Related papers: Higher-order mode-based cavity misalignment measur…
In order to pursue high-precision beam position measurements for the free-electron laser (FEL) facilities, cavity beam position monitor (CBPM) is employed to measure the transverse position which can meet the requirement of position…
We present a theoretical description of resonant radiofrequency (RF) deflecting cavities in TM$_{110}$ mode as dynamic optical elements for ultrafast electron microscopy. We first derive the optical transfer matrix of an ideal pillbox…
Higher Order Modes (HOM) excited by the beam in the 3.9 GHz accelerating cavities in FLASH can be used for beam position diagnostics, as in a cavity beam position monitor. Previous studies of the modal choices within the complicated…
Modern x-ray free-electron lasers (XFELs) produce x-ray pulses of exceptional transverse coherence. This is due largely to the process of optical guiding by which the radiation is both refractively guided by the bunched electron beam and…
This paper describes an effective frequency doubler scheme for SASE free electron lasers. It consists of an undulator tuned to the first harmonic, a dispersion section, and a tapered undulator tuned to the second harmonic. The first stage…
Phase 1 of the vacuum ultra-violet (VUV) free-electron laser (FEL) at the TESLA Test Facility (TTF) recently concluded operation. It successfully demonstrated the saturation of a SASE FEL in the in the wavelength range of 80-120 nm. We…
Laser wakefield accelerators rely on relativistically moving micron-sized plasma cavities that provide extremely high electric field >100GV/m. Here, we demonstrate transverse shaping of the plasma cavity to produce controlled sub-GeV…
The inner surface of superconducting cavities plays a crucial role to achieve highest accelerating fields. The industrial fabrication of cavities for the European X-Ray Free Electron Laser (EXFEL) and the International Linear Collider (ILC)…
It is shown via theory and simulation that the resonant frequency of a Free Electron Laser may be modulated to obtain an FEL interaction with a frequency bandwidth which is at least an order of magnitude greater than normal FEL operation.…
Length and g-factor are fundamental parameters that characterize optical cavities. We developed a technique to measure these parameters in-situ by determining the frequency spacing between the resonances of fundamental and spatial modes of…
Transverse modes in the 3.9 GHz cavities, designed and fabricated by FNAL, are reported on. These modes have the potential to cause significant emittance dilution if they are not sufficiently suppressed. Recent probe-based-experiments have…
Laser-plasma wakefield acceleration (LWFA) offers ultrahigh accelerating gradients in compact setups, but the complex non-linear nature of the process makes it challenging to generate high-quality beams. Injection of electron bunches from…
The Tera Electronvolt Superconducting Linear Accelerator TESLA is the only linear electron-positron collider project based on superconductor technology for particle acceleration. In the first stage with 500 GeV center-of-mass energy an…
In dark matter searches using axion haloscopes, the search sensitivity depends on the quality factors ($Q_0$) of radiofrequency cavities immersed in multi-tesla magnetic fields. Increasing $Q_0$ would increase the scan rate through the…
Diagnosing free electron laser (FEL) polarization is critical for polarization-modulated research such as x-ray free electron laser (XFEL) diffraction imaging and probing material magnetism. In an electron time-of-flight (eTOF)\…
The third harmonic nine-cell cavity (3.9 GHz) for FLASH and the European XFEL has been investigated using simulations performed with the computer code CST Microwave Studio. The band structure of monopole, dipole, quadrupole and sextupole…
A transverse deflecting structure (TDS) is a well-known device for characterizing the longitudinal properties of an electron bunch in a linear accelerator. The standard use of such a cavity involves streaking the bunch along a transverse…
The possibility of constructing terawatt (TW) x-ray free-electron lasers (FELs) has been discussed using novel superconducting helical undulators [5]. In this paper, we consider the conditions necessary for achieving powers in excess of 1…
This paper presents the experimental realization of an ultrafast electron microscope operating at a repetition rate of 75 MHz based on a single compact resonant microwave cavity operating in dual mode. This elliptical cavity supports two…
High-resolution longitudinal phase-space (LPS) diagnostics are essential for X-ray free-electron lasers and advanced accelerators. Conventional radio-frequency transverse deflecting structures (TDSs) provide direct femtosecond-scale LPS…