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Design Guidelines of a Double-Gap Microwave Rebuncher Cavity for a 400 MHz, 2.5 MeV Energy Light Ion Accelerator with Lower Gap Voltage and Field
A detailed electromagnetic model of a double-gap microwave rebuncher cavity proposed for 400-MHz, 2.5 MeV energy of the front end section in 1 GeV energy H- ion linear accelerator, is presented and validated by extensive simulations. This design is intended to decrease both the utilized gap voltage and peak electric field of the rebunching cavity, henceforth may decrease X-ray radiation. A low cos...Show More
Feasibility of Folded and Double Dipole Radio Frequency Quadrupole (RFQ) Cavities for Particle Accelerators
The quadrupole and dipole modes frequencies can be very close in a long four-vane RFQ as structure length increases. This requires extra mode stabilizer design to improve field stability, which may add to system complexity and cost. Therefore, we investigate other four-vane RFQ designs which can have potential advantages and different mode spectrum. These designs are realized by modifying the RFQ ...Show More
Radio frequency quadrupole cavity structure for particle accelerators — Simulation and measurements
2013 IEEE MTT-S International Microwave Symposium Digest (MTT)
Year: 2013 | Conference Paper |
EM simulation of long RFQ with quadruple ridge (vane) waveguide structure with narrow vane gaps and vane end cutbacks is a complex and challenging task. Advances in 3-D EM simulation tools in recent years can lead to accurate analysis of such structures. Here, we present the simulation of long RFQs (over 2λ), validate our results with measurements, compare simulated results of eigenmode frequencie...Show More
Investigation of Electromagnetic Field Perturbation With Respect to Mechanical Imperfections in Radio-Frequency Quadrupole (RFQ) Structure
Electromagnetic (EM) fields near the beam axis in a radio frequency quadrupole (RFQ) are very sensitive to dimensional changes especially on vane tip geometries. Due to measurement difficulties, field distribution around the beam axis is generally assumed to be equal to that measured outside of vane gaps in quadrants using a bead-pull technique. If an RFQ structure has any mechanical imperfections...Show More
Twisted waveguides for particle accelerator applications
2009 IEEE MTT-S International Microwave Symposium Digest
Year: 2009 | Conference Paper |
Cited by: Papers (1)
A novel microwave device for accelerating charged particles based on twisted waveguide is presented. Twisted guides support slow-wave TM modes whose phase velocity could reach the speed of light c. The axial electric field in these structures can travel synchronously with the particles to achieve nearly uniform acceleration in a traveling-wave topology. The advantages of using twisted guides over ...Show More
Applications of Twisted Hollow Waveguides as Accelerating Structures
A new class of accelerating structures employing a uniformly twisted waveguide is considered. Such a twisted helical structure can be designed to have a specified longitudinal cross section. The design of twisted accelerating structures is discussed with regard to particle velocity and strength of the accelerating field. It is shown how to choose a cross section and twist rate in order to produce ...Show More
The propagation characteristics of twisted hollow waveguides are considered, and various analysis methods are proposed. It is shown that a twisted hollow waveguide can support waves that travel at a speed slower than the speed of light c. These modes are of particular interest, as slow wave structures have many potential applications in accelerators and electron traveling wave tubes. Since there i...Show More
An accurate and stable fourth order finite difference time domain method
Joshua Wilson;Cheng Wang;Songnan Yang;Aly E. Fathy;Yoon W. Kang
2008 IEEE MTT-S International Microwave Symposium Digest
Year: 2008 | Conference Paper |
