Download or read book Study of RF Modulated Crossed Field Amplifiers written by Kenneth W. Dudley and published by . This book was released on 1970 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study of rf modulated crossed field amplifiers (CFA), is being pursued in two areas: the ability of the CFA to be pulse modulated using rf drive power only (rf keying), and the instantaneous bandwidth capability of backward-wave devices. For the rf keying experiments, a special L-band forward-wave test vehicle was designed and built with a multi-section (5) cathode, each section insulated from the others. This design permits application of various bias voltages to different cathode sections to determine the optimum configuration for rf keying conditions. The design also permits measurement of the distribution of the current around the cathode as well as the power dissipated in different sections of the cathode and anode. Details of the tube construction are given in the report. Test results are also described for tests performed with a forward-wave tube having a single cutoff electrode which was biased at various voltage levels to achieve rf keying. Two S-band backward-wave CFA's were constructed for studies of instantaneous bandwidth capability, and a modulator was assembled for test equipment. Tube design characteristics and test data are presented, as is an analysis of the CFA-modulator interface that was examined to determine the characteristics that are influenced by very rapid frequency or rf phase changes. (Author).

Download or read book Simulation of a Crossed field Amplifier Using a Modulated Distributed Cathode written by Marcus Pearlman and published by . This book was released on 2017 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Current crossed-field amplifiers (CFAs) use a uniformly distributed electron beam, and in this work, the effects of using a spatially and temporally controlled electron source are simulated and studied. Spatial and temporal modulation of the electron source in other microwave vacuum electron devices have shown an increase in gain and efficiency over a continuous current source, and it is expected that similar progress will be made with CFAs. Experimentally, for accurate control over the electron emission profile, integration of gated field emitter arrays (GFEAs) as the distributed electron source in a crossed-field amplifier (CFA) is proposed. Two linear format, 600 and 900 MHz CFAs, which use GFEAs in conjunction with hop funnels as an electron source, were designed, modeled in VSim, and built at BSU. The hop funnels provide a way to control the energy of the electron beam separately from the sole potential and to protect the GFEA cathode. The dispersion of the meandering microstrip line slow wave circuit used in the device and the electron beam characteristics were measured and validated the simulation model, but experiments failed to show electron beam interaction with the electromagnetic wave due to insufficient current from the available cathode. To complete the research, a working CFA built at Northeastern University (NU) was modeled. The NU CFA was a linear format, device operating at 150 MHz, with 10 W of RF input power, and typically 150 mA of injected beam current. The electrically short device (6 slow wave wavelengths long) achieved 7 dB of gain. After validating the Vsim model against the experimental results, an electrically longer version (9 wavelengths) was simulated with both an injected beam and distributed cathode. To model the distributed cathode computationally efficiently, where the emitted electron energy can be controlled separately from the sole potential, a new electron injection method was developed, using a divergence-free region. Static electron emission profiles showed no improvement over the injected beam model but the temporally modulated cathode was found to significantly improve the performance. It was found that the temporal modulation could improve the small-signal-gain from 13 dB for an unmodulated source to 25 dB with an injected current of 150 mA and 0.1 W of RF drive power. This improvement is only likely to be observed for higher power devices (>10 kW) because of the additional RF drive power required by the GFEA, however. For larger RF drive powers, the improvements to gain become much smaller. With an RF drive power of 10 W, the modulated cathode showed 9 dB of gain, and the injected beam variant showed 8 dB. The signal-to-noise ratio (SNR) using the modulated cathode was consistently at least 15 dB higher than the SNR of the unmodulated cathode. This reduces the likelihood of excitation of unwanted modes. Even though this device showed small improvements to gain at large RF drive powers, it is proposed here that improvements to maximum power in higher power devices are likely, due to the inherent mode-locking mechanism of the modulated cathode, but this still needs to be confirmed. Previous research studying the effects of a modulated cathode in a magnetron and the improvements to the SNR shown here, show promise in this regard."--Boise State University ScholarWorks.

Download or read book RF Modulated S Band Crossed Field Amplifier written by L. Lemanski and published by . This book was released on 1970 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: The program has the objective to design, develop, construct, and evaluate a high power S-band reentrant stream, crossed-field amplifier utilizing automatic self-modulation by RF drive power. The report covers the design considerations and cold test evaluation of the slow wave anode circuit, anode and cathode cooling techniques, and general construction of the proposed amplifier. Background information is given presenting the principles of operation of a reentrant stream crossed-field amplifier using a dc voltage between the cathode and the anode and a dc biased turn-off electrode to achieve automatic self-modulation by RF drive power. The results of one experiment intended to complete a series of experimental investigations of bias electrode geometries performed on another program are given. No significant additional improvement was obtained, but the experiment did confirm the present understanding of bias electrode operation. (Author).

