摘要:

There is a need for high power RF sources for the next generation of accelerators and colliders. Sources that operate at reduced beam voltage allow solid state power supplies with significant cost reduction over conventional pulse modulators. Multiple beam RF sources provide reduced beam voltage by using a multiplicity of beamlets that traverse the RF circuit through individual beam tunnels, reducing the space charge forces that drive the voltage requirement. The current generation of multiple beam devices typically use Brillouin focusing, which limits high power operation. The devices reported here utilize confined flow focusing which allows much tighter control of the electron beamlets and consequently, higher power operation. Progress in the development of a 100 MW multiple beam electron gun with confined flow focusing is reported. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635106

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Calabazas Creek Research, Inc. is developing an X‐band 50 MW multiple beam klystron (MBK) on a DOE SBIR Phase II grant. The electrical design and preliminary mechanical design were completed on the Phase I. This MBK consists of eight discrete klystron circuits driven by eight electron beams located symmetrically on a circle with a radius of 6.3 cm. Each beam operates at 190 kV and 66 A. The eight beam electron gun is in development on a DOE SBIR Phase II grant. Each circuit consists of an input cavity, two gain cavities, three penultimate cavities, and a three cavity output circuit operating in the PI/2 mode. Ring resonators were initially proposed for the complete circuit; however, low beam — wave interaction resulted in the necessity to use discrete cavities for all eight circuits. The input cavities are coupled via hybrid waveguides to ensure constant drive power amplitude and phase. The output circuits can either be combined using compact waveguide twists driving a TE01high power window or combined into a TM04mode converter driving the same TE01window. The gain and efficiency for a single circuit has been optimized using KLSC, a 2 1/2D large signal klystron code. Simulations for a single circuit predict an efficiency of 53&percent; for a single output cavity and 55&percent; for the three cavity output resonator. The total RF output power for this MBK is 55 MW. During the Phase II emphasis will be given to cost reduction techniques resulting in a robust — high efficient — long life high power amplifier. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635107

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Calabazas Creek Research, Inc.(CCR) is developing rectangular, gridded, thermionic, dispenser‐cathode guns for sheet beam devices. The first application is expected to be klystrons for advanced particle accelerators and colliders. The current generation of accelerators typically use klystrons with a cylindrical beam generated by a Pierce‐type electron gun. As RF power is pushed to higher levels, space charge forces in the electron beam limit the amount of current that can be transmitted at a given voltage. The options are to increase the beam voltage, leading to problems with X‐Ray shielding and modulator and power supply design, or to develop new techniques for lowering the space charge forces in the electron beam. In this device, the beam has a rectangular cross section. The thickness is constrained as it would in a normal, cylindrically symmetric klystron with a Pierce gun. However, the width of the beam is many times the thickness, and the resulting cross sectional area is much larger than in the conventional device. This allows much higher current and/or a lower voltage before space charge forces become too high. The current program addresses issues related to beam formation at the emitter surface, design and implementation of shadow and control grids in a rectangular geometry. It is directed toward a robust, cost‐effective, and reliable mechanical design. A prototype device will be developed that will operate at 415 kV, 250 A for an 80 MW, X‐Band, sheet‐beam klystron. The cathode will have 100 cm2of cathode area with an average cathode current loading of 2.5 A/cm2. For short pulse formation, the use of a grid was chosen. The gun has been designed with a combination of 2‐D and 3‐D codes. 2‐D codes were used to determine the starting point for the electrodes to produce the compression (which is in only 1 direction.) These results showed that a very high quality beam could be achieved even in the presence of the shadow grid. 3‐D results have shown that the quality can be maintained for the actual geometry. Final designs of the gun are being completed, and fabrication is expected to begin in the spring of 2003. Details of the design will be reported. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635108

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The period 1946–1961 was a special era for microwave tubes, just after WWII, up until invention of the laser. Low noise, broadband, high power, high efficiency, from 60 MHz to 300 GHz, all done without modern computers (IC’s invented in 1959). The major universities and industrial research labs all had active microwave tube research, which was well supported. Beam type tubes of all kinds were invented and experimented with. The Pierce analytic approach became the norm for linear analysis. Time from conception to experiment was short from new guns to new circuits. This paper is one person’s experience at three universities and two industrial firms. Challenging, productive and rewarding. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635109

