RF Coupler Design for the TRIUMF ISAC-II Superconducting Quarter Wave Resonator
Poirier, R L; Harmer, P; Laxdal, R E; Mitra, A K; Sekatchev, I; Waraich, B; Zvyagintsev, V
2004-01-01
An RF Coupler for the ISAC-II medium beta (β=0.058 and 0.071) superconducting quarter wave resonators was designed and tested at TRIUMF. The main goal of this development was to achieve stable operation of superconducting cavities at high acceleration gradients and low thermal load to the helium refrigeration system. The cavities will operate at 6 MV/m acceleration gradient in overcoupled mode at a forward power 200 W at 106 MHz. The overcoupling provides ±20 Hz cavity bandwidth, which improves the stability of the RF control system for fast helium pressure fluctuations, microphonics and environmental noise. Choice of materials, cooling with liquid nitrogen, aluminum nitride RF window and thermal shields insure a small thermal load on the helium refrigeration system by the Coupler. An RF finger contact which causedμdust in the coupler housing was eliminated without any degradation of the coupler performance. RF and thermal calculations, design and test results on the coupler are p...
rf coupler technology for fusion applications
International Nuclear Information System (INIS)
Hoffman, D.J.
1983-01-01
Radio frequency (rf) oscillations at critical frequencies have successfully provided a means to convey power to fusion plasmas due to the electrical-magnetic properties of the plasma. While large rf systems to couple power to the plasma have been designed, built, and tested, the main link to the plasma, the coupler, is still in an evolutionary stage of development. Design and fabrication of optimal antennas for fusion applications are complicated by incomplete characterizations of the harsh plasma environment and of coupling mechanisms. A brief description of rf coupler technology required for plasma conditions is presented along with an assessment of the status and goals of coupler development
RF characterization and testing of ridge waveguide transitions for RF power couplers
Energy Technology Data Exchange (ETDEWEB)
Kumar, Rajesh; Jose, Mentes; Singh, G.N. [Ion Accelerator Development Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kumar, Girish [Department of Electrical Engineering, IIT Bombay, Mumbai 400076,India (India); Bhagwat, P.V. [Ion Accelerator Development Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)
2016-12-01
RF characterization of rectangular to ridge waveguide transitions for RF power couplers has been carried out by connecting them back to back. Rectangular waveguide to N type adapters are first calibrated by TRL method and then used for RF measurements. Detailed information is obtained about their RF behavior by measurements and full wave simulations. It is shown that the two transitions can be characterized and tuned for required return loss at design frequency of 352.2 MHz. This opens the possibility of testing and conditioning two transitions together on a test bench. Finally, a RF coupler based on these transitions is coupled to an accelerator cavity. The power coupler is successfully tested up to 200 kW, 352.2 MHz with 0.2% duty cycle.
rf coaxial couplers for high-intensity linear accelerators
International Nuclear Information System (INIS)
Manca, J.J.; Knapp, E.A.
1980-02-01
Two rf coaxial couplers that are particularly suitable for intertank connection of the disk-and-washer accelerating structure for use in high-intensity linear accelerators have been developed. These devices have very high coupling to the accelerating structure and very low rf power loss at the operating frequency, and they can be designed for any relative particle velocity β > 0.4. Focusing and monitoring devices can be located inside these couplers
RF Processing of the Couplers for the SNS Superconducting Cavities
International Nuclear Information System (INIS)
Y.Kang; I.E. Campisi; D. Stout; A. Vassioutchenko; M. Stirbet; M. Drury; T. Powers
2005-01-01
All eighty-one fundamental power couplers for the 805 MHz superconducting cavities of the SNS linac have been RF conditioned and installed in the cryomodules successfully. The couplers were RF processed at JLAB or at the SNS in ORNL: more than forty couplers have been RF conditioned in the SNS RF Test Facility (RFTF) after the first forty couplers were conditioned at JLAB. The couplers were conditioned up to 650 kW forward power at 8% duty cycle in traveling and standing waves. They were installed on the cavities in the cryomodules and then assembled with the airside waveguide transitions. The couplers have been high power RF tested with satisfactory accelerating field gradients in the cooled cavities
HOM Coupler Optimisation for the Superconducting RF Cavities in ESS
Ainsworth, R; Calaga, R
2012-01-01
The European Spallation Source (ESS) will be the world’s most powerful next generation neutron source. It consists of a linear accelerator, target, and instruments for neutron experiments. The linac is designed to accelerate protons to a final energy of 2.5 GeV, with an average design beam power of 5 MW, for collision with a target used to produce a high neutron flux. A section of the linac will contain Superconducting RF (SCRF) cavities designed at 704 MHz. Beam induced HOMs in these cavities may drive the beam unstable and increase the cryogenic load, therefore HOM couplers are installed to provide sufficient damping. Previous studies have shown that these couplers are susceptible to multipacting, a resonant process which can absorb RF power and lead to heating effects. This paper will show how a coupler suffering from multipacting has been redesigned to limit this effect. Optimisation of the RF damping is also discussed.
Cancellation of RF Coupler-Induced Emittance Due to Astigmatism
Energy Technology Data Exchange (ETDEWEB)
Dowell, David H.; /SLAC
2016-12-11
It is well-known that the electron beam quality required for applications such as FEL’s and ultra-fast electron diffraction can be degraded by the asymmetric fields introduced by the RF couplers of superconducting linacs. This effect is especially troublesome in the injector where the low energy beam from the gun is captured into the first high gradient accelerator section. Unfortunately modifying the established cavity design is expensive and time consuming, especially considering that only one or two sections are needed for an injector. Instead, it is important to analyze the coupler fields to understand their characteristics and help find less costly solutions for their cancellation and mitigation. This paper finds the RF coupler-induced emittance for short bunches is mostly due to the transverse spatial sloping or tilt of the field, rather than the field’s time-dependence. It is shown that the distorting effects of the coupler can be canceled with a static (DC) quadrupole lens rotated about the z-axis.
Study of a power coupler for superconducting RF cavities used in high intensity proton accelerator
International Nuclear Information System (INIS)
Souli, M.
2007-07-01
The coaxial power coupler needed for superconducting RF cavities used in the high energy section of the EUROTRANS driver should transmit 150 kW (CW operation) RF power to the protons beam. The calculated RF and dielectric losses in the power coupler (inner and outer conductor, RF window) are relatively high. Consequently, it is necessary to design very carefully the cooling circuits in order to remove the generated heat and to ensure stable and reliable operating conditions for the coupler cavity system. After calculating all type of losses in the power coupler, we have designed and validated the inner conductor cooling circuit using numerical simulations results. We have also designed and optimized the outer conductor cooling circuit by establishing its hydraulic and thermal characteristics. Next, an experiment dedicated to study the thermal interaction between the power coupler and the cavity was successfully performed at CRYOHLAB test facility. The critical heat load Qc for which a strong degradation of the cavity RF performance was measured leading to Q c in the range 3 W-5 W. The measured heat load will be considered as an upper limit of the residual heat flux at the outer conductor cold extremity. A dedicated test facility was developed and successfully operated for measuring the performance of the outer conductor heat exchanger using supercritical helium as coolant. The test cell used reproduces the realistic thermal boundary conditions of the power coupler mounted on the cavity in the cryo-module. The first experimental results have confirmed the excellent performance of the tested heat exchanger. The maximum residual heat flux measured was 60 mW for a 127 W thermal load. As the RF losses in the coupler are proportional to the incident RF power, we can deduce that the outer conductor heat exchanger performance is continued up to 800 kW RF power. Heat exchanger thermal conductance has been identified using a 2D axisymmetric thermal model by comparing
Design of a 300 GHz Broadband TWT Coupler and RF-Structure
Krawczyk, F L
2004-01-01
Recent LANL activities in millimeter wave structures focus on 94 and 300 GHz structures. They aim at power generation from low power (1002000 W) with a round electron beam (120 kV, 0.11.0 A) to high power (2100 kW) with a sheet beam structure (120 kV, 20 A). Applications cover basic research, radar and secure communications and remote sensing of biological and chemical agents. In this presentation the design and cold-test measurements of a 300 GHz RF-structure with a broadband (>6% bandwidth) power coupler are presented. The design choice of two input/output waveguides, a special coupling region and the structure parameters themselves are presented. As a benchmark also a scaled up version at 10 GHz was designed and measured. These results will also be presented.
Suppression of multipacting in high power RF couplers operating with superconducting cavities
Energy Technology Data Exchange (ETDEWEB)
Ostroumov, P.N., E-mail: ostroumov@frib.msu.edu [Facility for Rare Isotope Beams (FRIB), Michigan State University, East Lansing, MI 48824 (United States); Kazakov, S. [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Morris, D.; Larter, T.; Plastun, A.S.; Popielarski, J.; Wei, J.; Xu, T. [Facility for Rare Isotope Beams (FRIB), Michigan State University, East Lansing, MI 48824 (United States)
2017-06-01
Capacitive input couplers based on a 50 Ω coaxial transmission line are frequently used to transmit RF power to superconducting (SC) resonators operating in CW mode. It is well known that coaxial transmission lines are prone to multipacting phenomenon in a wide range of RF power level and operating frequency. The Facility for Rare Isotope Beams (FRIB) being constructed at Michigan State University includes two types of quarter wave SC resonators (QWR) operating at 80.5 MHz and two types of half wave SC resonators (HWR) operating at 322 MHz. As was reported in ref. [1] a capacitive input coupler used with HWRs was experiencing strong multipacting that resulted in a long conditioning time prior the cavity testing at design levels of accelerating fields. We have developed an insert into 50 Ω coaxial transmission line that provides opportunity to bias the RF coupler antenna and protect the amplifier from the bias potential in the case of breakdown in DC isolation. Two of such devices have been built and are currently used for the off-line testing of 8 HWRs installed in the cryomodule.
Time-Domain Simulation of RF Couplers
International Nuclear Information System (INIS)
Smithe, David; Carlsson, Johan; Austin, Travis
2009-01-01
We have developed a finite-difference time-domain (FDTD) fluid-like approach to integrated plasma-and-coupler simulation [1], and show how it can be used to model LH and ICRF couplers in the MST and larger tokamaks.[2] This approach permits very accurate 3-D representation of coupler geometry, and easily includes non-axi-symmetry in vessel wall, magnetic equilibrium, and plasma density. The plasma is integrated with the FDTD Maxwell solver in an implicit solve that steps over electron time-scales, and permits tenuous plasma in the coupler itself, without any need to distinguish or interface between different regions of vacuum and/or plasma. The FDTD algorithm is also generalized to incorporate a time-domain sheath potential [3] on metal structures within the simulation, to look for situations where the sheath potential might generate local sputtering opportunities. Benchmarking of the time-domain sheath algorithm has been reported in the references. Finally, the time-domain software [4] permits the use of particles, either as field diagnostic (test particles) or to self-consistently compute plasma current from the applied RF power.
High-power RF window and coupler development for the PEP-II B Factory
International Nuclear Information System (INIS)
Neubauer, M.; Fant, K.; Hodgson, J.; Judkins, J.; Schwarz, H.; Rimmer, R.A.
1995-05-01
We describe the fabrication and testing of the RF windows designed to transmit power to the PEP-II 476 MHz cavities. Design choices to maximize the reliability of the window are discussed. Fabrication technologies for the window are described and finite-element analysis of the assembly process is presented. Conditioning and high-power testing of the window are discussed. Design of the coupler assembly including the integration of the window and other components is reported
A calculation method for RF couplers design based on numerical simulation by microwave studio
International Nuclear Information System (INIS)
Wang Rong; Pei Yuanji; Jin Kai
2006-01-01
A numerical simulation method for coupler design is proposed. It is based on the matching procedure for the 2π/3 structure given by Dr. R.L. Kyhl. Microwave Studio EigenMode Solver is used for such numerical simulation. the simulation for a coupler has been finished with this method and the simulation data are compared with experimental measurements. The results show that this numerical simulation method is feasible for coupler design. (authors)
Design of a 300 GHZ broadband coupler and RF-structure
International Nuclear Information System (INIS)
Krawczyk, F.L.; Carlsten, B.E.; Earley, L.M.; Sigler, F.E.; Potter, J.M.; Schulze, M.E.
2004-01-01
Recent LANL activities in millimeter wave structures focus on 95 and 300 GHz structures. They aim at power generation from low power (100W-2kW) with a round electron beam (120kV, 0.1-1.0 A) to high power (2-100 kW) with a sheet beam structure (120 kV, 20 A). Applications cover basic research, radar and secure communications and remote sensing of biological and chemical agents. In this presentation the design of a 300 GHz RF-structure with a broadband (> 6% bandwidth) power coupler is presented. The choice of two input/output waveguides, a special coupling region and the structure parameters are presented. As a benchmark also a scaled up version at 10 GHz was designed and measured. These results will also be presented. We are investigating planar micro-fabricated traveling-wave tube amplifiers as sources for the generation of millimeter waves from 95 to 300 GHz. While for low energy applications narrow structures with pencil beams are proposed, for high energy operation flat, thin sheet beams are required. For the latter vane-loaded rectangular waveguides that operate in a slow-wave mode matched to the velocity of the electron beam are especially well suited. The 300 GHz effort initially is limited to narrow structures for pencil beams. The main emphasis for this work are the study of fabrication issues and the understanding of features that allow a broadband operation (5-10% bandwidth).
Coupler induced monopole component and its minimization in deflecting cavities
Directory of Open Access Journals (Sweden)
P. K. Ambattu
2013-06-01
Full Text Available Deflecting cavities are used in particle accelerators for the manipulation of charged particles by deflecting or crabbing (rotating them. For short deflectors, the effect of the power coupler on the deflecting field can become significant. The particular power coupler type can introduce multipole rf field components and coupler-specific wakefields. Coupler types that would normally be considered like standard on-cell coupler, waveguide coupler, or mode-launcher coupler could have one or two rf feeds. The major advantage of a dual-feed coupler is the absence of monopole and quadrupole rf field components in the deflecting structure. However, a dual-feed coupler is mechanically more complex than a typical single-feed coupler and needs a splitter. For most applications, deflecting structures are placed in regions where there is small space hence reducing the size of the structure is very desirable. This paper investigates the multipole field components of the deflecting mode in single-feed couplers and ways to overcome the effect of the monopole component on the beam. Significant advances in performance have been demonstrated. Additionally, a novel coupler design is introduced which has no monopole field component to the deflecting mode and is more compact than the conventional dual-feed coupler.
Numerical design of an rf-coupling Iris
International Nuclear Information System (INIS)
Hanaki, H.
1991-07-01
For an rf coupler of an rf system in high-quality transmission an analytical method may be applied to treat the design problem, if a coupling hole between cavities or waveguides is small enough. However, in most cases of accelerator engineering the dimensions of the coupling slots are not so small compared with the size of a cavity and a waveguide. Numerical design of rf coupling slots for a few cases is tried basically according to Henke's method using an equivalent circuit to treat the matching of microwave components, but taking account of beam loading expressed by the coupling coefficient β. The MAFIA code has been applied for the design. (R.P.) 5 refs., 10 figs., 3 tabs
Development of fundamental power coupler for C-ADS superconducting elliptical cavities
Gu, Kui-Xiang; Bing, Feng; Pan, Wei-Min; Huang, Tong-Ming; Ma, Qiang; Meng, Fan-Bo
2017-06-01
5-cell elliptical cavities have been selected for the main linac of the China Accelerator Driven sub-critical System (C-ADS) in the medium energy section. According to the design, each cavity should be driven with radio frequency (RF) energy up to 150 kW by a fundamental power coupler (FPC). As the cavities work with high quality factor and high accelerating gradient, the coupler should keep the cavity from contamination in the assembly procedure. To fulfil the requirements, a single-window coaxial type coupler was designed with the capabilities of handling high RF power, class 10 clean room assembly, and heat load control. This paper presents the coupler design and gives details of RF design, heat load optimization and thermal analysis as well as multipacting simulations. In addition, a primary high power test has been performed and is described in this paper. Supported by China ADS Project (XDA03020000) and National Natural Science Foundation of China (11475203)
Conceptual design of a sapphire loaded coupler for superconducting radio-frequency 1.3 GHz cavities
Xu, Chen; Tantawi, Sami
2016-02-01
This paper explores a hybrid mode rf structure that served as a superconducting radio-frequency coupler. This application achieves a reflection S(1 ,1 ) varying from 0 to -30 db and delivers cw power at 7 KW. The coupler has good thermal isolation between the 2 and 300 K sections due to vacuum separation. Only one single hybrid mode can propagate through each section, and no higher order mode is coupled. The analytical and numerical analysis for this coupler is given and the design is optimized. The coupling mechanism to the cavity is also discussed.
Design Topics for Superconducting RF Cavities and Ancillaries
International Nuclear Information System (INIS)
Padamsee, H
2014-01-01
RF superconductivity has become a major subfield of accelerator science. There has been an explosion in the number of accelerator applications and in the number of laboratories engaged. The first lecture at this meeting of the CAS presented a review of fundamental design principles to develop cavity geometries to accelerate velocity-of-light particles (β = v/c ~ 1), moving on to the corresponding design principles for medium-velocity (medium-β) and low-velocity (low-β) structures. The lecture included mechanical design topics. The second lecture dealt with input couplers, higher-order mode extraction couplers with absorbers, and tuners of both the slow and fast varieties
Design Topics for Superconducting RF Cavities and Ancillaries
Energy Technology Data Exchange (ETDEWEB)
Padamsee, H [Cornell University, CLASSE (United States)
2014-07-01
RF superconductivity has become a major subfield of accelerator science. There has been an explosion in the number of accelerator applications and in the number of laboratories engaged. The first lecture at this meeting of the CAS presented a review of fundamental design principles to develop cavity geometries to accelerate velocity-of-light particles (β = v/c ~ 1), moving on to the corresponding design principles for medium-velocity (medium-β) and low-velocity (low-β) structures. The lecture included mechanical design topics. The second lecture dealt with input couplers, higher-order mode extraction couplers with absorbers, and tuners of both the slow and fast varieties.
International Nuclear Information System (INIS)
Cavallari, G.; Chiaveri, E.; Haebel, E.; Legendre, P.; Weingarten, W.
1988-01-01
This paper discusses the coupler developments that have taken place at CERN since the last RF superconductivity workshop. At that time beam tube coupling was just starting to be examined. It was found that in restricting the number of cells to four with the correct amount of intercell coupling, and endcells compensated simultaneously for several modes, trapped modes can be avoided at least up to three and a half times the fundamental mode frequency. This result is regarded as a sufficiently safe basis to switch over to beam tube coupling with two higher order mode (hom) couplers, one on each side and with 65 degrees in between them, and in addition one beam tube power coupler. The characteristics of the cavity and the machine determine the basic coupler specifications. Four designs are discussed for hom couplers. 22 reference, 15 figures, 2 tables
Wakefield and RF Kicks Due to Coupler Asymmetry in TESLA-Type Accelerating Cavities
International Nuclear Information System (INIS)
Bane, K
2008-01-01
In a future linear collider, such as the International Linear Collider (ILC), trains of high current, low emittance bunches will be accelerated in a linac before colliding at the interaction point. Asymmetries in the accelerating cavities of the linac will generate fields that will kick the beam transversely and degrade the beam emittance and thus the collider performance. In the main linac of the ILC, which is filled with TESLA-type superconducting cavities, it is the fundamental (FM) and higher mode (HM) couplers that are asymmetric and thus the source of such kicks. The kicks are of two types: one, due to (the asymmetry in) the fundamental RF fields and the other, due to transverse wakefields that are generated by the beam even when it is on axis. In this report we calculate the strength of these kicks and estimate their effect on the ILC beam. The TESLA cavity comprises nine cells, one HM coupler in the upstream end, and one (identical, though rotated) HM coupler and one FM coupler in the downstream end (for their shapes and location see Figs. 1, 2) [1]. The cavity is 1.1 m long, the iris radius 35 mm, and the coupler beam pipe radius 39 mm. Note that the couplers reach closer to the axis than the irises, down to a distance of 30 mm
Conceptual design of a sapphire loaded coupler for superconducting radio-frequency 1.3 GHz cavities
Directory of Open Access Journals (Sweden)
Chen Xu
2016-02-01
Full Text Available This paper explores a hybrid mode rf structure that served as a superconducting radio-frequency coupler. This application achieves a reflection S_{(1,1} varying from 0 to −30 db and delivers cw power at 7 KW. The coupler has good thermal isolation between the 2 and 300 K sections due to vacuum separation. Only one single hybrid mode can propagate through each section, and no higher order mode is coupled. The analytical and numerical analysis for this coupler is given and the design is optimized. The coupling mechanism to the cavity is also discussed.
International Nuclear Information System (INIS)
K. M. Wilson; I. E. Campisi; E. F. Daly; G. K. Davis; M. Drury; J. E. Henry; P. Kneisel; G. Myneni; T. Powers; W. J. Schneider; M. Stirbet; Y. Kang; K. Cummings; T. Hardek
2001-01-01
Each of the 805 MHz superconducting cavities of the Spallation Neutron Source (SNS) is powered via a coaxial Fundamental Power Coupler (FPC) with a 50 Omega impedance and a warm planar alumina window. The design is derived from the experience of other laboratories; in particular, a number of details are based on the coupler developed for the KEK B-Factory superconducting cavities. However, other design features have been modified to account for the fact that the SNS FPC will transfer a considerably lower average power than the KEK-B coupler. Four prototypes have been manufactured so far, and preliminary tests performed on two of them at Los Alamos National Laboratory (LANL). During these tests, peak powers of over 500 kW were transferred through the couplers in the test stand designed and built for this purpose. This paper gives details of the coupler design and of the results obtained from the RF tests on the test stand during the last few months. A more comprehensive set of tests is planned for the near future
Energy Technology Data Exchange (ETDEWEB)
Souli, M
2007-07-15
The coaxial power coupler needed for superconducting RF cavities used in the high energy section of the EUROTRANS driver should transmit 150 kW (CW operation) RF power to the protons beam. The calculated RF and dielectric losses in the power coupler (inner and outer conductor, RF window) are relatively high. Consequently, it is necessary to design very carefully the cooling circuits in order to remove the generated heat and to ensure stable and reliable operating conditions for the coupler cavity system. After calculating all type of losses in the power coupler, we have designed and validated the inner conductor cooling circuit using numerical simulations results. We have also designed and optimized the outer conductor cooling circuit by establishing its hydraulic and thermal characteristics. Next, an experiment dedicated to study the thermal interaction between the power coupler and the cavity was successfully performed at CRYOHLAB test facility. The critical heat load Qc for which a strong degradation of the cavity RF performance was measured leading to Q{sub c} in the range 3 W-5 W. The measured heat load will be considered as an upper limit of the residual heat flux at the outer conductor cold extremity. A dedicated test facility was developed and successfully operated for measuring the performance of the outer conductor heat exchanger using supercritical helium as coolant. The test cell used reproduces the realistic thermal boundary conditions of the power coupler mounted on the cavity in the cryo-module. The first experimental results have confirmed the excellent performance of the tested heat exchanger. The maximum residual heat flux measured was 60 mW for a 127 W thermal load. As the RF losses in the coupler are proportional to the incident RF power, we can deduce that the outer conductor heat exchanger performance is continued up to 800 kW RF power. Heat exchanger thermal conductance has been identified using a 2D axisymmetric thermal model by comparing
Development of the SCRF Power Coupler for the APT Accelerator
Energy Technology Data Exchange (ETDEWEB)
Schmierer, E.N.; Lujan, R.E.; Rusnak, B.; Smith, B.; Haynes, W.B.; Gautier, C.; Waynert, J.A.; Krawczyk, F.; Gioia, J.
1999-03-01
The team responsible for the design of the Accelerator Production of Tritium (APT) superconducting (SC) radio frequency (RF) power coupler has developed two 700-MHz, helium gas-cooled power couplers. One has a fixed inner conductor and the other has an adjustable inner conductor (gamma prototype and alpha prototype). The power couplers will be performance tested in the near future. This paper discusses the mechanical design and fabrication techniques employed in the development of each power coupler. This includes material selection, copper coating, assembly sequences, and metal joining procedures, as well as the engineering analyses performed to determine the dynamic response of the inner conductors due to environmental excitations. A bellows is used in both prototype inner conductors in the area near the ceramic RF window, to compensate for thermal expansion and mechanical tolerance build-up. In addition, a bellows is used near the tip of the inner conductor of the alpha prototype for running the power coupler after it is installed on the accelerator. Extensive analytical work has been performed to determine the static loads transmitted by the bellows due to thermally induced expansion on the inner conductor and on the RF window. This paper also discusses this analysis, as well as the mechanical analysis performed to determine the final geometric shape of the bellows. Finally, a discussion of the electromagnetic analysis used to optimize the performance of the power couplers is included.
Asymmetric focusing study from twin input power couplers using realistic rf cavity field maps
Directory of Open Access Journals (Sweden)
Colwyn Gulliford
2011-03-01
Full Text Available Advanced simulation codes now exist that can self-consistently solve Maxwell’s equations for the combined system of an rf cavity and a beam bunch. While these simulations are important for a complete understanding of the beam dynamics in rf cavities, they require significant time and computing power. These techniques are therefore not readily included in real time simulations useful to the beam physicist during beam operations. Thus, there exists a need for a simplified algorithm which simulates realistic cavity fields significantly faster than self-consistent codes, while still incorporating enough of the necessary physics to ensure accurate beam dynamics computation. To this end, we establish a procedure for producing realistic field maps using lossless cavity eigenmode field solvers. This algorithm incorporates all relevant cavity design and operating parameters, including beam loading from a nonrelativistic beam. The algorithm is then used to investigate the asymmetric quadrupolelike focusing produced by the input couplers of the Cornell ERL injector cavity for a variety of beam and operating parameters.
Design and RF Test of Broadband Coaxial Hybrid Splitter for ITER ICRF System
Energy Technology Data Exchange (ETDEWEB)
Kim, H. J.; Wang, S. J.; Park, B. H.; Yang, H. L.; Kwak, J. G. [National Fusion Research Institute, Daejeon (Korea, Republic of); Choi, J. J. [Kwangwoon Univ., Seoul (Korea, Republic of)
2013-10-15
The ICRF system of the ITER is required to couple 20 MW to the plasma in the 40∼55 MHz frequency band for RF heating and current drive operation. The corresponding matching system of ICRF antenna must be load-resilient for a wide range of antenna load variations due to mode transitions or edge localized modes. Indeed the use of hybrid splitters ensures that no reflections occur at the generator when the reflections on the adjacent lines are equal both in magnitude and in phase, in which case all reflected power will not be seen by the generators and will be returned to the dummy loads. Most 3 dB coaxial hybrid circuits installed and implemented on the ICRF system is single section coupler providing best performance at the design frequency with narrow bandwidth. The bandwidth of such a single-section 3 dB hybrid coupler is limited to less than 20% due to the quarter wavelength transmission line requirement. The amplitude balance becomes rapidly degraded away from the center frequency. We designed, fabricated and tested a high power, ultra-wideband two-section 3 dB coaxial hybrid coupler over all frequencies from 40 MHz to 55 MHz for ITER ICRF system by configuring asymmetric impedance matching. We have designed, fabricated, and tested a 3-dB wideband hybrid coupler for stable and load resilient operation of the ITER ICRF system. The wideband two section 3-dB coaxial hybrid coupler was well designed by configuring asymmetric impedance matching using HFSS. In the rf measurements, we found that wideband hybrid splitter has an amplitude imbalance of 0.1 dB over all frequencies from 40 MHz to 55 MHz. We expect that wideband hybrid splitter will be applicable to ITER ICRF matching system for load resilient operation at fusion plasmas.
Design of RF system for CYCIAE-230 superconducting cyclotron
Energy Technology Data Exchange (ETDEWEB)
Yin, Zhiguo, E-mail: bitbearAT@hotmail.com; Ji, Bin; Fu, Xiaoliang; Cao, Xuelong; Zhao, Zhenlu; Zhang, Tinajue
2017-05-11
The CYCIAE230 is a low-current, compact superconducting cyclotron designed for proton therapy. The Radio Frequency system consists of four RF cavities and applies second harmonic to accelerate beams. The driving power for the cavity system is estimated to be approximately 150 kW. The LLRF controller is a self-made device developed and tested at low power using a small-scale cavity model. In this paper, the resonator systems of an S.C. cyclotron in history are reviewed. Contrary to those RF systems, the cavities of the CYCIAE230 cyclotron connect two opposite dees. Two high-power RF windows are included in the system. Each window carries approximately 75 kW RF power from the driver to the cavities. Thus, the RF system for the CY-CIAE230 cyclotron is operated in driven push–pull mode. The two-way amplifier-coupler-cavity systems are operated with approximately the same amount of RF power but 180° out of phase compared with each other. The design, as well as the technical advantage and limitations of this operating mode, of the CYCIAE230 cyclotron RF system is analyzed.
Design of RF system for CYCIAE-230 superconducting cyclotron
Yin, Zhiguo; Ji, Bin; Fu, Xiaoliang; Cao, Xuelong; Zhao, Zhenlu; Zhang, Tinajue
2017-05-01
The CYCIAE230 is a low-current, compact superconducting cyclotron designed for proton therapy. The Radio Frequency system consists of four RF cavities and applies second harmonic to accelerate beams. The driving power for the cavity system is estimated to be approximately 150 kW. The LLRF controller is a self-made device developed and tested at low power using a small-scale cavity model. In this paper, the resonator systems of an S.C. cyclotron in history are reviewed. Contrary to those RF systems, the cavities of the CYCIAE230 cyclotron connect two opposite dees. Two high-power RF windows are included in the system. Each window carries approximately 75 kW RF power from the driver to the cavities. Thus, the RF system for the CY-CIAE230 cyclotron is operated in driven push-pull mode. The two-way amplifier-coupler-cavity systems are operated with approximately the same amount of RF power but 180° out of phase compared with each other. The design, as well as the technical advantage and limitations of this operating mode, of the CYCIAE230 cyclotron RF system is analyzed.
International Nuclear Information System (INIS)
Ghasemi, F.; Abbasi Davani, F.; Lamehi Rachti, M.; Shaker, H.; Ahmadiannamin, S.
2015-01-01
Design and construction of an electron linear accelerator by Institute for Research in Fundamental Science (IPM) is considered as Iran’s first attempt to construct such an accelerator. In order to design a linear accelerating tube, after defining the accelerating tube and buncher geometries, RF input and output couplers must be designed. In this article, firstly, a brief report on the specifications of an S-band electron linear accelerator which is in progress in the school of particles and accelerators is presented and then, the design process and construction reports of the couplers required for this accelerator are described. Through performing necessary calculations and tuning the coupling factor and resonant frequency, couplers with desired specification have been fabricated by shrinking method. The final obtained coupling factor and resonant frequency have been respectively 1.05 and 2997 MHz for the first coupler, and 0.98 and 2996.9 MHz for the second one that are close to calculation results
A modified lower hybrid coupler for TPX
International Nuclear Information System (INIS)
Bernabei, S.; Greenough, N.
1995-01-01
Efforts have concentrated on redesigning the configuration of the Lower Hybrid coupler for TPX tokamak. Several concerns motivated this redesign: reduce the effect of thermal incompatibility between coupler and rf-window material, reduce weight, reduce the risk of wind failure and address the problem of replaceability, increase the reliability by reducing the number connections and finally, reduce the total cost. The result is a highly compact, light and easily serviceable coupler which incorporates some of the simplicity of the multifunction coupler but preserves the spectral flexibility of a conventional coupler
Fundamental Power Couplers for Superconducting Cavities
International Nuclear Information System (INIS)
Isidoro E. Campisi
2001-01-01
Fundamental power couplers (FPC's) for superconducting cavities must meet very strict requirements to perform at high power levels (hundreds of kilowatts) and in a variety of conditions (CS, pulsed, travelling wave, standing wave) without adversely affecting the performance of the cavities they are powering. Producing good coupler designs and achieving operational performances in accelerator environments are challenging tasks that have traditionally involved large resources from many laboratories. The designs involve state-of-the-art activities in RF, cryogenic and mechanical engineering, materials science, vacuum technology, and electromagnetic field modeling. Handling, assembly and conditioning procedures have been developed to achieve ever-increasing power levels and more reliable operation. In this paper, the technical issues associated with the design, construction, assembly, processing, and operation of FPC's will be reviewed, together with the progress in FPC activities in several laboratories during the past few years
High power test of RF window and coaxial line in vacuum
International Nuclear Information System (INIS)
Sun, D.; Champion, M.; Gormley, M.; Kerns, Q.; Koepke, K.; Moretti, A.
1993-01-01
Primary rf input couplers for the superconducting accelerating cavities of the TESLA electron linear accelerator test to be performed at DESY, Hamburg, Germany are under development at both DESY and Fermilab. The input couplers consist of a WR650 waveguide to coaxial line transition with an integral ceramic window, a coaxial connection to the superconducting accelerating cavity with a second ceramic window located at the liquid nitrogen heat intercept location, and bellows on both sides of the cold window to allow for cavity motion during cooldown, coupling adjustments and easier assembly. To permit in situ high peak power processing of the TESLA superconducting accelerating cavities, the input couplers are designed to transmit nominally 1 ms long, 2 MW peak, 1.3 GHz rf pulses from the WR650 waveguide at room temperature to the cavities at 1.8 K. The coaxial part of the Fermilab TESLA input coupler design has been tested up to 1.7 MW using the prototype 805 MHz rf source located at the A0 service building of the Tevatron. The rf source, the testing system and the test results are described
Energy Technology Data Exchange (ETDEWEB)
Souli, M. [Institut de Physique Nucleaire d' Orsay, CNRS/IN2P3, Orsay (France)]. E-mail: souli@ipno.in2p3.fr; Fouaidy, M. [Institut de Physique Nucleaire d' Orsay, CNRS/IN2P3, Orsay (France); Saugnac, H. [Institut de Physique Nucleaire d' Orsay, CNRS/IN2P3, Orsay (France); Szott, P. [Institut de Physique Nucleaire d' Orsay, CNRS/IN2P3, Orsay (France); Gandolfo, N. [Institut de Physique Nucleaire d' Orsay, CNRS/IN2P3, Orsay (France); Bousson, S. [Institut de Physique Nucleaire d' Orsay, CNRS/IN2P3, Orsay (France); Braud, D. [CEA Saclay, DSM/DAPNIA/SACM, 91191 Gif sur Yvette (France); Charrier, J.P. [CEA Saclay, DSM/DAPNIA/SACM, 91191 Gif sur Yvette (France); Roudier, D. [CEA Saclay, DSM/DAPNIA/SACM, 91191 Gif sur Yvette (France); Sahuquet, P. [CEA Saclay, DSM/DAPNIA/SACM, 91191 Gif sur Yvette (France); Visentin, B. [CEA Saclay, DSM/DAPNIA/SACM, 91191 Gif sur Yvette (France)
2006-07-15
The power coupler needed for {beta} = 0.65 SRF elliptical cavities dedicated to the driver of XADS (eXperimental Accelerator Driven System) should transmit a CW RF power of 150 kW to a 10 mA proton beam. The estimated average values of the RF losses in the coupler are 130 W (respectively 46 W) for the inner (respectively outer) conductor in SW mode. Due to such high values of the RF losses, it is necessary to very carefully design and optimize the cooling circuits of the coupler in order to efficiently remove the generated heat and to reduce the thermal load to the cavity operating at T = 2 K. An experiment simulating the thermal interaction between the power coupler and a 704 MHz SRF five cells cavity was performed in the CRYHOLAB test facility in order to determine the critical heat load that can be sustained by the cavity without degradation of its RF performance. Experimental data are compared to numerical simulation results obtained with the Finite Element Method code COSMOS/M. These data allow us also to perform in situ measurements of the thermal parameters needed in the thermal model of the coupler (thermal conductivity, thermal contact resistance). These data are used to validate numerical simulations.
The Design of a Five-Cell Superconducting RF Module with a PBG Coupler Cell
International Nuclear Information System (INIS)
Arsenyev, Sergey A.; Simakov, Evgenya I.
2012-01-01
We discuss the problem of incorporating a Photonic Band Gap (PBG) cell into a superconducting accelerating module of 5 cells designed for the operational frequency of 2.1 GHz. The reason for using a PBG cell is to provide a good accelerating mode confinement and good Higher Order Mode (HOM) suppression. PBG cell can potentially be used for placing HOM and fundamental mode couplers. However, because of the naturally higher ratio of the peak magnetic field to the accelerating field in the PBG cell, it should be designed to operate at a lower accelerating gradient than the other cells of the module. This ensures that the probability of quench in the PBG cell would be no higher than in other elliptical cells of the structure.
Study of the effect of loop inductance on the RF transmission line to cavity coupling coefficient
International Nuclear Information System (INIS)
Lal, Shankar; Pant, K. K.
2016-01-01
Coupling of RF power is an important aspect in the design and development of RF accelerating structures. RF power coupling employing coupler loops has the advantage of tunability of β, the transmission line to cavity coupling coefficient. Analytical expressions available in literature for determination of size of the coupler loop using Faraday’s law of induction show reasonably good agreement with experimentally measured values of β below critical coupling (β ≤ 1) but show large deviation with experimentally measured values and predictions by simulations for higher values of β. In actual accelerator application, many RF cavities need to be over-coupled with β > 1 for reasons of beam loading compensation, reduction of cavity filling time, etc. This paper discusses a modified analytical formulation by including the effect of loop inductance in the determination of loop size for any desired coupling coefficient. The analytical formulation shows good agreement with 3D simulations and with experimentally measured values. It has been successfully qualified by the design and development of power coupler loops for two 476 MHz pre-buncher RF cavities, which have successfully been conditioned at rated power levels using these coupler loops.
An RF input coupler system for the CEBAF energy upgrade cryomodule
International Nuclear Information System (INIS)
J.R. Delayen; L.R. Doolittle; T. Hiatt; J. Hogan; J. Mammosser; L. Phillips; J. Preble; W.J. Schneider; G. Wu
1999-01-01
Long term plans for CEBAF at Jefferson Lab call for achieving 12 GeV in the middle of the next decade and 24 GeV after 2010. Thus an upgraded cryomodule to more than double the present voltage is under development. A new waveguide coupler system has been designed and prototypes are currently being developed. This coupler, unlike the original, has a nominal Q ext of 2.1 x 10 7 , reduced sensitivity of Q ext to mechanical deformation, reduced field asymmetry within the beam envelope, freedom from window arcing with a single window at 300 K, and is capable of transmitting 6kW CW both traveling wave and in full reflection
Modeling and design of an X-band rf photoinjector
Directory of Open Access Journals (Sweden)
R. A. Marsh
2012-10-01
Full Text Available A design for an X-band rf photoinjector that was developed jointly by SLAC National Accelerator Laboratory (SLAC and Lawrence Livermore National Laboratory (LLNL is presented. The photoinjector is based around a 5.59 cell rf gun that has state-of-the-art features including: elliptical contoured irises; improved mode separation; an optimized initial half cell length; a racetrack input coupler; and coupling that balances pulsed heating with cavity fill time. Radio-frequency and beam dynamics modeling have been done using a combination of codes including PARMELA, HFSS, IMPACT-T, ASTRA, and the ACE3P suite of codes developed at SLAC. The impact of lower gradient operation, magnet misalignment, solenoid multipole errors, beam offset, mode beating, wakefields, and beam line symmetry have been analyzed and are described. Fabrication and testing plans at both LLNL and SLAC are discussed.
Linear collider RF structure design using ARGUS
International Nuclear Information System (INIS)
Kwok Ko
1991-01-01
In a linear collider, both the driving system (klystrons) and the accelerating system (linac) consists of RF structures that are inherently three-dimensional. These structures which are responsible for power input/output, have to satisfy many requirements in order that instabilities, beam or RF related, are to be avoided. At the same time, system efficiencies have to be maintained at optimal to minimize cost. Theoretical analysis on these geometrically complex structures are difficult and until recently, numerical solutions have been limited. At SLAC, there has been a continuing and close collaboration among accelerator physicists, engineers and numericists to integrate supercomputing into the design procedure which involves 3-D RF structures. The outcome is very encouraging. Using the 3-D/electromagnetic code ARGUS (developed by SAIC) on the Cray computers at NERSC in conjunction with supporting theories, a wide variety of critical components have been simulated and evaluated. Aside from structures related to the linear collider, the list also includes the RF cavity for the proposed Boson Factory and the anode circuit for the Cross-Field Amplifier, once considered as an alternative to the klystron as a possible power source. This presentation will focus on two specific structures: (1) the klystron output cavity; and (2) the linac input coupler. As the results demonstrate, supercomputing is fast becoming a viable technology that could conceivably replace actual cold-testing in the near future
Design of an rf quadrupole for Landau damping
Papke, K.; Grudiev, A.
2017-08-01
The recently proposed superconducting quadrupole resonator for Landau damping in accelerators is subjected to a detailed design study. The optimization process of two different cavity types is presented following the requirements of the High Luminosity Large Hadron Collider (HL-LHC) with the main focus on quadrupolar strength, surface peak fields, and impedance. The lower order and higher order mode (LOM and HOM) spectrum of the optimized cavities is investigated and different approaches for their damping are proposed. On the basis of an example the first two higher order multipole errors are calculated. Likewise on this example the required rf power and optimal external quality factor for the input coupler is derived.
High-power tests of a single-cell copper accelerating cavity driven by two input couplers
International Nuclear Information System (INIS)
Horan, D.; Bromberek, D.; Meyer, D.; Waldschmidt, G.
2008-01-01
High-power tests were conducted on a 350-MHz, single-cell copper accelerating cavity driven simultaneously by two H-loop input couplers for the purpose of determining the reliability, performance, and power-handling capability of the cavity and related components, which have routinely operated at 100-kW power levels. The test was carried out utilizing the APS 350-MHz RF Test Stand, which was modified to split the input rf power into two frac12-power feeds, each supplying power to a separate H-loop coupler on the cavity. Electromagnetic simulations of the two-coupler feed system were used to determine coupler match, peak cavity fields, and the effect of phasing errors between the coupler feed lines. The test was conducted up to a maximum total rf input power of 164-kW CW. Test apparatus details and performance data will be presented.
High power RF test of an 805 MHz RF cavity for a muon cooling channel
International Nuclear Information System (INIS)
Li, Derun; Corlett, J.; MacGill, R.; Rimmer, R.; Wallig, J.; Zisman, M.; Moretti, A.; Qian, Z.; Wu, V.; Summers, D.; Norem, J.
2002-01-01
We present recent high power RF test results on an 805 MHz cavity for a muon cooling experiment at Lab G in Fermilab. In order to achieve high accelerating gradient for large transverse emittance muon beams, the cavity design has adopted a pillbox like shape with 16 cm diameter beam iris covered by thin Be windows, which are demountable to allow for RF tests of different windows. The cavity body is made from copper with stiff stainless steel rings brazed to the cavity body for window attachments. View ports and RF probes are available for visual inspections of the surface of windows and cavity and measurement of the field gradient. Maximum of three thermo-couples can be attached to the windows for monitoring the temperature gradient on the windows caused by RF heating. The cavity was measured to have Q 0 of about 15,000 with copper windows and coupling constant of 1.3 before final assembling. A 12 MW peak power klystron is available at Lab G in Fermilab for the high power test. The cavity and coupler designs were performed using the MAFIA code in the frequency and the time domain. Numerical simulation results and cold test measurements on the cavity and coupler will be presented for comparisons
Energy Technology Data Exchange (ETDEWEB)
J. Shi; H. Chen; S. Zheng; D. Li; R.A. Rimmer; H. Wang
2006-06-26
Accurate predications of RF coupling between an RF cavity and ports attached to it have been an important study subject for years for RF coupler and higher order modes (HOM) damping design. We report recent progress and a method on the RF coupling simulations between waveguide ports and RF cavities using CST Microwave Studio in time domain (Transit Solver). Comparisons of the measured and calculated couplings are presented. The simulated couplings and frequencies agree within {approx} 10% and {approx} 0.1% with the measurements, respectively. We have simulated couplings with external Qs ranging from {approx} 100 to {approx} 100,000, and confirmed with measurements. The method should also work well for higher Qs, and can be easily applied in RF power coupler designs and HOM damping for normal-conducting and superconducting cavities.
International Nuclear Information System (INIS)
J. Shi; H. Chen; S. Zheng; D. Li; R.A. Rimmer; H. Wang
2006-01-01
Accurate predications of RF coupling between an RF cavity and ports attached to it have been an important study subject for years for RF coupler and higher order modes (HOM) damping design. We report recent progress and a method on the RF coupling simulations between waveguide ports and RF cavities using CST Microwave Studio in time domain (Transit Solver). Comparisons of the measured and calculated couplings are presented. The simulated couplings and frequencies agree within ∼ 10% and ∼ 0.1% with the measurements, respectively. We have simulated couplings with external Qs ranging from ∼ 100 to ∼ 100,000, and confirmed with measurements. The method should also work well for higher Qs, and can be easily applied in RF power coupler designs and HOM damping for normal-conducting and superconducting cavities
Souli, M.; Fouaidy, M.; Hammoudi, N.
2010-05-01
The coaxial power coupler needed for beta = 0.65 superconducting RF cavities used in the high energy section of the EUROTRANS driver should transmit 150 kW (CW operation) RF power to the proton beam. The estimated RF losses on the power coupler outer conductor in standing wave mode operation are 46 W. To remove these heat loads, a full scale copper coil heat exchanger brazed around the outer conductor was designed and tested using supercritical helium at T = 6 K as a coolant. Our main objective was to minimise the heat loads to cold extremity of SRF cavity maintained at 2 K or 4.2 K. A dedicated test facility named SUPERCRYLOOP was developed and successfully operated in order to measure the performance of the cold heat exchanger. The test cell used reproduces the realistic thermal boundary conditions of the power coupler mounted on the cavity in the cryomodule. After a short introduction, a brief discussion about the problem of power coupler cooling systems in different machines is made. After that, we describe the experimental set-up and test apparatus. Then, a heat exchanger thermal model will be developed with FEM code COSMOS/M to estimate the different heat transfer coefficients by comparison between numerical simulation results and experimental data in order to validate the design. Finally, thermo-hydraulic behavior of supercritical helium has been investigated as function of different parameters (inlet pressure, flow rate, heat loads).
Design of an rf quadrupole for Landau damping
Directory of Open Access Journals (Sweden)
K. Papke
2017-08-01
Full Text Available The recently proposed superconducting quadrupole resonator for Landau damping in accelerators is subjected to a detailed design study. The optimization process of two different cavity types is presented following the requirements of the High Luminosity Large Hadron Collider (HL-LHC with the main focus on quadrupolar strength, surface peak fields, and impedance. The lower order and higher order mode (LOM and HOM spectrum of the optimized cavities is investigated and different approaches for their damping are proposed. On the basis of an example the first two higher order multipole errors are calculated. Likewise on this example the required rf power and optimal external quality factor for the input coupler is derived.
Multipacting study of the RF window at the Advanced Photon Source (APS)
International Nuclear Information System (INIS)
Song, J. J.
1999-01-01
Multipacting current can cause breakdowns in high power rf components such as input couplers, waveguide windows, and higher-order mode (HOM) dampers. To understand and prevent the loss of a ceramic window or an input coupler in the Advanced Photon Source (APS) storage ring rf cavity, the multipacting phenomenon is being investigated experimentally. This paper begins with a description of simple model, presents a hardware design, and concludes with measurement of multipacting. Multipacting is explored in conjunction with conditioning the cavities and interaction with the stored beam
Thermal behaviour analysis of SRF cavities and superconducting HOM couplers
International Nuclear Information System (INIS)
Fouaidy, M.; Junquera, T.
1993-01-01
Two individual papers appear in this report, titled Thermal model calculations in superconducting RF cavities, and Thermal study of HOM couplers for superconducting RF cavities. Both were indexed separately for the INIS database. (R.P.)
Thermal-Mechanical Study of 3.9 GHz CW Coupler and Cavity for LCLS-II Project
Energy Technology Data Exchange (ETDEWEB)
Gonin, Ivan [Fermilab; Harms, Elvin [Fermilab; Khabiboulline, Timergali [Fermilab; Solyak, Nikolay [Fermilab; Yakovlev, Vyacheslav [Fermilab
2017-05-01
Third harmonic system was originally developed by Fermilab for FLASH facility at DESY and then was adopted and modified by INFN for the XFEL project [1-3]. In contrast to XFEL project, all cryomodules in LCLS-II project will operate in CW regime with higher RF average power for 1.3 GHz and 3.9 GHz cavities and couplers. Design of the cavity and fundamental power coupler has been modified to satisfy LCLS-II requirements. In this paper we discuss the results of COMSOL thermal and mechanical analysis of the 3.9 GHz coupler and cavity to verify proposed modifica-tion of the design. For the dressed cavity we present simulations of Lorentz force detuning, helium pressure sensitivity df/dP and major mechanical resonances.
Design Considerations for the LHC 200 MHz RF System
Boussard, Daniel; Kindermann, H P; Linnecar, Trevor Paul R; Marque, S; Tückmantel, Joachim
2000-01-01
The longitudinal beam transfer from the SPS into the LHC 400 MHz buckets will not be free of losses without a lower frequency capture system and a fast longitudinal damping system in LHC. We present a complete study of a combined system using four identical copper cavities at 200 MHz delivering 3 MV total CW voltage and having still enough bandwidth to achieve fast longitudinal damping. The shape of a cavity was designed according to the accelerating mode performance, its tuning and the higher order mode spectrum with respect to the LHC beam lines and their possible attenuation. The possibility to park the cavities during coast was included. The local heat load and the corresponding cooling water distribution as well as deformations were studied and techniques to build the cavity with all ports at low cost are proposed. The parameters of the RF generators, couplers and detuning are determined. Simulations of the total LHC RF system incorporating real delays, generator bandwidth and the control loops confirm t...
Dal Forno, Massimo; Craievich, Paolo; Penco, Giuseppe; Vescovo, Roberto
2013-11-01
The front-end injection systems of the FERMI@Elettra linac produce high brightness electron beams that define the performance of the Free Electron Laser. The photoinjector mainly consists of the radiofrequency (rf) gun and of two S-band rf structures which accelerate the beam. Accelerating structures endowed with a single feed coupler cause deflection and degradation of the electron beam properties, due to the asymmetry of the electromagnetic field. In this paper, a new type of single feed structure with movable short-circuit is proposed. It has the advantage of having only one waveguide input, but we propose a novel design where the dipolar component is reduced. Moreover, the racetrack geometry allows to reduce the quadrupolar component. This paper presents the microwave design and the analysis of the particle motion inside the linac. A prototype has been machined at the Elettra facility to verify the new coupler design and the rf field has been measured by adopting the bead-pull method. The results are here presented, showing good agreement with the expectations.
International Nuclear Information System (INIS)
Forno, Massimo Dal; Craievich, Paolo; Penco, Giuseppe; Vescovo, Roberto
2013-01-01
The front-end injection systems of the FERMI@Elettra linac produce high brightness electron beams that define the performance of the Free Electron Laser. The photoinjector mainly consists of the radiofrequency (rf) gun and of two S-band rf structures which accelerate the beam. Accelerating structures endowed with a single feed coupler cause deflection and degradation of the electron beam properties, due to the asymmetry of the electromagnetic field. In this paper, a new type of single feed structure with movable short-circuit is proposed. It has the advantage of having only one waveguide input, but we propose a novel design where the dipolar component is reduced. Moreover, the racetrack geometry allows to reduce the quadrupolar component. This paper presents the microwave design and the analysis of the particle motion inside the linac. A prototype has been machined at the Elettra facility to verify the new coupler design and the rf field has been measured by adopting the bead-pull method. The results are here presented, showing good agreement with the expectations
Comparison of coaxial higher order mode couplers for the CERN Superconducting Proton Linac study
Directory of Open Access Journals (Sweden)
K. Papke
2017-06-01
Full Text Available Higher order modes (HOMs may affect beam stability and refrigeration requirements of superconducting proton linacs such as the Superconducting Proton Linac, which is studied at CERN. Under certain conditions beam-induced HOMs can accumulate sufficient energy to destabilize the beam or quench the superconducting cavities. In order to limit these effects, CERN considers the use of coaxial HOM couplers on the cutoff tubes of the 5-cell superconducting cavities. These couplers consist of resonant antennas shaped as loops or probes, which are designed to couple to potentially dangerous modes while sufficiently rejecting the fundamental mode. In this paper, the design process is presented and a comparison is made between various designs for the high-beta SPL cavities, which operate at 704.4 MHz. The rf and thermal behavior as well as mechanical aspects are discussed. In order to verify the designs, a rapid prototype for the favored coupler was fabricated and characterized on a low-power test-stand.
Comparison of coaxial higher order mode couplers for the CERN Superconducting Proton Linac study
AUTHOR|(CDS)2085329; Gerigk, Frank; Van Rienen, Ursula
2017-01-01
Higher order modes (HOMs) may affect beam stability and refrigeration requirements of superconducting proton linacs such as the Superconducting Proton Linac, which is studied at CERN. Under certain conditions beam-induced HOMs can accumulate sufficient energy to destabilize the beam or quench the superconducting cavities. In order to limit these effects, CERN considers the use of coaxial HOM couplers on the cutoff tubes of the 5-cell superconducting cavities. These couplers consist of resonant antennas shaped as loops or probes, which are designed to couple to potentially dangerous modes while sufficiently rejecting the fundamental mode. In this paper, the design process is presented and a comparison is made between various designs for the high-beta SPL cavities, which operate at 704.4 MHz. The rf and thermal behavior as well as mechanical aspects are discussed. In order to verify the designs, a rapid prototype for the favored coupler was fabricated and characterized on a low-power test-stand.
Design and rf tuning of the KEK 40 MeV proton linear accelerator
International Nuclear Information System (INIS)
Kato, Takao.
1986-09-01
An Alvarez linac was designed and constructed on the basis of a model linac study to increase the output energy from 20 to 40 MeV. The linac was tuned by frequency tuners and post couplers. Stabilization of the field was achieved and a variation within ± 0.7 % of the accelerating field was obtained. An equivalent circuit analysis which can numerically solve loop equations, including stem and post currents in addition to tank current, can explain the rf characteristics of a postcoupled structure. (author)
Application of RF Superconductivity to High-Current Linac
International Nuclear Information System (INIS)
Chan, K.C.D.
1998-01-01
In 1997, the authors initiated a development program in Los Alamos for high-current superconducting proton-linac technology to build prototypes components of this linac to demonstrate the feasibility. The authors are building 700-MHz niobium cavities with elliptical shapes, as well as power couplers to transfer high RF power to these cavities. The cavities and power couplers will be integrated in cryostats as linac cryomodules. In this paper, they describe the linac design and the status of the development program
Development of 650 MHz solid state RF amplifier for proton accelerator
International Nuclear Information System (INIS)
Jain, Akhilesh; Sharma, Deepak; Gupta, Alok; Tiwari, Ashish; Rao, Nageswar; Sekar, Vasanthi; Lad, M.; Hannurkar, P.R.; Gupta, P.D.
2011-01-01
Design and development of 30 kW high powers RF source at 650 MHz, using solid RF state technology, has been initiated at RRCAT. The indigenous technology development efforts will be useful for the proposed high power proton accelerators for SNS/ADS applications. In this 650 MHz amplifier scheme, 30 kW CW RF power will be generated using modular combination of 8 kW amplifier units. Necessary studies were carried out for device selection, choice of amplifier architecture and design of high power combiners and dividers. Presently RF amplifier delivering 250 W at 650 MHz has been fabricated and tested. Towards development of high power RF components, design and engineering prototyping of 16-port power combiner, directional coupler and RF dummy loads has been completed. The basic 8 kW amplifier unit is designed to provide power gain of 50 dB, bandwidth of 20 MHz and spurious response below 30 dB from fundamental signal. Based on the results of circuit simulation studies and engineering prototyping of amplifier module, two RF transistor viz. MRF3450 and MRF 61K were selected as solid state active devices. Impedance matching network in amplifier module is designed using balanced push pull configuration with transmission line BALUN. Due to high circulating current near drain side, metal clad RF capacitors were selected which helps in avoiding hot spot from output transmission path, ensuring continuous operation at rated RF power without damage to RF board. 350 W circulator is used to protect the RF devices from reflected power. Based on the prototype design and measured performance, one of these RF transistors will be selected to be used as workhorse for all amplifier modules. Two amplifier modules are mounted on water cooled copper heat-sink ensuring proper operating temperature for reliable and safe operation of amplifier. Also real time control system and data logger has been developed to provide DAQ and controls in each rack. For power combining and power measurement
Energy Technology Data Exchange (ETDEWEB)
Jenhani, Hassen [Laboratoire de l' Accelerateur Lineaire, IN2P3-CNRS et Universite de Paris-Sud, BP 34, F-91898 Orsay Cedex (France)
2006-11-15
Recent years have seen an impressive improvement in the accelerating gradients obtained in superconducting cavities. Consequently, such cavities have become attractive candidates for large superconducting linear accelerator projects such as the European XFEL and the International Linear Collider (ILC). As a result, there is a strong interest in reducing RF conditioning time and improving the performance of the input power couplers for these cavities. The so-called TTF-III input power coupler, adopted for the XFEL superconducting RF cavities are complex components. In order to better understand the behavior of this component we have performed a series of experiments on a number of such couplers. Initially, we developed a fully automated RF high power test stand for coupler conditioning procedure. Following this, we performed a series of coupler conditioning tests. This has allowed the study of the coupler behavior during processing. A number of experiments were carried out to evaluate the in-situ baking effect on the conditioning time. Some of the conditioned couplers were sent to DESY in order to be tested on 9-cells TESLA cavities under cryogenic conditions. These tests have shown that the couplers in no way limit the cavity performance, even up to gradients of 35 MV/m. The main objective of our coupler studies was the reduction of their conditioning time, which represents one of the most important criteria in the choice of coupler for high energy linacs. Excellent progress in reducing the conditioning time has been demonstrated by making appropriate modifications to the conditioning procedure. Furthermore, special attention was paid to electron generation processes in the couplers, via multipacting. Simulations of this process were made on both the TTF-III coupler and on a new coupler prototype, TTF-V. Experiments aimed at suppressing multipacting were also successfully achieved by using a DC bias on the inner conductor of the co-axial coupler. (author)
Design and fabrication of multimode interference couplers based on digital micro-mirror system
Wu, Sumei; He, Xingdao; Shen, Chenbo
2008-03-01
Multimode interference (MMI) couplers, based on the self-imaging effect (SIE), are accepted popularly in integrated optics. According to the importance of MMI devices, in this paper, we present a novel method to design and fabricate MMI couplers. A technology of maskless lithography to make MMI couplers based on a smart digital micro-mirror device (DMD) system is proposed. A 1×4 MMI device is designed as an example, which shows the present method is efficient and cost-effective.
