Recent experimental results of three kinds long-pulse high-power microwave (HPM) sources operating in S-, C-, and X-bands are reported. The difficulties producing a HPM for the O-type Cerenkov source were analyzed theoretically. In S- C-bands, single-mode relativistic backward-wave oscillators designed to achieve outputs; X-band, because its shorter wavelength, an with overmoded slow-wave systems was increase power capacity. experiments, driven by repetitive accelerator, both C-band...

The efficient operation of high-power microwave (HPM) sources using slow-wave structures (SWSs) in low magnetic field has been an attractive aim pursued by HPM researchers. This paper presents the latest experimental results X-band oversized SWS source operating at guiding with both power and efficiency enhancements. Driven electron accelerator diode voltages 450-900 kV, generator operated output ranging from 0.5 to 3 GW being kept about 25%. optimized was 0.5-0.75 T range, depending on...

A radial line slot antenna (RLSA) is a nonresonant multimode waveguide slotted array. To improve the power handing capacity, we design slow wave structure which replaces traditional dielectric sheet. At same time, of radiator unit redesigned and optimised. This high-power microwave (HPM) RLSA fed from double-layered to realize directional radiation microwave. However, slots spirally arrayed for circular polarization give rise serious reflection in higher order modes, disturbs normal...

In order to increase the power conversion efficiency of a magnetically insulated line oscillator (MILO), an axially extracted virtual cathode (VCO) is introduced utilize load current in MILO, so it called MILO-VCO. this device, MILO and VCO are operated synchronously generate high-power microwaves. The MILO-VCO investigated detail with particle-in-cell (PIC) methods (KARAT code). simulation, diode voltage 640 kV 50 kA. total peak 5.22 GW corresponding 16.3%. MILO-VCO, 3.91 its frequency 1.76...

An X-band magnetically insulated transmission line oscillator has been investigated theoretically and experimentally in our laboratory. However, severe pulse shortening electrode erosion are observed the experiments. The theoretical analyses show that anode plasma formation load region is essential reason for erosion. In order to eliminate or at least minimize region, an improved beam dump presented. can be eliminated minimized dump.

The magnetically insulated line oscillator (MILO) is an attractive high-power microwave source. It a compact lightweight gigawatt-class coaxial crossed field device that needs no externally applied magnetic to insulate electron flow in slow-wave structure. An improved MILO model has been presented by Fan, Yuan and Zhong. A novel beam dump, one-cavity RF choke section, mode-transducing antenna are introduced into the MILO. In simulation, of TEM mode generated with peak power 4.2 GW, frequency...

Magnetically insulated line oscillator (MILO) is a gigawatt-class high-power microwave source whose behavior has been investigated experimentally and numerically. This paper presents an improved MILO model. A novel beam dump, one-cavity RF choke section mode-transducing antenna are introduced into the MILO. The in detail with particle-in-cell method (KARAT code). In simulation, of transmission electron microscopy (TEM) mode generated peak power 4.2 GW, frequency 1.76 GHz, conversion...

The improved magnetically insulated transmission line oscillator (MILO) is a gigawatt-class L-band high power microwave tube driven by 550 kV, 57 kA, 50 ns electron beam. It has allowed us to generate 2.4 GW pulse of 22 duration. recent progress the MILO presented in this paper. First, field shaper cathode introduced into avoid flares triple point region. experimental results show that are avoided, so lifetime velvet longer than taper cathode. Furthermore, shot-to-shot reproducibility better...

In order to investigate the performances of repetition rate (rep-rate) operation an improved magnetically insulated transmission line oscillator (MILO), a series experiments are carried out on MILO device, which is driven by 40Ω, 50ns rep-rate pulser, TORCH-01. Polymer velvet and graphite cathodes tested, respectively, in experiments, whose diameters lengths same. The results experimental comparison between them presented paper. Both tested at electric field strengths about 300kV∕cm. applied...

A slow wave type gigawatt millimeter generator is proposed in this paper. In order to increase power capacity, overmoded structures (SWSs) with larger diameter have been used. Taking advantage of the “surface wave” property SWSs, TM01 mode can be selected operating mode. Calculations also carried out choose a proper low magnetic field strength, and it agrees particle cell (PIC) simulations. Main structure parameters device are optimized by PIC typical simulation result that, at beam 600 keV...

Long-pulse operation of relativistic backward-wave oscillators (RBWOs) is seriously handicapped by pulseshortening phenomenon. Explosive emission plasma formed on the surface slow-wave structures (SWSs) due to RF breakdown considered be predominant cause pulse shortening in RBWOs. Utilizing overmoded SWSs with large diameter effective for decreasing field strength and possibility breakdown. However, multiple modes may output simultaneously In this paper, both power capacity mode purity an...

