Science.gov

Sample records for rf heating survey

  1. RF pulsed heating

    NASA Astrophysics Data System (ADS)

    Pritzkau, David Peace

    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 TE011 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 μs 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 TE012 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 × 106 pulses. The second run was executed at a calculated temperature rise of 82 K for 86 × 106 pulses. Scanning electron microscope pictures show extensive damage occurring in the region of maximum temperature rise on the surface of the test pieces.

  2. RF Pulsed Heating

    NASA Astrophysics Data System (ADS)

    Pritzkau, D. P.

    2002-01-01

    RF pulsed heating is a process by which a metal is heated from magnetic elds 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 eld 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 TE011 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 s perent surface preparations.he cavity are designed to 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 TE012 mode to steady-state in the cavity at 18 GHz and measuring the change in re ected 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 56 106 pulses. The second run was executed at a calculated temperature rise of 82 K for 86106 pulses. Scanning electron microscope pictures show extensive damage occurring in the region of maximum temperature rise on the surface of the test pieces.

  3. RF heating of nanoclusters for cancer therapy

    NASA Astrophysics Data System (ADS)

    Letfullin, Renat R.; Letfullin, Alla R.; George, Thomas F.

    2015-03-01

    Nanodrugs selectively delivered to a tumor site can be activated by radiation for drug release, or nanoparticles (NPs) can be used as a drug themselves by producing biological damage in cancer cells through thermal, mechanical ablations or charged particle emission. Radio-frequency (RF) waves have an excellent ability to penetrate into the human body without causing healthy tissue damage, which provides a great opportunity to activate/heat NPs delivered inside the body as a contrast agent for diagnosis and treatment purposes. However the heating of NPs in the RF range of the spectrum is controversial in the research community because of the low power load of RF waves and low absorption of NPs in the RF range. To resolve these weaknesses in the RF activation of NPs and dramatically increase absorption of contrast agents in tumor, we suggest aggregating the nanoclusters inside or on the surface of the cancer cells. We simulate space distribution of temperature changes inside and outside metal and dielectric nanopraticles/nanoclusters, determine the number of nanoparticles needed to form a cluster, and estimate the thermal damage area produced in surrounding medium by nanopraticles/nanoclusters heated in the RF field.

  4. Inductance of rf-wave-heated plasmas.

    PubMed

    Farshi, E; Todo, Y

    2003-03-14

    The inductance of rf-wave-heated plasmas is derived. This inductance represents the inductance of fast electrons located in a plateau during their acceleration due to electric field or deceleration due to collisions and electric field. This inductance has been calculated for small electric fields from the two-dimensional Fokker-Planck equation as the flux crossing the surface of critical energy mv(2)(ph)/2 in the velocity space. The new expression may be important for radio-frequency current drive ramp-up, current drive efficiency, current profile control, and so on in tokamaks. This inductance may be incorporated into transport codes that study plasma heating by rf waves.

  5. Toroidal Rotation in RF Heated JET Plasmas

    SciTech Connect

    Eriksson, L.-G.; Nave, F.; Zastrow, K.-D.

    2007-09-28

    Experiments have been carried out on JET aimed at studying rotation in RF heated plasmas with low external momentum input. Both plasmas with Ion Cyclotron Resonance Frequency (ICRF) heating and Lower Hybrid Current Drive (LHCD) have been investigated. The rotation profiles are measured by Charge Exchange recombination spectroscopy, using short diagnostic Neutral Beam Injection (NBI) pulses. Moreover, the temporal evolution of the central rotation could in some cases be deduced from MHD activity. While most of the measurements were focussed on ICRF heating, the profiles measured in plasmas with LHCD are interesting since they are the first reported from JET in such plasmas. In particular, they allowed for studies of rotation in RF heated plasmas with q>1. The experimental results are presented together with an analysis of the torque from ICRF heated fast ions.

  6. Experimental Study of RF Pulsed Heating

    SciTech Connect

    Laurent, Lisa; Tantawi, Sami; Dolgashev, Valery; Nantista, Christopher; Higashi, Yasuo; Aicheler, Markus; Heikkinen, Samuli; Wuensch, Walter; /CERN

    2011-11-04

    Cyclic thermal stresses produced by rf pulsed heating can be the limiting factor on the attainable reliable gradients for room temperature linear accelerators. This is especially true for structures that have complicated features for wakefield damping. These limits could be pushed higher by using special types of copper, copper alloys, or other conducting metals in constructing partial or complete accelerator structures. Here we present an experimental study aimed at determining the potential of these materials for tolerating cyclic thermal fatigue due to rf magnetic fields. A special cavity that has no electric field on the surface was employed in these studies. The cavity shape concentrates the magnetic field on one flat surface where the test material is placed. The materials tested in this study have included oxygen free electronic grade copper, copper zirconium, copper chromium, hot isostatically pressed copper, single crystal copper, electroplated copper, Glidcop(reg. sign), copper silver, and silver plated copper. The samples were exposed to different machining and heat treatment processes prior to rf processing. Each sample was tested to a peak pulsed heating temperature of approximately 110 C and remained at this temperature for approximately 10 x 10{sup 6} rf pulses. In general, the results showed the possibility of pushing the gradient limits due to pulsed heating fatigue by the use of copper zirconium and copper chromium alloys.

  7. Experimental study of rf pulsed heating

    NASA Astrophysics Data System (ADS)

    Laurent, Lisa; Tantawi, Sami; Dolgashev, Valery; Nantista, Christopher; Higashi, Yasuo; Aicheler, Markus; Heikkinen, Samuli; Wuensch, Walter

    2011-04-01

    Cyclic thermal stresses produced by rf pulsed heating can be the limiting factor on the attainable reliable gradients for room temperature linear accelerators. This is especially true for structures that have complicated features for wakefield damping. These limits could be pushed higher by using special types of copper, copper alloys, or other conducting metals in constructing partial or complete accelerator structures. Here we present an experimental study aimed at determining the potential of these materials for tolerating cyclic thermal fatigue due to rf magnetic fields. A special cavity that has no electric field on the surface was employed in these studies. The cavity shape concentrates the magnetic field on one flat surface where the test material is placed. The materials tested in this study have included oxygen free electronic grade copper, copper zirconium, copper chromium, hot isostatically pressed copper, single crystal copper, electroplated copper, Glidcop®, copper silver, and silver plated copper. The samples were exposed to different machining and heat treatment processes prior to rf processing. Each sample was tested to a peak pulsed heating temperature of approximately 110°C and remained at this temperature for approximately 10×106 rf pulses. In general, the results showed the possibility of pushing the gradient limits due to pulsed heating fatigue by the use of copper zirconium and copper chromium alloys.

  8. Deep-heating characteristics of an RF capacitive heating device.

    PubMed

    Kato, H; Hiraoka, M; Nakajima, T; Ishida, T

    1985-01-01

    An RF capacitive heating device was constructed and its deep-heating characteristics were studied using three mini-pigs. The deep-heating ability of RF capacitive heating was found to be improved by enlarging the electrodes, driving at 8 MHz, cooling the skin under the electrodes, inserting a bolus between the body and the electrodes and considering the anatomical structure of the body. The heating characteristics obtained were as follows. When applicators were placed on both sides of the abdomen of a mini-pig, 7 mm in fat layer thickness and 23 cm in lateral chest thickness, the increase in temperature of the deep part was greater than that of the fat layer. When applicators were placed on the posterior and anterior abdomen, overheating was noted in the fat and muscle near the back. The temperature was highest in a mock tumour, made by blocking blood flow to the spleen. The bio-heat equation revealed that RF capacitive heating accompanied by surface cooling at 10 degrees C could heat the deep portion of the body to 42 degrees C without excessive heating of a 1.6 cm thick fat layer.

  9. RF plasma heating improvement with EBG surfaces

    NASA Astrophysics Data System (ADS)

    Guadamuz, Saul; Milanesio, Daniele; Maggiora, Riccardo

    2008-11-01

    High impedance surfaces or electromagnetic band gap (EBG) surfaces have proved themselves to be useful in wireless communications applications due to their unique characteristics such as no propagating surface wave support, no conduction of RF current for a given bandwidth, in-phase electromagnetic reflection and non-inverted image of the electric charge in front of them [1]. These characteristics make possible to design compact antennas achieving better performance in terms of radiation and input impedance. ICRF plasma heating antennas in fusion experiments can take advantage of using EBG surfaces. One of the main issues in ICRF plasma heating is the low power coupling of the plasma facing antenna. The adoption of EBG surfaces in the antenna structure and the advantages offered by a predictive designing tool as TOPICA [2] offer the possibility to improve significantly the coupled power to plasma. [1] IEEE Trans. Microwave Theory Tech., vol. 47, pp. 2059--2074, Nov. 1999. [2] Nucl. Fusion, 46 (2006) S476.

  10. Plasma rotation and rf heating in DIII-D

    SciTech Connect

    DeGrassie, J. S.; Baker, D. R.; Burrell, K. H.; Greenfield, C. M.; Lin-Liu, Y. R.; Luce, T. C.; Petty, C. C.; Prater, R.; Heidbrink, W. W.; Rice, B. W.

    1999-09-20

    In a variety of discharge conditions on DIII-D it is observed that rf electron heating reduces the toroidal rotation speed and core ion temperature. The rf heating can be with either fast wave or electron cyclotron heating and this effect is insensitive to the details of the launched toroidal wavenumber spectrum. To date all target discharges have rotation first established with co-directed neutral beam injection. A possible cause is enhanced ion momentum and thermal diffusivity due to electron heating effectively creating greater anomalous viscosity. Another is that a counter directed toroidal force is applied to the bulk plasma via rf driven radial current.

  11. Plasma rotation and rf heating in DIII-D

    SciTech Connect

    Grassie, J. S. de; Baker, D. R.; Burrell, K. H.; Greenfield, C. M.; Lin-Liu, Y. R.; Luce, T. C.; Petty, C. C.; Prater, R.; Heidbrink, W. W.; Rice, B. W.

    1999-09-20

    In a variety of discharge conditions on DIII-D it is observed that rf electron heating reduces the toroidal rotation speed and core ion temperature. The rf heating can be with either fast wave or electron cyclotron heating and this effect is insensitive to the details of the launched toroidal wavenumber spectrum. To date all target discharges have rotation first established with co-directed neutral beam injection. A possible cause is enhanced ion momentum and thermal diffusivity due to electron heating effectively creating greater anomalous viscosity. Another is that a counter directed toroidal force is applied to the bulk plasma via rf driven radial current. (c) 1999 American Institute of Physics.

  12. Possible high power limitations from RF pulsed heating

    NASA Astrophysics Data System (ADS)

    Pritzkau, David P.; Bowden, Gordon B.; Menegat, Al; Siemann, Robert H.

    1999-05-01

    One of the possible limitations to achieving high power in RF structures is damage to metal surfaces due to RF pulsed heating. Such damage may lead to degradation of RF performance. An experiment to study RF pulsed heating on copper has been developed at SLAC. The experiment consists of operating two pillbox cavities in the TE011 mode using a 50 MW X-Band klystron. The estimated temperature rise of the surface of copper is 350 °C for a power input of 20 MW to each cavity with a pulse length of 1.5 μs. Preliminary results from an experiment performed earlier are presented. A revised design for continued experiments is also presented along with relevant theory and calculations.

  13. Reducing the Heat Load on the LCLS 120 Hz RF Gun with RF Pulse Shaping

    SciTech Connect

    Schmerge, J.

    2005-01-31

    The LCLS injector must operate at 120 Hz repetition frequency but to date the maximum operating frequency of an S-band rf gun has been 50 Hz. The high fields desired for the LCLS gun operation limit the repetition frequency due to thermal expansion causing rf detuning and field redistribution. One method of addressing the thermal loading problem is too reduce the power lost on the cavity walls by properly shaping the rf pulse incident on the gun. The idea is to reach the steady state field value in the gun faster than the time constant of the gun would allow when using a flat incident rf pulse. By increasing the incident power by about a factor of three and then decreasing the incident power when the field reaches the desired value in the gun, the field build up time can be decreased by more than a factor of three. Using this technique the heat load is also decreased by more than a factor of three. In addition the rf coupling coefficient can be increased from the typical critically coupled designs to an overcoupled design which also helps reduce the field build up time. Increasing the coupling coefficient from 1 to 2 reduces the heat load by another 25% and still limits the reflected power and coupling hole size to manageable levels.

  14. Heating of Particulates by RF Magnetic Field and RF Electric Field

    NASA Astrophysics Data System (ADS)

    Tang, Wilkin; Bosman, Herman; Lau, Y. Y.; Gilgenbach, R. M.

    2004-11-01

    Microwave heating is an important industrial heating process for certain niche applications such as the sintering of ceramics and rubber vulcanization, and has potential uses in the treatment of mineral ores, heating of reagents and catalysts in chemical reactions, and regeneration of molecular sieves. Here, we examine microwave heating by placing a small, spherical particulate of a general complex permittivity and permeability at the center of a perfectly conducting spherical cavity. The dispersion relation for both the TE mode and TM mode is solved exactly. The damping rates of these modes immediately give the degree of absorption by the rf electric field and by the rf magnetic field, over a wide range of parameters, and from quasi-static to very high frequencies. It is found that, in general, whenever the resistive skin depth is much less than the radius of the particulate, heating by the rf magnetic field always dominates, whether the particulate is magnetic or nonmagnetic. Simple scaling laws have been derived and will be presented [H. Bosman et al., APL (to be published)].

  15. RF heating for fusion product studies

    SciTech Connect

    Hellsten, T. Johnson, T.; Sharapov, S. E.; Kiptily, V.; Rimini, F.; Eriksson, J.; Mantsinen, M.; Schneider, M.; Tsalas, M.

    2015-12-10

    Third harmonic cyclotron heating is an effective tool for accelerating deuterium (D) beams to the MeV energy range, suitable for studying ITER relevant fast particle physics in plasmas without significant tritium content. Such experiments were recently conducted in JET with an ITER like wall in D plasmas with {sup 3}He concentrations up to 30% in order to boost the fusion reactivity by D-{sup 3}He reactions. The harmonic cyclotron heating produces high-energy tails in the MeV range of D ions by on-axis heating and of {sup 3}He ions by tangential off-axis heating. The discharges are characterized by long sawtooth free periods and a rich spectrum of MHD modes excited by the fast D and {sup 3}He ions. The partitions of the power, which depend on the distribution function of D, vary strongly over several slowing down times. Self-consistent modelling of the distribution function with the SELFO-light code are presented and compared with experimental data from fast particle diagnostics.

  16. RF heating for fusion product studies

    NASA Astrophysics Data System (ADS)

    Hellsten, T.; Johnson, T.; Sharapov, S. E.; Kiptily, V.; Eriksson, J.; Mantsinen, M.; Schneider, M.; Rimini, F.; Tsalas, M.

    2015-12-01

    Third harmonic cyclotron heating is an effective tool for accelerating deuterium (D) beams to the MeV energy range, suitable for studying ITER relevant fast particle physics in plasmas without significant tritium content. Such experiments were recently conducted in JET with an ITER like wall in D plasmas with 3He concentrations up to 30% in order to boost the fusion reactivity by D-3He reactions. The harmonic cyclotron heating produces high-energy tails in the MeV range of D ions by on-axis heating and of 3He ions by tangential off-axis heating. The discharges are characterized by long sawtooth free periods and a rich spectrum of MHD modes excited by the fast D and 3He ions. The partitions of the power, which depend on the distribution function of D, vary strongly over several slowing down times. Self-consistent modelling of the distribution function with the SELFO-light code are presented and compared with experimental data from fast particle diagnostics.

  17. Continued development of modeling tools and theory for RF heating

    SciTech Connect

    1998-12-01

    Mission Research Corporation (MRC) is pleased to present the Department of Energy (DOE) with its renewal proposal to the Continued Development of Modeling Tools and Theory for RF Heating program. The objective of the program is to continue and extend the earlier work done by the proposed principal investigator in the field of modeling (Radio Frequency) RF heating experiments in the large tokamak fusion experiments, particularly the Tokamak Fusion Test Reactor (TFTR) device located at Princeton Plasma Physics Laboratory (PPPL). An integral part of this work is the investigation and, in some cases, resolution of theoretical issues which pertain to accurate modeling. MRC is nearing the successful completion of the specified tasks of the Continued Development of Modeling Tools and Theory for RF Heating project. The following tasks are either completed or nearing completion. (1) Anisotropic temperature and rotation upgrades; (2) Modeling for relativistic ECRH; (3) Further documentation of SHOOT and SPRUCE. As a result of the progress achieved under this project, MRC has been urged to continue this effort. Specifically, during the performance of this project two topics were identified by PPPL personnel as new applications of the existing RF modeling tools. These two topics concern (a) future fast-wave current drive experiments on the large tokamaks including TFTR and (c) the interpretation of existing and future RF probe data from TFTR. To address each of these topics requires some modification or enhancement of the existing modeling tools, and the first topic requires resolution of certain theoretical issues to produce self-consistent results. This work falls within the scope of the original project and is more suited to the project`s renewal than to the initiation of a new project.

  18. A Shuttle/SpaceLab RF environment survey facility

    NASA Technical Reports Server (NTRS)

    Taylor, R. E.; Prince, R. E.; Mcgregor, D. N.

    1974-01-01

    This paper describes some of the basic system considerations of a proposed experiment for monitoring and measuring the global electromagnetic radiation environment. RF spectrum coverage for this spaceborne survey facility is anticipated to be quite broad and will include selected frequency bands ranging from UHF to millimeter waves. By establishing this RF environment survey facility, a broad data base of useful electromagnetic field intensity information will be developed. This, in turn, should help both the regulatory agencies and user community in terms of future frequency planning and system design by avoiding unwarranted interference. It is proposed that this experiment be flown as a future test bed during the Shuttle/Spacelab era for continuously gathering and updating information on earth-emitted electromagnetic emissions on a global scale.

  19. RF Current Drive and Heating Experiments on MST

    NASA Astrophysics Data System (ADS)

    Thomas, M. A.; Anderson, J. K.; Burke, D. R.; Forest, C. B.; Goetz, J. A.; Hendries, E. R.; Kaufman, M. C.; Seltzman, A. H.; Diem, S. J.; Harvey, R. W.

    2011-10-01

    Two rf schemes are being studied on the MST reversed field pinch for possible use in current profile control experiments. MHD modeling has shown that externally driven off-axis parallel current can improve stability of the dominant core tearing modes. Coupling experiments at the 100 kW level with lower hybrid (LH) and electron Bernstein waves (EBW) both show soft x-ray emission consistent with rf heating of electrons, and a small driven current in the LH case. Computational work in both cases suggests that, for sufficiently low energetic electron diffusivity, between 2 and 5 MW should drive enough current for mode stabilization. A 1 MW EBW system is under construction, with a compact antenna allowing variable polarization. A decision on higher power LH development will follow tests of a repaired antenna. Status and results of power and coupling tests will be presented.

  20. Self-generated stochastic heating in an rf discharge

    SciTech Connect

    Lichtenberg, A.

    1992-01-01

    We have studied the nonlinear dynamics of stochastic heating arising from the reflection of electrons from moving sheaths as an underlying mechanism for electron power deposition in r.f. discharges. We examined the dynamics of the electron collision with the sheaths in the regime in which the sheath motion is small compared to the average electron velocity to de rive a mop that describes the electron motion. We have shown that for high frequency, ({omega}/2{pi}{approx gt}50MHz), the electrons will strike the moving wall with random phase. At low pressures this stochasticity is an intrinsic property of the dynamics. The stochastic electron heating leads to a power law electron distribution. The stochastic heating was determined in both the slow sheath and fast sheath velocity regimes assuming an incident Maxwellian distribution.

  1. HEAT TRANSFER ANALYSIS FOR FIXED CST AND RF COLUMNS

    SciTech Connect

    Lee, S

    2007-10-17

    In support of a small column ion exchange (SCIX) process for the Savannah River Site waste processing program, transient and steady state two-dimensional heat transfer models have been constructed for columns loaded with cesium-saturated crystalline silicotitanate (CST) or spherical Resorcinol-Formaldehyde (RF) beads and 6 molar sodium tank waste supernate. Radiolytic decay of sorbed cesium results in heat generation within the columns. The models consider conductive heat transfer only with no convective cooling and no process flow within the columns (assumed column geometry: 27.375 in ID with a 6.625 in OD center-line cooling pipe). Heat transfer at the column walls was assumed to occur by natural convection cooling with 35 C air. A number of modeling calculations were performed using this computational heat transfer approach. Minimal additional calculations were also conducted to predict temperature increases expected for salt solution processed through columns of various heights at the slowest expected operational flow rate of 5 gpm. Results for the bounding model with no process flow and no active cooling indicate that the time required to reach the boiling point of {approx}130 C for a CST-salt solution mixture containing 257 Ci/liter of Cs-137 heat source (maximum expected loading for SCIX applications) at 35 C initial temperature is about 6 days. Modeling results for a column actively cooled with external wall jackets and the internal coolant pipe (inlet coolant water temperature: 25 C) indicate that the CST column can be maintained non-boiling under these conditions indefinitely. The results also show that the maximum temperature of an RF-salt solution column containing 133 Ci/liter of Cs-137 (maximum expected loading) will never reach boiling under any conditions (maximum predicted temperature without cooling: 88 C). The results indicate that a 6-in cooling pipe at the center of the column provides the most effective cooling mechanism for reducing the

  2. Performance predictions of RF heated plasma in EAST

    NASA Astrophysics Data System (ADS)

    Ding, S.; Wan, B.; Zhang, X.; Budny, R. V.; Guo, Y.; McCune, D.; Xu, P.; Yang, J.; Qian, J.; Shi, Y.; Wang, F.; Kaye, S. M.

    2011-01-01

    Scenario development of high power L- and H-mode plasmas in the Experimental Advanced Superconducting Tokamak (EAST) tokamak is reported. The simulations use PTRANSP in combination with TSC to explore EAST plasmas with various radio frequency (RF) auxiliary heating methods, including ion cyclotron resonant heating (ICRH) and lower hybrid current drive. The GLF23 transport model is found to give a better fit to temperature measurements compared with the MMM95 and MMM08 models. A series of ICRH simulations are performed to optimize parameters of a new ICRH system in EAST. The highest plasma stored energy and other related plasma parameters using the current auxiliary power limits are predicted. The discharge length of high power plasma can be 8-200 s, depending on the volt-second consumption in different scenarios. Various phenomena are reported including the influence of different fractions of RF power on their deposition behavior, and on thermal diffusivity, the linear relation between q0 and LHW power fraction, different behavior of fast ions between L- and H-mode plasmas. The scenario development is predicted to improve the performance of EAST.

  3. RF-sheath heat flux estimates on Tore Supra and JET ICRF antennae. Extrapolation to ITER

    SciTech Connect

    Colas, L.; Portafaix, C.; Goniche, M.; Jacquet, Ph.

    2009-11-26

    RF-sheath induced heat loads are identified from infrared thermography measurements on Tore Supra ITER-like prototype and JET A2 antennae, and are quantified by fitting thermal calculations. Using a simple scaling law assessed experimentally, the estimated heat fluxes are then extrapolated to the ITER ICRF launcher delivering 20 MW RF power for several plasma scenarios. Parallel heat fluxes up to 6.7 MW/m{sup 2} are expected very locally on ITER antenna front face. The role of edge density on operation is stressed as a trade-off between easy RF coupling and reasonable heat loads. Sources of uncertainty on the results are identified.

  4. Survey of chaos in the rf-biased Josephson junction

    SciTech Connect

    Kautz, R.L.; Monaco, R.

    1985-02-01

    Chaotic behavior in the rf-biased Josephson junction is studied through digital simulations of the Steward--McCumber model. Chaotic states are characterized by Poincare sections, Liapunov exponents, and power spectra. Models are presented which explain some features of the chaotic spectra. The parameter range over which chaotic behavior occurs is determined empirically for a broad range of dc bias, rf bias, and hysteresis parameters for a fixed rf frequency. It is shown that chaos does not occur if either the dc bias or the rf bias is very large. An attempt is made to explain the boundaries of the chaotic region in terms of simple models for chaotic behavior.

