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Electron Devices, IEEE Transactions on

Issue 1 • Date Jan 2001

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Displaying Results 1 - 25 of 29
  • Silicide application on gated single-crystal, polycrystalline and amorphous silicon FEAs. II. Co silicide

    Publication Year: 2001 , Page(s): 155 - 160
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB)  

    For pt. I see ibid., vol.48, no.1, p.149-54 (Jan. 2001). For enhancement and stabilization of electron emission, Co silicides were formed from Co, Co/Ti and Ti/Co layers on silicon FEAs. Since Ti prevents oxygen adsorption on the Co film during silicidation, uniform and smooth Co silicide layers can be obtained by depositing Co first and then Ti on silicon tips, followed by rapid annealing. Among Co silicide FEAs, Co silicide formed from Ti/Co bi-layers shows the lowest leakage current, the highest failure voltage over 152 V and the largest anode current over 1 mA at the gate voltage of 150 V. Compared with silicon field emitters, the silicide FEAs formed from Ti/Co layers exhibited a significant improvement in maximum emission current, emission current fluctuation and stability, and failure voltage View full abstract»

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  • In-situ vacuum-sealed lateral FEAs with low turn-on voltage and high transconductance

    Publication Year: 2001 , Page(s): 161 - 165
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB)  

    We have fabricated a new lateral field emitter array, in-situ vacuum-sealed, which exhibits a low turn on voltage and a high transconductance value without any additional vacuum sealing process. The vacuum-sealed lateral FEA (VLFEA) is encapsulated during the fabrication process, so that field emission characteristics can be measured without any additional vacuum environments. Experimental current-voltage (I-V) characteristics show that the anode current is field emission current obeying the linearity of the Fowler-Nordheim (F-N) plot. The experimental turn-on voltage of about 9 V is in good agreement with the extracted one from the F-N plot. In order to verify the integrity of the vacuum sealed micro-cavity, we have measured the anode current of the VLFEA both in a high vacuum chamber and in an atmospheric environment and found that the structure is well sealed. The anode currents as a function of gate voltage of the Mo-sealed VLFEA are analyzed and transconductance is extracted. The experimental results show that the VLFEA has superior field emission characteristics, such as low turn-on voltage and high transconductance, and does not require any additional troublesome vacuum sealing View full abstract»

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  • Performance characteristics of an MSDC IOT amplifier

    Publication Year: 2001 , Page(s): 116 - 121
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (108 KB)  

    The design and performance of an inductive output tube (IOT) based amplifier incorporating multistage depressed collector (MSDC) technology is summarized in this paper. The amplifier performance goal was to provide an enhanced efficiency rf amplifier for the UHF digital television broadcast market. The operational frequency of the amplifier is 470 to 820 MHz. The design emphasizes simplicity to minimize upgrade requirements for existing digital television transmitter designs and insure a low cost IOT. The enhanced efficiency IOT is based on an existing standard collector IOT capable of providing peak envelope powers of 60 kW. The collector design incorporates three elements with one element serving as a depression stage. The collector design curtails the reflection of spent beam electrons back to the IOT interaction gap and minimizes the generation of secondary electrons at critical collector surface locations. Testing emphasized the 8-VSB modulation scheme adopted by the ATSC for digital television broadcasting. Performance results indicate that the IOT electrical efficiency increased from 34% to 51% with the addition of MSDC collector when the amplifier is operated at 15 kW average rf power using the 8-VSB modulation scheme View full abstract»

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  • Development of linear traveling wave tubes for telecommunications applications

