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Electron Devices, IEEE Transactions on

Issue 1 • Date Jan. 1977

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Displaying Results 1 - 14 of 14
  • [Front cover and table of contents]

    Page(s): c1
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    Freely Available from IEEE
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  • A large-signal analysis of broad-band klystrons with design applications

    Page(s): 3 - 12
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    For the design of a high-performance broad-band klystron, an accurate large-signal analysis is made. By a one-dimensional analysis program using a disk model of the electron stream, the interaction between a bunched electron beam and the electric field in each cavity gap is studied, taking into consideration space-charge forces, relativistic effects, and electric field distributions in ungridded gaps; beam loading is included by an iterative method at each intermediate gap, and the energy exchange in the output gap is obtained from the change in kinetic energy. On the five-cavity UHF-TV klystron designed with this program and having a conversion efficiency of over 60 percent, the debunching effect of the electric field in intermediate cavity gaps and the behavior of vibrating electrons in the output gap are clarified. Calculated conversion efficiency is shown to agree well with measured efficiency over the pass-band. Additionally, by a two-dimensional analysis program, the effect of the cathode magnetic coefficient on the electron bunching is studied. View full abstract»

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  • Broad-band injected-beam crossed-field amplifiers

    Page(s): 13 - 21
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    The design and operation of injected-beam-crossed-field amplifiers, which provide efficient amplification over octave frequency bands with grid control in compact PM Focused format, are described. Dielectric supported meander lines, which are used to provide the low-dispersion and high-interaction impedance required to achieve octave bandwidth, are detailed. Relationships between space charge, gain factor, beam impedance, circuit loss, and circuit dimensions are derived for design optimization. An electron gun with a negative grid, which provides noise suppression, as well as a nonintercepting current control electrode, is shown to be effective in controlling the beam current continuously from zero to full operating value. Operating characteristics of production CFA's, providing 1 kW of average power in pulsed and CW operation and up to 5-kW peak pulsed power, are presented to illustrate the inherent multimode performance which can be achieved with low-voltage grid control. View full abstract»

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  • Starting in the cold cathode distributed emission crossed field amplifier

    Page(s): 22 - 26
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    The role of back bombarding electrons in the "starting" process of distributed emission crossed-field amplifiers is examined in this paper. Simple closed-form expressions are derived which show how the various parameters of the crossed-field amplifier affect the back bombardment potential and phase shift of the electrons in the initial (space-charge-free) current build-up region. A comparison of the results of this paper with a more accurate computer analysis is made for a specific case. The agreement between the two methods is shown to be excellent. Several curves are plotted which make it possible to easily find the back bombardment potentials and phase shifts for a wide range of tube parameters. View full abstract»

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  • A contribution to computer analysis of coupled-cavity traveling wave tubes

    Page(s): 27 - 31
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    A flexible accurate large-signal computer program has been developed for the design of coupled-cavity traveling wave tubes. The program is written for a TSS-360 time sharing system. The beam is described by a disk model and the slow wave structure by a sequence of cavities or cells. The computational approach is arranged so that each cavity may have different geometrical or electrical parameters than its neighbors. This allows the program user to simulate a tube of almost arbitrary complexity. Input and output couplers, severs, complicated velocity tapers, and other features peculiar to one or a few cavities may be modeled by a correct choice of input data. The beam-wave interaction is handled by a new approach in which the RF fields are expanded in solutions to the TM wave equation retaining all significant space harmonics. The program was used to perform a design study of the TWT developed for the CTS satellite. Good agreement was obtained between the predictions of the program and the measured performance of the flight tube. The internal check on power balance was satisfied within ±0.2 percent of input beam power. View full abstract»

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  • Analysis of spent beam refocusing to achieve optimum collector efficiency

    Page(s): 32 - 36
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    A reasonable criterion for evaluating the effectiveness of spent beam refocusing is the reduction of spent beam turbulence. The rms deviation of particle angles where the angles are calculated from the ratio of radial velocity to axial velocity is one measure of beam turbulence. It is demonstrated that the angular deviation can be reduced by almost half in some magnetic field configurations. Experimental evidence indicates that beam processing of this type is most likely to yield an optimum collector efficiency. View full abstract»

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  • Small-size 81- to 83.5-percent efficient 2- and 4-stage depressed collectors for octave-bandwidth high-performance TWT's