  5. Convex optimization of MRI exposure for mitigation of RF-heating from active medical implants

    NASA Astrophysics Data System (ADS)

    Córcoles, Juan; Zastrow, Earl; Kuster, Niels

    2015-09-01

    Local RF-heating of elongated medical implants during magnetic resonance imaging (MRI) may pose a significant health risk to patients. The actual patient risk depends on various parameters including RF magnetic field strength and frequency, MR coil design, patient’s anatomy, posture, and imaging position, implant location, RF coupling efficiency of the implant, and the bio-physiological responses associated with the induced local heating. We present three constrained convex optimization strategies that incorporate the implant’s RF-heating characteristics, for the reduction of local heating of medical implants during MRI. The study emphasizes the complementary performances of the different formulations. The analysis demonstrates that RF-induced heating of elongated metallic medical implants can be carefully controlled and balanced against MRI quality. A reduction of heating of up to 25 dB can be achieved at the cost of reduced uniformity in the magnitude of the B1+ field of less than 5%. The current formulations incorporate a priori knowledge of clinically-specific parameters, which is assumed to be available. Before these techniques can be applied practically in the broader clinical context, further investigations are needed to determine whether reduced access to a priori knowledge regarding, e.g. the patient’s anatomy, implant routing, RF-transmitter, and RF-implant coupling, can be accepted within reasonable levels of uncertainty.

  6. Convex optimization of MRI exposure for mitigation of RF-heating from active medical implants.

    PubMed

    Córcoles, Juan; Zastrow, Earl; Kuster, Niels

    2015-09-21

    Local RF-heating of elongated medical implants during magnetic resonance imaging (MRI) may pose a significant health risk to patients. The actual patient risk depends on various parameters including RF magnetic field strength and frequency, MR coil design, patient's anatomy, posture, and imaging position, implant location, RF coupling efficiency of the implant, and the bio-physiological responses associated with the induced local heating. We present three constrained convex optimization strategies that incorporate the implant's RF-heating characteristics, for the reduction of local heating of medical implants during MRI. The study emphasizes the complementary performances of the different formulations. The analysis demonstrates that RF-induced heating of elongated metallic medical implants can be carefully controlled and balanced against MRI quality. A reduction of heating of up to 25 dB can be achieved at the cost of reduced uniformity in the magnitude of the B(1)(+) field of less than 5%. The current formulations incorporate a priori knowledge of clinically-specific parameters, which is assumed to be available. Before these techniques can be applied practically in the broader clinical context, further investigations are needed to determine whether reduced access to a priori knowledge regarding, e.g. the patient's anatomy, implant routing, RF-transmitter, and RF-implant coupling, can be accepted within reasonable levels of uncertainty. PMID:26350025

  7. Generation of whistler-wave heated discharges with planar resonant RF networks.

    PubMed

    Guittienne, Ph; Howling, A A; Hollenstein, Ch

    2013-09-20

    Magnetized plasma discharges generated by a planar resonant rf network are investigated. A regime transition is observed above a magnetic field threshold, associated with rf waves propagating in the plasma and which present the characteristics of whistler waves. These wave heated regimes can be considered as analogous to conventional helicon discharges, but in planar geometry.

  8. MRI thermometry: Fast mapping of RF-induced heating along conductive wires.

    PubMed

    Ehses, Philipp; Fidler, Florian; Nordbeck, Peter; Pracht, Eberhard D; Warmuth, Marcus; Jakob, Peter M; Bauer, Wolfgang R

    2008-08-01

    Conductive implants are in most cases a strict contraindication for MRI examinations, as RF pulses applied during the MRI measurement can lead to severe heating of the surrounding tissue. Understanding and mapping of these heating effects is therefore crucial for determining the circumstances under which patient examinations are safe. The use of fluoroptic probes is the standard procedure for monitoring these heating effects. However, the observed temperature increase is highly dependent on the positioning of such a probe, as it can only determine the temperature locally. Temperature mapping with MRI after RF heating can be used, but cooling effects during imaging lead to a significant underestimation of the heating effect. In this work, an MRI thermometry method was combined with an MRI heating sequence, allowing for temperature mapping during RF heating. This technique may provide new opportunities for implant safety investigations.

  9. An amplitude and phase control system for the TFTR rf heating sources

    SciTech Connect

    Cutsogeorge, G.

    1989-04-01

    Feedback loops that control the amplitude and phase of the rf heating sources on TFTR are described. The method for providing arc protection is also discussed. Block diagrams and Bode plots are included. 6 figs.

  10. Experimental investigation of heating phenomena in linac mechanical interfaces due to RF field penetration

    SciTech Connect

    Fazio, M.V.; Reid, D.W.; Potter, J.M.

    1981-01-01

    In a high duty-factor, high-current, drift-tube linear accelerator, a critical interface exists between the drift-tube stem and the tank wall. This interface must provide vacuum integrity and RF continuity, while simultaneously allowing alignment flexibility. Because of past difficulties with RF heating of vacuum bellows and RF joints encountered by others, a paucity of available information, and the high reliability requirement for the Fusion Materials Irradiation Test (FMIT) accelerator, a program was initiated to study the problem. Because RF heating is the common failure mode, an attempt was made to find a correlation between the drift-tube-stem/linac-tank interface geometry and RF field penetration from the tank into the interface region. Experiments were performed at 80 MHz on an RF structure designed to simulate the conditions to which a drift-tube stem and vacuum bellows are exposed in a drift-tube linac. Additional testing was performed on a 367-MHz model of the FMIT prototype drift-tube linac. Experimental results, and a method to predict excessive RF heating, is presented. An experimentally tested solution to the problem is discussed.

  11. Balanced-line rf electrode system for use in rf ground heating to recover oil from oil shale

    SciTech Connect

    Edelstein, W.A.; Vinegar, H.J.; Chiafu Hsu; Mueller, O.M.

    1993-08-17

    A system is described for extracting oil in-situ from a hydrocarbon bearing layer below a surface layer comprising: (a) a master oscillator for producing a fundamental frequency; (b) a plurality of heating sources, each comprising: radiofrequency (RF) producing means for providing a radiofrequency excitation signal based upon the fundamental frequency, a coaxial line coupled to the RF producing means for passing the radiofrequency signal through said surface layer without substantial loss of power; a conductive electrode located in the hydrocarbon bearing layer having a length related to the radiofrequency signal and adapted for radiating energy into said hydrocarbon bearing layer for causing shade oil to be extracted; a plurality of matching elements, each matching element coupled, respectively, between each respective electrode and a respective coaxial line for maximizing radiation emitted by the electrodes when they receive the radiofrequency signal; and (c) a plurality of producer wells adapted for collecting the extracted shale oil.

  12. Reduction of Ag–Si electrical contact resistance by selective RF heating

    NASA Astrophysics Data System (ADS)

    de Wijs, W.-J. A.; Ljevar, S.; van de Sande, M. J.; de With, G.

    2016-06-01

    Fast and selective inductive heating of pre-sintered silver lines on silicon as present in solar cells using 27 MHz radio-frequency inductive fields is shown. IR measurements of silicon substrates show that above 450 °C the heating rate of the samples increases sharply, indicating that both the silver and the silicon are heated. By moving the substrate with respect to the RF antenna and modulation of the RF field, silicon wafers were heated reproducibly above 450 °C with heating rates in excess of 200 °C s‑1. Furthermore, selective heating of lines of pre-sintered silver paste was shown below the 450 °C threshold on silicon substrates. The orientation of the silver tracks relative to the RF antenna appeared to be crucial for homogeneity of heating. Transmission line measurements show a clear effect on contact formation between the silver lines and the silicon substrate. To lower the contact resistance sufficiently for industrial feasibility, a high temperature difference between the Si substrate and the Ag tracks is required. The present RF heating process does not match the time scale needed for contact formation between silver and silicon sufficiently, but the significantly improved process control achieved shows promise for applications requiring fast heating and cooling rates.

  13. 3D finite element model of RF heating: novel nonablative cutaneous therapy

    NASA Astrophysics Data System (ADS)

    Pham, Linda; Pope, Karl A.

    2003-06-01

    This study presents a finite element model of a non-ablative RF tissue heating system for dermatological applications. The Thermage ThermaCool TC System consists of a capacitively coupled treatment tip, handpiece, RF generator, and cryogen delivery system. Various electrode geometries were created to generate uniform thermal profiles at specific depths in the tissue. The optimal thermal treatment depth for a clinical indication is influenced by factors such as tissue thickness for a given anatomical location, the desired target for heating in that tissue, and anesthesia factors. Electrodes of ¼, 1, and 1½cm2 area were evaluated for depth of treatment. A 3D multi-physics finite element model was developed to simulate RF heating in tissue. The program coupled electrical and thermal models to predict the electric field produced and the consequent heating. The electrical portion of the model was verified using an electric field mapping system. The thermal section of the model was confirmed via thermocouple measurements for cooling and infrared imaging measurements for RF heating. The FEM model produced electrical and thermal predictions that were verified with experimental measurements. The finite element model shows significant potential as a predictive R&D tool to assist in RF electrode design and reduce product development time.

  14. FREQUENCY CONTROL OF RF HEATING OF GASEOUS PLASMA

    DOEpatents

    Herold, E.W.

    1962-09-01

    This invention relates to the heating of gaseous plasma by radiofrequency ion-cyclotron resonance heating. The cyclotron resonance frequencies are varied and this invention provides means for automatically controlling the frequency of the radiofrequency to maximize the rate of heating. To this end, a servo-loop is provided to sense the direction of plasma heating with frequency and a control signal is derived to set the center frequency of the radiofrequency energy employed to heat the plasma. (AEC)

  15. A flexible RF applicator for heating viscous lossy products such as foods.

    PubMed

    Roussy, G; Streiff, F; Moneuse, M

    2001-01-01

    A helical RF industrial applicator was evaluated for heating minced meat flowing in a hollow tube. Heating was homogeneous inside the product, although the product was highly lossy due to its high electric conductivity. The homogeneity was much better than could be obtained with microwave heating. A high power density, up to 5 kW/liter, can be deposited inside the product with 95% efficiency.

  16. Present and future status of noninvasive selective deep heating using RF in hyperthermia.

    PubMed

    Kato, H; Ishida, T

    1993-07-01

    To achieve hyperthermia using electromagnetic energy, RF of under 100 MHz is basically suitable for the external heating of the deep portions of the body. For applicators using such RF, the following types are considered: capacitive, inductive, radiative and hybrid. With radiative applicators, the intensity of the EM waves radiated from the applicator decreases with propagation into the material to be heated, but the phased annular array of radiative applicators potentially increases the intensity of the EM energy in the deep portion owing to the interference of the waves. Using this method, the focusing of EM energy depends on the dielectric properties of the material to be heated. With respect to RF heating at a lower frequency than the RF used for the annular phased array, some devices have been said to concentrate EM energy in the deep portions, where the characteristics of 'wave' are not utilised. To this end, some methods using capacitive electrodes, an inductive coil, or a combination of both, are being designed. The results of using such methods have shown that it is possible to supply sufficient EM energy to the muscle layers deep in the material to be heated, without heating the fat layers excessively.

  17. On RF heating of inhomogeneous collisional plasma under ion-cyclotron resonance conditions

    SciTech Connect

    Timofeev, A. V.

    2015-11-15

    During ion-cyclotron resonance (ICR) heating of plasma by the magnetic beach method, as well as in some other versions of ICR heating, it is necessary to excite Alfvén oscillations. In this case, it is difficult to avoid the phenomenon of the Alfvén resonance, in which Alfvén oscillations transform into lower hybrid oscillations. The latter efficiently interact with electrons, due to which most of the deposited RF energy is spent on electron (rather than ion) heating. The Alfvén resonance takes place due to plasma inhomogeneity across the external magnetic field. Therefore, it could be expected that variations in the plasma density profile would substantially affect the efficiency of the interaction of RF fields with charged particles. However, the results obtained for different plasma density profiles proved to be nearly the same. In the present work, a plasma is considered the parameters of which correspond to those planned in future ICR plasma heating experiments on the PS-1 facility at the Kurchatov Institute. When analyzing the interaction of RF fields with charged particles, both the collisionless resonance interaction and the interaction caused by Coulomb collisions are taken into account, because, in those experiments, the Coulomb collision frequency will be comparable with the frequency of the heating field. Antennas used for ICR heating excite RF oscillations with a wide spectrum of wavenumbers along the magnetic field. After averaging over the spectrum, the absorbed RF energy calculated with allowance for collisions turns out to be close to that absorbed in collisionless plasma, the energy fraction absorbed by electrons being substantially larger than that absorbed by ions.

  18. An RF heated tandem mirror plasma propulsion study

    SciTech Connect

    Yang, T.F.; Yao, X.; Peng, S.; Krueger, W.A.; Chang-Diaz, F.R.

    1989-01-01

    Experimental results on a tandem mirror hybrid plume rocket involving a three-stage system of plasma injection, heating, and subsequent injection through a magnetic nozzle are presented. In the experiments, a plasma is created by breaking down the gas with electron cyclotron resonance heating at 2 kW in the central cell, and the ion species is then heated to high temperatures with ion cyclotron resonance heating at 10 kW in the end cell. A Langmuir probe measured an electron density of 2.5 x 10 to the 16th/cu m and a temperature of 100 eV in the central cell and an ion density of 1.25 x 10 to the 17th/cu m and a temperature of 500 eV in the end cell. 6 refs.

  19. Advanced Synthesis of Spinnable MWCNT Forests by RF-Induction Heating Enhanced CVD Process

    NASA Astrophysics Data System (ADS)

    Zakhidov, Anvar; Holmes, William; UTD Solarno Team; Solarno UTD Team

    2015-03-01

    We demonstrate here an advanced method to effectively grow tall multi-wall carbon nanotubes (MWCNT) vertically oriented forests which are highly spinnable. Heating of the Fe catalyst is achieved extremely fast by RF induction heating using coils outside the quartz tube. This method and the new apparatus designed and presented in this paper allow separate control over the temperature of the substrate and the temperature of the incoming gases. In addition to temperature control, the fast T-ramping of the substrate preserves the catalyst nanoclusters from Ostwald ripening and other growth quenching effects such as carbon overgrowth of the catalyst. We show that the parametric sweet spot or bell curve of substrate spinnability can be increased significantly with this improved RF-CVD method. The catalyst nanoclusters also show a wide band of density arrangements that very positively effect spinnability and the drawing ratio. Drawing ratios can vary from 2 meters to 12 meters of sheets drawn from only 1cm of forest. RF-CVD method allows to grow fast (in several minuts) higher CNT forests at higher temperature of synthesis up to 800 K, and obtain dry-spinable CNTs, Characterization results of the samples created in the newRF-CVD system will be presented and compared to previous CNT sheet samples by conventional three-zone resistive heating CVD to measure the extent of property improvements of the CNT sheets and forests. Specifics of the experimental system will be addressed in detail and future property improvements and applications explored.

  20. RF HEATING OF MRI-ASSISTED CATHETER STEERING COILS FOR INTERVENTIONAL MRI

    PubMed Central

    Settecase, Fabio; Hetts, Steven W.; Martin, Alastair J.; Roberts, Timothy P. L.; Bernhardt, Anthony F.; Evans, Lee; Malba, Vincent; Saeed, Maythem; Arenson, Ronald L.; Kucharzyk, Walter; Wilson, Mark W.

    2010-01-01

    RATIONALE AND OBJECTIVES To assess magnetic resonance imaging (MRI) radiofrequency (RF) related heating of conductive wire coils used in magnetically steerable endovascular catheters. MATERIALS AND METHODS A 3-axis microcoil was fabricated onto a 1.8 Fr catheter tip. In vitro testing was performed in a 1.5 T MRI system using an agarose gel filled vessel phantom, a transmit/receive body RF coil and a steady state free precession (SSFP) pulse sequence, and a fluoroptic thermometry system. Temperature was measured without simulated blood flow at varying distances from magnet isocenter and varying flip angles. Additional experiments were performed with laser-lithographed single-axis microcoil-tipped microcatheters in air and in a saline bath with varied grounding of the microcoil wires. Preliminary in vivo evaluation of RF heating was performed in pigs at 1.5 T with coil-tipped catheters in various positions in the common carotid arteries with SSFP pulse sequence on and off, and under physiologic flow and zero flow conditions. RESULTS In tissue-mimicking agarose gel, RF heating resulted in a maximal temperature increase of 0.35°C after 15 minutes of imaging, 15 cm from magnet isocenter. For a single axis microcoil, maximal temperature increases were 0.73-1.91°C in air and 0.45-0.55°C in saline. In vivo, delayed contrast enhanced MRI revealed no evidence of vascular injury and histopathological sections from the common carotid arteries confirmed the lack of vascular damage. CONCLUSIONS Microcatheter tip microcoils for endovascular catheter steering in MRI experience minimal RF heating under the conditions tested. These data provide the basis for further in vivo testing of this promising technology for endovascular interventional MRI. PMID:21075019

  1. Observations of Anisotropic Ion Temperature during RF Heating in the NSTX Edge

    SciTech Connect

    T.M. Biewer; R.E. Bell; D.S. Darrow; C.K. Phillips; J.R. Wilson

    2003-05-19

    A new spectroscopic diagnostic on the National Spherical Torus Experiment (NSTX) measures the velocity distribution of ions in the plasma edge with both poloidal and toroidal views. An anisotropic ion temperature is measured during the presence of high power HHFW RF heating in He plasmas, with the poloidal T(sub)i roughly twice the toroidal T(sub)i. Moreover, the measured spectral distribution suggests that two populations have temperatures of 500 eV and 50 eV with rotation velocities of -50 km/s and -10 km/s, respectively. This bi-modal distribution is observed in both the toroidal and poloidal views (in both He II and C III ions), and is well correlated with the period of RF power application to the plasma. The temperature of the edge ions is observed to increase with the applied RF power, which was scanned between 0 and 4.3MW. The ion heating mechanism from HHFW RF power has not yet been identified.

  2. Clinical experience with thermotron RF-8 capacitive heating for bulky tumors: University of Minnesota experience.

    PubMed

    Lee, C K; Song, C W; Rhee, J G; Levitt, S H

    1989-05-01

    We conducted a phase I clinical trial of the feasibility of using the Thermotron RF-8, a capacitative heating device utilizing 8-MHz RF, for the treatment of deep-seated and bulky human tumors. Preclinical studies with agar phantoms demonstrated that deep heating can be achieved with this device when the electrode diameters are sufficiently large relative to the thickness of the heated object. In the clinical application of capacitive heating with radiofrequency, excessive heating of subcutaneous tissue has often been a problem. However, this could be minimized by continuous cooling of the subcutaneous fat with a 10 degrees C saline bolus, beginning more than 20 minutes prior to the start of heating. It was often possible to raise the temperature of deep-seated tumors even in obese patients by applying this pre-cooling method. The mean achieved temperature during 30 to 40 minutes of heating was higher than 42 degrees C and 40 degrees C to 42 degrees C in 26% and 50% of 58 tumors treated, respectively. A combination of hyperthermia (four to ten sessions, twice a week) with full-course or a limited dose of radiotherapy resulted in complete tumor remission in 7% of patients, and partial tumor remission in 50% of patients. In the full-course radiotherapy group, 69% of the tumors were judged to show complete or partial regression, and in the low-dose group, 43% of the tumors regressed completely or partially. Histologic examination of many of the tumors that did not regress showed massive necrosis, indicating that tumor size after hyperthermia is not an accurate criterion of the treatment result. Side effects were minimal, and vital sign changes during heating were insignificant. Our data, together with those reported by Japanese investigators, clearly demonstrated that hyperthermia with the Thermotron RF-8 in combination with radiotherapy is useful in treating deep-seated and bulky tumors that fail to respond to conventional treatment modalities.

  3. Modeling an RF Cold Crucible Induction Heated Melter with Subsidence

    SciTech Connect

    Grant L. Hawkes

    2004-07-01

    A method to reduce radioactive waste volume that includes melting glass in a cold crucible radio frequency induction heated melter has been investigated numerically. The purpose of the study is to correlate the numerical investigation with an experimental apparatus that in the above mentioned melter. Unique to this model is the subsidence of the glass as it changes from a powder to molten glass and drastically changes density. A model has been created that couples the magnetic vector potential (real and imaginary) to a transient startup of the melter process. This magnetic field is coupled to the mass, momentum, and energy equations that vary with time and position as the melt grows. The coupling occurs with the electrical conductivity of the glass as it rises above the melt temperature of the glass and heat is generated. Natural convection within the molten glass helps determine the shape of the melt as it progresses in time. An electromagnetic force is also implemented that is dependent on the electrical properties and frequency of the coil. This study shows the progression of the melt shape with time along with temperatures, power input, velocities and magnetic vector potential. Coupled to all of this is a generator that will be used for this lab sized experiment. The coupling with the 60 kW generator occurs with the impedance of the melt as it progresses and changes with time. A power controller has been implemented that controls the primary coil current depending on the power that is induced into the molten glass region.

  4. Recent experimental results of KSTAR RF heating and current drive

    SciTech Connect

    Wang, S. J. Kim, J.; Jeong, J. H.; Kim, H. J.; Joung, M.; Bae, Y. S.; Kwak, J. G.

    2015-12-10

    The overview of KSTAR activities on ICRH, LHCD and ECH/CD including the last experimental results and future plan aiming for long-pulse high-beta plasma will be presented. Recently we achieved reasonable coupling of ICRF power to H-mode plasma through several efforts to increase system reliability. Power balance will be discussed on this experiment. LHCD is still struggling in the low power regime. Review of antenna spectrum for the higher coupling in H-mode plasma will be tried. ECH/CD provides 41 sec, 0.8 MW of heating power to support high-performance long-pulse discharge. Also, 170 GHz ECH system is integrated with the Plasma Control System (PCS) for the feedback controlling of NTM. Status and plan of ECH/CD will be discussed. Finally, helicon current drive is being prepared for the next stage of KSTAR operation. The hardware preparation and the calculation results of helicon current drive in KSTAR plasma will be discussed.

  5. Recent experimental results of KSTAR RF heating and current drive

    NASA Astrophysics Data System (ADS)

    Wang, S. J.; Kim, J.; Jeong, J. H.; Kim, H. J.; Joung, M.; Bae, Y. S.; Kwak, J. G.

    2015-12-01

    The overview of KSTAR activities on ICRH, LHCD and ECH/CD including the last experimental results and future plan aiming for long-pulse high-beta plasma will be presented. Recently we achieved reasonable coupling of ICRF power to H-mode plasma through several efforts to increase system reliability. Power balance will be discussed on this experiment. LHCD is still struggling in the low power regime. Review of antenna spectrum for the higher coupling in H-mode plasma will be tried. ECH/CD provides 41 sec, 0.8 MW of heating power to support high-performance long-pulse discharge. Also, 170 GHz ECH system is integrated with the Plasma Control System (PCS) for the feedback controlling of NTM. Status and plan of ECH/CD will be discussed. Finally, helicon current drive is being prepared for the next stage of KSTAR operation. The hardware preparation and the calculation results of helicon current drive in KSTAR plasma will be discussed.

  6. Monitoring local heating around an interventional MRI antenna with RF radiometry

    SciTech Connect

    Ertürk, M. Arcan; El-Sharkawy, AbdEl-Monem M.; Bottomley, Paul A.

    2015-03-15

    Purpose: Radiofrequency (RF) radiometry uses thermal noise detected by an antenna to measure the temperature of objects independent of medical imaging technologies such as magnetic resonance imaging (MRI). Here, an active interventional MRI antenna can be deployed as a RF radiometer to measure local heating, as a possible new method of monitoring device safety and thermal therapy. Methods: A 128 MHz radiometer receiver was fabricated to measure the RF noise voltage from an interventional 3 T MRI loopless antenna and calibrated for temperature in a uniformly heated bioanalogous gel phantom. Local heating (ΔT) was induced using the antenna for RF transmission and measured by RF radiometry, fiber-optic thermal sensors, and MRI thermometry. The spatial thermal sensitivity of the antenna radiometer was numerically computed using a method-of-moment electric field analyses. The gel’s thermal conductivity was measured by MRI thermometry, and the localized time-dependent ΔT distribution computed from the bioheat transfer equation and compared with radiometry measurements. A “H-factor” relating the 1 g-averaged ΔT to the radiometric temperature was introduced to estimate peak temperature rise in the antenna’s sensitive region. Results: The loopless antenna radiometer linearly tracked temperature inside a thermally equilibrated phantom up to 73 °C to within ±0.3 °C at a 2 Hz sample rate. Computed and MRI thermometric measures of peak ΔT agreed within 13%. The peak 1 g-average temperature was H = 1.36 ± 0.02 times higher than the radiometric temperature for any media with a thermal conductivity of 0.15–0.50 (W/m)/K, indicating that the radiometer can measure peak 1 g-averaged ΔT in physiologically relevant tissue within ±0.4 °C. Conclusions: Active internal MRI detectors can serve as RF radiometers at the MRI frequency to provide accurate independent measures of local and peak temperature without the artifacts that can accompany MRI thermometry or

  7. Monitoring local heating around an interventional MRI antenna with RF radiometry

    PubMed Central

    Ertürk, M. Arcan; El-Sharkawy, AbdEl-Monem M.; Bottomley, Paul A.

