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 TE/sub 11/ 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.

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

Extending the bandwidth and average power capability of vacuum electron devices for the next generation of millimeter wave radars is a major research goal at the Naval Research Laboratory. Gyro-amplifiers such as the gyroklystron and gyro traveling wave-tube (gyro-TWT) appear to be ideal candidates for this purpose due to their high power handling capability relative to their conventional counterparts, i.e., klystrons and coupled-cavity TWTs. This paper presents the design of a high-average power compatible, Ka-band gyro traveling-wave-tube (gyro-TWT). This amplifier design employs the circular TE/sub 11/ mode and operates at the fundamental cyclotron harmonic. In addition, this design makes use of the distributed loss approach, which has recently been demonstrated to be effective in the suppression of spurious oscillations in gyro-TWTs. The design has been performed using the self-consistent, time-dependent, quasi three-dimensional code MAGY. The code has been successfully used to model gyroklystrons and benchmarked against gyro-TWT linear theory. The code is capable of addressing issues such as absolute instabilities and the effect of reflections, which have also been investigated for this design.

/pdf/design-of-a-ka-band-gyro-twt-for-radar-applications-57h8wbz44n.pdf

Communications and Power Industries, Inc., has designed and manufactured two versions of a 10-MW-peak high-efficiency multiple-beam klystron (MBK) operating at 1300 MHz. This type of klystron is favored for large particle accelerator projects such as the European X-ray Free-Electron Laser at the Deutsches Elektronen Synchrotron (DESY). Two klystrons have been made for DESY. The first-generation MBK was a vertically oriented prototype using a six-cavity design with higher order mode input and output cavities and conventional intermediate cavities. For cost and performance reasons, the second-generation MBK, designated VKL-8301B, utilized seven coaxial fundamental-mode cavities and is an “industrialized” horizontally oriented klystron. The klystron was designed and optimized using state-of-the-art multidimensional design codes to ensure that all performance requirements are exceeded. Agreement between the simulated and measured performances is good. The VKL-8301B prototype achieved a peak saturated RF output power of 10.4 MW and 67.8% efficiency. The data were measured at the full 1.5% duty and with 1.5-ms pulse width. The klystron satisfied all required operating conditions, including stable operation into an output mismatch of 1.2:1 voltage standing wave ratio at various phases. The prototype has been shipped to DESY and has been successfully tested by a customer.

High-Power High-Efficiency L-band Multiple-Beam Klystron Development at CPI

The design and experimental study of a Ka-band gyrotron-travelling-wave tube (gyro-TWT) amplifier operating in the circular TE01 mode at fundamental cyclotron harmonic are presented. A mode-selective technique was adopted in the interaction circuit of the gyro-TWT to suppress spurious modes TE11 and TE21. A saturated peak power of 86 kW was obtained with saturated gain of 33 dB , an efficiency of 21.3%, in operating voltage 62 kV, electron current 6.5 A and -3 dB bandwidth of 2 GHz (~6%) .

Experimental Study of a Ka Band Gyro-TWT with the Mode-Selective Circuits

A metamaterial (MTM)-inspired interaction structure for MW-level klystron at 714 MHz is proposed. The electromagnetic characteristics of MTM-inspired resonant cavities with single-bridge complementary electric split ring resonators (CeSRRs) are studied, and the cold-tested results confirm the feasibility of miniaturizing the resonant cavity. Furthermore, the beam–wave interaction simulation for the interaction structure constructed by MTM-inspired resonant cavities with single-bridge CeSRRs is carried out, demonstrating 2.28 MW of output power at 714 MHz for a 100 kV, 40 A electron beam. The radius and length of the MTM-inspired interaction structure are 1/2 and 2/3 of the conventional counterparts, respectively. The promising performance makes it attractive for future applications such as linacs. 

Metamaterial-Inspired Interaction Structure for MW-Level Klystron at 714 MHz

A new line of high-efficiency multi-stage depressed collector (MSDC) klystron amplifiers has been developed by Communications and Power Industries Microwave Power Products (CPI/MPP) for use in satellite communications and scientific applications market. These klystrons are air-cooled with permanent magnet focusing. The first products are designed to service the satellite uplink and terrestrial repeater markets. MSDC technology for these applications can reduce power consumption by as much as 60%. A general discussion about the benefits of MSDC technology for these applications, as well as two examples of their use, are presented. CPI/MPP has developed the VKU-8891M series klystrons which provide 2.4 kW CW tunable in the frequency range from 17.3 to 18.4 GHz with instantaneous bandwidths up to 85 MHz. The klystron is designed with a 4-stage MSDC which has increased the saturated efficiency of the device from 24% to 40% A detailed discussion of the design, as well as a comparison between simulation and experiment, is presented. CPI/MPP is also developing the VKS-7964M klystron in the frequency range from 2.1 to 2.4 GHz, with instantaneous bandwidths up to 8 MHz. This klystron has a 4-stage MSDC. The simulated efficiency of this klystron approaches 60%. We predict the measured efficiency. A detailed discussion of the design, as well as a comparison between simulation and experiment, is presented.

