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Design of a relativistic Klystron Two-Beam Accelerator Prototype

Description: We are designing an experiment to study physics, engineering, and costing issues of an extended Relativistic Klystron Two-Beam Accelerator (RK-TBA). The experiment is a prototype for an RK-TBA based microwave power source suitable for driving a 1 TeV linear collider. Major components of the experiment include a 2.5-MV, 1.5-kA electron source, a 11.4-GHz modulator, a bunch compressor, and a 8-m extraction section. The extraction section will be comprised of 4 traveling-wave output structures, each generating about 360 MW of rf power. Induction cells will be used in the extraction section to maintain the average beam energy at 5 MeV. Status of the design is presented.
Date: April 1, 1995
Creator: Westenskow, G.; Caporaso, G.; Chen, Y.; Houck, T.; Yu, S.; Chattopadhyay, S. et al.
Partner: UNT Libraries Government Documents Department

Towards a PEBB-Based Design Approach for a Marx-Topology ILC Klystron Modulator

Description: Introduced by the U.S. Navy more than a decade ago, the concept of Power Electronic Building Blocks (PEBBs) has been successfully applied in various applications. It is well accepted within the power electronics arena that this concept offers the potential to achieve increased levels of modularity and compactness. This approach is thus ideally suited for applications where easy serviceability and high availability are key, such as the ILC. This paper presents a building block approach for designing a Marx-topology ILC klystron modulator.
Date: October 17, 2009
Creator: Macken, K
Partner: UNT Libraries Government Documents Department

Final Report, IUT - B291527, January 1996 - March 1997

Description: The following note investigates scaling the 11.4-GHz TBNLC design of a relativistic klystron two-beam accelerator for a 30-GHz, 50-bunch accelerator design. We will refer to this point design as the RK-CLIC. We do not expect that the design will be optimal, but offer it as a starting point for discussions. In this memo, we begin with a general description of the RK-CLIC and drive beam dynamics, discuss required changes to major components, estimate the efficiency of wall plug to microwave power, and estimate costs. To be of interest the design must be such that it: (1) Can be installed at modest cost, (2) Operate with high wall plug to reconversion efficiency, and (3) Have acceptable drive beam dynamics.
Date: April 23, 1996
Creator: Henestroza, E.
Partner: UNT Libraries Government Documents Department

RF breakdown studies in X-Band klystron cavities

Description: RF breakdown studies are presently being carried out at SLAC with klystron cavities in a traveling wave resonator (TWR). Different kinds of fabrication methods and several kinds of semiconducting and insulating coatings have been applied to X-Band TM{sub 010} cavities. RF breakdown thresholds up to 250 MV/m have been obtained. Dark current levels were found to be depressed on TiN-coated and single-point diamond turned cavities. A new TM{sub 020} cavity with demountable electrodes has been designed and will be used to test a variety of materials, coatings, and processes. Recent tests of klystron output windows at 119 MW are also presented in this paper.
Date: May 1, 1997
Creator: Xu, X.; Callin, R.S. & Fowkes, W.R.
Partner: UNT Libraries Government Documents Department

PPM focused X-band klystron development at the Stanford Linear Accelerator Center

Description: X-band klystrons capable of 50 MW and utilizing Periodic Permanent Magnet (PPM) focusing are undergoing design and fabrication 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). The first klystron to be tested this year has a 0.6 microK beam at 465 kV, a 5 cells traveling wave output structure and a predicted efficiency of 63%. A 465 kV, 190 A beam stick with 12 periods of PPM focusing has recently operated to verify the gun optics and transmission of the beam in the absence of rf bunching. Beam transmission greater than 99.8% has been measured. Design and simulation of the beam stick and klystron are discussed, along with performance of the beam stick under confined flow and shielded conditions.
Date: July 1, 1996
Creator: Sprehn, D.; Caryotakis, G.; Eppley, K. & Phillips, R.M.
Partner: UNT Libraries Government Documents Department

Phase loop bandwidth measurements on the advanced photon source 352 MHz rf systems

Description: Phase loop bandwidth tests were performed on the Advanced Photon Source storage ring 352-MHz rf systems. These measurements were made using the HP3563A Control Systems Analyzer, with the rf systems running at 30 kilowatts into each of the storage ring cavities, without stored beam. An electronic phase shifter was used to inject approximately 14 degrees of stimulated phase shift into the low-level rf system, which produced measureable response voltage in the feedback loops without upsetting normal rf system operation. With the PID (proportional-integral-differential) amplifier settings at the values used during accelerator operation, the measurement data revealed that the 3-dB response for the cavity sum and klystron power-phase loops is approximately 7 kHz and 45 kHz, respectively, with the cavities the primary bandwidth-limiting factor in the cavity-sum loop. Data were taken at various PID settings until the loops became unstable. Crosstalk between the two phase loops was measured.
Date: August 1, 1997
Creator: Horan, D.; Nassiri, A. & Schwartz, C.
Partner: UNT Libraries Government Documents Department