    Publication Year: 2001 , Page(s): 74 - 81
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    Traveling wave tubes (TWTs) designed for telecommunications applications in multichannel power amplifiers (MCPAs) are required to have high linearity, low intermodulation distortion, high efficiency and high power outputs. The linearity of the TWT can be greatly improved by operation of the tube significantly backed off from saturation and by optimization of the design of the helix circuit. This results in two tone intermodulation products that are 25 to 40 dB below the carrier level, depending on the amount of back-off selected. However, operation backed off from saturation results in a greatly reduced efficiency of the TWT, which must be compensated for by optimal circuit and collector design. Several L-band and S-band Hughes TWTs have been developed for telecommunications applications and feature saturated power levels of up to 2 kW and average power of over 600 W with overall efficiencies of over 20% at 10 dB back-off and 40% at 6 dB back-off. These tubes provide high average power, high efficiency amplification with modest size and reduced cooling requirements compared to solid state amplifiers View full abstract»

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  • The Hobetron-a high power vacuum electronic switch

    Publication Year: 2001 , Page(s): 122 - 128
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    This paper describes a new high-power, hollow electron beam, current-regulating switch tube that we call the Hobetron. Experimental data on the Litton L-6026 Hobetron, an engineering prototype designed to stand off 125 kV dc and switch 200 amps, has demonstrated that Hobetron performance is in excellent agreement with computer predictions over the range of test. Further, the data confirmed that L-6026 switch power loss is less than 20% that of standard magnetron injection gun (MIG) switch tubes (for similar currents through each). Various potential Hobetron applications are presented throughout the paper. It is possible to include an additional electrode in the basic Hobetron configuration for even higher voltage standoff and switch current capability, and the paper presents an arrangement capable of standing off 500 kV dc and switching 500 amps. Simulations of a superpower “Hobetron-Plus” are presented, and the potential of this device as an efficient, 50 MW peak, relatively compact, VHF power amplifier for advanced heavy-particle (e.g., muon) colliders, is evaluated View full abstract»

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  • Computer simulation of intermodulation distortion in traveling wave tube amplifiers

    Publication Year: 2001 , Page(s): 178 - 180
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (56 KB)  

    The intermodulation performance of a helix TWT was computed using a large-signal disc model with two, three and eight correlated carriers and also using the program IMAL which models a generalized nonlinearity described by its single-carrier transfer characteristics. The results obtained by both methods showed good agreement. The intermodulation performance of a TWT for both correlated and uncorrelated carriers can therefore be predicted from its single-carrier transfer characteristics if they do not change significantly over the frequency range of interest View full abstract»

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  • Simulation of noise-power ratio with the large-signal code CHRISTINE

    Publication Year: 2001 , Page(s): 32 - 37
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (140 KB)  

    This paper describes simulations of the noise-power ratio (NPR) for a helix traveling wave tube (TWT) performed with the large-signal, one-dimensional (1-D), multifrequency code CHRISTINE. The results obtained with this code are in better agreement with measured values than are the more traditional values calculated by power series. We conclude that NPR simulations with large-signal codes have the potential to shorten the design phase of TWTs by eliminating the need for repeated build-test cycles to meet a required NPR View full abstract»

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  • Micromachining technology for lateral field emission devices

    Publication Year: 2001 , Page(s): 166 - 173
    Cited by:  Papers (16)  |  Patents (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    We demonstrate a range of novel applications of micromachining and microelectromechanical systems (MEMS) for achieving efficient and tunable field emission devices (FEDs). Arrays of lateral field emission tips are fabricated with submicron spacing utilizing deep reactive ion etch (DRIE). Current densities above 150 A/cm2 are achieved with over 150·106 tips/cm2. With sacrificial sidewall spacing, electrodes can be placed at arbitrarily close distances to reduce turn-on voltages. We further utilize MEMS actuators to laterally adjust electrode distances. To improve the integration capability of FEDs, we demonstrate batch bump-transfer of working lateral FEDs onto a quartz target substrate View full abstract»

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  • Transient ion disturbances in traveling wave tubes

    Publication Year: 2001 , Page(s): 82 - 87
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB)  