Blanco, Esteban
2016-01-01
A superconducting 800 MHz second harmonic RF system is one of the considered options as a Landau damping mechanism for HiLumi LHC. The Higher Order Mode (HOM) coupler designs require tight manufacturing tolerances in order to operate at the design specifications. The project consists of defining the mechanical tolerances for the different components of both the probe-type and hook-type HOM coupler. With the use of electromagnetic field simulation software it is possible to identify the critical components of the HOM coupler and to quantify their respective tolerances. The obtained results are discussed in this paper.
Passive and active RF-microwave circuits course and exercises with solutions
Jarry, Pierre
2015-01-01
Microwave and radiofrequency (RF) circuits play an important role in communication systems. Due to the proliferation of radar, satellite, and mobile wireless systems, there is a need for design methods that can satisfy the ever increasing demand for accuracy, reliability, and fast development times. This book explores the principal elements for receiving and emitting signals between Earth stations, satellites, and RF (mobile phones) in four parts; the theory and realization of couplers, computation and realization of microwave and RF filters, amplifiers and microwave and RF oscillators. Pas
RF tuning system for superconducting cyclotron at VECC
International Nuclear Information System (INIS)
Mandal, Aditya; Som, S.; Pal, Saikat; Seth, S.; Mukherjee, A.K.; Gangopadhyay, P.; Prasad, J.S.; Raj, P.R.; Manna, S.K.; Banerjee, M.; Krishnaiah, K.V.; Maskawade, S.; Saha, M.S.; Biswas, S.; Panda, Umashakar
2009-01-01
The RF system of Superconducting cyclotron at VECC has operational frequency 9-27 MHz. It has three numbers of tunable rf amplifier cavities as well as six numbers of tunable Main resonant cavities. RF tuning system takes care of movement of nine stepper motor based sliding short movement and hydraulic driven three coupling capacitors and three trimmer capacitors. The PC-based stepper motor controlled sliding short movement system has positional accuracy of around 20 micron and PC-based hydraulically driven couplers and trimmers system has 10 micron positional accuracy. The RF power is capacitively coupled to the dee (accelerating electrode) of the main resonant cavity through Coupler (Coupling capacitor). The coupling capacitor is used to match the impedance of the main resonant cavity to the 50 Ohm output impedance of final RF power amplifier. Trimmer capacitor operates in closed loop for the adjustment of cavity phase variation arising due to temperature variation and beam loading of the cavity. Coupler can travel 100 mm. and trimmer has 20 mm. travels. A PLC based PID control system has been developed for positional control of the coupler and trimmer. One position control mode of trimmer is same as coupling capacitor and another is velocity control mode. Velocity control mode operates in close-loop. The positional data of different frequencies of nine stepper motors and three coupling capacitors are stored in a database. (author)
Energy Technology Data Exchange (ETDEWEB)
Park, S. Y.; Kim, H. J.; Wi, H. H.; Wang, S. J.; Kwak, J. G. [NFRI, Daejeon (Korea, Republic of)
2016-05-15
200 kW RF power will be injected to plasmas through the traveling wave antenna after combining four klystrons output powers using three hybrid combiners. Each klystron produces 60 kW output at the frequency of 500 MHz. RF power combiners commonly used to divide or combine output powers for various rf and microwave applications. It is divided into several types according to the design type such as Wilkinson combiner, radial and quadrature hybrid combiner. We designed high power hybrid combiners using 6-1/8 inch coaxial line. The power combiner has many advantages such as high isolation, low insertion loss and high power handling capability. In this paper design and rf test results of high power combiners will be described. High power combiners using three coaxial hybrid couplers will be utilized for effectively combining of 500 MHz, 200 kW output powers generated by four klystrons. We have designed, fabricated, and tested a 6-1/8 inch coaxial hybrid combiners at 500 MHz for efficiently off-axis Helicon wave current drive in KSTAR. Simulation and test results of high power coaxial hybrid combiners are good agreement.
Design of the new couplers for C-ADS RFQ
Shi, Ai-Min; Sun, Lie-Peng; Zhang, Zhou-Li; Xu, Xian-Bo; Shi, Long-Bo; Li, Chen-Xing; Wang, Wen-Bin
2015-04-01
A new special coupler with a kind of bowl-shaped ceramic window for a proton linear accelerator named the Chinese Accelerator Driven System (C-ADS) at the Institute of Modern Physics (IMP) has been simulated and constructed and a continuous wave (CW) beam commissioning through a four-meter long radio frequency quadruple (RFQ) was completed by the end of July 2014. In the experiments of conditioning and beam, some problems were promoted gradually such as sparking and thermal issues. Finally, two new couplers were passed with almost 110 kW CW power and 120 kW pulsed mode, respectively. The 10 mA intensity beam experiments have now been completed, and the couplers during the operation had no thermal or electro-magnetic problems. The detailed design and results are presented in the paper. Supported by Strategic Priority Research Program of Chinese Academy of Sciences (XDA03020500)
Low-crosstalk orbital angular momentum fiber coupler design.
Zhang, Zhishen; Gan, Jiulin; Heng, Xiaobo; Li, Muqiao; Li, Jiong; Xu, Shanhui; Yang, Zhongmin
2017-05-15
A fiber coupler for low-crosstalk orbital angular momentum mode beam splitter is proposed with the structure of two separate and parallel microfibers. By properly setting the center-to-center distance between microfibers, the crosstalk is less than -20 dB, which means that the purity of the needed OAM mode in output port is higher than 99%. For a fixed overlapping length, high coupling efficiency (>97%) is achieved in 1545-1560 nm. The operating wavelength is tuned to the whole C-band by using the thermosensitive liquid. So the designed coupler can achieve the tunable coupling ratio over the whole C-band, which is a prospective component for the further OAM fiber system.
International Nuclear Information System (INIS)
M. Stirbet; I.E. Campisi; E.F. Daly; G.K. Davis; M. Drury; P. Kneisel; G. Myneni; T. Powers; W.J. Schneider; K.M. Wilson; Y. Kang; K.A. Cummings; T. Hardek
2001-01-01
High-power RF testing with peak power in excess of 500 kW has been performed on prototype Fundamental Power Couplers (FPC) for the Spallation Neutron Source superconducting (SNS) cavities. The testing followed the development of procedures for cleaning, assembling and preparing the FPC for installation in the test stand. The qualification of the couplers has occurred for the time being only in a limited set of conditions (travelling wave, 20 pps) as the available RF system and control instrumentation are under improvement
High-power RF cavity R ampersand D for the PEP-II B Factory
International Nuclear Information System (INIS)
Rimmer, R.; Lambertson, G.; Hodgson, J.
1994-06-01
We describe the development of a high-power test model of the 476 MHz RF cavity for the PEP-II B Factory. This cavity is designed to demonstrate the feasibility of a high-power design with higher-order mode (HOM) damping waveguides and the fabrication technologies involved, and it can also be used to evaluate aperture or loop couplers and various RF windows. Changes to the RF design to reduce peak surface heating are discussed and results of finite-element analyses of temperature and stress are presented. Fabrication methods for the prototype and subsequent production cavities are discussed
Design and optimization of mechanically down-doped terahertz fiber directional couplers
DEFF Research Database (Denmark)
Bao, Hualong; Nielsen, Kristian; Rasmussen, Henrik K.
2014-01-01
We present a thorough practical design optimization of broadband low loss, terahertz (THz) photonic crystal fiber directional couplers in which the two cores are mechanically down-doped with a triangular array of air holes. A figure of merit taking both the 3-dB bandwidth and loss of the coupler...... into account, is used for optimization of the structure parameters, given by the diameter and pitch of the cladding (d and Λ) and of the core (dc and Λc) air-hole structure. The coupler with Λ = 498.7 μm, dc= 324.2 μm, Λc = 74.8 μm, and dc = 32.5 μm is found to have the best performance at a center frequency...... of 1THz, with a bandwidth of 0.25 THz and a total device loss of 9.2 dB. The robustness of the optimum coupler to structural changes is investigated. © 2014 Optical Society of America....
International Nuclear Information System (INIS)
Lynch, M.; Kwon, S.
2001-01-01
A high-intensity proton linac, such as that being planned for the SNS, requires accurate RF control of cavity fields for the entire pulse in order to avoid beam spill. The current design requirement for the SNS is RF field stability within ±0.5% and ±0.5 o [1]. This RF control capability is achieved by the control electronics using the excess RF power to correct disturbances. To minimize the initial capital costs, the RF system is designed with 'just enough' RF power. All the usual disturbances exist, such as beam noise, klystron/HVPS noise, coupler imperfections, transport losses, turn-on and turn-off transients, etc. As a superconducting linac, there are added disturbances of large magnitude, including Lorentz detuning and microphonics. The effects of these disturbances and the power required to correct them are estimated, and the result shows that the highest power systems in the SNS have just enough margin, with little or no excess margin
Frischholz, Hans; Pearson, C
1998-01-01
A 500 kW cw klystron operating at 400 MHz was developed and constructed jointly by CERN and SLAC for use as a high-power source at CERN for testing LHC/RF components such as circulators, RF absorbers and superconducting cavities with their input couplers. The design is a modification of the 353 MHz SLAC PEP-I klystron. More than 80% of the original PEP-I tube parts could thus be incorporated in the LHC test klystron which resulted in lower engineering costs as well as reduced development and construction time. The physical length between cathode plane and upper pole plate was kept unchanged so that a PEP-I tube focusing solenoid, available at CERN, could be re-used. With the aid of the klystron simulation codes JPNDISK and CONDOR, the design of the LHC tube was accomplished, which resulted in a tube with noticeably higher efficiency than its predecessor, the PEP-I klystron. The integrated cavities were redesigned using SUPERFISH and the output coupling circuit, which also required redesigning, was done with t...
Measuring the performance of the coaxial HOM coupler on a 2-cell TESLA-shape copper cavity
International Nuclear Information System (INIS)
Wang Fang; Wang Erdong; Zhang Baocheng; Zhao Kui
2009-01-01
Coaxial High Order Mode (HOM) couplers have been fabricated at Peking University and their RF performance has been measured on a test device consisting of a coaxial transmission line and a 2-cell TESLA-shape copper cavity. The test results on the 2-cell TESLA-shape copper cavity with HOM couplers indicate that the coupler can cut off the fundamental mode TM 010 and absorb HOMs effectively after a careful adjustment. The optimal angle of the HOM coupler with the beam tube is found. The initial test results of HOM couplers are presented in this paper. (authors)
High power RF systems for LEHIPA of ADS
International Nuclear Information System (INIS)
Pande, Manjiri; Shrotriya, Sandip; Sharma, Sonal; Rao, B.V.R.; Mishra, J.K.; Patel, Niranjan; Gupta, S.K.
2011-01-01
Worldwide accelerator driven sub-critical system (ADS) has generated a huge interest for various reasons. In India, as a part of accelerator driven sub-critical system (ADS) program, a normal conducting, low energy high intensity proton accelerator (LEHIPA) of energy 20 MeV and beam current of 30 mA is being developed in Bhabha Atomic Research Centre (BARC). LEHIPA comprises of Electron Cyclotron Resonance (ECR) ion source (50 KeV), Radio Frequency Quadrupole (RFQ) accelerator (3 MeV) and Drift tube Linac (DTL) 1 and 2 (10 MeV and 20 MeV respectively). As per the accelerator physics design, RFQ requires nearly 530 kW RF power while each of DTL need 900 kW. Each accelerating cavity will be driven by a one- megawatt (CW) klystron based high power RF (HPRF) system at 352.21 MHz. Three such RF systems will be developed. The RF system has been designed around five cavity klystron tube TH2089F (Thales make) capable of delivering 1 MW continuous wave power at 352.21 MHz. The klystron has a gain of 40 dB and efficiency around 62 %. Each of the RF system comprises of a low power solid state driver (∼ 100 W), klystron tube, harmonic filter, directional coupler, Y-junction circulator (AFT make), RF load and WR2300 wave guide based RF transmission line each of 1 MW capacity. It also includes other subsystems like bias supplies (high voltage (HV) and low voltage (LV)), HV interface system, interlock and protection circuits, dedicated low conductivity water-cooling, pulsing circuitry/mechanisms etc. WR 2300 based RF transmission line transmits and feeds the RE power from klystron source to respective accelerating cavity. This transmission line starts from second port of the circulator and consists of straight sections, full height to half height transition, magic Tee, termination load at the centre of magic tee, half height sections, directional couplers and RE windows. For X-ray shielding, klystron will be housed in a lead (3 mm) based shielded cage. This system set up has a
Mechanical Design and Fabrication of a New RF Power Amplifier for LANSCE
International Nuclear Information System (INIS)
Chen, Zukun
2011-01-01
A Full-scale prototype of a new 201.25 MHz RF Final Power Amplifier (FPA) for Los Alamos Neutron Science Center (LANSCE) has been designed, fabricated, assembled and installed in the test facility. This prototype was successfully tested and met the physics and electronics design criteria. The team faced design and manufacturing challenges, having a goal to produce 2 MW peak power at 13% duty factor, at the elevation of over 2 km in Los Alamos. The mechanical design of the final power amplifier was built around a Thales TH628 Diacrode R , a state-of-art tetrode power tube. The main structure includes Input circuit, Output circuit, Grid decoupling circuit, Output coupler, Tuning pistons, and a cooling system. Many types of material were utilized to make this new RF amplifier. The fabrication processes of the key components were completed in the Prototype Fabrication Division shop at Los Alamos National Laboratory. The critical plating procedures were achieved by private industry. The FPA mass is nearly 600 kg and installed in a beam structural support stand. In this paper, we summarize the FPA design basis and fabrication, plating, and assembly process steps with necessary lifting and handling fixtures. In addition, to ensure the quality of the FPA support structure a finite element analysis with seismic design forces has also been carried out.
Mechanical Design and Fabrication of a New RF Power Amplifier for LANSCE
Energy Technology Data Exchange (ETDEWEB)
Chen, Zukun [Los Alamos National Laboratory
2011-01-01
A Full-scale prototype of a new 201.25 MHz RF Final Power Amplifier (FPA) for Los Alamos Neutron Science Center (LANSCE) has been designed, fabricated, assembled and installed in the test facility. This prototype was successfully tested and met the physics and electronics design criteria. The team faced design and manufacturing challenges, having a goal to produce 2 MW peak power at 13% duty factor, at the elevation of over 2 km in Los Alamos. The mechanical design of the final power amplifier was built around a Thales TH628 Diacrode{sup R}, a state-of-art tetrode power tube. The main structure includes Input circuit, Output circuit, Grid decoupling circuit, Output coupler, Tuning pistons, and a cooling system. Many types of material were utilized to make this new RF amplifier. The fabrication processes of the key components were completed in the Prototype Fabrication Division shop at Los Alamos National Laboratory. The critical plating procedures were achieved by private industry. The FPA mass is nearly 600 kg and installed in a beam structural support stand. In this paper, we summarize the FPA design basis and fabrication, plating, and assembly process steps with necessary lifting and handling fixtures. In addition, to ensure the quality of the FPA support structure a finite element analysis with seismic design forces has also been carried out.
Egan, William F
2003-01-01
he ultimate practical resource for today's RF system design professionals Radio frequency components and circuits form the backbone of today's mobile and satellite communications networks. Consequently, both practicing and aspiring industry professionals need to be able to solve ever more complex problems of RF design. Blending theoretical rigor with a wealth of practical expertise, Practical RF System Design addresses a variety of complex, real-world problems that system engineers are likely to encounter in today's burgeoning communications industry with solutions that are not easily available in the existing literature. The author, an expert in the field of RF module and system design, provides powerful techniques for analyzing real RF systems, with emphasis on some that are currently not well understood. Combining theoretical results and models with examples, he challenges readers to address such practical issues as: * How standing wave ratio affects system gain * How noise on a local oscillator will affec...
Energy Technology Data Exchange (ETDEWEB)
Arsenyev, Sergey Andreyevich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Simakov, Evgenya Ivanovna [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Shchegolkov, Dmitry [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Boulware, Chase [Niowave, Lansing, MI (United States); Grimm, Terry [Niowave, Lansing, MI (United States); Rogacki, Adam [Niowave, Lansing, MI (United States)
2015-04-29
We report the design and experimental data for a copper prototype of a superconducting radio-frequency (SRF) accelerator module. The five-cell module has an incorporated photonic band gap (PBG) cell with couplers. The purpose of the PBG cell is to achieve better higher order mode (HOM) damping, which is vital for preserving the quality of high-current electron beams. Better HOM damping raises the current threshold for beam instabilities in novel SRF accelerators. The PBG design also increases the real-estate gradient of the linac because both HOM damping and the fundamental power coupling can be done through the PBG cell instead of on the beam pipe via complicated end assemblies. First, we will discuss the design and accelerating properties of the structure. The five-cell module was optimized to provide good HOM damping while maintaining the same accelerating properties as conventional elliptical-cell modules. We will then discuss the process of tuning the structure to obtain the desired accelerating gradient profile. Finally, we will list measured quality factors for the accelerating mode and the most dangerous HOMs.
WAVEGUIDE COUPLER KICK TO BEAM BUNCH AND CURRENT DEPENDENCY ON SRF CAVITIES
International Nuclear Information System (INIS)
Genfa Wu; Haipeng Wang; Charles Reece; Robert Rimmer
2008-01-01
JLAB SRF cavities employ waveguide type fundamental power couplers (FPC). The FPC design for the 7-cell upgrade cavities was optimized to minimize the dipole field kick. For continuous wave (CW) operation, the forwarding RF power will be at different magnitude to drive the different beam current and cavity gradient. This introduces some deviation from optimized FPC field for varying beam loading. This article analyzes the beam behavior both in centroid kick and head-tail kick under different beam loading conditions
ANSYS modeling of thermal contraction of SPL HOM couplers during cool-down
Papke, K
2016-01-01
During the cool-down the HOM coupler as well as the cavity inside the cryo module experience a thermal contraction. For most materials between room temperature and liquid helium temperatures, the changes in dimension are in the order of a few tenths of a percent change in volume. This paper presents the effect of thermal contraction on the RF transmission behavior of HOM couplers, and in particular the influence on its notch filter. Furthermore the simulation process with APDL is explained in detail. Conclusions about the necessary tuning range of the notch filter are made which is especially a concern for couplers with only notch filter.
Analysis and design of arrayed waveguide gratings with MMI couplers.
Munoz, P; Pastor, D; Capmany, J
2001-09-24
We present an extension of the AWG model and design procedure described in [1] to incorporate multimode interference, MMI, couplers. For the first time to our knowledge, a closed formula for the passing bands bandwidth and crosstalk estimation plots are derived.
Design of Dual-Band Two-Branch-Line Couplers with Arbitrary Coupling Coefficients in Bands
Directory of Open Access Journals (Sweden)
I. Prudyus
2014-12-01
Full Text Available A new approach to design dual-band two-branch couplers with arbitrary coupling coefficients at two operating frequency bands is proposed in this article. The method is based on the usage of equivalent subcircuits input reactances of the even-mode and odd-mode excitations. The exact design formulas for three options of the dual-band coupler with different location and number of stubs are received. These formulas permit to obtain the different variants for each structure in order to select the physically realizable solution and can be used in broad range of frequency ratio and power division ratio. For verification, three different dual-band couplers, which are operating at 2.4/3.9 GHz with different coupling coefficients (one with 3/6 dB, and 10/3 dB two others are designed, simulated, fabricated and tested. The measured results are in good agreement with the simulated ones.
Waveguide silicon nitride grating coupler
Litvik, Jan; Dolnak, Ivan; Dado, Milan
2016-12-01
Grating couplers are one of the most used elements for coupling of light between optical fibers and photonic integrated components. Silicon-on-insulator platform provides strong confinement of light and allows high integration. In this work, using simulations we have designed a broadband silicon nitride surface grating coupler. The Fourier-eigenmode expansion and finite difference time domain methods are utilized in design optimization of grating coupler structure. The fully, single etch step grating coupler is based on a standard silicon-on-insulator wafer with 0.55 μm waveguide Si3N4 layer. The optimized structure at 1550 nm wavelength yields a peak coupling efficiency -2.6635 dB (54.16%) with a 1-dB bandwidth up to 80 nm. It is promising way for low-cost fabrication using complementary metal-oxide- semiconductor fabrication process.
Directory of Open Access Journals (Sweden)
Afshin Aslian
2016-01-01
Full Text Available Concentrated sunlight that is transmitted by fiber optics has been used for generating electricity, heat, and daylight. On the other hand, multijunction photovoltaic cells provide high efficiency for generating electricity from highly concentrated sunlight. This study deals with designing and simulating a high-efficiency coupler, employing a mathematical model to connect sunlight with fiber optics for multiple applications. The coupler concentrates and distributes irradiated light from a primary concentrator. In this study, a parabolic dish was used as the primary concentrator, a coupler that contains nine components called a compound truncated pyramid and a cone (CTPC, all of which were mounted on a plate. The material of both the CTPC and the plate was BK7 optical glass. Fiber optics cables and multijunction photovoltaic cells were connected to the cylindrical part of the CTPC. The fibers would transmit the light to the building to provide heat and daylight, whereas multijunction photovoltaic cells generate electricity. Theoretical and simulation results showed high performance of the designed coupler. The efficiency of the coupler was as high as 92%, whereas the rim angle of the dish increased to an optimum angle. Distributed sunlight in the coupler increased the flexibility and simplicity of the design, resulting in a system that provided concentrated electricity, heat, and lighting for residential buildings.
International Nuclear Information System (INIS)
Li, Y. M.; Liu, Kexin; Geng, Rongli
2014-01-01
Multipacting (MP) in higher-order-mode (HOM) couplers of the International Linear Collider (ILC) baseline cavity and the Continuous Electron Beam Accelerator Facility (CEBAF) 12 GeV upgrade cavity is studied by using the ACE3P suites, developed by the Advanced Computations Department at SLAC. For the ILC cavity HOM coupler, the simulation results show that resonant trajectories exist in three zones, corresponding to an accelerating gradient range of 0.6A-1.6 MV/m, 21A-34 MV/m, 32A-35 MV/m, and > 40MV/m, respectively. For the CEBAF 12 GeV upgrade cavity HOM coupler, resonant trajectories exist in one zone, corresponding to an accelerating gradient range of 6A-13 MV/m. Potential implications of these MP barriers are discussed in the context of future high energy pulsed as well as medium energy continuous wave (CW) accelerators based on superconducting radio frequency cavities. Frequency scaling of MPA's predicted in HOM couplers of the ILC, CBEAF upgrade, SNS and FLASH third harmonic cavity is given and found to be in good agreement with the analytical result based on the parallel plate model
Energy Technology Data Exchange (ETDEWEB)
Li, Y. M. [Peking University, Beijing (China); Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Liu, Kexin [Peking University, Beijing (China); Geng, Rongli [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
2014-02-01
Multipacting (MP) in higher-order-mode (HOM) couplers of the International Linear Collider (ILC) baseline cavity and the Continuous Electron Beam Accelerator Facility (CEBAF) 12 GeV upgrade cavity is studied by using the ACE3P suites, developed by the Advanced Computations Department at SLAC. For the ILC cavity HOM coupler, the simulation results show that resonant trajectories exist in three zones, corresponding to an accelerating gradient range of 0.6-1.6 MV/m, 21-34 MV/m, 32-35 MV/m, and > 40MV/m, respectively. For the CEBAF 12 GeV upgrade cavity HOM coupler, resonant trajectories exist in one zone, corresponding to an accelerating gradient range of 6-13 MV/m. Potential implications of these MP barriers are discussed in the context of future high energy pulsed as well as medium energy continuous wave (CW) accelerators based on superconducting radio frequency cavities. Frequency scaling of MP's predicted in HOM couplers of the ILC, CBEAF upgrade, SNS and FLASH third harmonic cavity is given and found to be in good agreement with the analytical result based on the parallel plate model.
Multipacting Simulations of Tuner-adjustable waveguide coupler (TaCo) with CST
Shafqat, Nuaman; Wegner, Rolf
2015-01-01
Tuner-adjustable waveguide couplers (TaCo) are used to feed microwave power to different RF structures of LINAC4. This paper studies the multipacting phenomenon for TaCo using PIC solver of CST PS. Simulations are performed for complete field sweeps and results are analysed.
Free electron laser variable bridge coupler
International Nuclear Information System (INIS)
Spalek, G.; Billen, J.H.; Garcia, J.A.; McMurry, D.E.; Harnsborough, L.D.; Giles, P.M.; Stevens, S.B.
1985-01-01
The Los Alamos free-electron laser (FEL) is being modified to test a scheme for recovering most of the power in the residual 20-MeV electron beam by decelerating the microbunches in a linear standing-wave accelerator and using the recovered energy to accelerate new beam. A variable-coupler low-power model that resonantly couples the accelerator and decelerator structures has been built and tested. By mixing the TE 101 and TE 102 modes, this device permits continuous variation of the decelerator fields relative to the accelerator fields through a range of 1:1 to 1:2.5. Phase differences between the two structures are kept below 1 0 and are independent of power-flow direction. The rf power is also fed to the two structures through this coupling device. Measurements were also made on a three-post-loaded variable coupler that is a promising candidate for the same task
RF front-end world class designs
Love, Janine
2009-01-01
All the design and development inspiration and direction a harware engineer needs in one blockbuster book! Janine Love site editor for RF Design Line,columnist, and author has selected the very best RF design material from the Newnes portfolio and has compiled it into this volume. The result is a book covering the gamut of RF front end design from antenna and filter design fundamentals to optimized layout techniques with a strong pragmatic emphasis. In addition to specific design techniques and practices, this book also discusses various approaches to solving RF front end design problems and h
An analysis of multislot directional coupler
International Nuclear Information System (INIS)
Arai, Hiroyuki; Goto, Naohisa; Yamamoto, Takumi.
1986-03-01
This paper presents an analysis of multislot directional coupler for monitoring the gyrotron output. We solved the boundary value problem of the directional coupler to investigate the detailed effect of finite thickness slot and mutual coupling between slots. Numerical data of coupler design is presented for non-resonant a pair slot, and mode sensitivity in overmoded waveguide is also evaluated. (author)
Chernoff, R. C.
1975-01-01
The described device can be used to measure the output of any dc powered RF source. No dummy load is required for the measurements. The device is, therefore, called the 'no-load calorimeter' (NLC). The NLC measures the power actually fed to the antenna or another useful load. It is believed that the NLC can compete successfully with directional coupler type systems in measuring the output of high-power RF sources.
Directory of Open Access Journals (Sweden)
Y. M. Li
2014-02-01
Full Text Available Multipacting (MP in higher-order-mode (HOM couplers of the International Linear Collider (ILC baseline cavity and the Continuous Electron Beam Accelerator Facility (CEBAF 12 GeV upgrade cavity is studied by using the ACE3P suites, developed by the Advanced Computations Department at SLAC. For the ILC cavity HOM coupler, the simulation results show that resonant trajectories exist in three zones, corresponding to an accelerating gradient range of 0.6–1.6 MV/m, 21–34 MV/m, 32–35 MV/m and >40 MV/m, respectively. For the CEBAF 12 GeV upgrade cavity HOM coupler, resonant trajectories exist in one zone, corresponding to an accelerating gradient range of 6–13 MV/m. Potential implications of these MP barriers are discussed in the context of future high-energy pulsed as well as medium-energy continuous wave accelerators based on superconducting radio frequency cavities. Frequency scaling of MP’s predicted in HOM couplers of the ILC, CEBAF upgrade, Spallation Neutron Source (SNS, and Free-Electron Laser in Hamburg (FLASH third harmonic cavity is given and found to be in good agreement with the analytical result based on the parallel plate model.
RF engineering basic concepts: S-parameters
Caspers, F
2011-01-01
The concept of describing RF circuits in terms of waves is discussed and the S-matrix and related matrices are defined. The signal flow graph (SFG) is introduced as a graphical means to visualize how waves propagate in an RF network. The properties of the most relevant passive RF devices (hybrids, couplers, non-reciprocal elements, etc.) are delineated and the corresponding S-parameters are given. For microwave integrated circuits (MICs) planar transmission lines such as the microstrip line have become very important.
High power tests of dressed supconducting 1.3 GHz RF cavities
Energy Technology Data Exchange (ETDEWEB)
Hocker, A.; Harms, E.R.; Lunin, A.; Sukhanov, A.; /Fermilab
2011-03-01
A single-cavity test cryostat is used to conduct pulsed high power RF tests of superconducting 1.3 GHz RF cavities at 2 K. The cavities under test are welded inside individual helium vessels and are outfitted ('dressed') with a fundamental power coupler, higher-order mode couplers, magnetic shielding, a blade tuner, and piezoelectric tuners. The cavity performance is evaluated in terms of accelerating gradient, unloaded quality factor, and field emission, and the functionality of the auxiliary components is verified. Test results from the first set of dressed cavities are presented here.
Design and characterization of dielectric-loaded plasmonic directional couplers
DEFF Research Database (Denmark)
Stær, Tobias Holmgaard; Chen, Zhuo; Bozhevolnyi, Sergey
2009-01-01
Ultracompact directional couplers (DCs) based on dielectric-loaded surface plasmon-polariton waveguides (DLSPPWs) are analyzed using the effective index method (EIM), with the coupling, both in the parallel interaction region and in- and out-coupling regions, being taken into account. Near-field...... characterization of fabricated DCs performed with a scanning near-field optical microscope verifies the applicability of the EIM in the analysis and design of DLSPPW-based wavelength-selective DCs. The design approach applicable to a large variety of integrated optical waveguides is developed, enabling...
Design of a high repetition rate S-band photocathode gun
International Nuclear Information System (INIS)
Han Janghui; Cox, Matthew; Huang, Houcheng; Pande, Shivaji
2011-01-01
Photocathode RF guns have been developed in many laboratories for generating high quality electron beams for free-electron lasers based on linear accelerators. Such guns can generate electron beams with an exceptionally high peak current as well as a small transverse emittance. Their applications have been recently expanded for ultrafast electron diffraction, coherent terahertz radiation, and X-ray or γ-ray radiation by Compton scattering. In this paper, we design an S-band normal-conducting gun with capabilities of high quality beam generation and high repetition rate operation. The RF design and thermal analysis of the gun cavity and coupler are introduced. Optimal position of the gun focusing solenoid for low emittance beam generation is found by performing particle tracking simulations. Then, the gun system is designed to be able to afford the optimal solenoid position. The cooling-water channel surrounding the gun cavity and coupler is designed and analyzed numerically. The pressure in the gun is simulated with a vacuum model containing the detailed inner structure of the gun. An injector for a free-electron laser application is designed by using this gun and the beam dynamics simulation is shown. A cold test with a prototype gun for confirmation of the RF design is reported. - Highlights: → We design an S-band gun for low emittance beam generation and high repetition rate operation. → The RF design and thermal analysis of the gun cavity and coupler are studied. → An FEL injector is designed by using this gun and the beam dynamics simulation is shown. → A cold test with a prototype gun for confirmation of the RF design is reported.
Silica-on-silicon optical couplers and coupler based optical filters
DEFF Research Database (Denmark)
Leick, Lasse
2002-01-01
is not an adequate description of the waveguides. A simple application for an optical couplers is as a 980/1550 nm mulitmplexer for erbium doped wavguide amplifiers. A numerical analysis shows that a directional coupler has acceptable specifications, whereas a mulit mode interference coupler does not. The wavelength......This work concerns modeling and chracterization of non ampligying silica-on-silicon optical components for wavelength division mulitplexed networks. Emphasis is placed on optical couplers and how they can be used as building blocks for devices with a larger complexity. It has been investigated how...... to construct wavelength flattened and process tolerant couplers. A thorough comparison between directional couplers, multi mode interference couplers and interferometer-based couplers has been performed. Numerically all these architectures have the ability to obtain similar wavelength-flatness, but the multi...
Directory of Open Access Journals (Sweden)
Weitong Chen
2016-11-01
Full Text Available This paper presents a cost-effectiveness comparison of coupler designs for wireless power transfer (WPT, meant for electric vehicle (EV dynamic charging. The design comparison of three common types of couplers is first based on the raw material cost, output power, transfer efficiency, tolerance of horizontal offset, and flux density. Then, the optimal cost-effectiveness combination is selected for EV dynamic charging. The corresponding performances of the proposed charging system are compared and analyzed by both simulation and experimentation. The results verify the validity of the proposed dynamic charging system for EVs.
Energy Technology Data Exchange (ETDEWEB)
Chen, Z. (Zukun)
2001-01-01
The Spallation Neutron Source (SNS) is an accelerator-based neutron scattering research facility. The linear accelerator (linac) is the principal accelerating structure and divided into a room-temperature linac and a superconducting linac. The normal conducting linac system that consists of a Drift Tube Linac (DTL) and a Coupled Cavity Linac (CCL) is to be built by Los Alamos National Laboratory. The CCL structure is 55.36-meters long. It accelerates H- beam from 86.8 Mev to 185.6 Mev at operating frequency of 805 MHz. This side coupled cavity structure has 8 cells per segment, 12 segments and 11 bridge couplers per module, and 4 modules total. A 5-MW klystron powers each module. The number 3 and number 9 bridge coupler of each module are connected to the 5-MW RF power supply. The bridge coupler with length of 2.5 {beta}{gamma} is a three-cell structure and located between the segments and allows power flow through the module. The center cell of each bridge coupler is excited during normal operation. To obtain a uniform electromagnetic filed and meet the resonant frequency shift, the RF induced heat must be removed. Thus, the thermal deformation and frequency shift studies are performed via numerical simulations in order to have an appropriate cooling design and predict the frequency shift under operation. The center cell of the bridge coupler also contains a large 4-inch slug tuner and a tuning post that used to provide bulk frequency adjustment and field intensity adjustment, so that produce the proper total field distribution in the module assembly.
Eighth CW and High Average Power RF Workshop
2014-01-01
We are pleased to announce the next Continuous Wave and High Average RF Power Workshop, CWRF2014, to take place at Hotel NH Trieste, Trieste, Italy from 13 to 16 May, 2014. This is the eighth in the CWRF workshop series and will be hosted by Elettra - Sincrotrone Trieste S.C.p.A. (www.elettra.eu). CWRF2014 will provide an opportunity for designers and users of CW and high average power RF systems to meet and interact in a convivial environment to share experiences and ideas on applications which utilize high-power klystrons, gridded tubes, combined solid-state architectures, high-voltage power supplies, high-voltage modulators, high-power combiners, circulators, cavities, power couplers and tuners. New ideas for high-power RF system upgrades and novel ways of RF power generation and distribution will also be discussed. CWRF2014 sessions will start on Tuesday morning and will conclude on Friday lunchtime. A visit to Elettra and FERMI will be organized during the workshop. ORGANIZING COMMITTEE (OC): Al...
Detuning related coupler kick variation of a superconducting nine-cell 1.3 GHz cavity
Hellert, Thorsten; Dohlus, Martin
2018-04-01
Superconducting TESLA-type cavities are widely used to accelerate electrons in long bunch trains, such as in high repetition rate free electron lasers. The TESLA cavity is equipped with two higher order mode couplers and a fundamental power coupler (FPC), which break the axial symmetry of the cavity. The passing electrons therefore experience axially asymmetrical coupler kicks, which depend on the transverse beam position at the couplers and the rf phase. The resulting emittance dilution has been studied in detail in the literature. However, the kick induced by the FPC depends explicitly on the ratio of the forward to the backward traveling waves at the coupler, which has received little attention. The intention of this paper is to present the concept of discrete coupler kicks with a novel approach of separating the field disturbances related to the standing wave and a reflection dependent part. Particular attention is directed to the role of the penetration depth of the FPC antenna, which determines the loaded quality factor of the cavity. The developed beam transport model is compared to dedicated experiments at FLASH and European XFEL. Both the observed transverse coupling and detuning related coupler kick variations are in good agreement with the model. Finally, the expected trajectory variations due to coupler kick variations at European XFEL are investigated and results of numerical studies are presented.
Alesini, D.; Di Pirro, G.; Di Raddo, R.; Ferrario, M.; Gallo, A.; Lollo, V.; Marcellini, F.; Higo, T.; Kakihara, K.; Matsumoto, S.; Campogiani, G.; Mostacci, A.; Palumbo, L.; Persichelli, S.; Spizzo, V.; Verdú-Andrés, S.
2011-01-01
The energy upgrade of the SPARC photo-injector from 160 to more than 260 MeV will be done by replacing a low gradient 3m S-Band structure with two 1.4m high gradient C-band structures. The structures are travelling wave, constant impedance sections, have symmetric waveguide input couplers and have been optimized to work with a SLED RF input pulse. A prototype with a reduced number of cells has been fabricated and tested at high power in KEK (Japan) giving very good performances in terms of breakdown rates (10^6 bpp/m) at high accelerating gradient (>50 MV/m). The paper illustrates the design criteria of the structures, the fabrication procedure and the high power RF test results.
Multipacting in a coaxial coupler with bias voltage for SRF operation with a large beam current
Liu, Z.-K.; Wang, Ch.; Chang, F.-Y.; Chang, L.-H.; Chang, M.-H.; Chen, L.-J.; Chung, F.-T.; Lin, M.-C.; Lo, C.-H.; Tsai, C.-L.; Tsai, M.-H.; Yeh, M.-S.; Yu, T.-C.
2016-09-01
A superconducting radio-frequency (SRF) module is commonly used for a high-energy accelerator; its purpose is to provide energy to the particle beam. Because of the low power dissipation and smaller impedance of a higher-order mode for this module, it can provide more power to the particle beam with better stability through decreasing the couple bunch instability. A RF coupler is necessary to transfer the high power from a RF generator to the cavity. A coupler of coaxial type is a common choice. With high-power operation, it might suffer from multipacting, which is a resonance phenomenon due to re-emission of secondary electrons. Applying a bias voltage between inner and outer conductors of the coaxial coupler might increase or decrease the strength of the multipacting effect. We studied the effect of a bias voltage on multipacting using numerical simulation to track the motion of the electrons. The simulation results and an application for SRF operation with a large beam current are presented in this paper.
Development of higher order mode couplers at Cornell
International Nuclear Information System (INIS)
Amato, J.C.
1988-01-01
Higher order mode (HOM) couplers are integral parts of a superconducting accelerator cavity. The damping which the couplers must provide is dictated by the frequency and shunt impedance of the cavity modes as well as by the stability requirements of the accelerator incorporating the cavities. Cornell's 5-cell 1500 MHz elliptical cavity was designed for use in a 50 x 50 GeV electron-positron storage ring with a total beam current of 3.5 mA (CESR-II). HOM couplers for the Cornell cavity were designed and evaluated with this machine in mind. The development of these couplers is described in this paper. 8 references, 8 figures
Design of electro-absorption modulator with tapered-mode coupler on the GeSi layer
International Nuclear Information System (INIS)
Li, Ym; Cheng, Bw
2013-01-01
A tapered-mode coupler integrated GeSi electro-absorption (EA) modulator is investigated theoretically. To improve the parameter insensitivity and modulation efficiency of the GeSi EA modulator based on evanescent coupling, a tapered coupler on the GeSi layer is introduced in our design. The two coupling mechanisms in our suggested structure are compared. Both the beam propagation method (BPM) calculation and coupling mode theory show almost 100% power transfer from the bottom rib waveguide to the GeSi layer. After a series of designs of the tapered coupler, we get a modulator with the advantages of both evanescent-coupling modulators (Feng et al 2011 Opt. Express 19 7062–7, Feng et al 2012 Opt. Express 20 22224–32, Liu et al 2008 Nature Photon. 2 433–7, Liu et al 2007 Opt. Express 15 623–8) and butt-coupling modulators (Lim et al 2011 Opt. Express 19 5040–6), that are ease of fabrication, low coupling loss, performance stability and high modulation efficiency. (paper)
International Nuclear Information System (INIS)
Wang, J.W.; Adolphsen, C.; Eichner, J.; Fuller, R.W.; Gold, S.L.; Hanna, S.M.; Hoag, H.A.; Holmes, S.G.; Koontz, R.F.; Lavine, Theodore L.; Loewen, R.J.; Miller, R.H.; Nantista, C.D.; Pope, R.; Rifkin, J.; Ruth, R.D.; Tantawi, S.G.; Vlieks, A.E.; Wilson, Z.; Yeremian, A.
2011-01-01
This paper describes an X-Band RF system for the Next Linear Collider Test Accelerator. The RF system consists of a 90 MeV injector and a 540 MeV linac. The main components of the injector are two low-Q single-cavity prebunchers and two 0.9-m-long detuned accelerator sections. The linac system consists of six 1.8-m-long detuned and damped detuned accelerator sections powered in pairs. The rf power generation, compression, delivery, distribution and measurement systems consist of klystrons, SLEDII energy compression systems, rectangular waveguides, magic-T's, and directional couplers. The phase and amplitude for each prebuncher is adjusted via a magic-T type phase shifter/attenuator. Correct phasing between the two 0.9 m accelerator sections is obtained by properly aligning the sections and adjusting two squeeze type phase shifters. Bunch phase and bunch length can be monitored with special microwave cavities and measurement systems. The design, fabrication, microwave measurement, calibration, and operation of the sub-systems and their components are briefly presented.
Wang, Qi Jie; Zhang, Ying; Soh, Yeng Chai
2005-12-01
This paper presents a novel lattice optical delay-line circuit using 3 × 3 directional couplers to implement three-port optical interleaving filters. It is shown that the proposed circuit can deliver three channels of 2pi/3 phase-shifted interleaving transmission spectra if the coupling ratios of the last two directional couplers are selected appropriately. The other performance requirements of an optical interleaver can be achieved by designing the remaining part of the lattice circuit. A recursive synthesis design algorithm is developed to calculate the design parameters of the lattice circuit that will yield the desired filter response. As illustrative examples, interleavers with maximally flat-top passband transmission and with given transmission performance on passband ripples and passband bandwidth, respectively, are designed to verify the effectiveness of the proposed design scheme.
The Design of Polymer Planar Optical Triplexer with MMI Filter and Directional Coupler
Directory of Open Access Journals (Sweden)
V. Jerabek
2013-12-01
Full Text Available Optical bidirectional WDM transceiver is a key component of the Passive Optical Network of the Fiber to the Home topology. Essential parts of such transceivers are filters that combine multiplexing and demultiplexing function of optical signal (triplexing filters. In this paper we report about a design of a new planar optical multi-wavelength selective system triplexing filter, which combines a multimode interference filter with directional coupler based on the epoxy polymer SU-8 on Si/SiO2 substrate. The optical triplexing filter was designed using the Beam Propagation Method. The aim of this project was to optimize the triplexing filter optical parameters and to minimize the planar optical wavelength selective system dimensions. The multimode interference filter was used for separation of downstream optical signal in designed optoelectronic integrated WDM transceiver. The directional coupler was used for adding of upstream optical signal.
High power coupler issues in normal conducting and superconducting accelerator applications
Energy Technology Data Exchange (ETDEWEB)
Matsumoto, H. [High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan)
2001-02-01
The ceramic material (Al{sub 2}O{sub 3}) commonly used for the klystron output coupler in normal conducting, and for an input coupler to superconducting cavities is one of the most troublesome parts in accelerator applications. But the performance can be improved very much by starting with high purity (>99.9%) alumina powder of controlled grain-size (0.1-0.5-{mu}m), and reducing the magnesium (Mg) sintering-binder to lower the dielectric loss to the order of 10{sup -4} at S-band frequencies. It has been confirmed that the new ceramic can stand a peak S-band frequency rf power of up to 300 MW and 2.5 {mu}sec pulse width. (author)
Circuit design for RF transceivers
Leenaerts, Domine; Vaucher, Cicero S
2007-01-01
Second edition of this successful 2001 RF Circuit Design book, has been updated, latest technology reviews have been added as well as several actual case studies. Due to the authors being active in industry as well as academia, this should prove to be an essential guide on RF Transceiver Design for students and engineers.
Superconducting Super Collider Laboratory coupled-cavity linac mechanical design
International Nuclear Information System (INIS)
Starling, W.J.; Cain, T.
1992-01-01
A collaboration between the Superconducting Super Collider Laboratory (SSCL) and the Los Alamos National Laboratory (LANL) for the engineering and mechanical design of the SSCL Coupled-Cavity Linac (CCL) has yielded an innovative example of the well known side coupled-cavity type of linear accelerator. The SSCL CCL accelerates an H - beam from 70 MeV to 600 MeV with an rf cavity structure consisting of eight tanks in each of nine modules for a total length of about 112 meters. Magnetically-coupled bridge couplers transfer power from tank to tank within a module. A single rf power input is located at the center bridge coupler of each module. The bridge couplers permit placement along the beam line of combined function focusing/steering electromagnets and diagnostic pods for beam instrumentation. Each tank and bridge coupler is rf frequency stabilized, nominally to 1,283 MHz, by water pumped through integral water passages. Air isolation grooves surround the water passages at each braze joint so that water-to-vacuum interfaces are avoided. Each tank is supported by adjustable spherical bearing rod end struts to permit alignment and accommodate thermal expansion and contraction of the rf structure. Tank struts, electromagnet/diagnostic pod support frames, vacuum manifolds and utilities are all mounted to a girder-and-leg support stand running the full length of the CCL. (Author) tab., fig
Cryogenic cooler thermal coupler
International Nuclear Information System (INIS)
Green, K.E.; Talbourdet, J.A.
1984-01-01
A thermal coupler assembly mounted to the coldfinger of a cryogenic cooler which provides improved thermal transfer between the coldfinger and the detector assembly mounted on the dewar endwell. The thermal coupler design comprises a stud and spring-loaded cap mounted on the coldfinger assembly. Thermal transfer is made primarily through the air space between the cap and coldwell walls along the radial surfaces. The cap is spring loaded to provide thermal contact between the cap and endwell end surfaces
Polarization converted coupler for plasma current drive experiments
International Nuclear Information System (INIS)
Arai, H.; Shimizu, S.; Goto, N.
1986-01-01
In this paper, the authors propose the polarization converted coupler which has narrow width shape and radiates electric field perpendicular to the main toroidal magnetic field. The advantages of the polarization converted coupler are as follows: (l) The rectangular waveguide as the transmission line has the high power capability. (2) The all metal design is not damaged by the fusion neutron. (3) The characteristic of this coupler is not changed widely, since the coupler has the matching section. For example, the VSWR of its input impedance is less than 2.0 for both water and air load. The authors present characteristics of the polarization converted coupler measured by the model experiments
HOM/LOM Coupler Study for the ILC Crab Cavity
International Nuclear Information System (INIS)
Xiao, L.; Li, Z.; Ko, K.
2007-01-01
The FNAL 9-cell 3.9GHz deflecting mode cavity designed for the CKM experiment was chosen as the baseline design for the ILC BDS crab cavity. The full 9-cell CKM cavity including the coupler end-groups was simulated using the parallel eigensolver Omega3P and scattering parameter solver S3P. It was found that both the notch filters for the HOM/LOM couplers are very sensitive to the notch gap, which is about 1.6MHz/micron and is more than 10 times more sensitive than the TTF cavity. It was also found in the simulation that the unwanted vertical π-mode (SOM) is strongly coupled to the horizontal 7π/9 mode which causes x-y coupling and reduces the effectiveness of the SOM damping. To meet the ILC requirements, the HOM/LOM couplers are redesigned to address these issues. With the new designs, the damping of the HOM/LOM modes is improved. The sensitivity of the notch filter for the HOM coupler is reduced by one order of magnitude. The notch filter for the LOM coupler is eliminated in the new design which significantly simplifies the geometry. In this paper, we will present the simulation results of the original CKM cavity and the progresses on the HOM/LOM coupler re-design and optimization
Optimized Ultrawideband and Uniplanar Minkowski Fractal Branch Line Coupler
Directory of Open Access Journals (Sweden)
Mohammad Jahanbakht
2012-01-01
Full Text Available The non-Euclidean Minkowski fractal geometry is used in design, optimization, and fabrication of an ultrawideband (UWB branch line coupler. Self-similarities of the fractal geometries make them act like an infinite length in a finite area. This property creates a smaller design with broader bandwidth. The designed 3 dB microstrip coupler has a single layer and uniplanar platform with quite easy fabrication process. This optimized 180° coupler also shows a perfect isolation and insertion loss over the UWB frequency range of 3.1–10.6 GHz.
RF emittance in a low energy electron linear accelerator
Sanaye Hajari, Sh.; Haghtalab, S.; Shaker, H.; Kelisani, M. Dayyani
2018-04-01
Transverse beam dynamics of an 8 MeV low current (10 mA) S-band traveling wave electron linear accelerator has been studied and optimized. The main issue is to limit the beam emittance, mainly induced by the transverse RF forces. The linac is being constructed at Institute for Research in Fundamental Science (IPM), Tehran Iran Labeled as Iran's First Linac, nearly all components of this accelerator are designed and constructed within the country. This paper discusses the RF coupler induced field asymmetry and the corresponding emittance at different focusing levels, introduces a detailed beam dynamics design of a solenoid focusing channel aiming to reduce the emittance growth and studies the solenoid misalignment tolerances. In addition it has been demonstrated that a prebuncher cavity with appropriate parameters can help improving the beam quality in the transverse plane.
Design and Calibration of an RF Actuator for Low-Level RF Systems
Geng, Zheqiao; Hong, Bo
2016-02-01
X-ray free electron laser (FEL) machines like the Linac Coherent Light Source (LCLS) at SLAC require high-quality electron beams to generate X-ray lasers for various experiments. Digital low-level RF (LLRF) systems are widely used to control the high-power RF klystrons to provide a highly stable RF field in accelerator structures for beam acceleration. Feedback and feedforward controllers are implemented in LLRF systems to stabilize or adjust the phase and amplitude of the RF field. To achieve the RF stability and the accuracy of the phase and amplitude adjustment, low-noise and highly linear RF actuators are required. Aiming for the upgrade of the S-band Linac at SLAC, an RF actuator is designed with an I/Qmodulator driven by two digital-to-analog converters (DAC) for the digital LLRF systems. A direct upconversion scheme is selected for RF actuation, and an on-line calibration algorithm is developed to compensate the RF reference leakage and the imbalance errors in the I/Q modulator, which may cause significant phase and amplitude actuation errors. This paper presents the requirements on the RF actuator, the design of the hardware, the calibration algorithm, and the implementation in firmware and software and the test results at LCLS.
International Nuclear Information System (INIS)
Puglisi, M.
1994-01-01
The design of a conventional RF system is always complex and must fit the needs of the particular machine for which it is planned. It follows that many different design criteria should be considered and analyzed, thus exceeding the narrow limits of a lecture. For this reason only the fundamental components of an RF system, including the generators, are considered in this short seminar. The most common formulas are simply presented in the text, while their derivations are shown in the appendices to facilitate, if desired, a more advanced level of understanding. (orig.)
Multipacting Simulations of Tuner-adjustable waveguide coupler (TaCo) with CST Particle Studio®
Shafqat, N; Wegner, R
2014-01-01
Tuner-adjustable waveguide couplers (TaCo) are used to feed microwave power to different RF structures of LINAC4. This paper studies the multipacting phenomenon for TaCo using the PIC solver of CST PS. Simulations are performed for complete field sweeps and results are analysed.
The RF Design of an HOM Polarized RF Gun for the ILC
International Nuclear Information System (INIS)
Wang, J.W.; Clendenin, J.E.; Colby, E.R.; Miller, R.A.; Lewellen, J.W.
2006-01-01
The ILC requires a polarized electron beam. While a highly polarized beam can be produced by a GaAs-type cathode in a DC gun of the type currently in use at SLAC, JLAB and elsewhere, the ILC injector system can be simplified and made more efficient if a GaAs-type cathode can be combined with a low emittance RF gun. Since this type of cathode is known to be extremely sensitive to vacuum contamination including back bombardment by electrons and ions, any successful polarized RF gun must have a significantly improved operating vacuum compared to existing RF guns. We present a new RF design for an L-Band normal conducting (NC) RF gun for the ILC polarized electron source. This design incorporates a higher order mode (HOM) structure, whose chief virtue in this application is an improved conductance for vacuum pumping on the cathode. Computer simulation models have been used to optimize the RF parameters with two principal goals: first to minimize the required RF power; second to reduce the peak surface field relative to the field at the cathode in order to suppress field emitted electron bombardment. The beam properties have been simulated initially using PARMELA. Vacuum and other practical issues for implementing this design are discussed
Directory of Open Access Journals (Sweden)
A M Poursaleh
2017-08-01
Full Text Available In this paper, the feasibility studty of a new method of RF power coupling to acceleration cavity of charged particles accelerator will be evaluated. In this method a slit is created around the accelerator cavity, and RF power amplifier modules is connected directly to the acceleration cavity. In fact, in this design, the cavity in addition to acting as an acceleration cavity, acts as a RF power combiner. The benefits of this method are avoiding the use of RF vacuum tubes, transmission lines, high power combiner and coupler. In this research, cylindrical and coaxial cavities were studied, and a small sample coaxial cavity is build by this method. The results of the resarch showed that compact, economical and safe RF accelerators can be achieved by the proposed method
Proceedings, CAS - CERN Accelerator School: RF for Accelerators, Ebeltoft, Denmark, 8 - 17 Jun 2010
Bailey, R
2012-01-01
These proceedings present the lectures given at the twenty-fourth specialized course organized by the CERN Accelerator School (CAS). The course was held in Ebeltoft, Denmark, from 8-17 June, 2010 in collaboration with Aarhus University, with the topic 'RF for Accelerators' While this topic has been covered by CAS previously, early in the 1990s and again in 2000, it was recognized that recent advances in the field warranted an updated course. Following introductory courses covering the background physics, the course attempted to cover all aspects of RF for accelerators; from RF power generation and transport, through cavity and coupler design, electronics and low level control, to beam diagnostics and RF gymnastics. The lectures were supplemented with several sessions of exercises, which were completed by discussion sessions on the solutions.
First cold test of TESLA superconducting RF cavity in horizontal cryostat (CHECHIA)
International Nuclear Information System (INIS)
Kuzminski, J.