Studies of beam dynamics in relativistic klystron two-beam accelerators

Description: Two-beam accelerators (TBAs) based upon free-electron lasers (FELs) or relativistic klystrons (RK-TBAs) have been proposed as efficient power sources for next generation high-energy linear colliders. Studies have demonstrated the possibility of building TBAs from X-band ({approximately}8-12 GHz) through Ka band ({approximately} 30-35 GHz) frequency regions. Provided that further prototyping shows stable beam propagation with minimal current loss and production of good quality, high-power rf fields, this technology is compatible with current schemes for electron-positron colliders in the multi-TeV center-of-mass scale. A new method of simulating the beam dynamics in accelerators of this type has been developed in this dissertation. There are three main components to this simulation. The first is a tracking algorithm to generate nonlinear transfer maps for pushing noninteracting particles through the external fields. The second component is a 3D Particle-In-Cell (PIC) algorithm that solves a set of Helmholtz equations for the self-fields, including the conducting boundary condition, and generates impulses that are interleaved with the nonlinear maps by means of a split-operation algorithm. The Helmholtz equations are solved by a multi-grid algorithm. The third component is an equivalent circuit equation solver that advances the modal rf cavity fields in time due to excitation by the modulated beam. The RTA project is described, and the simulation code is used to design the latter portions of the experiment. Detailed calculations of the beam dynamics and of the rf cavity output are presented and discussed. A beamline design is presented that will generate nearly 1.2 GW of power from 40 input, gain, and output rv cavities over a 10 m distance. The simulations show that beam current losses are acceptable, and that longitudinal and transverse focusing techniques are sufficient capable of maintaining a high degree of beam quality along the entire beamline. Additional experimental efforts are also described.
Date: November 1, 1999
Creator: Lidia, Steven M.
Partner: UNT Libraries Government Documents Department

Automatic Frequency Control of Microwave Radiation Sources

Description: Resonant cavity controlled klystron frequency stabilization circuits and quartz-crystal oscillator frequency stabilization circuits were investigated for reflex klystrons operating at frequencies in the X-band range. The crystal oscillator circuit employed achieved better than 2 parts in 10 in frequency stability. A test of the functional properties of the frequency standard was made using the Stark effect in molecules.
Date: August 1979
Creator: Payne, Bobby D.
Partner: UNT Libraries

Booster Synchrotron RF System Upgrade for SPEAR3

Description: Recent progress at the SPEAR3 includes the increase in stored current from 100 mA to 200 mA and top-off injection to allow beamlines to stay open during injection. Presently the booster injects 3.0 GeV beam to SPEAR3 three times a day. The stored beam decays to about 150 mA between the injections. The growing user demands are to increase the stored current to the design value of 500 mA, and to maintain it at a constant value within a percent or so. To achieve this goal the booster must inject once every few minutes. For improved injection efficiency, all RF systems at the linac, booster and SPEAR3 need to be phase-locked. The present booster RF system is basically a copy of the SPEAR2 RF system with 358.5 MHz and 40 kW peak RF power driving a 5-cell RF cavity for 1.0 MV gap voltage. These requirements entail a booster RF system upgrade to a scaled down version of the SPEAR3 RF system of 476.3 MHz with 1.2 MW cw klystron output power capabilities. We will analyze each subsystem option for their merits within budgetary and geometric space constraints. A substantial portion of the system will come from the decommissioned PEP-II RF stations.
Date: July 6, 2012
Creator: Park, Sanghyun; /SLAC; Corbett, Jeff & /SLAC
Partner: UNT Libraries Government Documents Department