    2015-01-01

    Purpose: Radiofrequency (RF) radiometry uses thermal noise detected by an antenna to measure the temperature of objects independent of medical imaging technologies such as magnetic resonance imaging (MRI). Here, an active interventional MRI antenna can be deployed as a RF radiometer to measure local heating, as a possible new method of monitoring device safety and thermal therapy. Methods: A 128 MHz radiometer receiver was fabricated to measure the RF noise voltage from an interventional 3 T MRI loopless antenna and calibrated for temperature in a uniformly heated bioanalogous gel phantom. Local heating (ΔT) was induced using the antenna for RF transmission and measured by RF radiometry, fiber-optic thermal sensors, and MRI thermometry. The spatial thermal sensitivity of the antenna radiometer was numerically computed using a method-of-moment electric field analyses. The gel’s thermal conductivity was measured by MRI thermometry, and the localized time-dependent ΔT distribution computed from the bioheat transfer equation and compared with radiometry measurements. A “H-factor” relating the 1 g-averaged ΔT to the radiometric temperature was introduced to estimate peak temperature rise in the antenna’s sensitive region. Results: The loopless antenna radiometer linearly tracked temperature inside a thermally equilibrated phantom up to 73 °C to within ±0.3 °C at a 2 Hz sample rate. Computed and MRI thermometric measures of peak ΔT agreed within 13%. The peak 1 g-average temperature was H = 1.36 ± 0.02 times higher than the radiometric temperature for any media with a thermal conductivity of 0.15–0.50 (W/m)/K, indicating that the radiometer can measure peak 1 g-averaged ΔT in physiologically relevant tissue within ±0.4 °C. Conclusions: Active internal MRI detectors can serve as RF radiometers at the MRI frequency to provide accurate independent measures of local and peak temperature without the artifacts that can accompany MRI thermometry or

  8. Characterization of the transition from collisional to stochastic heating in a RF discharge

    NASA Astrophysics Data System (ADS)

    Canal, G. P.; Luna, H.; Galvão, R. M. O.

    2010-01-01

    In this work, we have studied the transition from collisional to stochastic heating regime in a RF inductively coupled plasma discharge, in which the exciting antenna is placed inside the vacuum chamber. The electron and ion energy distribution functions are obtained using an RF filtered electrostatic probe and a Faraday cup. The analysis of the energy distribution functions as a function of the working pressure reveals the existence of two distinct discharge regimes, which are governed by the heating processes. Our results show that while the electron distribution function is Druyvesteyn-like for high pressures, p >= 4.0 × 10-2 mbar, it becomes bi-Druyvesteyn, and not bi-Maxwellian, as found in other works, for low pressures, p <= 1.0 × 10-2 mbar.

  9. Use of Near-Infrared Detector to Sense RF Antenna Heating

    SciTech Connect

    Legg, R.A.; Lee, R.L.; Baity, W.F.

    1999-11-01

    The three antennas used for ion cyclotron heating (ICH) experiments on DIII-D have experienced localized heating of the Faraday shield rods during plasma operations which has resulted in some melting. This melting is of great concern not only because of the damage it does to the rf system's ability to deliver rf to the plasma, but because of its potential to contaminate the plasma during a shot and cast the experimental results from the shot into question. A real-time sensor to detect the temperature of the antennae during plasma operations is described. The sensor uses an avalanche photo diode (APD) with sensitivity from 0.4 to 1.0 {micro}m to monitor the temperature of the antennae. Calculations for the detector sensitivity based on Planck's law are compared with experimental results and detector data taken during plasma operations are presented.

  10. Recent experimental results and modeling of RF heating of ({sup 3}He)-D JET plasmas: RF as a tool to study transport

    SciTech Connect

    Van Eester, D.; Lerche, E.; Marinoni, A.; Casati, A.; Joffrin, E.; Imbeaux, F.; Kiptily, V.; Sharapov, S.; Santala, M.; Giroud, C.; Crombe, K.; Andrew, Y.; Lomas, P.; Felton, R.

    2007-09-28

    D plasmas with {sup 3}He minorities have sharp, thin ion-ion hybrid layers that enable to efficiently excite short wavelength branches that are subsequently damped by fairly well localized electron Landau and TTMP absorption. Depending on the minority concentration chosen, ion minority heating or electron mode conversion damping is dominant. Recent experiments have been devoted to the study of ({sup 3}He)-D JET plasmas. One aspect of those experiments--using RF heating as a tool--is the study of the response of the plasma to RF power modulation, allowing to examine the fate of the RF power and to diagnose particle and energy transport. The present paper gives a very brief summary of a subset of these experiments. The focus will largely but not exclusively be on understanding ITB physics. The adopted probing methods are more generally applicable, though.

  11. Spatial distribution of RF-induced E-fields and implant heating in MRI.

    PubMed

    Nordbeck, Peter; Fidler, Florian; Weiss, Ingo; Warmuth, Marcus; Friedrich, Michael T; Ehses, Philipp; Geistert, Wolfgang; Ritter, Oliver; Jakob, Peter M; Ladd, Mark E; Quick, Harald H; Bauer, Wolfgang R

    2008-08-01

    The purpose of this study was to assess the distribution of RF-induced E-fields inside a gel-filled phantom of the human head and torso and compare the results with the RF-induced temperature rise at the tip of a straight conductive implant, specifically examining the dependence of the temperature rise on the position of the implant inside the gel. MRI experiments were performed in two different 1.5T MR systems of the same manufacturer. E-field distribution inside the liquid was assessed using a custom measurement system. The temperature rise at the implant tip was measured in various implant positions and orientations using fluoroptic thermometry. The results show that local E-field strength in the direction of the implant is a critical factor in RF-related tissue heating. The actual E-field distribution, which is dependent on phantom/body properties and the MR-system employed, must be considered when assessing the effects of RF power deposition in implant safety investigations.

  12. Neutron emission from JET DT plasmas with RF heating on minority hydrogen

    NASA Astrophysics Data System (ADS)

    Henriksson, H.; Conroy, S.; Ericsson, G.; Gorini, G.; Hjalmarsson, A.; Källne, J.; Tardocchi, M.; EFDA-JET Workprogramme, contributors to the

    2002-07-01

    The neutron emission spectrum from d+t→α+n reactions has been measured as a means to study the plasma response to radio frequency (RF) power coupled to hydrogen and deuteron minority components (through fundamental and second harmonic, respectively) in a tritium discharge at JET. The spectrum was measured with the magnetic proton recoil spectrometer and was analysed in terms of two spectral components due to thermal (TH) and high-energy (HE) deuterons interacting with the bulk ion population of thermal tritons. The results were used to derive information on the deuteron population in terms of temperatures (TTH and THE) as well as corresponding particle and kinetic energy densities of the plasma; the bulk ion temperature (Ti = TTH) was determined both before (with Ohmic heating only) and during the RF pulse. Similar information on protons was derived from other measurements in order to estimate the different RF effects on protons and deuterons. This paper illustrates qualitatively the type of empirical ion kinetic information that can be obtained from neutron emission spectroscopy; the data serves as a basis for comparison with results of predictive and interpretative models on RF effects in plasmas.

  13. Predictions of VRF on a Langmuir Probe under the RF Heating Spiral on the Divertor Floor on NSTX-U

    SciTech Connect

    Hosea, J C; Perkins, R J; Jaworski, M A; Kramer, G J; Ahn, J-W

    2014-07-01

    RF heating deposition spirals are observed on the divertor plates on NSTX as shown in for a NB plus RF heating case. It has been shown that the RF spiral is tracked quite well by the spiral mapping of the strike points on the divertor plate of magnetic field lines passing in front of the high harmonic fast wave (HHFW) antenna on NSTX. Indeed, both current instrumented tiles and Langmuir probes respond to the spiral when it is positioned over them. In particular, a positive increment in tile current (collection of electrons) is obtained when the spiral is over the tile. This current can be due to RF rectification and/or RF heating of the scrape off layer (SOL) plasma along the magnetic field lines passing in front of the the HHFW antenna. It is important to determine quantitatively the relative contributions of these processes. Here we explore the properties of the characteristics of probes on the lower divertor plate to determine the likelyhood that the primary cause of the RF heat deposition is RF rectification.

  14. Observations of Anisotropic Ion Temperature in the NSTX Edge during RF Heating

    SciTech Connect

    T.M. Biewer; R.E. Bell; J.R. Wilson; P.M. Ryan

    2004-10-21

    A new spectroscopic diagnostic on the National Spherical Torus Experiment (NSTX) measures the velocity distribution of ions in the plasma edge with both poloidal and toroidal views. An anisotropic ion temperature is measured during the presence of high-power high-harmonic fast-wave (HHFW) radio-frequency (RF) heating in helium plasmas, with the poloidal ion temperature roughly twice the toroidal ion temperature. Moreover, the measured spectral distribution suggests that two populations are present and have temperatures of 500 eV and 50 eV with rotation velocities of -50 km/s and -10 km/s, respectively. This bi-modal distribution is observed in both the toroidal and poloidal views (in both He{sup +} and C{sup 2+} ions), and is well correlated with the period of RF power application to the plasma. The temperature of the hot edge ions is observed to increase with the applied RF power, which was scanned between 0 and 4.3 MW. The ion heating mechanism is likely to be ion-Bernstein waves (IBW) from nonlinear decay of the launched HHFW.

  15. Feedback stabilization of magnetic islands by rf heating and current drive

    SciTech Connect

    Ignat, D.W.; Rutherford, P.H.; Hsuan, H.

    1985-11-01

    Feedback stabilization of the m = 2 mode in tokamaks would be advantageous for disruption-free operation at low q-values. Stabilization of the m = 1 mode and resulting ''sawteeth'' could lead to substantial increases in the stable ..beta..-value, as well as indirect stabilization of the m = 2 mode, by permitting q(0)-values below unity. Stabilization of these modes at acceptable amplitudes appears possible by feedback-modulated heating or current drive applied to the region within the mode-induced magnetic islands. Current drive offers by far the more efficient mechanism, and it can be accomplished using lower-hybrid or electron-cyclotron radio-frequency (rf) techniques. For the lower-hybrid case, ray-tracing calculations demonstrate the needed localization of the rf power, despite long ray paths in the toroidal direction. Top-launched lower-hybrid waves are favored for localized absorption.

  16. Toroidal Flow Generation by the ICRF Minority Heating and RF Wave Field Profile Dependence

    NASA Astrophysics Data System (ADS)

    Murakami, S.; Itoh, K.; Zheng, L. J.; Van Dam, J. W.; Fukuyama, A.

    2011-12-01

    The toroidal flow generation by the ICRF minority heating is investigated in the Alcator C-Mod like tokamak plasma applying GNET code, in which the drift kinetic equation is solved in 5D phase-space. An asymmetry of velocity distribution function in the parallel direction is found and two kinds of toroidal flows are observed. One is the sheared flow near the RF power absorption region depending on the sign of k∥ and the other is the toroidal flow, which is larger than the previous one, independent of the sign of k∥. It is found that the k∥ sign dependent flow would be related to the mechanism proposed by Ohkawa et al. [Phys. Plasmas 12 (2005) 094506.] and that the k∥ sign independent toroidal flow is generated by the net toroidal motion of energetic tail ions. We also investigate the effect of RF wave field profile on the toroidal flow generation comparing the local and broad heating cases. A broader toroidal flow is obtained and about 5 times of ICRF heating power is necessary for generating the similar amplitude of toroidal flow in the broad heating case.

  17. Cooperative clinical studies of hyperthermia using a capacitive type heating device GHT-RF8(Greenytherm).

    PubMed

    Loh, J J; Seong, J S; Suh, C O; Kim, G E; Chu, S S; Pak, K R; Lee, C G; Kim, B S; Kim, S G; Seel, D J

    1989-01-01

    Yonsei Cancer Center developed an RF(Radiofrequency) capacitive type heating device, GHT-RF8(Greenytherm) in cooperation with Green Cross Medical Corp., Korea in 1986 for the first time in Korea. Cooperative clinical studies of hyperthermia for the treatment of cancer using GHT-RF8 were conducted by Yonsei Cancer Center in collaboration with the Presbyterian Medical Center, Chonju, Korea. A total of forty patients with various histologically proven malignant tumors, including superficial (N = 13) and deep-seated tumors (N = 27), were treated with this newly developed heating device in conjunction with radiotherapy (N = 38) or chemotherapy (N = 2) at two different institutes between October 1986 and September 1987. These patients were locally far advanced or recurrent cases and considered to be refractory to conventional cancer treatment modalities. Radiotherapy was given in 200cGy per day, five times a week fractionations with a total tumor dose of 50-60Gy in 5-6 weeks. Within an hour after radiotherapy, the RF capacitive type of hyperthermia was given two times a week for a total of 4-10 treatment sessions and an attempt was made to maintain the tumor temperature at 41-45 degrees C for 30-60 minutes. Of forty patients treated, 14 patients with deep-seated tumors showed complete response and 20 patients showed partial response. The overall response rate was 85% (34 out of 40 patients) and only 6 patients showed no response. Complications from this treatment were mainly burns, superficial first degree burn in 2 cases, second degree in 4 cases and subcutaneous fat necrosis was observed in 2 cases.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Simulation of laser induced thermo-mechanical changes in tissue using RF heating method

    NASA Astrophysics Data System (ADS)

    Protsenko, Dmitriy E.; Zemek, Allison; Wong, Brian J. F.

    2007-02-01

    Successful application of laser cartilage reshaping (LCR) for the in-situ treatment of structural deformities in the nasal septum, external ear and trachea requires a better understanding of the evolution of cartilage mechanical properties with temperature. We develop a method of Radio Frequency (RF) heating for reliable evaluation of mechanical changes in septal cartilage undergoing heating and used obtained data to model the mechanical changes in cartilage at steady state following laser heating. Cartilage specimens harvested from porcine septum were secured between two flat parallel copper platens connected to a surgical radiofrequency source. The current was user-selectable and controlled to achieve any desired heating rate mimicking heating rate obtained during laser irradiation. Surface and internal temperatures were monitored by an IR camera and embedding a small electrically insulated thermocouple inside the specimen. Cylindrical and rectangular samples were fashioned from the heated specimens and their equilibrium elastic modulus was measured in a step unconfined compression and tension experiments, respectively. Functional dependencies of the elastic modulus and maximum temperature were interpolated from the measurements. The calculated elastic modulus profiles were incorporated into a numerical model of uniaxial unconfined compression and tension of laser irradiated samples. The reaction force to a 0.1 strain was calculated and compared with the reaction force obtained in analogous mechanical measurements experiment. The results of the numerical simulation of uniaxial compression of laser heated samples demonstrate good correlation with experimentally obtained reaction force. Generalization of this methodology to incorporate orthogonal mechanical properties may aid in optimizing clinical LCR procedures.

  19. Toroidal Rotation and Core Ion Confinement with RF Heating in DIII-D

    SciTech Connect

    deGrassie, J.S.; Greenfield, C.M.; Baker, D.R.; Burrell, K.H.; Lin-Liu, Y.R.; Lohr, J.; Luce, T.C.; Petty, C.C.; Prater, R.; Staebler, G.M.; Heidbrink, W.W.; Rice, B.W. Rice, Mau, T.K.; Porkolab, M.

    1999-07-01

    Shear in the E x B flow velocity can stabilize turbulent transport [1], and so it is of interest to understand the physics behind electric field generation and modification in the tokamak. In DIII-D the core radial electric field in many regimes is generated by flow velocities driven by momentum input from neutral beam injection (NBI). In a variety of conditions it is observed that direct electron heating is accompanied by a reduction in the NBI driven toroidal rotation velocity, U{sub {phi}}, and the ion temperature, T{sub i}, primarily in the core, {rho} <0.5 (where {rho} is a radial coordinate of the normalized toroidal flux). This electron heating can be done with either electron cyclotron heating (ECH) or fast wave electron heating (FWEH). Both can be accompanied by the reduction in U{sub {phi}} and T{sub i} [2-4]. Details of the parallel wavenumber (k//) spectrum of the launched rf do not seem to be important in either case for the effect to exist. Reductions are observed for EC waves launched with nonzero k// for current drive or launched radially with k//=0; and for FWEH with waves directed either co or counter, using the DIII-D four strap antennas [5], This universality indicates that increased electron temperature, T{sub e}, is increasing ion momentum and thermal transport, at least in the parameter regimes of these experiments. It is also possible that nonambipolar transport of resonantly heated particles is playing a role. To date, the great majority of the DIII-D experiments have been conducted with the rf target discharges driven by co-injected NBI.

  20. Experimental Investigation of RF Sheath Rectification in ICRF and LH Heated Plasmas on Alcator C-Mod

    SciTech Connect

    Ochoukov, R.; Whyte, D. G.; Faust, I.; LaBombard, B.; Lipschultz, B.; Meneghini, O.; Wallace, G.; Wukitch, S.; Myra, J.

    2011-12-23

    Radio frequency (RF) rectification of the plasma sheath is being actively studied on C-Mod as a likely mechanism that leads to prohibitively high molybdenum levels in the plasma core of ion cyclotron RF (ICRF) heated discharges. We installed emissive, ion sensitive, Langmuir, and 3-D B-dot probes to quantify the plasma potentials ({Phi}{sub P}) in ICRF and lower hybrid (LH) heated discharges. Two probe sets were mounted on fixed limiter surfaces and one set of probes was mounted on a reciprocating (along the major radius) probe. Initial results showed that RF rectification is strongly dependent on the local plasma density and not on the local RF fields. The RF sheaths had a threshold-like appearance at the local density of {approx}10{sup 16} m-{sup 3}. Radial probe scans revealed that the RF sheaths peaked in the vicinity of the ICRF limiter surface, agreeing with a recent theory. The highest {Phi}{sub P}'s were observed on magnetic field lines directly mapped to the active ICRF antenna. Measurements in LH heated plasmas showed a strong {Phi}{sub P} dependence on the parallel index of refraction n{sub ||} of the launched LH waves: {Phi}{sub P} is greater at lower n{sub ||}. Little dependence was observed on the local plasma density.

  1. Effect of insulating layer material on RF-induced heating for external fixation system in 1.5 T MRI system.

    PubMed

    Liu, Yan; Kainz, Wolfgang; Qian, Songsong; Wu, Wen; Chen, Ji

    2014-09-01

    The radio frequency (RF)-induced heating is a major concern when patients with medical devices are placed inside a magnetic resonance imaging (MRI) system. In this article, numerical studies are applied to investigate the potentials of using insulated materials to reduce the RF heating for external fixation devices. It is found that by changing the dielectric constant of the insulation material, the RF-induced heating at the tips of devices can be altered. This study indicates a potential technique of developing external fixation device with low MRI RF heating.

  2. Development of long pulse RF heating and current drive for H-mode scenarios with metallic walls in WEST

    SciTech Connect

    Ekedahl, Annika Bourdelle, Clarisse; Artaud, Jean-François; Bernard, Jean-Michel; Bufferand, Hugo; Colas, Laurent; Decker, Joan; Delpech, Léna; Dumont, Rémi; Goniche, Marc; Helou, Walid; Hillairet, Julien; Lombard, Gilles; Magne, Roland; Mollard, Patrick; Nardon, Eric; Peysson, Yves; Tsitrone, Emmanuelle

    2015-12-10

    The longstanding expertise of the Tore Supra team in long pulse heating and current drive with radiofrequency (RF) systems will now be exploited in the WEST device (tungsten-W Environment in Steady-state Tokamak) [1]. WEST will allow an integrated long pulse tokamak programme for testing W-divertor components at ITER-relevant heat flux (10-20 MW/m{sup 2}), while treating crucial aspects for ITER-operation, such as avoidance of W-accumulation in long discharges, monitoring and control of heat fluxes on the metallic plasma facing components (PFCs) and coupling of RF waves in H-mode plasmas. Scenario modelling using the METIS-code shows that ITER-relevant heat fluxes are compatible with the sustainment of long pulse H-mode discharges, at high power (up to 15 MW / 30 s at I{sub P} = 0.8 MA) or high fluence (up to 10 MW / 1000 s at I{sub P} = 0.6 MA) [2], all based on RF heating and current drive using Ion Cyclotron Resonance Heating (ICRH) and Lower Hybrid Current Drive (LHCD). This paper gives a description of the ICRH and LHCD systems in WEST, together with the modelling of the power deposition of the RF waves in the WEST-scenarios.

  3. Development of long pulse RF heating and current drive for H-mode scenarios with metallic walls in WEST

    NASA Astrophysics Data System (ADS)

    Ekedahl, Annika; Bourdelle, Clarisse; Artaud, Jean-François; Bernard, Jean-Michel; Bufferand, Hugo; Colas, Laurent; Decker, Joan; Delpech, Léna; Dumont, Rémi; Goniche, Marc; Helou, Walid; Hillairet, Julien; Lombard, Gilles; Magne, Roland; Mollard, Patrick; Nardon, Eric; Peysson, Yves; Tsitrone, Emmanuelle

    2015-12-01

    The longstanding expertise of the Tore Supra team in long pulse heating and current drive with radiofrequency (RF) systems will now be exploited in the WEST device (tungsten-W Environment in Steady-state Tokamak) [1]. WEST will allow an integrated long pulse tokamak programme for testing W-divertor components at ITER-relevant heat flux (10-20 MW/m2), while treating crucial aspects for ITER-operation, such as avoidance of W-accumulation in long discharges, monitoring and control of heat fluxes on the metallic plasma facing components (PFCs) and coupling of RF waves in H-mode plasmas. Scenario modelling using the METIS-code shows that ITER-relevant heat fluxes are compatible with the sustainment of long pulse H-mode discharges, at high power (up to 15 MW / 30 s at IP = 0.8 MA) or high fluence (up to 10 MW / 1000 s at IP = 0.6 MA) [2], all based on RF heating and current drive using Ion Cyclotron Resonance Heating (ICRH) and Lower Hybrid Current Drive (LHCD). This paper gives a description of the ICRH and LHCD systems in WEST, together with the modelling of the power deposition of the RF waves in the WEST-scenarios.

  4. MR safety: fast T₁ thermometry of the RF-induced heating of medical devices.

    PubMed

    Gensler, D; Fidler, F; Ehses, P; Warmuth, M; Reiter, T; Düring, M; Ritter, O; Ladd, M E; Quick, H H; Jakob, P M; Bauer, W R; Nordbeck, P

    2012-11-01

    Determining the MR compatibility of medical implants and devices is becoming increasingly relevant. In most cases, the heating of conductive implants due to radiefrequency (RF) excitation pulses is measured by fluoroptic temperature sensors in relevant tests for approval. Another common method to determine these heating effects is MR thermometry using the proton resonance frequency. This method gives good results in homogeneous phantoms. However in many cases, technical shortcomings such as susceptibility artifacts prohibit exact proton resonance frequency thermometry near medical implants. Therefore, this work aimed at developing a fast T₁-based method which allows controlled MR-related heating of a medical implant while simultaneously quantifying the spatial and temporal temperature distribution. To this end, an inversion recovery snapshot Fast Low-Angle Shot (FLASH) sequence was modified with additional off-resonant heating pulses. With an accelerated imaging method and a sliding-window technique, every 7.6 s a new temperature map could be generated with a spatial in-plane resolution of 2 mm. The temperature deviation from calculated temperature values to reference fluoroptic probe was found to be smaller than 1 K.