    It is well known that the presence of ions in the electron beam of a traveling wave tube (TWT) can lead to periodic variations in the output power, phase and the body (or helix) current. This has been referred to as ion noise or jitter. Recently, we have observed a different form of jitter, and while it is still observed as a small variation in the TWT output (typically <0.5 dB in power and 2° in phase), it is not periodic. We refer to this phenomenon as random jitter, since its random nature in time is a defining characteristic, Other characteristics include a relatively fast onset (~1 ms) and slow (~500 ms) recovery. It was found that random jitter was due to the spurious release of extremely small amounts of trapped gas inside the TWT. The source of the gas was identified and the problem was resolved. The observed level of fluctuations in power and phase had no effect on digital traffic and the small quantity of gas was found to have no measurable impact on cathode life View full abstract»

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  • Development of a low voltage power booster TWT for a Q-band MMPM

    Publication Year: 2001 , Page(s): 180 - 182
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (104 KB)  

    Compact millimeter wave amplifiers with output powers ranging from around 20 to 100 W are required for a number of important military and commercial applications. This paper describes the design of a miniature, low voltage, vacuum power booster TWT for a Q-band (40-45 GHz) millimeter wave power module (MMPM). At a design voltage of 7.7 kV and a maximum current of 120 mA, an output power goal of greater than 40 W of CW rf output power has been established for the Q-band TWT. Beam confinement is provided using an optimized samarium cobalt PPM stack. Circuit losses at millimeter wavelengths are minimized using a novel wire-wrapped, T-shaped BeO rod support structure. Output power is transmitted through a 0.051 cm, thick alumina ceramic output window. High overall device efficiency is achieved through the use of a 3 stage depressed collector. A recently completed engineering prototype produced 51 W of CW power at 41 GHz. Experimental overall device efficiency was 34.5%. These results will be described, as well as ongoing work to further improve overall device performance View full abstract»

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  • Effect of geometric azimuthal asymmetries of PPM stack on electron beam characteristics [TWTs]

    Publication Year: 2001 , Page(s): 38 - 44
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    A three-dimensional (3-D) beam optics model has been developed using the electromagnetic particle-in-cell (PIC) code MAFIA. The model includes an electron beam with initial transverse velocity distribution focused by a periodic permanent magnet (PPM) stack. All components of the model are simulated in three dimensions, allowing several azimuthally asymmetric traveling wave tube (TWT) characteristics to be investigated for the first time. These include C-magnets, shunts and magnet misalignment and their effects on electron beam behavior. The development of the model is presented and 3-D TWT electron beam characteristics are compared in the absence of and under the influence of the azimuthally asymmetric characteristics described View full abstract»

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  • Analytical electrostatic model of silicon conical field emitters. II. Extension to devices with focusing electrode

    Publication Year: 2001 , Page(s): 144 - 148
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (100 KB)  

    For pt. I see ibid., vol.48, no.1, p.134-43 (Jan. 2001). We extended the “bowling pin model” (BPM) presented in pt. I, to the case of double-gated conical field emitters. The model was used for trajectory calculations for both the single-gated and double-gated devices. Analysis also produced the governing relationship for the optimal operating voltages on the gate and focus electrodes of a double-gated emitter View full abstract»

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  • First pass TWT design success

    Publication Year: 2001 , Page(s): 176 - 178
    Cited by:  Papers (9)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (180 KB)  

    Making use of an ensemble of computer codes, Hughes Electron Dynamics (HED) has achieved first pass success in the design of slow wave circuits for several traveling wave tubes (TWTs) during the last year. By first pass design success we mean that when tested, the first device fabricated achieved the design goals for RF output power, basic efficiency, gain and phase shift. The design goals are derived from the predictions of a computer model, based on the exact dimensions of the TWT. The establishment of accurate computer models for the TWT slow wave circuit has enabled the optimization of a new design on the computer, eliminating the need for several experimental iterations in the development process. This accomplishment has enabled HED to significantly reduce the time required to develop new devices and demonstrate new design concepts View full abstract»

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  • Fast frequency-step-tunable high-power gyrotron with hybrid-magnet-system

    Publication Year: 2001 , Page(s): 101 - 107
    Cited by:  Papers (25)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (180 KB)  