CONCEPTUAL DESIGN OF A BRIGHT ELECTRON INJECTOR BASED ON A LASER-DRIVEN PHOTOCATHODE RF ELECTRON GUN

Description: Conceptual design of a bright electron injector for the 1 GeV high gradient test experiment. envisaged by the LLNL-SLAC-LBL collaboration on the Relativistic Klystron is presented. The design utilizes a high-brightness laser-driven RF photocathode electron gun, similar to the pioneering LANL early studies in concept (different parametrically however), together with achromatic magnetic bunching and transport systems and diagnostics. The design is performed with attention to possible use in an FEL as well. A simple but realistic analytic model including longitudinal and transverse space-charge and RF effects and extensive computer simulation form the basis of the parametric choice for the source. These parameters are used as guides for the design of the pico-second laser system and magnetic bunching section.
Date: September 1, 1988
Creator: Chattopadhyay, S.; Chen, Y.J.; Hopkins, D.; Kim, K.J.; Kung, A.; Miller, R. et al.
Partner: UNT Libraries Government Documents Department

Accelerator Simulation and Operation Via. Identical Operational Interfaces

Description: The CEBAF accelerator contains approximately 2500 power supplies, 340 klystrons, and 800 beam monitors. The operation of such a complex machine requires a control system which can provide a high degree of automation with strong support by simulation and modeling programs.\nWe present the architecture and first results of a control system which allows one the use of identical operation procedures and interfaces for operation of the real accelerator and high-level accelerator simulation programs. The interfaces were developed using TACL (Thaumaturgic Automated Control Logic) control software, developed at CEBAF for accelerator control. This setup provides the capability to: (1) test and debug the various operation procedures before the completion of the accelerator, (2) execute machine simulations under realistic environmental conditions, and (3) preview and evaluate the effectiveness of operational procedures during run time. The optimized simulation program adds only two seconds to
Date: May 1, 1991
Creator: Barry, Andrea; Bowling, Bruce; Lahti, George; Sage, Joan; Tang, Johnny; Kewisch, Jorg et al.
Partner: UNT Libraries Government Documents Department

Multi-MW K-Band 7th Harmonic Multiplier for High-Gradient Accelerator R&D

Description: A preliminary design and current status are presented for a two-cavity 7th harmonic multiplier, intended as a high-power RF source for use in experiments aimed at developing high-gradient structures for a future collider. The harmonic multiplier is to produce power in K-band using as its RF driver an XK-5 S-band klystron (2.856 GHz). The multiplier is to be built with a TE{sub 111} rotating mode input cavity and interchangeable output cavities, a principal example being a TE{sub 711} rotating mode cavity running at 20 GHz. The design that is described uses a 250 kV, 20 A injected laminar electron beam. With 8.5 MW of S-band drive power, 4.4 MW of 20-GHz output power is predicted. The design uses a gun, magnetic coils, and beam collector from an existing waveguide 7th harmonic multiplier. The gun has been re-conditioned and the desired operating parameters have been achieved.
Date: May 1, 2009
Creator: Solyak, N.A.; Yakovlev, V.P.; /Omega-P, New Haven /Fermilab; Hirschfield, J.L.; /Omega-P, New Haven /Yale U.; Kazakevich, G.M. et al.
Partner: UNT Libraries Government Documents Department

Design Considerations for a PEBB-Based Marx-Topology ILC Klystron Modulator

Description: The concept of Power Electronic Building Blocks (PEBBs) has its origin in the U.S. Navy during the last decade of the past century. As compared to a more conventional or classical design approach, a PEBB-oriented design approach combines various potential advantages such as increased modularity, high availability and simplified serviceability. This relatively new design paradigm for power conversion has progressively matured since then and its underlying philosophy has been clearly and successfully demonstrated in a number of real-world applications. Therefore, this approach has been adopted here to design a Marx-topology modulator for an International Linear Collider (ILC) environment where easy serviceability and high availability are crucial. This paper describes various aspects relating to the design of a 32-cell Marx-topology ILC klystron modulator. The concept of nested droop correction is introduced and illustrated. Several design considerations including cosmic ray withstand, power cycling capability, fault tolerance, etc., are discussed. Details of the design of a Marx cell PEBB are included.
Date: December 9, 2009
Creator: Macken, K.; Beukers, T.; Burkhart, C.; Kemp, M.A.; Nguyen, M.N.; Tang, T. et al.
Partner: UNT Libraries Government Documents Department

Analysis of DESY-Flash LLRF Measurements for the ILC Heavy Beam Loading Test

Description: In September 2008 the DESY-FLASH accelerator was run with up to 550, 3 nano-coulomb bunches at 5 Hz repetition rate. This test is part of a longer-term study aimed at validating ILC parameters by operation as close as possible to ILC beam currents and RF gradients. The present paper reports on the analysis that has been done in order to understand the RF control system performance during this test. Actual klystron power requirements and beam stability are evaluated with heavy beam loading conditions. Results include suggested improvements for upcoming tests in 2009.
Date: June 1, 2009
Creator: Cancelo, Gustavo; Chase, Brian; Davidsaver, Michael; /Fermilab; Carwardine, J.; /Argonne et al.
Partner: UNT Libraries Government Documents Department

