The use of infrared lasers to power optical-scale lithographically fabricated particle accelerators is a developing area of research that has garnered increasing interest in recent years. We review the physics and technology of this approach, which we refer to as dielectric laser acceleration (DLA). In the DLA scheme operating at typical laser pulse lengths of 0.1 to 1 ps, the laser damage fluences for robust dielectric materials correspond to peak surface electric fields in the GV/m regime. The corresponding accelerating field enhancement represents a potential reduction in active length of the accelerator between 1 and 2 orders of magnitude. Power sources for DLA-based accelerators (lasers) are less costly than microwave sources (klystrons) for equivalent average power levels due to wider availability and private sector investment. Due to the high laser-to-particle coupling efficiency, required pulse energies are consistent with tabletop microJoule class lasers. Combined with the very high (MHz) repetition rates these lasers can provide, the DLA approach appears promising for a variety of applications, including future high energy physics colliders, compact light sources, and portable medical scanners and radiative therapy machines.

We have measured the wake fields induced by short, intense relativistic electron bunches in a slowwave structure consisting of a dielectric-lined tube, as a test of the dielectric wake-field acceleration mechanism. These fields were used to accelerate a second electron bunch which followed the driving bunch at a variable distance. Results are presented for different dielectrics and beam intensities, and are compared with theoretical predictions.PACS numbers: 52.75.Di

We report the first experimental test of the physics of plasma wake-field acceleration performed

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A dielectric-loaded circular waveguide structure is a potential high-gradient linear wake-field accelerator. A complete solution is given for the longitudinal electric and magnetic fields excited by a 6 function and a Gaussian charge distribution moving parallel to the guide axis. The fields are then given in the limit of particle velocity equal to the speed of light. Example calculations are given for a structure with inner radius of 2 mm, outer radius of 5 mm, dielectric constant of 3, and total charge of 100 nC. Peak wake fields in excess of 200 MV/m are found. Azimuthal modes 0 and 1 are investigated for the particular interest of acceleration and deflection problems.The electromagnetic radiation of a charged particle passing through a structure containing dielectrics' has many applications to accelerator physics. The next generation of electron-positron linear collides will require high-accelerating-gradient ( ) 100 MV/m) structures.Recently a new acceleration scheme, called the dielectric wake-field accelerator, has been proposed. The concept of dielectric wake-field acceleration is very simple. It is a dielectric-lined waveguide and because of its slow wave characteristics it can be used as a wake-field device. In order to make the dielectric structure a practical wakefield acceleration device, however, one has to have high gradients and manageable transverse wake fields. The estimation of the transverse wake-field amplitudes in the dielectric structure is essential because it is directly related to the beam instability (or beam break-up mode) problem. In this paper we calculate both the longitudinal and transverse wake fields produced in a dielectric structure by passing a charged particle. First we give a general expression for the wake fields corresponding to any particle velocity P=U/c including all azimuthal modes m, then discuss the implication of the results under the limit of P~1, in particular for m =0 and l.We should point out that in our previous calculation of the transverse wake field in the dielectric structure, we assumed that the vector potential A was proportional to the scalar potential P. The implication of this assumption was that only TM-like wake fields would be excited, and that no TE-like wake field would exist. The consequence of this was that the higher-order azimuthal-mode m~1 wake fields vanish when the electron beam is ultrarelativistic. This unexpected result attracted much interest in the community. Since then we continued calculations without preassurnptions, as shown in this paper. In the meantime many other people have also investigated this problem, and the results are that both TE and TM waves exist in the dielectric structure for m ) 1 modes. The conclusion of all these works is that the transverse wake fields do not vanish even in the ultrarelativistic limit.Consider the configuration of a metallic tube with inner radius 6, partially filled with isotropic material with dielectric constant e, containing a hole of radius a at the center which allows charged particles to ...

We report a new regime of single-surface multipactor that was observed during high-power testing of an 11.424-GHz alumina-based dielectric-loaded accelerating structure. Previous experimental observations of single-surface multipactor on a dielectric occurred in cases for which the rf electric field was tangential and the rf power flow was normal to the dielectric surface (such as on rf windows) and found that the fraction of power absorbed at saturation is approximately 1%, independent of the incident power. In this new regime, in which strong normal and tangential rf electric fields are present and the power flow is parallel to the surface, the fraction of power absorbed at saturation is an increasing function of the incident power, and more than half of the incident power can be absorbed. A simple model is presented to explain the experimental results.

We report the observation of a strong wakefield induced energy modulation in an energy-chirped electron bunch passing through a dielectric-lined waveguide. This modulation can be effectively converted into a spatial modulation forming microbunches with a periodicity of 0.5-1 ps and, hence, capable of driving coherent terahertz radiation. The experimental results agree well with theoretical predictions.

A strong energy modulation in an electron bunch passing through a dielectric-lined waveguide was recently demonstrated in Antipov et al., Phys. Rev. Lett. 108, 144801 (2012). In this Letter, we demonstrate a successful conversion of this energy modulation into a beam density modulation, and the formation of a series of microbunches with a subpicosecond periodicity by means of magnetic optics (chicane). A strong coherent transition radiation signal produced by the microbunches is obtained and the tunability of its carrier frequency in the 0.68-0.9 THz range by regulating the energy chirp in the incoming electron bunch is demonstrated using infrared interferometry. A tabletop, compact, tunable, and narrowband source of intense THz radiation based on this technology is proposed.