Do you design and build vacuum electron devices, or work with the systems that use them? Quickly develop a solid understanding of how these devices work with this authoritative guide, written by an author with over fifty years of experience in the field. Rigorous in its approach, it focuses on the theory and design of commercially significant types of gridded, linear-beam, crossed-field and fast-wave tubes. Essential components such as waveguides, resonators, slow-wave structures, electron guns, beams, magnets and collectors are also covered, as well as the integration and reliable operation of devices in microwave and RF systems. Complex mathematical analysis is kept to a minimum, and Mathcad worksheets supporting the book online aid understanding of key concepts and connect the theory with practice. Including coverage of primary sources and current research trends, this is essential reading for researchers, practitioners and graduate students working on vacuum electron devices.

Microwave and RF Vacuum Electronic Power Sources

This is Part I of a two-part report on design and manufacturing methods used at SLAC to produce accelerator klystrons. Chapter 1 begins with the history and applications for klystrons, in both of which Stanford University was extensively involved. The remaining chapters review the theory of klystron operation, derive the principal formulae used in their design, and discuss the assumptions that they involve. These formulae are subsequently used in small-signal calculations of the frequency response of a particular klystron, whose performance is also simulated by two different computer codes. The results of calculations and simulations are compared to the actual performance of the klystron.

/pdf/high-power-klystrons-theory-and-practice-at-the-stanford-4pi6u2u4uw.pdf

High Power Klystrons: Theory and Practice at the Stanford Linear Accelerator CenterPart I

Over the last decades, the performance disparity between processor and memory has steadily grown in computer systems, an issue commonly known as Memory Wall (WULF; MCKEE, 1995). Since Dynamic Random-Access Memory (DRAM) is the most common type of main memory in computer systems, intense research efforts have been made to improve its performance and energy efficiency. However, DRAM design space exploration comes with problems. Although cycle-accurate memory simulators can simulate timings in a very precise manner, the simulation can become extremely slow. By moving to a higher abstraction level, through the virtual prototyping method, simulation speedup can be achieved with negligible losses in accuracy. Seeing that the DRAM memory controller is a key block for the overall memory system performance, it is integrated onto the same chip of the multiple CPU cores that require access to the off-chip main memory. Therefore, in this work, schedulers of the DRAM controller were modeled with SystemC/TLM 2.0 (IEEE Computer Society, 2012) in DRAMSys (JUNG M.; WEIS; WEHN, 2015), a flexible DRAM subsystem design space exploration framework. The DRAMSys restructuring was the main technical contribution of this work. Then, the controller was simulated with different scheduling mechanisms in order to better understand the memory system bottlenecks and to investigate which scheduler provides the best compromise between characteristics, such as bandwidth, thread-fairness and energy consumption.

Early Childhood Educators' Perceptions of the use of documentation in emergent programs: issues, benefits, barriers and questions

In the mid-1990’ s, groups at SLAC and KEK began dedicated development of X-band (11.4 GHz) rf technology for a next generation, TeV-scale linear collider. The choice of a relatively high frequency, four times that of the SLAC 50 GeV Linac, was motivated by the cost benefits of having lower rf energy per pulse (hence fewer rf sources) and reasonable efficiencies at high gradients (hence shorter linacs). To realize such savings, however, requires operation at gradients and peak powers much higher than that hitherto achieved. During the past twelve years, these challenges were met through innovations on several fronts. This paper reviews these achievements, which include developments in the generation and transport of high power rf, and new insights into high gradient limitations.

/pdf/advances-in-normal-conducting-accelerator-technology-from-3u99zz6yda.pdf

Advances in Normal Conducting Accelerator Technology from the X-Band Linear Collider Program

This paper reports the research work of an X-band sheet beam klystron with the aim of principle verification, which is fulfilled at the Institute of Electronics, Chinese Academy of Sciences. This paper includes two phases. The first phase is planned to build the sheet beam electron optics prototype tube using the closed periodically cusped magnetic focusing. The measured data shows that the rectangular beam with the cross section of 50 mm × 4 mm can propagate through ~ 300 mm from the cathode surface to the collector with the transmission of 92.4% at the voltage of 110 kV. This foregoing work successfully solves the beam formation and transportation and becomes the basis for developing the sheet beam klystron. In the second phase, the high-frequency interaction structure is designed and cold tested. The X-band sheet beam klystron is constructed and hot tested in the full voltage. The amplification characteristic can be observed near the voltage of 125 kV. For the drive power of 0.71 kW and the working frequency of 11.69 GHz, the output power of 2.8 MW is achieved with the 3 dB bandwidth of 30 MHz, and, correspondingly, the gain and the efficiency are 35.96 dB and 32.52%, respectively. At the same time, the beam transmission is 73.3%. An over 93% transmission is realized at the voltage of 135 kV, whereas the oscillation occurs in the tube. This research exhibits that the sheet beam klystron is a promising device for the high-power applications, whereas seeking the measures to overcome the oscillation is still an arduous task in the future.