1996-01-01
In the framework of the TESLA project, the horizontal cryostat (CHECHIA) was built to test a superconducting RF cavity equipped with its helium vessel, magnetic shielding, cold tuner, main coupler and higher order modes couplers under realistic conditions before final assembly of eight cavities into TESLA Test Facility cryo-module. The results of the first cold tests in CHECHIA, performed at DESY with a 9-cell cavity (C19) to be used in the TTF injector are presented. Additional measurements of mechanical stability under RF operation (frequency variation with He pressure, Lorentz detuning) and cryogenic and electric measurements of power dissipation are presented. (author)
Development of the RF cavity for the SKKUCY-9 compact cyclotron
International Nuclear Information System (INIS)
Shin, Seungwook; Lee, Jongchul; LEE, Byeong-No; Ha, Donghyup; Namgoong, Ho; Chai, Jongseo
2015-01-01
A 9 MeV compact cyclotron, named SKKUCY-9, for a radiopharmaceutical compound especially fludeoxyglucose (FDG) production for a positron emission tomography (PET) machine was developed at Sungkyunkwan University. H − ions which are produced from a Penning Ionization Gauge(PIG) ion source, travel through a normal conducting radio frequency (RF) cavity which operates at 83.2 MHz for an acceleration and electro-magnet for a beam focusing until the ions acquire energy of about 9 MeV. For installation at a small local hospital, our SKKUCY-9 cyclotron is developed to be compact and light-weight, comparable to conventional medical purpose cyclotrons. For compactness, we adapted a deep valley and large angle hill type for the electro-magnet design. Normally a RF cavity is installed inside of the empty space of the magnet valley region, which is extremely small in our case. We faced problems such as difficulties of installing the RF cavity, low Q-value. Despite of those difficulties, a compact RF cavity and its system including a RF power coupler to feed amplified RF power to the RF cavity and a fine tuner to compensate RF frequency variations was successfully developed and tested
Development of the RF cavity for the SKKUCY-9 compact cyclotron
Shin, Seungwook; Lee, Jongchul; LEE, Byeong-No; Ha, Donghyup; Namgoong, Ho; Chai, Jongseo
2015-09-01
A 9 MeV compact cyclotron, named SKKUCY-9, for a radiopharmaceutical compound especially fludeoxyglucose (FDG) production for a positron emission tomography (PET) machine was developed at Sungkyunkwan University. H- ions which are produced from a Penning Ionization Gauge(PIG) ion source, travel through a normal conducting radio frequency (RF) cavity which operates at 83.2 MHz for an acceleration and electro-magnet for a beam focusing until the ions acquire energy of about 9 MeV. For installation at a small local hospital, our SKKUCY-9 cyclotron is developed to be compact and light-weight, comparable to conventional medical purpose cyclotrons. For compactness, we adapted a deep valley and large angle hill type for the electro-magnet design. Normally a RF cavity is installed inside of the empty space of the magnet valley region, which is extremely small in our case. We faced problems such as difficulties of installing the RF cavity, low Q-value. Despite of those difficulties, a compact RF cavity and its system including a RF power coupler to feed amplified RF power to the RF cavity and a fine tuner to compensate RF frequency variations was successfully developed and tested.
Commissioning of the 400 MHz LHC RF System
Ciapala, Edmond; Baudrenghien, P; Brunner, O; Butterworth, A; Linnecar, T; Maesen, P; Molendijk, J; Montesinos, E; Valuch, D; Weierud, F
2008-01-01
The installation of the 400 MHz superconducting RF system in LHC is finished and commissioning is under way. The final RF system comprises four cryo-modules each with four cavities in the LHC tunnel straight section round IP4. Also underground in an adjacent cavern shielded from the main tunnel are the sixteen 300 kW klystron RF power sources with their high voltage bunkers, two Faraday cages containing RF feedback and beam control electronics, and racks containing all the slow controls. The system and the experience gained during commissioning will be described. In particular, results from conditioning the cavities and their movable main power couplers and the setting up of the low level RF feedbacks will be presented.
Substrate integrated waveguide (SIW 3 dB coupler for K-Band applications
Directory of Open Access Journals (Sweden)
Khalid Nurehansafwanah
2017-01-01
Full Text Available This paper presented a designed coupler by using Rogers RO4003C with thickness (h 0.508 mm and relative permittivity (εr 3.55. The four port network coupler operates in K-band (18-27 GHz and design by using substrate integrated waveguide (SIW method. The reflection coefficient and isolation coefficient of propose Substrate Integrated Waveguide (SIW coupler is below than -10 dB. Meanwhile the coupler requirements are phase shift 90° between coupled port and output. SIW are high performance broadband interconnects with excellent immunity to electromagnetic interference and suitable for use in microwave and communication electronics, as well as increase bandwidth systems. The designs of coupler are investigated using CST Microwave Studio simulation tool. This proposed couplers are varied from parameters that cover the frequency range (21 -24 GHz and better performance of scattering (S-parameter.
Quantum superchemistry in an output coupler of coherent matter waves
International Nuclear Information System (INIS)
Jing, H.; Cheng, J.
2006-01-01
We investigate the quantum superchemistry or Bose-enhanced atom-molecule conversions in a coherent output coupler of matter waves, as a simple generalization of the two-color photoassociation. The stimulated effects of molecular output step and atomic revivals are exhibited by steering the rf output couplings. The quantum noise-induced molecular damping occurs near a total conversion in a levitation trap. This suggests a feasible two-trap scheme to make a stable coherent molecular beam
Progress on the high-current 704 MHz superconducting RF cavity at BNL
International Nuclear Information System (INIS)
Xu, W.; Astefanous, C.; Belomestnykh, S.; Ben-Zvi, I.
2012-01-01
The 704 MHz high current superconducting cavity has been designed with consideration of both performance of fundamental mode and damping of higher order modes. A copper prototype cavity was fabricated by AES and delivered to BNL. RF measurements were carried out on this prototype cavity, including fundamental pass-band and HOM spectrum measurements, HOM studies using bead-pull setup, prototyping of antenna-type HOM couplers. The measurements show that the cavity has very good damping for the higher-order modes, which was one of the main goals for the high current cavity design. 3D cavity models were simulated with Omega3P code developed by SLAC to compare with the measurements. The paper describes the cavity design, RF measurement setups and results for the copper prototype. The progress with the niobium cavity fabrication will also be described.
Analysis of the rectangular resonator with butterfly MMI coupler using SOI
Kim, Sun-Ho; Park, Jun-Hee; Kim, Eudum; Jeon, Su-Jin; Kim, Ji-Hoon; Choi, Young-Wan
2018-02-01
We propose a rectangular resonator sensor structure with butterfly MMI coupler using SOI. It consists of the rectangular resonator, total internal reflection (TIR) mirror, and the butterfly MMI coupler. The rectangular resonator is expected to be used as bio and chemical sensors because of the advantages of using MMI coupler and the absence of bending loss unlike ring resonators. The butterfly MMI coupler can miniaturize the device compared to conventional MMI by using a linear butterfly shape instead of a square in the MMI part. The width, height, and slab height of the rib type waveguide are designed to be 1.5 μm, 1.5 μm, and 0.9 μm, respectively. This structure is designed as a single mode. When designing a TIR mirror, we considered the Goos-Hänchen shift and critical angle. We designed 3:1 MMI coupler because rectangular resonator has no bending loss. The width of MMI is designed to be 4.5 μm and we optimize the length of the butterfly MMI coupler using finite-difference time-domain (FDTD) method for higher Q-factor. It has the equal performance with conventional MMI even though the length is reduced by 1/3. As a result of the simulation, Qfactor of rectangular resonator can be obtained as 7381.
Beyond the Interconnections: Split Manufacturing in RF Designs
Directory of Open Access Journals (Sweden)
Yu Bi
2015-08-01
Full Text Available With the globalization of the integrated circuit (IC design flow of chip fabrication, intellectual property (IP piracy is becoming the main security threat. While most of the protection methods are dedicated for digital circuits, we are trying to protect radio-frequency (RF designs. For the first time, we applied the split manufacturing method in RF circuit protection. Three different implementation cases are introduced for security and design overhead tradeoffs, i.e., the removal of the top metal layer, the removal of the top two metal layers and the design obfuscation dedicated to RF circuits. We also developed a quantitative security evaluation method to measure the protection level of RF designs under split manufacturing. Finally, a simple Class AB power amplifier and a more sophisticated Class E power amplifier are used for the demonstration through which we prove that: (1 the removal of top metal layer or the top two metal layers can provide high-level protection for RF circuits with a lower request to domestic foundries; (2 the design obfuscation method provides the highest level of circuit protection, though at the cost of design overhead; and (3 split manufacturing may be more suitable for RF designs than for digital circuits, and it can effectively reduce IP piracy in untrusted off-shore foundries.
Design of a high power TM01 mode launcher optimized for manufacturing by milling
Energy Technology Data Exchange (ETDEWEB)
Dal Forno, Massimo [SLAC National Accelerator Lab., Menlo Park, CA (United States)
2016-12-15
Recent research on high-gradient rf acceleration found that hard metals, such as hard copper and hard copper-silver, have lower breakdown rate than soft metals. Traditional high-gradient accelerating structures are manufactured with parts joined by high-temperature brazing. The high temperature used in brazing makes the metal soft; therefore, this process cannot be used to manufacture structures out of hard metal alloys. In order to build the structure with hard metals, the components must be designed for joining without high-temperature brazing. One method is to build the accelerating structures out of two halves, and join them by using a low-temperature technique, at the symmetry plane along the beam axis. The structure has input and output rf power couplers. We use a TM01 mode launcher as a rf power coupler, which was introduced during the Next Linear Collider (NLC) work. The part of the mode launcher will be built in each half of the structure. This paper presents a novel geometry of a mode launcher, optimized for manufacturing by milling. The coupler was designed for the CERN CLIC working frequency f = 11.9942 GHz; the same geometry can be scaled to any other frequency.
Developmental efforts of RF collinear load for 10 MeV, 6 kW travelling wave Linac
International Nuclear Information System (INIS)
Kumar, Pankaj; Kumar, Harish; Soni, R.K.; Dwivedi, Jishnu; Thakurta, A.C.; Wanmode, Y.D.; Pareek, Prashant; Senthil Kumar, S; Shinde, R.S.
2015-01-01
RRCAT is developing a 10 MeV, 6 kW Travelling Wave Electron Linac for radiation processing applications. The remnant RF power from the Linac structure is taken out by output RF coupler and absorbed by the waveguide load. RF collinear load is an improved technique for absorption of the remnant RF power. It replaces the output RF coupler, RF window and waveguide load leading to reduction in size of magnetic elements and less transverse beam instabilities. In addition, it uses the remnant RF power to increase the electron beam energy. The collinear load consists of a number of copper cavities coated with microwave absorbing material at inner surfaces and brazed to the Linac structure at the end. Development of the collinear load has been started at RRCAT and a prototype low power collinear load using Kanthal (FeCrAl alloy) coating has been developed. Further works are going on the development of high power collinear load using FeSiAl alloy. The paper describes the development of the Kanthal based prototype low power collinear load as well as the works for the development of FeSiAl alloy based high power collinear load. (author)
He, Guobing; Gao, Yang; Xu, Yan; Ji, Lanting; Sun, Xiaoqiang; Wang, Xibin; Yi, Yunji; Chen, Changming; Wang, Fei; Zhang, Daming; Wu, Yuanda
2018-05-01
A polymer mode multiplexer based on asymmetric couplers is theoretically designed and experimentally demonstrated. The proposed X-junction coupler is formed by waveguides overlapped with different crossing angles in the vertical direction. A beam propagation method is adopted to optimize the dimensional parameters of the mode multiplexer to convert LP01 mode of two lower waveguides to LP11a and LP21a mode of the upper waveguide. The ultraviolet lithography and wet chemical etching are used in the fabrication process. A conversion ratio over 98% for both LP11a and LP21a mode in the wavelength range from 1530 to 1570 nm are experimentally demonstrated. This mode multiplexer has potential in broadband mode-division multiplexing transmission systems.
EM modeling of RF drive in DTL tank 4
International Nuclear Information System (INIS)
Kurennoy, Sergey S.
2012-01-01
A 3-D MicroWave Studio model for the RF drive in the LANSCE DTL tank 4 has been built. Both eigensolver and time-domain modeling are used to evaluate maximal fields in the drive module and RF coupling. The LANSCE DTL tank 4 has recently been experiencing RF problems, which may or may not be related to its replaced RF coupler. This situation stimulated a request by Dan Rees to provide EM modeling of the RF drive in the DTL tank 4 (T4). Jim O'Hara provided a CAD model that was imported into the CST Microwave Studio (MWS) and after some modifications became a part of a simplified MWS model of the T4 RF drive. This technical note describes the model and presents simulation results.
MAFIA simulation and cold model test of three types of bridge coupler
International Nuclear Information System (INIS)
Chang, C.R.; Yao, C.G.; Swenson, D.A.; Funk, L.W.; Raparia, D.
1992-01-01
In the new design of the SSC CCL, the total number of bridge couplers has increased from 50 to 63, and their maximum length increased from 37.2 to 46.1 cm. Choosing a bridge coupler that gives maximum coupling, minimum power flow, phase shift and fabrication cost becomes important. The conventional TM010 single cavity bridge coupler used in LAMPF and Fermilab will have severe mode mixing problem when the bridge length is over 30 cm, and the coupling is very weak. Three types of bridge coupler have been proposed: (1) TM012 single cavity bridge coupler; (2) electrically coupled multi-cavity bridge coupler and (3) magnetically coupled multi-cavity bridge coupler. This paper presents both MAFIA simulations and cold model tests results. Each bridge coupler has its unique characteristics with advantages and disadvantages, but all three are superior to the conventional coupler. (Author) 6 figs., tab., 2 refs
Coupler Development and Gap Field Analysis for the 352 MHz Superconducting CH-Cavity
Liebermann, H; Ratzinger, U; Sauer, A C
2004-01-01
The cross-bar H-type (CH) cavity is a multi-gap drift tube structure based on the H-210 mode currently under development at IAP Frankfurt and in collaboration with GSI. Numerical simulations and rf model measurements showed that the CH-type cavity is an excellent candidate to realize s.c. multi-cell structures ranging from the RFQ exit energy up to the injection energy into elliptical multi-cell cavities. The reasonable frequency range is from about 150 MHz up to 800 MHz. A 19-cell, β=0.1, 352 MHz, bulk niobium prototype cavity is under development at the ACCEL-Company, Bergisch-Gladbach. This paper will present detailed MicroWave Studio simulations and measurements for the coupler development of the 352 MHz superconducting CH cavity. It will describe possibilities for coupling into the superconducting CH-Cavity. The development of the coupler is supported by measurement on a room temperature CH-copper model. We will present the first results of the measurements of different couplers, e.g. capacitiv...
ACCELERATORS: RF system design and measurement of HIRF-CSRe
Xu, Zhe; Zhao, Hong-Wei; Wang, Chun-Xiao; Xia, Jia-Wen; Zhan, Wen-Long; Bian, Zhi-Bin
2009-05-01
An RF system for the CSRe (cooling storage experimental ring) is designed and manufactured domestically. The present paper mainly describes the RF system design in five main sections: ferrite ring, RF cavity, RF generator, low level system and cavity cooling. The cavity is based on a type of coaxial resonator which is shorted at the end with one gap and loaded with domestic ferrite rings. The RF generator is designed in the push-pull mode and the low level control system is based on a DSP+FGPA+DDS+USB interface and has three feedback loops. Finally we give the results of the measurement on our system.
First cold test of TESLA superconducting RF cavity in horizontal cryostat (CHECHIA)
International Nuclear Information System (INIS)
Kuzminski, J.
1996-01-01
In the framework of the TESLA project, the horizontal cryostat (CHECHIA) was built to test a superconducting RF cavity equipped with its helium vessel, magnetic shielding, cold tuner, main coupler and higher order modes couplers under realistic conditions before final assembly of eight cavities into TESLA Test Facility cryo-module. The results of the first cold tests in CHECHIA, performed at DESY with a 9-cell cavity (C19) to be used in the TTF injector are presented. (author)
International Nuclear Information System (INIS)
Ren Gang; Zheng Wanhua; Wang Ke; Du Xiaoyu; Xing Mingxin; Chen Lianghui
2008-01-01
In this paper a compact polarization beam splitter based on a deformed photonic crystal directional coupler is designed and simulated. The transverse-electric (TE) guided mode and transverse-magnetic (TM) guided mode are split due to different guiding mechanisms. The effect of the shape deformation of the air holes on the coupler is studied. It discovered that the coupling strength of the coupled waveguides is strongly enhanced by introducing elliptical airholes, which reduce the device length to less than 18.5μm. A finite-difference time-domain simulation is performed to evaluate the performance of the device, and the extinction ratios for both TE and TM polarized light are higher than 20 dB. (classical areas of phenomenology)
New window design options for CEBAF energy upgrade
International Nuclear Information System (INIS)
Phillips, L.; Mammosser, J.; Nguyen, V.
1997-01-01
As the Jefferson Laboratory upgrades the existing CEBAF electron accelerator to operate at higher energies, the fundamental power coupler windows will be required to operate with lower RF dissipation and increased immunity to radiation from cavity field emission. New designs and modifications to existing designs which can achieve these goals are described
A Third Generation Lower Hybrid Coupler
International Nuclear Information System (INIS)
Bernabei, S.; Hosea, J.; Kung, C.; Loesser, D.; Rushinski, J.; Wilson, J.R.; Parker, R.
2001-01-01
The Princeton Plasma Physics Laboratory (PPPL) and the Massachusetts Institute of Technology (MIT) are preparing an experiment of current profile control using lower-hybrid waves in order to produce and sustain advanced tokamak regimes in steady-state conditions in Alcator C-Mod. Unlike JET's, ToreSupra's and JT60's couplers, the C-Mod lower-hybrid coupler does not employ the now conventional multijunction design, but will have similar characteristics, compactness, and internal power division while retaining full control of the antenna element phasing. This is achieved by using 3 dB vertical power splitters and a stack of laminated plates with the waveguides milled in them. Construction is simplified and allows easy control and maintenance of all parts. Many precautions are taken to avoid arcing. Special care is also taken to avoid the recycling of reflected power which could affect the coupling and the launched n(subscript ||) spectrum. The results from C-Mod should allow further simplification in the designs of the coupler planned for KSTAR (Korea Superconducting Tokamak Advanced Research) and ITER (International Thermonuclear Experimental Reactor)
Transverse emittance dilution due to coupler kicks in linear accelerators
Directory of Open Access Journals (Sweden)
Brandon Buckley
2007-11-01
Full Text Available One of the main concerns in the design of low emittance linear accelerators (linacs is the preservation of beam emittance. Here we discuss one possible source of emittance dilution, the coupler kick, due to transverse electromagnetic fields in the accelerating cavities of the linac caused by the power coupler geometry. In addition to emittance growth, the coupler kick also produces orbit distortions. It is common wisdom that emittance growth from coupler kicks can be strongly reduced by using two couplers per cavity mounted opposite each other or by having the couplers of successive cavities alternate from above to below the beam pipe so as to cancel each individual kick. While this is correct, including two couplers per cavity or alternating the coupler location requires large technical changes and increased cost for superconducting cryomodules where cryogenic pipes are arranged parallel to a string of several cavities. We therefore analyze consequences of alternate coupler placements. We show here that alternating the coupler location from above to below compensates the emittance growth as well as the orbit distortions. For sufficiently large Q values, alternating the coupler location from before to after the cavity leads to a cancellation of the orbit distortion but not of the emittance growth, whereas alternating the coupler location from before and above to behind and below the cavity cancels the emittance growth but not the orbit distortion. We show that cancellations hold for sufficiently large Q values. These compensations hold even when each cavity is individually detuned, e.g., by microphonics. Another effective method for reducing coupler kicks that is studied is the optimization of the phase of the coupler kick so as to minimize the effects on emittance from each coupler. This technique is independent of the coupler geometry but relies on operating on crest. A final technique studied is symmetrization of the cavity geometry in the
RF Power Requirements for PEFP SRF Cavity Test
International Nuclear Information System (INIS)
Kim, Han Sung; Seol, Kyung Tae; Kwon, Hyeok Jung; Cho, Yong Sub
2011-01-01
For the future extension of the PEFP (Proton Engineering Frontier Project) Proton linac, preliminary study on the SRF (superconducting radio-frequency) cavity is going on including a five-cell prototype cavity development to confirm the design and fabrication procedures and to check the RF and mechanical properties of a low-beta elliptical cavity. The main parameters of the cavity are like followings. - Frequency: 700 MHz - Operating mode: TM010 pi mode - Cavity type: Elliptical - Geometrical beta: 0.42 - Number of cells: 5 - Accelerating gradient: 8 MV/m - Epeak/Eacc: 3.71 - Bpeak/Eacc: 7.47 mT/(MV/m) - R/Q: 102.3 ohm - Epeak: 29.68 MV/m (1.21 Kilp.) - Geometrical factor: 121.68 ohm - Cavity wall thickness: 4.3 mm - Stiffening structure: Double ring - Effective length: 0.45 m For the test of the cavity at low temperature of 4.2 K, many subsystems are required such as a cryogenic system, RF system, vacuum system and radiation shielding. RF power required to generate accelerating field inside cavity depends on the RF coupling parameters of the power coupler and quality factor of the SRF cavity and the quality factor itself is affected by several factors such as operating temperature, external magnetic field level and surface condition. Therefore, these factors should be considered to estimate the required RF power for the SRF cavity test
The TFTR RF Limiter upgrade design and installation
International Nuclear Information System (INIS)
Barnes, G.W.; Fan, H.M.; Ulrickson, M.
1991-01-01
The RF Limiters originally installed at Bays K-L and N-O[1] were upgraded to a new configuration and six new limiters of similar design were added. The RF Limiter upgrade protects the (2) existing RF Launchers and with a minor addition will protect the (2) RF Launchers to be installed in FY92 and will permit 50 Megawatts of auxiliary input power for two seconds during plasma operation. Each of the new RF Limiters are comprised of 18 tiles for a total of 108. The design provides for revised and strengthened supporting mounts because of additional forces induced in the tiles. Tile material is a 2D carbon-carbon composite identical to the original tile material. The channel shaped tile is geometrically the same as the original design. Subassembly of the panels took place outside the vessel in order to minimize exposure levels to the workers. Tooling was designed to replicate the vessel hardpoints and ease the subassembly tasks. Installation of the entire system occurred during the FY 91 opening. Integrated into the design are provisions to eliminate plasma damage to the insulators at the mounts. Detail design philosophy and an overview of the project are addressed by this paper. 2 refs., 2 figs
Zhao, W. N.; Yang, X. J.; Yao, C.; Ma, D. G.; Tang, H. J.
2017-10-01
Inductive power transfer (IPT) is a practical and preferable method for wireless electric vehicle (EV) charging which proved to be safe, convenient and reliable. Due to the air gap between the magnetic coupler, the magnetic field coupling decreases and the magnetic leakage increases significantly compared to traditional transformer, and this may lead to the magnetic flux density around the coupler more than the safety limit for human. So magnetic shielding should be adding to the winding made from litz wire to enhance the magnetic field coupling effect in the working area and reduce magnetic field strength in non-working area. Magnetic shielding can be achieved by adding high-permeability material or high-conductivity material. For high-permeability material its magnetic reluctance is much lower than the surrounding air medium so most of the magnetic line goes through the high-permeability material rather than surrounding air. For high-conductivity material the eddy current in the material can produce reverse magnetic field to achieve magnetic shielding. This paper studies the effect of the two types of shielding material on coupler for wireless EV charging and designs combination shielding made from high-permeability material and high-conductivity material. The investigation of the paper is done with the help of finite element analysis.
Refractive index engineering of high performance coupler for compact photonic integrated circuits
Liu, Lu; Zhou, Zhiping
2017-04-01
High performance couplers are highly desired in many applications, but the design is limited by nearly unchangeable material refractive index. To tackle this issue, refractive index engineering method is investigated, which can be realized by subwavelength grating. Subwavelength gratings are periodical structures with pitches small enough to locally synthesize the refractive index of photonic waveguides, which allows direct control of optical profile as well as easier fabrication process. This review provides an introduction to the basics of subwavelength structures and pay special attention to the design strategies of some representative examples of subwavelength grating devices, including: edge couplers, fiber-chip grating couplers, directional couplers and multimode interference couplers. Benefited from the subwavelength grating which can engineer the refractive index as well as birefringence and dispersion, these devices show better performance when compared to their conventional counterparts.
Theory, analysis and design of RF interferometric sensors
Nguyen, Cam
2012-01-01
Theory, Analysis and Design of RF Interferometric Sensors presents the theory, analysis and design of RF interferometric sensors. RF interferometric sensors are attractive for various sensing applications that require every fine resolution and accuracy as well as fast speed. The book also presents two millimeter-wave interferometric sensors realized using RF integrated circuits. The developed millimeter-wave homodyne sensor shows sub-millimeter resolution in the order of 0.05 mm without correction for the non-linear phase response of the sensor's quadrature mixer. The designed millimeter-wave double-channel homodyne sensor provides a resolution of only 0.01 mm, or 1/840th of the operating wavelength, and can inherently suppress the non-linearity of the sensor's quadrature mixer. The experimental results of displacement and velocity measurement are presented as a way to demonstrate the sensing ability of the RF interferometry and to illustrate its many possible applications in sensing. The book is succinct, ye...
Design of an L-band normally conducting RF gun cavity for high peak and average RF power
Energy Technology Data Exchange (ETDEWEB)
Paramonov, V., E-mail: paramono@inr.ru [Institute for Nuclear Research of Russian Academy of Sciences, 60-th October Anniversary prospect 7a, 117312 Moscow (Russian Federation); Philipp, S. [Deutsches Elektronen-Synchrotron DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Rybakov, I.; Skassyrskaya, A. [Institute for Nuclear Research of Russian Academy of Sciences, 60-th October Anniversary prospect 7a, 117312 Moscow (Russian Federation); Stephan, F. [Deutsches Elektronen-Synchrotron DESY, Platanenallee 6, D-15738 Zeuthen (Germany)
2017-05-11
To provide high quality electron bunches for linear accelerators used in free electron lasers and particle colliders, RF gun cavities operate with extreme electric fields, resulting in a high pulsed RF power. The main L-band superconducting linacs of such facilities also require a long RF pulse length, resulting in a high average dissipated RF power in the gun cavity. The newly developed cavity based on the proven advantages of the existing DESY RF gun cavities, underwent significant changes. The shape of the cells is optimized to reduce the maximal surface electric field and RF loss power. Furthermore, the cavity is equipped with an RF probe to measure the field amplitude and phase. The elaborated cooling circuit design results in a lower temperature rise on the cavity RF surface and permits higher dissipated RF power. The paper presents the main solutions and results of the cavity design.
Study on the coaxial couplers for disk and washer loaded accelerating structures
International Nuclear Information System (INIS)
Dajkovskij, A.G.; Paramonov, V.V.; Portugalov, Yu.I.; Ryabov, A.D.; Ryabova, T.D.
1983-01-01
The paper describes the dispersion and energy properties of the coaxial coupler (CC), which is a promising component for an accelerating system, with the disk and washer (DAW) structure. Resonators, consisting of the DAW structure sections and CC are shown to persist the main advantage of DAW structure, i.e. high stability of the accelerating field distribution. Therewith RF power losses are small. The presence of nonsymetriric modes in the neighbourbood of the operating mode is noted
Design of an X-band accelerating structure using a newly developed structural optimization procedure
Energy Technology Data Exchange (ETDEWEB)
Huang, Xiaoxia [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Fang, Wencheng; Gu, Qiang [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Zhao, Zhentang, E-mail: zhaozhentang@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)
2017-05-11
An X-band high gradient accelerating structure is a challenging technology for implementation in advanced electron linear accelerator facilities. The present work discusses the design of an X-band accelerating structure for dedicated application to a compact hard X-ray free electron laser facility at the Shanghai Institute of Applied Physics, and numerous design optimizations are conducted with consideration for radio frequency (RF) breakdown, RF efficiency, short-range wakefields, and dipole/quadrupole field modes, to ensure good beam quality and a high accelerating gradient. The designed X-band accelerating structure is a constant gradient structure with a 4π/5 operating mode and input and output dual-feed couplers in a racetrack shape. The design process employs a newly developed effective optimization procedure for optimization of the X-band accelerating structure. In addition, the specific design of couplers providing high beam quality by eliminating dipole field components and reducing quadrupole field components is discussed in detail.
Design and Development of RF Structures for Linac4
Vretenar, M; Gerigk, F; Pasini, M; Wegner, R
2006-01-01
Linac4 is a new 160 MeV Hâ linac proposed at CERN to replace the 50 MeV Linac2 as injector to the PS Booster, with the goal of doubling its brightness and intensity. The present design foresees after RFQ and chopping line a sequence of three accelerating structures: a Drift Tube Linac (DTL) from 3 to 40 MeV, a Cell-Coupled DTL (CCDTL) to 90 MeV and a Side Coupled Linac (SCL) up to the final energy. The DTL and CCDTL operate at 352 MHz, while in the SCL the frequency is doubled to 704 MHz. Although the injection in the PS Booster requires only a low duty cycle, the accelerating structures are designed to operate at the high duty cycle required by a possible future extension to a high-power linac driver for a neutrino facility. This paper presents the different accelerating structures, underlining the progress in the design of critical resonator elements, like post-couplers in the DTL, coupling slots in the CCDTL and bridge couplers for the SCL. Prototyping progress for the different structures is reported...
Broadband polymer microstructured THz fiber coupler with downdoped cores
DEFF Research Database (Denmark)
Nielsen, Kristian; Rasmussen, Henrik K.; Bang, Ole
2010-01-01
We demonstrate a broadband THz directional coupler based on a dual core photonic crystal fiber (PCF) design with mechanically down-doped core regions. For a center frequency of 1.3 THz we demonstrate a bandwidth of 0.65 THz.......We demonstrate a broadband THz directional coupler based on a dual core photonic crystal fiber (PCF) design with mechanically down-doped core regions. For a center frequency of 1.3 THz we demonstrate a bandwidth of 0.65 THz....
Wu, Yaw-Dong; Shih, Tien-Tsorng; Lee, Jian-Jang
2009-11-01
In this paper, we proposed the design of directional coupler integrated with ring resonator based on two-dimensional photonic crystals (2D PCs) to develop a triplexer filter. It can be widely used as the fiber access network element for multiplexer-demultiplexer wavelength selective in fiber-to-the-home (FTTH) communication systems. The directional coupler is chosen to separate the wavelengths of 1490nm and 1310nm. The ring resonator separates the wavelength of 1550nm. The transmission efficiency is larger than 90%. Besides, the total size of propose triplexer is only 19μm×12μm. We present simulation results using the finite-difference time-domain (FDTD) method for the proposed structure.
Large-Area Binary Blazed Grating Coupler between Nanophotonic Waveguide and LED
Directory of Open Access Journals (Sweden)
Hongqiang Li
2014-01-01
Full Text Available A large-area binary blazed grating coupler for the arrayed waveguide grating (AWG demodulation integrated microsystem on silicon-on-insulator (SOI was designed for the first time. Through the coupler, light can be coupled into the SOI waveguide from the InP-based C-band LED for the AWG demodulation integrated microsystem to function. Both the length and width of the grating coupler are 360 μm, as large as the InP-based C-band LED light emitting area in the system. The coupler was designed and optimized based on the finite difference time domain method. When the incident angle of the light source is 0°, the coupling efficiency of the binary blazed grating is 40.92%, and the 3 dB bandwidth is 72 nm at a wavelength of 1550 nm.
Design of a Ku band miniature multiple beam klystron
Energy Technology Data Exchange (ETDEWEB)
Bandyopadhyay, Ayan Kumar, E-mail: ayan.bandyopadhyay@gmail.com; Pal, Debasish; Kant, Deepender [Microwave Tubes Division, CSIR-CEERI, Pilani, Rajasthan-333031 (India); Saini, Anil; Saha, Sukalyan; Joshi, Lalit Mohan
2016-03-09
The design of a miniature multiple beam klystron (MBK) working in the Ku-band frequency range is presented in this article. Starting from the main design parameters, design of the electron gun, the input and output couplers and radio frequency section (RF-section) are presented. The design methodology using state of the art commercial electromagnetic design tools, analytical formulae as well as noncommercial design tools are briefly presented in this article.
LEDA RF distribution system design and component test results
International Nuclear Information System (INIS)
Roybal, W.T.; Rees, D.E.; Borchert, H.L.; McCarthy, M.; Toole, L.
1998-01-01
The 350 MHz and 700 MHz RF distribution systems for the Low Energy Demonstration Accelerator (LEDA) have been designed and are currently being installed at Los Alamos National Laboratory. Since 350 MHz is a familiar frequency used at other accelerator facilities, most of the major high-power components were available. The 700 MHz, 1.0 MW, CW RF delivery system designed for LEDA is a new development. Therefore, high-power circulators, waterloads, phase shifters, switches, and harmonic filters had to be designed and built for this applications. The final Accelerator Production of Tritium (APT) RF distribution systems design will be based on much of the same technology as the LEDA systems and will have many of the RF components tested for LEDA incorporated into the design. Low power and high-power tests performed on various components of these LEDA systems and their results are presented here
Fiber-chip edge coupler with large mode size for silicon photonic wire waveguides.
Papes, Martin; Cheben, Pavel; Benedikovic, Daniel; Schmid, Jens H; Pond, James; Halir, Robert; Ortega-Moñux, Alejandro; Wangüemert-Pérez, Gonzalo; Ye, Winnie N; Xu, Dan-Xia; Janz, Siegfried; Dado, Milan; Vašinek, Vladimír
2016-03-07
Fiber-chip edge couplers are extensively used in integrated optics for coupling of light between planar waveguide circuits and optical fibers. In this work, we report on a new fiber-chip edge coupler concept with large mode size for silicon photonic wire waveguides. The coupler allows direct coupling with conventional cleaved optical fibers with large mode size while circumventing the need for lensed fibers. The coupler is designed for 220 nm silicon-on-insulator (SOI) platform. It exhibits an overall coupling efficiency exceeding 90%, as independently confirmed by 3D Finite-Difference Time-Domain (FDTD) and fully vectorial 3D Eigenmode Expansion (EME) calculations. We present two specific coupler designs, namely for a high numerical aperture single mode optical fiber with 6 µm mode field diameter (MFD) and a standard SMF-28 fiber with 10.4 µm MFD. An important advantage of our coupler concept is the ability to expand the mode at the chip edge without leading to high substrate leakage losses through buried oxide (BOX), which in our design is set to 3 µm. This remarkable feature is achieved by implementing in the SiO 2 upper cladding thin high-index Si 3 N 4 layers. The Si 3 N 4 layers increase the effective refractive index of the upper cladding near the facet. The index is controlled along the taper by subwavelength refractive index engineering to facilitate adiabatic mode transformation to the silicon wire waveguide while the Si-wire waveguide is inversely tapered along the coupler. The mode overlap optimization at the chip facet is carried out with a full vectorial mode solver. The mode transformation along the coupler is studied using 3D-FDTD simulations and with fully-vectorial 3D-EME calculations. The couplers are optimized for operating with transverse electric (TE) polarization and the operating wavelength is centered at 1.55 µm.
Energy Technology Data Exchange (ETDEWEB)
Kim, Hae Jin, E-mail: haejin@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Wang, Son Jong; Park, Byoung Ho; Kwak, Jong-Gu [National Fusion Research Institute, Daejeon (Korea, Republic of); Hillairet, Julien [CEA/IRFM, Saint-lez-Durance (France); Choi, Jin Joo [Kwangwoon University, Seoul (Korea, Republic of)
2015-10-15
Highlights: • Amplitude balanced 3 dB coaxial hybrid splitter has been designed and rf tested. • The proposed hybrid is applicable to ITER ICRF transmission line for load resilience. • Two-section, broadband coaxial hybrid can be tunable by changing dielectric insulator. - Abstract: RF design and network analyzer tests of broadband, amplitude-balanced coaxial hybrid junctions are presented. We have designed two 3 dB hybrid splitters with 9 and 12 in. coaxial transmission lines applicable to ITER ICRF for load-resilient operations using ANSYS HFSS. Amplitude-balanced broadband responses were obtained with the combination of impedance reductions of longitudinal and transverse branches in unequal proportion, length change of 50 Ω lines and diameter change of high impedance lines connected transversely to the T-section of the hybrid splitter, respectively. We have fabricated and RF tested the 9 in. coaxial hybrid coupler. We obtained an excellent coupling flatness of −3.2 ± 0.2 dB, phase difference of 4 degrees and return loss of 16 dB in 40–55 MHz. The measured data of 9 in. hybrid splitter is highly consistent with HFSS simulations. We found that the proposed 3 dB hybrid splitter can be tunable with amplitude-balanced, broadband response by changing dielectric insulators to keep the inner and outer conductors of coaxial line apart. The proposed 3 dB hybrid splitter can be utilized for load-resilient operations in a wide range of antenna load variations due to mode transitions or edge localized modes (ELMs) in fusion plasmas.
International Nuclear Information System (INIS)
Kim, Hae Jin; Wang, Son Jong; Park, Byoung Ho; Kwak, Jong-Gu; Hillairet, Julien; Choi, Jin Joo
2015-01-01
Highlights: • Amplitude balanced 3 dB coaxial hybrid splitter has been designed and rf tested. • The proposed hybrid is applicable to ITER ICRF transmission line for load resilience. • Two-section, broadband coaxial hybrid can be tunable by changing dielectric insulator. - Abstract: RF design and network analyzer tests of broadband, amplitude-balanced coaxial hybrid junctions are presented. We have designed two 3 dB hybrid splitters with 9 and 12 in. coaxial transmission lines applicable to ITER ICRF for load-resilient operations using ANSYS HFSS. Amplitude-balanced broadband responses were obtained with the combination of impedance reductions of longitudinal and transverse branches in unequal proportion, length change of 50 Ω lines and diameter change of high impedance lines connected transversely to the T-section of the hybrid splitter, respectively. We have fabricated and RF tested the 9 in. coaxial hybrid coupler. We obtained an excellent coupling flatness of −3.2 ± 0.2 dB, phase difference of 4 degrees and return loss of 16 dB in 40–55 MHz. The measured data of 9 in. hybrid splitter is highly consistent with HFSS simulations. We found that the proposed 3 dB hybrid splitter can be tunable with amplitude-balanced, broadband response by changing dielectric insulators to keep the inner and outer conductors of coaxial line apart. The proposed 3 dB hybrid splitter can be utilized for load-resilient operations in a wide range of antenna load variations due to mode transitions or edge localized modes (ELMs) in fusion plasmas.
RF control at SSCL - an object oriented design approach
International Nuclear Information System (INIS)
Dohan, D.A.; Osberg, E.; Biggs, R.; Bossom, J.; Chillara, K.; Richter, R.; Wade, D.
1994-01-01
The Superconducting Super Collider (SSC) in Texas, the construction of which was stopped in 1994, would have represented a major challenge in accelerator research and development. This paper addresses the issues encountered in the parallel design and construction of the control systems for the RF equipment for the five accelerators comprising the SSC. An extensive analysis of the components of the RF control systems has been undertaken, based upon the Schlaer-Mellor object-oriented analysis and design (OOA/OOD) methodology. The RF subsystem components such as amplifiers, tubes, power supplies, PID loops, etc. were analyzed to produce OOA information, behavior and process models. Using these models, OOD was iteratively applied to develop a generic RF control system design. This paper describes the results of this analysis and the development of 'bridges' between the analysis objects, and the EPICS-based software and underlying VME-based hardware architectures. The application of this approach to several of the SSCL RF control systems is discussed. ((orig.))
Cahuantzi, Roberto; Buckley, Alastair
2017-09-01
Making accurate and reliable measurements of solar irradiance is important for understanding performance in the photovoltaic energy sector. In this paper, we present design details and performance of a number of fibre optic couplers for use in irradiance measurement systems employing remote light sensors applicable for either spectrally resolved or broadband measurement. The angular and spectral characteristics of different coupler designs are characterised and compared with existing state-of-the-art commercial technology. The new coupler designs are fabricated from polytetrafluorethylene (PTFE) rods and operate through forward scattering of incident sunlight on the front surfaces of the structure into an optic fibre located in a cavity to the rear of the structure. The PTFE couplers exhibit up to 4.8% variation in scattered transmission intensity between 425 nm and 700 nm and show minimal specular reflection, making the designs accurate and reliable over the visible region. Through careful geometric optimization near perfect cosine dependence on the angular response of the coupler can be achieved. The PTFE designs represent a significant improvement over the state of the art with less than 0.01% error compared with ideal cosine response for angles of incidence up to 50°.
Cahuantzi, Roberto; Buckley, Alastair
2017-09-01
Making accurate and reliable measurements of solar irradiance is important for understanding performance in the photovoltaic energy sector. In this paper, we present design details and performance of a number of fibre optic couplers for use in irradiance measurement systems employing remote light sensors applicable for either spectrally resolved or broadband measurement. The angular and spectral characteristics of different coupler designs are characterised and compared with existing state-of-the-art commercial technology. The new coupler designs are fabricated from polytetrafluorethylene (PTFE) rods and operate through forward scattering of incident sunlight on the front surfaces of the structure into an optic fibre located in a cavity to the rear of the structure. The PTFE couplers exhibit up to 4.8% variation in scattered transmission intensity between 425 nm and 700 nm and show minimal specular reflection, making the designs accurate and reliable over the visible region. Through careful geometric optimization near perfect cosine dependence on the angular response of the coupler can be achieved. The PTFE designs represent a significant improvement over the state of the art with less than 0.01% error compared with ideal cosine response for angles of incidence up to 50°.
RF control studies for moderate beamtime coupling between SRF cavities
International Nuclear Information System (INIS)
Doolittle, L.R.; Wang, D.X.
1998-01-01
When an SRF accelerator is designed, there is motivation to move the cavities close together on the beamline. Assuming the beamline apertures are not shrunk as well, this compaction (which will increase the overall accelerating gradient and/or lower the dynamic cryogenic heat load) increases the inter-cavity coupling. Within certain limits, the control system can compensate for this coupling by retuning each of the cavities. This paper describes constraints on the RF system, tuners, couplers, and control systems that are required to provide stable operation of cavities in the presence of inter-cavity coupling that exceeds the loaded bandwidth of an individual cavity
Design of 250-MW CW RF system for APT
International Nuclear Information System (INIS)
Rees, D.
1997-01-01
The design for the RF systems for the APT (Accelerator Production of Tritium) proton linac will be presented. The linac produces a continuous beam power of 130 MW at 1300 MeV with the installed capability to produce up to a 170 MW beam at 1700 MeV. The linac is comprised of a 350 MHz RFQ to 7 MeV followed in sequence by a 700 MHz coupled-cavity drift tube linac, coupled-cavity linac, and superconducting (SC) linac to 1700 MeV. At the 1700 MeV, 100 mA level the linac requires 213 MW of continuous-wave (CW) RF power. This power will be supplied by klystrons with a nominal output power of 1.0 MW. 237 kystrons are required with all but three of these klystrons operating at 700 MHz. The klystron count includes redundancy provisions that will be described which allow the RF systems to meet an operational availability in excess of 95 percent. The approach to achieve this redundancy will be presented for both the normal conducting (NC) and SC accelerators. Because of the large amount of CW RF power required for the APT linac, efficiency is very important to minimize operating cost. Operation and the RF system design, including in-progress advanced technology developments which improve efficiency, will be discussed. RF system performance will also be predicted. Because of the simultaneous pressures to increase RF system reliability, reduce tunnel envelope, and minimize RF system cost, the design of the RF vacuum windows has become an important issue. The power from a klystron will be divided into four equal parts to minimize the stress on the RF vacuum windows. Even with this reduction, the RF power level at the window is at the upper boundary of the power levels employed at other CW accelerator facilities. The design of a 350 MHz, coaxial vacuum window will be presented as well as test results and high power conditioning profiles. The transmission of 950 kW, CW, power through this window has been demonstrated with only minimal high power conditioning
Autopsy on an RF-Processed X-band Travelling Wave Structure
International Nuclear Information System (INIS)
Le Pimpec, Frederic
2002-01-01
In an effort to locate the cause(s) of high electric-field breakdown in x-band accelerating structures, we have cleanly-autopsied (no debris added by post-operation structure disassembly) an RF-processed structure. Macroscopic localization provided operationally by RF reflected wave analysis and acoustic sensor pickup was used to connect breakdowns to autopsied crater damage areas. Surprisingly, the microscopic analyses showed breakdown craters in areas of low electric field. High currents induced by the magnetic field on sharp corners of the input coupler appears responsible for the extreme breakdown damage observed
Design and Measurements of an X-Band Accelerating Cavity for SPARC
Alesini, David; Falone, Antonio; Ferrario, Massimo; Migliorati, Mauro; Mostacci, Andrea; Palpini, Federica; Palumbo, Luigi; Spataro, Bruno
2005-01-01
The paper presents the design of an X-band accelerating section for linearizing the longitudinal phase space in the Frascati Linac Coherent Light Source (SPARC). The structure, operating on the pi standing wave mode, is a 9 cells structure feeded by a central waveguide coupler and has been designed to obtain a 5 MV accelerating voltage. The 2D profile has been obtained using the e.m. codes SUPERFISH and OSCARD2D while the coupler has been designed using HFSS. Bead-pull measurement made on a copper prototype are illustrated and compared with the numerical results. Mechanical details of the realized prototype and RF properties of the structure as a function of the assembly characteristics are also discussed.
DESIGN OF A DC/RF PHOTOELECTRON GUN
International Nuclear Information System (INIS)
YU, D.; NEWSHAM, Y.; SMIRONOV, A.; YU, J.; SMEDLEY, J.; SRINIVASAN RAU, T.; LEWELLEN, J.; ZHOLENTS, A.
2003-01-01
An integrated dc/rf photoelectron gun produces a low-emittance beam by first rapidly accelerating electrons at a high gradient during a short (∼1 ns), high-voltage pulse, and then injecting the electrons into an rf cavity for subsequent acceleration. Simulations show that significant improvement of the emittance appears when a high field (∼ 0.5-1 GV/m) is applied to the cathode surface. An adjustable dc gap ((le) 1 mm) which can be integrated with an rf cavity is designed for initial testing at the Injector Test Stand at Argonne National Laboratory using an existing 70-kV pulse generator. Plans for additional experiments of an integrated dc/rf gun with a 250-kV pulse generator are being made
Structural Analysis of Taper-Threaded Rebar Couplers
International Nuclear Information System (INIS)
Chu, Seok Jae; Kwon, Hyuk Mo; Seo, Sang Hwan
2014-01-01
A number of rebar couplers were developed by the leading companies. The information about the products is available from the company website. However, the theory on the taper-threaded coupler is not available. In this paper, the mechanics of the taper-thread was developed to understand the effect of the tightening torque. Structural analysis of our own newly developed rebar coupler was done to improve the strength of the coupler. The taper-threaded rebar coupler was analyzed. The tightening of the rebar into the coupler developed a circumferential stress in the coupler. The circumferential stress depends on the coefficient of friction as well as the tightening torque. The circumferential stress is less than the allowable stress 20 kgf/mm 2 of the material for the coefficient of friction greater than 0.1. The tightening of the rebar into the coupler and the subsequent tensioning was simulated using CATIA. Linear elastic analysis considering contact was done. The tightening of the taper-threaded rebar developed a uniform stress distribution in both standard coupler and position coupler. On the other hand, the tightening of the nut in the axial direction developed a non-uniform stress distribution. Similarly the tensioning also developed a non-uniform stress distribution
A coupler for parasitic mode diagnosis in an X-band triaxial klystron amplifier
Directory of Open Access Journals (Sweden)
Wei Zhang
2017-10-01
Full Text Available The traditional methods of parasitic mode excitation diagnosis in an X-band triaxial klystron amplifier (TKA meet two difficulties: limited installation space and vacuum sealing. In order to solve these issues, a simple and compact coupler with good sealing performance, which can prevent air flow between the main and the auxiliary waveguides, is proposed and investigated experimentally. The coupler is designed with the aperture diffraction theory and the finite-different time-domain (FDTD method. The designed coupler consists of a main coaxial waveguide (for microwave transmission and a rectangular auxiliary waveguide (for parasitic mode diagnosis. The entire coupler structure has been fabricated by macromolecule polymer which is transparent to microwave signal in frequency range of X-band. The metal coating of about 200 microns has been performed through electroplating technique to ensure that the device operates well at high power. A small aperture is made in the metal coating. Hence, microwave can couple through the hole and the wave-transparent medium, whereas air flow is blocked by the wave-transparent medium. The coupling coefficient is analyzed and simulated with CST software. The coupler model is also included in particle-in-cell (PIC simulation with CHIPIC software and the associated parasitic mode excitation is studied. A frequency component of 11.46 GHz is observed in the FFT of the electric field of the drift tube and its corresponding competition mode appears as TE61 mode according to the electric field distribution. Besides, a frequency component of 10.8 GHz is also observed in the FFT of the electric field. After optimization of TE61 mode suppression, an experiment of the TKA with the designed coupler is carried out and the parasitic mode excitation at 10.8 GHz is observed through the designed coupler.
Computational Tools for RF Structure Design
Jensen, E
2004-01-01
The Finite Differences Method and the Finite Element Method are the two principally employed numerical methods in modern RF field simulation programs. The basic ideas behind these methods are explained, with regard to available simulation programs. We then go through a list of characteristic parameters of RF structures, explaining how they can be calculated using these tools. With the help of these parameters, we introduce the frequency-domain and the time-domain calculations, leading to impedances and wake-fields, respectively. Subsequently, we present some readily available computer programs, which are in use for RF structure design, stressing their distinctive features and limitations. One final example benchmarks the precision of different codes for calculating the eigenfrequency and Q of a simple cavity resonator.
B factory RF system design issues
International Nuclear Information System (INIS)
Zisman, M.S.
1992-01-01
We discuss the issues of relevance to the design of a B factory RF system. First, the general parameter regime is outlined, and the reasons behind certain commonly made choices are indicated. This regime involves high beam currents, and many relatively short bunches. Next, the physics difficulties associated with coupled-bunch instabilities are described briefly. We then describe in general terms the alternative approaches taken by various B factory designers, the motivation for these choices, and the technical issues raised by them. Technical solutions have been proposed for both the room-temperature and the superconducting RF scenarios, and considerable R ampersand D is being carried out worldwide to confirm and optimize these solutions
B factory rf system design issues
International Nuclear Information System (INIS)
Zisman, M.S.
1992-06-01
We discuss the issues of relevance to the design of a B factory RF system. First, the general parameter regime is outlined, and the reasons behind certain commonly made choices are indicated. This regime involves high beam currents, and many relatively short bunches. Next, the physics difficulties associated with coupled-bunch instabilities are described briefly. We then describe in general terms the alternative approaches taken by various B factory designers, the motivation for these choices, and the technical issues raised by them. Technical solutions have been proposed for both the room-temperature and the superconducting RF scenarios, and considerable R ampersand D is being carried out worldwide to confirm and optimize these solutions
Coupler for nuclear reactor absorber rods
International Nuclear Information System (INIS)
Kerz, K.
1984-01-01
A coupler is described for absorber rods being suspended during operation of nuclear reactors which includes plurality of actuating elements being movable for individually and jointly releasing the coupler, the movement of each of the actuating elements for releasing the coupler being independently controllable
Fundamental mode rf power dissipated in a waveguide attached to an accelerating cavity
International Nuclear Information System (INIS)
Kang, Y.W.
1993-01-01
An accelerating RF cavity usually requires accessory devices such as a tuner, a coupler, and a damper to perform properly. Since a device is attached to the wall of the cavity to have certain electrical coupling of the cavity field through the opening. RF power dissipation is involved. In a high power accelerating cavity, the RF power coupled and dissipated in the opening and in the device must be estimated to design a proper cooling system for the device. The single cell cavities of the APS storage ring will use the same accessories. These cavities are rotationally symmetric and the fields around the equator can be approximated with the fields of the cylindrical pillbox cavity. In the following, the coupled and dissipated fundamental mode RF power in a waveguide attached to a pillbox cavity is discussed. The waveguide configurations are (1) aperture-coupled cylindrical waveguide with matched load termination; (2) short-circuited cylindrical waveguide; and (3) E-probe or H-loop coupled coaxial waveguide. A short-circuited, one-wavelength coaxial structure is considered for the fundamental frequency rejection circuit of an H-loop damper
Fabrication of LD-3 Polymer Directional Couplers
National Research Council Canada - National Science Library
Chen, Ray T
1998-01-01
.... LD-3 polymer directional couplers arc designed and fabricated to operate at 1.3 microns. Waveguide propagation losses, device characterization, demonstration of cross coupling and packaged device pictures are presented in this final report.
RF-Frontend Design for Process-Variation-Tolerant Receivers
Sakian, Pooyan; van Roermund, Arthur
2012-01-01
This book discusses a number of challenges faced by designers of wireless receivers, given complications caused by the shrinking of electronic and mobile devices circuitry into ever-smaller sizes and the resulting complications on the manufacturability, production yield, and the end price of the products. The authors describe the impact of process technology on the performance of the end product and equip RF designers with countermeasures to cope with such problems. The mechanisms by which these problems arise are analyzed in detail and novel solutions are provided, including design guidelines for receivers with robustness to process variations and details of circuit blocks that obtain the required performance level. Describes RF receiver frontends and their building blocks from a system- and circuit-level perspective; Provides system-level analysis of a generic RF receiver frontend with robustness to process variations; Includes details of CMOS circuit design at 60GHz and reconfigurable circuits at 60GHz...
High Power RF Test Facility at the SNS
Kang, Yoon W; Campisi, Isidoro E; Champion, Mark; Crofford, Mark; Davis, Kirk; Drury, Michael A; Fuja, Ray E; Gurd, Pamela; Kasemir, Kay-Uwe; McCarthy, Michael P; Powers, Tom; Shajedul Hasan, S M; Stirbet, Mircea; Stout, Daniel; Tang, Johnny Y; Vassioutchenko, Alexandre V; Wezensky, Mark
2005-01-01
RF Test Facility has been completed in the SNS project at ORNL to support test and conditioning operation of RF subsystems and components. The system consists of two transmitters for two klystrons powered by a common high voltage pulsed converter modulator that can provide power to two independent RF systems. The waveguides are configured with WR2100 and WR1150 sizes for presently used frequencies: 402.5 MHz and 805 MHz. Both 402.5 MHz and 805 MHz systems have circulator protected klystrons that can be powered by the modulator capable of delivering 11 MW peak and 1 MW average power. The facility has been equipped with computer control for various RF processing and complete dual frequency operation. More than forty 805 MHz fundamental power couplers for the SNS superconducting linac (SCL) cavitites have been RF conditioned in this facility. The facility provides more than 1000 ft2 floor area for various test setups. The facility also has a shielded cave area that can support high power tests of normal conducti...
RF MEMS theory, design, and technology
Rebeiz, Gabriel M
2003-01-01
Ultrasmall Radio Frequency and Micro-wave Microelectromechanical systems (RF MEMs), such as switches, varactors, and phase shifters, exhibit nearly zero power consumption or loss. For this reason, they are being developed intensively by corporations worldwide for use in telecommunications equipment. This book acquaints readers with the basics of RF MEMs and describes how to design practical circuits and devices with them. The author, an acknowledged expert in the field, presents a range of real-world applications and shares many valuable tricks of the trade.
A 201-MHz Normal Conducting RF Cavity for the International MICE Experiment
International Nuclear Information System (INIS)
Li, D.; DeMello, A.J.; Virostek, Steve; Zisman, Michael S.; Rimmer, Robert
2008-01-01
MICE is a demonstration experiment for the ionization cooling of muon beams. Eight RF cavities are proposed to be used in the MICE cooling channel. These cavities will be operated in a strong magnetic field; therefore, they must be normal conducting. The cavity design and construction are based on the successful experience and techniques developed for a 201-MHz prototype cavity for the US MUCOOL program. Taking advantage of a muon beamΛ s penetration property, the cavity employs a pair of curved thin beryllium windows to terminate conventional beam irises and achieve higher cavity shunt impedance. The cavity resembles a round, closed pillbox cavity. Two half-shells spun from copper sheets are joined by e-beam welding to form the cavity body. There are four ports on the cavity equator for RF couplers, vacuum pumping and field probes. The ports are formed by means of an extruding technique.
Ultrahigh-efficiency apodized grating coupler using fully etched photonic crystals
DEFF Research Database (Denmark)
Ding, Yunhong; Ou, Haiyan; Peucheret, Christophe
2013-01-01
We present an efficient method to design apodized grating couplers with Gaussian output profiles for efficient coupling between standard single mode fibers and silicon chips. An apodized grating coupler using fully etched photonic crystal holes on the silicon-on-insulator platform is designed......, and fabricated in a single step of lithography and etching. An ultralow coupling loss of x2212;1.74x2009;x2009;dB (67% coupling efficiency) with a 3xA0;dB bandwidth of 60xA0;nm is experimentally measured....
A Tandem Coupler for Terahertz Integrated Circuits
Reck, Theodore J.; Deal, William; Chattopadhyay, Goutam
2013-01-01
A coplanar waveguide 3 dB quadrature coupler operating from 500 to 700 GHz is designed, fabricated and measured. On-wafer measurements demonstrate an amplitude balance of +/-2 dB and phase balance of +/-20 deg.
AnalogRF and mixed-signal circuit systematic design
Tlelo-Cuautle, Esteban; Castro-Lopez, Rafael
2013-01-01
Despite the fact that in the digital domain, designers can take full benefits of IPs and design automation tools to synthesize and design very complex systems, the analog designers’ task is still considered as a ‘handcraft’, cumbersome and very time consuming process. Thus, tremendous efforts are being deployed to develop new design methodologies in the analog/RF and mixed-signal domains. This book collects 16 state-of-the-art contributions devoted to the topic of systematic design of analog, RF and mixed signal circuits. Divided in the two parts Methodologies and Techniques recent theories, synthesis techniques and design methodologies, as well as new sizing approaches in the field of robust analog and mixed signal design automation are presented for researchers and R/D engineers.
RF cavity R and D at LBNL for the NLC damping rings, FY1999
International Nuclear Information System (INIS)
Rimmer, R.A.; Corlett, J.N.; Koehler, G.; Li, D.; Hartman, N.; Rasson, J.; Saleh, T.
