Increasing the output power of microwave is one most important development directions for high-power (HPM) technology. However, when increased, radio frequency breakdown would occur owing to superhigh electric field strength. This problem limits handling capability a single-HPM generator, and this becomes more serious high-frequency bands long pulse. One solution overcome coherent combining, combining can achieve an equivalent order mymargin TW. The relativistic klystron amplifier (RKA)...

We proposed an oversized coaxial multi-beam relativistic klystron amplifier (OCMB-RKA) with a new input coupler of lesser complexity giving enhanced microwave power absorption rate for generating high millimeter-wave radiation in Ka-band. The high-frequency structure the OCMB-RKA was designed, fabricated, and cold-tested results that agreed well simulated results. Furthermore, using 3D particle-in-cell (PIC) code, beam-wave interaction simulated, considering two different materials...

The sheet beam relativistic extended interaction oscillator (REIO) is a very important high-power millimeter-wave source for many actual and potential applications. A Ka-band REIO designed by means of particle-in-cell (PIC) simulation. In the design, we adopt electron with dimensions 45 mm × 1.5 to reduce space charge effect cavities increase power capacity. results PIC simulation demonstrate device can generate an output 404 MW at 30 GHz efficiency 20%. addition, develop experiment on...

To improve the output power and electron efficiency broaden operating bandwidth, three-gap extended cavity was used in relativistic klystron to replace single-gap cavity. The high-frequency characteristics of were studied. load conductance derived corrected based on theory relativity, by which a more accurate relation versus transmit angle can be obtained. characteristic impedance is three times bigger than that under case <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML"...

To achieve gigawatt-level amplification output radiation in X-band, an X-band coaxial multibeam relativistic klystron amplifier is designed. When the diode voltage and current are increased to obtain higher power, modes can seriously degrade Klystron performance cause pulse shortening. Special measures introduced device suppress mode excitation avoid Finally, shortening avoided amplifier. Output power of 2.1 GW with efficiency 40% obtained particle-in-cell simulation when driven microwave...

To realize coherent high power microwave combining, an X-band long pulse multibeam relativistic klystron amplifier is designed, and the relative phase stability investigated by three dimensions particle in cell simulation experiment. The shows that difference can be stabilized at gigawatt level radiation power. But jitter increases experiment, then some measures are proposed to improve of avoid shortening. A 0.98 GW with duration 160 ns obtained shortening avoided. fluctuation between output...

This letter reports the successful development of an S-band short-length, high-efficiency, coaxial cavity multi-beam relativistic klystron amplifier (CCMB-RKA). The simulation in one-dimensional genetic algorithm, capable giving high-efficiency parameters, predicted 67% efficiency CCMB-RKA, taking interaction length as 600 mm, beam voltage 420 kV, and current 230 A. However, for accurate results, CCMB-RKA was simulated again using three-dimensional code CHIPIC, RF input power, voltage, 4.4...

To achieve a gigawatt-level long pulse radiation power in X-band, multi-beam relativistic klystron amplifier is proposed and studied experimentally. By introducing 18 electron drift tubes extended interaction cavities, the capacity of device increased. A 1.23 GW with efficiency 41% gain 46 dB obtained particle-in-cell simulation. Under conditions 10 Hz repeat frequency an input RF 30 kW, 0.9 GW, 9.405 GHz, duration 105 ns, 30% generated experiment, about 45 dB. Both simulation experiment...

We propose a novel system of input and output couplers, excited in azimuthal symmetric stable mode operation, for an oversized coaxial relativistic klystron amplifier (OCRKA) at Ka-band. A converter is introduced the waveguide to provide tunnel fix inner outer conductors OCRKA. After characterizing proposed high-frequency structure OCRKA designed then optimized by Computer Simulation Technology. The simulated frequency loaded quality factor input, output, idler cavities are validated against...

In this brief, a compact high-gain Ku-band multibeam relativistic klystron amplifier (MBRKA) is proposed to achieve high power and efficiency with low-guiding magnetic field. A special anode structure an inner conductor designed realize stable transmission of the intense multiple electron beams (IRMEBs) The compactness realized by adopting three cascaded double gap bunching cavities while maintaining gain. MBRKA be over mode increase capacity. Combined device structure, internal external...

An X-band coaxial multi-beam relativistic klystron amplifier is designed in order to increase output microwave power and operating frequency of the tube. The experiment performed on a Tesla-type accelerator. driven by an electron beam 2.8 kA at 720 kV, 30 kW 9.384 GHz injected into input cavity means external source, then over 800 MW extracted, gain about 44 dB, conversion efficiency 40%. proves that nearly GWs can be generated with kW-level power.

