摘要:

The TESLA project proposed by the TESLA collaboration in 2001 is a 500 to 800GeV e+/e− linear collider with integrated free electron laser facility. The accelerator is based on superconducting cavity technology. Approximately 20000 superconducting cavities operated at 1.3GHz with a gradient of 23.4MV/m or 35MV/m will be required to achieve the energy of 500GeV or 800GeV respectively. For 500GeV ∼600 RF stations each generating 10MW of RF power at 1.3GHz at a pulse duration of 1.37ms and a repetition rate of 5 or 10Hz are required. The original TESLA design was modified in 2002 and now includes a dedicated 20GeV electron accelerator in a separate tunnel for free electron laser application. The TESLA XFEL will provide XFEL radiation of unprecedented peak brilliance and full transverse coherence in the wavelength range of 0.1 to 6.4nm at a pulse duration of 100fs. The technology of both accelerators, the TESLA linear collider and the XFEL, will be identical, however the number of superconducting cavities and RF stations for the XFEL will be reduced to 936 and 26 respectively. This paper describes the layout of the entire RF system of the TESLA linear collider and the TESLA XFEL and gives an overview of its various subsystems and components. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635096

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

X‐band klystrons capable of 75 MW and utilizing either solenoidal or Periodic Permanent Magnet (PPM) focusing are undergoing design, fabrication and testing at the Stanford Linear Accelerator Center (SLAC). The klystron development is part of an effort to realize components necessary for the construction of the Next Linear Collider (NLC). SLAC has developed a solenoidal‐focused X‐band klystron which is currently the workhorse of high power component testing for the NLC. A state‐of‐the‐art modulator will drive eight of these tubes which, in turn, will power an rf distribution system referred to as the “8‐pack” in order to test these modulators and waveguide components. Eventually, in an interest to save millions of dollars per year in the operational cost of the NLC, these tubes will be replaced by PPM klystrons. 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. These tubes follow from the successful 50 MW PPM design of 1996. Recent testing of this particular tube at wider pulsewidths has reached 50 MW at 55 &percent; efficiency, 2.4 &mgr;s and 60 Hz. Two 50 MW PPM klystrons produced by industry have been delivered to SLAC. One of these devices arrived with a vacuum suitable for test. Testing during 2001 revealed a serious, but curious, vacuum response which limited the operation to an rf output of ∼40 MW. A 75 MW PPM klystron prototype was first constructed in 1997 and later modified in 1999 to eliminate oscillations. This tube has reached the NLC design target of 75 MW at 1.5 &mgr;s though at a significantly reduced rep rate. Two new 75 MW PPM klystrons were constructed and tested in 2002 after a diode was successfully tested in 2001. The new design was aimed at reducing the cost and increasing the reliability of such high‐energy devices. The rf circuit and beam focusing for one of these devices was built by industry and incorporated into one of the tubes. Both of these latest devices suffered from a variety of issues concerning gun stability, beam confinement and rf stability. A rebuilt version of this latest design was constructed in early 2003 and completed testing in June. The performance of these various klystrons, particularly during 2002 and 2003, will be presented along with results of studies pertinent to their construction. Design and manufacturing issues of the various klystrons are discussed, along with plans for future modifications and areas of research. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635097

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The current baseline design for the 500‐GeV SLAC/KEK future collider requires approximately 5000 75‐MW, 1.6 &mgr;s, PPM pencil‐beam klystrons. A prototype is currently on test. Although the estimated cost of the klystrons is a small part of the total collider cost, this number of klystrons is at least an order of magnitude higher than the klystron population in any scientific or military system ever fielded. A back‐up sheet‐beam klystron design has been under study at SLAC for the last six years. It offers several advantages: If two sheet beams were employed in parallel, the current density at the two cathodes would be low, and the power density at the output cavity a fraction of that in the pencil‐beam klystron. Furthermore, because of significantly fewer vacuum parts, the 150‐MW SBK should have a substantially lower cost than the baseline 75‐MW pencil‐beam klystron. Finally, it is considered that because of the lower power density, a longer rf pulse (3.2 &mgr;s) could be employed. All this means is that, with more pulse compression, the total number of klystrons in the collider could be reduced by a factor of 4, to approximately 1250. The total cost of the klystrons would be cut by an even larger factor. Since a practical SBK has never been designed before, two major problems had to be solved before a meaningful computer simulation of the entire tube could be performed. First, a sheet‐beam gun had to be designed, along with a periodically‐focused beam transport system outside the vacuum. Secondly, since extended interaction cavities are used throughout, new techniques had to be developed to provide useful designs with adequate stability and mode separation. This work is essentially complete. The work to parallel 24 CPUs, and modify the MAGIC 3D code so simulations of the complete SBK can be performed in a reasonable time, has progressed sufficiently for an interim report on the project to be presented. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635098