  5. Comparison of RF heating operators in Monte-Carlo calculations of quasi-linear ICH

    NASA Astrophysics Data System (ADS)

    Green, D. L.; Berry, L. A.; Jaeger, E. F.; RF-SciDAC Collaboration

    2011-10-01

    Experimental observations of ICH modification of the fast-ion distribution in Tokamak plasmas have previously been examined with self-consistent quasi-linear simulation (e.g., fast-ion D- alpha results on DIII-D and NSTX and the compact neutral particle analyzer on Alcator C-Mod). Discrepancies between zero-ion-orbit width simulation and observation have prompted the development of several finite-ion-orbit width codes, e.g., CQL3D- FOW (finite difference) and sMC (particle). Here we focus on the RF heating operator in Monte-Carlo particle codes. We compare results using the standard Stix operator which assumes a single RF wave-number, with an operator that contains the full wave- number spectrum calculated as part of the AORSA code. Scenarios where up-shift in the parallel wave-number is significant (NSTX), and not significant (C-Mod) are examined. Both operators are implemented in the GPGPU update to the sMC code. Work supported under US DOE contract DE-AC05-00OR22725.

  6. Self-heating study of bulk acoustic wave resonators under high RF power.

    PubMed

    Ivira, Brice; Fillit, René-Yves; Ndagijimana, Fabien; Benech, Philippe; Parat, Guy; Ancey, Pascal

    2008-01-01

    The present work first provides an experimental technique to study self-heating of bulk acoustic wave (BAW) resonators under high RF power in the gigahertz range. This study is specially focused on film bulk acoustic wave resonators and solidly mounted resonators processed onto silicon wafers and designed for wireless systems. Precisely, the reflection coefficient of a one-port device is measured while up to several watts are applied and power leads to electrical drifts of impedances. In the following, we describe how absorbed power can be determined from the incident one in real time. Therefore, an infrared camera held over the radio frequency micro electromechanical system (RF-MEMS) surface with an exceptional spatial resolution reaching up to 2 microm/pixels gives accurate temperature mapping of resonators after emissivity correction. From theoretical point of view, accurate three-dimensional (3-D) structures for finite-element modeling analyses are carried out to know the best materials and architectures to use for enhancing power handling. In both experimental and theoretical investigations, comparison is made between film bulk acoustic wave resonators and solidly mounted resonators. Thus, the trend in term of material, architecture, and size of device for power application such as in transmission path of a transceiver is clearly identified. PMID:18334320

  7. Novel magnetic core materials impact modelling and analysis for minimization of RF heating loss

    NASA Astrophysics Data System (ADS)

    Ghosh, Bablu Kumar; Mohamad, Khairul Anuar; Saad, Ismail

    2016-02-01

    The eddy current that exists in RF transformer/inductor leads to generation of noise/heat in the circuit and ultimately reduces efficiency in RF system. Eddy current is generated in the magnetic core of the inductor/transformer largely determine the power loss for power transferring process. The losses for high-frequency magnetic components are complicated due to both the eddy current variation in magnetic core and copper windings reactance variation with frequency. Core materials permeability and permittivity are also related to variation of such losses those linked to the operating frequency. This paper will discuss mainly the selection of novel magnetic core materials for minimization of eddy power loss by using the approach of empirical equation and impedance plane simulation software TEDDY V1.2. By varying the operating frequency from 100 kHz to 1GHz and magnetic flux density from 0 to 2 Tesla, the eddy power loss is evaluated in our study. The Nano crystalline core material is found to be the best core material due to its low eddy power loss at low conductivity for optimum band of frequency application.

  8. Observations of Anisotropic Ion Temperature in the NSTX Edge during RF Heating

    SciTech Connect

    T.M. Biewer; R.E. Bell; P.M. Ryan; J.R. Wilson

    2004-06-28

    A new spectroscopic diagnostic with both toroidal and poloidal views has been implemented in the edge of the National Spherical Torus Experiment (NSTX). This edge rotation diagnostic (ERD) was designed to measure the velocity and temperature of ions. The intersection of the diagnostic sightlines with the intrinsic emission shell provides the localization of the measurement. There are 7 toroidally directed views and 6 poloidally directed views of the outboard plasma edge. The poloidal view is {approx}20 cm (toroidally) from the RF antenna, and the toroidal view is {approx}2 m away. The sightlines are nearly tangent to the flux surfaces. The C{sup 2+} triplet near 4651 {angstrom} and the He{sup +} line at 4685 {angstrom} are measured. In the results presented here, helium is the bulk, ''working'' ion of the discharge. The NSTX is a large spherical tokamak with a major radius of 0.85 m and a minor radius of 0.65 m. The outer walls and center-stack are lined with protective carbon tiles. Pulse lengths for these NSTX discharges are {approx} 600 ms, with an on-axis toroidal magnetic field of {approx} 0.3 T. The plasma current is 500 kA. The on-axis electron temperature and density are {le} 2 keV and {approx} 2 x 10{sup 19} m{sup -3}, respectively with {le} 4.3 MW of High Harmonic Fast Wave (HHFW) Radio Frequency (RF) auxiliary heating.

  9. Self-heating study of bulk acoustic wave resonators under high RF power.

    PubMed

    Ivira, Brice; Fillit, René-Yves; Ndagijimana, Fabien; Benech, Philippe; Parat, Guy; Ancey, Pascal

    2008-01-01

    The present work first provides an experimental technique to study self-heating of bulk acoustic wave (BAW) resonators under high RF power in the gigahertz range. This study is specially focused on film bulk acoustic wave resonators and solidly mounted resonators processed onto silicon wafers and designed for wireless systems. Precisely, the reflection coefficient of a one-port device is measured while up to several watts are applied and power leads to electrical drifts of impedances. In the following, we describe how absorbed power can be determined from the incident one in real time. Therefore, an infrared camera held over the radio frequency micro electromechanical system (RF-MEMS) surface with an exceptional spatial resolution reaching up to 2 microm/pixels gives accurate temperature mapping of resonators after emissivity correction. From theoretical point of view, accurate three-dimensional (3-D) structures for finite-element modeling analyses are carried out to know the best materials and architectures to use for enhancing power handling. In both experimental and theoretical investigations, comparison is made between film bulk acoustic wave resonators and solidly mounted resonators. Thus, the trend in term of material, architecture, and size of device for power application such as in transmission path of a transceiver is clearly identified.

  10. Experimental study of rf pulsed heating on oxygen free electronic copper

    NASA Astrophysics Data System (ADS)

    Pritzkau, David P.; Siemann, Robert H.

    2002-11-01

    When the thermal stresses induced by rf pulsed heating are larger than the elastic limit, microcracks and surface roughening will occur due to cyclic fatigue. Therefore, pulsed heating limits the maximum surface magnetic field and through it the maximum achievable accelerating gradient. An experiment using circularly cylindrical cavities operating in the TE011 mode at a resonant frequency of 11.424GHz was designed to study pulsed heating on oxygen free electronic (OFE) copper. An X-band klystron delivered up to 10MW to the cavities in 1.5 μs pulses at 60Hz repetition rate. One run was executed at a temperature rise of 120K for 56×106 pulses. Cracks at grain boundaries, slip bands, and cracks associated with these slip bands were observed. The second run consisted of 86×106 pulses with a temperature rise of 82K, and cracks at grain boundaries and slip bands were seen. Additional information can be derived from the power-coupling iris, and we conclude that a pulsed temperature rise of 250K for several million pulses leads to destruction of copper. These results can be applied to any mode of any OFE copper cavity.

  11. A heterogeneous human tissue mimicking phantom for RF heating and MRI thermal monitoring verification

    NASA Astrophysics Data System (ADS)

    Yuan, Yu; Wyatt, Cory; Maccarini, Paolo; Stauffer, Paul; Craciunescu, Oana; MacFall, James; Dewhirst, Mark; Das, Shiva K.

    2012-04-01

    This paper describes a heterogeneous phantom that mimics a human thigh with a deep-seated tumor, for the purpose of studying the performance of radiofrequency (RF) heating equipment and non-invasive temperature monitoring with magnetic resonance imaging (MRI). The heterogeneous cylindrical phantom was constructed with an outer fat layer surrounding an inner core of phantom material mimicking muscle, tumor and marrow-filled bone. The component materials were formulated to have dielectric and thermal properties similar to human tissues. The dielectric properties of the tissue mimicking phantom materials were measured with a microwave vector network analyzer and impedance probe over the frequency range of 80-500 MHz and at temperatures of 24, 37 and 45 °C. The specific heat values of the component materials were measured using a differential scanning calorimeter over the temperature range of 15-55 °C. The thermal conductivity value was obtained from fitting the curves obtained from one-dimensional heat transfer measurement. The phantom was used to verify the operation of a cylindrical four-antenna annular phased array extremity applicator (140 MHz) by examining the proton resonance frequency shift (PRFS) thermal imaging patterns for various magnitude/phase settings (including settings to focus heating in tumors). For muscle and tumor materials, MRI was also used to measure T1/T2* values (1.5 T) and to obtain the slope of the PRFS phase change versus temperature change curve. The dielectric and thermal properties of the phantom materials were in close agreement to well-accepted published results for human tissues. The phantom was able to successfully demonstrate satisfactory operation of the tested heating equipment. The MRI-measured thermal distributions matched the expected patterns for various magnitude/phase settings of the applicator, allowing the phantom to be used as a quality assurance tool. Importantly, the material formulations for the various tissue types

  12. An overview of the VASIMR engine: High power space propulsion with RF plasma generation and heating

    NASA Astrophysics Data System (ADS)

    Díaz, F. R. Chang

    2001-10-01

    The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is a high power, radio frequency-driven magnetoplasma rocket, capable of exhaust modulation at constant power. While the plasma is produced by a helicon discharge, the bulk of the energy is added in a separate downstream stage by ion cyclotron resonance heating (ICRH). Axial momentum is obtained by the adiabatic expansion of the plasma in a magnetic nozzle. Exhaust variation in the VASIMR is primarily achieved by the selective partitioning of the RF power to the helicon and ICRH systems, with the proper adjustment of the propellant flow. However, other complementary techniques are also being studied. Operational and performance considerations favor the light gases. The physics and engineering of this device have been under study since the late 1970s. A NASA-led, research effort, involving several terms in the United States, continues to explore the scientific and technological foundations of this concept. The research involves theory, experiment, engineering design, mission analysis, and technology development. Experimentally, high density, stable plasma discharges have been generated in Helium, Hydrogen and Deuterium, as well as mixtures of these gases. Key issues involve the optimization of the helicon discharge for high-density operation and the efficient coupling of ICRH to the plasma, prior to acceleration by the magnetic nozzle. Theoretically, the dynamics of the magnetized plasma are being studied from kinetic and fluid perspectives. Plasma acceleration by the magnetic nozzle and subsequent detachment has been demonstrated in numerical simulations. These results are presently undergoing experimental verification. A brisk technology development effort for space-qualified, compact, solid-state RF equipment, and high temperature superconducting magnets is under way in support of this project. A conceptual point design for an early space demonstrator on the International Space Station has been defined

  13. A heterogeneous human tissue mimicking phantom for RF heating and MRI thermal monitoring verification

    PubMed Central

    Yuan, Yu; Wyatt, Cory; Maccarini, Paolo; Stauffer, Paul; Craciunescu, Oana; MacFall, James; Dewhirst, Mark; Das, Shiva K.

    2013-01-01

    This paper describes a heterogeneous phantom that mimics a human thigh with a deep seated tumor, for the purpose of studying the performance of radiofrequency (RF) heating equipment and non-invasive temperature monitoring with magnetic resonance imaging (MRI). The heterogeneous cylindrical phantom was constructed with an outer fat layer surrounding an inner core of phantom material mimicking muscle, tumor and marrow-filled bone. The component materials were formulated to have dielectric and thermal properties similar to human tissues. The dielectric properties of the tissue-mimicking phantom materials were measured with a microwave vector network analyzer and impedance probe over the frequency range of 80 – 500 MHz and at temperatures of 24°C, 37°C, and 45°C. The specific heat values of the component materials were measured using a differential scanning calorimeter over the temperature range of 15 – 55°C. The thermal conductivity value was obtained from fitting the curves obtained from one-dimensional heat transfer measurement. The phantom was used to verify the operation of a cylindrical 4-antenna annular phased array extremity applicator (140 MHz), by examining the proton resonance frequency shift (PRFS) thermal imaging patterns for various magnitude/phase settings (including settings to focus heating in tumor). For muscle and tumor materials, MR imaging was also used to measure T1/T2* values (1.5 Tesla) and to obtain the slope of the PRFS phase change vs. temperature change curve. The dielectric and thermal properties of the phantom materials were in close agreement to well-accepted published results for human tissues. The phantom was able to successfully demonstrate satisfactory operation of the tested heating equipment. The MRI-measured thermal distributions matched the expected patterns for various magnitude/phase settings of the applicator, allowing the phantom to be used as a quality assurance tool. Importantly, the material formulations for the

  14. RF Sources for the ITER Ion Cyclotron Heating and Current Drive System

    SciTech Connect

    Hosea, J.; Brunkhorst, C.; Fredd, E.; Goulding, R. H.; Goulding, R. H.; Greenough, N.; Kung, C.; Rasmussen, D. A.; Swain, D. W.; Wilson, J. R.

    2005-10-04

    The RF source requirements for the ITER ion cyclotron (IC) heating and current drive system are very challenging ? 20 MW CW power into an antenna load with a VSWR of up to 2 over the frequency range of 35-65 MHz. For the two present antenna designs under consideration, 8 sources providing 2.5 MW each are to be employed. For these sources, the outputs of two final power amplifiers (FPAs), using the high power CPI 4CM2500KG tube, are combined with a 180? hybrid combiner to easily meet the ITER IC source requirements ? 2.5 MW is supplied at a VSWR of 2 at ? 70% of the maximum tube power available in class B operation. The cylindrical cavity configuration for the FPAs is quite compact so that the 8 combined sources fit into the space allocated at the ITER site with room to spare. The source configuration is described in detail and its projected operating power curves are presented. Although the CPI tube has been shown to be stable under high power operating conditions on many facilities, a test of the combined FPA source arrangement is in preparation using existing high power 30 MHz amplifiers to assure that this configuration can be made robustly stable for all phases at a VSWR up to 2. The possibility of using 12 sources to feed a suitably modified antenna design is also discussed in the context of providing flexibility for specifying the final IC antenna design.

  15. High temperature metal purification using a compact portable rf heating and levitation system on the wake shield

    NASA Technical Reports Server (NTRS)

    Hahs, C. A.

    1990-01-01

    The Wake Shield Facility (WSF) can provide an ideal vacuum environment for the purification of high temperature metals in space. The Modular Electromagnetic Levitator (MEL), will provide the opportunity to study undercooling of metals in space and allow to determine material properties in space. The battery powered rf levitation and heating system developed for the MEL demonstrated efficiency of 36 percent. This system is being considered to purify metals at temperatures below 3000 C.

  16. Effect of deuteron temperature on iron forbidden line intensities in rf-heated tokamak plasmas

    SciTech Connect

    Sato, K.; Suckewer, S.; Wouters, A.

    1987-05-01

    Two line ratios, the forbidden line at 845.5 A (2s/sup 2/2p /sup 2/P/sub 1/2/ - 2s/sup 2/2p /sup 2/P/sub 3/2/) to the allowed line at 135.7 A (2s/sup 2/2p /sup 2/P/sub 1/2/ - 2s2p/sup 2/ /sup 2/D/sub 3/2/) in Fe XXII and the forbidden line at 592.1 A (2s/sup 2/2p/sup 4/ /sup 3/P/sub 2/ - 2s/sup 2/2p/sup 4/ /sup 1/D/sub 2/) to the forbidden line at 1118.2 A (2s/sup 2/2p/sup 4/ /sup 3/P/sub 2/ - 2s/sup 2/2p/sup 4/ /sup 3/P/sub 1/) in Fe XIX, have been measured as the ion temperature-sensitive line ratios during rf heating in the Princeton Large Torus. The results indicate that deuteron collisions in plasmas of high deuteron temperature have a noticeable effect on the intensity of the forbidden lines. Measured relative intensities are compared with values from level population calculations, which include deuteron collisional excitation between the levels of the ground configuration. The agreement between the observed and calculated ratios is within 30%. A method for deuteron (or proton) temperature measurement in tokamak plasmas is discussed. 37 refs.

  17. Low-frequency RF hyperthermia: IV--A 27 MHz hybrid applicator for localized deep tumor heating.

    PubMed

    Franconi, C; Raganella, L; Tiberio, C A

    1991-03-01

    A 27 MHz dual-device applicator of novel design, which is aimed to heat noninvasively with improved safety tumor masses at depth, is proposed. A substantially localized temperature gain is obtained by superimposing two delocalized low RF frequency and phase-coherent current distributions, which are launched to constructively interfere over a limited region emcompassing the tumor volume. An hybrid applicator (HA) has been developed, integrated one capacitive and one inductive heating device, and has been assessed on a 20 cm diameter cylindrical fat-muscle phantom. The interference pattern is characterized by a deep broad SAR maximum and by the disappearance of the central null SAR value typical of single inductive devices. An 80% SAR useful therapeutic volume (UTV) of a near-cylindrical shape of about 800 cm3 is obtained with a penetration of 6-8 cm for the phantom surface, with a noncritical axial length of approximately 21 cm. The UTV may be somehow controlled in size and penetration. These results are obtained with the tissue-like medium surrounding the UTV heated uniformly and safely to a temperature pedestal below the therapeutic temperature with about half RF power values to each of the heating devices.

  18. Self-generated stochastic heating in an rf discharge. Annual progress report, May 15, 1991--May 14, 1992

    SciTech Connect

    Lichtenberg, A.

    1992-08-01

    We have studied the nonlinear dynamics of stochastic heating arising from the reflection of electrons from moving sheaths as an underlying mechanism for electron power deposition in r.f. discharges. We examined the dynamics of the electron collision with the sheaths in the regime in which the sheath motion is small compared to the average electron velocity to de rive a mop that describes the electron motion. We have shown that for high frequency, ({omega}/2{pi}{approx_gt}50MHz), the electrons will strike the moving wall with random phase. At low pressures this stochasticity is an intrinsic property of the dynamics. The stochastic electron heating leads to a power law electron distribution. The stochastic heating was determined in both the slow sheath and fast sheath velocity regimes assuming an incident Maxwellian distribution.

  19. Evaluation of the RF heating of a generic deep brain stimulator exposed in 1.5 T magnetic resonance scanners.

    PubMed

    Cabot, Eugenia; Lloyd, Tom; Christ, Andreas; Kainz, Wolfgang; Douglas, Mark; Stenzel, Gregg; Wedan, Steve; Kuster, Niels

    2013-02-01

    The radio frequency (RF) electromagnetic field of magnetic resonance (MR) scanners can result in significant tissue heating due to the RF coupling with the conducting parts of medical implants. The objective of this article is to evaluate the advantages and shortcomings of a new four-tier approach based on a combined numerical and experimental procedure, designed to demonstrate safety of implants during MR scans. To the authors' best knowledge, this is the first study analyzing this technique. The evaluation is performed for 1.5 T MR scanners using a generic model of a deep brain stimulator (DBS) with a straight lead and a helical lead. The results show that the approach is technically feasible and provides sound and conservative information about the potential heating of implants. We demonstrate that (1) applying optimized tools results in reasonable uncertainties for the overall evaluation; (2) each tier reduces the overestimation by several dB at the cost of more demanding evaluation steps; (3) the implant with the straight lead would cause local temperature increases larger than 18 °C at the RF exposure limit for the normal operating mode; (4) Tier 3 is not sufficient for the helical implant; and (5) Tier 4 might be too demanding to be performed for complex implants. We conclude with a suggestion for a procedure that follows the same concept but is between Tier 3 and 4. In addition, the evaluation of Tier 3 has shown consistency with current scan practice, namely, the resulting heat at the lead tip is less than 3.5 °C for the straight lead and 0.7 °C for the helix lead for scans at the current applied MR scan restrictions for deep brain stimulation at a head average SAR of 0.1 W/kg.

  20. Application of the Finite Orbit Width Version of the CQL3D Code to NBI +RF Heating of NSTX Plasma

    NASA Astrophysics Data System (ADS)

    Petrov, Yu. V.; Harvey, R. W.

    2015-11-01

    The CQL3D bounce-averaged Fokker-Planck (FP) code has been upgraded to include Finite-Orbit-Width (FOW) effects. The calculations can be done either with a fast Hybrid-FOW option or with a slower but neoclassically complete full-FOW option. The banana regime neoclassical radial transport appears naturally in the full-FOW version by averaging the local collision coefficients along guiding center orbits, with a proper transformation matrix from local (R, Z) coordinates to the midplane computational coordinates, where the FP equation is solved. In a similar way, the local quasilinear rf diffusion terms give rise to additional radial transport of orbits. The full-FOW version is applied to simulation of ion heating in NSTX plasma. It is demonstrated that it can describe the physics of transport phenomena in plasma with auxiliary heating, in particular, the enhancement of the radial transport of ions by RF heating and the occurrence of the bootstrap current. Because of the bounce-averaging on the FPE, the results are obtained in a relatively short computational time. A typical full-FOW run time is 30 min using 140 MPI cores. Due to an implicit solver, calculations with a large time step (tested up to dt = 0.5 sec) remain stable. Supported by USDOE grants SC0006614, ER54744, and ER44649.

  1. High-temperature metal purification using a compact, portable rf heating and levitation system on the wake shield

    NASA Technical Reports Server (NTRS)

    Hahs, C. A.

    1990-01-01

    The potential use of a compact, battery-operated rf levitator and heating system to purify high-temperature melting materials in space is described. The wake shield now being fabricated for the Space Vacuum Epitaxy Center will provide an Ultra-high vacuum (10(exp -14) Torr hydrogen, 10(exp -14) Torr helium, 10(exp -30) Torr oxygen). The use of the wake shield to purify Nb, Ti, W, Ir, and other metals to a purity level not achievable on earth is described.

  2. Compact rf heating and levitation systems for the NASA modular electromagnetic levitator

    NASA Technical Reports Server (NTRS)

    Fox, R. J.

    1990-01-01

    The levitator demonstrates levitation of a 5 mm diam aluminum sphere at 1 G using a small, compact rf levitator operating from a small 12-V battery. This system is designed to levitate and melt niobium in space; however, the small battery unit limits the power for melting operations.

  3. Integrated design and analysis of RF heating and current drive systems

    NASA Astrophysics Data System (ADS)

    Ryan, P. M.; Carter, M. D.; Goulding, R. H.; Batchelor, D. B.; Jaeger, E. F.; Stallings, D. C.; Wang, C. Y.; Baity, F. W.; Bell, G. L.; Bigelow, T. S.; England, A. C.; Hanson, G. R.; Haste, G. R.; Hoffman, D. J.; Murakami, M.; Rasmussen, D. A.; Wilgen, J. B.; Rogers, J. H.; Majeski, R.; Schilling, G.; Wilson, J. R.; Bhatnagar, V.; Bures, M.; Kaye, A.; Start, D.; Wade, T.; Ho, Y. L.; Kruger, W.

    1996-02-01

    The design, analysis, and performance evaluation of rf power systems ultimately requires accurate modeling of a chain of subsystems starting with the rf transmitter and ending with the power absorption in the plasma. A collection of computer codes is used at ORNL to calculate the plasma loading and wave spectrum for a three-dimensional rf antenna, the transmission/reflection properties of the Faraday shield and its effect on the electrical characteristics and phase velocity of the antenna, the internal coupling among antenna array components and the incorporation of the antenna array into a transmission line model of the phase control, tuning, matching, and power distribution system. Some codes and techniques are more suited for the rapid evaluation of system design progressions, while others are more applicable to the detailed analysis of final designs or existing hardware. The interaction of codes and the accuracy of calculations will be illustrated by the process of determining the plasma loading as a function of phasing and density profiles for the TFTR ICRH antennas and comparing the results to measurements. An example of modeling a complex antenna geometry will be the comparison of calculations with the measured electrical response of a four-strap mockup of the JET A2 antenna array which was loaned to ORNL by the JET ICRH team.

  4. Report on Solar Water Heating Quantitative Survey

    SciTech Connect

    Focus Marketing Services

    1999-05-06

    This report details the results of a quantitative research study undertaken to better understand the marketplace for solar water-heating systems from the perspective of home builders, architects, and home buyers.