1999-01-01
This report contains a summary of the R and D activities at LBNL on RF cavities for the NLC damping rings during fiscal year19999. These activities include the optimization of the RF design for both efficiency and damping of higher-order (HOMs), by systematic study of the cavity profile, the effect of the beam pipe diameter, nosecone angle and gap, the cross section and position of the HOM damping waveguides and the coupler. The effect of the shape of the HOM waveguides and their intersection with the cavity wall on the local surface heating is also an important factor, since it determines the highest stresses in the cavity body. This was taken into account during the optimization so that the stresses could be reduced at the same time as the HOP damping was improved over previous designs. A new method of calculating the RF heating was employed, using a recently released high frequency electromagnetic element in ANSYS. This greatly facilitates the thermal and stress analysis of the design and fabrication methods have been developed with the goals of lower stresses, fewer parts and simpler assembly compared to previous designs. This should result in substantial cost savings. Preliminary designs are described for the cavity ancillary components including the RF window, HOM loads, and tuners. A preliminary manufacturing plan is included, with an initial estimate of the resource requirements. Other cavity options are discussed which might be desirable to either lower the R/Q, for reduced transient response, or lower the residual HOM impedance to reduce coupled-bunch growth rates further still
Introduction to RF power amplifier design and simulation
Eroglu, Abdullah
2015-01-01
Introduction to RF Power Amplifier Design and Simulation fills a gap in the existing literature by providing step-by-step guidance for the design of radio frequency (RF) power amplifiers, from analytical formulation to simulation, implementation, and measurement. Featuring numerous illustrations and examples of real-world engineering applications, this book:Gives an overview of intermodulation and elaborates on the difference between linear and nonlinear amplifiersDescribes the high-frequency model and transient characteristics of metal-oxide-semiconductor field-effect transistorsDetails activ
Cavity design and beam simulations for the APS rf gun
International Nuclear Information System (INIS)
Borland, M.
1991-01-01
An earlier note discussed the preliminary design of the 1-1/2 cell RF cavity for the APS RF gun. This note describes the final design, including cavity properties and simulation results from the program rf gun. The basic idea for the new design was that the successful SSRL design could be improved upon by reducing fields that had nonlinear dependence on radius. As discussed previously, this would reduce the emittance and produce tighter momentum and time distributions. In addition, it was desirable to increase the fields in the first half-cell relative to the fields in the second half-cell, in order to allow more rapid initial acceleration, which would reduce the effects of space charge. Both of these goals were accomplished in the new design
Study of Arc-Related RF Faults in the CEBAF Cryomodules
Energy Technology Data Exchange (ETDEWEB)
Douglas Curry; Ganapati Myneni; Ganapati Rao Myneni; John Musson; Thomas Powers; Timothy Whitlatch; Isidoro Campisi; Haipeng Wang
2004-07-01
A series of measurements has been conducted on two superconducting radio-frequency (RF) cavity pairs, installed in cryomodules and routinely operated in the Continuous Electron Beam Accelerator Facility, in order to study the RF-vacuum interaction during an RF fault. These arc-related fault rates increase with increasing machine energy, contribute to system downtime, and directly affect the accelerator's availability. For this study, the fundamental power coupler waveguides have been instrumented with vacuum gauges, additional arc detectors, additional infrared sensors, and temperature sensors in order to measure the system response during both steady-state operations and RF fault conditions. Residual gas analyzers have been installed on the waveguide vacuum manifolds to monitor the gas species present during cooldown, RF processing, and operation. Measurements of the signals are presented, a comparison with analysis is shown and results are discussed. The goal of this study is to characterize the RF-vacuum interaction during normal operations. With a better understanding of the installed system response, methods for reducing the fault rate may be devised, ultimately leading to improvements in availability.
Apodized grating coupler using fully-etched nanostructures
International Nuclear Information System (INIS)
Wu Hua; Li Chong; Guo Xia; Li Zhi-Yong
2016-01-01
A two-dimensional apodized grating coupler for interfacing between single-mode fiber and photonic circuit is demonstrated in order to bridge the mode gap between the grating coupler and optical fiber. The grating grooves of the grating couplers are realized by columns of fully etched nanostructures, which are utilized to digitally tailor the effective refractive index of each groove in order to obtain the Gaussian-like output diffractive mode and then enhance the coupling efficiency. Compared with that of the uniform grating coupler, the coupling efficiency of the apodized grating coupler is increased by 4.3% and 5.7%, respectively, for the nanoholes and nanorectangles as refractive index tunes layer. (paper)
RF system design for the PEP-II B Factory
International Nuclear Information System (INIS)
Schwarz, H.; Rimmer, R.
1994-06-01
The paper presents an overview of the design of the RF system for the PEP-II B Factory. An RF station consists of either two or four single-cell cavities driven by a 1.2 MW klystron through a waveguide distribution network. A variety of feedback loops stabilize the RF and its interaction with the beam. System parameters and all the relevant parameters of klystron and cavities are given
RF power harvesting: a review on designing methodologies and applications
Tran, Le-Giang; Cha, Hyouk-Kyu; Park, Woo-Tae
2017-12-01
Wireless power transmission was conceptualized nearly a century ago. Certain achievements made to date have made power harvesting a reality, capable of providing alternative sources of energy. This review provides a summ ary of radio frequency (RF) power harvesting technologies in order to serve as a guide for the design of RF energy harvesting units. Since energy harvesting circuits are designed to operate with relatively small voltages and currents, they rely on state-of-the-art electrical technology for obtaining high efficiency. Thus, comprehensive analysis and discussions of various designs and their tradeoffs are included. Finally, recent applications of RF power harvesting are outlined.
Design optimization of structural parameters in double gate MOSFETs for RF applications
International Nuclear Information System (INIS)
Liang Jiale; Xiao Han; Huang Ru; Wang Pengfei; Wang Yangyuan
2008-01-01
Double gate (DG) MOSFETs have recently attracted much attention for both logic and analog/RF applications. In this paper we focus on the design consideration of DG devices for RF applications. The different influences of key structural parameters on RF characteristics are comprehensively studied and optimized, including body thickness, spacer length and source/drain raised height. The impact of the fluctuation of geometrical parameters of DG devices on RF figures-of-merit are estimated. In addition, different dominance of structural parameters for RF applications is studied in DG devices with different channel lengths. The dependence of RF performance on the gate length downscaling of DG devices is also discussed. The obtained results give the design guidelines for DG devices for RF applications
Design and manufacture of the RF power supply and RF transmission line for SANAEM project Prometheus
Turemen, G.; Ogur, S.; Ahiska, F.; Yasatekin, B.; Cicek, E.; Ozbey, A.; Kilic, I.; Unel, G.; Alacakir, A.
2017-08-01
A 1-5 MeV proton beamline is being built by the Turkish Atomic Energy Authority in collaboration with a number of graduate students from different universities. The primary goal of the project, is to acquire the design ability and manufacturing capability of all the components locally. SPP will be an accelerator and beam diagnostics test facility and it will also serve the detector development community with its low beam current. This paper discusses the design and construction of the RF power supply and the RF transmission line components such as its waveguide converters and its circulator. Additionally low and high power RF test results are presented to compare the performances of the locally produced components to the commercially available ones.
International Nuclear Information System (INIS)
Limborg-Deprey, C.
2010-01-01
Final dimensions for the LCLS RF gun are described. This gun, referred to as the LCLS gun, is a modified version of the UCLA/BNL/SLAC 1.6 cell S-Band RF gun (1), referred to as the prototype gun. The changes include a larger mode separation (15 MHz for the LCLS gun vs. 3.5 MHz for the prototype gun), a larger radius at the iris between the 2 cells, a reduced surface field on the curvature of the iris between the two cells, Z power coupling, increased cooling channels for operation at 120 Hz, dual rf feed, deformation tuning of the full cell, and field probes in both cells. Temporal shaping of the klystron pulse, to reduce the average power dissipated in the gun, has also been adopted. By increasing the mode separation, the amplitude of the 0-mode electric field on the cathode decreases from 10% of the peak on axis field for the prototype gun to less than 3% for the LCLS gun for the steady state fields. Beam performance is improved as shown by the PARMELA simulations. The gun should be designed to accept a future load lock system. Modifications follow the recommendations of our RF review committee (2). Files and reference documents are compiled in Section IV.
Effect of RF Parameters on Breakdown Limits in High-Vacuum X-Band Structures
International Nuclear Information System (INIS)
Dolgashev, Valery A.
2003-01-01
RF breakdown is one of the major factors determining performance of high power rf components and rf sources. RF breakdown limits working power and produces irreversible surface damage. The breakdown limit depends on the rf circuit, structure geometry, and rf frequency. It is also a function of the input power, pulse width, and surface electric and magnetic fields. In this paper we discuss multi-megawatt operation of X-band rf structures at pulse width on the order of one microsecond. These structures are used in rf systems of high gradient accelerators. Recent experiments at Stanford Linear Accelerator Center (SLAC) have explored the functional dependence of breakdown limit on input power and pulse width. The experimental data covered accelerating structures and waveguides. Another breakdown limit of accelerating structures was associated with high magnetic fields found in waveguide-to-structure couplers. To understand and quantify these limits we simulated 3D structures with the electrodynamics code Ansoft HFSS and the Particle-In-Cell code MAGIC3D. Results of these simulations together with experimental data will be discussed in this paper
RF current generation near the ion cyclotron frequency
International Nuclear Information System (INIS)
Watkins, J.G.
1982-01-01
An experiment has been conducted to measure unipolar currents driven by directional radio frequency waves in a cylindrical plasma mirror machine near the ion cyclotron frequency. The directional waves were launched using a four phase helical coupler which allowed the selection of both azimuthal mode number (m = +1) and direction of wave propagation. Plasma diagnostics include electron density measurements (4 mm microwave interferometer), electron temperature measurements (floating double probe), wave amplitude and coupling measurements (magnetic probes). RF power measurements (RF voltage and current probes) and RF driven plasma current measurements (Rogowski loops and current transformers). End electrodes provided a necessary external return path and an alternate method for measuring the current. Theoretical work includes an analytic approximation to the nonlinear problem of a particle in a traveling wave and computer simulations that extend this result. Nonlinear particle drifts other than trapping were found both with and without the presence of particle collisions
R.F. cavity design for the NSLS
International Nuclear Information System (INIS)
Batchelor, K.; Galayda, J.; Hawrylak, R.
1981-01-01
The r.f cavity design for the Booster, vuv ring and x-ray ring of the NSLS is described together with the mechanical design of tuners, coupling and monitoring loops and the temperature control systems. The results of higher order mode measurements as compared with Superfish calculations are also presented
Elements of the system for RF power input into linear accelerator-injector for booster
International Nuclear Information System (INIS)
Mazurov, E.V.; Mal'tsev, I.G.; Shalashov, I.M.
1981-01-01
The elements of the original system for RF power input into 30 MeV linear accelerator-injector for the IHEP proton synchrotron booster are considered. A 3 dB coaxial directional coupler (T-bridge) is describedd. The characteristics of the bridge containing elements and the parameters of ballast matched load are given [ru
RF Circuit Design in Nanometer CMOS
Nauta, Bram
2007-01-01
With CMOS technology entering the nanometer regime, the design of analog and RF circuits is complicated by low supply voltages, very non-linear (and nonquadratic) devices and large 1/f noise. At the same time, circuits are required to operate over increasingly wide bandwidths to implement modern
Ultrashort hybrid metal-insulator plasmonic directional coupler.
Noghani, Mahmoud Talafi; Samiei, Mohammad Hashem Vadjed
2013-11-01
An ultrashort plasmonic directional coupler based on the hybrid metal-insulator slab waveguide is proposed and analyzed at the telecommunication wavelength of 1550 nm. It is first analyzed using the supermode theory based on mode analysis via the transfer matrix method in the interaction region. Then the 2D model of the coupler, including transition arms, is analyzed using a commercial finite-element method simulator. The hybrid slab waveguide is composed of a metallic layer of silver and two dielectric layers of silica (SiO2) and silicon (Si). The coupler is optimized to have a minimum coupling length and to transfer maximum power considering the layer thicknesses as optimization variables. The resulting coupling length in the submicrometer region along with a noticeable power transfer efficiency are advantages of the proposed coupler compared to previously reported plasmonic couplers.
Design and development of Low Level RF (LLRF) control system
International Nuclear Information System (INIS)
Mandi, T.K.; Suman, S.; Pandey, H.K.; Bandyopadhyay, A.
2015-01-01
All the linear accelerator cavities of Radioactive Ion Beam have separate RF power amplifiers. In these accelerators, high stabilities of the order of ± 0.5% in amplitude and ± 0.5° in phase of RF signal inside the cavities are required for proper and efficient acceleration of RIB. For this purpose, a low level RF (LLRF) control system is being designed which includes amplitude and phase controllers to ensure efficient and stable operation of the RF accelerators. The RF output of the LLRF system is finally amplified and fed to the accelerator cavities. The LLRF system is based on IQ (In-phase and Quadrature) modulation-demodulation technique in which an IQ modulator and a demodulator has been used to control the amplitude and phase of the RF carrier signal. The HigH-speed DAC and ADC have been used for processing the in-phase (I) and quadrature-phase (Q) components of the RF signal. This system is a closed-loop feedback control system. The feedback signal is obtained from the pick-up of accelerator cavity. PID control method is used to regulate the amplitude and phase of the RF signal to the desired/set value. The control system is optimized for minimum response time with satisfactory performance. The transfer function of the PID controller and the RF cavity is compared with the transfer function of a first order system and the values of proportional gain (Kp), integral gain (Ti) and derivative gain (Td) are obtained from Matlab- Simulink Simulation. The PID controller has been implemented into a high speed microcontroller (LPC2478) for fast operation. A GUI has been developed in NI LabView software to monitor the Amplitude and Phase of the RF signal and control manually if required. The detailed design and development of the control system will be discussed in this paper. (author)
Ultra-low coupling loss fully-etched apodized grating coupler with bonded metal mirror
DEFF Research Database (Denmark)
Ding, Yunhong; Peucheret, Christophe; Ou, Haiyan
2014-01-01
A fully etched apodized grating coupler with bonded metal mirror is designed and demonstrated on the silicon-on-insulator platform, showing an ultra-low coupling loss of only 1.25 dB with 3 dB bandwidth of 69 nm.......A fully etched apodized grating coupler with bonded metal mirror is designed and demonstrated on the silicon-on-insulator platform, showing an ultra-low coupling loss of only 1.25 dB with 3 dB bandwidth of 69 nm....
Microfabrication of pre-aligned fiber bundle couplers using ultraviolet lithography of SU-8
Yang, Ren; Soper, Steven A.; Wang, Wanjun
2006-01-01
This paper describes the design, microfabrication and testing of a pre-aligned array of fiber couplers using direct UV-lithography of SU-8. The fiber coupler array includes an out-of-plane refractive microlens array and two fiberport collimator arrays. With the optical axis of the pixels parallel to the substrate, each pixel of the microlens array can be pre-aligned with the corresponding pixels of the fiberport collimator array as defined by the lithography mask design. This out-of-plane pol...
Evaluation of RF properties by orifice design for IFMIF RFQ
International Nuclear Information System (INIS)
Maebara, Sunao; Sugimoto, Masayoshi
2005-03-01
Orifices for the IFMIF RFQ have been designed and fabricated, and RF properties have been evaluated by a network analyzer. The designed orifices were installed into a vacuum port of the 1.1m-long RFQ mock-up module, and the resonant frequency and the phase difference between cavities were measured for a quadrupole operation mode of TE 210 . It was found that the RF properties are not affected on condition that slit direction with the same direction of current flow at the RFQ wall. Orifice conductance from 0.22 to 0.25 m 3 /sec by nitrogen conversion at room temperature was designed, and an ultimate pressure level of 5x10 -7 [Pa] was evaluated for the 4.1m-long central module for the IFMIF RFQ. It was concluded that the designed orifices are effective for RF properties and vacuum conductance in the IFMIF RFQ. (author)
Design of 6 MeV X-band electron linac for dual-head gantry radiotherapy system
Shin, Seung-wook; Lee, Seung-Hyun; Lee, Jong-Chul; Kim, Huisu; Ha, Donghyup; Ghergherehchi, Mitra; Chai, Jongseo; Lee, Byung-no; Chae, Moonsik
2017-12-01
A compact 6 MeV electron linac is being developed at Sungkyunkwan University, in collaboration with the Korea atomic energy research institute (KAERI). The linac will be used as an X-ray source for a dual-head gantry radiotherapy system. X-band technology has been employed to satisfy the size requirement of the dual-head gantry radiotherapy machine. Among the several options available, we selected a pi/2-mode, standing-wave, side-coupled cavity. This choice of radiofrequency (RF) cavity design is intended to enhance the shunt impedance of each cavity in the linac. An optimum structure of the RF cavity with a high-performance design was determined by applying a genetic algorithm during the optimization procedure. This paper describes the detailed design process for a single normal RF cavity and the entire structure, including the RF power coupler and coupling cavity, as well as the beam dynamics results.
Multi-MW K-Band Harmonic Multiplier: RF Source For High-Gradient Accelerator R & D
Solyak, N. A.; Yakovlev, V. P.; Kazakov, S. Yu.; Hirshfield, J. L.
2009-01-01
A preliminary design is presented for a two-cavity 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 at selected frequencies in K-band (18-26.5 GHz) using as an RF driver an XK-5 S-band klystron (2.856 GHz). The device is to be built with a TE111 rotating mode input cavity and interchangeable output cavities running in the TEn11 rotating mode, with n = 7,8,9 at 19.992, 22.848, and 25.704 GHz. An example for a 7th harmonic multiplier is described, using a 250 kV, 20 A injected laminar electron beam; with 10 MW of S-band drive power, 4.7 MW of 20-GHz output power is predicted. Details are described of the magnetic circuit, cavities, and output coupler.
RF microwave circuit design for wireless applications
Rohde, Ulrich L
2012-01-01
Provides researchers and engineers with a complete set of modeling, design, and implementation tools for tackling the newest IC technologies Revised and completely updated, RF/Microwave Circuit Design for Wireless Applications, Second Edition is a unique, state-of-the-art guide to wireless integrated circuit design that provides researchers and engineers with a complete set of modeling, design, and implementation tools for tackling even the newest IC technologies. It emphasizes practical design solutions for high-performance devices and circuitry, incorporating ample exa
Design and Optimization of AlN based RF MEMS Switches
Hasan Ziko, Mehadi; Koel, Ants
2018-05-01
Radio frequency microelectromechanical system (RF MEMS) switch technology might have potential to replace the semiconductor technology in future communication systems as well as communication satellites, wireless and mobile phones. This study is to explore the possibilities of RF MEMS switch design and optimization with aluminium nitride (AlN) thin film as the piezoelectric actuation material. Achieving low actuation voltage and high contact force with optimal geometry using the principle of piezoelectric effect is the main motivation for this research. Analytical and numerical modelling of single beam type RF MEMS switch used to analyse the design parameters and optimize them for the minimum actuation voltage and high contact force. An analytical model using isotropic AlN material properties used to obtain the optimal parameters. The optimized geometry of the device length, width and thickness are 2000 µm, 500 µm and 0.6 µm respectively obtained for the single beam RF MEMS switch. Low actuation voltage and high contact force with optimal geometry are less than 2 Vand 100 µN obtained by analytical analysis. Additionally, the single beam RF MEMS switch are optimized and validated by comparing the analytical and finite element modelling (FEM) analysis.
Arsenyev, Sergey A.; Temkin, Richard J.; Shchegolkov, Dmitry Yu.; Simakov, Evgenya I.; Boulware, Chase H.; Grimm, Terry L.; Rogacki, Adam R.
2016-08-01
We present a study of higher order mode (HOM) damping in the first multicell superconducting radio-frequency (SRF) cavity with a photonic band gap (PBG) coupler cell. Achieving higher average beam currents is particularly desirable for future light sources and particle colliders based on SRF energy-recovery linacs (ERLs). Beam current in ERLs is limited by the beam breakup instability, caused by parasitic HOMs interacting with the beam in accelerating cavities. A PBG cell incorporated in an accelerating cavity can reduce the negative effect of HOMs by providing a frequency selective damping mechanism, thus allowing significantly higher beam currents. The five-cell cavity with a PBG cell was designed and optimized for HOM damping. Monopole and dipole HOMs were simulated. The SRF cavity was fabricated and tuned. External quality factors for some HOMs were measured in a cold test. The measurements agreed well with the simulations.
Directory of Open Access Journals (Sweden)
Sergey A. Arsenyev
2016-08-01
Full Text Available We present a study of higher order mode (HOM damping in the first multicell superconducting radio-frequency (SRF cavity with a photonic band gap (PBG coupler cell. Achieving higher average beam currents is particularly desirable for future light sources and particle colliders based on SRF energy-recovery linacs (ERLs. Beam current in ERLs is limited by the beam breakup instability, caused by parasitic HOMs interacting with the beam in accelerating cavities. A PBG cell incorporated in an accelerating cavity can reduce the negative effect of HOMs by providing a frequency selective damping mechanism, thus allowing significantly higher beam currents. The five-cell cavity with a PBG cell was designed and optimized for HOM damping. Monopole and dipole HOMs were simulated. The SRF cavity was fabricated and tuned. External quality factors for some HOMs were measured in a cold test. The measurements agreed well with the simulations.
Design of ITER-FEAT RF heating and current drive systems
International Nuclear Information System (INIS)
Bosia, G.; Kobayashi, N.; Ioki, K.; Bibet, P.; Koch, R.; Chavan, R.; Tran, M.Q.; Takahashi, K.; Kuzikov, S.; Vdovin, V.
2001-01-01
Three radio frequency (RF) heating and current drive (H and CD) systems are being designed for ITER-FEAT: an electron cyclotron (EC), an ion cyclotron (IC) and a lower hybrid (LH) System. The launchers of the RF systems use four ITER equatorial ports and are fully interchangeable. They feature equal power outputs (20 MW/port), similar neutron shielding performance, and identical interfaces with the other machine components. An outline of the design is given in the paper. (author)
Quantitative analysis of coupler tuning
International Nuclear Information System (INIS)
Zheng Shuxin; Cui Yupeng; Chen Huaibi; Xiao Liling
2001-01-01
The author deduces the equation of coupler frequency deviation Δf and coupling coefficient β instead of only giving the adjusting direction in the process of matching coupler, on the basis of coupling-cavity chain equivalent circuits model. According to this equation, automatic measurement and quantitative display are realized on a measuring system. It contributes to industrialization of traveling-wave accelerators for large container inspection systems
Baking Arithmetic and Error Analyses for PEFP Fundamental Power Couplers
International Nuclear Information System (INIS)
Zhang, Liping; An, Sun; Tang, Yazhe; Cho, Yong Sub
2009-01-01
The Proton Engineering Frontier Project (PEFP) is considering developing and using SRF technology to accelerate a proton beam at 700 MHz in its present project and its extended project (PEP). The first section of the PEFP SRF linac (SCL) is composed of low-beta cryomodules. Each cryomodule has three 5-cell cavities and each cavity has one fundamental power coupler (FPC). Before the high power RF processing, each FPC needs to be baked out for 24 hours at 200 degrees Celsius ( .deg. C). The whole control system is described in reference, in this system, the temperature in the baking-box need to be changed according to three straight lines with different slope. This paper described how we can make the temperature of the baking-box changed according to the required values
Baking Arithmetic and Error Analyses for PEFP Fundamental Power Couplers
Energy Technology Data Exchange (ETDEWEB)
Zhang, Liping; An, Sun; Tang, Yazhe; Cho, Yong Sub [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2009-05-15
The Proton Engineering Frontier Project (PEFP) is considering developing and using SRF technology to accelerate a proton beam at 700 MHz in its present project and its extended project (PEP). The first section of the PEFP SRF linac (SCL) is composed of low-beta cryomodules. Each cryomodule has three 5-cell cavities and each cavity has one fundamental power coupler (FPC). Before the high power RF processing, each FPC needs to be baked out for 24 hours at 200 degrees Celsius ( .deg. C). The whole control system is described in reference, in this system, the temperature in the baking-box need to be changed according to three straight lines with different slope. This paper described how we can make the temperature of the baking-box changed according to the required values.
Computer codes for RF cavity design
International Nuclear Information System (INIS)
Ko, K.
1992-08-01
In RF cavity design, numerical modeling is assuming an increasingly important role with the help of sophisticated computer codes and powerful yet affordable computers. A description of the cavity codes in use in the accelerator community has been given previously. The present paper will address the latest developments and discuss their applications to cavity toning and matching problems
Rf probe technology for the next generation of technological plasmas
International Nuclear Information System (INIS)
Law, V.J.; Kenyon, A.J.; Thornhill, N.F.; Seeds, A.J.; Batty, I.
2001-01-01
We describe radio frequency (rf) analysis of technological plasmas at the 13.56 MHz fundamental drive frequency and integer narrow-band harmonics up to n = 9. In particular, we demonstrate the use of harmonic amplitude information as a process end-point diagnostic. Using very high frequency (vhf) techniques, we construct non-invasive ex situ remote-coupled probes: a diplexer, an equal-ratio-arm bridge, and a dual directional coupler used as a single directional device. These probes bolt into the plasma-tool 50 Ω transmission-line between the rf generator and matching network, and hence do not require modification of the plasma tool. The 50 Ω probe environment produces repeatable measurements of the chamber capacitance and narrow-band harmonic amplitude with an end-point detection sensitivity corresponding to a 2 dB change in the harmonic amplitude with the removal of 1 cm 2 of photoresist. The methodology and design of an instrument for the measurement of the plasma-tool frequency response, and the plasma harmonic amplitude and phase response are examined. The instrument allows the monitoring of the plasma phase delay, plasma-tool short- and long-term ageing, and process end-point prediction. (author)
Designing focusing solenoids for superconducting RF accelerators
Energy Technology Data Exchange (ETDEWEB)
Davis, G.; Kashikhin, V.V.; Page, T.; Terechkine, I.; Tompkins, J.; Wokas, T.; /Fermilab
2006-08-01
The design of a focusing solenoid for use in a superconducting RF linac requires resolving a range of problems with conflicting requirements. Providing the required focusing strength contradicts the goal of minimizing the stray field on the surfaces of adjacent superconducting RF cavities. The requirement of a compact solenoid, able to fit into a gap between cavities, contradicts the need of mechanical support necessary to restrain electromagnetic forces that can result in coil motion and subsequent quenching. In this report we will attempt to address these and other issues arising during the development of focusing solenoids. Some relevant test data will also be presented.
Industrial RF Linac Experiences and Laboratory Interactions
Peiniger, M
2004-01-01
Since more than two decades ACCEL Instruments GmbH at Bergisch Gladbach (formerly Siemens/Interatom) is supplying the worldwide accelerator labs with key components like rf cavities and power couplers, s.c. magnets, insertion devices, vacuum chambers and x-ray beamline equipment. Starting with the design and production of turn key SRF accelerating modules in the late 80th, meanwhile ACCEL is engineering, manufacturing, on site commissioning and servicing complete accelerators with guaranteed beam performance. Today, with a staff of more than 100 physicists and engineers and about the same number of manufacturing specialists in our dedicated production facilities, ACCEL's know how and sales volume in this field has accumulated to more than 2000 man years and several hundred Mio €, respectively. Basis of our steady development is a cooperative partnership with the world leading research labs in the respective fields. As an example, for the supply of a turn key 100 MeV injector linac for the Swiss Ligh...
Apodized grating coupler using fully-etched nanostructures
Wu, Hua; Li, Chong; Li, Zhi-Yong; Guo, Xia
2016-08-01
A two-dimensional apodized grating coupler for interfacing between single-mode fiber and photonic circuit is demonstrated in order to bridge the mode gap between the grating coupler and optical fiber. The grating grooves of the grating couplers are realized by columns of fully etched nanostructures, which are utilized to digitally tailor the effective refractive index of each groove in order to obtain the Gaussian-like output diffractive mode and then enhance the coupling efficiency. Compared with that of the uniform grating coupler, the coupling efficiency of the apodized grating coupler is increased by 4.3% and 5.7%, respectively, for the nanoholes and nanorectangles as refractive index tunes layer. Project supported by the National Natural Science Foundation of China (Grant Nos. 61222501, 61335004, and 61505003), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20111103110019), the Postdoctoral Science Foundation of Beijing Funded Project, China (Grant No. Q6002012201502), and the Science and Technology Research Project of Jiangxi Provincial Education Department, China (Grant No. GJJ150998).
Progress on the RF Coupling Coil Module Design for the MICE Channel
International Nuclear Information System (INIS)
Li, D.; Green, M.A.; Virostek, S.P.; Zisman, M.S.; Lau, W.; White, A.E.; Yang, S.Q.
2005-01-01
We describe the progress on the design of the RF coupling coil (RFCC) module for the international Muon Ionization Cooling Experiment (MICE) at Rutherford Appleton Laboratory (RAL) in the UK. The MICE cooling channel design consists of one SFOFO cell that is similar to that of the US Study-II of a neutrino factory. The MICE RFCC module comprises a superconducting solenoid, mounted around four normal conducting 201.25-MHz RF cavities. Each cavity has a pair of thin curved beryllium windows to close the conventional open beam irises, which allows for independent control of the phase in each cavity and for the RF power to be fed separately. The coil package that surrounds the RF cavities is mounted on a vacuum vessel. The RF vacuum is shared between the cavities and the vacuum vessel around the cavities such that there is no differential pressure on the thin beryllium windows. This paper discusses the design progress of the RFCC module and the fabrication progress of a prototype 201.25-MHz cavity
Digitally-assisted analog and RF CMOS circuit design for software-defined radio
Okada, Kenichi
2011-01-01
This book describes the state-of-the-art in RF, analog, and mixed-signal circuit design for Software Defined Radio (SDR). It synthesizes for analog/RF circuit designers the most important general design approaches to take advantage of the most recent CMOS technology, which can integrate millions of transistors, as well as several real examples from the most recent research results.
Computer codes for RF cavity design
International Nuclear Information System (INIS)
Ko, K.
1992-01-01
In RF cavity design, numerical modeling is assuming an increasingly important role with the help of sophisticated computer codes and powerful yet affordable computers. A description of the cavity codes in use in the accelerator community has been given previously. The present paper will address the latest developments and discuss their applications to cavity tuning and matching problems. (Author) 8 refs., 10 figs
Brunner, O C; Valuch, D
2003-01-01
The counter-rotating proton beams in the Large Hadron Collider (LHC) will be captured and then accelerated to their final energies of 2 x 7 TeV by two identical 400 MHz RF systems. The RF power source required for each beam comprises eight 300 kW klystrons. The output power of each klystron is fed via a circulator and a waveguide line to the input coupler of a single-cell super-conducting (SC) cavity. Four klystrons are powered by a 100 kV, 40A AC/DC power converter, previously used for the operation of the LEP klystrons. A five-gap thyratron crowbar protects the four klystrons in each of these units. The technical specification and measured performance of the various high-power elements are discussed. These include the 400MHz/300kW klystrons with emphasis on their group delay and the three-port circulators, which have to cope with peak reflected power levels up to twice the simultaneously applied incident power of 300 kW. In addition, a novel ferrite loaded waveguide absorber, used as termination for port No...
Mu, Jinfeng; Sefünç, Mustafa; García Blanco, Sonia Maria
2014-01-01
The integration of rare-earth doped double tungstate waveguide amplifiers onto passive technology platforms enables the on-chip amplification of very high bit rate signals. In this work, a methodology for the optimized design of vertical adiabatic couplers between a passive Si3N4 waveguide and the
Grating-assisted surface acoustic wave directional couplers
Golan, G.; Griffel, G.; Seidman, A.; Croitoru, N.
1991-07-01
Physical properties of novel grating-assisted Y directional couplers are examined using the coupled-mode theory. A general formalism for the analysis of the lateral perturbed directional coupler properties is presented. Explicit expressions for waveguide key parameters such as coupling length, grating period, and other structural characterizations, are obtained. The influence of other physical properties such as time and frequency response or cutoff conditions are also analyzed. A plane grating-assisted directional coupler is presented and examined as a basic component in the integrated acoustic technology.
Mode conversion in hybrid optical fiber coupler
Stasiewicz, Karol A.; Marc, P.; Jaroszewicz, Leszek R.
2012-04-01
Designing of all in-line fiber optic systems with a supercontinuum light source gives some issues. The use of a standard single mode fiber (SMF) as an input do not secure single mode transmission in full wavelength range. In the paper, the experimental results of the tested hybrid fiber optic coupler were presented. It was manufactured by fusing a standard single mode fiber (SMF28) and a photonic crystal fiber (PCF). The fabrication process is based on the standard fused biconical taper technique. Two types of large mode area fibers (LMA8 and LAM10 NKT Photonics) with different air holes arrangements were used as the photonic crystal fiber. Spectral characteristics within the range of 800 nm - 1700 nm were presented. All process was optimized to obtain a mode conversion between SMF and PCF and to reach a single mode transmission in the PCF output of the coupler.
Wintucky, Edwin G.; Simons, Rainee N.
2014-01-01
This paper presents the design, fabrication and test results for a novel waveguide multimode directional coupler (MDC). The coupler fabricated from two dissimilar waveguides is capable of isolating the power at the second harmonic frequency from the fundamental power at the output port of a traveling-wave tube (TWT). In addition to accurate power measurements at harmonic frequencies, a potential application of the MDC is in the design of a beacon source for atmospheric propagation studies at millimeter-wave frequencies.
Fully etched apodized grating coupler on the SOI platform with −058 dB coupling efficiency
DEFF Research Database (Denmark)
Ding, Yunhong; Peucheret, Christophe; Ou, Haiyan
2014-01-01
We design and fabricate an ultrahigh coupling efficiency (CE) fully etched apodized grating coupler on the silicon- on-insulator (SOI) platform using subwavelength photonic crystals and bonded aluminum mirror. Fabrication error sensitivity andcoupling angle dependence are experimentally investiga......We design and fabricate an ultrahigh coupling efficiency (CE) fully etched apodized grating coupler on the silicon- on-insulator (SOI) platform using subwavelength photonic crystals and bonded aluminum mirror. Fabrication error sensitivity andcoupling angle dependence are experimentally...
Modeling and design techniques for RF power amplifiers
Raghavan, Arvind; Laskar, Joy
2008-01-01
The book covers RF power amplifier design, from device and modeling considerations to advanced circuit design architectures and techniques. It focuses on recent developments and advanced topics in this area, including numerous practical designs to back the theoretical considerations. It presents the challenges in designing power amplifiers in silicon and helps the reader improve the efficiency of linear power amplifiers, and design more accurate compact device models, with faster extraction routines, to create cost effective and reliable circuits.
Energy Technology Data Exchange (ETDEWEB)
Saha, Tapas Kumar; Zhou Weidong [University of Texas at Arlington, Department of Electrical Engineering, NanoFAB Center, Arlington, TX 76019-0072 (United States)
2009-04-21
We report here the design of a new type of high efficiency grating coupler, based on single crystalline Si nanomembrane overlay and stacking. Such high efficiency diffractive grating couplers are designed for the purpose of coupling light between single mode fibres and nanophotonic waveguides, and for the coupling between multiple photonic interconnect layers for compact three-dimensional vertical integration. Two-dimensional model simulation based on eigenmode expansion shows a diffractive power-up efficiency of 81% and a fibre coupling efficiency of 64%. With nanomembrane stacking, it is feasible to integrate the side-distributed Bragg reflector and bottom reflector, which can lead to the diffractive power-up efficiency and the fibre coupling efficiency of 97% and 73.5%, respectively. For a negatively detuned coupler, the bottom reflector is not needed, and the diffractive power-up efficiency can reach 98% over a large spectral range. The device is extremely tolerant to fabrication errors.
A photocathode rf gun design for a mm-wave linac-based FEL
Energy Technology Data Exchange (ETDEWEB)
Nassiri, A.; Berenc, T,; Foster, J.; Waldschmidt, G.; Zhou, J.
1995-07-01
In recent years, advances in the rf gun technology have made it possible to produce small beam emittances suitable for short period microundulators which take advantage of the low emittance beam to reduce the wavelength of FELs. At the Advanced Photon Source, we are studying the design of a compact 50-MeV superconducting mm-wave linac-based FEL for the production of short wavelengths ({approximately}300 nm) to carry out FEL demonstration experiments. The electron source considered for the linac is a 30- GHz, 3 1/2-cell {pi}-mode photocathode rf gun. For cold model rf measurements a 15-GHz prototype structure was fabricated. Here we report on the design, numerical modelling and the initial cold-model rf measurement results on the 15-GHz prototype structure.
A photocathode rf gun design for a mm-wave linac-based FEL
International Nuclear Information System (INIS)
Nassiri, A.; Berenc, T.; Foster, J.; Waldschmidt, G.; Zhou, J.
1995-01-01
In recent years, advances in the rf gun technology have made it possible to produce small beam emittances suitable for short period microundulators which take advantage of the low emittance beam to reduce the wavelength of FELs. At the Advanced Photon Source, we are studying the design of a compact 50-MeV superconducting mm-wave linac-based FEL for the production of short wavelengths (∼300 nm) to carry out FEL demonstration experiments. The electron source considered for the linac is a 30- GHz, 3 1/2-cell π-mode photocathode rf gun. For cold model rf measurements a 15-GHz prototype structure was fabricated. Here we report on the design, numerical modelling and the initial cold-model rf measurement results on the 15-GHz prototype structure
Modeling and simulation for RF system design
Frevert, Ronny; Jancke, Roland; Knöchel, Uwe; Schwarz, Peter; Kakerow, Ralf; Darianian, Mohsen
2005-01-01
Focusing on RF specific modeling and simulation methods, and system and circuit level descriptions, this work contains application-oriented training material. Accompanied by a CD- ROM, it combines the presentation of a mixed-signal design flow, an introduction into VHDL-AMS and Verilog-A, and the application of commercially available simulators.
Design for the National RF Test Facility at ORNL
International Nuclear Information System (INIS)
Gardner, W.L.; Hoffman, D.J.; Becraft, W.R.
1983-01-01
Conceptual and preliminary engineering design for the National RF Test Facility at Oak Ridge National Laboratory (ORNL) has been completed. The facility will comprise a single mirror configuration embodying two superconducting development coils from the ELMO Bumpy Torus Proof-of-Principle (EBT-P) program on either side of a cavity designed for full-scale antenna testing. The coils are capable of generating a 1.2-T field at the axial midpoint between the coils separated by 1.0 m. The vacuum vessel will be a stainless steel, water-cooled structure having an 85-cm-radius central cavity. The facility will have the use of a number of continuous wave (cw), radio-frequency (rf) sources at levels including 600 kW at 80 MHz and 100 kW at 28 GHz. Several plasma sources will provide a wide range of plasma environments, including densities as high as approx. 5 x 10 13 cm -3 and temperatures on the order of approx. 10 eV. Furthermore, a wide range of diagnostics will be available to the experimenter for accurate appraisal of rf testing
Chen, George F R; Ong, Jun Rong; Ang, Thomas Y L; Lim, Soon Thor; Png, Ching Eng; Tan, Dawn T H
2017-08-03
Broadband Silicon-On-Insulator (SOI) directional couplers are designed based on a combination of curved and straight coupled waveguide sections. A design methodology based on the transfer matrix method (TMM) is used to determine the required coupler section lengths, radii, and waveguide cross-sections. A 50/50 power splitter with a measured bandwidth of 88 nm is designed and fabricated, with a device footprint of 20 μm × 3 μm. In addition, a balanced Mach-Zehnder interferometer is fabricated showing an extinction ratio of >16 dB over 100 nm of bandwidth.
Vidojkovic - Andjelovic, M.; Tang, van der J.D.; Baltus, P.G.M.; Roermund, van A.H.M.
2005-01-01
In today's world, new communication standards evolve fast, putting a significant burden on set makers and RFIC designer houses to bring integrated and cheap solutions quickly into the market place. The shift towards flexible RF systems that can support a range of applications via adjustability and
A linear atomic quantum coupler
Energy Technology Data Exchange (ETDEWEB)
El-Orany, Faisal A A [Department of Mathematics and computer Science, Faculty of Science, Suez Canal University 41522, Ismailia (Egypt); Wahiddin, M R B, E-mail: el_orany@hotmail.co, E-mail: faisal.orany@mimos.m, E-mail: mridza@mimos.m [Cyberspace Security Laboratory, MIMOS Berhad, Technology Park Malaysia, 57000 Kuala Lumpur (Malaysia)
2010-04-28
In this paper we develop the notion of the linear atomic quantum coupler. This device consists of two modes propagating into two waveguides, each of which includes a localized atom. These waveguides are placed close enough to allow exchange of energy between them via evanescent waves. Each mode interacts with the atom in the same waveguide in the standard way as the Jaynes-Cummings model (JCM) and with the atom-mode system in the second waveguide via the evanescent wave. We present the Hamiltonian for this system and deduce its wavefunction. We investigate the atomic inversions and the second-order correlation function. In contrast to the conventional coupler the atomic quantum coupler is able to generate nonclassical effects. The atomic inversions can exhibit a long revival-collapse phenomenon as well as subsidiary revivals based on the competition among the switching mechanisms in the system. Finally, under certain conditions the system can yield the results of the two-mode JCM.
Cpl6: The New Extensible, High-Performance Parallel Coupler forthe Community Climate System Model
Energy Technology Data Exchange (ETDEWEB)
Craig, Anthony P.; Jacob, Robert L.; Kauffman, Brain; Bettge,Tom; Larson, Jay; Ong, Everest; Ding, Chris; He, Yun
2005-03-24
Coupled climate models are large, multiphysics applications designed to simulate the Earth's climate and predict the response of the climate to any changes in the forcing or boundary conditions. The Community Climate System Model (CCSM) is a widely used state-of-art climate model that has released several versions to the climate community over the past ten years. Like many climate models, CCSM employs a coupler, a functional unit that coordinates the exchange of data between parts of climate system such as the atmosphere and ocean. This paper describes the new coupler, cpl6, contained in the latest version of CCSM,CCSM3. Cpl6 introduces distributed-memory parallelism to the coupler, a class library for important coupler functions, and a standardized interface for component models. Cpl6 is implemented entirely in Fortran90 and uses Model Coupling Toolkit as the base for most of its classes. Cpl6 gives improved performance over previous versions and scales well on multiple platforms.
Performance of the Crowbar of the LHC High Power RF System
Ravidà, G; Valuch, D
2012-01-01
The counter-rotating proton beams in the Large Hadron Collider (LHC) are captured and accelerated to their final energies by two identical 400 MHz Radio Frequency (RF) systems. The RF power source required for each beam comprises eight 300 kW klystrons. The output power of each klystron is fed via a circulator and a waveguide line to the input coupler of a single-cell superconducting (SC) cavity. Each unit of four klystrons is powered by a -100kV/40A AC/DC power converter. A fast protection system (crowbar) protects the four klystrons in each of these units. Although the LHC RF system has shown has very good performance, operational experience has shown that the five-gap double-ended thyratrons used in the crowbar system suffer, from time to time, from auto-firing, which result in beam dumps. This paper presents the recent results obtained with an alternative solution based on solid state thyristors. Comparative measurements with the thyratron are shown.
Wireless power transfer magnetic couplers
Wu, Hunter; Gilchrist, Aaron; Sealy, Kylee
2016-01-19
A magnetic coupler is disclosed for wireless power transfer systems. A ferrimagnetic component is capable of guiding a magnetic field. A wire coil is wrapped around at least a portion of the ferrimagnetic component. A screen is capable of blocking leakage magnetic fields. The screen may be positioned to cover at least one side of the ferrimagnetic component and the coil. A distance across the screen may be at least six times an air gap distance between the ferrimagnetic component and a receiving magnetic coupler.
Conceptual design of independently tunable cells RF gun with external injecting structure
International Nuclear Information System (INIS)
Liang Junjun; Feng Guangyao; Pei Yuanji; Pang Jian
2012-01-01
To obtain the micro-pulse bunch with the order of hundred femtoseconds length and high repetition rate, the pa- per proposes the independently tunable cells (ITC) RF gun, which has a double-cell structure with the cells being power fed independently. By choosing appropriate feeding power and phase of the two cells, this ITC-RF gun can achieve bunches of excellent characteristics. Additionally, the application of a-magnet and laser system can be avoided, which leads to more compact layout. An external injecting ITC-RF gun (DC-ITC-RF gun) structure is designed accordingly. The external injecting structure can increase beam current, decrease energy spread, and cancel the back-bombardment effect almost completely. By means of 1-D and 3- D beam dynamics calculation with different structure parameters, a group of RF parameters are obtained for better beam characteristics. Then the paper designs a pre-injector so that particles can be accelerated to 10 MeV. By choosing appropriate feeding power and incident particle phase for the pre-injector, the bunch length can be further compressed. (authors)
Advances in analog and RF IC design for wireless communication systems
Manganaro, Gabriele
2013-01-01
Advances in Analog and RF IC Design for Wireless Communication Systems gives technical introductions to the latest and most significant topics in the area of circuit design of analog/RF ICs for wireless communication systems, emphasizing wireless infrastructure rather than handsets. The book ranges from very high performance circuits for complex wireless infrastructure systems to selected highly integrated systems for handsets and mobile devices. Coverage includes power amplifiers, low-noise amplifiers, modulators, analog-to-digital converters (ADCs) and digital-to-analog converters
Arsenyev, Sergey A.; Temkin, Richard J.; Haynes, W. Brian; Shchegolkov, Dmitry Yu.; Simakov, Evgenya I.; Tajima, Tsuyoshi; Boulware, Chase H.; Grimm, Terrence L.; Rogacki, Adam R.
2016-05-01
We present results from cryogenic tests of the multi-cell superconducting radio frequency (SRF) cavity with a photonic band gap (PBG) coupler cell. Achieving high average beam currents is particularly desirable for future light sources and particle colliders based on SRF energy-recovery-linacs (ERLs). Beam current in ERLs is limited by the beam break-up instability, caused by parasitic higher order modes (HOMs) interacting with the beam in accelerating cavities. A PBG cell incorporated in an accelerating cavity can reduce the negative effect of HOMs by providing a frequency selective damping mechanism, thus allowing significantly higher beam currents. The multi-cell cavity was designed and fabricated of niobium. Two cryogenic (vertical) tests were conducted. The high unloaded Q-factor was demonstrated at a temperature of 4.2 K at accelerating gradients up to 3 MV/m. The measured value of the unloaded Q-factor was 1.55 × 108, in agreement with prediction.
A novel bridge coupler for SSC coupled cavity linac
International Nuclear Information System (INIS)
Yao, C.G.; Chang, C.R.; Funk, W.
1992-01-01
A novel magnetically coupled multi-cavity bridge coupler is proposed for SSC Coupled-Cavity-Linac (CCL). The bridge coupler is a five cell disc-loaded waveguide with a small central aperture used for measurement and two large curved coupling slots near the edge on each disc. The two coupling slots on the adjacent disc are rotated 90 degrees in orientation to reduce the direct coupling. This type of structure is capable of producing very large coupling (>10% in our longest bridge coupler). Also because of the small opening on the discs, the high-order-modes are very far (> 300 MHz) above the operating mode. Thus for long bridge couplers, the magnetic coupled structure should provide maximum coupling with minimum mode mixing problems. In this paper both physics and engineering issues of this new bridge coupler are presented. (Author) 5 refs., 2 tabs., 6 figs
High-power rf pulse compression with SLED-II at SLAC
International Nuclear Information System (INIS)
Nantista, C.
1993-04-01
Increasing the peak rf power available from X-band microwave tubes by means of rf pulse compression is envisioned as a way of achieving the few-hundred-megawatt power levels needed to drive a next-generation linear collider with 50--100 MW klystrons. SLED-II is a method of pulse compression similar in principal to the SLED method currently in use on the SLC and the LEP injector linac. It utilizes low-los resonant delay lines in place of the storage cavities of the latter. This produces the added benefit of a flat-topped output pulse. At SLAC, we have designed and constructed a prototype SLED-II pulse-compression system which operates in the circular TE 01 mode. It includes a circular-guide 3-dB coupler and other novel components. Low-power and initial high-power tests have been made, yielding a peak power multiplication of 4.8 at an efficiency of 40%. The system will be used in providing power for structure tests in the ASTA (Accelerator Structures Test Area) bunker. An upgraded second prototype will have improved efficiency and will serve as a model for the pulse compression system of the NLCTA (Next Linear Collider Test Accelerator)
Short-range wireless communication fundamentals of RF system design and application
Bensky, Alan
2004-01-01
The Complete "Tool Kit for the Hottest Area in RF/Wireless Design!Short-range wireless-communications over distances of less than 100 meters-is the most rapidly growing segment of RF/wireless engineering. Alan Bensky is an internationally recognized expert in short-range wireless, and this new edition of his bestselling book is completely revised to cover the latest developments in this fast moving field.You'll find coverage of such cutting-edge topics as: architectural trends in RF/wireless integrated circuits compatibility and conflict issues between differen
UV written compact broadband optical couplers
DEFF Research Database (Denmark)
Olivero, Massimo; Svalgaard, Mikael
2005-01-01
In this paper the first demonstration of compact asymmetric directional couplers made by UV writing is presented. The combined performance in terms bandwidth, loss and compactness exceeds that reported using other, more elaborate fabrication techniques.......In this paper the first demonstration of compact asymmetric directional couplers made by UV writing is presented. The combined performance in terms bandwidth, loss and compactness exceeds that reported using other, more elaborate fabrication techniques....
Mizutani, Akio; Eto, Yohei; Kikuta, Hisao
2017-12-01
A grating coupler with a trapezoidal hole array was designed and fabricated for perfectly vertical light coupling between a single-mode optical fiber and a silicon waveguide on a silicon-on-insulator (SOI) substrate. The grating coupler with an efficiency of 53% was computationally designed at a 1.1-µm-thick buried oxide (BOX) layer. The grating coupler and silicon waveguide were fabricated on the SOI substrate with a 3.0-µm-thick BOX layer by a single full-etch process. The measured coupling efficiency was 24% for TE-polarized light at 1528 nm wavelength, which was 0.69 times of the calculated coupling efficiency for the 3.0-µm-thick BOX layer.
State-Of High Brightness RF Photo-Injector Design
Ferrario, Massimo; Clendenin, Jym; Palmer, Dennis; Rosenzweig, James; Serafini, Luca
2000-04-01
The art of designing optimized high brightness electron RF Photo-Injectors has moved in the last decade from a cut and try procedure, guided by experimental experience and time consuming particle tracking simulations, up to a fast parameter space scanning, guided by recent analytical results and a fast running semi-analytical code, so to reach the optimum operating point which corresponds to maximum beam brightness. Scaling laws and the theory of invariant envelope provide to the designers excellent tools for a first parameters choice and the code HOMDYN, based on a multi-slice envelope description of the beam dynamics, is tailored to describe the space charge dominated dynamics of laminar beams in presence of time dependent space charge forces, giving rise to a very fast modeling capability for photo-injectors design. We report in this talk the results of a recent beam dynamics study, motivated by the need to redesign the LCLS photoinjector. During this work a new effective working point for a split RF photoinjector has been discovered by means of the previous mentioned approach. By a proper choice of rf gun and solenoid parameters, the emittance evolution shows a double minimum behavior in the drifting region. If the booster is located where the relative emittance maximum and the envelope waist occur, the second emittance minimum can be shifted at the booster exit and frozen at a very low level (0.3 mm-mrad for a 1 nC flat top bunch), to the extent that the invariant envelope matching conditions are satisfied.
Research on DC-RF superconducting photocathode injector for high average power FELs
International Nuclear Information System (INIS)
Zhao Kui; Hao Jiankui; Hu Yanle; Zhang Baocheng; Quan Shengwen; Chen Jiaer; Zhuang Jiejia
2001-01-01
To obtain high average current electron beams for a high average power Free Electron Laser (FEL), a DC-RF superconducting injector is designed. It consists of a DC extraction gap, a 1+((1)/(2)) superconducting cavity and a coaxial input system. The DC gap, which takes the form of a Pierce configuration, is connected to the 1+((1)/(2)) superconducting cavity. The photocathode is attached to the negative electrode of the DC gap. The anode forms the bottom of the ((1)/(2)) cavity. Simulations are made to model the beam dynamics of the electron beams extracted by the DC gap and accelerated by the superconducting cavity. High quality electron beams with emittance lower than 3 π-mm-mrad can be obtained. The optimization of experiments with the DC gap, as well as the design of experiments with the coaxial coupler have all been completed. An optimized 1+((1)/(2)) superconducting cavity is in the process of being studied and manufactured
A design and performance analysis tool for superconducting RF systems
International Nuclear Information System (INIS)
Schilcher, T.; Simrock, S.N.; Merminga, L.; Wang, D.X.
1997-01-01
Superconducting rf systems are usually operated with continuous rf power or with rf pulse lengths exceeding 1 ms to maximize the overall wall plug power efficiency. Typical examples are CEBAF at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) and the TESLA Test Facility at DESY. The long pulses allow for effective application of feedback to stabilize the accelerating field in presence of microphonics, Lorentz force detuning, and fluctuations of the beam current. In this paper the authors describe a set of tools to be used with MATLAB and SIMULINK, which allow to analyze the quality of field regulation for a given design. The tools include models for the cavities, the rf power source, the beam, sources of field perturbations, and the rf feedback system. The rf control relevant electrical and mechanical characteristics of the cavity are described in form of time-varying state space models. The power source is modeled as a current generator and includes saturation characteristics and noise.An arbitrary time structure can be imposed on the beam current to reflect a macro-pulse structure and bunch charge fluctuations. For rf feedback several schemes can be selected: Traditional amplitude and phase control as well as I/Q control. The choices for the feedback controller include analog or digital approaches and various choices of frequency response. Feed forward can be added to further suppress repetitive errors. The results of a performance analysis of the CEBAF and the TESLA Linac rf system using these tools are presented
Efficient Direct-Matching Rectenna Design for RF Power Transfer Applications
Keyrouz, Shady; Visser, Huib
2013-12-01
This paper presents the design, simulation, fabrication and measurements of a 50 ohm rectenna system. The paper investigates each part (in terms of input impedance) of the rectenna system starting from the antenna, followed by the matching network, to the rectifier. The system consists of an antenna, which captures the transmitted RF signal, connected to a rectifier which converts the AC captured signal into a DC power signal. For maximum power transfer, a matching network is designed between the rectifier and the antenna. At an input power level of -10 dBm, the system is able to achieve an RF/DC power conversion efficiency of 49.7%.
Efficient Direct-Matching Rectenna Design for RF Power Transfer Applications
International Nuclear Information System (INIS)
Keyrouz, Shady; Visser, Huib
2013-01-01
This paper presents the design, simulation, fabrication and measurements of a 50 ohm rectenna system. The paper investigates each part (in terms of input impedance) of the rectenna system starting from the antenna, followed by the matching network, to the rectifier. The system consists of an antenna, which captures the transmitted RF signal, connected to a rectifier which converts the AC captured signal into a DC power signal. For maximum power transfer, a matching network is designed between the rectifier and the antenna. At an input power level of −10 dBm, the system is able to achieve an RF/DC power conversion efficiency of 49.7%
Energy Technology Data Exchange (ETDEWEB)
Zanotto, Simone; Melloni, Andrea [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)
2016-04-28
By hybrid integration of plasmonic and dielectric waveguide concepts, it is shown that nearly perfect coherent absorption can be achieved in a co-propagating coupler geometry. First, the operating principle of the proposed device is detailed in the context of a more general 2 × 2 lossy coupler formalism. Then, it is shown how to tune the device in a wide region of possible working points, its broadband operation, and the tolerance to fabrication uncertainties. Finally, a complete picture of the electromagnetic modes inside the hybrid structure is analyzed, shining light onto the potentials which the proposed device holds in view of classical and quantum signal processing, nonlinear optics, polarization control, and sensing.
Energy Technology Data Exchange (ETDEWEB)
Yadav, Rana Pratap, E-mail: ranayadav97@gmail.com; Kumar, Sunil; Kulkarni, S. V. [Thapar University, Patiala, Punjab 147004, India and Institute for Plasma Research, Gandhinagar 382428 (India)
2016-01-15
Design and developmental procedure of strip-line based 1.5 MW, 30-96 MHz, ultra-wideband high power 3 dB hybrid coupler has been presented and its applicability in ion cyclotron resonance heating (ICRH) in tokamak is discussed. For the high power handling capability, spacing between conductors and ground need to very high. Hence other structural parameters like strip-width, strip thickness coupling gap, and junction also become large which can be gone upto optimum limit where various constrains like fabrication tolerance, discontinuities, and excitation of higher TE and TM modes become prominent and significantly deteriorates the desired parameters of the coupled lines system. In designed hybrid coupler, two 8.34 dB coupled lines are connected in tandem to get desired coupling of 3 dB and air is used as dielectric. The spacing between ground and conductors are taken as 0.164 m for 1.5 MW power handling capability. To have the desired spacing, each of 8.34 dB segments are designed with inner dimension of 3.6 × 1.0 × 40 cm where constraints have been significantly realized, compensated, and applied in designing of 1.5 MW hybrid coupler and presented in paper.
International Nuclear Information System (INIS)
Pascual, Joseph; Raoul, J.-C.
