摘要:

In this paper we discuss a new approach to two-beam acceleration. The energy for RF production is initially stored in a long-pulse electron beam which is efficiently accelerated to about 1.2 GeV by a fully loaded, conventional, low frequency (∼1 GHz) linac. The beam pulse length is twice the length of the high-gradient linac. Segments of this long pulse beam are compressed using combiner rings to create a sequence of higher peak power drive beams with gaps in between. This train of drive beams is distributed from the end of the linac against the main beam direction down a common transport line so that each drive beam can power a section of the main linac. After a 180-degree turn, each high-current, low-energy drive beam is decelerated in low-impedance decelerator structures, and the resulting power is used to accelerate the low-current, high-energy beam in the main linac. The method discussed here seems relatively inexpensive, is very flexible and can be used to accelerate beams for linear colliders over the entire frequency and energy range. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.59012

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

The technical challenge for making two-beam accelerators into realizable power sources for high-energy colliders lies in the creation of the drive beam and in its propagation over long distances through multiple extraction sections. This year we have been constructing a 1.2-kA, 1-MeV, induction gun for a prototype relativistic klystron two-beam accelerator (RK-TBA). The electron source will be a 8.9 cm diameter, thermionic, flat-surface cathode with a maximum shroud field stress of approximately 165 kV/cm. Additional design parameters for the injector include a pulse length of over 150-ns flat top (1&percent; energy variation), and a normalized edge emittance of less than 300 pi-mm-mr. The prototype accelerator will be used to study, physics, engineering, and costing issues involved in the application of the RK-TBA concept to linear colliders. We have also been studying optimization parameters, such as frequency, for the application of the RK-TBA concept to multi-TeV linear colliders. As an rf power source the RK-TBA scales favorably up to frequencies around 35 GHz. An overview of this work with details of the design and performance of the prototype injector, beam line, and diagnostics will be presented. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.59005

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

The Compact Linear Collider (CLIC) Test Facility (CTF II) at CERN has recently demonstrated Two-Beam power production and acceleration at 30 GHz. With 41 MW of 30 GHz power produced in 14 ns pulses at a repetition rate of 5 Hz, the main beam has been accelerated by 28 MeV. The 30 GHz RF power is extracted in low impedance decelerating structures from a low-energy, high-current “drive beam” which runs parallel to the main beam. The average current in the drive-beam train is 25 A, while the peak current exceeds 2 kA. Crosschecks between measured drive-beam charge, 30 GHz power and main-beam energy gain are in good agreement. In this paper, some relevant experimental and technical issues on drive-beam generation, two-beam power production and acceleration are presented. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.59015

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

The Stanford Linear Accelerator Center (SLAC) klystron group is currently designing, fabricating and testing 11.424 GHz klystrons with peak output powers from 50 to 75 MW at 1 to 2 &mgr;s rf pulsewidths as part of an effort to realize components necessary for the construction of the Next Linear Collider (NLC). In order to eliminate the projected operational-year energy bill for klystron solenoids, Periodic Permanent Magnet (PPM) focusing has been employed on our latest X-band klystron designs. A PPM beam tester has operated at the same repetition rate, voltage and average beam power required for a 75-MW NLC klystron. Prototype 50 and 75-MW PPM klystrons were built and tested during 1996 and 1997 which operate from 50 to 70 MW at efficiencies greater than 55&percent;. Construction and testing of 75-MW research klystrons will continue while the design and reliability is perfected. This paper will discuss the design of these PPM klystrons and the results of testing to date along with future plans for the development of a low-cost Design for Manufacture (DFM) 75-MW klystron and invitation for industry participation. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.59036

