Accelerating structures operating in Ka-Band are foreseen to achieve gradients around 150 MV/m. Among possible applications of a Ka-Band accelerating structure we refer to the beam phase-space manipulation for the Compact Light XLS project as well as medical and industrial applications. In this paper, a Ka-Band Klystron amplifier is being investigated in order to feed Ka-Band accelerating structures. The initial design is presented including the high-power DC gun and the beam focusing channel.
Self consistent analytic and numeric design for a set of electron guns with a high beams quality to be used in high power Ka-band klystrons are presented in this paper. The set of electron guns can be used in the high power Ka-band klystrons in order to feed linear accelerating structures at 36 GHz with an estimated 20 MW input power by achieving an effective accelerating electric field in the (100-150) MV/m range. In the framework of the Compact Light XLS project, a short Ka-band linearizer by working at 36 GHz able for providing an integrated voltage of at least 15 MV is proposed for bunch-p…
In the framework of the Compact Light XLS project, a short ultra-high gradient linearizer working on the third harmonic of the main LINAC frequency is requested. Increasing gradients and reducing dimensions are requirements for XLS and all next generation linear accelerators. Actually, ultra-compact normal conducting accelerating structures, operating in the Ka-band regime ranging from 100 to 150 MV/m are required to achieve ultra-high gradients for research, industrial and medical applications. To fulfill these strong requirements, the R$\&$D of a proper Ka-band klystron with RF power output …
Advanced technical solution for the design of a low perveance electron gun with a high quality beam dedicated to high power Ka-band klystrons is presented in this paper. The proposed electron gun can be used to feed linear accelerating structures at 36 GHz with an estimated input power of 20 MW, thus achieving an effective accelerating electric field in the (100-150) MV/m range. additionally, in the framework of the Compact Light XLS project, a short Ka-band accelerating structure providing an integrated voltage of at least 15 MV, has been proposed for bunch-phase linearization. For the klystr…
A new frequency converter, operating at significantly higher power and efficiency than previous devices, is described in this paper. The proposed device is implemented as a klystron structure where a new design principle is used. New analytical formulas and a specific design procedure are proposed. The klystron frequency multiplier can be suitable for telecommunications and non-lethal weapon, scientific and medical particle accelerators while the most interested exploitations are in the field of high gradient particle acceleration and FEL devices for which no performant sources exist. The adva…
The design and performance analysis of DC electron gun for 5045 S-band klystron has been worked out using SLAC beam trajectory program (EGUN) and Computer Simulation Technology Particle Studio (CST-PS), Codes. Specifications of electron gun were focused on beam; current, perveance, size and emittance. Optimized beam; current, perveance, diameter and emittance were 414.00A, 2.00uP, 26.82 mm and 103.10 pi mm mrad, respectively. Furthermore, the optimized characteristic parameters of the gun were also calculated and compared with the simulated and experimental values which were in agreement. Accu…
A high power microwave system based on power combining and pulse compression of conventional klystrons is introduced in this paper. This system mainly consists of pulse modulator, power combiner, driving source of klystrons and pulse compressor. A solid state induction modulator and pulse transformer were used to drive two 50 MW S-band klystrons with pulse widths 4 μs in parallel, after power combining and pulse compression, the tested peak power had reached about 210 MW with pulse widths nearly 400 ns at 25 Hz, while the experimental maximum output power was just limited by the power capacity…
A progogype 5-GHz 500-kW CW klystron (model E3762 provided by Toshiba Electron Tubes & Devices Co. Ltd.) has been operating as the RF source for the lower hybrid current drive (LHCD) system in the KSTAR tokamak. In order to investigate how the efficiency of the 5-GHz 500-kW CW klystron prototype could be enhanced, the cavity design study is being carried out with simulation code based on the main klystron operation parameters. This is being done by simulating klystron performances for various cavity parameters including the number of cavities, inter-cavity distance, and cavity tuning frequenci…
Initial test results of an L-band multi-beam klystron with parameters relevant for ILC are presented. The chief distinction of this tube from MBKs already developed for ILC is its low operating voltage of 60 kV, a virtue that implies considerable technological simplifications in the accelerator complex. To demonstrate the concept underlying the tubes design, a six-beamlet quadrant (a 54 inch high one-quarter portion of the full 1.3 GHz tube) was built and recently underwent initial tests, with main goals of demonstrating rated gun perveance, rated gain, and at least one-quarter of the full 10-…
An e+e- linear collider at 500-GeV C.M. (center of mass) has been proposed as a future accelerator. The C-band linear collider has more than a thousand klystrons and matching modulators. The linear colliders require smart modulators with high reliability, compact and simple configuration, and good power efficiency. This study suggests solutions to problems expected in the future linear colliders. A C-band smart modulator has been developed using a constant-current inverter power supply. The smart modulator provides 350-kV pulses of the pulse-to-pulse stability of 0.35%, the pulse-width of 4.35…
KEK-ATF is studying low emittance, multi-bunch electron beam for the future linear collider. The energy instability of the 1.5 GeV linac has been a problem making the beam injection to the damping ring unstable. Because the unstable beam generates also large amount of the radiation, the beam current is limited by the KEK radiation safety policy much lower than what we expect. Stabilizing the S-band linac is therefore important not only to improve the beam quality, but also to clear the radiation safety limit to start the multi-bunch operation. We have made various modifications to solve the pr…
In the framework of the upgrade of the SPARC_LAB facility at INFN-LNF, named EuPRAXIA@SPARC_LAB, a high gradient linac is foreseen. One of the most suitable options is to realize it in X-band. A preliminary design study of both accelerating structures and power distribution system has been performed. It is based on 0.5 m long travelling wave (TW) accelerating structures operating in the 2π/3 mode and fed by klystrons and pulse compressor systems. The main parameters of the structures and linac are presented with the basic RF linac layout.