1978-04-01
The complex experimental devices used in high energy physics require the use of minicomputers. The latter are coupled to the detectors using the CAMAC standard which has been adopted by the majority of high energy physics laboratories, much to the ease of international collaboration. The performance of industrially available interfaces having shown to be inadequate, the DPhPE has undertaken the development of a multibranche CAMAC/PDP 11-45 coupler. This system can control up to 49 crates shared out between 7 branches. It consists of a programmed channel and up to three high speed (556 Kwords/second) automatic channels. The four channels can work simultaneously through time sharing. The coupler includes a LAM handling system. The correspondent software has been developed simultaneously: the monitor is an extended version of the RT 11 system supplied by the manufacturer. This interface has been used so far in five experiments on the CERN PS and SPS. Besides this publication, intended to give a description of the coupler, a user's utilisation manuel exists in English [fr
Design of a higher harmonic RF system for the Advanced Light Source
Byrd, J M; De Santis, S; Kosta, S; Lo, C C; Plate, D; Rimmer, R A; Franks, M
2000-01-01
We report on the design and fabrication of a third harmonic radiofrequency (RF) system for the Advanced Light Source (ALS) to be used for lengthening the bunch and increasing the Touschek-dominated beam lifetime. We plan to install five single-cell 1.5 GHz copper RF cavities in one-half of an ALS straight section with a predicted increase in the lifetime by a factor of 3. Each RF cell is designed to sustain a maximum voltage of 125 kV with a power dissipation of 5 kW. We present measurements made on an aluminum cavity model characterizing the RF properties of cavity such as the cavity R/Q and higher-order modes (HOMs). In particular, resonances in the cavity tuners were studied in order to avoid heating of the tuner bellows. Initial measurements of the copper cavities indicate a Q value of 21 000, resulting in a shunt impedance of 1.69 M OMEGA per cell
Energy Technology Data Exchange (ETDEWEB)
Bargallo, E., E-mail: enric.bargallo-font@upc.edu [Fusion Energy Engineering Laboratory (FEEL), Technical University of Catalonia (UPC) Barcelona-Tech, Barcelona (Spain); Giralt, A.; Martinez, G. [Fusion Energy Engineering Laboratory (FEEL), Technical University of Catalonia (UPC) Barcelona-Tech, Barcelona (Spain); Weber, M.; Regidor, D.; Arroyo, J.M. [Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Madrid (Spain); Abal, J.; Dies, J.; Tapia, C.; De Blas, A. [Fusion Energy Engineering Laboratory (FEEL), Technical University of Catalonia (UPC) Barcelona-Tech, Barcelona (Spain); Mendez, P.; Ibarra, A.; Molla, J. [Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Madrid (Spain)
2013-10-15
Highlights: ► Current RF system design based on tetrodes chains is evaluated. ► Alternative solid state power amplifiers RF system design is analyzed. ► Both designs are compared in terms of availability, logistics and cost. ► It is concluded that solid state option presents relevant improvements. -- Abstract: The current design of the radio frequency (RF) power system for the International Fusion Materials Irradiation Facility (IFMIF) is based upon tetrodes technology. Due to the improvement in the solid state amplifiers technology, the possibility of using this option for IFMIF RF system is becoming a very competitive alternative presenting from the beginning several advantages in terms of availability, reliability and logistics. The current design based on RF tetrodes chains leads no room for substantial improvements in terms of availability being the requirement for the RF system hard to achieve. The principal goals of this paper are to use RAMI (Reliability, Availability, Maintainability and Inspectionability) analysis in the solid state amplifier design, and to compare the availability, reliability and logistic performances for both alternatives.
International Nuclear Information System (INIS)
Bargallo, E.; Giralt, A.; Martinez, G.; Weber, M.; Regidor, D.; Arroyo, J.M.; Abal, J.; Dies, J.; Tapia, C.; De Blas, A.; Mendez, P.; Ibarra, A.; Molla, J.
2013-01-01
Highlights: ► Current RF system design based on tetrodes chains is evaluated. ► Alternative solid state power amplifiers RF system design is analyzed. ► Both designs are compared in terms of availability, logistics and cost. ► It is concluded that solid state option presents relevant improvements. -- Abstract: The current design of the radio frequency (RF) power system for the International Fusion Materials Irradiation Facility (IFMIF) is based upon tetrodes technology. Due to the improvement in the solid state amplifiers technology, the possibility of using this option for IFMIF RF system is becoming a very competitive alternative presenting from the beginning several advantages in terms of availability, reliability and logistics. The current design based on RF tetrodes chains leads no room for substantial improvements in terms of availability being the requirement for the RF system hard to achieve. The principal goals of this paper are to use RAMI (Reliability, Availability, Maintainability and Inspectionability) analysis in the solid state amplifier design, and to compare the availability, reliability and logistic performances for both alternatives
The design and development of a multilayer RF circuit card
Ferro, John Francis
1991-01-01
The goal of this project was to design an airborne radio frequency circuit card that was very light weight, occupied a small volume, and operated from 20 Mhz to 1500 Mhz. The circuit card being reported on is called an RF multicoupler, and is one of two cards used in a radio frequency distribution unit (RFD). This unit interfaces a large number of receivers to various antennas. In the past this type of circuitry was done by cascading discrete connectorized RF compo...
Final Report for 'Design calculations for high-space-charge beam-to-RF conversion'
International Nuclear Information System (INIS)
Smithe, David N.
2008-01-01
Accelerator facility upgrades, new accelerator applications, and future design efforts are leading to novel klystron and IOT device concepts, including multiple beam, high-order mode operation, and new geometry configurations of old concepts. At the same time, a new simulation capability, based upon finite-difference 'cut-cell' boundaries, has emerged and is transforming the existing modeling and design capability with unparalleled realism, greater flexibility, and improved accuracy. This same new technology can also be brought to bear on a difficult-to-study aspect of the energy recovery linac (ERL), namely the accurate modeling of the exit beam, and design of the beam dump for optimum energy efficiency. We have developed new capability for design calculations and modeling of a broad class of devices which convert bunched beam kinetic energy to RF energy, including RF sources, as for example, klystrons, gyro-klystrons, IOT's, TWT's, and other devices in which space-charge effects are important. Recent advances in geometry representation now permits very accurate representation of the curved metallic surfaces common to RF sources, resulting in unprecedented simulation accuracy. In the Phase I work, we evaluated and demonstrated the capabilities of the new geometry representation technology as applied to modeling and design of output cavity components of klystron, IOT's, and energy recovery srf cavities. We identified and prioritized which aspects of the design study process to pursue and improve in Phase II. The development and use of the new accurate geometry modeling technology on RF sources for DOE accelerators will help spark a new generational modeling and design capability, free from many of the constraints and inaccuracy associated with the previous generation of 'stair-step' geometry modeling tools. This new capability is ultimately expected to impact all fields with high power RF sources, including DOE fusion research, communications, radar and other
An algorithm for the design and tuning of RF accelerating structures with variable cell lengths
Lal, Shankar; Pant, K. K.
2018-05-01
An algorithm is proposed for the design of a π mode standing wave buncher structure with variable cell lengths. It employs a two-parameter, multi-step approach for the design of the structure with desired resonant frequency and field flatness. The algorithm, along with analytical scaling laws for the design of the RF power coupling slot, makes it possible to accurately design the structure employing a freely available electromagnetic code like SUPERFISH. To compensate for machining errors, a tuning method has been devised to achieve desired RF parameters for the structure, which has been qualified by the successful tuning of a 7-cell buncher to π mode frequency of 2856 MHz with field flatness algorithm and tuning method have demonstrated the feasibility of developing an S-band accelerating structure for desired RF parameters with a relatively relaxed machining tolerance of ∼ 25 μm. This paper discusses the algorithm for the design and tuning of an RF accelerating structure with variable cell lengths.
Design of a β=0.175 2-gap spoke resonator
International Nuclear Information System (INIS)
Krawczyk, F.L.; Chan, K.C.D.; Garnett, R.; Gentzlinger, R.; LaFave, R.P.; Kelley, J.P.; Schrage, D.L.; Tajima, T.; Roybal, P.L.
2003-01-01
In this paper, we present the electromagnetic and structural design of a low-β superconducting spoke resonator for a beam-test in the Low Energy Demonstration Accelerator (LEDA). This test is part of the Advanced Accelerator Applications (AAA) project. Recently, the sole use of superconducting resonators from 6.7 MeV on has been approved for this project. The beam test will use the lowest-β resonator from this accelerator design. The choices of the cavity dimensions are driven by its use immediately after the LEDA Radio-Frequency Quadrupole (RFQ). The frequency is 350 MHz, the length corresponds to a geometric β (β g ) of 0.175. Our design approach has been to carry out an integrated RF and mechanical design from the start. The final cavity is well understood in terms of RF and mechanical properties. The RF properties, like Q, R/Q, peak surface fields and acceleration efficiency are very reasonable for such a low-β structure. The design also includes power coupler, vacuum and pick-up ports and their influences. The mechanical design added tuning sensitivities, tuning forces, stiffening schemes and the understanding of stresses under various load conditions. This presentation reflects changes in the coupling port and the beam aperture compared to a previously presented design [1]. (author)
Design of the New Wideband RF System for the CERN PS Booster
Paoluzzi, Mauro; Angoletta, Maria Elena; Arnaudon, Luca; Energico, Salvatore; Findlay, Alan; Haase, Matthias; Jaussi, Michael; Jones, Anthony; Landré, David; Molendijk, John; Quartullo, Danilo; Shaposhnikova, Elena
2016-01-01
For the renovation and upgrade of the CERN PS Booster (PSB) RF systems a development project was launched in 2012. The design, based on a new approach, aimed at replacing the existing tuned, narrowband RF systems with wideband, modular, solid-state driven units. A wide range of issues had to be addressed spanning from RF power production, radiation hardness of solid-state devices, active cancellation of beam-induced voltages, dedicated low-level electronics allowing multi-harmonic operation and beam stability. Following a three-year prototyping and testing campaign and two international reviews, the project endorsement came at the end of year 2015. It foresees the complete removal of present h1, h2 and h10 systems and the deployment of a new one covering all the frequency ranges from 1 MHz to 18 MHz. The four PSB rings will be equipped with 144 identical acceleration cells providing 24 kV total RF voltage per ring. This paper describes the design concepts, the retained solutions, the expected performances and...
Engineering design and fabrication of X-Band components
Filippova, M; Solodko, A; Riddone, G; Syratchev, I
2011-01-01
The CLIC RF frequency has been changed in 2008 from the initial 30 GHz to the European X-band 11.994 GHz permitting beam independent power production using klystrons for the accelerating structure testing. X-band klystron test facilities at 11.424 GHz are operated at SLAC and at KEK [1], and they are used by the CLIC study in the framework of the X-band structure collaboration for testing accelerating structures scaled to that frequency [2]. CERN is currently building a klystron test-stand operating at 11.994 GHz. In addition X-FEL projects at PSI and Sincrotrone Trieste operate at 11.4 GHz. Therefore several RF components accommodating frequencies from 11.424 to 11.994 GHz are required. The engineering design of these RF components (high power and compact loads, bi-directional couplers, X-band splitters, hybrids, phase shifters, variable power attenuators) and the main fabrication processes are presented here.
RF subsystem design for microwave communication receivers
Bickford, W. J.; Brodsky, W. G.
A system review of the RF subsystems of (IFF) transponders, tropscatter receivers and SATCOM receivers is presented. The quantity potential for S-band and X-band IFF transponders establishes a baseline requirement. From this, the feasibility of a common design for these and other receivers is evaluated. Goals are established for a GaAs MMIC (monolithic microwave integrated circuit) device and related local oscillator preselector and self-test components.
Bi-directional triplexer with butterfly MMI coupler using SU-8 polymer waveguides
Mareš, David; Jeřábek, Vítězslav; Prajzler, Václav
2015-01-01
We report about a design of a bi-directional planar optical multiplex/demultiplex filter (triplexer) for the optical part of planar hybrid WDM bi-directional transceiver in fiber-to-the-home (FTTH) PON applications. The triplex lightwave circuit is based on the Epoxy Novolak Resin SU-8 waveguides on the silica-on-silicon substrate with Polymethylmethacrylate cladding layer. The triplexer is comprised of a linear butterfly concept of multimode interference (MMI) coupler separating downstream optical signals of 1490 nm and 1550 nm. For the upstream channel of 1310 nm, an additional directional coupler (DC) is used to add optical signal of 1310 nm propagating in opposite direction. The optical triplexer was designed and optimized using beam propagation method. The insertion losses, crosstalk attenuation, and extinction ratio for all three inputs/outputs were investigated. The intended triplexer was designed using the parameters of the separated DC and MMI filter to approximate the idealized direct connection of both devices.
Ultra-compact silicon nitride grating coupler for microscopy systems
Zhu, Yunpeng; Wang, Jie; Xie, Weiqiang; Tian, Bin; Li, Yanlu; Brainis, Edouard; Jiao, Yuqing; Van Thourhout, Dries
2017-01-01
Grating couplers have been widely used for coupling light between photonic chips and optical fibers. For various quantum-optics and bio-optics experiments, on the other hand, there is a need to achieve good light coupling between photonic chips and microscopy systems. Here, we propose an ultra-compact silicon nitride (SiN) grating coupler optimized for coupling light from a waveguide to a microscopy system. The grating coupler is about 4 by 2 mu m(2) in size and a 116 nm 1 dB bandwidth can be...
Comparison of sound transmission in human ears and coupler loaded by audiometric earphones
DEFF Research Database (Denmark)
Ciric, Dejan; Hammershøi, Dorte
2005-01-01
in the coupler, but since the "ear canal entrance" is not well-defined for the coupler, the mentioned measurements were done at different depths in the coupler. The sound transmission and coupling were described in terms of the pressure division at the entrance of the ear canal and the transmissions in human......, the differences among earphones as well as between human ears and the coupler affect the results of audiometric measurements inducing uncertainty. The influence of these differences is examined by investigating the sound transmission in both human ears and standardized coupler loaded by different audiometric......The thresholds of hearing are usually determined using audiometric earphones. They are calibrated by means of a standardized acoustical coupler. In order to have determined thresholds independent of the earphone type, the coupler should approximate the average human ear closely. Nevertheless...
Design study of a low-emittance high-repetition rate thermionic rf gun
Directory of Open Access Journals (Sweden)
A. Opanasenko
2017-05-01
Full Text Available We propose a novel gridless continuous-wave radiofrequency (rf thermionic gun capable of generating nC ns electron bunches with a rms normalized slice emittance close to the thermal level of 0.3 mm mrad. In order to gate the electron emission, an externally heated thermionic cathode is installed into a stripline-loop conductor. Two high-voltage pulses propagating towards each other in the stripline-loop overlap in the cathode region and create a quasielectrostatic field gating the electron emission. The repetition rate of pulses is variable and can reach up to one MHz with modern solid-state pulsers. The stripline attached to a rf gun cavity wall has with the wall a common aperture that allows the electrons to be injected into the rf cavity for further acceleration. Thanks to this innovative gridless design, simulations suggest that the bunch emittance is approximately at the thermal level after the bunch injection into the cavity provided that the geometry of the cathode and aperture are properly designed. Specifically, a concave cathode is adopted to imprint an Ƨ-shaped distribution onto the beam transverse phase-space to compensate for an S-shaped beam distribution created by the spherical aberration of the aperture-cavity region. In order to compensate for the energy spread caused by rf fields of the rf gun cavity, a 3rd harmonic cavity is used. A detailed study of the electrodynamics of the stripline and rf gun cavity as well as the beam optics and bunch dynamics are presented.
Serpico, C.; Grudiev, A.; Vescovo, R.
2016-10-01
Free-electron lasers represent a new and exciting class of coherent optical sources possessing broad wavelength tunability and excellent optical-beam quality. The FERMI seeded free-electron laser (FEL), located at the Elettra laboratory in Trieste, is driven by a 200 m long, S-band linac: the high energy part of the linac is equipped with 6 m long backward traveling wave (BTW) structures. The structures have small iris radius and a nose cone geometry which allows for high gradient operation. Development of new high-gradient, S-band accelerating structures for the replacement of the existing BTWs is under consideration. This paper investigates two possible solutions for the RF power couplers suitable for a linac driven FEL which require reduced wakefields effects, high operating gradient and very high reliability. The first part of the manuscript focuses on the reduction of residual field asymmetries, while in the second analyzes RF performances, the peak surface fields and the expected breakdown rate. In the conclusion, two solutions are compared and pros and cons are highlighted.
Energy Technology Data Exchange (ETDEWEB)
Serpico, C., E-mail: claudio.serpico@elettra.eu [Elettra - Sincrotrone Trieste, Trieste (Italy); Grudiev, A. [CERN, Geneva (Switzerland); Vescovo, R. [University of Trieste, Trieste (Italy)
2016-10-11
Free-electron lasers represent a new and exciting class of coherent optical sources possessing broad wavelength tunability and excellent optical-beam quality. The FERMI seeded free-electron laser (FEL), located at the Elettra laboratory in Trieste, is driven by a 200 m long, S-band linac: the high energy part of the linac is equipped with 6 m long backward traveling wave (BTW) structures. The structures have small iris radius and a nose cone geometry which allows for high gradient operation. Development of new high-gradient, S-band accelerating structures for the replacement of the existing BTWs is under consideration. This paper investigates two possible solutions for the RF power couplers suitable for a linac driven FEL which require reduced wakefields effects, high operating gradient and very high reliability. The first part of the manuscript focuses on the reduction of residual field asymmetries, while in the second analyzes RF performances, the peak surface fields and the expected breakdown rate. In the conclusion, two solutions are compared and pros and cons are highlighted.
Design of rf conditioner cavities
International Nuclear Information System (INIS)
Govil, R.; Rimmer, R.A.; Sessler, A.; Kirk, H.G.
1992-06-01
Theoretical studies are made of radio frequency structures which can be used to condition electron beams so as to greatly reduce the stringent emittance requirements for successful lasing in a free-electron laser. The basic strategy of conditioning calls for modulating an electron beam in the transverse dimension, by a periodic focusing channel, while it traverses a series of rf cavities, each operating in a TM 210 mode. In this paper, we analyze the cavities both analytically and numerically (using MAFIA simulations). We find that when cylindrical symmetry is broken the coupling impedance can be greatly enhanced. We present results showing various performance characteristics as a function of cavity parameters, as well as possible designs for conditioning cavities
DEFF Research Database (Denmark)
Ding, Yunhong; Ye, Feihong; Peucheret, Christophe
2015-01-01
We report the design and fabrication of a compact multi-core fiber fan-in/fan-out using a grating coupler array on the SOI platform. The grating couplers are fully-etched, enabling the whole circuit to be fabricated in a single lithography and etching step. Thanks to the apodized design...... for the grating couplers and the introduction of an aluminum reflective mirror, a highest coupling efficiency of -3.8 dB with 3 dB coupling bandwidth of 48 nm and 1.5 dB bandwidth covering the whole C band, together with crosstalk lower than -32 dB are demonstrated. (C)2015 Optical Society of America...
Experimental Validation of Topology Optimization for RF MEMS Capacitive Switch Design
DEFF Research Database (Denmark)
Philippine, Mandy Axelle; Zareie, Hosein; Sigmund, Ole
2013-01-01
In this paper, we present 30 distinct RF MEMS capacitive switch designs that are the product of topology optimizations that control key mechanical properties such as stiffness, response to intrinsic stress gradients, and temperature sensitivity. The designs were evaluated with high-accuracy simul...
rf conditioning and breakdown analysis of a traveling wave linac with collinear load cells
Chen, Qushan; Hu, Tongning; Qin, Bin; Xiong, Yongqian; Fan, Kuanjun; Pei, Yuanji
2018-04-01
Huazhong University of Science and Technology (HUST) has built a compact linac-based terahertz free electron laser (THz-FEL) prototype. In order to achieve compact structure, the linac uses collinear load cells instead of conventional output coupler to absorb remanent power at the end of linac. The new designed structure is confronted with rf breakdown problem after a long time conditioning process, so we tried to figure out the breakdown site in the linac. Without transmitted signal, we propose two methods to analyze the breakdown site mainly based on the forward and the reflected power signals. One method focuses on the time relationship of the two signals while the other focuses on the amplitude. Both the two methods indicate the breakdown events happened at the end of the linac and more likely in the first or the second load cell.
rf conditioning and breakdown analysis of a traveling wave linac with collinear load cells
Directory of Open Access Journals (Sweden)
Qushan Chen
2018-04-01
Full Text Available Huazhong University of Science and Technology (HUST has built a compact linac-based terahertz free electron laser (THz-FEL prototype. In order to achieve compact structure, the linac uses collinear load cells instead of conventional output coupler to absorb remanent power at the end of linac. The new designed structure is confronted with rf breakdown problem after a long time conditioning process, so we tried to figure out the breakdown site in the linac. Without transmitted signal, we propose two methods to analyze the breakdown site mainly based on the forward and the reflected power signals. One method focuses on the time relationship of the two signals while the other focuses on the amplitude. Both the two methods indicate the breakdown events happened at the end of the linac and more likely in the first or the second load cell.
Inexpensive 3dB coupler for POF communication by injection-molding production
Haupt, M.; Fischer, U. H. P.
2011-01-01
POFs (polymer optical fibers) gradually replace traditional communication media such as copper and glass within short distance communication systems. Primarily, this is due to their cost-effectiveness and easy handling. POFs are used in various fields of optical communication, e.g. the automotive sector or in-house communication. So far, however, only a few key components for a POF communication network are available. Even basic components, such as splices and couplers, are fabricated manually. Therefore, these circumstances result in high costs and fluctuations in components' performance. Available couplers have high insertion losses due to their manufacturing method. This can only be compensated by higher power budgets. In order to produce couplers with higher performances new fabrication methods are indispensable. A cheap and effective way to produce couplers for POF communication systems is injection molding. The paper gives an overview of couplers available on market, compares their performances, and shows a way to produce couplers by means of injection molding.
International Nuclear Information System (INIS)
Sakai, Hiroshi; Umemori, Kensei; Sakanaka, Shogo; Takahashi, Takeshi; Furuya, Takaaki; Shinoe, Kenji; Ishii, Atsushi; Nakamura, Norio; Sawamura, Masaru
2009-01-01
We started to develop an input coupler for a 1.3 GHz ERL superconducting cavity. Required input power is about 20 kW for the cavity acceleration field of 20 MV/m and the beam current of 100 mA in energy recovery operation. The input coupler is designed based on the STF-BL input coupler and some modifications are applied to the design for the CW 20 kW power operation. We fabricated input coupler components such as ceramic windows and bellows and carried out the high-power test of the components by using a 30 kW IOT power source and a test stand constructed for the highpower test. In this report, we mainly describe the results of the high-power test of ceramic window and bellows. (author)
Zeno effect and switching of solitons in nonlinear couplers
DEFF Research Database (Denmark)
Abdullaev, F Kh; Konotop, V V; Ögren, Magnus
2011-01-01
The Zeno effect is investigated for soliton type pulses in a nonlinear directional coupler with dissipation. The effect consists in increase of the coupler transparency with increase of the dissipative losses in one of the arms. It is shown that localized dissipation can lead to switching...
Beam physics design strategy for a high-current rf linac
Energy Technology Data Exchange (ETDEWEB)
Reiser, M. [Univ. of Maryland, College Park, MD (United States)
1995-10-01
The high average beam power of an rf linac system for transmutation of nuclear waste puts very stringent requirements on beam quality and beam control. Fractional beam losses along the accelerator must be kept at extremely low levels to assure {open_quotes}hands-on{close_quotes} maintenance. Hence, halo formation and large-amplitude tails in the particle distribution due to beam mismatch and equipartitioning effects must be avoided. This implies that the beam should ideally be in near-perfect thermal equilibrium from injection to full energy - in contrast to existing rf linacs in which the transverse temperature, T {sub {perpendicular}}, is higher than the longitudinal temperature, T{sub {parallel}}. The physics and parameter scaling for such a system will be reviewed using the results of recent work on high-intensity bunched beams. A design strategy for a high-current rf linac with equilibrated beam will be proposed.
Directional couplers using long-range surface plasmon polariton waveguides
DEFF Research Database (Denmark)
Boltasseva, Alexandra; Bozhevolnyi, Sergey I.
2006-01-01
14-nm-thick stripes and a wavelength of 1550 urn, LR-SPP propagation loss is determined for the stripe widths varying from 2 to 12 mu m and is found to be similar to 7 and 5 dB/cm for 10- and 4-mu m-wide stripes, respectively. For the directional couplers based on 14-nm-thick and 8-mu m-wide gold...... stripes and a wavelength of 1570 nm, the coupling lengths of 4.1, 1.9, and 0.8 mm are found for the respective waveguide separations of 8, 4, and 0 mu m. We model the LR-SPP-based directional couplers using the effective-refractive-index method and obtain a good agreement with the experimental results....... The transmission spectra of LR-SPP-based directional couplers are presented demonstrating an efficient (similar to 30 dB) separation of different telecom wavelength bands. Various possibilities for dynamic control of wavelength division/multiplexing with LRSPP-based directional couplers that utilize the thermo...
High efficiency grating couplers based on shared process with CMOS MOSFETs
International Nuclear Information System (INIS)
Qiu Chao; Sheng Zhen; Wu Ai-Min; Wang Xi; Zou Shi-Chang; Gan Fu-Wan; Li Le; Albert Pang
2013-01-01
Grating couplers are widely investigated as coupling interfaces between silicon-on-insulator waveguides and optical fibers. In this work, a high-efficiency and complementary metal—oxide—semiconductor (CMOS) process compatible grating coupler is proposed. The poly-Si layer used as a gate in the CMOS metal—oxide—semiconductor field effect transistor (MOSFET) is combined with a normal fully etched grating coupler, which greatly enhances its coupling efficiency. With optimal structure parameters, a coupling efficiency can reach as high as ∼ 70% at a wavelength of 1550 nm as indicated by simulation. From the angle of fabrication, all masks and etching steps are shared between MOSFETs and grating couplers, thereby making the high performance grating couplers easily integrated with CMOS circuits. Fabrication errors such as alignment shift are also simulated, showing that the device is quite tolerant in fabrication. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Broadband photonic crystal fiber coupler with polarization selection of coupling ratio
Jaroszewicz, Leszek R.; Stasiewicz, Karol A.; Marć, Paweł; Szymański, Michał
2010-09-01
In the paper a new broadband photonic crystal fiber coupler is presented. The proper application of the biconical taper technology has been used for manufacturing the coupler without air holes collapse in LMA10 fiber (NKT Photonics Crystal). This coupler, operates in the weakly coupling condition, protects coupling operation in range from 900 nm to 1700 nm. The coupling ratio between output arms is depending on wavelength and can be tuning by selection the proper input state of polarization. It gives opportunity to use the broadband crystal fiber coupler in many applications in which it is necessary to tune a coupling between output arms during the measurement.
Topology optimization of grating couplers for the efficient excitation of surface plasmons
DEFF Research Database (Denmark)
Andkjær, Jacob Anders; Sigmund, Ole; Nishiwaki, Shinji
2010-01-01
We propose a methodology for a systematic design of grating couplers for efficient excitation of surface plasmons at metal-dielectric interfaces. The methodology is based on a two-dimensional topology optimization formulation based on the H-polarized scalar Helmholtz equation and finite-element m...
Finite-Element 2D and 3D PIC Modeling of RF Devices with Applications to Multipacting
De Ford, John F; Petillo, John
2005-01-01
Multipacting currently limits the performance of many high power radio-frequency (RF) devices, particularly couplers and windows. Models have helped researchers understand and mitigate this problem in 2D structures, but useful multipacting models for complicated 3D structures are still a challenge. A combination of three recent technologies that have been developed in the Analyst and MICHELLE codes begin to address this challenge: high-order adaptive finite-element RF field calculations, advanced particle tracking on unstructured grids, and comprehensive secondary emission models. Analyst employs high-order adaptive finite-element methods to accurately compute driven RF fields and eigenmodes in complex geometries, particularly near edges, corners, and curved surfaces. To perform a multipacting analysis, we use the mesh and fields from Analyst in a modified version of the self-consistent, finite-element gun code MICHELLE. MICHELLE has both a fast, accurate, and reliable particle tracker for unstructured grids ...
Unconsumed precursors and couplers after formation of oxidative hair dyes
DEFF Research Database (Denmark)
Rastogi, Suresh Chandra; Søsted, Heidi; Johansen, Jeanne Duus
2006-01-01
Contact allergy to hair dye ingredients, especially precursors and couplers, is a well-known entity among consumers having hair colouring done at home or at a hairdresser. The aim of the present investigation was to estimate consumer exposure to some selected precursors (p-phenylenediamine, toluene......-2,5-diamine) and couplers (3-aminophenol, 4-aminophenol, resorcinol) of oxidative hair dyes during and after hair dyeing. Concentrations of unconsumed precursors and couplers in 8 hair dye formulations for non-professional use were investigated, under the conditions reflecting hair dyeing. Oxidative...... hair dye formation in the absence of hair was investigated using 6 products, and 2 products were used for experimental hair dyeing. In both presence and absence of hair, significant amounts of unconsumed precursors and couplers remained in the hair dye formulations after final colour development. Thus...
Design approach for the development of a cryomodule for compact crab cavities for Hi-Lumi LHC
Pattalwar, Shrikant; Jones, Thomas; Templeton, Niklas; Goudket, Philippe; McIntosh, Peter; Wheelhouse, Alan; Burt, Graeme; Hall, Ben; Wright, Loren; Peterson, Tom
2014-01-01
A prototype Superconducting RF (SRF) cryomodule, comprising multiple compact crab cavities is foreseen to realise a local crab crossing scheme for the "Hi-Lumi LHC", a project launched by CERN to increase the luminosity performance of LHC. A cryomodule with two cavities will be initially installed and tested on the SPS drive accelerator at CERN to evaluate performance with high-intensity proton beams. A series of boundary conditions influence the design of the cryomodule prototype, arising from; the complexity of the cavity design, the requirement for multiple RF couplers, the close proximity to the second LHC beam pipe and the tight space constraints in the SPS and LHC tunnels. As a result, the design of the helium vessel and the cryomodule has become extremely challenging. This paper assesses some of the critical cryogenic and engineering design requirements and describes an optimised cryomodule solution for the evaluation tests on SPS.
Benedikovic, Daniel; Alonso-Ramos, Carlos; Cheben, Pavel; Schmid, Jens H; Wang, Shurui; Xu, Dan-Xia; Lapointe, Jean; Janz, Siegfried; Halir, Robert; Ortega-Moñux, Alejandro; Wangüemert-Pérez, J Gonzalo; Molina-Fernández, Iñigo; Fédéli, Jean-Marc; Vivien, Laurent; Dado, Milan
2015-09-15
We present the first experimental demonstration of a new fiber-chip grating coupler concept that exploits the blazing effect by interleaving the standard full (220 nm) and shallow etch (70 nm) trenches in a 220 nm thick silicon layer. The high directionality is obtained by controlling the separation between the deep and shallow trenches to achieve constructive interference in the upward direction and destructive interference toward the silicon substrate. Utilizing this concept, the grating directionality can be maximized independent of the bottom oxide thickness. The coupler also includes a subwavelength-engineered index-matching region, designed to reduce the reflectivity at the interface between the injection waveguide and the grating. We report a measured fiber-chip coupling efficiency of -1.3 dB, the highest coupling efficiency achieved to date for a surface grating coupler in a 220 nm silicon-on-insulator platform fabricated in a conventional dual-etch process without high-index overlays or bottom mirrors.
Ultra-low loss nano-taper coupler for Silicon-on-Insulator ridge waveguide
DEFF Research Database (Denmark)
Pu, Minhao; Liu, Liu; Ou, Haiyan
2010-01-01
A nano-taper coupler is optimized specially for the transverse-magnetic mode for interfacing light between a silicon-on-insulator ridge waveguide and a single-mode fiber. An ultra-low coupling loss of ~0.36dB is achieved for the nano-taper coupler.......A nano-taper coupler is optimized specially for the transverse-magnetic mode for interfacing light between a silicon-on-insulator ridge waveguide and a single-mode fiber. An ultra-low coupling loss of ~0.36dB is achieved for the nano-taper coupler....
International Nuclear Information System (INIS)
Henestroza, E.; Yu, S.S.; Li, H.
1995-04-01
An inductively detuned traveling wave cavity for the Relativistic Klystron Two Beam Accelerator expected to extract high RF power at 11. 424 GHz for the 1 TeV Center of Mass Next Linear Collider has been designed. Longitudinal beam dynamics studies led to the following requirements on cavity design: (a) Extraction of 360 MW of RF power with RF component of the current being 1.15 kAmps at 11.424 GHz, (b) Inductively detuned traveling wave cavity with wave phase velocity equal to 4/3 the speed of light, (c) Output cavity with appropriate Q ext and eigenfrequency for proper matching. Furthermore, transverse beam dynamics require low shunt impedances to avoid the beam break-up instability. We describe the design effort to meet these criteria based on frequency-domain and time-domain computations using 2D- and 3D- electromagnetic codes
Design of resonant converter based DC power supply for RF amplifier
International Nuclear Information System (INIS)
Mohan, Kartik; Suthar, Gajendra; Dalicha, Hrushikesh; Agarwal, Rohit; Trivedi, R.G.; Mukherjee, Aparajita
2017-01-01
ITER require 20 MW of RF power to a large variety of plasmas in the Ion Cyclotron frequency range for heating and driving plasma current. Nine RF sources of 2.5MW RF power level each collectively will accomplish the above requirement. Each RF source consists of SSPA, driver and end stage, above which driver and end stage amplifier are tube (Tetrode/Diacrode) based which requires auxiliary DC power source viz. filament, screen grid and control grid DC power supply. DC power supply has some stringent requirements like low stored energy, fast turn off, and low ripple value, etc. This paper will focus only on Zero Current Switching (ZCS) resonant converter based buck converter. This can serve the purpose of control grid and screen grid DC power supply for above requirement. IGBT switch will be used at 20 kHz so as to lower the filter requirement hence low stored energy and ripple in the output voltage. ZCS operation will also assist us in reducing EMI/EMC effect. Design of resonant tank circuit is important aspect of the converter as it forms the backbone of the complete system and basis of selection of other important parameters as well hence mathematical model analysis with the help of circuit equations for various modes have been shown as a part of selection criteria. Peak current through the switch, duty cycle, switching frequency will be the design parameters for selecting resonant tank circuit
Designing RF control subsystems using the VXIbus standard
International Nuclear Information System (INIS)
Stepp, J.D.; Vong, F.C.; Bridges, J.F.
1993-01-01
Various components are being designed to control the RF system of the 7-GeV Advanced Photon Source (APS). The associated control electronics (phase shifters, amplitude modulators, phase detectors, automatic tuning control, and local feedback control) are designed as modular cards with multiple channels for ease of replacement as well as for compact design. Various specifications of the VXIbus are listed and the method used to simplify the design of the control subsystem is shown. A commercial VXI interface board was used to speed the design cycle. Required manpower and actual task times are included. A discussion of the computer architecture and software development of the device drivers which allowed computer control from a VME processor located in a remote crate operating under the Experimental Physics and Industrial Controls Software (EPICS) program is also presented
RF control hardware design for CYCIAE-100 cyclotron
Energy Technology Data Exchange (ETDEWEB)
Yin, Zhiguo, E-mail: bitbearAT@hotmail.com; Fu, Xiaoliang; Ji, Bin; Zhao, Zhenlu; Zhang, Tianjue; Li, Pengzhan; Wei, Junyi; Xing, Jiansheng; Wang, Chuan
2015-11-21
The Beijing Radioactive Ion-beam Facility project is being constructed by BRIF division of China Institute of Atomic Energy. In this project, a 100 MeV high intensity compact proton cyclotron is built for multiple applications. The first successful beam extraction of CYCIAE-100 cyclotron was done in the middle of 2014. The extracted proton beam energy is 100 MeV and the beam current is more than 20 μA. The RF system of the CYCIAE-100 cyclotron includes two half-wavelength cavities, two 100 kW tetrode amplifiers and power transmission line systems (all above are independent from each other) and two sets of Low Level RF control crates. Each set of LLRF control includes an amplitude control unit, a tuning control unit, a phase control unit, a local Digital Signal Process control unit and an Advanced RISC Machines based EPICS IOC unit. These two identical LLRF control crates share one common reference clock and take advantages of modern digital technologies (e.g. DSP and Direct Digital Synthesizer) to achieve closed loop voltage and phase regulations of the dee-voltage. In the beam commission, the measured dee-voltage stability of RF system is better than 0.1% and phase stability is better than 0.03°. The hardware design of the LLRF system will be reviewed in this paper.
Nonclassical properties of a contradirectional nonlinear optical coupler
Energy Technology Data Exchange (ETDEWEB)
Thapliyal, Kishore [Jaypee Institute of Information Technology, A-10, Sector-62, Noida, UP-201307 (India); Pathak, Anirban, E-mail: anirban.pathak@gmail.com [Jaypee Institute of Information Technology, A-10, Sector-62, Noida, UP-201307 (India); RCPTM, Joint Laboratory of Optics of Palacky University and Institute of Physics of Academy of Science of the Czech Republic, Faculty of Science, Palacky University, 17. listopadu 12, 771 46 Olomouc (Czech Republic); Sen, Biswajit [Department of Physics, Vidyasagar Teachers' Training College, Midnapore 721101 (India); Perřina, Jan [RCPTM, Joint Laboratory of Optics of Palacky University and Institute of Physics of Academy of Science of the Czech Republic, Faculty of Science, Palacky University, 17. listopadu 12, 771 46 Olomouc (Czech Republic); Department of Optics, Palacky University, 17. listopadu 12, 771 46 Olomouc (Czech Republic)
2014-10-24
We investigate the nonclassical properties of output fields propagated through a contradirectional asymmetric nonlinear optical coupler consisting of a linear waveguide and a nonlinear (quadratic) waveguide operated by second harmonic generation. In contrast to the earlier results, all the initial fields are considered weak and a completely quantum-mechanical model is used here to describe the system. Perturbative solutions of Heisenberg's equations of motion for various field modes are obtained using Sen–Mandal technique. Obtained solutions are subsequently used to show the existence of single-mode and intermodal squeezing, single-mode and intermodal antibunching, two-mode and multi-mode entanglement in the output of contradirectional asymmetric nonlinear optical coupler. Further, existence of higher order nonclassicality is also established by showing the existence of higher order antibunching, higher order squeezing and higher order entanglement. Variation of observed nonclassical characters with different coupling constants and phase mismatch is discussed. - Highlights: • Nonclassicalities in fields propagating through a directional coupler is studied. • Completely quantum-mechanical description of the coupler is provided. • Analytic solutions of Heisenberg equations of motion for various modes are obtained. • Existence of lower order and higher order entanglement is shown. • Variation of nonclassicalities with phase-mismatch and coupling constants is studied.
Magnetic field sensor based on cascaded microfiber coupler with magnetic fluid
Energy Technology Data Exchange (ETDEWEB)
Mao, Lianmin; Su, Delong; Wang, Zhaofang [College of Science, University of Shanghai for Science and Technology, Shanghai 200093 (China); Pu, Shengli, E-mail: shlpu@usst.edu.cn [College of Science, University of Shanghai for Science and Technology, Shanghai 200093 (China); Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093 (China); Zeng, Xianglong [The Key Lab of Specialty Fiber Optics and Optical Access Network, Shanghai University, Shanghai 200072 (China); Lahoubi, Mahieddine [Laboratory L.P.S., Department of Physics, Faculty of Sciences, Badji-Mokhtar Annaba University, Annaba 23000 (Algeria)
2016-09-07
A kind of magnetic field sensor based on cascaded microfiber coupler with magnetic fluid is proposed and experimentally demonstrated. The magnetic fluid is utilized as the cladding of the fused regions of the cascaded microfiber coupler. As the interference valley wavelength of the sensing structure is sensitive to the ambient variation, considering the magnetic-field-dependent refractive index of magnetic fluid, the proposed structure is employed for magnetic field sensing. The effective coupling length for each coupling region of the as-fabricated cascaded microfiber coupler is 6031 μm. The achieved sensitivity is 125 pm/Oe, which is about three times larger than that of the previously similar structure based on the single microfiber coupler. Experimental results indicate that the sensing sensitivity can be easily improved by increasing the effective coupling length or cascading more microfiber couplers. The proposed magnetic field sensor is attractive due to its low cost, immunity to electromagnetic interference, as well as high sensitivity, which also has the potentials in other tunable all-fiber photonic devices, such as filter.
International Nuclear Information System (INIS)
Shrivastava, Purushottam; Wanmode, Y.D.; Hannurkar, P.R.
2002-01-01
Development of a 100 MeV CW proton Linac has been planned at CAT. This Linac will be needing CW rf power in the frequency ranges of 350 MHz and 700 MHz for its RFQ and DTL/CCDTL/SFDTL structures respectively. The power to the accelerating structures will be produced by either 1 MW CW or 250 kW CW klystron/inductive output tubes (HOM IOTs). The power needed by respective feed points in the structure is max. 250 kW which will be powered by splitting the power from 1 MW klystron/klystrode into four channels by using a wave-guide system. In case of using 250 kW tubes the power to the structures will be provided directly from each tube. Two types of wave-guide transmission system have been considered, viz WR 2300 for 350 MHz rf needs and WR 1500 for 700 MHz rf needs. The typical wave-guide system has been designed using the 1 MW CW klystron followed by wave-guide filter, dual directional coupler, high-power circulator, three 3 dB magic TEE power dividers to split the main channel into four equal channels of 250 kW each. Each individual channel has dual directional couplers, flexible wave-guide sections and high power ceramic vacuum window. The circulator and each power divider is terminated into the isolated ports by high power CW loads. Out of the four channels three channels have phase shifters. Present paper describes the technological aspects and design specifications-considerations for these stringent requirements. (author)
Design of the 3.7 GHz, 500 kW CW circulator for the LHCD system of the SST-1 tokamak
Energy Technology Data Exchange (ETDEWEB)
Dixit, Harish V., E-mail: hvdixit48@yahoo.com [Veermata Jijabai Technological Institute, Mumbai, Maharashtra 400019 (India); Jadhav, Aviraj R. [Veermata Jijabai Technological Institute, Mumbai, Maharashtra 400019 (India); Jain, Yogesh M. [Institute for Plasma Research, Gandhinagar, Gujarat 382428 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094 (India); Cheeran, Alice N. [Veermata Jijabai Technological Institute, Mumbai, Maharashtra 400019 (India); Gupta, Vikas [Vidyavardhini' s College of Engineering and Technology, Vasai, Maharashtra 401202 (India); Sharma, P.K. [Institute for Plasma Research, Gandhinagar, Gujarat 382428 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094 (India)
2017-06-15
Highlights: • Design of a 500 kW CW circulator for LHCD system at 3.7 GHz. • Mechanism for thermal management of ferrite tile. • Scheme for uniform magnetisation of the ferrite tiles. • Design of high CW power CW quadrature and 180 ° hybrid coupler. - Abstract: Circulators are used in high power microwave systems to protect the vacuum source against reflection. The Lower Hybrid Current Drive (LHCD) system of SST-1 tokamak commissioned at IPR, Gandhinagar in India comprises of four high power circulators to protect klystrons (supplying 500 kW CW each at 3.7 GHz) which power the system. This paper presents the design of a Differential Phase Shift Circulator (DPSC) capable of handling 500 kW CW power at 3.7 GHz so that four circulators can be used to protect the four available klystrons. As the DPSC is composed by three main components, viz., magic tee, ferrite phase shifter and 3 dB hybrid coupler, the designing of each of the proposed components is described. The design of these components is carried out factoring various multiphysics aspects of RF, heating due to high CW power and magnetic field requirement of the ferrite phase shifter. The primary objective of this paper is to present the complete RF, magnetic and thermal design of a high CW power circulator. All the simulations have been carried out in COMSOL Multiphysics. The designed circulator exhibits an insertion loss of 0.13 dB with a worst case VSWR of 1.08:1. The total length of the circulator is 3 m.
Mechanical design of a RF electron gun
International Nuclear Information System (INIS)
Woodle, M.H.; Batchelor, K.; Sheehan, J.
1989-01-01
Brookhaven National Laboratory is building an Accelerator Test Facility at which we plan to study laser acceleration of electrons, inverse free electron lasers and the production of X-rays by non-linear Compton scattering. The facility contains an electron gun, linac, lasers and ancillary systems which will enable the production of 6 ps duration pulses of 50-100 MeV electrons. The electron source is an one and one half cell RF Electron gun which utilizes either a thermionic or photoemissive cathode to produce 5 MeV electrons. This paper discusses how gun mechanical design considerations such as material, vacuum maintenance, surface finish, fabrication methods, cavity tuning, and cathode replacement were reconciled to arrive at the final design. 9 refs., 2 figs., 2 tabs
Mechanical design of a rf electron gun
International Nuclear Information System (INIS)
Woodle, M.H.; Batchelor, K.; Sheehan, J.
1988-01-01
Brookhaven National Laboratory is building an Accelerator Test Facility at which we plan to study laser acceleration of electrons inverse free electron lasers and the production of X-rays by non- linear Compton scattering. The facility contains an electron gun, linac, lasers and ancillary systems which will enable the production of 6 ps duration pulses of 50--100 MeV electrons. The electron source is an one and one half cell RF Electron gun which utilizes either a thermionic or photoemissive cathode to produce 5 MeV electrons. This paper discusses how gun mechanical design considerations such as material, vacuum maintenance, surface finish, fabrication methods, cavity tuning, and cathode replacement were reconciled to arrive at the final design. 9 refs., 2 figs., 2 tabs
Energy Technology Data Exchange (ETDEWEB)
Kim, Sun Ho; Jeong, Seung Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Hyun Woo; Lee, Byung Je [Kwang Woon University, Chuncheon (Korea, Republic of); Jo, Jong Gab; Lee, Hyun Young; Hwang, Yong Seok [Seoul National University, Seoul (Korea, Republic of)
2015-10-15
Continuous current drive is one of the key issues for tokamak to be a commercial fusion reactor. As a part of new and efficient current drive concept research by using a Lower Hybrid Fast Wave (LHFW), the experimental study is planned on Versatile Experiment Spherical Torus (VEST) and a RF system is being developed in collaboration with Kwang Woon University (KWU), Korea Accelerator Plasma Research Association (KAPRA) and Seoul National University (SNU). The LHFW RF system includes UHF band klystron, inter-digital antenna, RF diagnostics and power transmission sub components such as circulator, DC breaker, vacuum feed-thru. The design and preparation status of the RF system will be presented in the meeting in detail. A RF system has been designed and prepared for the experimental study of efficient current drive by using Lower Hybrid Fast Wave. Overall LHFW RF system including diagnostics is designed to deliver about 10 kW in UHF band. And the key hardware components including klystron and antenna are being prepared and designed through the collaboration with KWU, KAPRA and SNU.
The design of a 3 GHz thermionic RF-gun and energy filter for MAX-lab
Anderberg, B; Demirkan, M; Eriksson, M; Malmgren, L; Werin, S
2002-01-01
A new pre-injector has been designed for the MAX-laboratory. It consists of an RF-gun and a magnetic energy filter. The newly designed RF-gun geometry will be operated at 3 GHz in the thermionic mode using a BaO cathode. The pre-injector will provide a 2.3 MeV electron beam in 3 ps micro pulses to a new injector system currently under construction.
A conceptual design of the RF system for the NSP high intensity proton accelerator at JAERI
International Nuclear Information System (INIS)
Chishiro, Etsuji; Kusano, Joichi; Mizumoto, Motoharu; Touchi, Yutaka; Kaneko, Hiroshi; Takado, Hiroshi; Sawada, Junichi
1999-03-01
JAERI has been proposing the Neutron Science Project which aims at exploring the fields of basic science and nuclear technology using a high power spallation neutron source. The neutron source will be driven by a high intensity linear accelerator with an energy of 1.5 GeV and an average beam current of 5.33 mA and beam power of 8 MW. The RF system for the accelerator consists of a high-energy accelerator part and a low energy accelerator part. The maximum RF power requirements at the high and low energy accelerator parts are 25 MW and 8.3 MW, respectively. In this report, we describe the conceptual design of the RF system. In the low energy accelerator part, we estimated the requirement for the high-power amplifier tube and made the basis design for RF components. In the high energy accelerator part, we studied the effect of tuning errors, Lorentz forces and microphonics in the superconducting cavity. We calculated the klystron efficiency and supply power in the arrangement of where one klystron distributes the RF power to four cavities. We also considered an IOT RF system. Finally, we describe the electrical capacity and quantity of cooling water in the RF system. (author)
Design and construction of the advanced photon source 352-MHz rf system switching control
International Nuclear Information System (INIS)
Horan, D.; Solita, L.; Reigle, D.; Dimonte, N.
1997-01-01
A switching control system has been designed and built to provide the capability of rapidly switching the waveguide and low-level cabling between different klystrons to operate the Advanced Photon Source storage ring in the event of a failure of a klystron system or to perform necessary repairs and preventative maintenance. The twelve possible modes of operation allow for complete redundancy of the booster synchrotron rf system and either a maximum of two storage ring rf systems to be completely off-line or one system to be used as a power source for an rf test stand. A programmable controller is used to send commands to intermediate control panels which interface to WR2300 waveguide switches and phase shifters, rf cavity interlock and low-level rf distribution systems, and klystron power supply controls for rapid reconfiguration of the rf systems in response to a mode-selection command. Mode selection is a local manual operation using a keyswitch arrangement which prevents more than one mode from being selected at a time. The programmable controller also monitors for hardware malfunction and guards against open-quotes hot-switchingclose quotes of the rf systems. The rf switching controls system is monitored via the Experimental Physics and Industrial Control System (EPICS) for remote system status check
Design aspects of 13.56MHz, 1kW, CW-RF oscillator for plasma production
International Nuclear Information System (INIS)
Kumar, Sunil; Kadia, Bhavesh; Singh, Raj; Varia, Atul; Srinivas, Y S S; Kulkarni, S V
2010-01-01
RF produced plasma has many applications in plasma processing and also it is useful in studying the fundamental characteristics of the plasma. A 1KW RF Hartley oscillator is designed and tested at 13.56 MHz. This has been built at RF section of Institute for Plasma Research by using EIMAC (3CX1200A7) triode tube. The RF source is operated in the grounded cathode mode. Triode 3CX1200A7 is operated in class AB and the feedback is Cathode grounded. The tube has sufficient margin in terms of plate dissipation and Grid dissipation that makes it suitable to withstand momentarily load mismatch. To optimize the RF source along with HVDC power supply many mechanical and electrical aspects have been thought of to enhance the overall quality of the system. This source mainly has three sections (The RF section, HVDC Power supply and soft start Filament Power supply). The system is compact and is housed in a 80 cm x 60 cm x 1800 cm aluminum panel. This paper describes the specifications, design criteria, circuit used, operating parameters of 1KW Oscillator along with HVDC power supply with necessary interlocks, tests conducted and results obtained of this 1 KW grounded grid Hartley Oscillator on 50 ohm dummy load. This system has been tested for 8 hours of continuous operation without any appreciable deterioration of the RF output power.
Low Loss 1×2 Optical Coupler Based on Cosine S-bend with Segmented Waveguides
Yulianti, Ian; Sahmah, Abu; Supa'at, M.; Idrus, Sevia M.; Ridwanto, Muhammad; Al-hetar, Abdulaziz M.
2011-05-01
This paper presents an optimization of 1×2 polymer Y-junction optical coupler. The optimized optical coupler comprises straight polymer waveguide as the input waveguide, tapered waveguide, modified cosine S-bend and linear waveguide. At the branching point, N short waveguides with small width are introduced to reduce evanescent field. At operating wavelength of 1550 nm the excess loss of the coupler is ˜0.18 dB. In term of polarization dependence loss (PDL), the proposed coupler also shows a good performance with PDL value of less than 0.015 dB for wavelength range of 1470 nm-1550 nm. The proposed coupler could reduce excess loss more than 25% compared to conventional Y junction optical coupler.
All-optical switching using a new photonic crystal directional coupler
Directory of Open Access Journals (Sweden)
B. Vakili
2015-07-01
Full Text Available In this paper all-optical switching in a new photonic crystal directional coupler is performed. The structure of the switch consists of a directional coupler and a separate path for a control signal called “control waveguide”. In contrast to the former reported structures in which the directional couplers are made by removing a row of rods entirely, the directional coupler in our optical switch is constructed by two reduced-radius line-defect waveguides separated by the control waveguide. Furthermore, in our case the background material has the nonlinear Kerr property. Therefore, in the structure of this work, no frequency overlap occurs between the control waveguide mode and the directional coupler modes. It is shown that such a condition provides a very good isolation between the control and the probe signals at the output ports. In the control waveguide, nonlinear Kerr effect causes the required refractive index change by the presence of a high power control (pump signal. Even and odd modes of the coupler are investigated by applying the distribution of the refractive index change in the nonlinear region of a super-cell so that a switching length of about 94 µm is obtained at the wavelength of 1.55 µm. Finally, all-optical switching of the 1.55 µm probe signal using a control signal at the wavelength of 1.3 µm, is simulated through the finite-difference time-domain method, where both signals are desirable in optical communication systems. A very high extinction ratio of 67 dB is achieved and the temporal characteristics of the switch are demonstrated.
Ultra-low-loss inverted taper coupler for silicon-on-insulator ridge waveguide
DEFF Research Database (Denmark)
Pu, Minhao; Liu, Liu; Ou, Haiyan
2010-01-01
An ultra-low-loss coupler for interfacing a silicon-on-insulator ridge waveguide and a single-mode fiber in both polarizations is presented. The inverted taper coupler, embedded in a polymer waveguide, is optimized for both the transverse-magnetic and transverse-electric modes through tapering...... the width of the silicon-on-insulator waveguide from 450 nm down to less than 15 nm applying a thermal oxidation process. Two inverted taper couplers are integrated with a 3-mm long silicon-on-insulator ridge waveguide in the fabricated sample. The measured coupling losses of the inverted taper coupler...... for transverse-magnetic and transverse-electric modes are ~0.36 dB and ~0.66 dB per connection, respectively....
Uematsu, Takui; Kitayama, Tetsuya; Ishizaka, Yuhei; Saitoh, Kunimasa
2014-01-01
An ultrabroadband silicon wire polarization beam combiner/splitter (PBCS) based on a wavelength-insensitive coupler is proposed. The proposed PBCS consists of three identical directional couplers and two identical delay lines. We design the PBCS using the 3-D finite element method. Numerical simulations show that the proposed PBCS can achieve the transmittance of more than 90% over a wide wavelength range from 1450 to 1650 nm for both TE and TM polarized modes.
Injector upgrade for the S-DALINAC
Energy Technology Data Exchange (ETDEWEB)
Kuerzeder, Thorsten; Brunken, Marco; Conrad, Jens; Eichhorn, Ralf; Graef, Hans-Dieter; Richter, Achim; Sievers, Sven [Institut fuer Kernphysik, TU Darmstadt (Germany); Ackermann, Wolfgang; Mueller, Wolfgang F.O.; Steiner, Bastian; Weiland, Thomas [Institut fuer Theorie Elektromagnetischer Felder, TU Darmstadt (Germany); Fuerst, Joel [Argonne National Laboratory, Argonne (United States)
2009-07-01
The injector section of the S-DALINAC currently delivers beams of up to 10 MeV w ith a current of up to 60{mu}A. The upgrade aims to increase both parameters to 14 MeV and 150{mu}A in order to allow more demanding experiments. Therefor e, a modified cryostat module equipped with two new cavities is required. Due to an increase in rf power to 2 kW the old coaxial rf input couplers, being design ed for a maximum power of 500 W, have to be replaced by new waveguide couplers. We review the design principles and report on the fabrication of the cavities an d the whole module.
Studying quick coupler efficiency in working attachment system of single-bucket power shovel
Duganova, E. V.; Zagorodniy, N. A.; Solodovnikov, D. N.; Korneyev, A. S.
2018-03-01
A prototype of a quick-disconnect connector (quick coupler) with an unloaded retention mechanism was developed from the analysis of typical quick couplers used as intermediate elements for power shovels of different manufacturers. A method is presented, allowing building a simulation model of the quick coupler prototype as an alternative to physical modeling for further studies.
Near-field probing of photonic crystal directional couplers
DEFF Research Database (Denmark)
Volkov, V. S.; Bozhevolnyi, S. I.; Borel, Peter Ingo
2006-01-01
We report the design, fabrication and characterization of a photonic crystal directional with a size of ~20 x 20 mm2 fabricated in silicon-on-insulator material. Using a scanning near-field optical microscope we demonstrate a high coupling efficiency for TM polarized light at telecom wavelengths....... By comparing the near-field optical images recorded in and after the directional coupler area, the features of light distribution are analyzed. Finally, the scanning near-field optical microscope observations are found to be in agreement with the transmission measurements conducted with the same sample....
Mechanical design considerations of a standing wave s-band accelerator with on-axis couplers
International Nuclear Information System (INIS)
Hodge, S.B.; Funk, L.W.; Schriber, S.O.