Researches on an $X$ -Band Sheet Beam Klystron

Klystrons capable of 75 MW output power at 11.4 GHz have been under development at SLAC for the last decade. The work has been part of the program to realize all the components necessary for the construction of the Next Linear Collider (NLC). The effort has produced a family of solenoid-focused 50 MW klystrons, which are currently powering a 0.5 GeV test accelerator at SLAC and several test stands, where high power components are evaluated and fundamental research is performed studying rf breakdown and dark current production. Continuing development has resulted in a Periodic Permanent Magnet (PPM) focused 50 MW klystron, tested at SLAC and subsequently contracted for manufacture by industry in England and Japan. A 75 MW version of that PPM klystron was built at SLAC and reached 75 MW, with 2.8 microsecond pulses. Based on this design, a prototype 75 MW klystron, designed for low-cost manufacture, is currently under development at SLAC, and will eventually be procured from industry in modest quantities for advanced NLC tests. Beyond these developments, the design of Multiple Beam Klystrons (MBKs) is under study at SLAC. MBKs offer the possibility of considerably lower modulator costs by producing comparable power to the klystrons now available, at much lower voltages. 
* This work supported by the Department of Energy under contract DE-AC03-76SF00515

The Next Linear Collider Klystron Development Program

Klystrons capable of driving accelerator sections in the Next Linear Collider (NLC) have been developed at SLAC during the last decade. In addition to fourteen 50 MW solenoid-focused devices and a 50 MW Periodic Permanent Magnet focused (PPM) klystron, a 500 kV 75 MW PPM klystron was tested in 1999 to 80 MW with 3 µs pulses, but very low duty. Subsequent 75 MW prototypes aimed for low-cost manufacture by employing reusable focusing structures external to the vacuum, similar to a solenoid electromagnet. During the PPM klystron development, several partners (CPI, EEV and Toshiba) have participated by constructing partial or complete PPM klystrons. After early failures during testing of the first two devices, SLAC has recently tested this design (XP3-3) to the full NLC specifications of 75 MW, 1.6 µs pulse length, and 120 Hz. This 14.4 kW average power operation came with an efficiency of 50%. The XP3-3 average and peak output power, together with the focusing method, arguably makes it the most advanced high power klystron ever built anywhere in the world. Design considerations and test results for these latest prototypes will be presented.

/pdf/current-status-of-the-next-linear-collider-x-band-klystron-4uinl3x1ac.pdf

Current status of the next linear collider x-band klystron development program *

75 MW X-band klystrons utilizing Periodic Permanent Magnet (PPM) focusing have been undergoing design, fabrication and testing at the Stanford Linear Accelerator Center (SLAC) for almost nine years. The klystron development has been geared toward realizing the necessary components for the construction of the Next Linear Collider (NLC). The PPM devices built to date which fit this class of operation consist of a variety of 50 MW and 75 MW devices constructed by SLAC, KEK (Tsukuba, Japan) and industry. All these tubes follow from the successful SLAC design of a 50 MW PPM klystron in 1996. In 2004 the latest two klystrons were constructed and tested with preliminary results reported at EPAC2004. The first of these two devices was tested to the full NLC specifications of 75 MW, 1.6 microseconds pulse length, and 120 Hz. This 14.4 kW average power operation came with a tube efficiency >50%. The most recent testing of these last two devices will be presented here. Design and manufacturing issues of the latest klystron, due to be tested by the Fall of 2005, are also discussed.

/pdf/latest-results-in-slac-75-mw-ppm-klystrons-4squ5tc0wf.pdf

D. Sprehn

Papers

The Next Linear Collider Klystron Development Program

Current status of the next linear collider x-band klystron development program *

Latest Results in SLAC 75 MW PPM Klystrons