First bandwidth measurements of a novel gyrotron amplifier are presented. The coupling between the second harmonic cyclotron mode gyrating electron beam and radiation field occurred in region near infinite phase velocity over broad by using cylindrical waveguide with helical corrugation on its internal surface. With energy 185 keV, achieved maximum output power 1.1 MW, saturated gain 37 dB, linear 47 8.4 to 10.4 GHz ( 21% relative bandwidth), an efficiency 29%, good agreement theory.

A new microwave system in the form of a cylindrical waveguide with helical corrugation inner surface is proposed for gyrotron traveling wave tube (gyro-TWT). The radically changes dispersion region small axial numbers. This allows significant reduction sensitivity amplifier to electron velocity spread and an increase its frequency bandwidth. An $X\ensuremath{-}\mathrm{band}$ gyro-TWT operating at second cyclotron harmonic 200-keV, 25-A beam produced output power 1 MW, corresponding gain 23...

A helical corrugation of the inner surface an oversized cylindrical waveguide provides, for certain parameters, almost constant value group velocity and close to zero longitudinal wavenumber eigenwave a very broad frequency band. The use such as operating section gyrotron traveling wave tube (gyro-TWT) allows significant widening its bandwidth increase in efficiency at large particle spreads. In this paper, new concept is confirmed by theoretical analysis "cold" measurements dispersion....

The experimental results of a thermionic cusp electron gun, to drive millimeter and submillimeter wave harmonic gyrodevices, are reported in this paper. Using “smooth” magnetic field reversal formed by two coils gun generated an annular-shaped, axis-encircling beam with 1.5 A current, adjustable velocity ratio α up 1.56 at voltage 40 kV. cross-sectional shape transported current were measured witness plate technique Faraday cup, respectively. These found be excellent agreement the simulated...

Experimental results are presented of a broadband, high power, gyrotron traveling wave amplifier (gyro-TWA) operating in the (75-110)-GHz frequency band and based on helically corrugated interaction region. The second harmonic cyclotron mode 55-keV, 1.5-A, axis-encircling electron beam is used to resonantly interact with TE_{21}-like eigenwave achieving broadband amplification. gyro-TWA demonstrates 3-dB gain bandwidth at least 5.5 GHz experimental measurement 9 predicted for wideband drive...

This paper presents for the generation of a small size high current density pseudospark (PS) electron beam frequency (0.2 THz) Backward Wave Oscillator (BWO) through Doppler up-shift plasma frequency. An ∼1 mm diameter carrying up to 10 A and 108 m−2, with sweeping voltage 42 25 kV pulse duration ns, was generated from PS discharge. propagated rippled-wall slow wave structure BWO beam-wave interaction region in environment without need guiding magnetic field. Plasma assisted resulted...

Experimental operation of a gyrotron traveling wave amplifier with helically corrugated waveguide using thermionic cathode electron gun is presented. The coupling between the second harmonic cyclotron mode gyrating beam and radiation occurred in region near infinite phase velocity over broad frequency band. With an axis-encircling pitch factor ∼1.2, energy 185keV, current 6.0A, achieved output power 220kW, saturated gain 24dB, bandwidth 8.4to10.4GHz, interaction efficiency 20%.

Helically corrugated waveguide has been used in various applications such as gyro-backward wave oscillators, gyro-traveling amplifier and microwave pulse compressor. A fast prediction of the dispersion characteristic operating eigenwave is very important when designing a helically waveguide. In this paper, multi-mode coupling equations were developed based on perturbation method. This method was then to analyze five-fold for X-band compression. The calculated result from analysis found be...

We demonstrate both theoretically and experimentally the possibility of correlating phase a Cherenkov superradiance (SR) pulse to sharp edge current pulse, when spontaneous emission electron bunch serves as seed for SR processes. By division driving voltage across several parallel channels equipped with independent cathodes we can synchronize sources arrange two-dimensional array. In experiments carried out, coherent summation radiation from four 8-mm wavelength band generators peak power...

A W-band extended interaction oscillator (EIO) driven by a pseudospark-sourced sheet electron beam (PS-SEB) is demonstrated in this letter. The idea of combining the advantages (high current density), geometry (large cross-sectional area), and ladderlike slow wave structure (high-gain per unit length) to generate powerful millimeter-wave radiation was experimentally verified. PS-SEB based EIO produced ~1.2-kW peak output power, an increase six times measured power from on pencil beam. Such...

Intense microwave pulses (several hundreds of kilowatts) ultrashort duration (less than 0.5 ns) were obtained from an ensemble electrons rotating in a uniform magnetic field. The comparison with theoretical simulations proves that this emission can be interpreted as cyclotron superradiance. maximum radiation power was achieved under group synchronism conditions, when the electron bunch translational velocity coincides wave propagating waveguide.