  5. Maine State Planning Office, 1990--1991 heating season home heating fuels price survey. Final report

    SciTech Connect

    Not Available

    1991-12-31

    The 1990--1991 heating season was the first time in Maine that the Home Heating Fuels Survey was conducted for the United States Department of Energy by the Maine State Planning Office. This season also marked the first time that dealers were surveyed for a price for propane. Under a late agreement, the State of Maine was picked up by the regional survey of the Energy Information Agency in the beginning of October. This accounted for the weekly survey of the traditional participants in the State`s Home Heating Fuels Price Survey being supplemented by biweekly DOE surveys of separate survey samples of oil and propane dealers. The SPO sample identifies 36 dealers in the State of Maine, while the DOE sample was constructed around 22 oil dealers in Maine and New Hampshire and 29 propane dealers in Maine.

  6. Maine State Planning Office, 1990--1991 heating season home heating fuels price survey

    SciTech Connect

    Not Available

    1991-01-01

    The 1990--1991 heating season was the first time in Maine that the Home Heating Fuels Survey was conducted for the United States Department of Energy by the Maine State Planning Office. This season also marked the first time that dealers were surveyed for a price for propane. Under a late agreement, the State of Maine was picked up by the regional survey of the Energy Information Agency in the beginning of October. This accounted for the weekly survey of the traditional participants in the State's Home Heating Fuels Price Survey being supplemented by biweekly DOE surveys of separate survey samples of oil and propane dealers. The SPO sample identifies 36 dealers in the State of Maine, while the DOE sample was constructed around 22 oil dealers in Maine and New Hampshire and 29 propane dealers in Maine.

  7. Electrical residential water heating: A consumption and conservation survey

    SciTech Connect

    Pontikakis, N.; Ruth, D.W.

    1994-12-31

    An extensive review of published material on electrical residential water heating was performed, and comments are presented concerning critical issues of water heating. First, the phenomenon of Legionella pneumophila bacteria is studied. Second, electrical energy consumption is reviewed. Finally, the energy savings of improved technological devices are considered. The objective of this survey is to provide an organized report on the aforementioned aspects of electrical water heating in residential homes, thus forming a basis for conducting future research.

  8. An alternative estimation of the RF-enhanced plasma temperature during SPEAR artificial heating experiments: Early results

    NASA Astrophysics Data System (ADS)

    Vickers, H.; Baddeley, L.

    2011-11-01

    RF heating of the F region plasma at high latitudes has long been known to produce electron temperature increases that can vary from tens to hundreds of percent above the background, unperturbed level. In contrast, artificial ionospheric modification experiments conducted using the Space Plasma Exploration by Active Radar (SPEAR) heating facility on Svalbard have often failed to produce obvious enhancements in the electron temperatures when measured using the European Incoherent Scatter Svalbard radar (ESR), colocated with the heater. Contamination of the ESR ion line spectra by the zero-frequency purely growing mode (PGM) feature is known to persist at varying amplitudes throughout SPEAR heating, and such spectral features can lead to significant temperature underestimations when the incoherent scatter spectra are analyzed using conventional methods. In this study, we present the first results of applying a recently developed technique to correct the PGM-contaminated spectra to SPEAR-enhanced ESR spectra and derive an alternative estimate of the SPEAR-heated electron temperature. We discuss how the effectiveness of the spectrum corrections can be affected by the data variance, estimated over the integration period. The subsequent electron temperatures, inferred from corrected spectra, range from a few tens to a few hundred Kelvin above the average background temperature. These temperatures are found to be in reasonable agreement with the theoretical “enhanced” temperature, calculated for the peak of the stationary temperature perturbation profile, when realistic absorption effects are accounted for.

  9. Impedance matched, high-power, rf antenna for ion cyclotron resonance heating of a plasma

    DOEpatents

    Baity, Jr., Frederick W.; Hoffman, Daniel J.; Owens, Thomas L.

    1988-01-01

    A resonant double loop radio frequency (rf) antenna for radiating high-power rf energy into a magnetically confined plasma. An inductive element in the form of a large current strap, forming the radiating element, is connected between two variable capacitors to form a resonant circuit. A real input impedance results from tapping into the resonant circuit along the inductive element, generally near the midpoint thereof. The impedance can be matched to the source impedance by adjusting the separate capacitors for a given tap arrangement or by keeping the two capacitances fixed and adjustng the tap position. This results in a substantial reduction in the voltage and current in the transmission system to the antenna compared to unmatched antennas. Because the complete circuit loop consisting of the two capacitors and the inductive element is resonant, current flows in the same direction along the entire length of the radiating element and is approximately equal in each branch of the circuit. Unidirectional current flow permits excitation of low order poloidal modes which penetrate more deeply into the plasma.

  10. A Survey of Pressure Vessel Code Compliance for Superconducting RF Cryomodules

    SciTech Connect

    Peterson, Thomas; Klebaner, Arkadiy; Nicol, Tom; Theilacker, Jay; Hayano, Hitoshi; Kako, Eiji; Nakai, Hirotaka; Yamamoto, Akira; Jensch, Kay; Matheisen, Axel; Mammosser, John; /Jefferson Lab

    2011-06-07

    Superconducting radio frequency (SRF) cavities made from niobium and cooled with liquid helium are becoming key components of many particle accelerators. The helium vessels surrounding the RF cavities, portions of the niobium cavities themselves, and also possibly the vacuum vessels containing these assemblies, generally fall under the scope of local and national pressure vessel codes. In the U.S., Department of Energy rules require national laboratories to follow national consensus pressure vessel standards or to show ''a level of safety greater than or equal to'' that of the applicable standard. Thus, while used for its superconducting properties, niobium ends up being treated as a low-temperature pressure vessel material. Niobium material is not a code listed material and therefore requires the designer to understand the mechanical properties for material used in each pressure vessel fabrication; compliance with pressure vessel codes therefore becomes a problem. This report summarizes the approaches that various institutions have taken in order to bring superconducting RF cryomodules into compliance with pressure vessel codes. In Japan, Germany, and the U.S., institutions building superconducting RF cavities integrated in helium vessels or procuring them from vendors have had to deal with pressure vessel requirements being applied to SRF vessels, including the niobium and niobium-titanium components of the vessels. While niobium is not an approved pressure vessel material, data from tests of material samples provide information to set allowable stresses. By means of procedures which include adherence to code welding procedures, maintaining material and fabrication records, and detailed analyses of peak stresses in the vessels, or treatment of the vacuum vessel as the pressure boundary, research laboratories around the world have found methods to demonstrate and document a level of safety equivalent to the applicable pressure vessel codes.

  11. Axial heating and temperature of RF-excited non-neutral plasmas in Penning-Malmberg traps

    NASA Astrophysics Data System (ADS)

    Maero, G.; Pozzoli, R.; Romé, M.; Chen, S.; Ikram, M.

    2016-09-01

    Electro-magnetostatic traps have been used for decades to provide long-term storage of charged particle samples or non-neutral plasmas. The dynamics and equilibrium states of these ideally simple systems can be strongly diverted from the usual working conditions (i.e. single-species, quiescent samples) in the presence of oppositely charged particles or external electric field perturbations. Both these conditions occur when the plasma is generated by means of a radio-frequency (RF) excitation continuously applied on a trap electrode. The application of RF drives of some volts over periods larger than typical collisional time scales leads to residual-gas ionization and to the accumulation of an electron plasma, a process that has previously been exploited as an alternative to thermionic or photoemission electron sources. The analysis of the axial energy distribution shows a deviation of the continuously excited final state from maxwellianity dependent on the radial position and the subsequent relaxation to equilibrium after the interruption of the drive. Systematic measurements also indicate the high sensitivity to the residual gas pressure of both the total confined charge and of the attainable densities and plasma profiles. The results are compared to the information obtained from a very simple one-dimensional electron heating model and show the validity of its most basic features together with its shortcomings.

  12. RF Plasma Heating in the PFRC-2 Device: Motivation, Goals and Methods

    SciTech Connect

    Cohen, S.; Brunkhorst, C.; Glasser, A.; Landsman, A.; Welch, D.

    2011-12-23

    The motivation for using radio frequency, odd-parity rotating magnetic fields for heating field-reversed-configuration (FRC) plasmas is explained. Calculations are presented of the expected electron and ion temperatures in the PFRC-2 device, currently under construction.

  13. Improved reliability of repetitive RF interstitial heating in combination with brachytherapy: the effective use of water.

    PubMed

    Kasai, T; Kato, H; Uchida, N; Sugihara, M; Sugimura, K

    2001-01-01

    Interstitial heating and brachytherapy are often combined in the treatment of cancer. In such instances, a needle-type internal electrode is inserted into the RALS (remotely controlled afterloading system) catheter instead of a radioactive source. A problem with this approach, however, is that the temperature distribution pattern generated by the inserted electrode varies at any given target region in each heating treatment, which makes it difficult to accurately replicate the heating treatment protocol. This variation is suspected to be caused by non-uniformity in the small gap between the internal electrode and the inner surface of the surrounding catheter, causing electric currents to flow between the electrode and the heating material, which differs from procedure to procedure. To solve this problem, the gap was filled with water of high permittivity, and the temperature distribution was investigated using phantoms. With this method, a stable and reproducible temperature rise distribution was obtained in the phantom experiment.

  14. A temperature-jump NMR probe setup using rf heating optimized for the analysis of temperature-induced biomacromolecular kinetic processes

    NASA Astrophysics Data System (ADS)

    Rinnenthal, Jörg; Wagner, Dominic; Marquardsen, Thorsten; Krahn, Alexander; Engelke, Frank; Schwalbe, Harald

    2015-02-01

    A novel temperature jump (T-jump) probe operational at B0 fields of 600 MHz (14.1 Tesla) with an integrated cage radio-frequency (rf) coil for rapid (<1 s) heating in high-resolution (HR) liquid-state NMR-spectroscopy is presented and its performance investigated. The probe consists of an inner 2.5 mm "heating coil" designed for generating rf-electric fields of 190-220 MHz across a lossy dielectric sample and an outer two coil assembly for 1H-, 2H- and 15N-nuclei. High B0 field homogeneities (0.7 Hz at 600 MHz) are combined with high heating rates (20-25 K/s) and only small temperature gradients (<±1.5 K, 3 s after 20 K T-jump). The heating coil is under control of a high power rf-amplifier within the NMR console and can therefore easily be accessed by the pulse programmer. Furthermore, implementation of a real-time setup including synchronization of the NMR spectrometer's air flow heater with the rf-heater used to maintain the temperature of the sample is described. Finally, the applicability of the real-time T-jump setup for the investigation of biomolecular kinetic processes in the second-to-minute timescale is demonstrated for samples of a model 14mer DNA hairpin and a 15N-selectively labeled 40nt hsp17-RNA thermometer.

  15. Using a Cold Radiometer to Measure Heat Loads and Survey Heat Leaks

    NASA Technical Reports Server (NTRS)

    Dipirro, M.; Tuttle, J.; Hait, T.; Shirron, P.

    2014-01-01

    We have developed an inexpensive cold radiometer for use in thermal/vacuum chambers to measure heat loads, characterize emissivity and specularity of surfaces and to survey areas to evaluate stray heat loads. We report here the results of two such tests for the James Webb Space Telescope to measure heat loads and effective emissivities of 2 major pieces of optical ground support equipment that will be used in upcoming thermal vacuum testing of the Telescope.

  16. Using a cold radiometer to measure heat loads and survey heat leaks

    NASA Astrophysics Data System (ADS)

    DiPirro, M.; Tuttle, J.; Hait, T.; Shirron, P.

    2014-01-01

    We have developed an inexpensive cold radiometer for use in thermal/vacuum chambers to measure heat loads, characterize emissivity and specularity of surfaces and to survey areas to evaluate stray heat loads. We report here the results of two such tests for the James Webb Space Telescope to measure heat loads and effective emissivities of 2 major pieces of optical ground support equipment that will be used in upcoming thermal vacuum testing of the Telescope.

  17. Using a Cold Radiometer to Measure Heat Loads and Survey Heat Leaks

    NASA Technical Reports Server (NTRS)

    DiPirro, M.; Tuttle, J.; Hait, T.; Shirron, P.

    2013-01-01

    We have developed an inexpensive cold radiometer for use in thermal/vacuum chambers to measure heat loads, characterize emissivity and specularity of surfaces and to survey areas to evaluate stray heat loads. We report here the results of two such tests for the James Webb Space Telescope to measure heat loads and effective emissivities of2 major pieces of optical ground support equipment that will be used in upcoming thermal vacuum testing of the Telescope.

  18. Using a cold radiometer to measure heat loads and survey heat leaks

    SciTech Connect

    DiPirro, M.; Tuttle, J.; Hait, T.; Shirron, P.

    2014-01-29

    We have developed an inexpensive cold radiometer for use in thermal/vacuum chambers to measure heat loads, characterize emissivity and specularity of surfaces and to survey areas to evaluate stray heat loads. We report here the results of two such tests for the James Webb Space Telescope to measure heat loads and effective emissivities of 2 major pieces of optical ground support equipment that will be used in upcoming thermal vacuum testing of the Telescope.

  19. Discussion based on numerical and experimental studies on heating characteristics of an RF rectangular resonant cavity applicator for hyperthermia targeting deep-seated tumors.

    PubMed

    Tange, Yutaka; Kanai, Yasushi; Saitoh, Yoshiaki

    2007-01-01

    The heating characteristics of an RF rectangular cavity applicator for hyperthermic treatment that targets deep-seated tumors were investigated numerically and experimentally. In the numerical study, Maxwell's equations and heat transfer equations were solved for a dielectric phantom with and without blood flow. Conductive caps attached to the dielectric phantom to shield the non-tumor regions. The experimental study showed the validity and possibility of heating deep-seated tumors. Thus, the rectangular resonant cavity applicator with an L-type antenna can heat deep-seated tumors.

  20. Lower hybrid rf heating experiments in the MIT Alcator A, C and Versator II tokamaks

    SciTech Connect

    Porkolab, M.; Schuss, J.; Takase, Y.; Chen, K.I.; Knowlton, S.; Luckhardt, S.; McDermott, S.

    1980-01-01

    Experimental results on lower hybrid heating in the Alcator A and the Versator II tokamaks with power levels up to 90 kW are presented. In Alcator A a double waveguide grill, and in Versator II a 4 waveguide grill with arbitrary phasing are used. Also, a 6 waveguide grill experiment in Versator II is described which launches a travelling wave aimed at driving toroidal currents. The forthcoming lower hybrid heating experiment in Alcator C, utilizing four 4 x 4 waveguide arrays with power levels up to 4 MW, is also described.

  1. Numerical simulation of EC-heating at the tangent injection of RF radiation in tokamak

    NASA Astrophysics Data System (ADS)

    Balakina, M. A.; Smolyakova, O. B.; Tokman, M. D.

    2003-02-01

    The scheme of the tangent injection of microwave radiation providing the minimal width of magnetic surfaces layer being heated is under analyses on the basis of geometrical optical subrelativistic code. Numerical simulation demonstrates that the localization of the energy-release zone achievable at the tangent injection satisfies completely possible requirements of the experiment on tearing-mode stabilization in plant with ITER parameters.

  2. Consideration of the effects of intense tissue heating on the RF electromagnetic fields during MRI: simulations for MRgFUS in the hip.

    PubMed

    Xin, Sherman Xuegang; Gu, Shiyong; Carluccio, Giuseppe; Collins, Christopher M

    2015-01-01

    Due to the strong dependence of tissue electrical properties on temperature, it is important to consider the potential effects of intense tissue heating on the RF electromagnetic fields during MRI, as can occur in MR-guided focused ultrasound surgery. In principle, changes of the RF electromagnetic fields could affect both efficacy of RF pulses, and the MRI-induced RF heating (SAR) pattern. In this study, the equilibrium temperature distribution in a whole-body model with 2 mm resolution before and during intense tissue heating up to 60 °C at the target region was calculated. Temperature-dependent electric properties of tissues were assigned to the model to establish a temperature-dependent electromagnetic whole-body model in a 3T MRI system. The results showed maximum changes in conductivity, permittivity, [absolute value]B(1)(+)[absolute value] and SAR of about 25%, 6%, 2%, and 20%, respectively. Though the B1 field and SAR distributions are both temperature-dependent, the potential harm to patients due to higher SARs is expected to be minimal and the effects on the B1 field distribution should have minimal effect on images from basic MRI sequences.

  3. Consideration of the effects of intense tissue heating on the RF electromagnetic fields during MRI: simulations for MRgFUS in the hip

    NASA Astrophysics Data System (ADS)

    Xuegang Xin, Sherman; Gu, Shiyong; Carluccio, Giuseppe; Collins, Christopher M.

    2015-01-01

    Due to the strong dependence of tissue electrical properties on temperature, it is important to consider the potential effects of intense tissue heating on the RF electromagnetic fields during MRI, as can occur in MR-guided focused ultrasound surgery. In principle, changes of the RF electromagnetic fields could affect both efficacy of RF pulses, and the MRI-induced RF heating (SAR) pattern. In this study, the equilibrium temperature distribution in a whole-body model with 2 mm resolution before and during intense tissue heating up to 60 °C at the target region was calculated. Temperature-dependent electric properties of tissues were assigned to the model to establish a temperature-dependent electromagnetic whole-body model in a 3T MRI system. The results showed maximum changes in conductivity, permittivity, ≤ft|\\mathbf{B}1+\\right|, and SAR of about 25%, 6%, 2%, and 20%, respectively. Though the B1 field and SAR distributions are both temperature-dependent, the potential harm to patients due to higher SARs is expected to be minimal and the effects on the B1 field distribution should have minimal effect on images from basic MRI sequences.

  4. Combination radiofrequency (RF) ablation and IV liposomal heat shock protein suppression: Reduced tumor growth and increased animal endpoint survival in a small animal tumor model

    PubMed Central

    Yang, Wei; Ahmed, Muneeb; Tasawwar, Beenish; Levchenko, Tatynana; Sawant, Rupa R.; Torchilin, Vladimir; Goldberg, S. Nahum

    2012-01-01

    Background To investigate the effect of IV liposomal quercetin (a known down-regulator of heat shock proteins) alone and with liposomal doxorubicin on tumor growth and end-point survival when combined with radiofrequency (RF) tumor ablation in a rat tumor model. Methods Solitary subcutaneous R3230 mammary adenocarcinoma tumors (1.3–1.5 cm) were implanted in 48 female Fischer rats. Initially, 32 tumors (n=8, each group) were randomized into four experimental groups: (a) conventional monopolar RF alone (70°C for 5 min), (b) IV liposomal quercetin alone (1 mg/kg), (c) IV liposomal quercetin followed 24hr later with RF, and (d) no treatment. Next, 16 additional tumors were randomized into two groups (n=8, each) that received a combined RF and liposomal doxorubicin (15 min post-RF, 8 mg/kg) either with or without liposomal quercetin. Kaplan-Meier survival analysis was performed using a tumor diameter of 3.0 cm as the defined survival endpoint. Results Differences in endpoint survival and tumor doubling time among the groups were highly significant (P<0.001). Endpoint survivals were 12.5±2.2 days for the control group, 16.6±2.9 days for tumors treated with RF alone, 15.5±2.1days for tumors treated with liposomal quercetin alone, and 22.0±3.9 days with combined RF and quercetin. Additionally, combination quercetin/RF/doxorubicin therapy resulted in the longest survival (48.3±20.4 days), followed by RF/doxorubicin (29.9±3.8 days). Conclusions IV liposomal quercetin in combination with RF ablation reduces tumor growth rates and improves animal endpoint survival. Further increases in endpoint survival can be seen by adding an additional anti-tumor adjuvant agent liposomal doxorubicin. This suggests that targeting several post-ablation processes with multi-drug nanotherapies can increase overall ablation efficacy. PMID:22230341

  5. A winter survey of domestic heating among elderly patients.

    PubMed

    Morgan, R; Blair, A; King, D

    1996-02-01

    Elderly people have a greater need for domestic heating given the time they spend at home and the decline in the body thermoregulation that occurs with ageing. The use of domestic heating by 200 mentally competent newly admitted elderly in patients was evaluated by means of a questionnaire survey. Most patients (69%) were aware of the addition of value added tax (VAT) to their fuel bill and 31% said they had reduced the amount of heating they use because of this. A third of patients (29.5%) said they had difficulty keeping warm prior to this admission. The majority of patients said they could not manage to keep warm in the winter without financial hardship. In addition, 29% said they had reduced the amount spent on food in order to pay for fuel bills. This study suggests that cold may contribute to hospital admissions in elderly patients. This should have implications for government spending and taxation policy on domestic heating. PMID:8683507

  6. Electrical properties of undoped and Li-doped NiO thin films deposited by RF sputtering without intentional heating

    NASA Astrophysics Data System (ADS)

    Sugiyama, Mutsumi; Nakai, Hiroshi; Sugimoto, Gaku; Yamada, Aika; Chichibu, Shigefusa F.

    2016-08-01

    The fundamental transmittance and electrical properties of undoped and Li-doped NiO thin films deposited by conventional RF sputtering without intentional heating were evaluated. Both the transmittance and resistivity of undoped and Li-doped NiO decreased with increasing O2 fraction in the sputtering gas, f(O2) = O2/(Ar + O2). The result is attributed to the increase in the concentration of acceptors of Ni vacancies (VNi) under oxygen-rich growth conditions. In addition to VNi, Li atom on the Ni site (LiNi) likely acts as a shallow accepter, which can explain the experimental finding that the carrier concentration of Li-doped NiO was approximately three orders of magnitude higher than that of the undoped case deposited under the same f(O2). The mobility of NiO was remarkably low (around 0.1–1.0 cm2 V‑1 s‑1) and almost independent of f(O2) or the amount of doping, reflecting the large hole effective mass.

  7. Literature survey of heat transfer enhancement techniques in refrigeration applications

    SciTech Connect

    Jensen, M.K.; Shome, B.

    1994-05-01

    A survey has been performed of the technical and patent literature on enhanced heat transfer of refrigerants in pool boiling, forced convection evaporation, and condensation. Extensive bibliographies of the technical literature and patents are given. Many passive and active techniques were examined for pure refrigerants, refrigerant-oil mixtures, and refrigerant mixtures. The citations were categorized according to enhancement technique, heat transfer mode, and tube or shell side focus. The effects of the enhancement techniques relative to smooth and/or pure refrigerants were illustrated through the discussion of selected papers. Patented enhancement techniques also are discussed. Enhanced heat transfer has demonstrated significant improvements in performance in many refrigerant applications. However, refrigerant mixtures and refrigerant-oil mixtures have not been studied extensively; no research has been performed with enhanced refrigerant mixtures with oil. Most studies have been of the parametric type; there has been inadequate examination of the fundamental processes governing enhanced refrigerant heat transfer, but some modeling is being done and correlations developed. It is clear that an enhancement technique must be optimized for the refrigerant and operating condition. Fundamental processes governing the heat transfer must be examined if models for enhancement techniques are to be developed; these models could provide the method to optimize a surface. Refrigerant mixtures, with and without oil present, must be studied with enhancement devices; there is too little known to be able to estimate the effects of mixtures (particularly NARMs) with enhanced heat transfer. Other conclusions and recommendations are offered.

  8. A survey of oscillating flow in Stirling engine heat exchangers

    NASA Technical Reports Server (NTRS)

    Simon, Terrence W.; Seume, Jorge R.

    1988-01-01

    Similarity parameters for characterizing the effect of flow oscillation on wall shear stress, viscous dissipation, pressure drop and heat transfer rates are proposed. They are based on physical agruments and are derived by normalizing the governing equations. The literature on oscillating duct flows, regenerator and porous media flows is surveyed. The operating characteristics of the heat exchanger of eleven Stirling engines are discribed in terms of the similarity parameters. Previous experimental and analytical results are discussed in terms of these parameters and used to estimate the nature of the oscillating flow under engine operating conditions. The operating points for many of the modern Stirling engines are in or near the laminar to turbulent transition region. In several engines, working fluid does not pass entirely through heat exchangers during a cycle. Questions that need to be addressed by further research are identified.