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

After five years of operation, the 17 GHz MKII relativistic klystron in service at the MIT Plasma Science and Fusion Center was upgraded with a new output structure to provide a common source of high peak power for continuing operation of the 17 GHz linac, for RF gun testing and for energizing a recently developed circularly polarized beam deflection RF system to evaluate the ultra short electron bunch performance of the linac. The salient features of the impedance and phase velocity tapered new traveling wave output structure designed for high gain and stability are described; and initial high power test results of the 17 GHz relativistic klystron are presented. The output structure was designed as a beam driven bunching and phase shifting 2&pgr;/3 mode circuit using codes that were developed over a 40 year period designing, fabricating and testing high current traveling wave linac bunchers. The electrical length of the new (MKIII) output circuit was extended to 1200 degrees using a group to phase velocity harmonic mean ratio of 0.124 to provide total skin losses of less than 5 percent and a phase/frequency sensitivity of only 0.6 degree/MHz. A dual feed racetrack shaped output cavity having a decelerating gradient of 150 kV/cm and beam apertures substantially larger than &lgr;0/2, to allow reduction of space charge debunching forces, are added advantages of this 25 MW, 71 dB gain RF amplifier. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635099

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Advanced research continues in the field of High Power Microwaves (HPM), which have potential applications ranging from long distance communications, radar, environmental waste clean up, bio‐toxin neutralization, fusion heating, as well as a host of others. Current HPM sources being studied are the Magnetically Insulated Line Oscillator, Relativistic Klystron Oscillator, and Relativistic Magnetron, and experimental and computational comparisons will be presented. Relevant components to be discussed are recent cathode results, recent antenna results, as well as the discussion of a HPM air breakdown experiment to be conducted in the near future. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635100

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The uplink transmitters of the Deep Space Network (DSN) perform three key functions in support of space missions: navigation, command uplink, and emergency recovery. The transmitters range in frequency from S‐band to Ka‐band, and range in RF transmit power from 200W to 400kW. Future improvements to the uplink transmitters will focus on higher frequency transmitters for high data rate communications, high power X‐band uplinks for emergency recovery, and/or in‐phase uplink arraying for either application. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635101

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

There is presented a comparative analysis of MBK and TWT parameters, and their influence on the spectrum of functions, which each of the devices is best suited to fulfill. Devices of different power level (from hundreds of watts to hundreds of kilowatts) and frequency range (from units to tenth of GHz) are analyzed. Most decisive parameters, namely, the cathode and control voltages, efficiency, the amplification frequency band, the noises, harmonic and spurious oscillation parameters, the sensitivity to voltage instabilities, and the mass and dimensions of the devices are considered. In specific fields of operation the vibration‐proof parameters of the device is also of great importance. Interrelations between some of the devices’ parameters and the parameters of radio — electronic systems are discussed. Main requirements are mentioned, which power amplifiers have to meet to satisfy the demands of different types of modern radio‐electronic systems. The degree of satisfying these demands by MBKs and TWTs determine the preferable fields of their application. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635102

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The design of an eight‐beam, four‐cavity multiple‐beam klystron (MBK) to be operated inS‐band is presented. The design methodologies for the gun, magnetic circuit, and RF interaction circuit are described, along with a brief description of the principal computational design tools. The large‐signal code, TESLA, was used to design the interaction circuit and is shown to be in excellent agreement with the three‐dimensional particle‐in‐cell code, MAGIC 3‐D. Computational simulations indicate that the optimized design has very low beam interception, producing a peak RF power of 865 kW with a corresponding gain of 34.5 dB and an electronic efficiency of ∼60&percent; at mid‐band (3.27 GHz). © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635103

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

At the University of Maryland, we have been developing high‐power coaxial gyroklystrons. Our present work is focused on the development of a 17.136 GHz four‐cavity frequency‐doubling gyroklystron amplifier. This device will then be used to drive a high gradient linear accelerator structure recently developed by the Haimson Corporation. Our work has been afflicted by many technical challenges, most arising from thermal imperfections in the custom‐made high current emitter of our electron gun. In our latest experimental run, instabilities were detected in the input cavity of our amplifier tube. These instabilities appear when the beam pitch ratio (&agr;) is approximately 1, thus impeding our search of domains with higher &agr; values (note that the circuit was designed to operate at &agr;=1.4). In order to remedy this problem, we have radically redesigned the input cavity, changing both its geometry and Q factor. The new input cavity has been fabricated and cold‐tested. It will soon undergo hot‐test in the next run of experimental studies of the circuit, which will commence after an upgrade of our vacuum system. Here we present the current status of this research. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635104

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

A high efficiency, high power magnicon at 34.272 GHz has been designed and built as a microwave source to develop RF technology for a future multi‐TeV electron‐positron linear collider. To develop this technology, this new RF source is being perfected for necessary tests of accelerating structures, RF pulse compressors, RF components, and to determine limits of breakdown and metal fatigue. After preliminary RF conditioning of only about 2×105pulses at reduced beam voltage and pulse width, the magnicon produced an output power at 34.3 GHz of 10.5 MW in 0.25 &mgr;s pulses, with a gain of 54 dB. Slotted line measurements confirmed that the output was monochromatic to within a margin of at least 30 dB. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1635105

出版商:AIP    

年代:1903

数据来源: AIP