    The TE22,6 1 MW gyrotron operated at Forschungszentrum Karlsruhe (FZK) at frequencies between 114 and 166 GHz has been investigated with respect to the fast-frequency tunability in the frequency range from 132 to 147 GHz. For that purpose, the gyrotron has been equipped with a special hybrid-magnet system consisting of superconducting (sc) magnets in the cryostat and additional normal conducting (nc) copper magnets with a fast time constant. Some special problems due to the magnetic coupling between the different magnets were investigated by calculation and experiment. Making use of these investigations some different current regulation systems for the nc magnets were implemented and tested experimentally. Finally a step-tuning operation between the modes from TE20,6 to TE24,6 in time steps of 1 s has been achieved View full abstract»

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  • Analytical electrostatic model of silicon conical field emitters. I

    Publication Year: 2001 , Page(s): 134 - 143
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    We present an analytical electrostatic model for a conical field emitter surrounded by a circular gate. The model is based on a radially symmetric orthonormal expansion of the potential throughout all space in the basis of Legendre functions of nonintegral degrees. The “bowling pin” model (BPM) makes it possible to calculate the total emission current and electron trajectories. The calculated values of the emitted current are in good agreement with the data. The value for the tip radius of curvature (ROC) obtained as the adjustable parameter in the model is in good agreement with that obtained from independent numerical modeling of the same devices View full abstract»

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  • Computer simulation of ion trapping and detrapping in a PPM focused traveling wave tube

    Publication Year: 2001 , Page(s): 56 - 61
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (204 KB)  

    This paper presents results from a time-dependent, electrostatic electron gun simulation code, simulating ion trapping and detrapping in a traveling wave tube (TWT) focused by periodic permanent magnets (PPM). The simulations described indicate that ion loss is primarily radial through the beam tunnel walls, rather than axial through the gun or collector. The electrostatic potential well formed by the electron beam is constantly being filled by ionization of a background neutral gas. This effect constitutes the primary ion loss mechanism. Filling of the potential well is made possible by loss of the low energy electrons produced by ionization (secondary electrons) through periodic nulls in the magnetic field View full abstract»

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  • COCA: a novel 3-D FE simulator for the design of TWT's multistage collectors

    Publication Year: 2001 , Page(s): 24 - 31
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    In this paper, the simulator COCA, a novel fully three-dimensional (3-D) finite-element (FE) tool for the design of multistage depressed TWTs collectors is illustrated. COCA has been developed at the University of Catania under an ESA/ESTEC project. The complete simulator consists of three main modules: a fully 3-D deterministic/neural FE mesh generator, an FE Vlasov solver coupled with an electron trajectory tracer taking into account also external magnetic fields, and a postprocessing module for result restitution, including secondary electron emission effects. All the functions are interactively managed and executed by means of an especially developed user-friendly graphical user interface which controls all the various aspects of a simulation session. The results of a simulation test performed on an asymmetric collector are also reported showing excellent agreement with available measured data. The COCA simulator provides the user with flexible and effective tools to design, test, optimize, and verify innovative asymmetrical geometries for TWT collectors View full abstract»

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  • Numerical solution of fields in lossy structures using MAGY

    Publication Year: 2001 , Page(s): 45 - 55
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    Lossy structures are used in vacuum electronic devices to control and suppress modes. Numerical simulation of the effect of these lossy structures is critical to the design and optimization of devices. The gyrotron simulation code MAGY makes use of the generalized telegraphist's equations in which the transverse structure of fields is represented as a sum of local modes of a metallic waveguide. If the wall is not a perfect conductor then sum over modes is not uniformly convergent. We have developed an algorithm to deal with this problem and allow for the simulation of structure with highly lossy walls. The theory and implementation of this algorithm are presented View full abstract»

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  • 60-GHz space TWT to address future market

    Publication Year: 2001 , Page(s): 68 - 71
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (108 KB)  