A compact concentric array radial line slot antenna (CA-RLSA) operating at K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">u</sub> -band for high-power microwave (HPM) application is proposed in this paper. The efficiency of HPM-RLSA becomes lower as the aperture size reduces due to rotational asymmetry illumination. HPM-CA-RLSA was designed overcome difficulty with notable power handing capacity. It fed by circularly polarized TE11 coaxial...

Abstract The radio-frequency breakdown due to ultrahigh electric field strength essentially limits power handling capability of an individual high microwave (HPM) generator and this issue becomes more challenging for frequency bands. Coherent combining therefore provides alternative approach achieve equivalent peak the order ∼100 GW, which consequently opportunities explore related physics at extremes. triaxial klystron amplifier (TKA) is a promising candidate coherent combing in bands owing...

Triaxial klystron amplifier (TKA) is prom- ising for coherent power combining of high-power microwaves (HPMs) in high-frequency bands. In this letter, we present an improved X-band TKA to generate gigawatt long-pulse HPM radiations. By increasing the intrinsic quality factor input cavity, seed microwave loss reduced significantly. The beam loaded cavity increased enhance gap voltage and, moreover, strengthen electron modulation. addition, a double-gap output designed on one hand increase...

A compact and modular pulse forming network (PFN)-Marx generator with output parameters of 5 GW, 500 kV, 30 Hz repetition is designed constructed to produce intense electron beams for the purpose high-power microwave (HPM) generation in paper. The PFN-Marx composed by 22 stages PFN modules, each module formed three mica capacitors (6 nF/50 kV) connected parallel. Benefiting from utilization high energy density a mini-trigger source integrated into magnetic transformer switch, compactness...

In the X-band relativistic klystron oscillator, mode hopping phenomena in output microwave caused by low-order asymmetric TE11 competition are observed. Based on theoretical and simulation analyses of electron conductance external quality factors main TM013 TM113 mode, it is found that electronic conductivity both negative, their close, which cause competition. particle simulations, altering a pre-reflection cavity position cathode block, reflection coefficient increased, thereby enhancing...

A new diketopiperazine, spirotryprostatin C (1), as well nine known compounds (2-10), were isolated from the fermentation broth of karst cave derived fungus Cephalotrichum sp. RD-ZLM03. Their structures determined based on spectroscopic and X-ray diffraction analysis. Compounds 2, 4, 5, 6, 8, 9, 10 showed significant proangiogenic activities at concentration 25 μM in zebrafish model.

A 1.2-GHz magnetically insulated transmission line oscillator (MILO) is investigated numerically and experimentally in this paper. Simulation optimization performed with the particle-in-cell code KARAT. When diode voltage current are 680 kV 53 kA, output microwave power 4.15 GW, frequency 1.169 GHz, efficiency 11.5%. In order to radiate a boresight peak pattern, TEM-TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode-converting...

An overmoded slow wave type Ka band generator is investigated experimentally to produce high power millimeter waves in this paper. The experiments were carried out at the TORCH-01 accelerator. produced microwave frequency was measured by dispersive line method, and estimated integrating over radiation pattern far field. With relatively low guiding magnetic field of 0.8 T diode voltage beam current 590 kV 5.2 kA, respectively, a 33.56 GHz with an output 320 MW generated, mode quasi-TM01 mode.

The mode selection of a low guiding magnetic field relativistic Cherenkov generator based on coaxial combined periodic double-corrugation slow-wave structure (CPD-SWS) is studied. Owing to the flexible combination different periods CPD-SWS, electric distribution can be modified and coupling impedance specific enhanced, thus expected selected. research results indicate that quasi-TEM selected by adjusting depth outer inner corrugations CPD-SWS. Moreover, TM01 length corrugation Furthermore,...

A Ku-band phase-locked coaxial relativistic Cherenkov generator with a low guiding magnetic field is presented. Owing to the use of combined periodic double-corrugation slow-wave structure, quasi-TEM mode exhibits strong axial electric at center beam tunnel. As result, electron can achieve effective beam–wave interaction without proximity SWS surfaces, allowing larger envelope and, therefore, reducing demand for fields. Two single-gap cascaded pre-modulation cavities are used reduce injected...

Abstract An electron-beam accelerator based on spiral water pulse forming line which consists of a primary storage capacitor system, an air core strip transformer, dielectric, and field-emission diode, is described. The experimental results showed that the diode voltage more than 500 kV, electron beam current about 24 kA, duration 200 ns. main parameters were calculated theoretically. distributions for electrical field in obtained by simulations. In addition, process charging was simulated...

This paper presents both numerical and experimental studies of a repetitive S-band long-pulse relativistic backward-wave oscillator. The dispersion relation curve the main slow-wave structure is given by calculation. Experimental results show that 1 GW microwaves with pulse duration about 100 ns (full width half magnitude) under 10 Hz operation mode are obtained. microwave frequency 3.6 GHz dominant TM(01), power conversion efficiency 20%. single energy J. in good agreement simulation ones....