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...

Even after 50 years of development, narrowband high-power microwave (HPM) source technologies remain the focus much research due to intense interest in innovative applications HPMs fields such as directed energy, space propulsion, and radar. A few decades ago, main aim investigations this field was enhance output power a single HPM tens or hundreds gigawatts, but goal has proven difficult physical limitations. Therefore, recent into sources focused on five targets: phase locking combination,...

Photoconductivity in individual semiconducting single-wall carbon nanotubes was investigated using a confocal scanning optical microscope. The magnitude of the photocurrent found to increase linearly with laser intensity, and be maximum for parallel orientation between light polarization tube axis. Larger currents were obtained upon illuminating tubes at 514.5 nm comparison those 647.1 nm, consistent having resonant absorption energy former wavelength. Moreover, determination photoresponse...

The initial experimental results of an L-band coaxial relativistic backward wave oscillator with mechanical frequency tunability are presented. key effects the inner-conductor contributing to investigated theoretically and experimentally. In experiments, microwave 1.58 GHz is radiated when radius 1.5 cm. Meanwhile, S-band 2.31 generated after removing inner-conductor. addition, tuning within 4% realized by mechanically altering at a half power level.

Electrochemical coating of individual single‐walled carbon nanotubes (SWCNTs) with thin films obtained via oxidative coupling an amine or reductive aromatic diazonium salt is reported. The same SWCNTs have been characterized before and after modification by electrical transport measurements confocal Raman spectroscopy (see Figure, electrode structure white, background dark blue, light blue to red).

The location of chemical defects in single-walled carbon nanotubes (SWCNTs) can easily be identified as is presented this communication. method relies on the formation Se nanoparticles via site-selective oxidation H2Se, which works under soft conditions at room temperature and able to reveal even individual tubes. Figure depicts an AFM image SWCNTs after H2Se exposure for 100 s.

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...

A compact mode converter, which is capable of converting a TM01 into circularly polarized TE11 mode, was developed and experimentally studied with high-power microwaves. The consisting two turnstile junctions, very short along the wave propagation direction, therefore suitable for designing axially aligned microwave radiation systems. In this paper, principle converter working at 1.75 GHz demonstrated, as well experimental results. simulation results are in good agreement. At center...

We present thermal and electron micrographs of an incandescent lamp constructed from a multiwalled carbon nanotube, correlate the subwavelength optical information with underlying nanoscopic structure. Remarkably, heat equation Planck's law together give precise, quantitative description light intensity as function input power, even though nanotube's small size places it outside thermodynamic limit.

The experimental results of the tunable load-limited magnetically insulated transmission line oscillator (TLMILO) are presented and discussed in this paper. In experiments, microwave frequency TLMILO can be changed arbitrarily range 1.337-1.760 GHz by changing tuner, tuning bandwidth is 13.6%. show that normal relative error frequencies between measured result simulation not more than 1.6%, mechanism does affect MILO's operation, maximum power efficiency 15.2%. demonstrate feasibility TLMILO.

The improved magnetically insulated transmission line oscillator (MILO) is a gigawatt-class L-band high power microwave tube. It has allowed us to generate 3.1 GW pulse of 40 ns duration in the single-pulse operation and 500 MW 25 repetition rate operation. However, because severe impedance mismatch, conversion efficiency only about 4% In order eliminate mismatch obtain repetitive long-pulse high-power (HPM), series experiments are carried out recent progress presented this paper. operation,...

The photoluminescence spectrum of melt-grown GaSe single crystals was investigated with a confocal Raman microscope equipped HeNe laser. Three luminescence bands different intensity were observed, which are mainly located to the blue laser line. signals show quadratic dependence on excitation intensity. effect is interpreted as second-harmonic generation in strongly optically nonlinear material followed by electrons into conduction band and emission from direct-gap Wannier excitons. relative...

A mode-transducing antenna composed of a coaxial plate-inserted mode converter and compact conical horn was presented. The transforms the TEM into TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> firstly then radiates it from horn. It has virtues compactness, high aperture efficiency, boresight peak, low sidelobe level. An for 1.76 GHz magnetically insulated transmission-line oscillator (MILO) designed with length 60 cm an radius 23.5...

A compact relativistic magnetron with axial microwave radiation is experimentally investigated. Under the modified magnetic field distribution, only connecting a special horn antenna in direction, can stably radiate high power and efficiency microwaves. The total length of device ∼0.3 m, volume ∼0.014m3. In such working condition that applied voltage 539 kV ∼0.38 T, output ∼1.24 GW. Correspondingly, about 34.1%. radiating frequency 2.35GHz, which agreement π mode theoretical expectation.

A dielectric-filled magnetically insulated transmission line oscillator (DFMILO) is presented in this paper, which introduces a low-loss dielectric to fill its resonant cavities and thus improves technical performances. The fundamental mode frequency of the DFMILO derived dispersion curve analyzed. In simulation, high-power microwave generated from with peak power 3.1 GW, 1.467 GHz, conversion efficiency 14.0% when voltage 455 kV current 48.7 kA. However, relevant unfilled MILO only 8.5%....

This paper provides a review of the compact intense electron-beam accelerators (IEBAs) based on liquid pulse forming lines (PFLs) that have been developed at National University Defense Technology (NUDT) in China. The history and roadmap IEBAs used to drive high-power microwave (HPM) devices NUDT are reviewed. properties both de-ionized water glycerin as energy storage media presented. Research into breakdown dielectrics desire maximize resulted invention several coaxial PFLs with different...

A tunable magnetically insulated transmission line oscillator (MILO) is put forward and simulated. When the MILO driven by a 430 kV, 40.6 kA electron beam, high-power microwave generated with peak output power of 3.0 GW frequency 1.51 GHz, relevant conversion efficiency 17.2%. The 3-dB range (the relative above half power) 2.25–0.825 GHz when outer radius slow-wave structure (SWS) vanes ranges from 77 mm to 155 mm, tuning bandwidth 92%, which sufficient for aim large-scale high output.

A magnetically insulated transmission line oscillator (MILO) is a crossed-field device designed specifically to generate microwave power at the gigawatt level, which major hotspot in field of high-power microwaves (HPM) research present. It one thrust for MILO development improve conversion efficiency. In order efficiency MILO, complex presented and investigated theoretically numerically, comprises MILO-1 MILO-2. The MILO-2 used as load MILO-1. theoretical analyses show that maximum has an...

The fundamental mode frequency of A6 magnetron is investigated theoretically by the equivalent circuit method, and an exact theoretical formula as a function structure dimensions derived. results are compared with simulation experimental results, relative errors, which calculated according to or frequencies, less than 3%. So validity verified. In addition, this approach can also be used in other configurations but some changes need made specific structures.