A long-stencil fourth order finite difference method over a Yee-grid is developed to solve Maxwell’s equations. The different variables are located at staggered mesh points, and a symmetric image formula is introduced near the boundary. The introduction of these symmetric ghost grid points assures the stability of the boundary extrapolation, and in turn a complete set of purely imaginary eigenvalu...Show More
Development of an RF Conditioning System for Charged-Particle Accelerators
Charged-particle accelerators use various vacuum windows on their accelerating radio-frequency (RF) cavities to throughput very high RF power. Before being placed on the cavities, the windows should be cleaned, baked, and fully RF conditioned to prevent a poor vacuum from outgassing, as well as other forms of contamination. An example is the coaxial fundamental power coupler (FPC) with an annular ...Show More
Design and high power processing of RFQ input power couplers
Y. W. Kang;A. Vassioutchenko;A. V. Aleksandrov;D. Anderson;M. S. Champion;M. Crofford;P. Gibson;T. Hardek;P. Ladd;M. P. McCarthy;D. Stout
A RF power coupling system has been developed for future upgrade of input coupling of the RFQ in the SNS linac. The design employs two coaxial loop couplers for 402.5 MHz operation. Each loop is fed through a coaxial ceramic window that is connected to an output of a magic-T waveguide hybrid through a coaxial to waveguide transition. The coaxial loop couplers are designed, manufactured, and high p...Show More
Status of the SNS cryomodule test
S. Kim;I. E. Campisi;F. Casagrande;M. Crofford;Y. Kang;Z. Kursun;D. Stout;A. Vassioutchenko
The cryomodule tests are on going to have better understandings of physics as a whole and eventually to provide safe and reliable operation for neutron production. Some features are revealed to be interesting issues and need more attentions than expected, such as operating condition, collective effects between cavities, HOM coupler issues, end-group stability, cavity-coupler interactions, and vacu...Show More
Development and testing of high power RF vector modulators
Y. W. Kang;J. L. Wilson;M. Champion;T. Hardek;S-H. Kim;M. McCarthy;A. Vassioutchenko
2007 IEEE Particle Accelerator Conference (PAC)
Year: 2007 | Conference Paper |
A fan-out RF power distribution system can allow many accelerating cavities to be powered by a single high-power klystron amplifier. High-power vector modulators can perform independent control of amplitudes and phases of RF voltages at the cavities without changing the klystron signal. A prototype high-power RF vector modulator employing a quadrature hybrid and two ferrite phase shifters in coaxi...Show More
Transient beam-loading detection in an SNS cavity- simulations and initial measurements
Y. Zhang;I. E. Campisi;C. Deibele;J. Galambos;S. D. Henderson;H. Ma;Y. Kang;J. Wilson
2007 IEEE Particle Accelerator Conference (PAC)
Year: 2007 | Conference Paper |
Beam phase measurement based on the detection of a transient beam-loading signal in a SC cavity has the potential to become a very fast linac tune-up technique, especially for an electron linac, as it may precisely set up the cavity's synchronous phase. A large signal-to-noise ratio is critical in the development of a transient detector technique. This paper discusses the study of a transient dete...Show More
Status and performance of the spallation neutron source superconducting linac
I.E. Campisi;S. Assadi;F. Casagrande;M. Crofford;G. Dodson;J. Galambos;M. Giannella;S. Henderson;M. Howell;Y. Kang;K. Kasemir;S.H. Kim;Z. Kursun;P. Ladd;H. Ma;D. Stout;W. Strong;Y. Zhang;M. Champion
The Superconducting Linac at SNS has been operating with beam for almost two years. As the first operational pulsed superconducting linac, many of the aspects of its performance were unknown and unpredictable. A lot of experience has been gathered during the commissioning of its components, during the beam turn on and during operation at increasingly higher beam power. Some cryomodules have been c...Show More
Status and performance of the spallation neutron source superconducting linac
I.E. Campisi;S. Assadi;F. Casagrande;M. Crofford;G. Dodson;J. Galambos;M. Giannella;S. Henderson;M. Howell;Y. Kang;K. Kasemir;S.H. Kim;Z. Kursun;P. Ladd;H. Ma;D. Stout;W. Strong;Y. Zhang;M. Champion