    The market situation of space traveling wave tubes (TWTs) over the last four years is reviewed. It is exemplified that space TWTs are not only the key components for the traditional frequency ranges in C- and Ku-band, but also for new satellite communication systems as digital audio broadcasting in the lower L- and S-band frequency range and the planned, new global multimedia systems. There, Thomson Tubes Electroniques GmbH (TTEG) has developed the new family of Ka band TWTs, which provide the large bandwidth and power requirements for high data rate transmission. TTEG is also developing 60-GHz TWTs as RF intersatellite-links for global satellite systems. The promising results of the 560 g lightweight, 25 W, broadband helix TWT are mainly reported and the requirements compared with those for a parallel 60 W 60-GHz interdigital line TWT development View full abstract»

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  • Silicide application on gated single-crystal, polycrystalline and amorphous silicon FEAs. I. Mo silicide

    Publication Year: 2001 , Page(s): 149 - 154
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (156 KB)  

    In order to improve both the level and the stability of electron field emission, the tip surface of silicon field emitters have been coated with a molybdenum layer of thickness 25 nm through the gate opening and annealed rapidly at 1000°C in inert gas ambient. The gate voltages of single-crystal silicon (c-Si), polycrystalline silicon (poly-Si) and amorphous silicon (a-Si) field emitter arrays (FEAs) required to obtain anode current of 10 nA per tip are 90 V, 69 V, and 84 V, respectively. In the case of the silicide emitters based on c-Si, poly-Si and a-Si, these gate voltages are 76 V, 63 V, and 69 V, respectively. Compared with c-Si, poly Si and a-Si field emitters, the application of Mo silicide on the same silicon field emitters exhibited 9.6 times, 2.1 times, and 4.2 times higher maximum emission current, and 6.1 times, 3.7 times, and 3.1 times lower current fluctuation, respectively. Moreover, the emission currents of the silicide FEAs depending on vacuum level are almost same in the range of 10-9~10-6 torr. This result shows that silicide is robust in terms of anode current degradation due to the absorption of air molecules View full abstract»

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  • Design of a Ka-band gyro-TWT for radar applications

    Publication Year: 2001 , Page(s): 108 - 115
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    The design of a Ka-band gyrotron traveling wave tube (TWT) amplifier capable of operating over a wide range of peak powers and bandwidths is presented. The amplifier operates in the TE11 mode at the fundamental cyclotron harmonic. Instantaneous bandwidths in the range of 2.5 to 3.9 GHz (at 1 dB below saturation) with corresponding peak powers between 92.2 and 57.9 kW can be achieved by simply adjusting the mod-anode voltage of the electron gun. The corresponding gains range from 57.1 to 36.0 dB. The design performance is obtained with a high quality, 6 A, 70 kV electron beam generated with a double-anode magnetron injection gun. This wide range performance capability in the design is achieved via the use of the distributed loss approach in the interacting circuit, which also guarantees zero-drive stability. A diffractive loading scheme is employed in the lossy section of the circuit to ensure high average power operation of the amplifier View full abstract»

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  • A three-dimensional multifrequency large signal model for helix traveling wave tubes

    Publication Year: 2001 , Page(s): 3 - 11
    Cited by:  Papers (50)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    A three-dimensional (3D) multifrequency large signal model of the beam wave interaction in a helix TWT is described. The beam is divided into a set of discrete rays, or “beamlets”, instead of the disks or rings used in one-dimensional (1-D) or two-dimensional (2-D) models. The RF fields supported by the helix are represented by a tape helix model that uses a modal expansion including the full (Bessel function) radial dependence of the fields; both forward and backward synchronous space harmonics are included in the model. RF space charge fields are obtained from solutions of the Helmholtz equations for the RF electric and RF magnetic fields, using the beam current and charge densities as sources. The dc space charge electric field is similarly obtained from a solution of Poisson's equation. This model has been implemented in a code called CHRISTINE 3D, a generalization of the one dimensional CHRISTINE code. The full three dimensional treatment permits the accurate computation of large signal gain and efficiency, taking into account the self-consistent variation of beam radius along the interaction space. The code also computes helix interception current and transverse beam distributions at the entrance to the collector-important design data that are unavailable from a 1D model. Results from the CHRISTINE 3D code are shown to compare very favorably with measurements of output power, efficiency, and interception current vs. drive power. Its predictions for spent beam distributions also compare very well with measurements. Run times for the code are problem dependent, but for a single case of interest are typically 1 to 5 min on a 450 MHz PC, orders of magnitude shorter than that required for a comparable 3D particle-in-cell simulation View full abstract»