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

In the USSR, the first traveling wave tube (TWT) was developed in 1946. This was followed by the invention of the first backward‐wave oscillator (BWO) and other important achievements, which could characterize a strong competition existed between American and Soviet scientists and engineers. In the present paper, some of the achievements of the first soviet TWT team, headed by L. N. Loshakov, are discussed. Among those achievements are invention of the two‐anode gun for a low‐noise TWT, development of the first three‐octave TWT, and development of the helix TWT linear theory. In this paper, also such issues as formation of the rotating electron beams, suppression of reflected waves, multi‐stage TWTs, amplification without synchronizing electron and wave velocities, utilization of beryllium oxide and quartz rods in one RF set, dispersion control by application of metal support rods, and many other engineering solutions are presented. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635110

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

A reduction of development costs will have a significant impact on the total cost of the vacuum electron devices. Experimental testing cycles can be reduced or eliminated through the use of simulation‐based design methodology, thereby reducing the time and cost of development. Moreover, by use of modern optimization tools for automating the process of seeking specific solution parameters and for studying dependencies of performance on parameters, new performance capabilities can be achieved, without resorting to expensive cycles of hardware fabrication and testing. Simulation‐based‐design will also provide the basis for sensitivity studies for determining the manufacturing tolerances associated with a particular design. Since material properties can have a critical effect on the performance of the vacuum electron devices, the design tools require precise knowledge of material characteristics, such as dielectric properties of the support rods, loss profile etc. Sensitivity studies must therefore include the effects of materials properties variation on device performance. This will provide insight for choosing the proper technological processes in order to achieve these tolerances, which is of great importance for achieving cost reduction. A successful design methodology depends on the development of accurate and efficient design tools with predictive capabilities. These design tools must be based on realistic models capable of high fidelity representation of geometry and materials, they must have optimization capabilities, and they must be easy to use. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635111

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

TESLA (Telegraphist’s Equations Solution for Linear Beam Amplifiers) is a new code designed to simulate linear beam vacuum electronic devices with cavities, such as klystrons, extended interaction klystrons, twistrons, and coupled cavity amplifiers. The model includes a self‐consistent, nonlinear solution of the three‐dimensional electron equations of motion and the solution of time‐dependent field equations. The model differs from the conventional Particle in Cell approach in that the field spectrum is assumed to consist of a carrier frequency and its harmonics with slowly varying envelopes. Also, fields in the external cavities are modeled with circuit like equations and couple to fields in the beam region through boundary conditions on the beam tunnel wall. The model in TESLA is an extension of the model used in gyrotron code MAGY. The TESLA formulation has been extended to be capable to treat the multiple beam case, in which each beam is transported inside its own tunnel. The beams interact with each other as they pass through the gaps in their common cavities. The interaction is treated by modification of the boundary conditions on the wall of each tunnel to include the effect of adjacent beams as well as the fields excited in each cavity. The extended version of TESLA for the multiple beam case, TESLA‐MB, has been developed for single processor machines, and can run on UNIX machines and on PC computers with a large memory (above 2GB). The TESLA‐MB algorithm is currently being modified to simulate multiple beam klystrons on multiprocessor machines using the MPI (Message Passing Interface) environment. The code TESLA has been verified by comparison with MAGIC for single and multiple beam cases. The TESLA code and the MAGIC code predict the same power within 1&percent; for a simple two cavity klystron design while the computational time for TESLA is orders of magnitude less than for MAGIC 2D. In addition, recently TESLA was used to model the L‐6048 klystron, code predictions agree with measured data in saturated output power very well, while there is difference in gain, the predicted gain is slightly higher than measured. These discrepancies will be explored in future simulations on better‐diagnosed devices. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635112

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We present an overview of techniques and computer codes developed by us for systematic design of depressed collectors with special reference to devices that use gyrating electron beams. These techniques facilitate achievement of high power levels in electron tubes. ProfilEM is an aid to controlling the trajectories of primary electrons. BSCAT provides for tracing the trajectories of backscattered electrons. Multiple generations of backscatter can be obtained, while keeping the number of rays to be tracked within manageable limits. We describe examples of applying these codes to the case of two‐stage depressed collectors for a 1.5 MW 110 GHz gyrotron. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635113

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

A magnetron injection gun (MIG) with an inverted geometry is described. Use of an inverted geometry with the inner electrode at ground potential provides support for the inner coax portion of the cavities of a high power gyroklystron, and results in improved optics. The geometry of the gun is described and results of trajectory simulations are presented. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635114

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

A prototype, low‐repetition‐rate triaxial klystron amplifier (TKA) has been fabricated and tested. This device is powered by an annular electron beam (∼400 kV, 3.5 kA). The TKA operates at 9.3 GHz at power levels >100 MW and with a pulse duration of 750 nsec. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635115

出版商:AIP    

年代:1903

数据来源: AIP