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

We report on three electron gun projects that are aimed at power tube and injector applications. The purpose of the work is to develop robust electron guns which produce self-bunched, high-current-density beams. We have demonstrated, in a microwave cavity, self-bunching, cold electron emission, long life, and tolerance to contamination. The cold process is based on secondary electron emission. FMT has studied using simulation codes the resonant bunching process which gives rise to high current densities (0.01–5 kA/cm2), high charge bunches (up to 500 nC/bunch), and short pulses (1–100 ps) for frequencies from 1 to 12 GHz. The beam pulse width is nominally ∼5&percent; of therfperiod. The first project is the L-Band Micro-Pulse Gun (MPG). Measurements show ∼40 ps long micro-bunches at ∼20 A/cm2without contamination due to air exposure. Lifetime testing has been carried out for about 18 months operating at 1.25 GHz for almost 24 hours per day at a repetition rate of 300 Hz and 5 &mgr;s-long macro-pulses. Approximately5.8×1013micro-bunches or 62,000 coulombs have passed through this gun and it is still working fine. The second project, the S-Band MPG, is now operational. It is functioning at a frequency of 2.85 GHz, a repetition rate of 30 Hz, with a 2 &mgr;s-long macro-pulse. It produces about 45 A in the macro-pulse. The third project is a 34.2 GHz frequency-multiplied source driven by an X-Band MPG. A point design was performed at anrfoutput power of 150 MW at 34.2 GHz. The resulting system efficiency is 53&percent; and the gain is 60 dB. The system efficiency includes the input cavity efficiency, input driver efficiency (a 50 MW klystron at 11.4 GHz), output cavity efficiency, and the post-acceleration efficiency. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.59030

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

In the present paper, the experimental test results of the klystron with a PPM focusing system manufactured in the Branch of INP (Protvino, Russia) in collaboration with KEK (Japan), are presented. The design pulse voltage in the klystron was 550 kV at the beam microperveance 0.93 and operating frequency 11.424 GHz. In the experiments, the output RF power of 77 MW was achieved. The results of the numerical simulations of the klystron and their comparison with those of the klystron tests in KEK are discussed. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.59032

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

The development of W-band klystrons is discussed. Modeling of the klystron performance predicts 100 kW output power from a single klystron. The permanent magnet focusing and small size of the circuit permit combination of multiple klystrons in a module. A six-klystron module in a single vacuum envelope is expected to produce 500 kW peak power and up to 5 kW average power. The critical issues in the W-band klystron development are the electron beam transport and the fabrication of the klystron circuit. Two microfabrication techniques, EDM and LIGA, are being evaluated to produce the W-band circuit. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.59033

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

With the development of ever higher energy particle accelerators comes the need for compactness and high gradient, which in turn require very high frequency high power rf sources. Recent development work in W-band accelerating techniques has spurred the development of a high-power W-band source. Axisymmetric sources suffer from fundamental power output limitations(Psat∼&lgr;2)brought on by the conflicting requirements of small beam sizes and high beam current. The sheet beam klystron allows for an increase in beam current without substantial increase in the beam current density, allowing for reduced cathode current densities and focussing field strengths. Initial simulations of a 20:1 aspect ratio sheet beam/cavity interaction using the 3 dimensional particle-in-cell code Magic3D have demonstrated a 35&percent; beam-power to RF power extraction efficiency. Calculational work and numerical simulations leading to a prototype W-band sheet beam klystron will be presented, together with preliminary cold test structure studies of a proposed RF cavity geometry. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.59037

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

The Multiple Beam Klystron (MBK) is really exploited in the USSR only. In recent years, there has arisen interest in the other countries. At present, the MBK with fundamental mode cavities are predominate, recently there is renewed interest in more complicated schemes. The advantages of MBK for the designer are low individual beam perveance, together with low total electron stream resistance and high total power. That helps obtain the high electronic and circuit efficiency and contributes to high gain, all of which are very important for broadening of instantaneous operating band. Of course, the MBK creates some difficulties for the designer. They are the non-uniformity of cavity rf field distribution and the transverse contributions of focusing magnetic field. There are remedies, but they lead to some complications. The broadening of instantaneous operating band requires tight drift channels packing, and also klystron life depends strongly on cathode-state-of-the-art. In spite of these difficulties, we have very successful low-voltage MBKs for various radar and communication applications in the frequency ranges from 1 to 10 GHz, with high peak and average power, and bandwidths up to 5–10&percent;. In Russia today, single-beam klystrons are limited primarily to the mm-range. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.59034

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.59000

出版商:AIP    

年代:1999

数据来源: AIP