SURFACE ELECTROMAGNETIC WAVES IN A GAP BETWEEN TWO LEFT-HANDED MATERIALS

The slow surface electromagnetic waves that propagate along the planar waveguide structure that contains two identical isotropic left-handed material with the vacuum (or air) gap has been considered. The possibility of propagation of slow surface electromagnetic waves of TM and TE polarizations in the frequency range at which the dielectric permittivity and magnetic permeability are negative are shown. By selecting a frequency, one, two or three modes can be excited simultaneously. The group and phase velocities of the TE polarization waves are directed in opposite directions. The frequency range of the existence of the TE mode with an antisymmetric field distribution lies above the frequency range of the existence of the TE mode with a symmetric field distribution. The TM wave, depending on the wavelength, can be either forward or backward, or have zero group velocity. The wave of TM-polarization has a slightly varying group velocity in a sufficiently wide frequency range. A rich set of different properties of these waves make them promising in applications

Beam Dynamics and Tolerance Studies of the THz-driven Electron Linac for the AXSIS Experiment

A dielectric-loaded linac powered by THz-pulses is one of the key parts of the "Attosecond X-ray Science: Imaging and Spectroscopy" (AXSIS) project at DESY, Hamburg. As in conventional accelerators, the AXSIS linac is designed to have phase velocity equal to the speed of light which, in this case, is realized by tuning the thickness of the dielectric layer and the radius of the vacuum channel. Therefore, structure fabrication errors will lead to a change in the beam dynamics and beam quality. Additionally, errors in the bunch injection will also affect the acceleration process and can cause beam loss on the linac wall. This paper numerically investigates the process of electron beam acceleration in the AXSIS linac, taking into account the aforementioned errors. Particle tracking simulations were done using the code ECHO, which uses a low-dispersive algorithm for the field calculation and was specially adapted for the dielectric-loaded accelerating structures.Comment: EAAC'17 conference proceeding

Status and Objectives of the Dedicated Accelerator R&D Facility "SINBAD" at DESY

We present a status update on the dedicated R\&D facility SINBAD which is currently under construction at DESY. The facility will host multiple independent experiments on the acceleration of ultra-short electron bunches and novel, high gradient acceleration methods. The first experiment is the ARES-experiment with a normal conducting 100\,MeV S-band linac at its core. We present the objectives of this experiment ranging from the study of compression techniques to sub-fs level to its application as injector for various advanced acceleration schemes e.g. the plans to use ARES as a test-site for DLA experiments in the context of the ACHIP collaboration. The time-line including the planned extension with laser driven plasma-wakefield acceleration is presented. The second initial experiment is AXSIS which aims to accelerate fs-electron bunches to 15\,MeV in a THz driven dielectric structure and subsequently create X-rays by inverse Compton scattering.Comment: EAAC'17 conference proceeding

Nonlinear theory of wakefield excitation in a rectangular multizone dielectric resonator

A nonlinear self-consistent theory has been constructed and used to investigate numerically the wakefield excitation in multilayered dielectric resonators by relativistic electron bunches. Analytical expressions for solenoidal and potential components of an excited electromagnetic field have been derived. The excitation of a five-zone dielectric resonator by relativistic electron bunches was numerically investigated and comparison was made between the longitudinal distribution of an axial electric field and the results obtained previously for a corresponding problem in the waveguide formulation. The necessity of optimizing geometrical parameters of the resonator to reduce mode amplitudes nonresonant with a bunch, and to obtain a symmetric distribution of the longitudinal electric field component in the drive and accelerating channels, has been demonstrated

Beam Dynamics and Tolerance Studies of the THz-driven Electron Linac for the AXSIS Experiment

A dielectric-loaded linac powered by THz-pulses is one of the key parts of the 'Attosecond X-ray Science: Imaging and Spectroscopy' (AXSIS) project at DESY, Hamburg. As in conventional accelerators, the AXSIS linac is designed to have phase velocity equal to the speed of light which, in this case, is realized by tuning the thickness of the dielectric layer and the radius of the vacuum channel. Therefore, structure fabrication errors will lead to a change in the beam dynamics and beam quality. Additionally, errors in the bunch injection will also affect the acceleration process and can cause beam loss on the linac wall. This paper numerically investigates the process of electron beam acceleration in the AXSIS linac, taking into account the aforementioned errors. Particle tracking simulations were done using the code ECHO, which uses a low-dispersive algorithm for the field calculation and was specially adapted for the dielectric-loaded accelerating structures