A helically corrugated waveguide was used for a gyrotron backward-wave oscillator (gyro-BWO) experiment. thermionic cathode to produce an electron beam of 90-215 keV in energy, 2-3 current, and pitch alpha up 1.6. The achieved high-efficiency frequency-tunable operation. At fixed voltage 185 kV current 2 A, the output frequency tuned by adjusting magnetic field interaction cavity. maximum power 62 kW 3-dB frequency-tuning band 8.0-9.5 GHz (17% relative tuning range) with electronic...

A pseudospark (PS) discharge has been shown to be a promising source of high brightness, intensity electron beam pulses. PS-sourced two phases, an initial hollow cathode phase (HCP) followed by conductive (CP) beam. In our experiments, 22 kV, 50 HCP brightness 109–10 m−2 rad−2 200 V, CP 1011–12 were measured. Experiments have conducted with the application in Cherenkov interaction no input seed wave and post-acceleration this paper, new experiment from 20 kW, 35 GHz pulsed magnetron designed...

The generation of an annular-shaped axis-encircling electron beam using a smooth magnetic cusp was studied through numerical simulations and experiments for harmonic operation gyrodevice. Two coils were used to form located just downstream from the velvet cathode accelerator diode. An current 34 A voltage 130 kV with adjustable velocity ratio α up 1.2 fully transported uniform field region drive gyrotron traveling wave amplifier into saturation.

A gyrotron backward wave oscillator (gyro-BWO) with a helically corrugated interaction waveguide demonstrated its potential as powerful microwave source high efficiency and wide frequency tuning range. This letter presents the theory describing dispersion properties of such linear beam-wave interaction. Numerical simulation results using PIC code MAGIC were found to be in excellent agreement output measured from gyro-BWO experiment.

Experimental studies of the production and propagation an electron beam from a multigap pseudospark discharge are presented. From three-gap pseudospark, up to 680 A was measured at anode applied dc voltage 23 kV. This can propagate downstream as far 20 cm in gaseous environment with no guiding magnetic field, which confirms that transport based on neutralization space charge due ionization gas molecules by itself. The is very small size 1–3 mm diameter ideal drive high frequency radiation....

A two-dimensional (2D), cylindrical, periodic surface lattice (PSL) forming a field cavity is considered. The created by introducing 2D perturbations on the inner of cylindrical waveguide. PSL facilitates resonant coupling and near cutoff volume fields, leading to formation high-$Q$ eigenmode. eigenmode described investigated using modal approach, considering model waveguide partially loaded with metadielectric. By PSL-based cavity, concept high-power, 0.2-THz Cherenkov source developed. It...

The study of a planar G-band extended interaction oscillator (EIO) driven by pseudospark-sourced (PS) sheet electron beam is presented. This enables the advantages circuit combined with merits PS beam, including large cross section, high current density and fact that does not require use an external focusing magnetic field. Beam-wave simulations for this EIO predicted peak output power 2.1 kW at ~0.2 THz. Investigations indicate has better tube performance higher radiation compared pencil EIO.

Experimental results of the observation coherent stimulated radiation from subnanosecond electron bunches moving through a periodic waveguide and interacting with backward propagating wave are presented. The microwave pulses in Ka W bands were generated repetition frequencies up to 25 Hz. mechanism pulse generation was associated self-bunching, mutual influence different parts due slippage respect electrons; this can be interpreted as superradiance. illumination panel neon bulbs resulted...

A new method to generate ultrahigh-power microwave pulses compatible with mildly relativistic electron sources is proposed. This involves a novel compressor in the form of metal helically corrugated waveguide, which can enhance power frequency-modulated nanosecond up multigigawatt level. The results proof-of-principle experiments at kilowatt levels are good agreement theory.

Helically corrugated waveguides have recently been studied for use in various applications such as interaction regions gyrotron traveling-wave tubes and backward-wave oscillators a dispersive medium passive microwave pulse compression. The paper presents summary of methods that can be used analysis the wave dispersion waveguides. results obtained from an analytical approach, simulations with three-dimensional numerical code MAGIC, cold measurements are analyzed compared.

The first operation of a coaxial free-electron maser (FEM) based on two-dimensional (2D) distributed feedback has been recently observed. Analytical and numerical modeling, as well measurements, microwave radiation generated by FEM with cavity defined structures 2D periodic perturbation the inner surfaces outer conductor were carried out. two-mirror was formed two separated central smooth section waveguide. driven large diameter (7 cm), high-current (500 A), annular electron beam energy 475...

A novel thermionic cusp electron gun operating in the temperature-limited regime that produces a large-orbit beam through nonadiabatic magnetic-field reversal was designed, analyzed, and optimized to give an electron-beam ideal for driving gyro-devices, particularly millimeter-to-submillimeter-wavelength range due its small cross-sectional size. The annular-shaped axis-encircling had current of 1.5 at acceleration potential 40 kV, tunable velocity ratio alpha (= v <sub...