1976-01-01
The mechanical design of S-band standing wave accelerator structures with on-axis coupling cells includes material selection, cavity design, segment production, rf tuning and brazing procedures. Pre-assembly tuning operations have been minimized by determining segment dimensions and tolerances so that segments can easily be fabricated in a near-finished condition by a commercial machining firm. Final tuning, if necessary, is easily achieved by removal of material from the cavity wall or drift tube nose. Considerations in choosing brazing procedures were vacuum integrity, resistivity of brazing alloy, joint thickness, alignment of the structure assembly and restriction of grain growth. (author)
A new interlock design for the TESLA RF system
International Nuclear Information System (INIS)
Leich, H.; Kahl, J.; Choroba, S.; Grevsmuehl, T.; Heidbrook, N.
2001-01-01
The RF system for TESLA requires a comprehensive interlock system. Usually interlock systems are organized in a hierarchical way. In order to react to different fault conditions in a fast and flexible manner a nonhierarchical organization seems to be the better solution. At the TESLA Test Facility (TTF) at DESY the authors will install a nonhierarchical interlock system that is based on user designed reprogrammable gate-arrays (FPGA's) which incorporate an embedded microcontroller system. This system could be used later for the TESLA linear collider replacing a strictly hierarchical design
Low insertion loss SOI microring resonator integrated with nano-taper couplers
DEFF Research Database (Denmark)
Pu, Minhao; Frandsen, Lars Hagedorn; Ou, Haiyan
2009-01-01
We demonstrate a microring resonator working at TM mode integrated with nano-taper couplers with 3.6dB total insertion loss. The measured insertion loss of the nano-taper coupler was only 1.3dB for TM mode....
Design of Miniaturized 10dB Wideband Branch Line Coupler Using Dual and T-Shape Transmission Lines
Directory of Open Access Journals (Sweden)
M. Kumar
2018-04-01
Full Text Available This paper presents a design mechanism of miniaturized wideband branch line coupler (BLC with loose coupling of 10 dB. Dual transmission lines are used as a feed network which provides a size reduction of 32% with a fractional bandwidth (FBW of 60% for 10±0.5 dB coupling but return loss performance is found to be poor in the operating band. For further improvement of return loss performance as well as for size reduction of the BLC, a T- shape transmission lines are used instead of series quarter wavelength transmission lines, and hence the overall size reduction of around 44% with FBW of 50.4% is achieved. The return loss and isolation performance is found to be les than 15 dB in the entire operating band (2.5–4.1 GHz with respect to design frequency 3G Hz. The proposed BLC is analyzed, fabricated and tested.
International Nuclear Information System (INIS)
Gao, J.
1993-09-01
Starting from a single resonant rf cavity, disk-loaded travelling (forward or backward) wave accelerating structures' properties are determined by rather simple analytical formulae. They include the coupling coefficient K in the dispersion relation, group velocity v g , shunt impedance R, wake potential W (longitudinal and transverse), the coupling coefficient β of the coupler cavity and the coupler cavity axis shift δ r which is introduced to compensate the asymmetry caused by the coupling aperture. (author) 12 refs., 18 figs
Accurate modeling of complete functional RF blocks: CHAMELEON RF
Janssen, H.H.J.M.; Niehof, J.; Schilders, W.H.A.; Ciuprina, G.; Ioan, D.
2007-01-01
Next-generation nano-scale RF-IC designs have an unprecedented complexity and performance that will inevitably lead to costly re-spins and loss of market opportunities. In order to cope with this, the aim of the European Framework 6 CHAMELEON RF project is to develop methodologies and prototype
All-optical switching in lithium niobate directional couplers with cascaded nonlinearity
Schiek, R.; Baek, Y.; Krijnen, Gijsbertus J.M.; Stegeman, G.I.; Baumann, I.; Sohler, W.
1996-01-01
We report on intensity-dependent switching in lithium niobate directional couplers. Large nonlinear phase shifts that are due to cascading detune the coupling between the coupler branches, which makes all-optical switching possible. Depending on the input intensity, the output could be switched
Optimal Design of Dual-Hop VLC/RF Communication System With Energy Harvesting
Rakia, Tamer
2016-07-28
In this letter, we consider a dual-hop heterogeneous visible light communication (VLC)/radio frequency (RF) communication system to extend the coverage of VLC systems. Besides detecting the information over VLC link, the relay is able to harvest energy from the first-hop VLC link, by extracting the direct current component of the received optical signal, and uses the harvested energy to retransmit the data to a mobile terminal over the second-hop RF link. We investigate the optimal design of the hybrid system in terms of data rate maximization.
High-power RF window design for the PEP-II B Factory
International Nuclear Information System (INIS)
Neubauer, M.; Hodgson, J.; Ng, C.; Schwarz, H.; Skarpaas, K.; Kroll, N.; Rimmer, R.
1994-06-01
We describe the design of RF windows to transmit up to 500 kW CW to the PEP-II 476 MHz cavities. RF analysis of the windows using high-frequency simulation codes are described. These provide information about the power loss distribution in the ceramic and tim matching properties of the structure. Finite-element analyses of the resulting temperature distribution and thermal stresses are presented. Fabrication methods including a proposed scheme to compensate for thermal expansion s are discussed and hardware tests to validate this approach are described. The effects of surface coatings (intentional and otherwise) and the application of air cooling are considered
International Nuclear Information System (INIS)
Allen, M.A.
1988-01-01
In this paper, the author reports on RF power sources for accelerator applications. The approach will be with particular customers in mind. These customers are high energy physicists who use accelerators as experimental tools in the study of the nucleus of the atom, and synchrotron light sources derived from electron or positron storage rings. The author pays close attention to electron- positron linear accelerators since the RF sources have always defined what is possible to achieve with these accelerators. Circular machines, cyclotrons, synchrotrons, etc. have usually not been limited by the RF power available and the machine builders have usually had their RF power source requirements met off the shelf. The main challenge for the RF scientist has been then in the areas of controls. An interesting example of this is in the Conceptual Design Report of the Superconducting Super Collider (SSC) where the RF system is described in six pages of text in a 700-page report. Also, the cost of that RF system is about one-third of a percent of the project's total cost. The RF system is well within the state of the art and no new power sources need to be developed. All the intellectual effort of the system designer would be devoted to the feedback systems necessary to stabilize beams during storage and acceleration, with the main engineering challenges (and costs) being in the superconducting magnet lattice
International Nuclear Information System (INIS)
Lynch, M.T.; Rees, D.; Tallerico, P.; Regan, A.
1996-01-01
To develop and demonstrate the crucial front end of the APT accelerator and some of the critical components for APT, Los Alamos is building a CW proton accelerator (LEDA) to provide 100 mA at up to 40 MeV. LEDA will be installed where the SDI-sponsored Ground Test Accelerator was located. The first accelerating structure for LEDA is a 7-MeV RFQ operating at 350 MHz, followed by several stages of a coupled-cavity Drift Tube Linac (CCDTL) operating at 700 MHz. The first stage of LEDA will go to 12 MeV. Higher energies, up to 40 MeV, come later in the program. Three 1.2-MW CW RF systems will be used to power the RFQ. This paper describes the RF systems being assembled for LEDA, including the 350 and 700-MHz klystrons, the High Voltage Power Supplies, transmitters, RF transport, window/coupler assemblies, and controls. Some of the limitations imposed by the schedule and the building itself are addressed
Raman probes based on optically-poled double-clad fiber and coupler
DEFF Research Database (Denmark)
Brunetti, Anna Chiara; Margulis, Walter; Rottwitt, Karsten
2012-01-01
of a sample of dimethyl sulfoxide (DMSO), when illuminating the waveguide with 1064nm laser light. The Raman signal is collected in the inner cladding, from which it is retrieved with either a bulk dichroic mirror or a double-clad fiber coupler. The coupler allows for a substantial reduction of the fiber......Two fiber Raman probes are presented, one based on an optically-poled double-clad fiber and the second based on an optically-poled double-clad fiber coupler respectively. Optical poling of the core of the fiber allows for the generation of enough 532nm light to perform Raman spectroscopy...
International Nuclear Information System (INIS)
Yoon, Min-Seok; Kwon, Oh-Jang; Kim, Hyun-Joo; Chu, Su-Ho; Kim, Gil-Hwan; Lee, Sang-Bae; Han, Young-Geun
2010-01-01
We developed a broadband optical coupler based on a photonic crystal fiber (PCF), which is very useful for applications to optical coherence tomography (OCT). The PCF-based coupler is fabricated by using a fused biconical tapering (FBT) method. The PCF has six hexagonally-stacked layers of air holes. The PCF-based coupler has a nearly-flat 50/50 coupling ratio in a broad bandwidth range of 800 nm, which is much wider than that previously reported for a PCF-based coupler and a singlemode-fiber-based coupler. The bandwidth and the bandedge wavelength of the broadband coupler are controlled by changing the elongation length. The fabricated broadband optical coupler has great potential for realizing a broadband interferogram with a high resolution in an OCT system.
Distributed grating-assisted coupler for optical all-dielectric electron accelerator
Directory of Open Access Journals (Sweden)
Zhiyu Zhang
2005-07-01
Full Text Available A Bragg waveguide consisting of multiple dielectric layers with alternating index of refraction becomes an excellent option to form electron accelerating structure powered by high power laser sources. It provides confinement of a synchronous speed-of-light mode with extremely low loss. However, laser field cannot be coupled into the structure collinearly with the electron beam. There are three requirements in designing input coupler for a Bragg electron accelerator: side coupling, selective mode excitation, and high coupling efficiency. We present a side-coupling scheme using a distributed grating-assisted coupler to inject the laser power into the waveguide. Side coupling is achieved by a grating with a period on the order of an optical wavelength. The phase matching condition results in resonance coupling thus providing selective mode excitation capability. The coupling efficiency is limited by profile matching between the outgoing beam and the incoming beam, which has normally a Gaussian profile. We demonstrate a nonuniform distributed grating structure generating an outgoing beam with a Gaussian profile, therefore, increasing the coupling efficiency.
Design of a low emittance and high repetition rate S-band photoinjector
Han, Jang-Hui
2014-09-01
As an electron beam injector of X-ray free-electron lasers (FELs), photoinjectors have been developed for the past few decades. Such an injector starting with a photocathode RF gun provides high brightness beams and therefore it is being adopted as an injector of X-ray FELs. In this paper we show how to improve photoinjector performance in terms of emittance and repetition rates by means of injector components optimization, especially with the gun. Transverse emittance at the end of an injector is reduced by optimizing the gun design, gun solenoid position, and accelerating section position. The repetition rate of an injector mainly depends on the gun. It is discussed that a repetition rate of 1 kHz at a normal-conducting S-band photoinjector is feasible by adopting a coaxial RF coupler and improving cooling-water channels surrounding the gun.
Comparative Study of Antenna Designs for RF Energy Harvesting
Directory of Open Access Journals (Sweden)
Sika Shrestha
2013-01-01
Full Text Available In the last few years, several antenna designs of rectenna that meet various objectives have been proposed for use in RF energy harvesting. Among various antennas, microstrip patch antennas are widely used because of their low profile, light weight, and planar structure. Conventional patch antennas are rectangular or circular in shape, but variations in their basic design are made for different purposes. This paper begins with an explanation and discussion of different designs, put forward with an aim of miniaturization, harmonic rejection, and reconfigurability. Finally, microstrip patch structured rectennas are evaluated and compared with an emphasis on the various methods adopted to obtain a compact rectenna, harmonic rejection functionality, and frequency and polarization selectivity.
Direct UV-written broadband directional broadband planar waveguide couplers
DEFF Research Database (Denmark)
Olivero, Massimo; Svalgaard, Mikael
2005-01-01
We report the fabrication of broadband directional couplers by direct UV-writing. The fabrication process is shown to be beneficial, robust and flexible. The components are compact and show superior performance in terms of loss and broadband operation.......We report the fabrication of broadband directional couplers by direct UV-writing. The fabrication process is shown to be beneficial, robust and flexible. The components are compact and show superior performance in terms of loss and broadband operation....
A preliminary design of the collinear dielectric wakefield accelerator
Energy Technology Data Exchange (ETDEWEB)
Zholents, A.; Gai, W.; Doran, S.; Lindberg, R.; Power, J.G.; Strelnikov, N.; Sun, Y.; Trakhtenberg, E.; Vasserman, I. [ANL, Argonne, IL 60439 (United States); Jing, C.; Kanareykin, A.; Li, Y. [Euclid Techlabs LLC, Solon, OH 44139 (United States); Gao, Q. [Tsinghua University, Beijing (China); Shchegolkov, D.Y.; Simakov, E.I. [LANL, Los Alamos, NM 87545 (United States)
2016-09-01
A preliminary design of the multi-meter long collinear dielectric wakefield accelerator that achieves a highly efficient transfer of the drive bunch energy to the wakefields and to the witness bunch is considered. It is made from ~0.5 m long accelerator modules containing a vacuum chamber with dielectric-lined walls, a quadrupole wiggler, an rf coupler, and BPM assembly. The single bunch breakup instability is a major limiting factor for accelerator efficiency, and the BNS damping is applied to obtain the stable multi-meter long propagation of a drive bunch. Numerical simulations using a 6D particle tracking computer code are performed and tolerances to various errors are defined.
Fiber pigtailed thin wall capillary coupler for excitation of microsphere WGM resonator.
Wang, Hanzheng; Lan, Xinwei; Huang, Jie; Yuan, Lei; Kim, Cheol-Woon; Xiao, Hai
2013-07-01
In this paper, we demonstrate a fiber pigtailed thin wall capillary coupler for excitation of Whispering Gallery Modes (WGMs) of microsphere resonators. The coupler is made by fusion-splicing an optical fiber with a capillary tube and consequently etching the capillary wall to a thickness of a few microns. Light is coupled through the peripheral contact between inserted microsphere and the etched capillary wall. The coupling efficiency as a function of the wall thickness was studied experimentally. WGM resonance with a Q-factor of 1.14 × 10(4) was observed using a borosilicate glass microsphere with a diameter of 71 μm. The coupler operates in the reflection mode and provides a robust mechanical support to the microsphere resonator. It is expected that the new coupler may find broad applications in sensors, optical filters and lasers.
International Nuclear Information System (INIS)
Mohania, Praveen; Rajput, Vikas; Baxy, Deodatta; Agrawal, Ankur; Mahawar, Ashish; Adarsh, Kunver; Singh, Pratap; Shrivastava, Purushottam
2011-01-01
RRCAT is developing a Vertical Test Stand (VTS) to test and qualify 1.3 GHz/650 MHz, SCRF Cavities in collaboration with Fermi National Accelerator Laboratory (FNAL) under Indian Institutions' Fermilab Collaboration. The technical details for VTS is being provided by FNAL, USA. The RF System of VTS needs to provide stable RF power to SCRF cavity with control of amplitude, relative phase and frequency. The incident, reflected, transmitted power and field decay time constant of the cavity are measured to evaluate cavity performance parameters (E, Qo). RF Power is supplied via 500 W Solid State amplifier, 1270-1310 MHz being developed by PHPMS, RRCAT. VTS system is controlled by PXI Platform and National Instruments LabVIEW software. Low Level RF (LLRF) system is used to track the cavity frequency using Phase Locked Loop (PLL). The system is comprised of several integrated functional modules which would be assembled, optimized, and tested separately. Required components and instruments have been identified and procurement for the same is underway. Inhouse development for the Solid State RF amplifier and instrument interfacing is in progress. This paper describes the progress on the development of the RF system for VTS. (author)
A study of polaritonic transparency in couplers made from excitonic materials
Energy Technology Data Exchange (ETDEWEB)
Singh, Mahi R.; Racknor, Chris [Department of Physics and Astronomy, Western University, London, Ontario N6A 3K7 (Canada)
2015-03-14
We have studied light matter interaction in quantum dot and exciton-polaritonic coupler hybrid systems. The coupler is made by embedding two slabs of an excitonic material (CdS) into a host excitonic material (ZnO). An ensemble of non-interacting quantum dots is doped in the coupler. The bound exciton polariton states are calculated in the coupler using the transfer matrix method in the presence of the coupling between the external light (photons) and excitons. These bound exciton-polaritons interact with the excitons present in the quantum dots and the coupler is acting as a reservoir. The Schrödinger equation method has been used to calculate the absorption coefficient in quantum dots. It is found that when the distance between two slabs (CdS) is greater than decay length of evanescent waves the absorption spectrum has two peaks and one minimum. The minimum corresponds to a transparent state in the system. However, when the distance between the slabs is smaller than the decay length of evanescent waves, the absorption spectra has three peaks and two transparent states. In other words, one transparent state can be switched to two transparent states when the distance between the two layers is modified. This could be achieved by applying stress and strain fields. It is also found that transparent states can be switched on and off by applying an external control laser field.
Benedikovic, Daniel; Alonso-Ramos, Carlos; Pérez-Galacho, Diego; Guerber, Sylvain; Vakarin, Vladyslav; Marcaud, Guillaume; Le Roux, Xavier; Cassan, Eric; Marris-Morini, Delphine; Cheben, Pavel; Boeuf, Frédéric; Baudot, Charles; Vivien, Laurent
2017-09-01
Grating couplers enable position-friendly interfacing of silicon chips by optical fibers. The conventional coupler designs call upon comparatively complex architectures to afford efficient light coupling to sub-micron silicon-on-insulator (SOI) waveguides. Conversely, the blazing effect in double-etched gratings provides high coupling efficiency with reduced fabrication intricacy. In this Letter, we demonstrate for the first time, to the best of our knowledge, the realization of an ultra-directional L-shaped grating coupler, seamlessly fabricated by using 193 nm deep-ultraviolet (deep-UV) lithography. We also include a subwavelength index engineered waveguide-to-grating transition that provides an eight-fold reduction of the grating reflectivity, down to 1% (-20 dB). A measured coupling efficiency of -2.7 dB (54%) is achieved, with a bandwidth of 62 nm. These results open promising prospects for the implementation of efficient, robust, and cost-effective coupling interfaces for sub-micrometric SOI waveguides, as desired for large-volume applications in silicon photonics.
Zhang, Fan; Yun, Han; Wang, Yun; Lu, Zeqin; Chrostowski, Lukas; Jaeger, Nicolas A F
2017-01-15
We design and demonstrate a compact broadband polarization beam splitter (PBS) using a symmetric directional coupler with sinusoidal bends on a silicon-on-insulator platform. The sinusoidal bends in our PBS suppress the power exchange between two parallel symmetric strip waveguides for the transverse-electric (TE) mode, while allowing for the maximum power transfer to the adjacent waveguide for the transverse-magnetic (TM) mode. Our PBS has a nominal coupler length of 8.55 μm, and it has an average extinction ratio (ER) of 12.0 dB for the TE mode, an average ER of 20.1 dB for the TM mode, an average polarization isolation (PI) of 20.6 dB for the through port, and an average PI of 11.5 dB for the cross port, all over a bandwidth of 100 nm.
Tailoring design and fabrication of capacitive RF MEMS switches for K-band applications
Quaranta, Fabio; Persano, Anna; Capoccia, Giovanni; Taurino, Antonietta; Cola, Adriano; Siciliano, Pietro; Lucibello, Andrea; Marcelli, Romolo; Proietti, Emanuela; Bagolini, Alvise; Margesin, Benno; Bellutti, Pierluigi; Iannacci, Jacopo
2015-05-01
Shunt capacitive radio-frequency microelectromechanical (RF MEMS) switches were modelled, fabricated and characterized in the K-band domain. Design allowed to predict the RF behaviour of the switches as a function of the bridge geometric parameters. The modelled switches were fabricated on silicon substrate, using a surface micromachining approach. In addition to the geometric parameters, the material structure in the bridge-actuator area was modified for switches fabricated on the same wafer, thanks to the removal/addition of two technological steps of crucial importance for RF MEMS switches performance, which are the use of the sacrificial layer and the deposition of a floating metal layer on the actuator. Surface profilometry analysis was used to check the material layer structure in the different regions of the bridge area as well as to investigate the mechanical behaviour of the moveable bridge under the application of a loaded force. The RF behaviour of all the fabricated switches was measured, observing the impact on the isolation of the manipulation of the bridge size and of the variations in the fabrication process.
Wang, Jing; Qi, Minghao; Xuan, Yi; Huang, Haiyang; Li, You; Li, Ming; Chen, Xin; Jia, Qi; Sheng, Zhen; Wu, Aimin; Li, Wei; Wang, Xi; Zou, Shichang; Gan, Fuwan
2014-11-17
A novel silicon-on-insulator (SOI) polarization splitter-rotator (PSR) with a large fabrication tolerance is proposed based on cascaded multimode interference (MMI) couplers and an assisted mode-evolution taper. The tapers are designed to adiabatically convert the input TM(0) mode into the TE(1) mode, which will output as the TE(0) mode after processed by the subsequent MMI mode converter, 90-degree phase shifter (PS) and MMI 3 dB coupler. The numerical simulation results show that the proposed device has a silicon photonics technology.
Low power RF measurements of travelling wave type linear accelerator
International Nuclear Information System (INIS)
Reddy, Sivananda; Wanmode, Yashwant; Bhisikar, A.; Shrivastava, Purushottam
2015-01-01
RRCAT is engaged in the development of travelling wave (TW) type linear accelerator for irradiation of industrial and agricultural products. TW accelerator designed for 2π/3 mode to operate at frequency of 2856 MHz. It consists of input coupler, buncher cells, regular cells and output coupler. Low power measurement of this structure includes measurement of resonant frequency of the cells for different resonant modes and quality factor, tuning of input-output coupler and measurement of phase advance per cell and electric field in the structure. Steele's non-resonant perturbation technique has been used for measurement of phase advance per cell and electric field in the structure. Kyhl's method has been used for the tuning of input-output coupler. Computer based automated bead pull set-up has been developed for measurement of phase advance per cell and electric field profile in the structure. All the codes are written in Python for interfacing of Vector Network Analyzer (VNA) , stepper motor with computer. These codes also automate the measurement process. This paper describes the test set- up for measurement and results of measurement of travelling wave type linear accelerating structure. (author)
Energy Technology Data Exchange (ETDEWEB)
Johnston, A.; Rax, B.G. [California Institute of Technology, Jet Propulsion Laboratory, Pasadena (United States)
1999-07-01
This paper discusses proton degradation of linear and digital opto-couplers. One obvious way to harden opto-coupler technologies is to select LEDs (light emitting diodes) that are more resistant to displacement damage. A direct comparison is made of degradation of a commercial linear opto-coupler from one manufactured with a modified version of the same device with a different LED technology. Other factors, including degradation of optical photoresponse and transistor gain are also discussed, along with basic comparisons of digital and analog opto-couplers. The experimental work has been made with 50 MeV protons. 3 underlying factors contribute to opto-coupler degradation. The most important factor is LED degradation, it is possible to select opto-coupler with double-heterojunction LEDs that are inherently more resistant to displacement damage. The second factor is gain degradation that is particularly important for opto-couplers with sensitive LEDs because the light output decreases so much at low radiation levels. The third factor, optical photoresponse is the largest contribution to CTR (current transfer ratio) degradation for opto-couplers with improved LED hardness. Photoresponse degradation depends on wavelength because the absorption coefficient is wavelength dependent. (A.C.)
Suspended mid-infrared fiber-to-chip grating couplers for SiGe waveguides
Favreau, Julien; Durantin, Cédric; Fédéli, Jean-Marc; Boutami, Salim; Duan, Guang-Hua
2016-03-01
Silicon photonics has taken great importance owing to the applications in optical communications, ranging from short reach to long haul. Originally dedicated to telecom wavelengths, silicon photonics is heading toward circuits handling with a broader spectrum, especially in the short and mid-infrared (MIR) range. This trend is due to potential applications in chemical sensing, spectroscopy and defense in the 2-10 μm range. We previously reported the development of a MIR photonic platform based on buried SiGe/Si waveguide with propagation losses between 1 and 2 dB/cm. However the low index contrast of the platform makes the design of efficient grating couplers very challenging. In order to achieve a high fiber-to-chip efficiency, we propose a novel grating coupler structure, in which the grating is locally suspended in air. The grating has been designed with a FDTD software. To achieve high efficiency, suspended structure thicknesses have been jointly optimized with the grating parameters, namely the fill factor, the period and the grating etch depth. Using the Efficient Global Optimization (EGO) method we obtained a configuration where the fiber-to-waveguide efficiency is above 57 %. Moreover the optical transition between the suspended and the buried SiGe waveguide has been carefully designed by using an Eigenmode Expansion software. Transition efficiency as high as 86 % is achieved.
Design study of an S-band RF cavity of a dual-energy electron LINAC for the CIS
Lee, Byeong-No; Park, Hyungdal; Song, Ki-baek; Li, Yonggui; Lee, Byung Cheol; Cha, Sung-su; Lee, Jong-Chul; Shin, Seung-Wook; Chai, Jong-seo
2014-01-01
The design of a resonance frequency (RF) cavity for the dual-energy S-band electron linear accelerator (LINAC) has been carried out for the cargo inspection system (CIS). This Standing-wave-type RF cavity is operated at a frequency under the 2856-MHz resonance frequency and generates electron beams of 9 MeV (high mode) and 6 MeV (low mode). The electrons are accelerated from the initial energy of the electron gun to the target energy (9 or 6 MeV) inside the RF cavity by using the RF power transmitted from a 5.5-MW-class klystron. Then, electron beams with a 1-kW average power (both high mode and low mode) bombard an X-ray target a 2-mm spot size. The proposed accelerating gradient was 13 MV/m, and the designed Q value was about 7100. On going research on 15-MeV non-destructive inspections for military or other applications is presented.
Shang, Kuanping; Pathak, Shibnath; Liu, Guangyao; Feng, Shaoqi; Li, Siwei; Lai, Weicheng; Yoo, S J B
2017-05-01
We designed and demonstrated a tri-layer Si3N4/SiO2 photonic integrated circuit capable of vertical interlayer coupling with arbitrary splitting ratios. Based on this multilayer photonic integrated circuit platform with each layer thicknesses of 150 nm, 50 nm, and 150 nm, we designed and simulated the vertical Y-junctions and 3D couplers with arbitrary power splitting ratios between 1:10 and 10:1 and with negligible(< -50 dB) reflection. Based on the design, we fabricated and demonstrated tri-layer vertical Y-junctions with the splitting ratios of 1:1 and 3:2 with excess optical losses of 0.230 dB. Further, we fabricated and demonstrated the 1 × 3 3D couplers with the splitting ratio of 1:1:4 for symmetric structures and variable splitting ratio for asymmetric structures.
Nerguizian, Vahe; Rafaf, Mustapha
2004-08-01
This article describes and provides valuable information for companies and universities with strategies to start fabricating MEMS for RF/Microwave and millimeter wave applications. The present work shows the infrastructure developed for RF/Microwave and millimeter wave MEMS platforms, which helps the identification, evaluation and selection of design tools and fabrication foundries taking into account packaging and testing. The selected and implemented simple infrastructure models, based on surface and bulk micromachining, yield inexpensive and innovative approaches for distributed choices of MEMS operating tools. With different educational or industrial institution needs, these models may be modified for specific resource changes using a careful analyzed iteration process. The inputs of the project are evaluation selection criteria and information sources such as financial, technical, availability, accessibility, simplicity, versatility and practical considerations. The outputs of the project are the selection of different MEMS design tools or software (solid modeling, electrostatic/electromagnetic and others, compatible with existing standard RF/Microwave design tools) and different MEMS manufacturing foundries. Typical RF/Microwave and millimeter wave MEMS solutions are introduced on the platform during the evaluation and development phases of the project for the validation of realistic results and operational decision making choices. The encountered challenges during the investigation and the development steps are identified and the dynamic behavior of the infrastructure is emphasized. The inputs (resources) and the outputs (demonstrated solutions) are presented in tables and flow chart mode diagrams.
International Nuclear Information System (INIS)
Kitchen, Ronald.
1993-01-01
Radio frequency radiation can be dangerous in a number of ways. Hazards include electromagnetic compatibility and interference, electro-explosive vapours and devices, and direct effects on the human body. This book is a general introduction to the sources and nature of RF radiation. It describes the ways in which our current knowledge, based on relevant safety standards, can be used to safeguard people from any harmful effects of RF radiation. The book is designed for people responsible for, or concerned with, safety. This target audience will primarily be radio engineers, but includes those skilled in other disciplines including medicine, chemistry or mechanical engineering. The book covers the problems of RF safety management, including the use of measuring instruments and methods, and a review of current safety standards. The implications for RF design engineers are also examined. (Author)
Preventing distortion of quick couplers of hoses of central pipe lines--a cheap and simple method.
Directory of Open Access Journals (Sweden)
Kamath S
1995-01-01
Full Text Available A cheap and practical approach of steel chains attached to the station outlet quick couplers helps in maintaining the shape of the quick couplers and ensures their effective functioning over a long period of time and avoids mishap of connection due to damage of these couplers.
International Nuclear Information System (INIS)
Alesini, D.; Bellaveglia, M.; Biagini, M.E.; Boni, R.; Brönnimann, M.; Cardelli, F.; Chimenti, P.; Clementi, R.; Di Pirro, G.; Di Raddo, R.; Ferrario, M.; Ficcadenti, L.; Gallo, A.; Kalt, R.; Lollo, V.; Palumbo, L.; Piersanti, L.; Schilcher, T.
2016-01-01
The energy upgrade of the SPARC-LAB photo-injector at LNF-INFN (Frascati, Italy) has been originally conceived replacing one low gradient (13 MV/m) 3 m long SLAC type S-band traveling wave (TW) section with two 1.4 m long C-band accelerating sections. Due to the higher gradients reached by such structures, a higher energy beam can be obtained within the same accelerator footprint length. The use of C-band structures for electron acceleration has been adopted in a few FEL linacs in the world, among others, the Japanese Free Electron Laser at SPring-8 and the SwissFEL at Paul Scherrer Institute (PSI). The C-band sections are traveling wave, constant impedance structures with symmetric input and output axial couplers. Their design has been optimized for the operation with a SLED RF pulse compressor. In this paper we briefly review their design criteria and we focus on the construction, tuning, low and high-power RF tests. We also illustrate the design and realization of the dedicated low level RF system that has been done in collaboration with PSI in the framework of the EU TIARA project. Preliminary experimental results appear to confirm the operation of such structures with accelerating gradients larger than 35 MV/m.
Energy Technology Data Exchange (ETDEWEB)
Alesini, D.; Bellaveglia, M.; Biagini, M.E.; Boni, R. [INFN Laboratori Nazionali di Frascati, Via Enrico Fermi 40, 00044, Frascati (Italy); Brönnimann, M. [Paul Scherrer Institut, 5232 Villigen (Switzerland); Cardelli, F. [INFN Sezione di Roma, P.le Aldo Moro 2, 00185, Roma (Italy); Università di Roma “La Sapienza”, P.le Aldo Moro 2, 00185, Roma (Italy); Chimenti, P.; Clementi, R.; Di Pirro, G.; Di Raddo, R.; Ferrario, M. [INFN Laboratori Nazionali di Frascati, Via Enrico Fermi 40, 00044, Frascati (Italy); Ficcadenti, L. [INFN Sezione di Roma, P.le Aldo Moro 2, 00185, Roma (Italy); Università di Roma “La Sapienza”, P.le Aldo Moro 2, 00185, Roma (Italy); Gallo, A. [INFN Laboratori Nazionali di Frascati, Via Enrico Fermi 40, 00044, Frascati (Italy); Kalt, R. [Paul Scherrer Institut, 5232 Villigen (Switzerland); Lollo, V. [INFN Laboratori Nazionali di Frascati, Via Enrico Fermi 40, 00044, Frascati (Italy); Palumbo, L. [INFN Sezione di Roma, P.le Aldo Moro 2, 00185, Roma (Italy); Università di Roma “La Sapienza”, P.le Aldo Moro 2, 00185, Roma (Italy); Piersanti, L., E-mail: luca.piersanti@lnf.infn.it [INFN Sezione di Roma, P.le Aldo Moro 2, 00185, Roma (Italy); Università di Roma “La Sapienza”, P.le Aldo Moro 2, 00185, Roma (Italy); Schilcher, T. [Paul Scherrer Institut, 5232 Villigen (Switzerland)
2016-11-21
The energy upgrade of the SPARC-LAB photo-injector at LNF-INFN (Frascati, Italy) has been originally conceived replacing one low gradient (13 MV/m) 3 m long SLAC type S-band traveling wave (TW) section with two 1.4 m long C-band accelerating sections. Due to the higher gradients reached by such structures, a higher energy beam can be obtained within the same accelerator footprint length. The use of C-band structures for electron acceleration has been adopted in a few FEL linacs in the world, among others, the Japanese Free Electron Laser at SPring-8 and the SwissFEL at Paul Scherrer Institute (PSI). The C-band sections are traveling wave, constant impedance structures with symmetric input and output axial couplers. Their design has been optimized for the operation with a SLED RF pulse compressor. In this paper we briefly review their design criteria and we focus on the construction, tuning, low and high-power RF tests. We also illustrate the design and realization of the dedicated low level RF system that has been done in collaboration with PSI in the framework of the EU TIARA project. Preliminary experimental results appear to confirm the operation of such structures with accelerating gradients larger than 35 MV/m.
A 201 MHz RF cavity design with non-stressed pre-curved Be windows for muon cooling channels
International Nuclear Information System (INIS)
Li, Derun; Ladran, A.; Staples, J.; Virostek, S.; Zisman, M.; Lau, W.; Yang, S.; Rimmer, R.A.
2003-01-01
We present a 201-MHz RF cavity design for muon cooling channels with non-stressed and pre-curved Be foils to terminate the beam apertures. The Be foils are necessary to improve the cavity shunt impedance with large beam apertures needed for accommodating large transverse size muon beams. Be is a low-Z material with good electrical and thermal properties. It presents an almost transparent window to muon beams, but terminates the RF cavity electro-magnetically. Previous designs use pre-stressed flat Be foils in order to keep cavity from detuning resulted from RF heating on the window surface. Be foils are expensive, and it is difficult to make them under desired tension. An alternative design is to use pre-curved and non-stressed Be foils where the buckling direction is known, and frequency shifts can be properly predicted. We will present mechanical simulations on the Be foils in this paper
Enhancement of entanglement in the nonlinear optical coupler by homodyne-mediated feedback
Energy Technology Data Exchange (ETDEWEB)
Ke Shasha [Department of Physics, Huazhong Normal University, Wuhan 430079 (China); Cheng Guiping [Department of Physics, Huazhong Normal University, Wuhan 430079 (China); Zhang Lihui [Department of Physics, Jianghan University, Wuhan 430056 (China); Li, Gao-xiang [Department of Physics, Huazhong Normal University, Wuhan 430079 (China)
2007-07-28
The enhancement of the intracavity entanglement of a nonlinear coupler via homodyne-mediated quantum feedback is investigated. It is found that the feedback can effectively enhance the squeezing, entanglement and purity of a two-mode field in the nonlinear coupler by appropriately choosing the quadrature angle at which the quantum feedback is introduced.
Design of RF structures for a superconducting proton linac
International Nuclear Information System (INIS)
Pande, Rajni; Roy, Shweta; Rao, S.V.L.S.; Krishnagopal, S.; Singh, P.
2013-01-01
One of the main components of the Accelerator Driven System (ADS) programme in India is a 1 GeV, high intensity CW proton accelerator that will be superconducting after the radio-frequency quadrupole (RFQ), i.e. after 3 MeV. The superconducting linac will consist of various superconducting structures like Half Wave Resonators, Spoke Resonators and elliptical cavities, operating at RF frequencies of 162.5 MHz, 325 MHz and 650 MHz. The paper will discuss the optimization of the electromagnetic design of the various superconducting structures. (author)
2×2 polymeric electro-optic MZI switch using multimode interference couplers
Li, H. P.; Liao, J. K.; Tang, X. G.; Lu, R. G.; Liu, Y. Z.
2009-11-01
We present the design of a 2×2 photonic switch operating at 1.55-μm wavelength using electro-optic (EO) polymer waveguides. A Mach-Zehnder interferometer (MZI) is used to implement the proposed switch in which two identical 2×2 multimode interference (MMI) couplers are connected by two identical parallel single mode waveguides (two MZI arms). These two single-mode waveguides with electrodes allow modulating the phase difference between the two MZI arms based on the EO effect. In the proposed switch, the EO polymer, IPC-E/polysulfone, is used for the core layer of optical waveguides. UV15 and NOA61 are employed for the lower and upper cladding layers, respectively. The singlemode waveguide structure and 2×2 MMI coupler have been designed and analyzed for the EO switch. Device performance has been simulated using the beam propagation method. It is found that the switch performance is most sensitive to the MMI width and less sensitive to the MMI length. Optimized structure has been obtained for the 2×2 polymeric EO switch, which has a crosstalk level better than -25 dB and insertion loss lower than -1.8 dB. This performance makes the switch a potential candidate for practical use in photonic systems.
RF linac designs with beams in thermal equilibrium
International Nuclear Information System (INIS)
Reiser, M.; Brown, N.
1996-01-01
Beams in conventional radio-frequency linear accelerators (rf linacs) usually have a transverse temperature which is much larger than the longitudinal temperature. With high currents, space charge forces couple the transverse and longitudinal particle motions, driving the beam toward thermal equilibrium, which leads to emittance growth and halo formation. A design strategy is proposed in which the beam has equal transverse and longitudinal temperatures through the entire linac, avoiding these undesirable effects. For such equipartitioned linac beams, simple analytical relationships can be derived for the bunch size, tune depression, and other parameters as a function of beam intensity, emittance, and external focusing. These relations were used to develop three conceptual designs for a 938 MeV, 100 mA proton linac with different tune depressions, which are presented in this paper. copyright 1996 American Institute of Physics
Multiplexing of adjacent vortex modes with the forked grating coupler
Nadovich, Christopher T.; Kosciolek, Derek J.; Crouse, David T.; Jemison, William D.
2017-08-01
For vortex fiber multiplexing to reach practical commercial viability, simple silicon photonic interfaces with vortex fiber will be required. These interfaces must support multiplexing. Toward this goal, an efficient singlefed multimode Forked Grating Coupler (FGC) for coupling two different optical vortex OAM charges to or from the TE0 and TE1 rectangular waveguide modes has been developed. A simple, apodized device implemented with e-beam lithography and a conventional dual-etch processing on SOI wafer exhibits low crosstalk and reasonable mode match. Advanced designs using this concept are expected to further improve performance.
Directory of Open Access Journals (Sweden)
S. Maktoobi
2014-10-01
Full Text Available Switching is a principle process in digital computers and signal processing systems. The growth of optical signal processing systems, draws particular attention to design of ultra-fast optical switches. In this paper, All Optical Switches in linear state Based On photonic crystal Directional coupler is analyzed and simulated. Among different methods, the finite difference time domain method (FDTD is a preferable method and is used. We have studied the application of photonic crystal lattices, the physics of optical switching and photonic crystal Directional coupler. In this paper, Electric field intensity and the power output that are two factors to improve the switching performance and the device efficiency are investigated and simulated. All simulations are performed by COMSOL software.
Study and development of an input coupler for the future TESLA collider
International Nuclear Information System (INIS)
Dupery, C.
1996-01-01
The TESLA (TeV Superconducting Linear Accelerator) is operating with a high frequency cavity resonator input coupler. Some technical restraints (such as thermal, mechanical, electrical, vacuum, multipactor discharge phenomena) constrain the development of this coupler. In order to solve these problems, studies have been performed at the French Atomic Energy Commission (CEA) and are presented in this paper
Design and development of R.F. LINAC accelerator components
International Nuclear Information System (INIS)
Abhay Kumar; Guha, S.; Balasubramaniam, R.; Jawale, S.B.
2003-01-01
Full text: Radio frequency linear accelerator, a high power electron LINAC technology, is being developed at BARC. These accelerators are considered to be the most compact and effective for a given power capacity. Important application areas of this LINAC include medical sterilization, food preservation, pollution control, semiconductor industries, radiation therapy and material science. Center for Design and Manufacture (CDM), BARC has been entrusted with the design, development and manufacturing of various mechanical components of the accelerator. Most critical and precision components out of them are Diagnostic chamber, Faraday cup, Drift tube and R.F. cavities. This paper deals with the design aspects in respect of Ultra high vacuum compatibility and the mechanism of operation. Also this paper discusses the state-of-art technology for machining of intricate contour using specially designed poly crystalline diamond tool and the inspection methodology developed to minimize the measurement errors on the machined contour. Silver brazing technique employed to join the LINAC cavities is also described in detail
International Nuclear Information System (INIS)
Mark S. Champion et al.
2001-01-01
A research and development program is underway to construct superconducting cavities to be used for radiofrequency separation of a Kaon beam at Fermilab. The design calls for installation of twelve 13-cell cavities operating in the 3.9 GHz transverse mode with a deflection gradient of 5 MV/m. They present the mechanical, cryogenic and vacuum design of the cavity, cryomodule, rf power coupler, cold tuner and supporting hardware. The electromagnetic design of the cavity is presented in a companion paper by Wanzenberg and McAshan. The warm tuning system (for field flatness) and the vertical test system is presented along with test results of bench measurements and cold tests on single-cell and five-cell prototypes
RF phase distribution systems at the SLC
International Nuclear Information System (INIS)
Jobe, R.K.; Schwarz, H.D.
1989-04-01
Modern large linear accelerators require RF distribution systems with minimal phase drifts and errors. Through the use of existing RF coaxial waveguides, and additional installation of phase reference cables and monitoring equipment, stable RF distribution for the SLC has been achieved. This paper discusses the design and performance of SLAC systems, and some design considerations for future colliders. 6 refs., 4 figs
DEFF Research Database (Denmark)
Ding, Yunhong; Ye, Feihong; Peucheret, Christophe
2014-01-01
We design and fabricate a compact multi-core fiber fan-in/fan-out using a fully-etched grating coupler array on the SOI platform. Lowest coupling loss of 6.8 dB with 3 dB bandwidth of 48 nm and crosstalk lower than ×32 dB are demonstrated.......We design and fabricate a compact multi-core fiber fan-in/fan-out using a fully-etched grating coupler array on the SOI platform. Lowest coupling loss of 6.8 dB with 3 dB bandwidth of 48 nm and crosstalk lower than ×32 dB are demonstrated....
Technology development of solid state rf systems at 350 MHz and 325 MHz for RF accelerator
International Nuclear Information System (INIS)
Rama Rao, B.V.; Mishra, J.K.; Pande, Manjiri; Gupta, S.K.
2011-01-01
For decades vacuum tubes and klystrons have been used in high power application such as RF accelerators and broadcast transmitters. However, now, the solid-state technology can give power output in kilowatt regime. Higher RF power output can be achieved by combining several solid-state power amplifier modules using power combiners. This technology presents several advantages over traditional RF amplifiers, such as simpler start-up procedure, high modularity, high redundancy and flexibility, elimination of high voltage supplies and high power circulators, low operational cost, online maintenance without shut down of RF power station and no warm up time. In BARC, solid state amplifier technology development is being done both at 350 MHz and 325 MHz using RF transistors such as 1 kW LDMOS and 350 Watt VDMOS. Topology of input and output matching network in RF modules developed, consist of two L type matching sections with each section having a combination of series micro-strip line and parallel capacitor. The design is of equal Q for both the sections and of 25 ohm characteristics impedance of micro strip lines. Based on this, lengths of micro strips lines and values of shunt capacitors have been calculated. The calculated and simulated values of network elements have been compared. Similarly power combiners have been designed and developed based on Wilkinson techniques without internal resistors and using coaxial technology. This paper presents design and development of RF power amplifier modules, associated power combiner technologies and then integrated RF power amplifier. (author)
Design, construction and test of RF solid state power amplifier for IRANCYC-10
Azizi, H.; Dehghan, M.; Abbasi Davani, F.; Ghasemi, F.
2018-03-01
In this paper, design, simulation and construction of a high power amplifier to provide the required power of a cyclotron accelerator (IRANCYC-10) is presented step-by-step. The Push-Pull designed amplifier can generate 750 W at the operating frequency of 71 MHz continous wave (CW). In this study, achieving the best efficiency of the amplifier, as well as reducing overall volume using baluns, were two important goals. The new offered water-cooled heat sink was used for cooling the amplifier which increases the operating life of the transistor. The gain and PAE of the SSPA were obtained 20 dB and 77.7%, respectively. The simulated and measured RF results are in good agreement with each other. The results show that, using an RF transformer in matching impedance of matching networks, it causes a smaller size and also a better amplifier performance.
Conceptual design of a bright electron injector based on a laser-driven photocathode rf electron gun
International Nuclear Information System (INIS)
Chattopadhyay, S.; Chen, Y.J.; Hopkins, D.; Kim, K.J.; Kung, A.; Miller, R.; Sessler, A.; Young, T.
1988-09-01
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 picosecond laser system and magnetic bunching section. 4 refs., 5 figs., 2 tabs
Thakur, S. K.; Kumar, Y.
2018-05-01
This paper described the detailed design, development and testing of high voltage power supply (‑30 kV, 3.2 A) and different power supplies for biasing electrodes of Inductive Output Tube (IOT) based high power Radio Frequency (RF) amplifier. This IOT based RF amplifier is further used for pursuing research and development activity in superconducting RF cavity project at Variable Energy Cyclotron Centre (VECC) Kolkata. The state-of-the-art technology of IOT-based high power RF amplifier is designed, developed, and tested at VECC which is the first of its kind in India. A high voltage power supply rated at negative polarity of 30 kV dc/3.2 A is required for biasing cathode of IOT with crowbar protection circuit. This power supply along with crowbar protection system is designed, developed and tested at VECC for testing the complete setup. The technical difficulties and challenges occured during the design of cathode power supply, its crowbar protection techniques along with other supported power supplies i.e. grid and ion pump power supplies are discussed in this paper.
International Nuclear Information System (INIS)
2002-01-01
The design and performance of higher order mode (HOM) dampers for the SPEAR 2 RF system is presented. The SPEAR beam had experienced occasional periods of instability due to transverse oscillations which were driven by HOMs in the RF cavities. A substantial fraction of this RF energy was coupled out of the cavity into the waveguide connecting the cavity to the klystron. This waveguide was modified by adding a stub of smaller cross section, terminated by a ferrite tile load, to the system. Design considerations of the load, and its effect on HOMs and beam stability will be discussed
Very short intracavity directional coupler for high-speed communication
Griffel, Giora
1993-07-01
We propose a novel intracavity modulator/switch that consists of a directional-coupler located inside a Fabry-Perot cavity. The back mirror of the cavity has a unit reflectivity so that both input and output signals are at the same side. In this way we obtain a two-port, single side element, with coupling length of 83.5 μm, which is the shortest modulation coupler proposed so far. The upper frequency limit due to photon lifetime is 275 GHz, which is well over the bandwidth constraints of microwave lumped structures. A unified approach for the analysis of this device and other similar structures is presented and discussed.
DEFF Research Database (Denmark)
Ding, Yunhong; Ou, Haiyan; Peucheret, Christophe
2014-01-01
We design and fabricate an ultra-high coupling efficiency fully-etched apodized grating coupler on the SOI platform using photonic crystals and bonded aluminum mirror. Ultra-high coupling efficiency of -0.78 dB with a 3 dB bandwidth of 74 nm are demonstrated.......We design and fabricate an ultra-high coupling efficiency fully-etched apodized grating coupler on the SOI platform using photonic crystals and bonded aluminum mirror. Ultra-high coupling efficiency of -0.78 dB with a 3 dB bandwidth of 74 nm are demonstrated....
Demonstration of a High-Order Mode Input Coupler for a 220-GHz Confocal Gyrotron Traveling Wave Tube
Guan, Xiaotong; Fu, Wenjie; Yan, Yang
2018-02-01
A design of high-order mode input coupler for 220-GHz confocal gyrotron travelling wave tube is proposed, simulated, and demonstrated by experimental tests. This input coupler is designed to excite confocal TE 06 mode from rectangle waveguide TE 10 mode over a broadband frequency range. Simulation results predict that the optimized conversion loss is about 2.72 dB with a mode purity excess of 99%. Considering of the gyrotron interaction theory, an effective bandwidth of 5 GHz is obtained, in which the beam-wave coupling efficiency is higher than half of maximum. The field pattern under low power demonstrates that TE 06 mode is successfully excited in confocal waveguide at 220 GHz. Cold test results from the vector network analyzer perform good agreements with simulation results. Both simulation and experimental results illustrate that the reflection at input port S11 is sensitive to the perpendicular separation of two mirrors. It provides an engineering possibility for estimating the assembly precision.
Ka-Band Rf Transmission Line Components for a High-Gradient Linear Accelerator. Final report
International Nuclear Information System (INIS)
Hirshfield, Jay L.
2005-01-01
High-power, high-vacuum prototypes of a variety of components for use at 34 GHz were developed. These include waveguide tapers, right-angle miter bends, windows, mode converters, power combiners, mode launchers, phase shifters, dual directional couplers, and loads. High-power, high-vacuum prototypes of all the components were built and tested up to 45 MW, using the Omega-P 34-GHz magnicon. Peak power limits for the components were determined using a quasi-optical rf pulse compressor, developed under a companion project. The components and the magnicon were configured into a user's facility for research and development by others on high-gradient accelerator structures for a future high-energy electron-positron collider.
SNS Low-Level RF Control System Design and Performance
Ma, Hengjie; Crofford, Mark; Doolittle, Lawrence; Kasemir, Kay-Uwe; Piller, Maurice; Ratti, Alessandro
2005-01-01
A full digital Low-Level RF controller has been developed for SNS LINAC. Its design is a good example of a modern digital implementation of the classic control theory. The digital hardware for all the control and DSP functionalities, including the final vector modulation, is implemented on a single high-density FPGA. Two models for the digital hardware have been written in VHDL and Verilog respectively, based on a very low latency control algorithm, and both have been being used for supporting the testing and commissioning the LINAC to the date. During the commissioning, the flexibility and ability for precise controls that only digital design on a larger FPGA can offer has proved to be a necessity for meeting the great challenge of a high-power pulsed SCL.
Al-Eryani, Yasser F.
2018-03-07
In this paper, a multiuser mixed radio frequency (RF) and hybrid free-space optical (FSO)/RF system is considered, where multiple mobile users transmit their data to an intermediate decode-and-forward relay node through RF links using a virtual multiple-input multipleoutput (MIMO) system, and the relay node forwards the multiplexed data of all users through a FSO link that is supported by a RF MIMO backup system to the destination. The relay node is equipped with a buffer in the physical layer for temporal storage of the users\\' data until the best channel conditions at the relay-destination link aremet. For this communication setup, we first propose a transmission protocol that achieves a multiplexing gain through a virtual MIMO system. After that, we derive closed-form expressions for the end-to-end outage probability, asymptotic outage probability, average symbol error rate, and the ergodic capacity when considering the delay-tolerant (finite buffer size) scenario. The results show that buffering in the physical layer provides a significant enhancement to the system performance (outage, error rate, and ergodic capacity). It is also found that pointing error and severe weather turbulence conditions become more tolerable with the existence of the relay\\'s buffer and RF backup link (in the second hop). In addition, the proposed virtual MIMO scheme shows a significant performance enhancement at a high number of receiving antennas, which introduces potential lowcomplexity diversity gain-based massive MIMO schemes.
Al-Eryani, Yasser F.; Salhab, Anas; Zummo, Salam A.; Alouini, Mohamed-Slim
2018-01-01
In this paper, a multiuser mixed radio frequency (RF) and hybrid free-space optical (FSO)/RF system is considered, where multiple mobile users transmit their data to an intermediate decode-and-forward relay node through RF links using a virtual multiple-input multipleoutput (MIMO) system, and the relay node forwards the multiplexed data of all users through a FSO link that is supported by a RF MIMO backup system to the destination. The relay node is equipped with a buffer in the physical layer for temporal storage of the users' data until the best channel conditions at the relay-destination link aremet. For this communication setup, we first propose a transmission protocol that achieves a multiplexing gain through a virtual MIMO system. After that, we derive closed-form expressions for the end-to-end outage probability, asymptotic outage probability, average symbol error rate, and the ergodic capacity when considering the delay-tolerant (finite buffer size) scenario. The results show that buffering in the physical layer provides a significant enhancement to the system performance (outage, error rate, and ergodic capacity). It is also found that pointing error and severe weather turbulence conditions become more tolerable with the existence of the relay's buffer and RF backup link (in the second hop). In addition, the proposed virtual MIMO scheme shows a significant performance enhancement at a high number of receiving antennas, which introduces potential lowcomplexity diversity gain-based massive MIMO schemes.
Advanced Output Coupling for High Power Gyrotrons
Energy Technology Data Exchange (ETDEWEB)
Read, Michael [Calabazas Creek Research, Inc., San Mateo, CA (United States); Ives, Robert Lawrence [Calabazas Creek Research, Inc., San Mateo, CA (United States); Marsden, David [Calabazas Creek Research, Inc., San Mateo, CA (United States); Collins, George [Calabazas Creek Research, Inc., San Mateo, CA (United States); Temkin, Richard [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Guss, William [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Lohr, John [General Atomics, La Jolla, CA (United States); Neilson, Jeffrey [Lexam Research, Redwood City, CA (United States); Bui, Thuc [Calabazas Creek Research, Inc., San Mateo, CA (United States)
2016-11-28
The Phase II program developed an internal RF coupler that transforms the whispering gallery RF mode produced in gyrotron cavities to an HE11 waveguide mode propagating in corrugated waveguide. This power is extracted from the vacuum using a broadband, chemical vapor deposited (CVD) diamond, Brewster angle window capable of transmitting more than 1.5 MW CW of RF power over a broad range of frequencies. This coupling system eliminates the Mirror Optical Units now required to externally couple Gaussian output power into corrugated waveguide, significantly reducing system cost and increasing efficiency. The program simulated the performance using a broad range of advanced computer codes to optimize the design. Both a direct coupler and Brewster angle window were built and tested at low and high power. Test results confirmed the performance of both devices and demonstrated they are capable of achieving the required performance for scientific, defense, industrial, and medical applications.
Low frequency rf current drive
International Nuclear Information System (INIS)
Hershkowitz, N.
1992-01-01
An unshielded antenna for rf heating has been developed and tested during this report period. In addition to design specifications being given, some experimental results are presented utilizing: (1) an unprotected Faraday shield, (2) insulating guard limiters, (3) unshielded antenna experiments, (4) method for detecting small rf driven currents, (5) rf fast wave current drive experiments, (6) alfven wave interactions with electrons, and (7) machine conditioning, impurity generation and density control
Optimizing RF energy transport : channel modelling and transmit antenna and rectenna design
Visser, H.J.
2012-01-01
For powering wireless sensors in buildings rechargeable batteries may be used, being charged remotely by dedicated RF sources. RF energy transport suffers from path loss and therefore the RF power available on a rectenna will be very low. As a consequence, the RF-to-DC conversion efficiency will
Energy Technology Data Exchange (ETDEWEB)
Jiang, Caichao; Hu, Chundong [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Graduate school, University of Science and Technology of China, Hefei 230026 (China); Wei, Jianglong, E-mail: jlwei@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Xie, Yahong; Xu, Yongjian; Liang, Lizhen; Chen, Shiyong; Liu, Sheng; Liu, Zhimin; Xie, Yuanlai [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)
2017-04-15
Highlights: • A supporting power supply system was designed in details for a RF-driven prototype negative ion source at ASIPP. • The RF power supply for plasma generation adopts an all-solid-state power supply structure. • The extraction grid power supply adopts the pulse step modulator (PSM) technology. - Abstract: In order to study the generation and extraction of negative ions for neutral beam injection application, a prototype RF-driven negative ion source and the corresponding test bed are under construction at Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). The target of the negative ion source is extracting a negation ion beam of 350 A/m{sup 2} for 3600 s plasma duration and 100 s beam duration. According to the required parameters of test bed, the design of power supply system is put forward for earlier study. In this paper, the performance requirements and design schemes of RF power supply for plasma generation, impedance matching network, bias voltage power supply, and extraction voltage power supply for negative beam extraction are introduced in details. The schemes provide a reference for the construction of power supply system and lay a foundation for the next phase of experimental operation.
Multi-layered dielectric cladding plasmonic microdisk resonator filter and coupler
International Nuclear Information System (INIS)
Han Cheng, Bo; Lan, Yung-Chiang
2013-01-01
This work develops the plasmonic microdisk filter/coupler, whose effectiveness is evaluated by finite-difference time-domain simulation and theoretical analyses. Multi-layer dielectric cladding is used to prevent the scattering of surface plasmons (SPs) from a silver microdisk. This method allows devices that efficiently perform filter/coupler functions to be developed. The resonant conditions and the effective refractive index of bounded SP modes on the microdisk are determined herein. The waveguide-to-microdisk distance barely influences the resonant wavelength but it is inversely related to the bandwidth. These findings are consistent with predictions made using the typical ring resonator model.
Study of a superconducting spoke-type cavity and of its associated power coupler
International Nuclear Information System (INIS)
Mielot, Ch.