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  • Tape helix perturbation including 3-D dielectrics for TWTs

    Publication Year: 2001 , Page(s): 12 - 23
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (284 KB)  

    A perturbation technique described in a previous paper has been applied to the tape helix model of a traveling wave tube (TWT). The perturbation technique employs two solutions; the unperturbed solution is that for a helix in a conducting sleeve, suspended in vacuum, and the perturbed solution is with the above configuration, but with the introduction of dielectric support rods. Usually the perturbed solution is not known and is approximated by the homogeneous dielectric solution. Then in three-dimensional (3-D) fashion, the perturbation technique weights the dielectric with an energy-like term that is only evaluated within the discrete dielectric. Therefore, the model accounts for the distribution of dielectric material. Extending the perturbation to the tape helix, the current density is accurately portrayed in space. In all cases, the perturbed tape helix solution has a lower least square error in normalized phase velocity than the unperturbed tape helix solution. It had a lower error than the perturbed sheath helix solution of the previous paper, which in turn had a lower least square error than the Naval Research Laboratory's (NRL's) Small Signal Gain (SSG) Program. An initial discussion of the tape helix is presented and the calculated dispersion relation given. This solution incorporates a conducting backwall or shield with a homogeneous dielectric between it and the helix, using n=-6 to n=+6 space harmonics. Then the perturbation theory is applied, first for uniform support rods, and then to include notched rods. The resultant simulations produce phase velocity and coupling impedance data. Deviation from theory to experiment is reported by comparing the square root of the average sum of the squares difference, divided by an average phase velocity, between calculated phase velocities and a second order least squares fit of the measured data. Experimental data on the dispersion properties of four helices came from Northrop. The average error in phase velocity for four cases was 0.95%. For uniform rods the perturbation theory lowers the phase velocity, but doesn't significantly alter the dispersion. However, for notched rods, the perturbation theory raises the phase velocity and flattens the dispersion, in agreement with experiment. Computations can be performed in 1/2 min for a ten-frequency-step problem on a Pentium II processor View full abstract»

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  • Advances in space TWT efficiencies

    Publication Year: 2001 , Page(s): 174 - 176
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (56 KB)  

    Overall dc-to-rf conversion efficiency continues to be the single most significant figure of merit for commercial space traveling wave tube amplifiers (TWTAs). Improvements in TWTA efficiency immediately translate into potential revenue increases for satellite operators, since additional transponders can be carried on board the spacecraft for the same prime power and waste heat handling capacity. The revenue implications of increased efficiency have spurred TWT manufacturers to continue wringing out every possible increase in efficiency. By optimizing both rf circuit and collector designs, overall efficiencies >70% have now become routine. This paper will discuss the results of several experiments to improve TWT efficiency demonstrating how these impressive efficiencies may be achieved View full abstract»

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  • Mode selection in high power microwave sources

    Publication Year: 2001 , Page(s): 129 - 133
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB)  

    In designing a microwave generator or an amplifier of enhanced power, we always risk encountering self-excitation of unwanted oscillations. To suppress parasitic oscillation modes, we may implement a selective rf absorber, organize a selective feedback, taper the rf structure profile to admit only the main operation mode into the wave-electron synchronism band, etc. At a proper switching-on scenario, the main operation mode of the device can suppress its rivals at the nonlinear interaction stage. This brief review is aimed to systematize numerous methods efficiently used to keep the coherence in high power vacuum devices based on the stimulated radiation by electron beams View full abstract»

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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