Permanent magnet focused, multi-stage depressed collector klystron amplifiers for satellite communications

Communications and Power Industries has designed and manufactured the VKL-7967A, a high-efficiency, high CW power L-band klystron. The klystron operates at 1.3 GHz and is designed to saturate above 300 kW CW RF output with ≥65% efficiency. The users intend to operate in the linear range of the transfer curve and therefore required 270 kW CW RF output with ≥0.5dB/dB incremental gain and ≥52% minimum efficiency. Two klystrons have been manufactured and successfully tested. Their performance data are compared with the simulations performed during the design.

Development and production of a 1.3 GHz, 300 kW CW klystron

CPI has designed and is currently in the process of building a prototype of a horizontally oriented, ≥10 MW, ≥65% efficiency multiple beam klystron (MBK) operating at 1300 MHz. The klystron, designated the VKL-8301B, was ordered by DESY for the European XFEL. The klystron was designed using of sate-of-the-art multi-dimensional design codes to ensure that all performance requirements are exceeded. Initial rf hot test data at reduced duty and pulse width produced a peak saturated rf output power in excess of 11 MW and 70% efficiency, which was however accompanied by high beam interception. Operation at full duty and pulse width as well as adjustment of the focusing and retuning the cavity frequencies impacted output power and efficiency. A compromise was found to satisfy all required operating conditions, including operation into a higher output mismatch. Complete test results will be presented at the conference.

Design and operation of a high power, high efficiency, L-band multiple beam klystron

CPI's second generation, 10 MW, 1300 MHz multiple beam klystron (MBK), designated the VKL-8301B, has been developed and is being built for the European X-ray free electron laser (XFEL), which is under construction at DESY in Hamburg (Germany). At 10 MW peak rf output the MBK is required to provide at least 65% efficiency and more than 3 MHz instantaneous -1 dB bandwidth. Average power and rf pulse length are 150 kW and 1.5 ms, respectively. MBKs have the advantage of generating high rf output powers at moderate electron beam energies. For our design, six off-axis electron beams enable low cathode current density for longer cathode life. Compared to our first- generation design, where higher-order-mode cylindrical cavities were used, we are utilizing ring resonators operating in the fundamental-mode. This ensures sufficient beam separation while still keeping the overall diameter of the device small in order to reduce cost. Our in-house 1D large-signal rf code (LSCEX) was used to come up with the initial rf design. The 2.5D rf code TESLA enabled us to verify and refine the design. For the cavity design we utilized the commercially available 3D codes MAFIA and HFSS. The baseline beam optics design was created using our in-house 2.5D code XGun. With state-of- the-art 3D modeling software for beam optics (MICHELLE) and magnetics (MagNet) we then validated and optimized the design. Most of the mechanical design is completed. Material for the prototype is currently being procured and we will start building the klystron by the end of February 2008. We are going to present simulated data showing the expected performance of the device. The simulations exceed the requirements by a healthy margin. Measured data will be presented as they become available throughout the assembly process.

Development of a 1.3 GHz, 10 MW, 65% efficiency multi-beam klystron for XFEL

Large particle accelerator projects like the European X-ray Free Electron LASER (XFEL), which is under construction at DESY in Hamburg (Germany), or like the planned International Linear Collider (ILC) favor MBKs for their ability to generate high rf output powers at moderate electron beam energies. For the XFEL, Deutsches Electronen Synchrotron (DESY) ordered a prototype of a horizontally oriented, high-power MBK operating at 1300 MHz. This is CPGammas second generation 10 MW, L-band MBK, designated the VKL-8301B. The klystron is required to provide at least 65% efficiency at 10 MW peak rf output and more than 3 MHz instantaneous -l dB bandwidth. Average power and rf pulse length are 150 kW and 1.5 ms, respectively. Our design uses six off-axis electron beams for low cathode current density and thus longer cathode life. For the rf cavities we are utilizing fundamental-mode ring resonators. This ensures sufficient beam separation while still keeping the overall diameter of the device small in order to reduce cost. A more in-depth report on our design process and the tools we used was presented at the 2008 ICOPS. At the time of submission of this paper, initial rf hot test data were taken at reduced duty and pulse width while operating into well-matched output loads. At 0.42% rf duty, a peak rf output power as high as 11.2 MW was achieved, which corresponds to a 74% efficiency. The electron beam interception at and close to saturation was fairly high. Preliminary measurements of body power and the high efficiency indicate that mostly low-energy electrons past the output cavity gaps are involved in the klystron body interception in that operating condition. Initial optimization of the electromagnet for lower interception resulted in a 70% reduction of the rf body current, but this was accompanied by a noticeable drop in rf output power, efficiency (down to 67%) and gain. The klystron performance was stable for all operating conditions encountered so far. Further optimization of the magnetic field balance still has to be carried out for low body current and high efficiency at all required operating conditions, including operation into an output mismatch up to 1.2:1 VSWR. A more complete set of data taken after optimization and tuning will be presented at the conference.

Test results from a 1.3 GHZ, 10 MW, high efficiency multiple beam klystron for XFEL

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

E. Cesca

Author Tools

Chat about Author