2004-12-01
This work deals with the study of a spoke-type cavity and its associated power coupler. The results of this study are used in the framework of the high power proton linear accelerator of the experimental accelerator-driven system project (XADS). The cavity (F=352 MHz, β=0.35) was tested at 4 K and 2 K. The results at 4 K gave good margins toward XADS requirements that increase the reliability of a spoke based driver. At 2 K the accelerating field reached is the highest in the world for spoke cavities: 16 MV/M. The position and diameter of the coupling have been optimized in order to decrease the HF losses and avoid multi-factor risk. In order to decrease HF losses (taking into account the 20 kW power fed into the cavity) the electric coupling mode has been chosen. Different types of ceramic windows have been studied in order to make this critical point of the coupler reliable: coaxial disk with or without chokes or empty coaxial cylinder. The optimization process focused on the reflected power, the losses in the ceramic and the surface electric field. The risk with chokes has been modeled and studied with the propagation lines theory. A systematic study of the different windows has been done regarding the geometrical parameters. The disk without chokes seems to be a good solution for our application. The power source will be a solid state amplifier (for reliability and modularity reasons). An all over coaxial coupler can be designed and will be fabricated and tested soon. (author)
Electron Source based on Superconducting RF
Xin, Tianmu
High-bunch-charge photoemission electron-sources operating in a Continuous Wave (CW) mode can provide high peak current as well as the high average current which are required for many advanced applications of accelerators facilities, for example, electron coolers for hadron beams, electron-ion colliders, and Free-Electron Lasers (FELs). Superconducting Radio Frequency (SRF) has many advantages over other electron-injector technologies, especially when it is working in CW mode as it offers higher repetition rate. An 112 MHz SRF electron photo-injector (gun) was developed at Brookhaven National Laboratory (BNL) to produce high-brightness and high-bunch-charge bunches for electron cooling experiments. The gun utilizes a Quarter-Wave Resonator (QWR) geometry for a compact structure and improved electron beam dynamics. The detailed RF design of the cavity, fundamental coupler and cathode stalk are presented in this work. A GPU accelerated code was written to improve the speed of simulation of multipacting, an important hurdle the SRF structure has to overcome in various locations. The injector utilizes high Quantum Efficiency (QE) multi-alkali photocathodes (K2CsSb) for generating electrons. The cathode fabrication system and procedure are also included in the thesis. Beam dynamic simulation of the injector was done with the code ASTRA. To find the optimized parameters of the cavities and beam optics, the author wrote a genetic algorithm Python script to search for the best solution in this high-dimensional parameter space. The gun was successfully commissioned and produced world record bunch charge and average current in an SRF photo-injector.
Venous coupler use for free-flap breast reconstructions: specific analyses of TMG and DIEP flaps.
Bodin, Frédéric; Brunetti, Stefania; Dissaux, Caroline; Erik, A Sauleau; Facca, Sybille; Bruant-Rodier, Catherine; Liverneaux, Philippe
2015-05-01
The purpose of this report was to present the results of comparisons of anastomotic data and flap complications in the use of venous coupler in breast reconstruction with the transverse musculocutaneous gracilis (TMG) flap and the deep inferior epigastric perforator (DIEP) flap. Over a three-year period, 95 patients suffering from breast cancer were treated with mastectomy and breast reconstruction using free flaps. We performed 121 mechanical venous anastomoses for 105 flap procedures (80 DIEP and 25 TMG). The coupler size, anastomotic duration, number of anastomoses and postoperative complications were assessed for the entire series. The coupling device was perfectly suitable for all end-to-end anastomoses between the vein(s) of the flap and the internal mammary vein(s). No venous thrombosis occurred. The mean anastomotic time did not significantly differ between the DIEP (330 seconds) and TMG flap procedures (352 seconds) (P = 0.069). Additionally, there were no differences in coupling time observed following a comparison of seven coupler sizes (P = 0.066). The mean coupler size used during the TMG flap procedure was smaller than that used with the DIEP (2.4 mm versus 2.8 mm) (P TMG flap (28%) than with the DIEP flap (11%). The coupler size used was smaller for the TMG procedure and when double venous anastomosis was performed. Additionally, anastomotic time was not affected by the flap type or coupler size used or by anastomosis number. © 2014 Wiley Periodicals, Inc.
New developments in RF power sources
International Nuclear Information System (INIS)
Miller, R.H.
1994-06-01
The most challenging rf source requirements for high-energy accelerators presently being studied or designed come from the various electron-positron linear collider studies. All of these studies except TESLA (the superconducting entry in the field) have specified rf sources with much higher peak powers than any existing tubes at comparable high frequencies. While circular machines do not, in general, require high peak power, the very high luminosity electron-positron rings presently being designed as B factories require prodigious total average rf power. In this age of energy conservation, this puts a high priority on high efficiency for the rf sources. Both modulating anodes and depressed collectors are being investigated in the quest for high efficiency at varying output powers
Review of pulsed rf power generation
International Nuclear Information System (INIS)
Lavine, T.L.
1992-04-01
I am going to talk about pulsed high-power rf generation for normal-conducting electron and positron linacs suitable for applications to high-energy physics in the Next Linear Collider, or NLC. The talk will cover some basic rf system design issues, klystrons and other microwave power sources, rf pulse-compression devices, and test facilities for system-integration studies
Rectifier Design Challenges for RF Wireless Power Transfer and Energy Harvesting Systems
Directory of Open Access Journals (Sweden)
A. Collado
2017-06-01
Full Text Available The design of wireless power transfer (WPT and energy harvesting (EH solutions poses different challenges towards achieving maximum RF-DC conversion efficiency in these systems. This paper covers several selected challenges when developing WPT and electromagnetic EH solutions, such as the design of multiband and broadband rectifiers, the minimization of the effect that load and input power variations may have on the system performance and finally the most optimum power combining mechanisms that can be used when dealing with multi-element rectifiers.
Physics design of APT linac with normal conducting rf cavities
International Nuclear Information System (INIS)
Nath, S.; Billen, J.H.; Stovall, J.E.; Takeda, Harunori; Young, L.M.
1996-01-01
The accelerator based production of tritium calls for a high-power, cw proton linac. Previous designs for such a linac use a radiofrequency quadrupole (RFQ), followed by a drift-tube linac (DTL) to an intermediate energy and a coupled-cavity linc (CCL) to the final energy. The Los Alamos design uses a high-energy (6.7 MeV) RFQ followed by the newly developed coupled-cavity drift-tube linac (CCDTL) and a CCL. This design accommodates external electromagnetic quadrupole lenses which provide a strong uniform focusing lattice from the end of the RFQ to the end of the CCL. The cell lengths in linacs of traditional design are typically graded as a function of particle velocity. By making groups of cells symmetric in both the CCDTL and CCL, the cavity design as well as mechanical design and fabrication is simplified without compromising the performance. At higher energies, there are some advantages of using superconducting rf cavities. Currently, such schemes are under vigorous study. This paper describes the linac design based on normal conducting cavities and presents simulation results
InGaN directional coupler made with a one-step etching technique
Gao, Xumin; Yuan, Jialei; Yang, Yongchao; Zhang, Shuai; Shi, Zheng; Li, Xin; Wang, Yongjin
2017-06-01
We propose, fabricate and characterize an on-chip integration of light source, InGaN waveguide, directional coupler and photodiode, in which AlGaN layers are used as top and bottom optical claddings to form an InGaN waveguide for guiding the in-plane emitted light from the InGaN/GaN multiple-quantum-well light-emitting diode (MQW-LED). The difference in etch rate caused by different exposure windows leads to an etching depth discrepancy using the one-step etching technique, which forms the InGaN directional coupler with the overlapped underlying slab. Light propagation results directly confirm effective light coupling in the InGaN directional coupler, which is achieved through high-order guided modes. The InGaN waveguide couples the modulated light from the InGaN/GaN MQW-LED and transfers part of light to the coupled waveguide via the InGaN directional coupler. The in-plane InGaN/GaN MQW-photodiode absorbs the guided light by the coupled InGaN waveguide and induces the photocurrent. The on-chip InGaN photonic integration experimentally demonstrates an in-plane light communication with a data transmission of 50 Mbps.
CW all optical self switching in nonlinear chalcogenide nano plasmonic directional coupler
Motamed-Jahromi, Leila; Hatami, Mohsen
2018-04-01
In this paper we obtain the coupling coefficient of plasmonic directional coupler (PDC) made up of two parallel monolayer waveguides filled with high nonlinear chalcogenide material for TM mode in continues wave (CW) regime. In addition, we assume each waveguides acts as a perturbation to other waveguide. Four nonlinear-coupled equations are derived. Transfer distances are numerically calculated and used for deriving length of all optical switch. The length of designed switch is in the range of 10-1000 μm, and the switching power is in the range of 1-100 W/m. Obtained values are suitable for designing all optical elements in the integrated optical circuits.
Fiber-optic couplers as displacement sensors
Baruch, Martin C.; Gerdt, David W.; Adkins, Charles M.
2003-04-01
We introduce the novel concept of using a fiber-optic coupler as a versatile displacement sensor. Comparatively long fiber-optic couplers, with a coupling region of approximately 10 mm, are manufactured using standard communication SM fiber and placed in a looped-back configuration. The result is a displacement sensor, which is robust and highly sensitive over a wide dynamic range. This displacement sensor resolves 1-2 μm over distances of 1-1.5 mm and is characterized by the essential absence of a 'spring constant' plaguing other strain gauge-type sensors. Consequently, it is possible to couple to extremely weak vibrations, such as the skin displacement affected by arterial heart beat pulsations. Used as a wrist-worn heartbeat monitor, the fidelity of the arterial pulse signal has been shown to be so high that it is possible to not only determine heartbeat and breathing rates, but to implement a new single-point blood pressure measurement scheme which does not squeeze the arm. In an application as a floor vibration sensor for the non-intrusive monitoring of independently living elderly, the sensor has been shown to resolve the distinct vibration spectra of different persons and different events.
Design of a 5 GHz window in a lower hybrid r.f. system
International Nuclear Information System (INIS)
Maebara, S.; Ikeda, Y.; Seki, M.; Imai, T.
1995-01-01
A new pill-box window at a frequency of 5GHz, which has an oversized length in both the axial and the radial direction, has been designed to reduce the r.f. power density and the electric field strength at the ceramics. The dimension of the new pill-box is optimized from the numerical calculation and a voltage standing-wave ratio of less than 1.02 is obtained. The r.f. power density and the maximum electric field strength are reduced to about 40% and 66% of the standard pill-box window respectively. It is evaluated that the power capability of the new oversized pill-box window by cooling edge of ceramics is more than 500kW with continuous-wave operation. ((orig.))
Setsompop, Kawin; Alagappan, Vijayanand; Gagoski, Borjan; Witzel, Thomas; Polimeni, Jonathan; Potthast, Andreas; Hebrank, Franz; Fontius, Ulrich; Schmitt, Franz; Wald, Lawrence L; Adalsteinsson, Elfar
2008-12-01
Slice-selective RF waveforms that mitigate severe B1+ inhomogeneity at 7 Tesla using parallel excitation were designed and validated in a water phantom and human studies on six subjects using a 16-element degenerate stripline array coil driven with a butler matrix to utilize the eight most favorable birdcage modes. The parallel RF waveform design applied magnitude least-squares (MLS) criteria with an optimized k-space excitation trajectory to significantly improve profile uniformity compared to conventional least-squares (LS) designs. Parallel excitation RF pulses designed to excite a uniform in-plane flip angle (FA) with slice selection in the z-direction were demonstrated and compared with conventional sinc-pulse excitation and RF shimming. In all cases, the parallel RF excitation significantly mitigated the effects of inhomogeneous B1+ on the excitation FA. The optimized parallel RF pulses for human B1+ mitigation were only 67% longer than a conventional sinc-based excitation, but significantly outperformed RF shimming. For example the standard deviations (SDs) of the in-plane FA (averaged over six human studies) were 16.7% for conventional sinc excitation, 13.3% for RF shimming, and 7.6% for parallel excitation. This work demonstrates that excitations with parallel RF systems can provide slice selection with spatially uniform FAs at high field strengths with only a small pulse-duration penalty. (c) 2008 Wiley-Liss, Inc.
International Nuclear Information System (INIS)
Pande, Manjiri; Shrotriya, Sandip; Patel, Niranjan
2015-01-01
The important technology development for ion accelerators of 'accelerator driven sub critical reactor system (ADS) is being done under the program of Department of Atomic Energy (DAE). In BARC (BARC) of DAE, technology development of 400 keV radio frequency quadrupole (RFQ) accelerator is done and a 20 MeV - low energy high intensity proton accelerator (LEHIPA) is under development. A 400 KeV deuteron RFQ accelerator is already developed at BARC and its 60 kW radio frequency (RF) power system required for beam acceleration has been designed, developed and tested both in CW mode and in pulse mode for full power of 60 leW. It has been successfully integrated with RFQ via 6-1/8'', 50 ohm RF transmission line, to accelerate proton beam up to 200 KeV energy and deuteron beam to 400 KeV energy. LEHIPA requires about 3 MW of RF power for its operation. So, three 1 MW, 352 MHz RF systems based on klystron will be developed for RFQ and two DTLs. The klystron based RF system for 3 MeV RFQ is under commissioning. Its various subsystems like energy less and insulated gate bipolar transistor (IGBT) based high voltage and low voltage bias supplies, a critical and fast protection and control system - handling various types of field signals, fast acting hard wired instrumentation circuits for critical signals, 100 kV crowbar with its circuits, pulsing circuits and RF circuits have been successfully designed, developed and integrated with klystron. Latest technology development of solid state RF amplifiers at 325 MHz and 350 MHz for normal and super conducting accelerators has attained a certain power level. This paper will discuss all these high power RF systems in detail. (author)
RF Design of the TW Buncher for the CLIC Drive Beam Injector (2nd report)
Shaker, Hamed
2016-01-01
CLIC is based on the two beams concept that one beam (drive beam) produces the required RF power to accelerate another beam (main beam). The drive beam is produced and accelerated up to 50MeV inside the CLIC drive beam injector. The drive beam injector main components are a thermionic electron gun, three sub-harmonic bunchers, a pre-buncher, a TW buncher, 13 accelerating structures and one magnetic chicane. This document is the second report of the RF structure design of the TW buncher. This design is based on the beam dynamic design done by Shahin Sanaye Hajari due to requirements mentioned in CLIC CDR. A disk-loaded tapered structure is chosen for the TW buncher. The axial electric field increases strongly based on the beam dynamic requirements. This second report includes the study of HOM effects, retuning the cells, study of dimensional tolerances and the heat dissipation on the surface.
Design and modeling of a 17 GHz photocathode RF gun
International Nuclear Information System (INIS)
Lin, C.L.; Chen, S.C.; Wurtele, J.S.; Temkin, R.; Danly, B.
1991-01-01
The performance of a high-frequency (17 GHz), high accelerating gradient (250 MV/m) photocathode RF gun is studied with the particle-in-cell code MAGIC. For the parameter regime of interest, i.e. bunch charge smaller than 1 nC and bunch length shorter than 2 ps, space-charge forces and finite bunch length effects are less significant in determining the beam quality than nonlinear RF forces are. The cavity geometry, RF phase for photoemission, cathode size, and current density are being optimized to obtain high quality beams. Preliminary results are presented
Broadband direct RF digitization receivers
Jamin, Olivier
2014-01-01
This book discusses the trade-offs involved in designing direct RF digitization receivers for the radio frequency and digital signal processing domains. A system-level framework is developed, quantifying the relevant impairments of the signal processing chain, through a comprehensive system-level analysis. Special focus is given to noise analysis (thermal noise, quantization noise, saturation noise, signal-dependent noise), broadband non-linear distortion analysis, including the impact of the sampling strategy (low-pass, band-pass), analysis of time-interleaved ADC channel mismatches, sampling clock purity and digital channel selection. The system-level framework described is applied to the design of a cable multi-channel RF direct digitization receiver. An optimum RF signal conditioning, and some algorithms (automatic gain control loop, RF front-end amplitude equalization control loop) are used to relax the requirements of a 2.7GHz 11-bit ADC. A two-chip implementation is presented, using BiCMOS and 65nm...
Design considerations for RF power amplifiers demonstrated through a GSM/EDGE power amplifier module
Baltus, P.G.M.; Bezooijen, van A.; Huijsing, J.H.; Steyaert, M.; Roermund, van A.H.M.
2002-01-01
This paper describes the design considerations for RF power amplifiers in general, including trends in systems, linearity and efficiency, the PA environment, implementation is sues and technology. As an example a triple-band (900/1800/1900MHz) dual mode (GSMIEdge) power amplifier module is described
A linear accelerator power amplification system for high gradient structure research
International Nuclear Information System (INIS)
Haimson, J.; Mecklenburg, B.
1999-01-01
The ongoing development of linear collider high power RF sources and pulse compression systems has resulted in substantial progress towards a goal of providing a peak RF power level of approximately 250 MW at the input of the accelerator structure. While the immediate development and the high power testing of specialized waveguide components required for power transmission at these high levels have proceeded expeditiously due to the availability of resonant ring systems, the testing of high gradient accelerator structures at very high power levels, and the investigation of coupler cavity RF breakdown problems have, typically, been curtailed due to the unavailability of suitable 200 to 300 MW RF test facilities. We describe herein a compact, high peak power amplification system based on a dual hybrid bridge configuration that avoids the need for power splitters at the accelerator dual feed couplers, and also provides a convenient interface for installing high gradient accelerator test structures. Design parameters are presented for a proposed power amplification system that makes use of a 75 MW, 1/2 μs flat-top RF source to produce 280 MW, 1/4 μs flat-top power for testing dual feed TW experimental accelerator sections
Sun, Guilin; Muneer, Badar; Li, Ying; Zhu, Qi
2018-04-01
This paper presents an ultracompact design of biomedical implantable devices with integrated wireless power transfer (WPT) and RF transmission capabilities for implantable medical applications. By reusing the spiral coil in an implantable device, both RF transmission and WPT are realized without the performance degradation of both functions in ultracompact size. The complete theory of WPT based on magnetic resonant coupling is discussed and the design methodology of an integrated structure is presented in detail, which can guide the design effectively. A system with an external power transmitter and implantable structure is fabricated to validate the proposed approach. The experimental results show that the implantable structure can receive power wirelessly at 39.86 MHz with power transfer efficiency of 47.2% and can also simultaneously radiate at 2.45 GHz with an impedance bandwidth of 10.8% and a gain of -15.71 dBi in the desired direction. Furthermore, sensitivity analyses are carried out with the help of experiment and simulation. The results reveal that the system has strong tolerance to the nonideal conditions. Additionally, the specific absorption rate distribution is evaluated in the light of strict IEEE standards. The results reveal that the implantable structure can receive up to 115 mW power from an external transmitter and radiate 6.4 dB·m of power safely.
Wintucky, Edwin G.; Simons, Rainee N.
2015-01-01
This paper presents the design, fabrication and test results for a novel waveguide multimode directional coupler (MDC). The coupler, fabricated from two dissimilar frequency band waveguides, is capable of isolating power at the second harmonic frequency from the fundamental power at the output port of a traveling-wave tube (TWT) amplifier. Test results from proof-of-concept demonstrations are presented for a Ku-band/Ka-band MDC and a Ka-band/E-band MDC. In addition to power measurements at harmonic frequencies, a potential application of the MDC is in the design of a satellite borne beacon source for atmospheric propagation studies at millimeter-wave (mm-wave) frequencies (Ka-band and E-band).
Rf and space-charge induced emittances in laser-driven rf guns
International Nuclear Information System (INIS)
Kim, Kwang-Je; Chen, Yu-Jiuan.
1988-10-01
Laser-driven rf electron guns are potential sources of high-current, low-emittance, short bunch-length electron beams, which are required for many advanced accelerator applications, such as free-electron lasers and injectors for high-energy machines. In such guns the design of which was pioneered at Los Alamos National Laboratory and which is currently being developed at several other laboratories, a high-power laser beam illuminates a photo-cathode surface placed on an end wall of an rf cavity. The main advantages of this type of gun are that the time structure of the electron beam is controlled by the laser, eliminating the need for bunchers, and that the electric field in rf cavities can be made very strong, so that the effects due to space-charge repulsion can be minimized. In this paper, we present an approximate but simple analysis for the transverse and longitudinal emittances in rf guns that takes into account both the time variation of the rf field and the space-charge effect. The results are compared and found to agree well with those from simulation. 7 refs., 6 figs
An updated overview of the LEB RF system
International Nuclear Information System (INIS)
Rogers, J.D.; Ferrell, J.H.; Curbow, J.E.; Friedrichs, C.
1992-01-01
Each of the Low Energy Booster (LEB) rf systems consists of the following major subsystems: a vacuum tube final rf amplifier driven by a solid state rf amplifier, a ferrite-tuned rf cavity used to bunch and accelerate the beam, a low-level rf system including rf feedback systems, a computer-based supervisory control system, and associated power supplies. The LEB rf system is broadband with the exception of the rf cavity, which is electronically tuned from approximately 47.5 MHz to 59.7 MHz in 50 ms. The design and development status of the LEB rf system is presented, with particular emphasis on the cavity and tuner, and the tuner bias power supply
Bessel-function analysis of the optimized star coupler for uniform power splitting.
Song, G Hugh; Park, Mahn Yong
2004-08-01
An optimized N x N planar optic star coupler that utilizes directional coupling of arrayed waveguides for uniform power splitting is analyzed on the basis of special properties of the involved Bessel-function series. The analysis has provided a remarkably simple, novel basic design formula for such a device with much needed physical insights into the unique diffraction properties. For the analysis of diffraction from the end of directionally coupled arrayed waveguides, many useful formulas around the Bessel functions, such as the addition theorem and the Kepler-Bessel series, have been given in new forms.
Design and research of RF system for 10 MeV compact cyclotron
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
A 10 MeV compact cyclotron (CYCHU-10) has been developing in Huazhong University of Science and Technology (HUST). The RF system includes a 10 kW RF power generator and a resonance cavity. There is no automatic frequency tuning equipment in the cavity due to space limitations, so the generator must search and track the cavity resonant frequency. AD9850 synthesizer is used to generate RF signal in the experimental prototype, and a fine sinusoidal waveform around 99 MHz is obtained with the method of picking up a special aliased signal from the synthesizer’s output, and the output power level can be set by regulating the resistor connected to the Pin ’Rset’. The final stage amplifier based on tetrode operates in the grounded cathode configuration, and the schematic of the tetrode circuit is illustrated. The method of searching the resonant frequency is discussed in detail. For the sake of a compact and robust structure, the resonance cavity will adopt non-uniform characteristic impedance coaxial structure, and the magnet surface electroplated with copper will be used as dummy Dees. The precise shapes and dimensions of the cavity are designed and simulation results are carried out in this paper. The distributions of electromagnetic field are illustrated by means of numerical calculation analysis, and the wooden model test is preformed as well.
International Nuclear Information System (INIS)
Cole, Michael; Kneisel, Peter; Ben-Zvi, Ilan; Burrill, Andrew; Hahn, H.; Rao, Triveni; Zhao, Y.
2005-01-01
Over the past several years Advanced Energy Systems and BNL have been collaborating on the development and testing of a fully superconducting photocathode electron gun. Over the past year we have begun to realize significant results which have been published elsewhere (1). This paper will review the RF design of the gun under test and present results of its performance under various operating conditions. Results for cavity quality factor will be presented for various operating temperatures and cavity field gradients. We will also discuss future plans for testing using this gun.
International Nuclear Information System (INIS)
Alicia Hofler; Pavel Evtushenko
2007-01-01
Injector gun design is an iterative process where the designer optimizes a few nonlinearly interdependent beam parameters to achieve the required beam quality for a particle accelerator. Few tools exist to automate the optimization process and thoroughly explore the parameter space. The challenging beam requirements of new accelerator applications such as light sources and electron cooling devices drive the development of RF and SRF photo injectors. A genetic algorithm (GA) has been successfully used to optimize DC photo injector designs at Cornell University [1] and Jefferson Lab [2]. We propose to apply GA techniques to the design of RF and SRF gun injectors. In this paper, we report on the initial phase of the study where we model and optimize a system that has been benchmarked with beam measurements and simulation
Ultra-High-Efficiency Apodized Grating Coupler Using a Fully Etched Photonic Crystal
DEFF Research Database (Denmark)
Ding, Yunhong; Peucheret, Christophe; Ou, Haiyan
2013-01-01
We demonstrate an apodized fiber-to-chip grating coupler using fully etched photonic crystal holes on the silicon-on-insulator platform. An ultra-high coupling efficiency of 1.65 dB (68%) with 3 dB bandwidth of 60 nm is experimentally demonstrated.......We demonstrate an apodized fiber-to-chip grating coupler using fully etched photonic crystal holes on the silicon-on-insulator platform. An ultra-high coupling efficiency of 1.65 dB (68%) with 3 dB bandwidth of 60 nm is experimentally demonstrated....
Design and numerical optimization of a mode multiplexer based on few-mode fiber couplers
International Nuclear Information System (INIS)
Xie, Yiwei; Fu, Songnian; Liu, Hai; Zhang, Hailiang; Tang, Ming; Liu, Deming; Shum, P
2013-01-01
Mode division multiplexing (MDM) transmission based on few-mode fibers (FMFs) appears to be an alternative solution for overcoming the capacity limit of single-mode fibers (SMFs). A FMF coupler-based mode division multiplexer/demultiplexer (MMUX/DeMMUX) is proposed and theoretically investigated after the fabricated FMF is characterized. MMUXs/DeMMUXs with a mode contrast ratio (MCR) of more than 20 dB can be obtained for two-mode multiplexing and three-mode multiplexing over a wavelength span of 60 and 10 nm, respectively. We numerically verify the proposed MMUX/DeMMUX which has the advantages of high MCR, easy fabrication and maintenance, and low wavelength dependence. (paper)
Computer-aided design of the RF-cavity for a high-power S-band klystron
Kant, D.; Bandyopadhyay, A. K.; Pal, D.; Meena, R.; Nangru, S. C.; Joshi, L. M.
2012-08-01
This article describes the computer-aided design of the RF-cavity for a S-band klystron operating at 2856 MHz. State-of-the-art electromagnetic simulation tools SUPERFISH, CST Microwave studio, HFSS and MAGIC have been used for cavity design. After finalising the geometrical details of the cavity through simulation, it has been fabricated and characterised through cold testing. Detailed results of the computer-aided simulation and cold measurements are presented in this article.
Iannacci, Jacopo
2013-01-01
Closes the gap between hardcore-theoretical and purely experimental RF-MEMS books. The book covers, from a practical viewpoint, the most critical steps that have to be taken in order to develop novel RF-MEMS device concepts. Prototypical RF-MEMS devices, both including lumped components and complex networks, are presented at the beginning of the book as reference examples, and these are then discussed from different perspectives with regard to design, simulation, packaging, testing, and post-fabrication modeling. Theoretical concepts are introduced when necessary to complement the practical
RF current distribution and topology of RF sheath potentials in front of ICRF antennae
International Nuclear Information System (INIS)
Colas, L.; Heuraux, S.; Bremond, S.; Bosia, G.
2005-01-01
The 2D (radial/poloidal) spatial topology of RF-induced convective cells developing radially in front of ion cyclotron range of frequency (ICRF) antennae is investigated, in relation to the spatial distribution of RF currents over the metallic structure of the antenna. This is done via a Green's function, determined from the ICRF wave coupling equations, and well-suited to open field lines extending toroidally far away on both sides of the antenna. Using such formalism, combined with a full-wave calculation using the 3D antenna code ICANT (Pecoul S. et al 2000 Comput. Phys. Commun. 146 166-87), two classes of convective cells are analysed. The first one appears in front of phased arrays of straps, and depending on the strap phasing, its topology is interpreted using the poloidal profiles of either the RF current or the RF voltage of the strip line theory. The other class of convective cells is specific to antenna box corners and is evidenced for the first time. Based on such analysis, general design rules are worked out in order to reduce the RF-sheath potentials, which generalize those proposed in the earlier literature, and concrete antenna design options are tested numerically. The merits of aligning all strap centres on the same (tilted) flux tube, and of reducing the antenna box toroidal conductivity in its lower and upper parts, are discussed
Design of RF energy harvesting platforms for power management unit with start-up circuits
Costanzo, Alessandra; Masotti, Diego
2013-12-01
In this contribution we discuss an unconventional rectifier design dedicated to RF energy harvesting from ultra-low sources, such as ambient RF sources which are typically of the order of few to few tens of μW. In such conditions unsuccessful results may occur if the rectenna is directly connected to its actual load since either the minimum power or the minimum activation voltage may not be simultaneously available. For this reason a double-branch rectifier topology is considered for the power management unit (PMU), instead of traditional single-branch one. The new PMU, interposed between the rectenna and application circuits, allows the system to operate with significantly lower input power with respect to the traditional solution, while preserving efficiency during steady-state power conversion.
Design of RF energy harvesting platforms for power management unit with start-up circuits
International Nuclear Information System (INIS)
Costanzo, Alessandra; Masotti, Diego
2013-01-01
In this contribution we discuss an unconventional rectifier design dedicated to RF energy harvesting from ultra-low sources, such as ambient RF sources which are typically of the order of few to few tens of μW. In such conditions unsuccessful results may occur if the rectenna is directly connected to its actual load since either the minimum power or the minimum activation voltage may not be simultaneously available. For this reason a double-branch rectifier topology is considered for the power management unit (PMU), instead of traditional single-branch one. The new PMU, interposed between the rectenna and application circuits, allows the system to operate with significantly lower input power with respect to the traditional solution, while preserving efficiency during steady-state power conversion
RF system considerations for large high-duty-factor linacs
International Nuclear Information System (INIS)
Lynch, M.T.; Ziomek, C.D.; Tallerico, P.J.; Regan, A.H.; Eaton, L.; Lawrence, G.
1994-01-01
RF systems are often a major cost item for linacs, but this is especially true for large high-duty-factor linacs (up to and including CW) such as the Accelerator for Production of Tritium (APT) or the Accelerator for Transmutation of nuclear Waste (ATW). In addition, the high energy and high average beam current of these machines (approximately 1 GeV, 100--200 mA) leads to a need for excellent control of the accelerating fields in order to minimize the possibility of beam loss in the accelerator and the resulting activation. This paper will address the key considerations and limitations in the design of the RF system. These considerations impact the design of both the high power RF components and the RF controls. As might be expected, the two concerns sometimes lead to conflicting design requirements. For example minimum RF operating costs lead to a desire for operation near saturation of the high power RF generators in order to maximize the operating efficiency. Optimal control of the RF fields leads to a desire for maximum overdrive capability in those same generators in order to respond quickly to disturbances of the accelerator fields
Detailed design of the RF source for the 1 MV neutral beam test facility
International Nuclear Information System (INIS)
Marcuzzi, D.; Palma, M. Dalla; Pavei, M.; Heinemann, B.; Kraus, W.; Riedl, R.
2009-01-01
In the framework of the EU activities for the development of the Neutral Beam Injector for ITER, the detailed design of the Radio Frequency (RF) driven negative ion source to be installed in the 1 MV ITER Neutral Beam Test Facility (NBTF) has been carried out. Results coming from ongoing R and D on IPP test beds [A. Staebler et al., Development of a RF-Driven Ion Source for the ITER NBI System, this conference] and the design of the new ELISE facility [B. Heinemann et al., Design of the Half-Size ITER Neutral Beam Source Test Facility ELISE, this conference] brought several modifications to the solution based on the previous design. An assessment was carried out regarding the Back-Streaming positive Ions (BSI+) that impinge on the back plates of the ion source and cause high and localized heat loads. This led to the redesign of most heated components to increase cooling, and to different choices for the plasma facing materials to reduce the effects of sputtering. The design of the electric circuit, gas supply and the other auxiliary systems has been optimized. Integration with other components of the beam source has been revised, with regards to the interfaces with the supporting structure, the plasma grid and the flexible connections. In the paper the design will be presented in detail, as well as the results of the analyses performed for the thermo-mechanical verification of the components.
Series-Tuned High Efficiency RF-Power Amplifiers
DEFF Research Database (Denmark)
Vidkjær, Jens
2008-01-01
An approach to high efficiency RF-power amplifier design is presented. It addresses simultaneously efficiency optimization and peak voltage limitations when transistors are pushed towards their power limits.......An approach to high efficiency RF-power amplifier design is presented. It addresses simultaneously efficiency optimization and peak voltage limitations when transistors are pushed towards their power limits....
Design study on an independently-tunable-cells thermionic RF gun
International Nuclear Information System (INIS)
Hama, H.; Tanaka, T.; Hinode, F.; Kawai, M.
2006-01-01
Characteristics of a thermionic RF gun have been studied by a 3-D simulation code developed using an FDTD (Finite Difference Time Domain) method as a Maxwell's equations solver. The gun is consists of two independent power feeding cavities, so that we call it independently-tunable-cells (ITC)'-RF gun. The first cell is the cathode cell and the second one is an accelerating cell. The ITC gun can be operated at various modes of different RF-power ratio and phase between two cavities. Simulation study shows a velocity-bunching like effect may be occurred in the gun, so that the short pulse beam from the thermionic RF gun is a better candidate to produce the coherent THz synchrotron radiation. Expected bunch length with a total charge of ∼20 pC (1% energy width from the top energy) is around 200 fs (fwhm). Even the beam energy extracted from the gun is varied by which the input powers are changed, almost same shape of the longitudinal phase space can be produced by tuning the phase. (author)
Surface acoustic waves voltage controlled directional coupler
Golan, G.; Griffel, G.; Yanilov, E.; Ruschin, S.; Seidman, A.; Croitoru, N.
1988-10-01
An important condition for the development of surface wave integrated-acoustic devices is the ability to guide and control the propagation of the acoustic energy. This can be implemented by deposition of metallic "loading" channels on an anisotropic piezoelectric substrate. Deposition of such two parallel channels causes an effective coupling of acoustic energy from one channel to the other. A basic requirement for this coupling effect is the existence of the two basic modes: a symmetrical and a nonsymmetrical one. A mode map that shows the number of sustained modes as a function of the device parameters (i.e., channel width; distance between channels; material velocity; and acoustical exciting frequency) is presented. This kind of map can help significantly in the design process of such a device. In this paper we devise an advanced acoustical "Y" coupler with the ability to control its effective coupling by an externally applied voltage, thereby causing modulation of the output intensities of the signals.
Grenier, Jason R; Fernandes, Luís A; Herman, Peter R
2015-06-29
Precise alignment of femtosecond laser tracks in standard single mode optical fiber is shown to enable controllable optical tapping of the fiber core waveguide light with fiber cladding photonic circuits. Asymmetric directional couplers are presented with tunable coupling ratios up to 62% and bandwidths up to 300 nm at telecommunication wavelengths. Real-time fiber monitoring during laser writing permitted a means of controlling the coupler length to compensate for micron-scale alignment errors and to facilitate tailored design of coupling ratio, spectral bandwidth and polarization properties. Laser induced waveguide birefringence was harnessed for polarization dependent coupling that led to the formation of in-fiber polarization-selective taps with 32 dB extinction ratio. This technology enables the interconnection of light propagating in pre-existing waveguides with laser-formed devices, thereby opening a new practical direction for the three-dimensional integration of optical devices in the cladding of optical fibers and planar lightwave circuits.
International Nuclear Information System (INIS)
Franco, M.A.R.
1991-01-01
In this work, the experimental results pertaining to the construction and evaluation of a constant gradient accelerating structure and of the radiofrequency couplers are presented. The theoretical methods to determine the initial dimensions of the iris-loaded accelerating structure are presented. The final dimensions have been experimentally determined utilizing four three-cavity sections representing the 4 sup(th), 12 sup(th), 20 sup(th) and 27 sup(th) cavities of the final structure. The diameters of the cavities were corrected for variations of temperature, pressure and humidity. A v sub(p) = c, constant gradient, twelve-cavity prototype of the accelerating structure have been constructed and its principal parameters were experimentally determined according to methods also described in this work. Two prototypes of door-knob type radiofrequency couplers have been constructed and experimental procedures to match and tune the couplers and the accelerating structure were implemented. (author)
Directional multimode coupler for planar magnonics: Side-coupled magnetic stripes
Energy Technology Data Exchange (ETDEWEB)
Sadovnikov, A. V., E-mail: sadovnikovav@gmail.com; Nikitov, S. A. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Kotel' nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009 (Russian Federation); Beginin, E. N.; Sheshukova, S. E.; Romanenko, D. V.; Sharaevskii, Yu. P. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation)
2015-11-16
We experimentally demonstrate spin waves coupling in two laterally adjacent magnetic stripes. By the means of Brillouin light scattering spectroscopy, we show that the coupling efficiency depends both on the magnonic waveguides' geometry and the characteristics of spin-wave modes. In particular, the lateral confinement of coupled yttrium-iron-garnet stripes enables the possibility of control over the spin-wave propagation characteristics. Numerical simulations (in time domain and frequency domain) reveal the nature of intermodal coupling between two magnonic stripes. The proposed topology of multimode magnonic coupler can be utilized as a building block for fabrication of integrated parallel functional and logic devices such as the frequency selective directional coupler or tunable splitter, enabling a number of potential applications for planar magnonics.
Development and advances in conventional high power RF systems
International Nuclear Information System (INIS)
Wilson, P.B.
1995-06-01
The development of rf systems capable of producing high peak power (hundreds of megawatts) at relatively short pulse lengths (0.1--5 microseconds) is currently being driven mainly by the requirements of future high energy linear colliders, although there may be applications to industrial, medical and research linacs as well. The production of high peak power rf typically involves four basic elements: a power supply to convert ac from the ''wall plug'' to dc; a modulator, or some sort of switching element, to produce pulsed dc power; an rf source to convert the pulsed dc to pulsed rf power; and possibly an rf pulse compression system to further enhance the peak rf power. Each element in this rf chain from wall plug to accelerating structure must perform with high efficiency in a linear collider application, such that the overall system efficiency is 30% or more. Basic design concepts are discussed for klystrons, modulators and rf pulse compression systems, and their present design status is summarized for applications to proposed linear colliders
RF and microwave microelectronics packaging II
Sturdivant, Rick
2017-01-01
Reviews RF, microwave, and microelectronics assembly process, quality control, and failure analysis Bridges the gap between low cost commercial and hi-res RF/Microwave packaging technologies Engages in an in-depth discussion of challenges in packaging and assembly of advanced high-power amplifiers This book presents the latest developments in packaging for high-frequency electronics. It is a companion volume to “RF and Microwave Microelectronics Packaging” (2010) and covers the latest developments in thermal management, electrical/RF/thermal-mechanical designs and simulations, packaging and processing methods, and other RF and microwave packaging topics. Chapters provide detailed coverage of phased arrays, T/R modules, 3D transitions, high thermal conductivity materials, carbon nanotubes and graphene advanced materials, and chip size packaging for RF MEMS. It appeals to practicing engineers in the electronic packaging and high-frequency electronics domain, and to academic researchers interested in underst...
Federmann, S; Caspers, F
2012-01-01
Different conceptional designs for RF high power loads are presented. One concept implies the use of solid state rectifier modules for direct RF to DC conversion with efficiencies beyond 80%. In addition, robust metallic low-Q resonant structures, capable of operating at high temperatures (>150 ◦C) are discussed. Another design deals with a very high temperature (up to 800 ◦C) air cooled load using a ceramic foam block inside a metal enclosure. This porous ceramic block is the microwave absorber and is not brazed to the metallic enclosure.
Design of traveling wave windows for the PEP-II RF coupling network
International Nuclear Information System (INIS)
Kroll, N.M.; Ng, C.K.; Judkins, J.; Neubauer, M.
1995-05-01
The waveguide windows in the PEP-II RF coupling network have to withstand high power of 500 kW. Traveling wave windows have lower power dissipation than conventional self-matched windows, thus rendering the possibility of less stringent mechanical design. The traveling wave behavior is achieved by providing a reflecting iris on each side of the window, and depending on the configuration of the irises, traveling wave windows are characterized as inductive or capacitive types. A numerical design procedure using MAFIA has been developed for traveling wave windows. The relative advantages of inductive and capacitive windows are discussed. Furthermore, the issues of bandwidth and multipactoring are also addressed
Pozar, David M
2012-01-01
The 4th edition of this classic text provides a thorough coverage of RF and microwave engineering concepts, starting from fundamental principles of electrical engineering, with applications to microwave circuits and devices of practical importance. Coverage includes microwave network analysis, impedance matching, directional couplers and hybrids, microwave filters, ferrite devices, noise, nonlinear effects, and the design of microwave oscillators, amplifiers, and mixers. Material on microwave and RF systems includes wireless communications, radar, radiometry, and radiation hazards. A large
Datta, Shubhashish; Rajagopalan, Sruti; Lemke, Shaun; Joshi, Abhay
2014-06-01
We report a balanced PIN-TIA photoreceiver integrated with a 3 dB fiber coupler for distributed fiber optic sensors. This detector demonstrates -3 dB bandwidth >15 GHz and coupled conversion gain >65 V/W per photodiode through either input port of the 3 dB coupler, and can be operated at local oscillator power of +17 dBm. The combined common mode rejection of the balanced photoreceiver and the integrated 3 dB coupler is >20 dB. We also present measurement results with various optical stimuli, namely impulses, sinusoids, and pseudo-random sequences, which are relevant for time domain reflectometry, frequency domain reflectometry, and code correlation sensors, respectively.
PEP-II RF System Operation and Performance
International Nuclear Information System (INIS)
McIntosh, P.
2005-01-01
The Low Energy Ring (LER) and High Energy Ring (HER) RF systems have operated now on PEP-II since July 1998 and have assisted in breaking all design luminosity records back in June 2001. Luminosity on PEP-II has steadily increased since then as a consequence of larger e+ and e- beam currents being accumulated. This has meant that the RF systems have inevitably been driven harder, not only to achieve these higher stored beam currents, but also to reliably keep the beams circulating whilst at the same time minimizing the number of aborts due to RF system faults. This paper details the current PEP-II RF system configurations for both rings, as well as future upgrade plans spanning the next 3-5 years. Limitations of the current RF system configurations are presented, highlighting improvement projects which will target specific areas within the RF systems to ensure that adequate operating overheads are maintained and reliable operation is assured. The Low Energy Ring (LER) and High Energy Ring (HER) RF systems have operated now on PEP-II since July 1998 and have assisted in breaking all design luminosity records back in June 2001. Luminosity on PEP-II has steadily increased since then as a consequence of larger e+ and e- beam currents being accumulated. This has meant that the RF systems have inevitably been driven harder, not only to achieve these higher stored beam currents, but also to reliably keep the beams circulating whilst at the same time minimizing the number of aborts due to RF system faults. This paper details the current PEP-II RF system configurations for both rings, as well as future upgrade plans spanning the next 3-5 years. Limitations of the current RF system configurations are presented, highlighting improvement projects which will target specific areas within the RF systems to ensure that adequate operating overheads are maintained and reliable operation is assured
Zhang, Li; Wang, Lei; He, Jian-Jun
2009-09-01
A novel design of monolithically integrated diplexers and triplexers for fiber-to-the-home applications is presented. A bilevel etched asymmetrical 2 x 2 optical coupler is analyzed for efficient couplings of both upstream and downstream signals. The design of the diplexer is extended to a triplexer by adding an etched diffraction grating as an additional downstream demultiplexing element. The total size of the integrated diplexer and triplexer is smaller than 500 microm x 500 microm.
Ceramic Power Extractor Design at 15.6 GHz
Smirnov, Alexei Yu; Yi, Rong; Yu, David
2005-01-01
Power extractor and coupler designs developed for an experiment planned at the 12th beam harmonic of the upgraded Advanced Wakefield Accelerator (AWA) facility is described. New features are an upstream HOM dielectric damper with additional tapering, and a single-port coupler considered in two variants. Performance analysis includes coupler geometric tolerances, overvoltage, dipole mode wake and BBU; and wakefield losses induced in the damper.
RF BREAKDOWN STUDIES USING PRESSURIZED CAVITIES
Energy Technology Data Exchange (ETDEWEB)
Johnson, Rolland
2014-09-21
1.3 GHz RF test cell capable of operating both at high pressure and in vacuum with replaceable electrodes was designed, built, and power tested in preparation for testing the frequency and geometry effects of RF breakdown at Argonne National Lab. At the time of this report this cavity is still waiting for the 1.3 GHz klystron to be available at the Wakefield Test Facility. (3) Under a contract with Los Alamos National Lab, an 805 MHz RF test cavity, known as the All-Seasons Cavity (ASC), was designed and built by Muons, Inc. to operate either at high pressure or under vacuum. The LANL project to use the (ASC) was cancelled and the testing of the cavity has been continued under the grant reported on here using the Fermilab Mucool Test Area (MTA). The ASC is a true pillbox cavity that has performed under vacuum in high external magnetic field better than any other and has demonstrated that the high required accelerating gradients for many muon cooling beam line designs are possible. (4) Under ongoing support from the Muon Acceleration Program, microscopic surface analysis and computer simulations have been used to develop models of RF breakdown that apply to both pressurized and vacuum cavities. The understanding of RF breakdown will lead to better designs of RF cavities for many applications. An increase in the operating accelerating gradient, improved reliability and shorter conditioning times can generate very significant cost savings in many accelerator projects.
Directory of Open Access Journals (Sweden)
Hirohisa Yokota
2016-01-01
Full Text Available Fused coupler forming with a single-mode fiber (SMF and a photonic crystal fiber (PCF is one of the solutions for optical coupling from a light source to a PCF. In this paper, we presented coupling characteristics of a fused fiber coupler formed with an ordinary SMF and a PCF having air hole collapsed taper. A prototype of SMF-PCF coupler with air hole collapsed taper was fabricated using CO2 laser irradiation. The coupling efficiency from SMF to PCF was −6.2 dB at 1554 nm wavelength in the fabricated coupler. The structure of the SMF-PCF coupler to obtain high coupling efficiency was theoretically clarified by beam propagation analysis using an equivalent model of the coupler with simplification. It was clarified that appropriately choosing the prestretched or etched SMF diameter and the length of air hole collapsed region was effective to obtain high coupling efficiency that was a result of high extinction ratio at cross port and low excess loss. We also demonstrated that the diameter of prestretched SMF to obtain high coupling efficiency was insensitive to the air hole diameter ratio to pitch of the PCF in the air hole collapsed SMF-PCF coupler.
Structural and dynamic analysis of an ultra short intracavity directional coupler
Gravé, Ilan; Griffel, Giora; Daou, Youssef; Golan, Gadi
1997-01-01
A recently proposed intracavity directional coupler is analysed. Exact analytic expressions for important parameters such as the transmission ratio, the coupling length, and the photon lifetime are given. We show that by controlling the mirror reflectivities of the cavity, it is theoretically possible to reduce the coupling length to a zero limit. The photon lifetime, which governs the dynamic properties of the structure, sets an upper frequency limit of a few hundreds of GHz, which is well over the bandwidth limitation of microwave lumped or travelling wave electrodes. This novel family of intracavity couplers has important applications in the realization of integrated optics circuits for high-speed computing, data processing, and communication.
Superconducting rf and beam-cavity interactions
International Nuclear Information System (INIS)
Bisognano, J.J.
1987-01-01
Beam-cavity interactions can limit the beam quality and current handling capability of linear and circular accelerators. These collective effects include cumulative and regenerative transverse beam breakup (BBU) in linacs, transverse multipass beam breakup in recirculating linacs and microtrons, longitudinal and transverse coupled-bunch instabilities in storage rings, and a variety of transverse and longitudinal single-bunch phenomena (instabilities, beam breakup, and energy deposition). The superconducting radio frequency (SRF) environment has a number of features which distinguish it from room temperature configuration with regard to these beam-cavity interactions. Typically the unloaded Qs of the lower higher order modes (HOM) are at the 10 9 level and require significant damping through couplers. High gradient CW operation, which is a principal advantage of SRF, allows for better control of beam quality, which for its preservation requires added care which respect to collective phenomena. Gradients are significantly higher than those attainable with copper in CW operation but remain significantly lower than those obtainable with pulsed copper cavities. Finally, energy deposition by the beam into the cavity can occur in a cryogenic environment. In this note those characteristics of beam-cavity interactions which are of particular importance for superconducting RF cavities are highlighted. 6 refs., 4 figs
Coaxial TW window for power couplers and multipactor considerations
International Nuclear Information System (INIS)
Hanus, X.; Mosnier, A.
1996-01-01
A Traveling Wave coaxial window has been studied for power couplers purposes. The main features, a reduced electrical field in the ceramic and its multipacting free shape are presented. Multipacting simulations results for other window geometries, using a conical or a cylindrical ceramic are also showed. (author)
Visser, H.J.; Pop, V.; Op het Veld, J.H.G.; Vullers, R.J.M.
2011-01-01
The design of a remote RF battery charger is discussed through the analysis and design of the subsystems of a rectenna (rectifying antenna): antenna, rectifying circuit and loaded DC-to-DC voltage (buck-boost) converter. Optimum system power generation performance is obtained by adopting a system
Water cooling of RF structures
International Nuclear Information System (INIS)
Battersby, G.; Zach, M.
1994-06-01
We present computer codes for heat transfer in water cooled rf cavities. RF parameters obtained by SUPERFISH or analytically are operated on by a set of codes using PLOTDATA, a command-driven program developed and distributed by TRIUMF [1]. Emphasis is on practical solutions with designer's interactive input during the computations. Results presented in summary printouts and graphs include the temperature, flow, and pressure data. (authors). 4 refs., 4 figs
Unbalanced field RF electron gun
Hofler, Alicia
2013-11-12
A design for an RF electron gun having a gun cavity utilizing an unbalanced electric field arrangement. Essentially, the electric field in the first (partial) cell has higher field strength than the electric field in the second (full) cell of the electron gun. The accompanying method discloses the use of the unbalanced field arrangement in the operation of an RF electron gun in order to accelerate an electron beam.
Designing of RF ion source and the power sources system
International Nuclear Information System (INIS)
Rusdiyanto.
1978-01-01
An RF ion source prototype is being developed for the particle accelerator at the Gama Research Centre. Supply of the gas is fed into the plasma chamber by means of neadle valve system. Magnetic field strength of about 500 gauss is applied to the system to improve the ionization efficiency. Components and spare parts of the RF ion source are made based on locally available materials and are discussed in this report. (author)
Low-level RF control system issues for an ADTT accelerator
International Nuclear Information System (INIS)
Ziomek, C.D.; Regan, A.H.; Lynch, M.T.; Bowling, P.S.
1994-01-01
The RF control system for a charged-particle accelerator must maintain the correct amplitude and phase of RF field inside the accelerator cavity in the presence of perturbations, noises, and time varying system components. For an accelerator with heavy beam-loading, fluctuations in the beam current cause large perturbations to the RF field amplitude and phase that must be corrected by the RF control system. The ADTT applications require a high-current, heavily beam-loaded, continuous-wave (CW) accelerator. Additional concerns created by the CW operation include system start-up, beam interruption, and fault recovery. Also, the RF control system for an ADTT facility must include sophisticated automation to reduce the operator interaction and support. This paper describes an RF control system design that addresses these various issues by evaluation a combination of feedback and feed forward control techniques. Experience from the high-current Ground Test Accelerator (GTA) is drawn upon for this RF control system design. Comprehensive computer modeling with the Matrix x software has been used to predict the performance of this RF control system
Energy Technology Data Exchange (ETDEWEB)
Pritzkau, David P.
2002-01-03
RF pulsed heating is a process by which a metal is heated from magnetic fields on its surface due to high-power pulsed RF. When the thermal stresses induced are larger than the elastic limit, microcracks and surface roughening will occur due to cyclic fatigue. Pulsed heating limits the maximum magnetic field on the surface and through it the maximum achievable accelerating gradient in a normal conducting accelerator structure. An experiment using circularly cylindrical cavities operating in the TE{sub 011} mode at a resonant frequency of 11.424 GHz is designed to study pulsed heating on OFE copper, a material commonly used in normal conducting accelerator structures. The high-power pulsed RF is supplied by an X-band klystron capable of outputting 50 MW, 1.5 {micro}s pulses. The test pieces of the cavity are designed to be removable to allow testing of different materials with different surface preparations. A diagnostic tool is developed to measure the temperature rise in the cavity utilizing the dynamic Q change of the resonant mode due to heating. The diagnostic consists of simultaneously exciting a TE{sub 012} mode to steady-state in the cavity at 18 GHz and measuring the change in reflected power as the cavity is heated from high-power pulsed RF. Two experimental runs were completed. One run was executed at a calculated temperature rise of 120 K for 56 x 10{sup 6} pulses. The second run was executed at a calculated temperature rise of 82 K for 86 x 10{sup 6} pulses. Scanning electron microscope pictures show extensive damage occurring in the region of maximum temperature rise on the surface of the test pieces.
High efficiency and broad bandwidth grating coupler between nanophotonic waveguide and fibre
International Nuclear Information System (INIS)
Yu, Zhu; Xue-Jun, Xu; Zhi-Yong, Li; Liang, Zhou; Yu-De, Yu; Jin-Zhong, Yu; Wei-Hua, Han; Zhong-Chao, Fan
2010-01-01
A high efficiency and broad bandwidth grating coupler between a silicon-on-insulator (SOI) nanophotonic waveguide and fibre is designed and fabricated. Coupling efficiencies of 46% and 25% at a wavelength of 1.55 μm are achieved by simulation and experiment, respectively. An optical 3 dB bandwidth of 45 nm from 1530 nm to 1575 nm is also obtained in experiment. Numerical calculation shows that a tolerance to fabrication error of 10 nm in etch depth is achievable. The measurement results indicate that the alignment error of ±2 μm results in less than 1 dB additional coupling loss. (classical areas of phenomenology)
USING THE SCRAP TIRES TO PRODUCE A FLEXIBLE COUPLER
Directory of Open Access Journals (Sweden)
Tahsean A. Hussain
2018-01-01
Full Text Available The scrap tires considered a problematic source of waste, the old rubber tires causes a big environmental problem that is need much money and effort to disposes it safely. In Iraq there are more than two million used tires disposed to the environment annually. one of the tire’s recycling methods is the use of tire layers to produce a new rubber parts used in the engineering and industrial purposes as the bridges and machines dampers, this trend of recycling doesn’t take a sufficient care comparing with the other uses. There are a lot of studies conducted in these field, these studies suggests many methods to manage the huge number of scrap tires, the current paper aims to use the old rubber tires in engineering purposes (especially as a coupler joins the motor or engines with the other equipment as electric dynamo or pumps, the study focusing on the mechanical properties of a strip from a used tires and comparing with one prepared in the lab., and suggesting a new method to use as an engineering parts (for example the coupler lays between the IC engine and the dynamo of an electric generator. One of the results obtained from the experiments, there is no significant difference between the mechanical properties of the old and the new strip, (in the tensile test, the breaking force of the -Lab. tensile specimen- is 137 N whereas the specimen of old tire have a breaking force 113.27 N, but they are same in the elongation. A computational example is suggested to estimate the dimensions of a flexible coupler use an old tire pieces.
Energy Technology Data Exchange (ETDEWEB)
Guo, Jiquan [Stanford Univ., CA (United States)
2008-12-01
In the past decades, there has been increasing interest in pulsed high power RF sources for building high-gradient high-energy particle accelerators. Passive RF pulse compression systems have been used in many applications to match the available RF sources to the loads requiring higher RF power but a shorter pulse. Theoretically, an active RF pulse compression system has the advantage of higher efficiency and compactness over the passive system. However, the key component for such a system an element capable of switching hundreds of megawatts of RF power in a short time compared to the compressed pulse width is still an open problem. In this dissertation, we present a switch module composed of an active window based on the bulk effects in semiconductor, a circular waveguide three-port network and a movable short plane, with the capability to adjust the S-parameters before and after switching. The RF properties of the switch module were analyzed. We give the scaling laws of the multiple-element switch systems, which allow the expansion of the system to a higher power level. We present a novel overmoded design for the circular waveguide three-port network and the associated circular-to-rectangular mode-converter. We also detail the design and synthesis process of this novel mode-converter. We demonstrate an electrically controlled ultra-fast high power X-band RF active window built with PIN diodes on high resistivity silicon. The window is capable of handling multi-megawatt RF power and can switch in 2-300ns with a 1000A current driver. A low power active pulse compression experiment was carried out with the switch module and a 375ns resonant delay line, obtaining 8 times compression gain with a compression ratio of 20.
Straightforward and accurate technique for post-coupler stabilization in drift tube linac structures
Khalvati, Mohammad Reza
2016-01-01
The axial electric field of Alvarez drift tube linacs (DTLs) is known to be susceptible to variations due to static and dynamic effects like manufacturing tolerances and beam loading. Post-couplers are used to stabilize the accelerating fields of DTLs against tuning errors. Tilt sensitivity and its slope have been introduced as measures for the stability right from the invention of post-couplers but since then the actual stabilization has mostly been done by tedious iteration. In the present article, the local tilt-sensitivity slope TS 0 n is established as the principal measure for stabilization instead of tilt sensitivity or some visual slope, and its significance is developed on the basis of an equivalent-circuit diagram of the DTL. Experimental and 3D simulation results are used to analyze its behavior and to define a technique for stabilization that allows finding the best post-coupler settings with just four tilt-sensitivity measurements. CERN ’ s Linac4 DTL Tank 2 and Tank 3 have been stabilized succ...
