namely, phase-stable acceleration, using circularly-polarized laser pulses is proposed. When the initial target density n0 and thickness D satisfy aL �� n0=ncD=� L and D>l s with aL, � L, ls, and nc the normalized laser amplitude, the laser wavelength in vacuum, the plasma skin depth, and the critical density of the incident laser pulse, respectively, a quasiequilibrium for the electrons is established by the light pressure and the space charge electrostatic field at the interacting front of the laser pulse. The ions within the skin depth of the laser pulse are synchronously accelerated and bunched by the electrostatic field, and thereby a high-intensity monoenergetic proton beam can be generated. The proton dynamics is investigated analytically and the results are verified by one- and two- dimensional particle-in-cell simulations.

Generating high-current monoenergetic proton beams by a circularly polarized laser pulse in the phase-stable acceleration regime

A rf photocathode electron gun is used as an electron source for ultrafast time-resolved pump-probe electron diffraction. The authors observed single-shot diffraction patterns from a 160nm Al foil using the 5.4MeV electron beam from the Gun Test Facility at the Stanford Linear Accelerator. Excellent agreement with simulations suggests that single-shot diffraction experiments with a time resolution approaching 100fs are possible.

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Ultrafast Time-Resolved Electron Diffraction with Megavolt Electron Beams

Matter manipulation with extreme terahertz light : Progress in the enabling THz technology

The European Spallation Source Design

Particle accelerators represent an indispensable tool in science and industry. However, the size and cost of conventional radio-frequency accelerators limit the utility and reach of this technology. Dielectric laser accelerators (DLAs) provide a compact and cost-effective solution to this problem by driving accelerator nanostructures with visible or near-infrared pulsed lasers, resulting in a 104 reduction of scale. Current implementations of DLAs rely on free-space lasers directly incident on the accelerating structures, limiting the scalability and integrability of this technology. We present an experimental demonstration of a waveguide-integrated DLA that was designed using a photonic inverse-design approach. By comparing the measured electron energy spectra with particle-tracking simulations, we infer a maximum energy gain of 0.915 kilo-electron volts over 30 micrometers, corresponding to an acceleration gradient of 30.5 mega-electron volts per meter. On-chip acceleration provides the possibility for a completely integrated mega-electron volt-scale DLA.

On-chip integrated laser-driven particle accelerator.

1. Introduction 2. RF Accelerator in Linacs 3. Periodic Accelerating Structures 4. Standard Linac Structures 5. Microwave Topics for Linacs 6. Longitudinal Particle Dynamics 7. Transverse Particle Dynamics 8. Radiofrequency Quadrupole Linac 9. Multiparticle Dynamics with Space Charge 10. Beam Loading 11. Wakefields 12. Special Linacs and Special Techniques 13. Superconducting Linacs

RF linear accelerators

RF Acceleration in Linacs Periodic Accelerating Structures Standard Linac Structures Microwave Topics for Linacs Longitudinal Particle Dynamics Transverse Particle Dynamics Radio-Frequency Quadrupole Linac Multiparticle Dynamics with Space Charge Beam Loading Wakefields Special Structures and Techniques Index.

Principles of RF linear accelerators

The PARMTEQ code is used for generating the complete cell design of a radio‐frequency quadrupole linear accelerator and for multiparticle simulation of the beam dynamics. We present a review of the code, with an emphasis on the physics used to describe the particle motion and the cell generation.

PARMTEQ: A beam-dynamics code fo the RFQ linear accelerator

In this paper we review the present picture of km halo in proton linacs. Space-charge forces acting in mismatched beams have been identified as a major cause of beam-halo. We present a definition of halo based on a ratio of moments of the distribution of the beam coordinates. We find from our initial studies that for halo detined in this way, a beam can have rms emittance growth without halo growth, but halo growth is always accompanied by rms emittance growth. We describe the beam-halo experiment that is in preparation at Los Alamos, which will address questions about the beam profiles, maximum particle amplitudes, and rms emittance growth associated with the halo.

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Thomas P. Wangler

Papers

RF linear accelerators

Principles of RF linear accelerators

PARMTEQ: A beam-dynamics code fo the RFQ linear accelerator

Beam Halo in Proton Linac Beams

Standard Linac Structures