In this paper, an extended interaction oversized coaxial relativistic klystron amplifier (EIOC-RKA) with Gigawatt-level output at Ka band is proposed. We introduce the and multi-gap resonant cavities to increase power capacity investigate a non-uniform cavity improve electronic efficiency of EIOC-RKA. develop high order mode gap in input easily design fabricate couplers. Meanwhile, we EIOC-RKA by using particle-in-cell simulation. simulations, use electron beam current 6 kA voltage 525 kV,...

The power capacity of an individual high microwave (HPM) generator is severely limited by internal electric field breakdown, and the problem becomes more serious for long pulse frequency bands. One promising solutions to overcome this limitation coherent combination in space. To realize space, HPM generators must operate at same stable phase differences. We presented improved X-band gigawatt coaxial multi-beam relativistic klystron amplifier (CMB-RKA) with stability. Two double gap buncher...

In this paper, an oversized coaxial relativistic extended interaction oscillator (OCREIO) with gigawatt-level output at the Ka-band is proposed. We adopt a four-gap buncher cavity and three-gap to increase power capability improve electronic efficiency of OCREIO. The beam-loading conductance for each mode existing in derived based on small-signal theory. beam-wave 2π/3 π modes exciting are analyzed. operation chosen by considering capability. addition, improved method proposed mitigate...

In this letter, the stability of an X band gigawatt coaxial multi-beam relativistic klystron amplifier (CMB-RKA) operating in repetitively pulsed mode was investigated by particle-in-cell (PIC) simulation and experiments. A four-gap extended-interaction output cavity optimized to avoid electrons reflection. And a water-cooled electron beams collector which integrated with converter designed reduce plasma secondary electrons. The explosive emission conditions were improved using C–C composite...

In order to improve the power and gain of a long-pulse relativistic klystron amplifier (RKA), simulation experimental studies an S-band RKA driven by long pulse intense electron beams (IREBs) were carried out. We investigated phenomena self-excitation shortening, their roots, suppression measures in process IREB modulation microwave extraction. The research results show that reflection electrons transmission high modes drifting tube, which are excited at output cavity, main origins...

The design, based on theory, simulation, and cold as well hot tests, is proposed for a compact GW-level multibeam relativistic klystron amplifier (MB-RKA) with low beam confining magnetic field in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}$ </tex-math></inline-formula> -band, which can operate repeatedly stably up to 8 min. For this purpose, graphene cathodes microchannel water cooling system...

The effects of spatial nonuniformity electron multibeam emission on the output characteristics a coaxial Ka-band relativistic klystron amplifier (RKA) are investigated using particle-in-cell simulations. is simulated four different models, with (1) continuous cathode non-emission area, (2) discontinuous areas, (3) areas current densities, and (4) time-varying densities. simulation results first model show that microwave power RKA decreases as area increases, but size has little effect...

Traditional computer forensic tools suffer from several drawbacks: 1) information recorded by the operating system and application may not be enough for performing exact forensics, because such is tailored purpose; 2) evidence extraction based on single computer; 3) vulnerable to tampered; 4) volatile yet important analysis. To overcome these limitations, this paper proposes a cloud-based proactive forensics framework record state across set of computers (such as cluster that consist cloud)...

Generally, image rendering requires high computing capacity. It is really time consuming to render a movie on single machine. The use of multiple machines move much effort control the workflow and data. With emergence cloud computing, more scientists engineers are moving their tasks from laboratories public clouds. This migration some sort experience both architecture coding in cloud. paper proposes simple service movies Microsoft Azure that accelerates rendering. service, called...

In this study, an oversized coaxial output cavity is proposed for a Ka band relativistic klystron amplifier (RKA). It consists of three-gap resonator and coupler. To ensure the concentricity, double-row supporting rods are used in cavity. The parameters obtained through theoretical analysis CST simulation. addition, authors evaluate performance by using particle-in-cell software CHIPIC. They investigate influences period length external quality factor on power. Furthermore, they study effect...

The influence of electron beam uniformity on the microwave characteristics coaxial structure Ka-band RKA output cavity is investigated with particle-in-cell simulations. non-uniformity simulated in four different emission models: (1) continuous non-emission area, (2) spaced emission, (3) enhanced and (4) current density variation emission. simulation results first model shows that power decreases as area increases, while has little effect frequency pulse width microwave; second related to...

An experimental study of an intense current electron beam diode with a foil-free annular graphite cathode is carried out. The explosive emission images at discharging voltages 240 kV and 780 the attenuation carbon ions different magnetic fields are recorded using 24-framing camera for first time. results show that when voltage kV, light spots plasma generated by process randomly distributed over size brightness also distributed; if background Čerenkov radiation not taken into account,...