  9. Study on the L-H transition power threshold with RF heating and lithium-wall coating on EAST

    NASA Astrophysics Data System (ADS)

    Chen, L.; Xu, G. S.; Nielsen, A. H.; Gao, W.; Duan, Y. M.; Liu, H. Q.; Wang, L.; Li, M. H.; Wang, M.; Zhang, X. J.; Chen, R.; Wang, H. Q.; Sun, Z.; Ding, S. Y.; Yan, N.; Liu, S. C.; Shao, L. M.; Zhang, W.; Hu, G. H.; Li, J.; Zhang, L.; Wan, B. N.; the EAST Team

    2016-05-01

    The power threshold for low (L) to high (H) confinement mode transition achieved by radio-frequency (RF) heating and lithium-wall coating is investigated experimentally on EAST for two sets of walls: an all carbon wall (C) and molybdenum chamber and a carbon divertor (Mo/C). For both sets of walls, a minimum power threshold P thr of ~0.6 MW was found when the EAST operates in a double null (DN) divertor configuration with intensive lithium-wall coating. When operating in upper single null (USN) or lower single null (LSN), the power threshold depends on the ion  ∇B drift direction. The low density dependence of the L-H power threshold, namely an increase below a minimum density, was identified in the Mo/C wall for the first time. For the C wall only the single-step L-H transition with limited injection power is observed whereas also the so-called dithering L-H transition is observed in the Mo/C wall. The dithering behaves distinctively in a USN, DN and LSN configuration, suggesting the divertor pumping capability is an important ingredient in this transition since the internal cryopump is located underneath the lower divertor. Depending on the chosen divertor configuration, the power across the separatrix P loss increases with neutral density near the lower X-point in EAST with the Mo/C wall, consistent with previous results in the C wall (Xu et al 2011 Nucl. Fusion 51 072001). These findings suggest that the edge neutral density, the ion  ∇B drift as well as the divertor pumping capability play important roles in the L-H power threshold and transition behaviour.

  10. A Study of Fe3O4 Magnetic Nanoparticle RF Heating in Gellan Gum Polymer Under Various Experimental Conditions for Potential Application in Drug Delivery

    NASA Astrophysics Data System (ADS)

    Marcus, Gabriel E.

    Magnetic nanoparticles (MNPs) have found use in a wide variety of biomedical applications including hyperthermia, imaging and drug delivery. Certain physical properties, such as the ability to generate heat in response to an alternating magnetic field, make these structures ideal for such purposes. This study's objective was to elucidate the mechanisms primarily responsible for RF MNP heating and determine how such processes affect polymer solutions that might be useful in drug delivery. 15-20 nm magnetite (Fe3O4) nanoparticles at 0.2% and 0.5% concentrations were heated with RF fields of different strengths (200 Oe, 400 Oe and 600 Oe) in water and in 0.5% gellan gum solution. Mixing and fan cooling were used in an attempt to improve accuracy of data collection. Specific absorption rate (SAR) values were determined experimentally for each combination of solvent, concentration and field strength. Theoretical calculation of SAR was performed using a model based on linear response theory. Mixing yielded greater precision in experimental determination of SAR while the effects of cooling on this parameter were negligible. Solutions with gellan gum displayed smoother heating over time but no significant changes in SAR values. This was attributed to low polymer concentration and lack of structural phase transition. The LRT model was found to be adequate for calculating SAR at low polymer concentration and was useful in identifying Neel relaxation as the dominant heating process. Heating trials with MNPs in 2% agar confirmed Neel relaxation to be primarily responsible for heat generation in the particles studied.

  11. Survey of computer programs for heat transfer analysis

    NASA Technical Reports Server (NTRS)

    Noor, A. K.

    1982-01-01

    An overview is presented of the current capabilities of thirty-eight computer programs that can be used for solution of heat transfer problems. These programs range from the large, general-purpose codes with a broad spectrum of capabilities, large user community and comprehensive user support (e.g., ANSYS, MARC, MITAS 2 MSC/NASTRAN, SESAM-69/NV-615) to the small, special purpose codes with limited user community such as ANDES, NNTB, SAHARA, SSPTA, TACO, TEPSA AND TRUMP. The capabilities of the programs surveyed are listed in tabular form followed by a summary of the major features of each program. As with any survey of computer programs, the present one has the following limitations: (1) It is useful only in the initial selection of the programs which are most suitable for a particular application. The final selection of the program to be used should, however, be based on a detailed examination of the documentation and the literature about the program; (2) Since computer software continually changes, often at a rapid rate, some means must be found for updating this survey and maintaining some degree of currency.

  12. Survey of computer programs for heat transfer analysis

    NASA Astrophysics Data System (ADS)

    Noor, A. K.

    An overview is presented of the current capabilities of thirty-eight computer programs that can be used for solution of heat transfer problems. These programs range from the large, general-purpose codes with a broad spectrum of capabilities, large user community and comprehensive user support (e.g., ANSYS, MARC, MITAS 2 MSC/NASTRAN, SESAM-69/NV-615) to the small, special purpose codes with limited user community such as ANDES, NNTB, SAHARA, SSPTA, TACO, TEPSA AND TRUMP. The capabilities of the programs surveyed are listed in tabular form followed by a summary of the major features of each program. As with any survey of computer programs, the present one has the following limitations: (1) It is useful only in the initial selection of the programs which are most suitable for a particular application. The final selection of the program to be used should, however, be based on a detailed examination of the documentation and the literature about the program; (2) Since computer software continually changes, often at a rapid rate, some means must be found for updating this survey and maintaining some degree of currency.

  13. Gaussian short-time propagators and electron kinetics: Numerical evaluation of path-sum solutions to Fokker{endash}Planck equations for rf heating and current drive

    SciTech Connect

    Bizarro, J.P.; Belo, J.H.; Figueiredo, A.C.

    1997-06-01

    Knowing that short-time propagators for Fokker{endash}Planck equations are Gaussian, and based on a path-sum formulation, an efficient and simple numerical method is presented to solve the initial-value problem for electron kinetics during rf heating and current drive. The formulation is thoroughly presented and discussed, its advantages are stressed, and general, practical criteria for its implementation are derived regarding the time step and grid spacing. The new approach is illustrated and validated by solving the one-dimensional model for lower-hybrid current drive, which has a well-known steady-state analytical solution. {copyright} {ital 1997 American Institute of Physics.}

  14. Survey of computer programs for heat transfer analysis

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.

    1986-01-01

    An overview is given of the current capabilities of thirty-three computer programs that are used to solve heat transfer problems. The programs considered range from large general-purpose codes with broad spectrum of capabilities, large user community, and comprehensive user support (e.g., ABAQUS, ANSYS, EAL, MARC, MITAS II, MSC/NASTRAN, and SAMCEF) to the small, special-purpose codes with limited user community such as ANDES, NTEMP, TAC2D, TAC3D, TEPSA and TRUMP. The majority of the programs use either finite elements or finite differences for the spatial discretization. The capabilities of the programs are listed in tabular form followed by a summary of the major features of each program. The information presented herein is based on a questionnaire sent to the developers of each program. This information is preceded by a brief background material needed for effective evaluation and use of computer programs for heat transfer analysis. The present survey is useful in the initial selection of the programs which are most suitable for a particular application. The final selection of the program to be used should, however, be based on a detailed examination of the documentation and the literature about the program.

  15. Operation of the TFTR Pellet Charge Exchange Diagnostic in the Pulse Counting Mode during H+ RF-minority Heating

    SciTech Connect

    Medley, S.S., PPPL

    1998-05-01

    The Pellet Charge Exchange technique on TFTR has been used primarily to obtain active charge exchange measurements using a high energy (0.5 - 4.0 MeV) neutral particle analyzer (NPA) in conjunction with impurity pellet injection (Li and B) with the scintillator-photomultiplier detector system operated in the current mode. While passive measurements using pulse counting were also obtained using this instrumentation, operation in this mode was very restrictive with pulse counting rates limited to less than {approximately}10 kHz in the absence of any significant neutron and gamma induced background signal. An upgrade to a specialized pulse counting capability which was developed by the Ioffe Institute was implemented which consisted of CsI(Tl) scintillators having features designed to minimize signals induced by background neutron and gamma rays and 16-channel pulse height analysis electronics on each of the eight NPA energy channels. Passive measurements of RF-driven energetic hydrogen minority ions which served to verify operation of the pulse counting mode are reported. It is shown that in the passive mode the main donors for the neutralization of H+ ions in this energy range are C5+ ions. The measured effective H+ tail temperatures range from 0.15 MeV at an RF power of 2 MW to 0.35 MeV at 6 MW.

  16. FINAL Report on Analysis and direct numerical simulation of RF heating processes and advanced computational methods for fusion application

    SciTech Connect

    Cary, John R

    2015-02-23

    This completes the description of the work done under the above referenced grant. In brief, we have discovered many nonlinear effects, frequency doubling, nonlinear decays, that can prevent effective use of EBWs for plasma heating.

  17. Survey of heat use during peripheral IV insertion by health care workers.

    PubMed

    Kiger, Tammy; Knudsen, Élise Arsenault; Curran, Wendy; Hunter, Julia; Schaub, Anna; Williams, Mary Jane; Zechel, Janet; Kwekkeboom, Kristine

    2014-01-01

    Health care workers at an academic medical center in the Midwest were surveyed to identify common practices regarding heat use during peripheral intravenous (PIV) catheter insertion. Of the 907 who responded, the majority used heat to facilitate PIV insertion at least sometimes, when veins were not easily seen or not palpable, applying a commercial dry hot pack for 2 to 5 minutes before selecting an insertion site. Heat use correlated with practice role and population, frequency of PIV insertion, and perceived PIV skill. Findings will guide development of a research protocol to compare the effects of dry heat, moist heat, and no heat on PIV insertion success.

  18. Heat pump water heaters: A technology assessment and market survey

    SciTech Connect

    Nisson, N.; Shepard, M.

    1994-12-31

    Heat pump water heaters (HPWHs) are two to four times as efficient as electric resistance water heaters and provide space cooling as well as water heating. They also cost considerably more, consume more space, and may require more maintenance. Their low operating costs make them an attractive option in hotels, apartment buildings, restaurants, laundries, and other settings where there are simultaneous demands for space cooling and water heating. In such settings they often pay back in less than two years relative to resistance water heating and can be more economical than gas water heating. In houses, the economics are highly variable, with paybacks ranging from less than two years to more than twenty years, depending on climate, water use patterns, and other factors. HPWHs can be a peak shaving option for utilities whose daily peak coincides with the residential morning water heating peak. Residential units draw 500 to 800 watts, compared to 4,500 watts or more for resistance water heaters. Heat pump water heaters hold a tiny share of the water heating market, but their profile is rising, due in part to a controversial water heating standard proposed in the United States. Six North American manufacturers currently produce nearly 50 models for residential and commercial applications, and several new players will enter the market in 1995. Scant field data exist on the performance of currently available models, but more information will become available over the coming year from several utility demonstration, monitoring, and incentive programs.

  19. Numerical study of plasma generation process and internal antenna heat loadings in J-PARC RF negative ion source

    NASA Astrophysics Data System (ADS)

    Shibata, T.; Nishida, K.; Mochizuki, S.; Mattei, S.; Lettry, J.; Hatayama, A.; Ueno, A.; Oguri, H.; Ohkoshi, K.; Ikegami, K.; Takagi, A.; Asano, H.; Naito, F.

    2016-02-01

    A numerical model of plasma transport and electromagnetic field in the J-PARC (Japan Proton Accelerator Research Complex) radio frequency ion source has been developed to understand the relation between antenna coil heat loadings and plasma production/transport processes. From the calculation, the local plasma density increase is observed in the region close to the antenna coil. Electrons are magnetized by the magnetic field line with absolute magnetic flux density 30-120 Gauss which leads to high local ionization rate. The results suggest that modification of magnetic configuration can be made to reduce plasma heat flux onto the antenna.

  20. Numerical study of plasma generation process and internal antenna heat loadings in J-PARC RF negative ion source.

    PubMed

    Shibata, T; Nishida, K; Mochizuki, S; Mattei, S; Lettry, J; Hatayama, A; Ueno, A; Oguri, H; Ohkoshi, K; Ikegami, K; Takagi, A; Asano, H; Naito, F

    2016-02-01

    A numerical model of plasma transport and electromagnetic field in the J-PARC (Japan Proton Accelerator Research Complex) radio frequency ion source has been developed to understand the relation between antenna coil heat loadings and plasma production/transport processes. From the calculation, the local plasma density increase is observed in the region close to the antenna coil. Electrons are magnetized by the magnetic field line with absolute magnetic flux density 30-120 Gauss which leads to high local ionization rate. The results suggest that modification of magnetic configuration can be made to reduce plasma heat flux onto the antenna. PMID:26932010

  1. RF transformer

    DOEpatents

    Smith, James L.; Helenberg, Harold W.; Kilsdonk, Dennis J.

    1979-01-01

    There is provided an improved RF transformer having a single-turn secondary of cylindrical shape and a coiled encapsulated primary contained within the secondary. The coil is tapered so that the narrowest separation between the primary and the secondary is at one end of the coil. The encapsulated primary is removable from the secondary so that a variety of different capacity primaries can be utilized with one secondary.

  2. Survey and evaluation of available thermal insulation materials for use on solar heating and cooling systems

    SciTech Connect

    Not Available

    1980-03-01

    This is the final report of a survey and evaluation of insulation materials for use with components of solar heating and cooling systems. The survey was performed by mailing questionnaires to manufacturers of insulation materials and by conducting an extensive literature search to obtain data on relevant properties of various types of insulation materials. The study evaluated insulation materials for active and passive solar heating and cooling systems and for multifunction applications. Primary and secondary considerations for selecting insulation materials for various components of solar heating and cooling systems are presented.

  3. Reducing RF-related heating of cardiac pacemaker leads in MRI: implementation and experimental verification of practical design changes.

    PubMed

    Nordbeck, Peter; Fidler, Florian; Friedrich, Michael T; Weiss, Ingo; Warmuth, Marcus; Gensler, Daniel; Herold, Volker; Geistert, Wolfgang; Jakob, Peter M; Ertl, Georg; Ritter, Oliver; Ladd, Mark E; Bauer, Wolfgang R; Quick, Harald H

    2012-12-01

    There are serious concerns regarding safety when performing magnetic resonance imaging in patients with implanted conductive medical devices, such as cardiac pacemakers, and associated leads, as severe incidents have occurred in the past. In this study, several approaches for altering an implant's lead design were systematically developed and evaluated to enhance the safety of implanted medical devices in a magnetic resonance imaging environment. The individual impact of each design change on radiofrequency heating was then systematically investigated in functional lead prototypes at 1.5 T. Radiofrequency-induced heating could be successfully reduced by three basic changes in conventional pacemaker lead design: (1) increasing the lead tip area, (2) increasing the lead conductor resistance, and (3) increasing outer lead insulation conductivity. The findings show that radiofrequency energy pickup in magnetic resonance imaging can be reduced and, therefore, patient safety can be improved with dedicated construction changes according to a "safe by design" strategy. Incorporation of the described alterations into implantable medical devices such as pacemaker leads can be used to help achieve favorable risk-benefit-ratios when performing magnetic resonance imaging in the respective patient group.

  4. Survey of manufacturers of high-performance heat engines adaptable to solar applications

    NASA Technical Reports Server (NTRS)

    Stine, W. B.

    1984-01-01

    The results of an industry survey made during the summer of 1983 are summarized. The survey was initiated in order to develop an information base on advanced engines that could be used in the solar thermal dish-electric program. Questionnaires inviting responses were sent to 39 companies known to manufacture or integrate externally heated engines. Follow-up telephone communication ensured uniformity of response. It appears from the survey that the technology exists to produce external-heat-addition engines of appropriate size with thermal efficiencies of over 40%. Problem areas are materials and sealing.

  5. Status report on survey of alternative heat pumping technologies

    SciTech Connect

    Fischer, S.

    1998-07-01

    The Department of Energy is studying alternative heat pumping technologies to identify possible cost effective alternatives to electric driven vapor compression heat pumps, air conditioners, and chillers that could help reduce CO{sub 2} emissions. Over thirty different technologies are being considered including: engine driven systems, fuel cell powered systems, and alternative cycles. Results presented include theoretical efficiencies for all systems as well as measured performance of some commercial, prototype, or experimental systems. Theoretical efficiencies show that the alternative electric-driven technologies would have HSPFs between 4 and 8 Btu/Wh (1.2 to 2.3 W/W) and SEERs between 3 and 9.5 Btu/Wh (0.9 and 2.8 W/W). Gas-fired heat pump technologies have theoretical seasonal heating gCOPs from 1.1 to 1.7 and cooling gCOPs from 0.95 to 1.6 (a SEER 12 Btu/Wh electric air conditioner has a primary energy efficiency of approximately 1.4 W/W).

  6. Scaling of divertor power footprint width in RF-heated type-III ELMy H-mode on the EAST superconducting tokamak

    NASA Astrophysics Data System (ADS)

    Wang, L.; Guo, H. Y.; Xu, G. S.; Liu, S. C.; Gan, K. F.; Wang, H. Q.; Gong, X. Z.; Liang, Y.; Zou, X. L.; Hu, J. S.; Chen, L.; Xu, J. C.; Liu, J. B.; Yan, N.; Zhang, W.; Chen, R.; Shao, L. M.; Ding, S.; Hu, G. H.; Feng, W.; Zhao, N.; Xiang, L. Y.; Liu, Y. L.; Li, Y. L.; Sang, C. F.; Sun, J. Z.; Wang, D. Z.; Ding, H. B.; Luo, G. N.; Chen, J. L.; Gao, X.; Hu, L. Q.; Wan, B. N.; Li, J.; the EAST Team

    2014-11-01

    Dedicated experiments for the scaling of divertor power footprint width have been performed in the ITER-relevant radio-frequency (RF)-heated H-mode scheme under the lower single null, double null and upper single null divertor configurations in the Experimental Advanced Superconducting Tokamak (EAST) under lithium wall coating conditioning. A strong inverse scaling of the edge localized mode (ELM)-averaged power fall-off width with the plasma current (equivalently the poloidal field) has been demonstrated for the attached type-III ELMy H-mode as λq \\propto Ip-1.05 by various heat flux diagnostics including the divertor Langmuir probes (LPs), infra-red (IR) thermograph and reciprocating LPs on the low-field side. The IR camera and divertor LP measurements show that λq,IR ≈ {λq,div{-LPs}}/{1.3}=1.15Bp,omp-1.25 , in good agreement with the multi-machine scaling trend during the inter-ELM phase between type-I ELMs or ELM-free enhanced Dα (EDA). H-mode. However, the magnitude is nearly doubled, which may be attributed to the different operation scenarios or heating schemes in EAST, i.e., dominated by electron heating. It is also shown that the type-III ELMs only broaden the power fall-off width slightly, and the ELM-averaged width is representative for the inter-ELM period. Furthermore, the inverse Ip (Bp) scaling appears to be independent of the divertor configurations in EAST. The divertor power footprint integral width, fall-off width and dissipation width derived from EAST IR camera measurements follow the relation, λint ≅ λq + 1.64S, yielding λ_intEAST =(1.39+/- 0.03)λqEAST +(0.97+/- 0.35) mm . Detailed analysis of these three characteristic widths was carried out to shed more light on their extrapolation to ITER.

  7. The Eccentric Exoplanets: A Survey of Atmospheric Heating and Variability

    NASA Astrophysics Data System (ADS)

    Knutson, Heather; Cowan, Nicolas; Lewis, Nikole; Agol, Eric; Showman, Adam; Deming, Drake; Burrows, Adam; Fortney, Jonathan; Laughlin, Greg; Langton, Jonathan; Rastegar, Sara

    2012-09-01

    Observations of short-period gas giant planets on eccentric orbits provide a unique test of atmospheric circulation theories. Eccentric planets are qualitatively different for two reasons: 1) they cannot be synchronously rotating, so they experience diurnal forcing, and 2) the incident stellar flux changes throughout an orbit, constituting a time-variable atmospheric forcing. These differences cause large variations in planetary temperature and wind speeds as a function of time. We propose to compare thermal phase variations and instantaneous eclipse maps for two benchmark eccentric transiting planets, XO-3b and HAT-P-2b. The mirrored viewing geometry of these two systems and the close similarities in their stellar and planetary properties makes them ideal cases for comparison, as we can observe the same heating and cooling processes from opposite hemispheres. By measuring the heating responses of the two planets during periastron passage, we can determine the radiative time scales of their atmospheres independent of other parameters. The flux that we measure at a given orbital phase will be a function of both the viewing geometry and the heating history of the planet; we break this degeneracy by mapping the instantaneous dayside brightness distribution using the shape of the secondary eclipse ingress and egress. The existence of a large set of secondary eclipse measurements in the same band will also allow us to place strict limits on orbit-to-orbit variability in the planet's dayside emission. Together these data will provide a uniquely detailed picture of the atmospheres of two complementary worlds, and motivate the development of increasingly sophisticated atmospheric circulation models that can be applied to a wide range of planets.

  8. Survey of literature on convective heat transfer coefficients and recovery factors for high atmosphere thermometry

    NASA Technical Reports Server (NTRS)

    Chung, S.

    1973-01-01

    Heat transfer phenomena of rarefied gas flows is discussed based on a literature survey of analytical and experimental rarefied gas dynamics. Subsonic flows are emphasized for the purposes of meteorological thermometry in the high atmosphere. The heat transfer coefficients for three basic geometries are given in the regimes of free molecular flow, transition flow, slip flow, and continuum flow. Different types of heat phenomena, and the analysis of theoretical and experimental data are presented. The uncertainties calculated from the interpolation rule compared with the available experimental data are discussed. The recovery factor for each geometry in subsonic rarefied flows is also given.

  9. A survey of geothermal process heat applications in Guatemala: An engineering survey

    SciTech Connect

    Altseimer, J.H.; Edeskuty, F.J.

    1988-08-01

    This study investigates how process heat from Guatemala's geothermal energy resources can be developed to reduce Guatemala's costly importation of oil, create new employment by encouraging new industry, and reduce fuel costs for existing industry. This investigation was funded by the US Agency for International Development and carried out jointly by the Guatemalan Government and the Los Alamos National Laboratory. Two sites, Amatitlan and Zunil, are being developed geothermally. Amatitlan is in the better industrial area but Zunil's geothermal development is more advanced. The industry around Zunil is almost exclusively agricultural and the development of an agricultural processing plant (freezing, dehydration, and cold storage) using geothermal heat is recommended. Similar developments throughout the volcanic zones of Guatemala are possible. Later, when the field at Amatitlan has been further developed, an industrial park can be planned. Potential Amatitlan applications are the final stage of salt refining, a thermal power plant, hospital/hotel heating and cooling, steam curing of concrete blocks, production of alcohol from sugar cane, and production of polyethylene from ethanol. Other special developments such as water pumping for the city of Guatemala and the use of moderate-temperature geothermal fluids for localized power production are also possible. 12 refs., 13 figs., 14 tabs.

  10. Cryogenic vacuumm RF feedthrough device

    DOEpatents

    Wu, Genfa; Phillips, Harry Lawrence

    2008-12-30

    A cryogenic vacuum rf feedthrough device comprising: 1) a probe for insertion into a particle beam; 2) a coaxial cable comprising an inner conductor and an outer conductor, a dielectric/insulating layer surrounding the inner conductor, the latter being connected to the probe for the transmission of higher mode rf energy from the probe; and 3) a high thermal conductivity stub attached to the coaxial dielectric about and in thermal contact with the inner conductor which high thermal conductivity stub transmits heat generated in the vicinity of the probe efficiently and radially from the area of the probe and inner conductor all while maintaining useful rf transmission line characteristics between the inner and outer coaxial conductors.

  11. Glancing angle RF sheaths

    NASA Astrophysics Data System (ADS)

    D'Ippolito, D. A.; Myra, J. R.