The SNS linac high power RF system design, status, and results

Description: The Spallation Neutron Source being built at the Oak Ridge National Lab in Tennessee requires a 1 GeV proton linac. Los Alamos has responsibility for the RF systems for the entire linac. The linac requires 3 distinct types of RF systems: 2.5-MW peak, 402.5 MHz, RF systems for the RFQ and DTL (7 systems total); 5-MW peak, 805 MHz systems for the CCL and the two energy corrector cavities (6 systems total); and 550-kW peak, 805 MHz systems for the superconducting sections (8 1 systems total). The design of the SNS Linac RF system was presented at the 2001 Particle Accelerator Conference in Chicago. Vendors have been selected for the klystrons (3 different vendors), circulators ( I vendor), transmitter (1 vendor), and high power RF loads (3 different vendors). This paper presents the results and status of vendor procurements, test results of the major components of the Linac RF system and our installation progress.
Date: January 1, 2003
Creator: Rees, D. E. (Daniel E.); Bradley, J. T. (Joseph T.), III; Cummings, K. A. (Karen Ann); Hardek, T. W. (Thomas W.); Roybal, W. T. (William T.) & Tallerico, P. J. (Paul J.)
Partner: UNT Libraries Government Documents Department

AVAILABILITY MODEL FOR THE SNS LINAC RF SYSTEM

Description: The Linac RF system is broken down into eight major components for this model. These components are: the klystrons, the waveguide, the water loads, the circulators, the converter/modulator, the transmitter, the window, and the low level RF (LLRF) controls. The mean time between failures (MTBF) for several of the components vary with voltage or klystron power level, and this variation is discussed below. In general, these MTBF's are design requirements supplied to the vendors of the subsystems, and verified at design reviews and by the experience at other accelerators. We assume that the scheduled operational time for the SNS is 6000 hours per year, and use this number to calculate the availability. We have to calculate the total down time during the 6000 hours of operation, and the availability is defined as one minus the unexpected down time for the year, divided by the number of operating hours in the year. Ideally, we would use distributions of MTBF's and MTTR's, since each failure will be different, but the equipment is not yet built, so the distributions are not available, and we make the assumption of constant MTBF and MTTR.
Date: January 1, 2001
Creator: Tallerico, P. J. (Paul J.); Rees, D. E. (Daniel E.) & Anderson, D. E. (David E.)
Partner: UNT Libraries Government Documents Department

Sheet Beam Klystron Instability Analysis

Description: Using the principle of energy balance we develop a 2D theory for calculating growth rates of instability in a two-cavity model of a sheet beam klystron. An important ingredient is a TE-like mode in the gap that also gives a longitudinal kick to the beam. When compared with a self-consistent particle-in-cell calculation, with sheet beam klystron-type parameters, agreement is quite good up to half the design current, 65 A; at full current, however, other, current-dependent effects come in and the results deviate significantly.
Date: May 8, 2009
Creator: Bane, K.L.F.; Jensen, A.; Li, Z.; Stupakov, G.; Adolphsen, C. & /SLAC
Partner: UNT Libraries Government Documents Department

A Vernier Regulator for ILC Marx Droop Compensation

Description: A two-part compensation scheme, Vernier Regulation, has been applied to offset the voltage droop (40% without correction) in a Marx-topology klystron modulator developed for the International Linear Collider (ILC). Coarse regulation, {+-}5%, is achieved by turning on additional Main Marx cells (Delayed Cells) sequentially as the droop reaches the cell voltage (11 kV). Further regulation to {+-}0.5% is achieved by adding a small Marx in series with the Main Marx. This Vernier Marx is composed of sixteen, 1.2 kV cells that are assembled as a seventeenth cell in the Main Marx. These Vernier Cells are turned on sequentially to generate a series of discrete corrections to the droop in the Main Marx cells with a step size {le}1% of the output voltage. As the required correction reaches 11 kV, all Vernier Cells are turned off synchronously with the turn on of a Delayed Cell. There are up to five Delayed Cells and six Vernier Marx cycles during each ILC Marx output pulse. The Vernier Marx has a local control system that will detect and respond to over-voltage and over-current errors. In this paper, a detailed description of the design, implementation and testing of the Vernier Marx is presented.
Date: October 30, 2009
Creator: Tang, Tao
Partner: UNT Libraries Government Documents Department