Download or read book Study of Crossed Field Amplifiers written by Whinnery John. R. and published by . This book was released on 1959 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book STUDY OF CROSSED FIELD AMPLIFIERS written by R. A. Rao and published by . This book was released on 1965 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contents: Shielded-gun crossed-field amplifier; Backward-wave noise-figure studies; Noise-figure studies on forwardwave crossed-field amplifier; Cathode-region studies on crossed-field tubes; Characteristics of the smooth-bore magnetron.

Download or read book Printed Circuit RF Keyed Crossed Field Amplifier written by W. E. Courtney and published by . This book was released on 1975 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report describes an experimental and theoretical study of an RF-keyed linear format Crossed-Field Amplifier, (CFA), using a printed-circuit slow-wave structure. The theoretical results indicate that higher interaction impedances than have presently been obtained with printed-circuit slow-wave structures will be required to achieve the goal of low RF-keying levels. Experimental results indicate good agreement between theory and experiment for the phase velocity of the slow-wave structure and reasonable agreement between theory and experiment for the CFA.

Download or read book Printed circuit RF keyed Crossed field Amplifiers written by William E. Courtney and published by . This book was released on 1975 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Crossed Field Amplifier CFA Characterization and Theory written by Michael L. Cooke and published by . This book was released on 1973 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this program was the establishment of a computer program for optimizing the design of high power crossed-field amplifiers (C.F.A.'s). The basic tasks of this study were to: (1) Critically evaluate the predictive value of existing large signal Crossed-Field Amplifiers theories or computer codes, and improve their quantitative performance by revision of assumptions and physical concepts as emerging from the comparison between experimental and theoretical results. (2) Investigate the electron flow in the crossed-field gridded gun and resultant non-homogeneities. (3) Examine the electron flow (for the cold electron case) in the crossed-field gun, analytically and/or by numerical computations to achieve self consistency for the solutions of the dynamic and the field equations. (4) Compare theoretical results with actual data as obtained from experiments with gridded crossed-field guns and so assess the value of theoretical achievements. Incorporate for this purpose the functional dependence of the gun performance on various parameters which may be subject to variations in actual tube production and/or operation.

Download or read book Modeling and Design Techniques for RF Power Amplifiers written by Arvind Raghavan and published by John Wiley & Sons. This book was released on 2008-02-04 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Achieve higher levels of performance, integration, compactness, and cost-effectiveness in the design and modeling of radio-frequency (RF) power amplifiers RF power amplifiers are important components of any wireless transmitter, but are often the limiting factors in achieving better performance and lower cost in a wireless communication system—presenting the RF IC design community with many challenges. The next-generation technological advances presented in this book are the result of cutting-edge research in the area of large-signal device modeling and RF power amplifier design at the Georgia Institute of Technology, and have the potential to significantly address issues of performance and cost-effectiveness in this area. Richly complemented with hundreds of figures and equations, Modeling and Design Techniques for RF Power Amplifiers introduces and explores the most important topics related to RF power amplifier design under one concise cover. With a focus on efficiency enhancement techniques and the latest advances in the field, coverage includes: Device modeling for CAD Empirical modeling of bipolar devices Scalable modeling of RF MOSFETs Power amplifier IC design Power amplifier design in silicon Efficiency enhancement of RF power amplifiers The description of state-of-the-art techniques makes this book a valuable and handy reference for practicing engineers and researchers, while the breadth of coverage makes it an ideal text for graduate- and advanced undergraduate-level courses in the area of RF power amplifier design and modeling.

Download or read book Klystrons Traveling Wave Tubes Magnetrons Crossed field Amplifiers and Gyrotrons written by A.S. Gilmour Jr. and published by Artech House. This book was released on 2011 with total page 883 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microwave tubes are vacuum electron devices used for the generation and amplification of radio frequencies in the microwave range. An established technology area, the use of tubes remains essential in the field today for high-power applications. The culmination of the authorOCOs 50 years of industry experience, this authoritative resource offers you a thorough understanding of the operations and major classes of microwave tubes.Minimizing the use of advanced mathematics, the book places emphasis on clear qualitative explanations of phenomena. This practical reference serves as an excellent introduction for newcomers to the field and offers established tube engineers a comprehensive refresher. Professionals find coverage of all major tube classifications, including klystrons, traveling wave tubes (TWTs), magnetrons, cross field amplifiers, and gyrotrons."

Download or read book Research and Development on L band Crossed field Amplifier Chain written by A. Wilczek and published by . This book was released on 1965 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: A crossed-field amplifier for use in an L-band phased array radar has been developed. The SFD-209 is designed to be stacked on half-wavelength centers in a permanent magnet array. The tube will generate peak power up to 150 kw with 16 db gain at an efficiency of 50% over a 100 Mc band centered on 1200 Mc, with exceptional phase characteristics. Average power of 1.5 kilowatts and operating life in excess of 5000 hours have been demonstrated. The SFD-209 operates from a dc power supply with very low modulator power. Cold cathode operation with RF turn on and control electrode turn off is used. The duty cycle may be changed instantaneously by changing repetition rate and/or pulse width with no change in modulator power on a per pulse basis. Pulse widths from 0.1 microsec to 600 microsec and repetition rates as low as 1 pulse per minute have been demonstrated. The ability to pulse code a CW input signal and the ability to amplify a complex signal have been demonstrated. (Author).