    2013-10-01

    RF sheaths occur in tokamaks when ICRF waves encounter conducting boundaries. The sheath plays an important role in determining the efficiency of ICRF heating, the impurity influxes from the edge plasma, and the plasma-facing component damage. An important parameter in sheath theory is the angle θ between the equilibrium B field and the wall. Recent work with 1D and 2D sheath models has shown that the rapid variation of θ around a typical limiter can lead to enhanced sheath potentials and localized power deposition (hot spots) when the B field is near glancing incidence. The physics model used to obtain these results does not include some glancing-angle effects, e.g. possible modification of the angular dependence of the Child-Langmuir law and the role of the magnetic pre-sheath. Here, we report on calculations which explore these effects, with the goal of improving the fidelity of the rf sheath BC used in analytical and numerical calculations. Work supported by US DOE grants DE-FC02-05ER54823 and DE-FG02-97ER54392.

  12. Recycler barrier RF buckets

    SciTech Connect

    Bhat, C.M.; /Fermilab

    2011-03-01

    The Recycler Ring at Fermilab uses a barrier rf systems for all of its rf manipulations. In this paper, I will give an overview of historical perspective on barrier rf system, the longitudinal beam dynamics issues, aspects of rf linearization to produce long flat bunches and methods used for emittance measurements of the beam in the RR barrier rf buckets. Current rf manipulation schemes used for antiproton beam stacking and longitudinal momentum mining of the RR beam for the Tevatron collider operation are explained along with their importance in spectacular success of the Tevatron luminosity performance.

  13. Coping with heat in the city: what can we learn from a survey immediately after a hot weather period for future heat waves?

    NASA Astrophysics Data System (ADS)

    Kunz-Plapp, Tina; Schipper, Hans; Hackenbruch, Julia

    2015-04-01

    Karlsruhe is one of the hottest cities in Germany with a temperature record of 40.2°C in August 2003. In 2013, two hot weather periods with continuous heat warnings by the German Weather Service for 7 and 8 days occurred during the second half of July and first 10 days of August 2013, and in early August the temperatures in Karlsruhe almost reached again the record of 40.2°C. To understand how citizens experienced the heat and what strategies they used to cope with the heat, we conducted a questionnaire survey on subjective heat stress and coping strategies immediately after the hot weather period. Based on a holistic approach the questionnaire included questions on heat stress experience in different contexts of daily life, health impacts of the heat, coping measures, housing conditions, urban environment, living conditions, and socio-demographic characteristics. The responses of the 323 survey participants living and working in Karlsruhe show that they on average experienced the heat as rather stressful event, whereby the heat stress experienced at home was significant lower than heat stress experienced at work or in general. Regression analyses show that, among the factors included in the questionnaire, the health impairments suffered during the heat, the control belief and the coping measures implemented mainly determine heat stress experienced in general and at work. For the subjective heat stress at home, factors of the built urban environment such as heat loading of district, living in the attic or the ground floor, and heat protection elements of the inhabited building also played a role. At the same time, the way the respondents used different coping strategies in context of their daily activities and routines during heat suggests lessons to learn from this event how individual response to heat differs from responses to other types of natural hazards.

  14. State of Maine residential heating oil survey: 1995--1996 season summary

    SciTech Connect

    Elder, B.

    1996-05-01

    In Maine the cash price is surveyed, as opposed to lthe retail or charge price, as it has been identified as the price most often paid by Maine consumers. As one can see from the chart in this report, the 1995-1996 cash prices for No. 2 heating oil can be characterized as having an upward trend and much more fluctuation than last years` relatively flat line. The 1995-96 heating season started at the closing price of the previous season and for the first few weeks prices were lower than most of the 1994-95 trendline. When the weather became cooler, however, prices were on a steady incline until well into the winter. Prices leveled off for most of the rest of the season with a dramatic surge on the last week of the survey. The average statewide cash price for No. 2 heating oil this year was .861 1 cents, approximately ten cents higher than the average for 1994-1995 which was .7661 cents per gallon. It has been the observation of the SPO that during most of the 1995-1996 season, Maine`s prices showed a direct correspondence with New England rack or wholesale prices. It appeared that they never fluctuated more than 3-4 cents from each other.

  15. Thermoregulatory responses to RF energy absorption.

    PubMed

    Adair, Eleanor R; Black, David R

    2003-01-01

    This white paper combines a tutorial on the fundamentals of thermoregulation with a review of the current literature concerned with physiological thermoregulatory responses of humans and laboratory animals in the presence of radio frequency (RF) and microwave fields. The ultimate goal of research involving whole body RF exposure of intact organisms is the prediction of effects of such exposure on human beings. Most of the published research on physiological thermoregulation has been conducted on laboratory animals, with a heavy emphasis on laboratory rodents. Because their physiological heat loss mechanisms are limited, these small animals are very poor models for human beings. Basic information about the thermoregulatory capabilities of animal models relative to human capability is essential for the appropriate evaluation and extrapolation of animal data to humans. In general, reliance on data collected on humans and nonhuman primates, however fragmentary, yields a more accurate understanding of how RF fields interact with humans. Such data are featured in this review, including data from both clinic and laboratory. Featured topics include thermal sensation, human RF overexposures, exposures attending magnetic resonance imaging (MRI), predictions based on simulation models, and laboratory studies of human volunteers. Supporting data from animal studies include the thermoregulatory profile, response thresholds, physiological responses of heat production and heat loss, intense or prolonged exposure, RF effects on early development, circadian variation, and additive drug-microwave interactions. The conclusion is inescapable that humans demonstrate far superior thermoregulatory ability over other tested organisms during RF exposure at, or even above current human exposure guidelines. PMID:14628305

  16. Airborne-temperature-survey maps of heat-flow anomalies for exploration geology

    NASA Astrophysics Data System (ADS)

    Delgrande, N. K.

    1982-11-01

    Precise airborne temperature surveys depicted small predawn surface temperature differences related to heat flow anomalies at the Long Valley, California, KGRA. Zones with conductive heat flow differences of 45 + or - 16 nu cal/sq cm(s) has predawn surface temperature differences of 1.4 + or - 0.3 C. The warmer zones had hot water circulating in a shallow (less than 60-m-deep) aquifer. Hot wate is a useful geochemical indicator of geothermal and mineral resource potential. The precise airborne temperature survey method recorded redundant infrared scanner signals at two wavelengths (10 to 12 micrometers and 4.5 to 5.5 micrometers) and two elevations (0.3 km and 1.2 km). Ground thermistor probes recorded air and soil temperatures during the survey overflights. Radiometric temperatures were corrected for air path and reflected sky radiation effects. Corrected temperatures were displayed in image form with color coded maps which depicted 0.24 C temperature differences.

  17. A survey of urban heat island studies in two tropical cities

    NASA Astrophysics Data System (ADS)

    Tso, C. P.

    Studies on the urban heat island effects in two adjacent tropical cities, Singapore and Kuala Lumpur, are surveyed. Past efforts have concentrated on surface temperature mapping relying largely on spot measurements, which, although are inadequate, do indicate the existence of warm spots associated with urbanization. Examination of station records have indicated perceptible temperature increases in both cities, though there has been no concerted effort to facilitate comparative studies. Recent work includes implementation of more systematic data acquisition, the use of the remote technology, as well as surface energy balance modelling. Directions for future work is discussed.

  18. State heating oil and propane program: Final report. Survey of No.2 heating oil and propane prices at the retail level, October 1997 through March 1998

    SciTech Connect

    1998-11-01

    The Energy Efficiency Division of the Vermont Department of Public Service (DPS) monitored the price and inventory of residential heating oil and propane during the 1997--98 heating season under a grant from the US Department of Energy`s Energy Information Administration (EIA). DPS staff collected data biweekly between October 5, 1997 and March 16, 1998 on the retail price of {number_sign}2 home heating oil and propane by telephone survey. Propane price quoted was based on the rate for a residential home heating customer using 1,000+ per year. The survey included a sample of fuel dealers selected by the EIA, plus additional dealers and fuels selected by the DPS. The EIA weighted, analyzed, and reported the data collected from their sample.

  19. Rf feedback free electron laser

    DOEpatents

    Brau, C.A.; Swenson, D.A.; Boyd, T.J. Jr.

    1979-11-02

    A free electron laser system and electron beam system for a free electron laser are provided which use rf feedback to enhance efficiency. Rf energy is extracted from an electron beam by decelerating cavities and returned to accelerating cavities using rf returns such as rf waveguides, rf feedthroughs, etc. This rf energy is added to rf klystron energy to lower the required input energy and thereby enhance energy efficiency of the system.

  20. Rf Feedback free electron laser

    DOEpatents

    Brau, Charles A.; Swenson, Donald A.; Boyd, Jr., Thomas J.

    1981-01-01

    A free electron laser system and electron beam system for a free electron laser which use rf feedback to enhance efficiency. Rf energy is extracted from an electron beam by decelerating cavities and returned to accelerating cavities using rf returns such as rf waveguides, rf feedthroughs, etc. This rf energy is added to rf klystron energy to lower the required input energy and thereby enhance energy efficiency of the system.

  1. State of Maine residential heating oil survey: 1994--1995 Season summary

    SciTech Connect

    1995-04-01

    The 1994--95 heating season approached with more attention to petroleum products than experienced in some time. This year, however, the focus was on transportation fuels with the introduction of reformulated gasolines scheduled for the first of 1995. Last year transportation fuels had been in the spotlight in the Northeast as well, for the ills experienced with a new winter mix for diesel fuel. Would RFG have the same dubious entrance as diesel`s winter mix? Would RFG implementation work and what effect would the change in stocks have on the refineries? With worries related to transportation fuels being recognized, would there be reason for concern with heating fuels? As the new year approached, the refineries seemed to have no problem with supplies and RFG stocks were eased in about the second week of December. In Maine, the southern half of the state was effected by the gasoline substitution but seven of Maine`s sixteen counties were directed to follow the recommended criteria. Since the major population concentration lies in the southern three counties, concern was real. Attention paid to emission testing had come to a head in the fall, and RFG complaints were likely. There have been years when snow and cold arrived by Thanksgiving Day. In northern Maine, snow easily covers the ground before the SHOPP survey begins. The fall slipped by with no great shocks in the weather. December was more of the same, as the weather continued to favor the public. Normally the third week in January is considered the coldest time in the year, but not this year. By the end of January, two days were recorded as being more typical of winter. By March and the end of the survey season, one could only recognize that there were perhaps a few cold days this winter. Fuel prices fluctuated little through the entire heating season. There were no major problems to report and demand never placed pressure on dealers.

  2. Survey Instrument Validity Part II: Validation of a Survey Instrument Examining Athletic Trainers' Knowledge and Practice Beliefs Regarding Exertional Heat Stroke

    ERIC Educational Resources Information Center

    Burton, Laura J.; Mazerolle, Stephanie M.

    2011-01-01

    Objective: The purpose of this article is to discuss the process of developing and validating an instrument to investigate an athletic trainer's attitudes and behaviors regarding the recognition and treatment of exertional heat stroke. Background: Following up from our initial paper, which discussed the process of survey instrument design and…

  3. Market assessment for active solar heating and cooling products. Category B: A survey of decision makers in the HVAC market place. Survey instruments

    SciTech Connect

    Lilien, G. L.; Johnston, P. E.

    1980-09-01

    Telephone screener questionnaires and mail-out questionnaires for marketing surveys for solar heating and cooling equipment are presented. Questionnaires are included for the residential segment, industrial segment, HVAC professionals segment, builder/developer segment, and the commercial segment. No results are reported. (WHK)

  4. Electron heating enhancement due to plasma series resonance in a capacitively coupled RF discharge: Electrical modeling and comparison to experimental measurements

    NASA Astrophysics Data System (ADS)

    Cao, Minglu; Lu, Yijia; Cheng, Jia; Ji, Linhong

    2016-09-01

    The electron heating enhancement due to the self-excitation of the plasma series resonance in capacitively coupled plasmas is revisited by a combination of an equivalent circuit model and experiments. To improve the model accuracy, measured voltage waveforms at the powered electrode are used instead of prescribing a sinusoidal voltage supply in series with a bias capacitance. The results calculated from the electrical model are consistent with the experimental measurements performed by a Langmuir probe with verification of a microwave interferometer, at pressures of 0.2 and 0.3 Torr. High harmonics occurring in the discharge currents agree with observations in previous research. The nonlinear plasma series resonance effect is found to have a notable contribution to both ohmic and stochastic heating evaluated by the electron heating efficiencies.

  5. Unveiling the sources of disk heating in spiral galaxies with the CALIFA survey

    NASA Astrophysics Data System (ADS)

    Pinna, F.; Falcón-Barroso, J.; Martig, M.; van de Ven, G.; Lyubenova, M.; Leaman, R.

    2016-06-01

    The stellar velocity ellipsoid (SVE) quantifies the amount of velocity dispersion in the vertical, radial and azimuthal directions. Since different disk heating mechanisms (e.g. spiral arms, giant molecular clouds, mergers, etc) affect these components differently, the SVE can constrain the sources of heating in disk galaxies. At present the 3D nature of the SVE can only be directly measured in the Milky Way but, thanks to integral-field surveys like CALIFA, we are now in position to carry out the same kind of analysis in external galaxies. For this purpose, we have gathered a sample of ~30 intermediate inclined spiral galaxies along the Hubble sequence (S0 to Scd types) with high quality stellar kinematic maps. This allows us to probe the SVE for each galaxy from different line-of-sights in different regions, and thus provide strong constraints on its shape. In this presentation we relate our preliminary findings to realistic numerical simulations of disks with different formation histories (quiescent vs mergers), and to results of previous works.

  6. Multi-Physics Analysis of the Fermilab Booster RF Cavity

    SciTech Connect

    Awida, M.; Reid, J.; Yakovlev, V.; Lebedev, V.; Khabiboulline, T.; Champion, M.; /Fermilab

    2012-05-14

    After about 40 years of operation the RF accelerating cavities in Fermilab Booster need an upgrade to improve their reliability and to increase the repetition rate in order to support a future experimental program. An increase in the repetition rate from 7 to 15 Hz entails increasing the power dissipation in the RF cavities, their ferrite loaded tuners, and HOM dampers. The increased duty factor requires careful modelling for the RF heating effects in the cavity. A multi-physic analysis investigating both the RF and thermal properties of Booster cavity under various operating conditions is presented in this paper.

  7. Detection and location of leaks in district heating steam systems: Survey and review of current technology and practices

    SciTech Connect

    Kupperman, D.S.; Raptis, A.C.; Lanham, R.N.

    1992-03-01

    This report presents the results of a survey undertaken to identify and characterize current practices for detecting and locating leaks in district heating systems, particular steam systems. Currently used technology and practices are reviewed. In addition, the survey was used to gather information that may be important for the application of acoustic leak detection. A few examples of attempts to locate leaks in steam and hot water pipes by correlation of acoustic signals generated by the leaks are also discussed.

  8. The JCMT Gould Belt Survey: evidence for radiative heating and contamination in the W40 complex

    NASA Astrophysics Data System (ADS)

    Rumble, D.; Hatchell, J.; Pattle, K.; Kirk, H.; Wilson, T.; Buckle, J.; Berry, D. S.; Broekhoven-Fiene, H.; Currie, M. J.; Fich, M.; Jenness, T.; Johnstone, D.; Mottram, J. C.; Nutter, D.; Pineda, J. E.; Quinn, C.; Salji, C.; Tisi, S.; Walker-Smith, S.; Francesco, J. Di; Hogerheijde, M. R.; Ward-Thompson, D.; Bastien, P.; Bresnahan, D.; Butner, H.; Chen, M.; Chrysostomou, A.; Coude, S.; Davis, C. J.; Drabek-Maunder, E.; Duarte-Cabral, A.; Fiege, J.; Friberg, P.; Friesen, R.; Fuller, G. A.; Graves, S.; Greaves, J.; Gregson, J.; Holland, W.; Joncas, G.; Kirk, J. M.; Knee, L. B. G.; Mairs, S.; Marsh, K.; Matthews, B. C.; Moriarty-Schieven, G.; Mowat, C.; Rawlings, J.; Richer, J.; Robertson, D.; Rosolowsky, E.; Sadavoy, S.; Thomas, H.; Tothill, N.; Viti, S.; White, G. J.; Wouterloot, J.; Yates, J.; Zhu, M.

    2016-08-01

    We present SCUBA-2 450 μm and 850 μm observations of the W40 complex in the Serpens-Aquila region as part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Survey (GBS) of nearby star-forming regions. We investigate radiative heating by constructing temperature maps from the ratio of SCUBA-2 fluxes using a fixed dust opacity spectral index, β = 1.8, and a beam convolution kernel to achieve a common 14.8 arcsec resolution. We identify 82 clumps ranging between 10 and 36 K with a mean temperature of 20 ± 3 K. Clump temperature is strongly correlated with proximity to the external OB association and there is no evidence that the embedded protostars significantly heat the dust. We identify 31 clumps that have cores with densities greater than 105cm-3. 13 of these cores contain embedded Class 0/I protostars. Many cores are associated with bright-rimmed clouds seen in Herschel 70 μm images. From JCMT HARP observations of the 12CO 3-2 line, we find contamination of the 850 μm band of up to 20 per cent. We investigate the free-free contribution to SCUBA-2 bands from large-scale and ultracompact H II regions using archival VLA data and find the contribution is limited to individual stars, accounting for 9 per cent of flux per beam at 450 μm or 12 per cent at 850 μm in these cases. We conclude that radiative heating has potentially influenced the formation of stars in the Dust Arc sub-region, favouring Jeans stable clouds in the warm east and fragmentation in the cool west.

  9. A cross-sectional, randomized cluster sample survey of household vulnerability to extreme heat among slum dwellers in ahmedabad, india.

    PubMed

    Tran, Kathy V; Azhar, Gulrez S; Nair, Rajesh; Knowlton, Kim; Jaiswal, Anjali; Sheffield, Perry; Mavalankar, Dileep; Hess, Jeremy

    2013-06-18

    Extreme heat is a significant public health concern in India; extreme heat hazards are projected to increase in frequency and severity with climate change. Few of the factors driving population heat vulnerability are documented, though poverty is a presumed risk factor. To facilitate public health preparedness, an assessment of factors affecting vulnerability among slum dwellers was conducted in summer 2011 in Ahmedabad, Gujarat, India. Indicators of heat exposure, susceptibility to heat illness, and adaptive capacity, all of which feed into heat vulnerability, was assessed through a cross-sectional household survey using randomized multistage cluster sampling. Associations between heat-related morbidity and vulnerability factors were identified using multivariate logistic regression with generalized estimating equations to account for clustering effects. Age, preexisting medical conditions, work location, and access to health information and resources were associated with self-reported heat illness. Several of these variables were unique to this study. As sociodemographics, occupational heat exposure, and access to resources were shown to increase vulnerability, future interventions (e.g., health education) might target specific populations among Ahmedabad urban slum dwellers to reduce vulnerability to extreme heat. Surveillance and evaluations of future interventions may also be worthwhile.

  10. Proceedings of the DOE Planning Workshop on RF Theory and Computations

    NASA Astrophysics Data System (ADS)

    1984-01-01

    The status of RF heating in magnetic fusion plasmas was reviewed and the outstanding problems in this area were determined. The term RF heating was understood to encompass not only bulk plasma heating by externally applied electromagnetic power but also current generation in toroidal plasmas and generation of thermal barriers in tandem mirror plasmas.

  11. Microfluidic stretchable RF electronics.

    PubMed

    Cheng, Shi; Wu, Zhigang

    2010-12-01

    Stretchable electronics is a revolutionary technology that will potentially create a world of radically different electronic devices and systems that open up an entirely new spectrum of possibilities. This article proposes a microfluidic based solution for stretchable radio frequency (RF) electronics, using hybrid integration of active circuits assembled on flex foils and liquid alloy passive structures embedded in elastic substrates, e.g. polydimethylsiloxane (PDMS). This concept was employed to implement a 900 MHz stretchable RF radiation sensor, consisting of a large area elastic antenna and a cluster of conventional rigid components for RF power detection. The integrated radiation sensor except the power supply was fully embedded in a thin elastomeric substrate. Good electrical performance of the standalone stretchable antenna as well as the RF power detection sub-module was verified by experiments. The sensor successfully detected the RF radiation over 5 m distance in the system demonstration. Experiments on two-dimensional (2D) stretching up to 15%, folding and twisting of the demonstrated sensor were also carried out. Despite the integrated device was severely deformed, no failure in RF radiation sensing was observed in the tests. This technique illuminates a promising route of realizing stretchable and foldable large area integrated RF electronics that are of great interest to a variety of applications like wearable computing, health monitoring, medical diagnostics, and curvilinear electronics.

  12. Phase stable RF transport system

    DOEpatents

    Curtin, Michael T.; Natter, Eckard F.; Denney, Peter M.

    1992-01-01

    An RF transport system delivers a phase-stable RF signal to a load, such as an RF cavity of a charged particle accelerator. A circuit generates a calibration signal at an odd multiple frequency of the RF signal where the calibration signal is superimposed with the RF signal on a common cable that connects the RF signal with the load. Signal isolating diplexers are located at both the RF signal source end and load end of the common cable to enable the calibration to be inserted and extracted from the cable signals without any affect on the RF signal. Any phase shift in the calibration signal during traverse of the common cable is then functionally related to the phase shift in the RF signal. The calibration phase shift is used to control a phase shifter for the RF signal to maintain a stable RF signal at the load.

  13. RF wave propagation and scattering in turbulent tokamak plasmas

    SciTech Connect

    Horton, W. Michoski, C.; Peysson, Y.; Decker, J.

    2015-12-10

    Drift wave turbulence driven by the steep electron and ion temperature gradients in H-mode divertor tokamaks produce scattering of the RF waves used for heating and current drive. The X-ray emission spectra produced by the fast electrons require the turbulence broaden RF wave spectrum. Both the 5 GHz Lower Hybrid waves and the 170 GHz electron cyclotron [EC] RF waves experience scattering and diffraction by the electron density fluctuations. With strong LHCD there are bifurcations in the coupled turbulent transport dynamics giving improved steady-state confinement states. The stochastic scattering of the RF rays makes the prediction of the distribution of the rays and the associated particle heating a statistical problem. Thus, we introduce a Fokker-Planck equation for the probably density of the RF rays. The general frame work of the coupled system of coupled high frequency current driving rays with the low-frequency turbulent transport determines the profiles of the plasma density and temperatures.

  14. RF wave propagation and scattering in turbulent tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Horton, W.; Michoski, C.; Peysson, Y.; Decker, J.

    2015-12-01

    Drift wave turbulence driven by the steep electron and ion temperature gradients in H-mode divertor tokamaks produce scattering of the RF waves used for heating and current drive. The X-ray emission spectra produced by the fast electrons require the turbulence broaden RF wave spectrum. Both the 5 GHz Lower Hybrid waves and the 170 GHz electron cyclotron [EC] RF waves experience scattering and diffraction by the electron density fluctuations. With strong LHCD there are bifurcations in the coupled turbulent transport dynamics giving improved steady-state confinement states. The stochastic scattering of the RF rays makes the prediction of the distribution of the rays and the associated particle heating a statistical problem. Thus, we introduce a Fokker-Planck equation for the probably density of the RF rays. The general frame work of the coupled system of coupled high frequency current driving rays with the low-frequency turbulent transport determines the profiles of the plasma density and temperatures.

  15. Rheumatoid factor (RF)

    MedlinePlus

    ... infections Leukemia , multiple myeloma , and other cancers Chronic lung disease Chronic liver disease In some cases, people who are healthy and have no other medical problem will have a higher-than-normal RF level.

  16. Rf power sources

    SciTech Connect

    Allen, M.A.

    1988-05-01

    This paper covers RF power sources for accelerator applications. The approach has been 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. This paper is confined to electron-positron linear accelerators since the RF sources have always defined what is possible to achieve with these accelerators. 11 refs., 13 figs.

  17. Microbunching and RF Compression

    SciTech Connect

    Venturini, M.; Migliorati, M.; Ronsivalle, C.; Ferrario, M.; Vaccarezza, C.

    2010-05-23

    Velocity bunching (or RF compression) represents a promising technique complementary to magnetic compression to achieve the high peak current required in the linac drivers for FELs. Here we report on recent progress aimed at characterizing the RF compression from the point of view of the microbunching instability. We emphasize the development of a linear theory for the gain function of the instability and its validation against macroparticle simulations that represents a useful tool in the evaluation of the compression schemes for FEL sources.

