Design, simulation and experiment of a cusp electron beam for millimeter wave gyro-devices

The design, simulation and experiment of a thermionic cusp electron gun that is to be used for millimeter wave generation will be presented. A cusp gun uses a non-adiabatic magnetic field reversal to obtain azimuthal motion on an electron beam resulting in an annular shaped, axis-encircling beam. The cusp gun was designed to generate a beam of 1.5A at 40kV with an adjustable velocity ratio of up to 3.0. The beam had a simulated axial velocity spread of 7.4% and alpha spread of 10.1%. The beam had an averaged radius of 0.35mm and beam thickness of 0.05mm which is ideal to drive sub-mm wave gyro-devices under investigation

FINDING INTERNATIONAL CONTRACTING OPPORTUNITIES: AI EXTENSIONS TO EDI

Electronic Data Interchange (EDI) offers a telecommunications infrastructure for inter-business communications. This paper proposes a particular use of that infra-structure to aid firms in identifying contracting opportunities, particularly where international trade is involved. We focus on two aspects of this problem: navigating the legal procedures relating to such contracts and managing the multi-lingual communications

USSR Space Life Sciences Digest, Issue 18

This is the 18th issue of NASA's USSR Life Sciences Digest. It contains abstracts of 50 papers published in Russian language periodicals or presented at conferences and of 8 new Soviet monographs. Selected abstracts are illustrated with figures and tables from the original. A review of a recent Aviation Medicine Handbook is also included. The abstracts in this issue have been identified as relevant to 37 areas of space biology and medicine. These areas are: adaptation, aviation medicine, biological rhythms, biospherics, body fluids, cardiovascular and respiratory systems, cytology, developmental biology, endocrinology, enzymology, equipment and instrumentation, exobiology, gastrointestinal system, genetics, gravitational biology, group dynamics, habitability and environmental effects, hematology, human performance, immunology, life support systems, man-machine systems, mathematical modeling, metabolism, microbiology, musculoskeletal system, neurophysiology, nutrition, operational medicine, perception, personnel selection, psychology, radiobiology, reproductive biology, space biology and medicine, and space industrialization

Surgery on Nullhomologous Tori

By studying the example of smooth structures on CP^2#3(-CP^2) we illustrate how surgery on a single embedded nullhomologous torus can be utilized to change the symplectic structure, the Seiberg-Witten invariant, and hence the smooth structure on a 4-manifold

USSR Space Life Sciences Digest, issue 16

This is the sixteenth issue of NASA's USSR Life Sciences Digest. It contains abstracts of 57 papers published in Russian language periodicals or presented at conferences and of 2 new Soviet monographs. Selected abstracts are illustrated with figures and tables from the original. An additional feature is the review of a book concerned with metabolic response to the stress of space flight. The abstracts included in this issue are relevant to 33 areas of space biology and medicine. These areas are: adaptation, biological rhythms, bionics, biospherics, body fluids, botany, cardiovascular and respiratory systems, developmental biology, endocrinology, enzymology, exobiology, gastrointestinal system, genetics, gravitational biology, habitability and environmental effects, hematology, human performance, immunology, life support systems, man-machine systems, mathematical modeling, metabolism, microbiology, musculoskeletal system, neurophysiology, nutrition, operational medicine, perception, personnel selection, psychology, radiobiology, reproductive biology, and space biology

A cusp electron gun for millimeter wave gyrodevices

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

A cusp electron gun for millimeter wave gyro-devices

A thermionic cusp electron gun has been designed, numerically optimized and experimentally measured and is presented. A 40 kV, 1.5 A annular axis-encircling electron beam has been simulated to generate a beam with low velocity and alpha spreads. The electron gun performance has been verified through experiments. Based on the measured results further improvement and optimization of the cusp gun for high frequency operation were carried out and the results will be presented

Multi-mode coupling wave theory for helically corrugated waveguide

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

Simulation of a four-stage depressed collector for a W-band gyro-BWO

To improve the overall efficiency of the W-band gyrotron backward wave oscillator (gyro-BWO) currently being built in the University of Strathclyde, an energy recovery system using a four-stage depressed collector was simulated and designed. The spent beam information was exported from the simulation of the gyro-BWO using the 3D PIC code MAGIC. The geometry of the depressed collector was optimized using a genetic algorithm to achieve the optimum overall recovery efficiency for specific parameters of the spent beam. Secondary electron emissions were simulated to investigate the effects of the secondary electrons on the overall recovery efficiency and the backstreaming of the electrons from the collector region