Download or read book Design of a High Power Cross Field Amplifier at X Band with an Internally Coupled Waveguide written by and published by . This book was released on 1991 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cross field amplifiers (CFA) have been used in many applications where high power, high frequency microwaves are needed. Although these tubes have been manufactured for decades, theoretical analysis of their properties is not as highly developed as for other microwave devices such as klystrons. We have developed a simulation model for CFAs using the PIC code CONDOR. Our simulations indicate that there are limits to the maximum RF field strength that a CEA can sustain. When the fields become too high, efficiency becomes very poor, and the currents drawn may become so large that secondary emission cannot be maintained. It is therefore desirable to reduce the circuit impedance of a very high power tube. One method for doing this, proposed by Feinstein, involves periodically coupling a standard CFA circuit to an internal waveguide. Most of the power flows in the waveguide, so the overall impedance is much reduced. By adjusting the guide dimensions one can vary the impedance. Thus one can retain high impedance at the low power end but low impedance at the high power end. In principle one can maintain constant RF voltage throughout the tube. CONDOR simulations have identified a good operating point at X band, with power generation of over 5 MW per cm and total efficiency of over 60 percent. ARGUS simulations have modelled the cold test properties of the coupled structure. The nominal design specifications are 300 MW output, 17 db gain, frequency 11.4 GHz, dc voltage 142 kV, magnetic field 5 kG, anode cathode gap 3.6 mm, total interaction length about 60 cm. We will discuss the results of code simulations and report on the status of the experimental effort.

Download or read book Crossed field Microwave Devices V3 written by G Mourier and published by Elsevier. This book was released on 2012-12-02 with total page 671 pages. Available in PDF, EPUB and Kindle. Book excerpt: Crossed-field Microwave Devices, Volume I: Principal Elements of Crossed-Field Devices focuses on the developments, trends, and approaches in the study of crossed-field microwave devices. The selection first offers information on periodic structures and cathode gun and its static characteristics. Discussions focus on circuits for traveling wave crossed-field tubes; effect of tolerance on interdigital lines; mode spectrum of strapped type magnetron; and electron gun optics and associated static characteristics of injection systems. The text then takes a look at noise and space-charge modes, including preoscillation phenomena in space-charge clouds below the main oscillation threshold; cutoff characteristics of the static magnetron diode; magnetron diode oscillations; and noise in crossed-field electron beams. The manuscript then examines the interaction of beams and circuits, as well as small and large signal theory and experiment. The selection is a valuable reference for readers interested in the elements of crossed-field microwave devices.

Download or read book Analysis of Distributed Emission Crossed Field Amplifiers written by and published by . This book was released on 1977 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computer simulation has been used to aid in the development of the Raytheon QKS 1705 and QKS 1842 backward-wave distributed-emission crossed-field amplifiers. At present, Shared Applications, Inc. models a reentrant tube with a planar electrode configuration. The results give insight into the electron dynamics and show good qualitative agreement with measurements. Apparently no steady RF state exists; instead the output power and anode current fluctuate by several percent over the transit time around the tube (fifteen RF periods). To simulate a backward-wave amplifier with the planar model, it is necessary to supply an estimate of RF output power and derive the RF drive power. An alternative cylindrical model has demonstrated the ballistic starting mechanisms in the CFA. This model is capable of including the space-charge forces and the complete RF interaction in both forward- and backward-wave tubes and is recommended for further development.

Download or read book STUDY OF CROSSED FILED AMPLIFIERS written by J. Christensen and published by . This book was released on 1967 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of the work was to study the interaction of electromagnetic waves and electrons in vacuum and solids. Both theoretical and experimental studies of noise phenomena in crossed-field vacuum devices were conducted. The experimental work was a detailed investigation of the dependence of the noise figure of a crossed-field amplifier on various parameters when operated both in the forward-wave and backward-wave modes. The design of another amplifier utilizing the knowledge derived from experiments on the first one and on theoretical conclusions has been developed with the aim to attaining an evaluation of the minimum noise figures for comparison with the O-type amplifiers. One part of the theoretical work was aimed at modifying an existing theory of crossed-field noise figures to include additional effects in an effort to reach better agreement with the (lower) experimental values. Another phase of the theoretical work was directed toward developing a coupled-mode description of the crossed-field amplifier and generalized noise-figure expressions. A study of the crossed-field potential minimum using a feedback model to represent the two-dimensional processes involved in the space-charge effects on the emission perturbations has been made.

Download or read book Study of Crossed field Amplifiers written by University of California, Berkeley. Electronics Research Laboratory and published by . This book was released on 1959 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 1460 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.