An S-band linear accelerator is the source of particles and the front end of the Advanced Photon Source injector. In addition, it supports a low-energy undulator test line (LEUTL) and drives a free-electron laser (FEL). A waveguide-switching and distribution system is now under construction. The system configuration was revised to be consistent with the recent change to electron-only operation. There are now six modulator-klystron subsystems, two of which are being configured to act as hot spares for two S-band transmitters each, so that no single failure will prevent injector operation. The t…
The two-frequency heating technique was studied to increase the beam intensities of highly charged ions provided by the high-voltage extraction configuration (HEC) ion source at the National Institute of Radiological Sciences (NIRS). The observed dependences on microwave power and frequency suggested that this technique improved plasma stability but it required precise frequency tuning and more microwave power than was available before 2013. Recently, a new, high-power (1200 W) wide bandwidth (17.1-18.5 GHz) travelling-wave-tube amplifier (TWTA) was installed. After some single tests with klys…
In the development of high efficiency and high gradient RF-accelerators, RF waveguides and cavities have been designed with Photonic Band Gap (PBG) and fishnet- metamaterial structures. The designed structures are comprised of a periodically corrugated channel sandwiched between two photonic crystal slabs with alternating high to low dielectric constants and a multi-cell cavity-resonator designed with fishnet-metamaterial apertures. The structural designs of our interest are intended to only allow an operating-mode or -band within a narrow frequency range to propagate. The simulation analysis …
We report the results of high gradient testing of two single cell off axis coupled standing wave accelerating structures. Two brazed standing wave side coupled structures with the same geometry were tested one made of pure copper Cu and one made of a copper silver CuAg alloy with silver concentration of 0.08 percent. A peak surface electric field of 450 MV per m was achieved in the CuAg structure for a klystron input power of 14.5 MW and a 1 mirco s pulse length which was 25 percent higher than the peak surface electric field achieved in the Cu structure. The superb high gradient performance w…
The Compact Linear Collider (CLIC) is a TeV-scale high-luminosity linear $e^+e^-$ collider under development by international collaborations hosted by CERN. This document provides an overview of the design, technology, and implementation aspects of the CLIC accelerator. For an optimal exploitation of its physics potential, CLIC is foreseen to be built and operated in stages, at centre-of-mass energies of 380 GeV, 1.5 TeV and 3 TeV, for a site length ranging between 11 km and 50 km. CLIC uses a Two-Beam acceleration scheme, in which normal-conducting high-gradient 12 GHz accelerating structures…
The Compact Linear Collider (CLIC) is a TeV-scale high-luminosity linear e$^+$e$^-$ collider under development by international collaborations hosted by CERN. This document provides an overview of the design, technology, and implementation aspects of the CLIC accelerator and the detector. For an optimal exploitation of its physics potential, CLIC is foreseen to be built and operated in stages, at centre-of-mass energies of 380 GeV, 1.5 TeV and 3 TeV, for a site length ranging between 11 km and 50 km. CLIC uses a two-beam acceleration scheme, in which normal-conducting high-gradient 12 GHz acce…
Charged particle therapy, or so-called hadrontherapy, is developing very rapidly. There is large pressure on the scientific community to deliver dedicated accelerators, providing the best possible treatment modalities at the lowest cost. In this context, the Italian research Foundation TERA is developing fast-cycling accelerators, dubbed 'cyclinacs'. These are a combination of a cyclotron (accelerating ions to a fixed initial energy) followed by a high gradient linac boosting the ions energy up to the maximum needed for medical therapy. The linac is powered by many independently controlled kly…