    Page(s): 36 - 44
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    In a joint USAF-NASA Program, Lewis Research Center is carrying out an efficiency improvement program on traveling wave tubes (TWT) for use in electronic counter measures (ECM) by applying multistage depressed collector (MDC) and spent beam refocusing techniques developed at Lewis. In the analytic part of the effort, three-dimensional electron trajectories are computed throughout the TWT. Trajectory computation continues through the spent beam refocuser and the depressed collector. Collector efficiency, collector losses, and overall efficiency are identified and computed. On the experimental side, tube performance is evaluated first without the MDC; then, the spent beam is analyzed for symmetry, circularity, and velocity spread. Finally, the MDC is attached and its performance optimized and evaluated. The three-dimensional theory, for ideal tubes, predicts a MDC-efficiency, at mid-band, of 81 percent for a 2-stage MDC with symmetric, circular, and optimally refocused beams and 85.5 percent for a 4-stage MDC. Experimental results to date have yielded MDC efficiencies of a minimum of 81 and 83 percent for a 2- and 4-stage MDC, respectively, across a one-octave bandwidth of a 4.8 to 9.6 GHz 330-to-550-W TWT. View full abstract»

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  • A novel electrostatic-focusing depressed collector for linear beam tubes

    Page(s): 45 - 52
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    In a theoretical study, various types of retarding electrostatic fields are compared with respect to their usefulness in a depressed collector. Without space charge, fields having focusing properties lead to higher collector efficiencies ηcollthan defocusing fields. For a special case, the hyperbolic field, ηcollis given as a function of the angular beam spread, beam diameter, and initial beam energy. ηcollincreases with 1) decreasing angular beam spread, 2) increasing ratio of collector size to beam diameter, 3) increasing initial beam energy, and 4) the number of collector stages. Experimentally, a 3-stage collector of the hyperbolic field type was studied in connection with a PPM-focused high-power Dual Mode TWT, having a pulse-up ratio of 8 dB. At 50-, 75,, and 100- percent depression, the tube efficiency was 26 percent in the low-power mode and 34 percent in the high-power mode, corresponding to collector efficiencies of 76 and 71 percent, respectively. View full abstract»

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  • A 2-kW average power X-band receiver protector

    Page(s): 53 - 55
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    A 2-kW average power receiver protector with a 5000-h operating life has been developed. The design is of the gas plasma diode hybrid type which heretofore could provide only one-tenth the power handling for equivalent operating life. Predicted life is based on experimentally obtained molecular sorption coefficients performed at 2-kW average power in X band. The device has been developed for use as a receiver protector in a high-resolution radar to be used at Lincoln Laboratory. This radar will transmit 200-kW average power at X band and consequently requires a high average power receiver protector. View full abstract»

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  • Use of auger spectroscopy in the evaluation of thermionic cathodes

    Page(s): 56 - 61
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    The ability of Auger spectroscopy to identify chemical species existing on a surface has been used to evaluate the properties of "good" and "poor" impregnated tungsten cathodes used in high-power microwave wave tubes. The surfaces of "good" and "poor" cathodes were studied by means of Auger spectroscopy and work function measurements and the results interpreted to analyze failure modes in cathodes removed from TWT's because of poor emission characteristics. Most of the poor cathodes evaluated in this program were obtained from fabricated electron guns that had been employed and discarded from the 200-W TWT tubes developed for the Communication Technology Satellite (CTS) program. The results of these measurements have shown there are at least two types of failure modes that one observes with poor cathodes. They are 1) chemical contamination of the cathode surface and 2) low partial layer barium coverage of the cathode surface. View full abstract»

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  • The role of ceramic voids and fracture propagation in shelf life failure of tubes

    Page(s): 62 - 66
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    Small tubes having an internal volume of 0.1 cm3were found to become gassy during shelf life and subsequently to arc when turned on. Quadrupole mass analysis and Auger electron spectroscopy were used to identify internal gasses and deposits on electrodes of gassy tubes. Gasses released during ceramic fracture propagation were also studied. The results indicate that for the tubes investigated, the predominant failure mechanism involved the growth of ceramic micro cracks which are connected to the interior of the tube. As the crack propagates, it releases N2which was trapped in the voids of the ceramic. Cracks extending only a fraction of the ceramic wall thickness are sufficient to liberate enough N2into the tube to correspond to a pressure of 10-3torr, which will result in an arc during turn-on. View full abstract»

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  • Electron trajectories in the PPM-focused coupled-cavity TWT

    Page(s): 67 - 68
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    Trajectories of electrons in a coupled-cavity TWT with ppm focusing are plotted in both r-z and x-y views. Plots are given for magnetic fields from 1.0 to 1.9 times the Brillouin field, and for small signal and saturated RF conditions. It is shown that a suitably programmed field can control the beam entry problem and minimize the RF debunching, while significantly reducing the beam exit angle. The computer program is briefly described. View full abstract»

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  • [Back cover]

    Page(s): c4
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    Freely Available from IEEE

Aims & Scope

IEEE Transactions on Electron Devices publishes original and significant contributions relating to the theory, modeling, design, performance and reliability of electron and ion integrated circuit devices and interconnects.

 

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Meet Our Editors

Acting Editor-in-Chief

Dr. Paul K.-L. Yu

Dept. ECE
University of California San Diego