Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Recent research and development has been incredibly successful at advancing the capabilities for vacuum electronic device (VED) sources of powerful terahertz (THz) and near-THz coherent radiation, both CW or average and pulsed. Currently, the VED source portfolio covers over 12 orders of magnitude in power (mW-to-GW) and two orders of magnitude in frequency (from ; 10 THz). Further advances are still possible and anticipated. They will be enabled by improved understanding of fundamental beam-wave interactions, electromagnetic mode competition and mode control, along with research and development of new materials, fabrication methods, cathodes, electron beam alignment and focusing, magnet technologies, THz metrology and advanced, broadband output radiation coupling techniques.

Vacuum Electronic High Power Terahertz Sources

The electron cyclotron maser (ECM) is based on a stimulated cyclotron emission process involving energetic electrons in gyrational motion. It constitutes a cornerstone of relativistic electronics, a discipline that has emerged from our understanding and utilization of relativistic effects for the generation of coherent radiation from free electrons. Over a span of four decades, the ECM has undergone a remarkably successful evolution from basic research to device implementation while continuously being enriched by new physical insights. By delivering unprecedented power levels, ECM-based devices have occupied a unique position in the millimeter and submillimeter regions of the electromagnetic spectrum, and find use in numerous applications such as fusion plasma heating, advanced radars, industrial processing, materials characterization, particle acceleration, and tracking of space objects. This article presents a comprehensive review of the fundamental principles of the ECM and their embodiment in practical devices.

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The electron cyclotron maser

This article reviews the state-of-the-art in high-power microwave source research. It begins with a discussion of the concepts involved in coherent microwave generation. The main varieties of microwave tubes are classified into three groups, according to the fundamental radiation mechanism involved: Cherenkov, transition, or bremsstrahlung radiation. This is followed by a brief discussion of some of the technical fundamentals of high-power microwave sources, including power supplies and electron guns. Finally, the history and recent developments of both high-peak power and high-average power sources are reviewed in the context of four main areas of application: (1) plasma resonance heating and current drive; (2) rf acceleration of charged particles; (3) radar and communications systems; and (4) high-peak power sources for weapons-effect simulation and exploratory development.

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Review of high-power microwave source research

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Plasma Physics and Controlled Fusion Conference: Focussing on Tokamak Research

In the analysis of propagation of wave beams in quasi-optical transmission lines, the loss rate and transformation of modes by various elements of the transmission line are of great importance. The effects occurring when a spatially bounded, obliquely incident wave beam is reflected from a Bragg resonator being a periodic, plane-layered medium with varied dielectric permittivity are considered. Such a reflector can be used as a frequency-selective element of the transmission line. Since the reflection coefficient of a plane wave from the Bragg reflector depends on its incidence angle, there occurs a transformation of the reflected beam. Analytical expressions for the beam displacement, the angle of deflection of the beam from the mirror reflection direction, and the wavefront curvature variation have been obtained. The influence of the mentioned effects on characteristics of the reflected wave beam in the main band of the Bragg reflector is numerically analyzed. The possibility of compensation for these distortions is considered.

Improving the Efficiency of Quasi-Optical Bragg Reflectors

This paper is devoted to theoretical and experimental investigation of high power microwave Chercnkov oscillators using of high current nanosecond electron beams. The influence of non synchronous waves and additional (non Cherenkov) resonance on the process of microwave generation in 3 cm relativistic BWO are discussed. Experimentaldata presented in this paper show that the efficiency of 3 cm relativistic BWO can achieve 40% and pulsed microwave power - 500 MW. The enhancement of microwave power and efficiency of microwave generation was reached by creating of the non uniformity of the synchronous wave phase velocity and that of the coupling coefficient between the electrons and the electromagnetic wave. We experimentally StUdied the oversize Cherenkov oscillators in mm wavelength. One of them was 8 mm 120 MW orotron with TM13-mode of the circular waveguide. The another one wastwo stage two electron beams 8 mm Chererikov oscillator. The maximum of microwave power in this experiment was600 MW, pulse duration was 10-15 ns. All of experiments were carried out by high current electron accelerators of typeSINUS. The performance parameters of our accelerators are the following: electron energy from 100 to 2000 keV, beamcurrent from 1 to 20 kA, pulse duration from 5

High-power microwave Cherenkov oscillators with high-current relativistic electron beams

Using the methods of synthesis of waveguide components developed by the authors, a number of highly efficient and compact mode converters for smooth and corrugated oversized circular waveguides were calculated High efficiency of the converters was proved in experiment

Highly efficient mode converters for smooth and corrugated circular waveguide

A brief summary of current developments in Russia of megawatt power gyrotrons is presented. The gyrotron developed are applied in experiments at several modern tokamaks. New demands to gyrotron parameters and possible ways to reach them are discussed.

Development of Megawatt Gyrotrons in IAP/GYCOM

We present the results of first experiments on generation of trains of sub-nanosecond Ka-band pulses in the electron oscillator consisting of a helical-waveguide gyro-TWT and a saturable absorber based on cyclotron resonance interaction of radiation with initially rectilinear electron beam. The process of pulse formation is associated with the effect of passive mode locking which is well known in laser physics but has not yet been employed in high-power microwave electronics. In good agreement with the theoretical predictions, periodical trains of coherent (in-phase) 0.5 ns pulses with peak power of 100 kW and repetition period of 2.5 ns were measured.

G. G. Denisov

Papers

Improving the Efficiency of Quasi-Optical Bragg Reflectors

High-power microwave Cherenkov oscillators with high-current relativistic electron beams

Highly efficient mode converters for smooth and corrugated circular waveguide

Development of Megawatt Gyrotrons in IAP/GYCOM

Ka-Band Ultra-Short Pulse Oscillator with Helical-Waveguide Gyro-TWT and Cyclotron Resonance Absorber in the Feedback Loop