Year: 2007 | Conference Paper |
Status of the spallation neutron source superconducting RF facilities
D. Stout;S. Assadi;I. Campisi;F. Casagrande;M. Crofford;R. Devan;X. Geng;T. Hardek;S. Henderson;M. Howell;Y. Kang;W. Stone;W. Strong;D. Williams;P. Wright
The spallation neutron source (SNS) project was completed with only limited superconducting RF (SRF) facilities installed as part of the project. A concerted effort has been initiated to install the infrastructure and equipment necessary to maintain and repair the superconducting Linac, and to support power upgrade research and development (R&D). Installation of a Class 10/100/10,000 cleanroom and...Show More
Spallation Neutron Source (SNS) high pulse repetition rate considerations
M. McCarthy;D. Anderson;I. Campisi;F. Casagrande;R. Cutler;G. Dodson;K. Kasemir;S. Kim;D. Gurd;J. Galambos;Y. Kang;H. Ma;B. Riemer;J. Schubert;M. Stockli
2007 IEEE Particle Accelerator Conference (PAC)
Year: 2007 | Conference Paper |
Increasing the pulse repetition rate (PRR) of the SNS Linac to its designed maximum of 60 Hz to provide 1.4 MW of beam on target is in progress. Operation above 60 Hz to provide beam to a second target is also being considered in the future. Increasing the PRR to 80 Hz would allow the additional pulses to be diverted to a second target. This paper discusses the impact of increasing the PRR on the ...Show More
Advanced RF-driven H- ion sources at the SNS
R.F. Welton;M. P. Stockli;S.N. Murray;T. R. Pennisi;B. Han;Y. Kang;R.H. Goulding;D.W. Crisp;N.P. Luciano;J. R. Carmichael;J. Carr
2007 IEEE Particle Accelerator Conference (PAC)
Year: 2007 | Conference Paper |
Cited by: Patents (5)
The US spallation neutron source* (SNS), will require substantially higher average and pulse H" beam current than can be produced from conventional H- ion sources such as the baseline LBNL-SNS source. H- currents of 70-100 mA with an RMS emittance of 0.20-0.35 π mm mrad and a ˜7% duty-factor will be needed for the SNS power upgrade project in 2010. We are therefore investigating several advanced i...Show More
Development of Fast High-Power Rf Vector Modulator Employing Tem Ferrite Phase Shifters
Yoon Kang;Joshua Wilson;Thomas Hardek;Alexander Vassioutchenko
2007 IEEE/MTT-S International Microwave Symposium
Year: 2007 | Conference Paper |
Recent charged-particle accelerator projects employ high power RF distribution systems to power superconducting radio frequency (SRF) accelerating cavities. Each cavity usually requires several hundred killowatts of pulsed power at relatively high duty cycle (roughly up to 10% in high-power proton linear accelerators) in low UHF bands for production of the particle beam. So far, one amplifier to o...Show More
Spallation Neutron Source High Power RF Installation and Commissioning Progress
M. McCarthy;D. Anderson;R. Fuja;P. Gurd;T. Hardek;Y. Kang;J. Bradley;K. Young;D. Rees;W. Roybal
Proceedings of the 2005 Particle Accelerator Conference
Year: 2005 | Conference Paper |
Cited by: Papers (1)
The Spallation Neutron Source (SNS) linac will provide a 1 GeV proton beam for injection into the accumulator ring. In the normal conducting (NC) section of this linac, the Radio Frequency Quadupole (RFQ) and six drift tube linac (DTL) tanks are powered by seven 2.5 MW, 402.5 MHz klystrons and the four coupled cavity linac (CCL) cavities are powered by four 5.0 MW, 805 MHz klystrons. Eighty-one 55...Show More
High Power RF Test Facility at the SNS
Y. Kang;D. Anderson;I.E. Campisi;M.S. Champion;M. Crofford;R. Fuja;P. Gurd;S.M.S. Hasan;K. Kasemir;M. McCarthy;D. Stout;J. Tang;A. Vassioutchenko;M. Wezensky;G.K. Davis;M. Drury;T. Powers;M. Stirbet
Proceedings of the 2005 Particle Accelerator Conference
Year: 2005 | Conference Paper |
Cited by: Papers (3)
RF Test Facility (RFTF) has been constructed to support present and future needs in testing, processing and conditioning of various high power RF components of normal conducting and superconducting systems at the SNS. The facility is expected to have additional subsystems that are needed for complete superconducting RF (SRF) testing and processing. A full capacity high voltage converter modulator ...Show More