Design Concepts for RF-DC Conversion in Particle Accelerator Systems
Caspers, F; Grudiev, A; Sapotta, H
2010-01-01
In many particle accelerators considerable amounts of RF power reaching the megawatt level are converted into heat in dummy loads. After an overview of RF power in the range 200 MHz to 1 GHz dissipated at CERN we discuss several developments that have come up in the past using vacuum tube technology for RF-DC conversion. Amongst those the developments of the cyclotron wave converter CWC appears most suitable. With the availability of powerful Schottky diodes the solid state converter aspect has to be addressed as well. One of the biggest problems of Schottky diode based structures is the junction capacity. GaAs and GaN Schottky diodes show a significant reduction of this junction capacity as compared to silicon. Small rectenna type converter units which have been already developed for microwave powered helicopters can be used in waveguides or with coaxial power dividers.
Design of a Multi-Bunch BPM for the Next Linear Collider
International Nuclear Information System (INIS)
Young, Andrew
2003-01-01
The Next Linear Collider (NLC) design requires precise control of colliding trains of high-intensity (1.4 x 10 10 particles/bunch) and low-emittance beams. High-resolution multi-bunch beam position monitors (BPMs) are required to ensure uniformity across the bunch trains with bunch spacing of 1.4ns. A high bandwidth (∼350 MHz) multi-bunch BPM has been designed based on a custom-made stripline sum and difference hybrid on a Teflon-based material. High bandwidth RF couplers were included to allow injection of a calibration tone. Three prototype BPMs were fabricated at SLAC and tested in the Accelerator Test Facility at KEK and in the PEP-II ring at SLAC. Tone calibration data and single-bunch and multi-bunch beam data were taken with high-speed (5Gsa/s) digitizers. Offline analysis determined the deconvolution of individual bunches in the multi-bunch mode by using the measured single bunch response. The results of these measurements are presented in this paper
International Nuclear Information System (INIS)
Herbst, Christian; Herbst, Jirada; Kirschstein, Anika; Leppert, Joerg; Ohlenschlaeger, Oliver; Goerlach, Matthias; Ramachandran, Ramadurai
2009-01-01
The CN n ν class of RF pulse schemes, commonly employed for recoupling and decoupling of nuclear spin interactions in magic angle spinning solid state NMR studies of biological systems, involves the application of a basic 'C' element corresponding to an RF cycle with unity propagator. In this study, the design of CN n ν symmetry-based RF pulse sequences for achieving 13 C- 13 C double-quantum dipolar recoupling and through bond scalar coupling mediated 13 C- 13 C chemical shift correlation has been examined at high MAS frequencies employing broadband, constant-amplitude, phase-modulated basic 'C' elements. The basic elements were implemented as a sandwich of a small number of short pulses of equal duration with each pulse characterised by an RF phase value. The phase-modulation profile of the 'C' element was optimised numerically so as to generate efficient RF pulse sequences. The performances of the sequences were evaluated via numerical simulations and experimental measurements and are presented here
International Nuclear Information System (INIS)
Rasmussen, D.A.; Freeman, R.L.
2001-01-01
The purpose of this Cooperative Research and Development Agreement (CRADA) between UT-Battelle, LLC, (Contractor), and Archimedes Technology Group, (Participant) is to evaluate the design of an RF antenna for a large-bore, high power, steady state plasma processing chamber for material separation. Criteria for optimization will be to maximize the power deposition in the plasma while operating at acceptable voltages and currents in the antenna structure. The project objectives are to evaluate the design of an RF antenna for a large-bore, high power, steady state plasma processing chamber for material separation. Criteria for optimization will be to maximize the power deposition in the plasma while operating at acceptable voltages and currents in the antenna structure
Low Level RF System for Jefferson Lab Cryomodule Test Facility
International Nuclear Information System (INIS)
Tomasz Plawski; Trent Allison; Jean Delayen; J. Hovater; Thomas Powers
2003-01-01
The Jefferson Lab Cryomodule Test Facility (CMTF) has been upgraded to test and commission SNS and CEBAF Energy Upgrade cryomodules. Part of the upgrade was to modernize the superconducting cavity instrumentation and control. We have designed a VXI based RF control system exclusively for the production testing of superconducting cavities. The RF system can be configured to work either in Phase Locked Loop (PLL) or Self Excited Loop (SEL) mode. It can be used to drive either SNS 805 MHz or CEBAF Energy Upgrade 1497 MHz superconducting cavities and can be operated in pulsed or continuous wave (CW) mode. The base design consists of RF-analog and digital sections. The RF-analog section includes a Voltage Control Oscillator (VCO), phase detector, IandQ modulator and ''low phase shift'' limiter. The digital section controls the analog section and includes ADC, FPGA, and DAC . We will discuss the design of the RF system and how it relates to the support of cavity testing
Sirenko, Kostyantyn
2011-01-01
The paper discusses the radiation of compressed high power short RF pulses using two different types of antennas: (i) A simple monopole antenna and (ii) a novel array design, where each of the elements is constructed by combining a compressor and a radiator. The studies on the monopole antenna demonstrate the possibility of a high power short RF pulse\\'s efficient radiation even using simple antennas. The studies on the novel array design demonstrate that a reduced size array with lower pulse distortion and power decay can be constructed by assembling the array from elements each of which integrates a compressor and a radiator. This design idea can be used with any type of antenna array; in this work it is applied to a phased array.
Directory of Open Access Journals (Sweden)
Amna Riaz
2018-01-01
Full Text Available Microelectromechanical Systems (MEMS are devices made up of several electrical and mechanical components. They consist of mechanical functions (sensing, thermal, inertial and electrical functions (switching, decision making on a single chip made by microfabrication methods. These chips exhibit combined properties of the two functions. The size of system has characteristic dimensions less than 1mm but more than 1μm. The configuration of these components determine the final deliverables of the switch. MEMS can be designed to meet user requirements on any level from microbiological application such as biomedical transducers or tissue engineering, to mechanical systems such as microfluidic diagnoses or chemical fuel cells. The low cost, small mass and minimal power consumption of the MEMS makes it possible to readily integrate to any kind of system in any environment. MEMS are faster, better and cheaper. They offer excellent electrical performances. MEMS working at Radio frequencies are RF MEMS. RF-MEMS switches find huge market in the modern telecommunication networks, biological, automobiles, satellites and defense systems because of their lower power consumptions at relatively higher frequencies and better electrical performances. But the reliability is the major hurdle in the fate of RF MEMS switches. Reliability mainly arises due to the presence of residual stresses, charging current, fatigue and creep and contact degradation. The presence of residual stresses in switches the S-Parameters of the switches are affected badly and the residual stress affects the final planarity of the fabricated structure. Design and simulation of an RF-MEMS switch is proposed considering the residual stresses in both on and off state. The operating frequency band is being optimized and the best possible feasible fabrication technique for the proposed switch design is being analyzed. S-Parameters are calculated and a comparison for the switches with stress and
Energy Technology Data Exchange (ETDEWEB)
Chung, K. H.; Lee, K. O.; Shin, H. M.; Chung, I. Y. [KAPRA, Seoul (Korea); Kim, D. I. [Inha University, Incheon (Korea); Noh, S. J. [Dankook University, Seoul (Korea); Ko, S. K. [Ulsan University, Ulsan (Korea); Lee, H. J. [Cheju National University, Cheju (Korea); Choi, W. H. [Korea Advanced Institute of Science and Technology, Taejeon (Korea)
2002-05-01
This study was performed with objective to design and develop the KOMAC proton accelerator RF system. For the development of the high power RF source for CCDTL(coupled cavity drift tube linac), the medium power RF system using the UHF klystron for broadcasting was integrated and with this RF system we obtained the basic design data, operation experience and code-validity test data. Based on the medium power RF system experimental data, the high power RF system for CCDTL was designed and its performed was analyzed. 16 refs., 64 figs., 27 tabs. (Author)
RF Control System Upgrade at CAMD
Suller, Victor P; Jines, Paul; Launey, Daren
2005-01-01
A description is given of the new control system for the RF system of the CAMD light source. The new design being implemented brings all RF signals into the data acquisition system via a modular, custom made, RF detector and renders the amplitude and tune control loops in the VME computer. On line calculations ensure monitoring of proper operation and display the information to the user in an efficient way. In addition, an advanced load impedance monitoring diagnostic has been implemented, being displayed as a Smith Chart, which is based on the system used at the SRS in Daresbury, England.
RF Electron Gun with Driven Plasma Cathode
Khodak, Igor
2005-01-01
It's known that RF guns with plasma cathodes based on solid-state dielectrics are able to generate an intense electron beam. In this paper we describe results of experimental investigation of the single cavity S-band RF gun with driven plasma cathode. The experimental sample of the cathode based on ferroelectric ceramics has been designed. Special design of the cathode permits to separate spatially processes of plasma development and electron acceleration. It has been obtained at RF gun output electron beam with particle energy ~500 keV, pulse current of 4 A and pulse duration of 80 ns. Results of experimental study of beam parameters are referred in. The gun is purposed to be applied as the intense electron beam source for electron linacs.
Rf beam control for the AGS Booster
International Nuclear Information System (INIS)
Brennan, J.M.
1994-01-01
RF beam control systems for hadron synchrotrons have evolved over the past three decades into an essentially standard design. The key difference between hadron and lepton machines is the absence of radiation damping and existence of significant frequency variation in the case of hadrons. Although the motion of the hadron in the potential well of the rf wave is inherently stable it is not strongly damped. Damping must be provided by electronic feedback through the accelerating system. This feedback is typically called the phase loop. The technology of the rf beam control system for the AGS Booster synchrotron is described. First, the overall philosophy of the design is explained in terms of a conventional servo system that regulates the beam horizontal position in the vacuum chamber. The concept of beam transfer functions is fundamental to the mathematics of the design process and is reviewed. The beam transfer functions required for this design are derived from first principles. An overview of the beam signal pick-ups and high level rf equipment is given. The major subsystems, the frequency program, the heterodyne system, and beam feedback loops, are described in detail. Beyond accelerating the beam, the rf system must also synchronize the bunches in the Booster to the buckets in the AGS before transfer. The technical challenge in this process is heightened by the need to accomplish synchronization while the frequency is still changing. Details of the synchronization system are given. This report is intended to serve two purposes. One is to document the hardware and performance of the systems that have been built. The other is to serve as a tutorial vehicle from which the non-expert can not only learn the details of this system but also learn the principles of beam control that have led to the particular design choices made
Rf beam control for the AGS Booster
Energy Technology Data Exchange (ETDEWEB)
Brennan, J.M.
1994-09-26
RF beam control systems for hadron synchrotrons have evolved over the past three decades into an essentially standard design. The key difference between hadron and lepton machines is the absence of radiation damping and existence of significant frequency variation in the case of hadrons. Although the motion of the hadron in the potential well of the rf wave is inherently stable it is not strongly damped. Damping must be provided by electronic feedback through the accelerating system. This feedback is typically called the phase loop. The technology of the rf beam control system for the AGS Booster synchrotron is described. First, the overall philosophy of the design is explained in terms of a conventional servo system that regulates the beam horizontal position in the vacuum chamber. The concept of beam transfer functions is fundamental to the mathematics of the design process and is reviewed. The beam transfer functions required for this design are derived from first principles. An overview of the beam signal pick-ups and high level rf equipment is given. The major subsystems, the frequency program, the heterodyne system, and beam feedback loops, are described in detail. Beyond accelerating the beam, the rf system must also synchronize the bunches in the Booster to the buckets in the AGS before transfer. The technical challenge in this process is heightened by the need to accomplish synchronization while the frequency is still changing. Details of the synchronization system are given. This report is intended to serve two purposes. One is to document the hardware and performance of the systems that have been built. The other is to serve as a tutorial vehicle from which the non-expert can not only learn the details of this system but also learn the principles of beam control that have led to the particular design choices made.
All silicon waveguide spherical microcavity coupler device.
Xifré-Pérez, E; Domenech, J D; Fenollosa, R; Muñoz, P; Capmany, J; Meseguer, F
2011-02-14
A coupler based on silicon spherical microcavities coupled to silicon waveguides for telecom wavelengths is presented. The light scattered by the microcavity is detected and analyzed as a function of the wavelength. The transmittance signal through the waveguide is strongly attenuated (up to 25 dB) at wavelengths corresponding to the Mie resonances of the microcavity. The coupling between the microcavity and the waveguide is experimentally demonstrated and theoretically modeled with the help of FDTD calculations.
Conceptual design of the RF accelerating cavities for a superconducting cyclotron
International Nuclear Information System (INIS)
Maggiore, M.; Calabretta, L.; Di Giacomo, M.; Rifuggiato, D.; Battaglia, D.; Piazza, L.
2006-01-01
A superconducting cyclotron accelerating ions up to 250 A MeV, for medical applications and radioactive ions production is being studied at Laboratori Nazionali del Sud in Catania. The radio frequency (RF) system, working in the fourth harmonic, is based on four normal conducting radio frequency cavities operating at 93 MHz. This paper describes an unusual multi-stem cavity design, performed with 3D electromagnetic codes. Our aim is to obtain a cavity, completely housed inside the cyclotron, with a voltage distribution ranging from 65 kV in the injection region to a peak value of 120 kV in the extraction region, and having a low power consumption
International Nuclear Information System (INIS)
Sarkar, S.; Mondal, J.; Mittal, K.C.
2013-01-01
A single cell 1050 MHz β = 1 elliptical cavity has been designed for possible use in High energy electron accelerator. A prototype Aluminium cavity has been fabricated by die punch method and low power testing of the cavity has been carried out by using VNA. The fundamental mode frequency of the prototype cavity is found out to be 1051.38 MHz and Q (loaded) and Q0 values corresponding to 2 modes are 8439 and 10013 respectively. Cell to cell coupling coefficient is 1.82 % from measurement which matches with the designed value (1.84%). The higher order mode frequencies are also measured and electric field of the cavity is confirmed by bead pull method. Low power RF measurements on the prototype cavity indicate that the critical RF parameters (Qo, f, Kc etc) for the cavity are consistent with the designed value. (author)
RF pulse compression in the NLC test accelerator at SLAC
International Nuclear Information System (INIS)
Lavine, T.L.
1995-01-01
At the Stanford Linear Accelerator Center (SLAC), the authors are designing a Next Linear Collider (NLC) with linacs powered by X-band klystrons with rf pulse compression. The design of the linac rf system is based on X-band prototypes which have been tested at high power, and on a systems-integration test - the Next Linear Collider Test Accelerator (NLCTA) - which is currently under construction at SLAC. This paper discusses some of the systems implications of rf pulse compression, and the use of pulse compression in the NLCTA, both for peak power multiplication and for controlling, by rf phase modulation, intra-pulse variations in the linac beam energy
Design and development of power supplies for high power IOT based RF amplifier
International Nuclear Information System (INIS)
Kumar, Yashwant; Kumari, S.; Ghosh, M.K.; Bera, A.; Sadhukhan, A.; Pal, S.S.; Khare, V.K.; Tiwari, T.P.; Thakur, S.K.; Saha, S.
2013-01-01
Design, development, circuit topology, function of system components and key system specifications of different power supplies for biasing electrodes of Thales Inductive Output Tube (IOT) based high power RF amplifier are presented in this paper. A high voltage power supply (-30 kV, 3.2A dc) with fast (∼microsecond) crowbar protection circuit is designed, developed and commissioned at VECC for testing the complete setup. Other power supplies for biasing grid electrode (300V, 0.5A dc) and Ion Pump (3 kV, 0.1mA dc) of IOT are also designed, developed and tested with actual load. A HV Deck (60kV Isolation) is specially designed in house to place these power supplies which are floating at 30 kV. All these power supplies are powered by an Isolation Transformer (5 kVA, 60 kV isolation) designed and developed in VECC. (author)
Tajaldini, Mehdi; Jafri, Mohd Zubir Mat
2015-04-01
The theory of Nonlinear Modal Propagation Analysis Method (NMPA) have shown significant features of nonlinear multimode interference (MMI) coupler with compact dimension and when launched near the threshold of nonlinearity. Moreover, NMPA have the potential to allow studying the nonlinear MMI based the modal interference to explorer the phenomenon that what happen due to the natural of multimode region. Proposal of all-optical switch based NMPA has approved its capability to achieving the all-optical gates. All-optical gates have attracted increasing attention due to their practical utility in all-optical signal processing networks and systems. Nonlinear multimode interference devices could apply as universal all-optical gates due to significant features that NMPA introduce them. In this Paper, we present a novel Ultra-compact MMI coupler based on NMPA method in low intensity compared to last reports either as a novel design method and potential application for optical NAND, NOR as universal gates on single structure for Boolean logic signal processing devices and optimize their application via studding the contrast ratio between ON and OFF as a function of output width. We have applied NMPA for several applications so that the miniaturization in low nonlinear intensities is their main purpose.
Normal Conducting RF Cavity for MICE
International Nuclear Information System (INIS)
Li, D.; DeMello, A.; Virostek, S.; Zisman, M.; Summers, D.
2010-01-01
Normal conducting RF cavities must be used for the cooling section of the international Muon Ionization Cooling Experiment (MICE), currently under construction at Rutherford Appleton Laboratory (RAL) in the UK. Eight 201-MHz cavities are needed for the MICE cooling section; fabrication of the first five cavities is complete. We report the cavity fabrication status including cavity design, fabrication techniques and preliminary low power RF measurements.
Superconducting RF activities at Cornell University
International Nuclear Information System (INIS)
Kirchgessner, J.; Moffat, D.; Padamsee, H.; Rubin, D.; Sears, J.; Shu, Q.S.
1990-01-01
This paper outlines the RF superconductivity research and development work that has taken place at Cornell Laboratory of Nuclear Studies over the past years. The work that has been performed since the last RF superconductivity workshop is emphasized together with a discussion of the direction of future efforts. Past work is summarized first, focusing on research and development activities in the area of RF superconductivity. Superconducting TeV linear collider is then discussed focusing on the application of superconducting RF to a future TeV linear collider. Linear collider structure development is then described centering on the development of a simpler (thereby cheaper) structure for a TeV linear collider. B-factory with superconducting RF is outlined focusing on the formulation of a conceptual design for a B-factory. B-factory structure development is discussed in relation to the advancement in the capability of SC cavities to carry beam currents of several amperes necessary for a high luminosity storage ring. High gradients are discussed as the key to the realization of a high energy superconducting linac or a superconducting RF B-factory. (N.K.)
Rf control system for a rocket-borne accelerator
International Nuclear Information System (INIS)
Lynch, M.T.; Sorum, L.N.; Keffeler, D.R.
1987-01-01
The Beam Experiments Aboard Rockets (BEAR) accelerator experiment imposes several nonstandard requirements on the rf control system. The experiment is entirely hands-off and must operate under local computer control. The rf control system must be extremely reliable, which implies excellence in design and fabrication as well as redundancy whenever possible. This paper describes the design of the frequency-source, frequency-control, and amplitude-control systems for the BEAR experiment
Comparability of scores on the MMPI-2-RF scales generated with the MMPI-2 and MMPI-2-RF booklets.
Van der Heijden, P T; Egger, J I M; Derksen, J J L
2010-05-01
In most validity studies on the recently released 338-item MMPI-2 (Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989) Restructured Form (MMPI-2-RF; Ben-Porath & Tellegen, 2008; Tellegen & Ben-Porath, 2008), scale scores were derived from the 567-item MMPI-2 booklet. In this study, we evaluated the comparability of the MMPI-2-RF scale scores derived from the original 567-item MMPI-2 booklet with MMPI-2-RF scale scores derived from the 338-item MMPI-2-RF booklet in a Dutch student sample (N = 107). We used a counterbalanced (ABBA) design. We compared results with those previously reported by Tellegen and Ben-Porath (2008). Our findings support the comparability of the scores of the 338-item version and the 567-item version of the 50 MMPI-2-RF scales. We discuss clinical implications and directions for further research.
Design of a Novel W-Sinker RF LDMOS
Directory of Open Access Journals (Sweden)
Xiangming Xu
2015-01-01
Full Text Available A novel RF LDMOS device structure and corresponding manufacturing process are presented in this paper. Deep trench W-sinker (tungsten sinker is employed in this technology to replace the traditional heavily doped diffusion sinker which can shrink chip size of the LDMOS transistor by more than 30% and improve power density. Furthermore, the W-sinker structure reduces the parasitic resistance and inductance and improves thermal conductivity of the device as well. Combined with the adoption of the techniques, like grounded shield, step gate oxide, LDD optimization, and so forth, an advanced technology for RF LDMOS based on conventional 0.35 μm CMOS technology is well established. An F+A power amplifier product with frequency range of 1.8–2.1 GHz is developed for the application of 4G LTE base station and industry leading performance is achieved. The qualification results show that the device reliability and ruggedness can also meet requirement of the application.
A 12 GHz RF Power Source for the CLIC Study
Energy Technology Data Exchange (ETDEWEB)
Schirm, Karl; /CERN; Curt, Stephane; /CERN; Dobert, Steffen; /CERN; McMonagle, Gerard; /CERN; Rossat, Ghislain; /CERN; Syratchev, Igor; /CERN; Timeo, Luca; /CERN; Haase, Andrew /SLAC; Jensen, Aaron; /SLAC; Jongewaard, Erik; /SLAC; Nantista, Christopher; /SLAC; Sprehn, Daryl; /SLAC; Vlieks, Arnold; /SLAC; Hamdi, Abdallah; /Saclay; Peauger, Franck; /Saclay; Kuzikov, Sergey; /Nizhnii Novgorod, IAP; Vikharev, Alexandr; /Nizhnii Novgorod, IAP
2012-07-03
The CLIC RF frequency has been changed in 2008 from the initial 30 GHz to the European X-band 11.9942 GHz permitting beam independent power production using klystrons for CLIC accelerating structure testing. A design and fabrication contract for five klystrons at that frequency has been signed by different parties with SLAC. France (IRFU, CEA Saclay) is contributing a solid state modulator purchased in industry and specific 12 GHz RF network components to the CLIC study. RF pulses over 120 MW peak at 230 ns length will be obtained by using a novel SLED-I type pulse compression scheme designed and fabricated by IAP, Nizhny Novgorod, Russia. The X-band power test stand is being installed in the CLIC Test Facility CTF3 for independent structure and component testing in a bunker, but allowing, in a later stage, for powering RF components in the CTF3 beam lines. The design of the facility, results from commissioning of the RF power source and the expected performance of the Test Facility are reported.
A 12 GHZ RF Power source for the CLIC study
Peauger, F; Curt, S; Doebert, S; McMonagle, G; Rossat, G; Schirm, KM; Syratchev, I; Timeo, L; Kuzikhov, S; Vikharev, AA; Haase, A; Sprehn, D; Jensen, A; Jongewaard, EN; Nantista, CD; Vlieks, A
2010-01-01
The CLIC RF frequency has been changed in 2008 from the initial 30 GHz to the European X-band 11.9942 GHz permitting beam independent power production using klystrons for CLIC accelerating structure testing. A design and fabrication contract for five klystrons at that frequency has been signed by different parties with SLAC. France (IRFU, CEA Saclay) is contributing a solid state modulator purchased in industry and specific 12 GHz RF network components to the CLIC study. RF pulses over 120 MW peak at 230 ns length will be obtained by using a novel SLED-I type pulse compression scheme designed and fabricated by IAP, Nizhny Novgorod, Russia. The X-band power test stand is being installed in the CLIC Test Facility CTF3 for independent structure and component testing in a bunker, but allowing, in a later stage, for powering RF components in the CTF3 beam lines. The design of the facility, results from commissioning of the RF power source and the expected performance of the Test Facility are reported.
Embedded control system for high power RF amplifiers
International Nuclear Information System (INIS)
Sharma, Deepak Kumar; Gupta, Alok Kumar; Jain, Akhilesh; Hannurkar, P.R.
2011-01-01
RF power devices are usually very sensitive to overheat and reflected RF power; hence a protective interlock system is required to be embedded with high power solid state RF amplifiers. The solid state RF amplifiers have salient features of graceful degradation and very low mean time to repair (MTTR). In order to exploit these features in favour of lowest system downtime, a real-time control system is embedded with high power RF amplifiers. The control system is developed with the features of monitoring, measurement and network publishing of various parameters, historical data logging, alarm generation, displaying data to the operator and tripping the system in case of any interlock failure. This paper discusses the design philosophy, features, functions and implementation details of the embedded control system. (author)
Multiband RF circuits and techniques for wireless transmitters
Chen, Wenhua; Ghannouchi, Fadhel M
2016-01-01
This book introduces systematic design methods for passive and active RF circuits and techniques, including state-of-the-art digital enhancement techniques. As the very first book dedicated to multiband RF circuits and techniques, this work provides an overview of the evolution of transmitter architecture and discusses current digital predistortion techniques. Readers will find a collection of novel research ideas and new architectures in concurrent multiband power dividers, power amplifiers and related digital enhancement techniques. This book will be of great interest to academic researchers, R&D engineers, wireless transmitter and protocol designers, as well as graduate students who wish to learn the core architectures, principles and methods of multiband RF circuits and techniques. .
RF pulse compression in the NLC test accelerator at SLAC
International Nuclear Information System (INIS)
Lavine, T.L.
1995-01-01
At the Stanford Linear Accelerator Center (SLAC), we are designing a Next Linear Collider (NLC) with linacs powered by X-band klystrons with rf pulse compression. The design of the linac rf system is based on X-band prototypes which have been tested at high power, and on a systems-integration test---the Next Linear Collider Test Accelerator (NLCTA)---which is currently under construction at SLAC. This paper discusses some of the systems implications of rf pulse compression, and the use of pulse compression in the NLCTA, both for peak power multiplication and for controlling, by rf phase modulation, intra-pulse variations in the linac beam energy. copyright 1995 American Institute of Physics
RF power sources for 5--15 TeV linear colliders
International Nuclear Information System (INIS)
Wilson, P.B.
1996-09-01
After outlining the design of the NLC rf system at 1 TeV, the possibility of a leap in linear collider energy into the 5--15 TeV energy range is considered. To keep the active accelerator length and ac wall-plug power within reasonable bounds, higher accelerating gradients at higher rf frequencies will be necessary. Scaling relations are developed for basic rf system parameters as a function of frequency, and some specific parameter examples are given for colliders at 34 Ghz and 91 Ghz. Concepts for rf pulse compression system design and for high power microwave sources at 34 Ghz (for example sheet-beam and multiple-beam klystrons) are briefly discussed
Model coupler for coupling of atmospheric, oceanic, and terrestrial models
International Nuclear Information System (INIS)
Nagai, Haruyasu; Kobayashi, Takuya; Tsuduki, Katsunori; Kim, Keyong-Ok
2007-02-01
A numerical simulation system SPEEDI-MP, which is applicable for various environmental studies, consists of dynamical models and material transport models for the atmospheric, terrestrial, and oceanic environments, meteorological and geographical databases for model inputs, and system utilities for file management, visualization, analysis, etc., using graphical user interfaces (GUIs). As a numerical simulation tool, a model coupling program (model coupler) has been developed. It controls parallel calculations of several models and data exchanges among them to realize the dynamical coupling of the models. It is applicable for any models with three-dimensional structured grid system, which is used by most environmental and hydrodynamic models. A coupled model system for water circulation has been constructed with atmosphere, ocean, wave, hydrology, and land-surface models using the model coupler. Performance tests of the coupled model system for water circulation were also carried out for the flood event at Saudi Arabia in January 2005 and the storm surge case by the hurricane KATRINA in August 2005. (author)
Fundamentals of RF and microwave transistor amplifiers
Bahl, Inder J
2009-01-01
A Comprehensive and Up-to-Date Treatment of RF and Microwave Transistor Amplifiers This book provides state-of-the-art coverage of RF and microwave transistor amplifiers, including low-noise, narrowband, broadband, linear, high-power, high-efficiency, and high-voltage. Topics covered include modeling, analysis, design, packaging, and thermal and fabrication considerations. Through a unique integration of theory and practice, readers will learn to solve amplifier-related design problems ranging from matching networks to biasing and stability. More than 240 problems are included to help read
International Nuclear Information System (INIS)
Liu, Cheng-Yang
2011-01-01
Photonic crystals have many potential applications because of their ability to control lightwave propagation. We report on the fabrication and optical properties of quasi-two-dimensional photonic crystals with triangular lattice of dielectric rods in air. Rod-type photonic crystal structures were fabricated in silicon by electron beam lithography and dry-etching techniques. Wavelength division multiplexing splitters were fabricated from two-dimensional photonic crystal directional waveguide couplers. Transmission spectra were measured and device operation was shown to be in agreement with theoretical calculations. The splitters can be used in visible light region. Such an approach to photonic element systems should enable new applications for designing components in photonic integrated circuits. -- Highlights: → We report the fabrication and optical properties of rod-type photonic crystal. → The splitter was fabricated by electron beam lithography and dry-etching techniques. → The splitter was composed of directional waveguide couplers. → Measured transmission spectra are in agreement with theoretical calculations. → The splitters can be used in visible light region.
RF SYSTEM FOR THE SNS ACCUMULATOR RING
International Nuclear Information System (INIS)
BLASKIEWICZ, M.; BRENNAN, J.M.; BRODOWSKI, J.; DELONG, J.; METH, M.; SMITH, K.; ZALTSMAN, A.
2001-01-01
During accumulation the RF beam current in the spallation neutron source ring rises from 0 to 50 amperes. A clean, 250 nanosecond gap is needed for the extraction kicker risetime. Large momentum spread and small peak current are needed to prevent instabilities and stopband related losses. A robust RF system meeting these requirements has been designed
Development of new S-band RF window for stable high-power operation in linear accelerator RF system
Joo, Youngdo; Lee, Byung-Joon; Kim, Seung-Hwan; Kong, Hyung-Sup; Hwang, Woonha; Roh, Sungjoo; Ryu, Jiwan
2017-09-01
For stable high-power operation, a new RF window is developed in the S-band linear accelerator (Linac) RF systems of the Pohang Light Source-II (PLS-II) and the Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL). The new RF window is designed to mitigate the strength of the electric field at the ceramic disk and also at the waveguide-cavity coupling structure of the conventional RF window. By replacing the pill-box type cavity in the conventional RF window with an overmoded cavity, the electric field component perpendicular to the ceramic disk that caused most of the multipacting breakdowns in the ceramic disk was reduced by an order of magnitude. The reduced electric field at the ceramic disk eliminated the Ti-N coating process on the ceramic surface in the fabrication procedure of the new RF window, preventing the incomplete coating from spoiling the RF transmission and lowering the fabrication cost. The overmoded cavity was coupled with input and output waveguides through dual side-wall coupling irises to reduce the electric field strength at the waveguide-cavity coupling structure and the possibility of mode competitions in the overmoded cavity. A prototype of the new RF window was fabricated and fully tested with the Klystron peak input power, pulse duration and pulse repetition rate of 75 MW, 4.5 μs and 10 Hz, respectively, at the high-power test stand. The first mass-produced new RF window installed in the PLS-II Linac is running in normal operation mode. No fault is reported to date. Plans are being made to install the new RF window to all S-band accelerator RF modules of the PLS-II and PAL-XFEL Linacs. This new RF window may be applied to the output windows of S-band power sources like Klystron as wells as the waveguide windows of accelerator facilities which operate in S-band.
Development of L-band pillbox RF window
International Nuclear Information System (INIS)
Takeuchi, Y.; Fukuda, S.; Hisamatsu, H.; Saito, Y.; Takahashi, A.
1994-01-01
A pillbox RF output window was developed for the L-band pulsed klystron for the Japanese Hadron Project (JHP) 1-GeV proton linac. The window was designed to withstand a peak RF power of 6 MW, where the pulse width is 600 μsec and the repetition rate is 50 Hz. A high power model was fabricated using an alumina ceramic which has a low loss tangent of 2.5x10 -5 . A high power test was successfully performed up to a 113 kW RF average power with a 4 MW peak power, a 565 μsec pulse width and a 50 Hz repetition rate. By extrapolating the data of this high power test, the temperature rise of the ceramic is estimated low enough at the full RF power of 6 MW. Thus this RF window is expected to satisfy the specifications of the L-band Klystron. (author)
Keens, Simon; Rossa, Bernhard; Frei, Marcel
2016-03-01
As the semiconductor industry proceeds to develop ever better sources of extreme ultraviolet (EUV) light for photolithography applications, two distinct technologies have come to prominence: Tin-plasma and free electron laser (FEL) sources. Tin plasma sources have been in development within the industry for many years, and have been widely reported. Meanwhile, FELs represent the most promising alternative to create high power EUV frequencies and, while tin-plasma source development has been ongoing, such lasers have been continuously developed by academic institutions for use in fundamental research programmes in conjunction with universities and national scientific institutions. This paper follows developments in the field of academic FELs, and presents information regarding novel technologies, specifically in the area of RF design strategy, that may be incorporated into future industrial FEL systems for EUV lithography in order to minimize the necessary investment and operational costs. It goes on to try to assess the cost-benefit of an alternate RF design strategy, based upon previous studies.
Design and application of multilayer monolithic microwave integrated circuit transformers
Energy Technology Data Exchange (ETDEWEB)
Economides, S.B
1999-07-01
The design and performance of planar spiral transformers, using multilayer GaAs and silicon MMIC technology, are presented. This multilayer technology gives new opportunities for improving the performance of planar transformers, couplers and baluns. Planar transformers have high parasitic resistance and capacitance and low levels of coupling. Using multilayer technology these problems are overcome by applying a multilayer structure of three metal layers separated by two polyimide dielectric layers. The improvements gained by placing the conductors on different metal layers, and using conductors raised on polyimide layers for low capacitance, have been investigated. The circuits were fabricated using a novel experimental fabrication process, which uses entirely standard materials and techniques and is compatible with BJT's and silicon-germanium HBT's. The transformers were all characterised up to 20 GHz using RF-on-wafer measurements. They demonstrated good performance, considering the experimental nature of in-house multilayer technology and the difficulties in simulating these three-dimensional new geometries. With high resistivity substrates, the silicon components achieved virtually the same performance as their gallium arsenide counterparts. The transformers were then used in simulations of transformer-coupled HBT amplifier circuits, to demonstrate their capabilities. It was shown that these circuits present good performance compared to standard off-the shelf component circuits and are very promising for use in most multilayer MMIC applications. The structures were further used in coupling configurations, and applied in balun circuits and pushpull amplifiers. The spiral transformer coupler can operate at low frequencies without using up much chip area. In a balun configuration, the balun can compensate for coupling and phase imbalance and operates over 5 to 15 GHz. The spiral coupler does not always need multilayer processing, so the balun may be
Basic design considerations for free-electron lasers driven by electron beams from RF accelerators
Gover, A.; Freund, H.; Granatstein, V. L.; McAdoo, J. H.; Tang, C.-M.
A design procedure and design criteria are derived for free-electron lasers driven by electron beams from RF accelerators. The procedure and criteria permit an estimate of the oscillation-buildup time and the laser output power of various FEL schemes: with waveguide resonator or open resonator, with initial seed-radiation injection or with spontaneous-emission radiation source, with a linear wiggler or with a helical wiggler. Expressions are derived for computing the various FEL parameters, allowing for the design and optimization of the FEL operational characteristics under ideal conditions or with nonideal design parameters that may be limited by technological or practical constraints. The design procedure enables one to derive engineering curves and scaling laws for the FEL operating parameters. This can be done most conveniently with a computer program based on flowcharts given in the appendices.
International Nuclear Information System (INIS)
Nagai, Ryoji; Hajima, Ryoichi; Nishimori, Nobuyuki; Sawamura, Masaru; Kikuzawa, Nobuhiro; Shizuma, Toshiyuki; Minehara, Eisuke
2001-01-01
An optical resonator with a high-efficient output coupler was developed for the JAERI far-infrared free-electron laser. The optical resonator is symmetrical near-concentric geometry with an insertable scraper output coupler. As a result of the development of the optical resonator, the JAERI-FEL has been successfully, lased with averaged power over 1 kW. Performance of the optical resonator with the output coupler was evaluated at optical wavelength of 22 μm by using an optical mode calculation code. The output coupling and diffractive loss with a dominant eigen-mode of the resonator were calculated using an iterative computation called Fox-Li procedure. An efficiency factor of the optical resonator was introduced for the evaluation of the optical resonator performance. The efficiency factor was derived by the amount of the output coupling and diffractive loss of the optical resonator. It was found that the optical resonator with the insertable scraper coupler was the most suitable to a high-power and high-efficient far-infrared free-electron laser. (author)
Development of a novel rf waveguide vacuum valve
Grudiev, A
2006-01-01
The development of a novel rf waveguide vacuum valve is presented. The rf design is based on the use of TE0n modes of circular waveguides. In the device, the TE01 mode at the input is converted into a mixture of several TE0n modes which provide low-loss rf power transmission across the vacuum valve gap, these modes are then converted back into the TE01 mode at the output. There are a number of advantages associated with the absence of surface fields in the region of the valve: ⢠Possibility to use commercially available vacuum valves equipped with two specially designed mode converter sections. ⢠No necessity for an rf contact between these two sections. ⢠Increased potential for high power rf transmission. This technology can be used for all frequencies for which vacuum waveguides are used. In rectangular waveguides, mode converters from the operating mode into the TE01 mode and back again are necessary. Experimental results for the 30 GHz valves developed for the CLIC Test Facility 3 (CTF3) a...
Feng, Shuo; Ji, Jim
2014-04-01
Parallel excitation (pTx) techniques with multiple transmit channels have been widely used in high field MRI imaging to shorten the RF pulse duration and/or reduce the specific absorption rate (SAR). However, the efficiency of pulse design still needs substantial improvement for practical real-time applications. In this paper, we present a detailed description of a fast pulse design method with Fourier domain gridding and a conjugate gradient method. Simulation results of the proposed method show that the proposed method can design pTx pulses at an efficiency 10 times higher than that of the conventional conjugate-gradient based method, without reducing the accuracy of the desirable excitation patterns.
Development of C-band High-Power Mix-Mode RF Window
Michizono, S; Matsumoto, T; Nakao, K; Takenaka, T
2004-01-01
High power c-band (5712 MHz) rf system (40 MW, 2 μs, 50 Hz) is under consideration for the electron-linac upgrade aimed for the super KEKB project. An rf window, which isolates the vacuum and pass the rf power, is one of the most important components for the rf system. The window consists of a ceramic disk and a pill-box housing. The mix-mode rf window is designed so as to decrease the electric field on the periphery of the ceramic disk. A resonant ring is assembled in order to examine the high-power transmission test. The window was tested up to the transmission power of 160 MW. The rf losses are also measured during the rf operation.
Rf system considerations for a large hadron collider
International Nuclear Information System (INIS)
Raka, E.
1988-01-01
In this paper, we shall discuss how we arrive at a particular choice of voltage and frequency; the type of acceleration structure that would be suitable for obtaining the required voltage and resonant impedance; static beam loading including a simplified beam stability criterion involving the beam current and total rf system shunt impedance; the basic principle of rf phase and frequency control loops; and the effect of rf noise and its interaction with these loops. Finally, we shall consider the need for and design of rf systems to damp independently coherent oscillations of individual bunches or groups of bunches. 30 refs., 17 figs., 2 tabs
Superconducting cavities for HERA
International Nuclear Information System (INIS)
Dwersteg, B.; Ebeling, W.; Moeller, W.D.; Renken, D.; Proch, D.; Sekutowicz, J.; Susta, J.; Tong, D.
1988-01-01
Superconducting 500 MHz cavities are developed to demonstrate the feasibility of upgrading the e-beam energy of the HERA storage ring. A prototype module with 2 x 4 cell resonators and appropriate fundamental and higher mode couplers has been designed at DESY and is being built by industrial firms. The design and results of RF and cryogenic measurements are reported in detail. 17 references, 10 figures, 2 tables
Superconducting rf activities at Cornell University
International Nuclear Information System (INIS)
Padamsee, H.; Hakimi, M.; Kirchgessner, J.
1988-01-01
Development of rf superconductivity for high energy accelerators has been a robust activity at the Cornell Laboratory of Nuclear Studies (LNS) for many years. In order to realize the potential of rf superconductivity, a two-pronged approach has been followed. On the one hand accelerator applications were selected where the existing state-of-the art of superconducting rf is competitive with alternate technologies, then LNS engaged in a program to design, construct and test suitable superconducting cavities, culminating in a full system test in an operating accelerator. On the second front the discovery and invention of ideas, techniques and materials required to make superconducting rf devices approach the ideal in performance has been aggressively pursued. Starting with the development of superconducting cavities for high energy electron synchrotrons, the technology was extended to high energy e + e - storage rings. The LE5 cavity design has now been adopted for use in the Continuous Electron Beam Accelerator Facility (CEBAF). When completed, this project will be one of the largest applications of SRF technology, using 440 LE5 modules[4]. In the last two years, the cavity design and the technology have been transferred to industry and CEBAF. Cornell has tested the early industrial prototypes and cavity pairs. LNS has developed, in collaboration with CEBAF, designs and procedures for cavity pair and cryomodule assembly and testing. Advanced research for future electron accelerators is badly needed if particle physicists hope to expand the energy frontier. Superconducting cavity technology continues to offer attractive opportunities for further advances in achievable voltage at reasonable cost for future accelerators. For Nb, the full potential implies an order of magnitude increase over current capabilities. 20 references, 11 figures
High power rf component testing for the NLC
International Nuclear Information System (INIS)
Vlieks, A.E.; Fowkes, W.R.; Loewen, R.J.; Tantawi, S.G.
1998-09-01
In the Next Linear Collider (NLC), the high power rf components must be capable of handling peak rf power levels in excess of 600 MW. In the current view of the NLC, even the rectangular waveguide components must transmit at least 300 MW rf power. At this power level, peak rf fields can greatly exceed 100 MV/m. The authors present recent results of high power tests performed at the Accelerator Structure Test Area (ASTA) at SLAC. These tests are designed to investigate the rf breakdown limits of several new components potentially useful for the NLC. In particular, the authors tested a new TE 01 --TE 10 circular to rectangular wrap-around mode converter, a modified (internal fin) Magic Tee hybrid, and an upgraded flower petal mode converter
Coupler tuning for constant gradient travelling wave accelerating structures
International Nuclear Information System (INIS)
Guo Xingkun; Ma Yanyun; Wang Xiulong
2013-01-01
The method of the coupler tuning for the constant gradient traveling wave accelerating structure was described and the formula of coupling coefficient p was deduced on the basis of analyzing the existing methods for the constant impedance traveling wave accelerating structures and coupling-cavity chain equivalent circuits. The method and formula were validated by the simulation result by CST and experiment data. (authors)
Bevalac injector final stage RF amplifier upgrades
International Nuclear Information System (INIS)
Howard, D.; Calvert, J.; Dwinell, R.; Lax, J.; Lindner, A.; Richter, R.; Ridgeway, W.
1991-01-01
With the assistance of the DOE In-house Energy Management Program, the Bevalac injector final stage RF amplifier systems have been successfully upgraded to reduce energy consumption and operating costs. This recently completed project removed the energy-inefficient plate voltage modulator circuits that were used in conjunction with the final stage RF amplifiers. Construction, design, and operating parameters are described in detail
RF system modeling and controller design for the European XFEL
International Nuclear Information System (INIS)
Schmidt, Christian
2011-06-01
The European XFEL is being constructed at the Deutsche Elektronen Synchrotron DESY to generate intense, ultrashort pulses of highly coherent and monochromatic X-Rays for material science research. X-ray flashes are generated by accelerating electron bunches within superconducting cavities with radio frequency (RF) fields to energies up to 17.5 GeV. The digital control of these fields requires extremely high quality in order to achieve the physical processes of photon generation. DESY offers with FLASH a pilot test facility, allowing to test and develop most necessary components, even before the XFEL is conducted. Current field control is based on a proportional feedback controller in addition to a constant feedforward drive, which do not meet the high requirements of the XFEL. This thesis shows that a model based controller design can achieve the necessary field regulation requirements. A linear, time invariant ''black box model'' is estimated, which characterizes the essential dynamic behavior. This model is not based on physical assumptions, but describes exclusively the transfer behavior of the plant. The acceleration modules are operated in a pulsed mode, in which the RF field must be kept constant for a finite period. The character of the disturbances and variations from pulse-to-pulse, together with the properties of the system, require a combination of controlled feedforward drive and feedback. Generally unpredictable, low frequency pulse-to-pulse variations are suppressed by the feedback controller. The structural design of the complex multivariable feedback controller is given, which constrains the model based design approach to assign the controller parameters only. Estimation of the parameters, which can not be tuned manually, is done by the method of H loop shaping which is often applied in modern control theory. However, disturbances within a pulse are in a high frequency range concerning the short pulse duration. They are not sufficiently suppressed
Indoor Wireless RF Energy Transfer for Powering Wireless Sensors
Directory of Open Access Journals (Sweden)
H. Visser
2012-12-01
Full Text Available For powering wireless sensors in buildings, rechargeable batteries may be used. These batteries will be recharged remotely by dedicated RF sources. Far-field RF energy transport is known to suffer from path loss and therefore the RF power available on the rectifying antenna or rectenna will be very low. As a consequence, the RF-to-DC conversion efficiency of the rectenna will also be very low. By optimizing not only the subsystems of a rectenna but also taking the propagation channel into account and using the channel information for adapting the transmit antenna radiation pattern, the RF energy transport efficiency will be improved. The rectenna optimization, channel modeling and design of a transmit antenna are discussed.
Directory of Open Access Journals (Sweden)
Antwi Nimo
2015-04-01
Full Text Available In this paper, analytical modeling of passive rectifying circuits and the harvesting of electromagnetic (EM power from intentionally generated as well as from ubiquitous sources are presented. The presented model is based on the linearization of rectifying circuits. The model provides an accurate method of determining the output characteristics of rectifying circuits. The model was verified with Advance Design System (ADS Harmonic balance (HB simulations and measurements. The results from the presented model were in agreement with simulations and measurements. Consequently design considerations and trade-off of radio frequency (RF harvesters are discussed. To verify the exploitation of ambient RF power sources for operation of sensors, a dual-band antenna with a size of ~λ/4 at 900MHz and a passive dual-band rectifier that is able to power a commercial Thermo-Hygrometer requiring ~1.3V and 0.5MΩ from a global system for mobile communications (GSM base station is demonstrated. The RF power delivered by the receiving dual-band antenna at a distance of about 110 m from the GSM base station ranges from -27 dBm to -50 dBm from the various GSM frequency bands. Additionally, wireless range measurements of the RF harvesters in the industrial, scientific and medical (ISM band 868MHz is presented at indoor conditions.
Energy Technology Data Exchange (ETDEWEB)
Lucija, Lukovac
2007-07-01
In order to limit the number of thermal shocks in the spallation targets and in the core of an ADS (Accelerator Driven System), it is necessary to limit the number of failures of the beam accelerating system. This article presents the improvements in terms of reliability for 2 sub-systems of the ADS: the control system that is in charge of the RF power equipment that delivers the energy necessary to the accelerating system and the power coupler whose purpose is to transfer energy from RF generator to the accelerating cavities. The digitalization of the control system has allowed the application of a compensation method: if one of the cavities fails, the neighbouring cavities are regulated to limit the consequences of the failure on the beam. As for the power coupler, the ceramic window has been designed with great care. The improvements will be tested on 2 prototypes that are being built. (A.C.)
Straightforward and accurate technique for post-coupler stabilization in drift tube linac structures
Directory of Open Access Journals (Sweden)
Mohammad Reza Khalvati
2016-04-01
Full Text Available The axial electric field of Alvarez drift tube linacs (DTLs is known to be susceptible to variations due to static and dynamic effects like manufacturing tolerances and beam loading. Post-couplers are used to stabilize the accelerating fields of DTLs against tuning errors. Tilt sensitivity and its slope have been introduced as measures for the stability right from the invention of post-couplers but since then the actual stabilization has mostly been done by tedious iteration. In the present article, the local tilt-sensitivity slope TS_{n}^{′} is established as the principal measure for stabilization instead of tilt sensitivity or some visual slope, and its significance is developed on the basis of an equivalent-circuit diagram of the DTL. Experimental and 3D simulation results are used to analyze its behavior and to define a technique for stabilization that allows finding the best post-coupler settings with just four tilt-sensitivity measurements. CERN’s Linac4 DTL Tank 2 and Tank 3 have been stabilized successfully using this technique. The final tilt-sensitivity error has been reduced from ±100%/MHz down to ±3%/MHz for Tank 2 and down to ±1%/MHz for Tank 3. Finally, an accurate procedure for tuning the structure using slug tuners is discussed.
Straightforward and accurate technique for post-coupler stabilization in drift tube linac structures
Khalvati, Mohammad Reza; Ramberger, Suitbert
2016-04-01
The axial electric field of Alvarez drift tube linacs (DTLs) is known to be susceptible to variations due to static and dynamic effects like manufacturing tolerances and beam loading. Post-couplers are used to stabilize the accelerating fields of DTLs against tuning errors. Tilt sensitivity and its slope have been introduced as measures for the stability right from the invention of post-couplers but since then the actual stabilization has mostly been done by tedious iteration. In the present article, the local tilt-sensitivity slope TSn' is established as the principal measure for stabilization instead of tilt sensitivity or some visual slope, and its significance is developed on the basis of an equivalent-circuit diagram of the DTL. Experimental and 3D simulation results are used to analyze its behavior and to define a technique for stabilization that allows finding the best post-coupler settings with just four tilt-sensitivity measurements. CERN's Linac4 DTL Tank 2 and Tank 3 have been stabilized successfully using this technique. The final tilt-sensitivity error has been reduced from ±100 %/MHz down to ±3 %/MHz for Tank 2 and down to ±1 %/MHz for Tank 3. Finally, an accurate procedure for tuning the structure using slug tuners is discussed.
Design of an RF window for L-band CW klystron based on thermal-stress analysis
International Nuclear Information System (INIS)
Yamaguchi, Seiya; Sato, Isamu; Konashi, Kenji; Ohshika, Junji.
1993-01-01
Design of klystron RF window has been performed based on a thermal-stress analysis for L-band CW electron linac for nuclear wastes transmutation. It was shown that the hoop stress for a modified disk is 46% of that of normal disk. Thermal load test has been done which indicated that the modified disk is proof against power twice as much as that for the normal disk. (author)
Synchronization of RF fields of Indus 2 RF cavities for proper injection and acceleration of beam
International Nuclear Information System (INIS)
Tiwari, Nitesh; Bagduwal, Pritam S.; Lad, M.; Hannurkar, P.R.
2009-01-01
Indus-2 is a synchrotron light source with designed parameters of 2.5 GeV, 300 mA beam current. Four RF cavities fed from four RF power stations have been used for beam acceleration from 550 MeV to 2.5 GeV and synchrotron loss compensation. Particle should reach the RF cavity at the proper phase for proper acceptance of the beam in ring. At injection if the phase is not proper the acceptance efficiency reduces and the maximum stored current in the ring also gets limited. Equal contribution from four cavities at every value of current and energy level is very important. Improper phase will cause the imbalance of the power among different station hence will limit maximum stored current and reduce life time of the stored beam. Phase optimization was done in two-step, first at injection to have better injection rate and the stations were operated at the sufficient power for control loops to operate. Then at 2 GeV and 2.5 GeV energy so that beam extracts equal power from all four RF stations. Phase synchronization of all four cavities from injection to 2.5 GeV has already been done at 50 mA stored beam current. If phases of RF fields inside four RF cavities is not proper then beam will not see the total RF voltage as summation of all four cavity gap voltages, hence it is a very important parameter to be optimized and maintained during operation. (author)
The New RF Control System for the CERN SPS Accelerator
Baudrenghien, P; Linnecar, Trevor Paul R; Marty, H; Molendijk, J C; Pilchen, Y; Wehrle, U; Weierud, F
1996-01-01
The old SPS RF control system designed in 1972 has been replaced completely, i.e. both hardware and software. The new system has to control both RF equipment conceived during the last 23 years and future (modern) equipment. Using information analysis methods, we derived a model of an RF command and designed a data base accordingly (ORACLE®). Information from this data base is used for command generation and processing and also for archiving settings. The advantage is purely generic software, i.e. the same computer code is used for switching on an RF amplifier, as for setting a frequency synthesizer. New equipment is added very simply by entering new records in the data base. Additional features include a reservation scheme whereby a user can take private control of any piece of equipment, a reporting facility notifying the user of the simultaneous control activity by other users on RF equipment, and a capability scheme assigning a level of expertise to each user restricting action on the equipment.
Studies of RF sheaths and diagnostics on IShTAR
Energy Technology Data Exchange (ETDEWEB)
Crombé, K., E-mail: Kristel.Crombe@UGent.be [Department of Applied Physics, Ghent University, Ghent (Belgium); LPP-ERM/KMS, Royal Military Academy, Brussels (Belgium); Devaux, S.; Faudot, E.; Heuraux, S.; Moritz, J. [YIJL, UMR7198 CNRS-Université de Lorraine, Nancy (France); D’Inca, R.; Faugel, H.; Fünfgelder, H.; Jacquot, J.; Ochoukov, R. [Max-Planck-Institut für Plasmaphysik, Garching (Germany); Louche, F.; Tripsky, M.; Van Eester, D.; Wauters, T. [LPP-ERM/KMS, Royal Military Academy, Brussels (Belgium); Noterdaeme, J.-M. [Department of Applied Physics, Ghent University, Ghent (Belgium); Max-Planck-Institut für Plasmaphysik, Garching (Germany)
2015-12-10
IShTAR (Ion cyclotron Sheath Test ARrangement) is a linear magnetised plasma test facility for RF sheaths studies at the Max-Planck-Institut für Plasmaphysik in Garching. In contrast to a tokamak, a test stand provides more liberty to impose the parameters and gives better access for the instrumentation and antennas. The project will support the development of diagnostic methods for characterising RF sheaths and validate and improve theoretical predictions. The cylindrical vacuum vessel has a diameter of 1 m and is 1.1 m long. The plasma is created by an external cylindrical plasma source equipped with a helical antenna that has been designed to excite the m=1 helicon mode. In inductive mode, plasma densities and electron temperatures have been characterised with a planar Langmuir probe as a function of gas pressure and input RF power. A 2D array of RF compensated Langmuir probes and a spectrometer are planned. A single strap RF antenna has been designed; the plasma-facing surface is aligned to the cylindrical plasma to ease the modelling. The probes will allow direct measurements of plasma density profiles in front of the RF antenna, and thus a detailed study of the density modifications induced by RF sheaths, which influences the coupling. The RF antenna frequency has been chosen to study different plasma wave interactions: the accessible plasma density range includes an evanescent and propagative behaviour of slow or fast waves, and allows the study of the effect of the lower hybrid resonance layer.
rf traveling-wave electron gun for photoinjectors
Schaer, Mattia; Citterio, Alessandro; Craievich, Paolo; Reiche, Sven; Stingelin, Lukas; Zennaro, Riccardo
2016-07-01
The design of a photoinjector, in particular that of the electron source, is of central importance for free electron laser (FEL) machines where a high beam brightness is required. In comparison to standard designs, an rf traveling-wave photocathode gun can provide a more rigid beam with a higher brightness and a shorter pulse. This is illustrated by applying a specific optimization procedure to the SwissFEL photoinjector, for which a brightness improvement up to a factor 3 could be achieved together with a double gun output energy compared to the reference setup foreseeing a state-of-the-art S-band rf standing-wave gun. The higher brightness is mainly given by a (at least) double peak current at the exit of the gun which brings benefits for both the beam dynamics in the linac and the efficiency of the FEL process. The gun design foresees an innovative coaxial rf coupling at both ends of the structure which allows a solenoid with integrated bucking coil to be placed around the cathode in order to provide the necessary focusing right after emission.
RF and microwave engineering fundamentals of wireless communications
Gustrau, Frank
2012-01-01
This book provides a fundamental and practical introduction to radio frequency and microwave engineering and physical aspects of wireless communication In this book, the author addresses a wide range of radio-frequency and microwave topics with emphasis on physical aspects including EM and voltage waves, transmission lines, passive circuits, antennas, radio wave propagation. Up-to-date RF design tools like RF circuit simulation, EM simulation and computerized smith charts, are used in various examples to demonstrate how these methods can be applied effectively in RF engineering
A Metamaterial-Inspired Approach to RF Energy Harvesting
Fowler, Clayton; Zhou, Jiangfeng
2016-03-01
We demonstrate an RF energy harvesting rectenna design based on a metamaterial perfect absorber (MPA). With the embedded Schottky diodes, the rectenna converts captured RF energy to DC currents. The Fabry-Perot cavity resonance of the MPA greatly improves the amount of energy captured and hence improves the rectification efficiency. Furthermore, the FP resonance exhibits a high Q-factor and significantly increases the voltage across the Schottky diodes. This leads to a factor of 16 improvement of RF-DC conversion efficiency at ambient intensity level.