ABSTRACT
This paper presents the design, prototype engineering, and initial testing of a relatively low-voltage, high aspect ratio electron gun for versatile pulsed power applications. The sheet beam, diode electron gun is designed for (23-25) kV voltage and 6 µA/V1.5, as is required for x-band klystron, as a part of a compact Klylac delivering electron beam energy in the MeV range. The gun prototype was engineered, built, and tested using a Scandinova M1-0.5 modulator. Beam loss on the anode aperture is evaluated from transient waveforms and equivalent circuit modeling.
ABSTRACT
X-ray free-electron lasers (XFELs) deliver intense x-ray pulses that destroy the sample in a single shot by a Coulomb explosion. Experiments using XFEL pulse trains or the new generation of high-repetition rate XFELs require rapid sample replacement beyond those provided by the systems now used at low repletion-rate XFELs. We describe the development and characterization of a system based on a spinning disk to continuously deliver a solid sample into an XFEL interaction point at very high speeds. We tested our system at the Linac Coherent Light Source and European XFEL hard x-ray nano-focus instruments, employing it to deliver a 25 µm copper foil sample, which can be used as a gain medium for stimulated x-ray emission for the proposed x-ray laser oscillator.
ABSTRACT
Although linear accelerators are used in many security, industrial and medical applications, the existing technologies are too large and expensive for several critical applications such as radioactive source replacement, field radiography and mobile cargo scanners. One of the main requirements for these sources is to be highly portable to allow field operation. In response to this problem, RadiaBeam has designed a hand-portable 1 MeV X-ray source, scalable to higher energies, based on Ku-band split electron linac, that can be used for Ir-192 radioisotope replacement. In this paper, we present its multiphysics and engineering design studies, as well as an accelerating structure prototype along with RF measurements.
Subject(s)
Iridium Radioisotopes/chemistry , Particle Accelerators , Electrons , Equipment DesignABSTRACT
RadiaBeam has developed a 6 MeV accelerator that is compact and light enough to be placed on a robotic arm or light truck. The main drivers of size and weight in conventional accelerators are the power source and the shielding. Small dimensions are enabled by operation at 9.3 GHz frequency (X-band), which allows reducing the size and weight of all accelerator components. Thanks to the robust design of the accelerating structure, the accelerator can be used as a source for novel cargo inspection and radiotherapy techniques. In this paper, we present the linac design and its components, as well the results of the experimental demonstration of beam acceleration.
ABSTRACT
Conventional thermionic microwave and radio frequency (RF) guns can offer high average beam current, which is important for synchrotron light and terahertz (THz) radiation source facilities, as well as for industrial applications. For example, the Advanced Photon Source at Argonne National Laboratory is a national synchrotron-radiation light source research facility that utilizes thermionic RF guns. However, these existing thermionic guns are bulky, difficult to handle and install, easily detuned, very sensitive to thermal expansion, and due for a major upgrade and replacement. In this paper, we present the design of a new, more stable, and reliable gun with optimized electromagnetic performance, improved thermal engineering, and a more robust cathode mounting technique, which is a critical step to improve the performance of existing and future light sources, industrial accelerators, and electron beam-driven THz sources. We will also present a fabricated gun prototype and show results of high-power and beam tests.
ABSTRACT
Observation of ultrawide bandwidth, up to 15% full-width, high-gain operation of a self-amplified spontaneous emission free-election laser (SASE FEL) is reported. This type of lasing is obtained with a strongly chirped beam (deltaE/E approximately 1.7%) emitted from the accelerator. Because of nonlinear pulse compression during transport, a short, high current bunch with strong mismatch errors is injected into the undulator, giving high FEL gain. Start-to-end simulations reproduce key features of the measurements and provide insight into mechanisms, such as angular spread in emitted photon and electron trajectory distributions, which yield novel features in the radiation spectrum.
ABSTRACT
VISA (Visible to Infrared SASE Amplifier) is a high-gain self-amplified spontaneous emission (SASE) free-electron laser (FEL), which achieved saturation at 840 nm within a single-pass 4-m undulator. The experiment was performed at the Accelerator Test Facility at BNL, using a high brightness 70-MeV electron beam. A gain length shorter than 18 cm has been obtained, yielding a total gain of 2 x 10(8) at saturation. The FEL performance, including the spectral, angular, and statistical properties of SASE radiation, has been characterized for different electron beam conditions. Results are compared to the three-dimensional SASE FEL theory and start-to-end numerical simulations of the entire injector, transport, and FEL systems. An agreement between simulations and experimental results has been obtained at an unprecedented level of detail.