Installation and Testing for Commissioning of Normal Conducting RF Linac Segment in the SNS
Y. Kang;A. Aleksandrov;D. Anderson;M.M. Champion;M.S. Champion;M. Crofford;C. Deibele;G. Dodson;R. Fuja;P. Gibson;P. Gurd;T. Hardek;G. Johnson;P. Ladd;H. Ma;M. McCarthy;M. Piller;J. Tang;A. Vassioutchenko;D. Williams;J. Billen;J. Bradley;D. Rees;W. Roybal;J. Stovall;K. Young;L. Young
Proceedings of the 2005 Particle Accelerator Conference
Year: 2005 | Conference Paper |
Cited by: Papers (1)
The Spallation Neutron Source (SNS) linac will deliver a 1.0 GeV proton beam to its accumulator ring. The normal conducting segment of the linac has a radio frequency quadrupole (RFQ), six drift tube linac (DTL) tanks powered by seven 402.5 MHz klystrons and four coupled cavity linac (CCL) modules powered by four 805 MHz klystrons that deliver the 180 MeV beam to the superconducting section of the...Show More
Installation and Testing for Commissioning of Normal Conducting RF Linac Segment in the SNS
Y. Kang;A. Aleksandrov;D. Anderson;M.M. Champion;M.S. Champion;M. Crofford;C. Deibele;G. Dodson;R. Fuja;P. Gibson;P. Gurd;T. Hardek;G. Johnson;P. Ladd;H. Ma;M. McCarthy;M. Piller;J. Tang;A. Vassioutchenko;D. Williams;J. Billen;J. Bradley;D. Rees;W. Roybal;J. Stovall;K. Young;L. Young
Year: 2005 | Conference Paper |
RF Conditioning and Testing of Fundamental Power Couplers for SNS Superconducting Cavity Production
M. Stirbet;K.M. Wilson;M. Wiseman;J. Henry;M. Drury;G.K. Davis;C. Grenoble;T. Powers;G. Myneni;I.E. Campisi;Y. Kang;D. Stout
Proceedings of the 2005 Particle Accelerator Conference
Year: 2005 | Conference Paper |
The Spallation Neutron Source (SNS) makes use of 33 medium beta (0.61) and 48 high beta (0.81) superconducting cavities. Each cavity is equipped with a fundamental power coupler, which should withstand the full klystron power of 550 kW in full reflection for the duration of an RF pulse of 1.3 msec at 60 Hz repetition rate. Before assembly to a superconducting cavity, the vacuum components of the c...Show More
4.2 K Operation of the SNS Cryomodules
I.E. Campisi;S. Assadi;F. Casagrande;M. Champion;P. Chu;S. Cousineau;M. Crofford;C. Deibele;J.D. Galambos;P. Gurd;D. Hatfield;M. Howell;D. Jeon;Y.W. Kang;K. Kasemir;Z. Kursun;H. Ma;M. Piller;D. Stout;W. Strong;A. Vassioutchenko;Y. Zhang
Proceedings of the 2005 Particle Accelerator Conference
Year: 2005 | Conference Paper |
Cited by: Papers (2)
The Spallation Neutron Source being built at Oak Ridge National Laboratory employs eighty one 805 MHz superconducting cavities operated at 2.1 K to accelerate the H-beam from 187 MeV to about 1 GeV. The superconducting cavities and cryomodules with two different values of beta (. 61 and .81) have been designed and constructed at Jefferson Lab for operation at 2.1 K with unloaded Q’s in excess of 5...Show More
4.2 K Operation of the SNS Cryomodules
I.E. Campisi;S. Assadi;F. Casagrande;M. Champion;P. Chu;S. Cousineau;M. Crofford;C. Deibele;J.D. Galambos;P. Gurd;D. Hatfield;M. Howell;D. Jeon;Y.W. Kang;K. Kasemir;Z. Kursun;H. Ma;M. Piller;D. Stout;W. Strong;A. Vassioutchenko;Y. Zhang
Year: 2005 | Conference Paper |
Electromagnetic simulations and properties of the fundamental power couplers for the SNS superconducting cavities
Y. Kang;S. Kim;M. Doleans;I.E. Campisi;M. Stirbet;P. Kneisel;G. Ciovati;G. Wu;P. Yla-Oijala
PACS2001. Proceedings of the 2001 Particle Accelerator Conference (Cat. No.01CH37268)
Year: 2001 | Conference Paper |
Cited by: Papers (10)
The Spallation Neutron Source (SNS) makes use of superconducting cavities for the acceleration of negative H ions in the main linac. Two types of 6-cell Niobium cavities are used in the superconducting portion of the linac: 33 /spl beta/=0.61 cavities and 48 /spl beta/=0.81 cavities. Each cavity is powered via a coaxial fundamental power coupler (FPC) of a simple yet robust design. The electromagn...Show More
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