  18. Barrier RF stacking

    SciTech Connect

    Chou, W.; Wildman, D.; Zheng, H.; Takagi, A.; /KEK, Tsukuba

    2004-12-01

    A novel wideband RF system, nicknamed the barrier RF, has been designed, fabricated and installed in the Fermilab Main Injector. The cavity is made of seven Finemet cores, and the modulator made of two bipolar high-voltage fast solid-state switches. The system can deliver {+-}7 kV square pulses at 90 kHz. The main application is to stack two proton batches injected from the Booster and squeeze them into the size of one so that the bunch intensity can be doubled. High intensity beams have been successfully stacked and accelerated to 120 GeV with small losses. The problem of large longitudinal emittance growth is the focus of the present study. An upgraded system with two barrier RF cavities for continuous stacking is under construction. This work is part of the US-Japan collaborative agreement.

  19. Barrier RF Stacking

    SciTech Connect

    Chou, W.; Wildman, D.; Zheng, H.; Takagi, A.

    2005-06-08

    A novel wideband RF system, nicknamed the barrier RF, has been designed, fabricated and installed in the Fermilab Main Injector. The cavity is made of seven Finemet cores, and the modulator made of two bipolar high-voltage fast solid-state switches. The system can deliver {+-}7 kV square pulses at 90 kHz. The main application is to stack two proton batches injected from the Booster and squeeze them into the size of one so that the bunch intensity can be doubled. High intensity beams have been successfully stacked and accelerated to 120 GeV with small losses. The problem of large longitudinal emittance growth is the focus of the present study. An upgraded system with two barrier RF cavities for continuous stacking is under construction. This work is part of the US-Japan collaborative agreement.

  20. Barrier RF Stacking

    NASA Astrophysics Data System (ADS)

    Chou, W.; Wildman, D.; Zheng, H.; Takagi, A.

    2005-06-01

    A novel wideband RF system, nicknamed the barrier RF, has been designed, fabricated and installed in the Fermilab Main Injector. The cavity is made of seven Finemet cores, and the modulator made of two bipolar high-voltage fast solid-state switches. The system can deliver ±7 kV square pulses at 90 kHz. The main application is to stack two proton batches injected from the Booster and squeeze them into the size of one so that the bunch intensity can be doubled. High intensity beams have been successfully stacked and accelerated to 120 GeV with small losses. The problem of large longitudinal emittance growth is the focus of the present study. An upgraded system with two barrier RF cavities for continuous stacking is under construction. This work is part of the US-Japan collaborative agreement.

  1. RF Gun Optimization Study

    SciTech Connect

    A. S. Hofler; P. Evtushenko; M. Krasilnikov

    2007-08-01

    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. RF and SRF gun design is further complicated because the bunches are space charge dominated and require additional emittance compensation. A genetic algorithm has been successfully used to optimize DC photo injector designs for Cornell* and Jefferson Lab**, and we propose studying how the genetic algorithm techniques can be applied 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 gun designs that have been benchmarked with beam measurements and simulation.

  2. Barrier RF stacking

    SciTech Connect

    Weiren Chou and Akira Takagi

    2003-02-24

    This paper introduces a new method for stacking beams in the longitudinal phase space. It uses RF barriers to confine and compress beams in an accelerator, provided that the machine momentum acceptance is a few times larger than the momentum spread of the injected beam. This is the case for the Fermilab Main Injector. A barrier RF system employing Finemet cores and high-voltage solid-state switches is under construction. The goal is to double the number of protons per cycle on the production target for Run2 and NuMI experiments.

  3. Rf2a and rf2b transcription factors

    DOEpatents

    Beachy, Roger N.; Petruccelli, Silvana; Dai, Shunhong

    2007-10-02

    A method of activating the rice tungro bacilliform virus (RTBV) promoter in vivo is disclosed. The RTBV promoter is activated by exposure to at least one protein selected from the group consisting of Rf2a and Rf2b.

  4. Safety assessment for the rf Test Facility

    SciTech Connect

    Nagy, A.; Beane, F.

    1984-08-01

    The Radio Frequency Test Facility (RFTF) is a part of the Magnetic Fusion Program's rf Heating Experiments. The goal of the Magnetic Fusion Program (MFP) is to develop and demonstrate the practical application of fusion. RFTF is an experimental device which will provide an essential link in the research effort aiming at the realization of fusion power. This report was compiled as a summary of the analysis done to ensure the safe operation of RFTF.

  5. The TESLA RF System

    NASA Astrophysics Data System (ADS)

    Choroba, S.

    2003-12-01

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

  6. Quad RF power meter

    SciTech Connect

    Stone, D.W.

    1987-09-01

    This report shows how to construct a four-channel RF power meter from circuit boards and components found in a Hewlett Packard Model 432A Power Meter. Included are descriptions of necessary modifications, electrical circuit diagrams, and a parts list. Each of the four power meters is compatible with a Hewlett Packard 432A Power Meter.

  7. AC/RF Superconductivity

    SciTech Connect

    Ciovati, Gianluigi

    2015-02-01

    This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.

  8. Plasma core reactor simulations using RF uranium seeded argon discharges

    NASA Technical Reports Server (NTRS)

    Roman, W. C.

    1976-01-01

    Experimental results are described in which pure uranium hexafluoride was injected into an argon-confined, steady-state, RF-heated plasma to investigate characteristics of plasma core nuclear reactors. The 80 kW (13.56 MHz) and 1.2 MW (5.51 MHz) rf induction heater facilities were used to determine a test chamber flow scheme which offered best uranium confinement with minimum wall coating. The cylindrical fused-silica test chamber walls were 5.7-cm-ID by 10-cm-long. Test conditions included RF powers of 2-85 kW, chamber pressures of 1-12 atm, and uranium hexafluoride mass-flow rates of 0.005-0.13 g/s. Successful techniques were developed for fluid-mechanical confinement of RF-heated plasmas with pure uranium hexafluoride injection.

  9. Aerial infrared surveys in the investigation of geothermal and volcanic heat sources

    USGS Publications Warehouse

    ,

    1995-01-01

    This factsheet briefly summarizes and clarifies the application of aerial infrared surveys in geophysical exploration for geothermal energy sources and environmental monitoring for potential volcanic hazards.

  10. Rapid heat-flowing surveying of geothermal areas, utilizing individual snowfalls as calorimeters

    USGS Publications Warehouse

    White, Donald E.

    1969-01-01

    Local differences in rate of heat transfer in vapor and by conduction through the ground in hot spring areas are difficult and time-consuming to measure quantitatively. Individual heavy snowfalls provide a rapid low-cost means of measuring total heat flow from such ground. After a favorable snowfall (heavy, brief duration, little wind, air temperature near 0°C), contacts between snow-covered and snow-free ground are mapped on a suitable base. Each mapped contact, as time elapses after a specific snowfall, is a heat-flow contour representing a decreasing rate of flow. Calibration of each mapped contact or snow line is made possible by the fact that snow remains on insulated surfaces (such as the boardwalks of Yellowstone's thermal areas) long after it has melted on adjacent warm ground. Heat-flow contours mapped to date range from 450 to 5500 μcal/cm2 sec, or 300 to 3700 times the world average of conductive heat flow. The very high rates of heat flow (2000 to > 10,000 μcal/cm2 sec) are probably too high, and the lower heat flows determinable by the method (2 sec) may be too low. Values indicated by the method are, however, probably within a factor of 2 of the total conductive and convective heat flow. Thermal anomalies from infrared imagery are similar in shape to heat-flow contours of a test area near Old Faithful geyser. Snowfall calorimetry provides a rapid means for evaluating the imagery and computer-derived products of the infrared data in terms of heat flow.

  11. Radio frequency heating for in-situ remediation of DNAPL

    SciTech Connect

    Kasevich, R.S.

    1996-08-01

    In-situ radio frequency (RF) heating technology for treating soils contaminated with dense nonaqueous phase liquids (DNAPLs) is described. RF imparts heat to non-conducting materials through the application of carefully controlled RF transmissions, improving contaminant flow characteristics and facilitating separation and removal from subsurface soils. The paper outlines advantages and limitations of RF remediation, process operations, general technology considerations, low permeability media considerations, commercial availability, and costs. Two case histories of RF remediation are briefly summarized. 13 refs., 10 figs.

  12. Use of residential wood heating in a context of climate change: a population survey in Québec (Canada)

    PubMed Central

    Bélanger, Diane; Gosselin, Pierre; Valois, Pierre; Abdous, Belkacem

    2008-01-01

    Background Wood heating is recommended in several countries as a climate change (CC) adaptation measure, mainly to increase the autonomy of households during power outages due to extreme climatic events. The aim of this study was to examine various perceptions and individual characteristics associated with wood heating through a survey about CC adaptations. Methods A telephone survey (n = 2,545) of adults living in the southern part of the province of Québec (Canada) was conducted in the early fall season of 2005. The questionnaire used closed questions and measured the respondents' beliefs and current adaptations about CC. Calibration weighting was used to adjust the data analysis for the respondent's age and language under stratified sampling based on health regions. Results More than three out of four respondents had access to a single source of energy at home, which was mainly electricity; 22.2% combined two sources or more; 18.5% heated with wood occasionally or daily during the winter. The prevalence of wood heating was higher in the peripheral regions than in the more urban regions, where there was a higher proportion of respondents living in apartments. The prevalence was also higher with participants completely disagreeing (38.5%) with the eventual prohibition of wood heating when there is smog in winter, compared to respondents somewhat disagreeing (24.2%) or agreeing (somewhat: 17.5%; completely: 10.4%) with the adoption of this strategy. It appears that the perception of living in a region susceptible to winter smog, smog warnings in the media, or the belief in the human contribution to CC, did not influence significantly wood heating practices. Conclusion Increased residential wood heating could very well become a maladaptation to climate change, given its known consequences on winter smog and respiratory health. It would thus be appropriate to implement a long-term national program on improved and controlled residential wood heating. This would

  13. Barrier rf systems in synchrotrons

    SciTech Connect

    Chandra M. Bhat

    2004-06-28

    Recently, many interesting applications of the barrier RF system in hadron synchrotrons have been realized. A remarkable example of this is the development of longitudinal momentum mining and implementation at the Fermilab Recycler for extraction of low emittance pbars for the Tevatron shots. At Fermilab, we have barrier RF systems in four different rings. In the case of Recycler Ring, all of the rf manipulations are carried out using a barrier RF system. Here, the author reviews various uses of barrier rf systems in particle accelerators including some new schemes for producing intense proton beam and possible new applications.

  14. SU-E-T-558: An Exploratory RF Pulse Sequence Technique Used to Induce Differential Heating in Tissues Containing Iron Oxide Nanoparticles for a Possible Hyperthermic Adjuvant Effect to Radiotherapy

    SciTech Connect

    Yee, S; Ionascu, D; Wilson, G; Thapa, R

    2014-06-01

    Purpose: In pre-clinical trials of cancer thermotherapy, hyperthermia can be induced by exposing localized super-paramagnetic iron oxide nanoparticles (SPION) to external alternating magnetic fields generated by a solenoid electrical circuit (Zhao et al., Theranostics 2012). Alternatively, an RF pulse technique implemented in a regular MRI system is explored as a possible hyperthermia induction technique . Methods: A new thermal RF pulse sequence was developed using the Philips pulse programming tool for the 3T Ingenia MRI system to provide a sinusoidal magnetic field alternating at the frequency of 1.43 kHz (multiples of sine waves of 0.7 ms period) before each excitation RF pulse for imaging. The duration of each thermal RF pulse routine was approximately 3 min, and the thermal pulse was applied multiple times to a phantom that contains different concentrations (high, medium and low) of SPION samples. After applying the thermal pulse each time, the temperature change was estimated by measuring the phase changes in the T1-weighted inversion-prepared multi-shot turbo field echo (TFE) sequence (TR=5.5 ms, TE=2.7 ms, inversion time=200 ms). Results: The phase values and relative differences among them changed as the number of applied thermal RF pulses increased. After the 5th application of the thermal RF pulse, the relative phase differences increased significantly, suggesting the thermal activation of the SPION. The increase of the phase difference was approximately linear with the SPION concentration. Conclusion: A sinusoidal RF pulse from the MRI system may be utilized to selectively thermally activate tissues containing super-paramagnetic iron oxide nanoparticles.

  15. RF Gun Optimization Study

    SciTech Connect

    Alicia Hofler; Pavel Evtushenko

    2007-07-03

    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.

  16. Racetrack microtron rf system

    SciTech Connect

    Tallerico, P.J.; Keffeler, D.R.

    1985-01-01

    The rf system for the National Bureau of Standards (NBS)/Los Alamos cw racetrack microtron is described. The low-power portion consists of five 75-W amplifers that drive two input ports in each of two chopper deflection cavities and one port in the prebuncher cavity. A single 500-kW klystron drives four separate 2380-MHz cavity sections: the two main accelerator sections, a capture section, and a preaccelerator section. The phases and amplitudes in all cavities are controlled by electronic or electromechanical controls. The 1-MW klystron power supply and crowbar system were purchased as a unit; several modifications are described that improve power-supply performance. The entire rf system has been tested and shipped to the NBS, and the chopper-buncher system has been operated with beam at the NBS. 5 refs., 2 figs.

  17. RF pulse compression development

    SciTech Connect

    Farkas, Z.D.; Weaver, J.N.

    1987-10-01

    The body of this paper discusses the theory and some rules for designing a multistage Binary Energy Compressor (BEC) including its response to nonstandard phase coding, describes some proof-of-principle experiments with a couple of low power BECs, presents the design parameters for some sample linear collider rf systems that could possibly use a BEC to advantage and outlines in the conclusion some planned R and D efforts. 8 refs., 26 figs., 4 tabs.

  18. RF experiments on spherical torus plasmas

    SciTech Connect

    Majeski, R.; Menard, J.; Batchelor, D.; Bigelow, T.; Carter, M. D.; Finkenthal, M.; Jaeger, E. F.; Jones, B.; Kaita, R.; Mau, T. K.

    1999-09-20

    Experimental operations are about to begin on the next generation of spherical torus (ST) devices-the National Spherical Torus eXperiment (NSTX) in the U.S. and the Mega-Amp Spherical Torus (MAST) in the U.K. The application of RF heating and current drive to these high beta, compact confinement devices is a challenging problem. The initial focus for NSTX had been on the High Harmonic Fast Wave (HHFW) regime. Although modeling of HHFW heating and current drive has been performed at ORNL, UCSD, MIT, and PPPL, there are few experiments in this frequency range. In conventional tokamaks, the DIII-D experiments at the 5{sup th}-7{sup th} cyclotron harmonic are the closest approach to the HHFW regime. In an ST, the only RF heating experiments to date have been performed at the 15{sup th} harmonic on the Current Drive eXperiment-Upgrade (CDX-U) at PPPL. General features of HHFW heating and current drive and the degree to which experimental confirmation of these features is available will be discussed. (c) 1999 American Institute of Physics.

  19. ILC RF System R and D

    SciTech Connect

    Adolphsen, Chris; /SLAC

    2012-07-03

    The Linac Group at SLAC is actively pursuing a broad range of R&D to improve the reliability and reduce the cost of the L-band (1.3 GHz) rf system proposed for the ILC linacs. Current activities include the long-term evaluation of a 120 kV Marx Modulator driving a 10 MW Multi-Beam Klystron, design of a second-generation Marx Modulator, testing of a sheet-beam gun and beam transport system for a klystron, construction of an rf distribution system with remotely-adjustable power tapoffs, and development of a system to combine the power from many klystrons in low-loss circular waveguide where it would be tapped-off periodically to power groups of cavities. This paper surveys progress during the past few years.

  20. Plasma core reactor simulations using RF uranium seeded argon discharges

    NASA Technical Reports Server (NTRS)

    Roman, W. C.

    1975-01-01

    An experimental investigation was conducted using the United Technologies Research Center (UTRC) 80 kW and 1.2 MW RF induction heater systems to aid in developing the technology necessary for designing a self-critical fissioning uranium plasma core reactor (PCR). A nonfissioning, steady-state RF-heated argon plasma seeded with pure uranium hexafluoride (UF6) was used. An overall objective was to achieve maximum confinement of uranium vapor within the plasma while simultaneously minimizing the uranium compound wall deposition. Exploratory tests were conducted using the 80 kW RF induction heater with the test chamber at approximately atmospheric pressure and discharge power levels on the order of 10 kW. Four different test chamber flow configurations were tested to permit selection of the configuration offering the best confinement characteristics for subsequent tests at higher pressure and power in the 1.2 MW RF induction heater facility.

  1. RF system for ''TARN II''

    SciTech Connect

    Sato, K.; Fujita, M.; Itano, A.; Kanazawa, M.; Kodaira, M.; Kurihara, T.; Tojyo, E.; Watanabe, S.; Yamazaki, N.; Yoshizawa, M.

    1985-10-01

    An rf acceleration system for the INS heavy-ion synchrotron proposal is being developed. The rf characteristics of full-size ferrite toroids have been measured in a test cavity to study tunable frequencies of an rf cavity. It is estimated from the measurement on the ferrite material TDK SY-6 that a single-gap rf cavity based upon two ferrite-loaded quarter-wave coaxial resonators with four turns each of main and supplementary bias windings will give frequencies of 0.71-7.02 MHz for adiabatic capture and of 0.86-8.00 MHz for synchronous capture. RF acceleration parameters and design features of the rf cavity are presented.

  2. Tomcat-Projects_RF

    2004-09-15

    Tomcat-Projects_RF is a software package for analyzing sensor data obtained from a database and displaying the results with Java Servlet Pages (JSP). SQL Views into the dataset are tailored for personnel having different roles in monitoring the items in a storage facility. For example, an inspector, a host treaty compliance officer, a system engineer and software developers were the users identified that would need to access data at different levels of detail, The analysis providesmore » a high level status of the storage facility and allows the user to go deeper into the data details if the user desires.« less

  3. Tomcat-Projects_RF

    SciTech Connect

    Warrant, Marilyn M.; Garcia, Rudy J.; Zhang, Pengchu; Arms, Robert M.; Herzer, John A.; Conrad, Gregory N.; Brabson, John M.

    2004-09-15

    Tomcat-Projects_RF is a software package for analyzing sensor data obtained from a database and displaying the results with Java Servlet Pages (JSP). SQL Views into the dataset are tailored for personnel having different roles in monitoring the items in a storage facility. For example, an inspector, a host treaty compliance officer, a system engineer and software developers were the users identified that would need to access data at different levels of detail, The analysis provides a high level status of the storage facility and allows the user to go deeper into the data details if the user desires.

  4. RF Modal Quantity Gaging

    NASA Technical Reports Server (NTRS)

    Vanleuven, K.

    1989-01-01

    The primary objective is to provide a concept of a radio frequency (RF) modal resonance technique which is being investigated as a method for gaging the quantities of subcritical cryogenic propellants in metallic tanks. Of special interest are the potential applications of the technique to microgravity propellant gaging situations. The results of concept testing using cryogenic oxygen, hydrogen, and nitrogen, as well as paraffin simulations of microgravity fluid orientations, are reported. These test results were positive and showed that the gaging concept was viable.

  5. RF current sensor

    DOEpatents

    Moore, James A.; Sparks, Dennis O.

    1998-11-10

    An RF sensor having a novel current sensing probe and a voltage sensing probe to measure voltage and current. The current sensor is disposed in a transmission line to link all of the flux generated by the flowing current in order to obtain an accurate measurement. The voltage sensor is a flat plate which operates as a capacitive plate to sense voltage on a center conductor of the transmission line, in which the measured voltage is obtained across a resistance leg of a R-C differentiator circuit formed by the characteristic impedance of a connecting transmission line and a capacitance of the plate, which is positioned proximal to the center conductor.

  6. Occurrence of benzene as a heat-induced contaminant of carrot juice for babies in a general survey of beverages.

    PubMed

    Lachenmeier, Dirk W; Reusch, Helmut; Sproll, Constanze; Schoeberl, Kerstin; Kuballa, Thomas

    2008-10-01

    A survey of benzene contamination of 451 beverage samples, using headspace sampling combined with gas chromatography and mass spectrometry (HS-GC/MS) with a quantification limit of 0.13 microg l(-1), was conducted. Artefactual benzene formation during headspace sampling was excluded by gentle heating at 50 degrees C only and adjustment of sample pH to 10. The incidence of benzene contamination in soft drinks, beverages for babies, alcopops and beer-mixed drinks was relatively low, with average concentrations below the EU drinking-water limit of 1 microg l(-1). Significantly higher concentrations were only found in carrot juice, with the highest levels in carrot juice specifically intended for infants. About 94% of 33 carrot juice for infants had detectable benzene levels, with an average concentration of 1.86 +/- 1.05 microg l(-1). Benzene contamination of beverages was significantly correlated to iron and copper concentrations, which act as catalyst in benzene formation. The formation of benzene in carrot juice was predominantly caused by a heat-induced mechanism, which explains the higher levels in infant carrot juices that are subject to higher heat-treatment to exclude microbiological contamination. PMID:18608484

  7. Ion source with external RF antenna

    DOEpatents

    Leung, Ka-Ngo; Ji, Qing; Wilde, Stephen

    2005-12-13

    A radio frequency (RF) driven plasma ion source has an external RF antenna, i.e. the RF antenna is positioned outside the plasma generating chamber rather than inside. The RF antenna is typically formed of a small diameter metal tube coated with an insulator. An external RF antenna assembly is used to mount the external RF antenna to the ion source. The RF antenna tubing is wound around the external RF antenna assembly to form a coil. The external RF antenna assembly is formed of a material, e.g. quartz, which is essentially transparent to the RF waves. The external RF antenna assembly is attached to and forms a part of the plasma source chamber so that the RF waves emitted by the RF antenna enter into the inside of the plasma chamber and ionize a gas contained therein. The plasma ion source is typically a multi-cusp ion source.

  8. The MUCOOL RF Program

    SciTech Connect

    Norem, J.; Bross, A.; Moretti, A.; Norris, B.; Qian, Z.; Torun, Y.; Rimmer, R.; Li, D.; Virostek, S.; Zisman, M.; Sandstrom, R.; /Geneva U.

    2006-06-26

    Efficient muon cooling requires high RF gradients in the presence of high (3T) solenoidal fields. The Muon Ionization Cooling Experiment (MICE) also requires that the x-ray production from these cavities is low, in order to minimize backgrounds in the particle detectors that must be located near the cavities. These cavities require thin Be windows to ensure the highest fields on the beam axis. In order to develop these cavities, the MUCOOL RF Program was started about 6 years ago. Initial measurements were made on a six-cell cavity and a single-cell pillbox, both operating at 805 MHz. We have now begun measurements of a 201 MHz pillbox cavity. This program has led to new techniques to look at dark currents, a new model for breakdown and a general model of cavity performance based on surface damage. The experimental program includes studies of thin Be windows, conditioning, dark current production from different materials, magnetic-field effects and breakdown.

  9. Report of results of benchmarking survey of central heating operations at NASA centers and various corporations

    NASA Technical Reports Server (NTRS)

    Hoffman, Thomas R.

    1995-01-01

    In recent years, Total Quality Management has swept across the country. Many companies and the Government have started looking at every aspect on how business is done and how money is spent. The idea or goal is to provide a service that is better, faster and cheaper. The first step in this process is to document or measure the process or operation as it stands now. For Lewis Research Center, this report is the first step in the analysis of heating plant operations. This report establishes the original benchmark that can be referred to in the future. The report also provides a comparison to other organization's heating plants to help in the brainstorming of new ideas. The next step is to propose and implement changes that would meet the goals as mentioned above. After the changes have been implemented the measuring process starts over again. This provides for a continuous improvement process.

  10. Report of results of benchmarking survey of central heating operations at NASA centers and various corporations

    NASA Astrophysics Data System (ADS)

    Hoffman, Thomas R.

    1995-08-01

    In recent years, Total Quality Management has swept across the country. Many companies and the Government have started looking at every aspect on how business is done and how money is spent. The idea or goal is to provide a service that is better, faster and cheaper. The first step in this process is to document or measure the process or operation as it stands now. For Lewis Research Center, this report is the first step in the analysis of heating plant operations. This report establishes the original benchmark that can be referred to in the future. The report also provides a comparison to other organization's heating plants to help in the brainstorming of new ideas. The next step is to propose and implement changes that would meet the goals as mentioned above. After the changes have been implemented the measuring process starts over again. This provides for a continuous improvement process.

  11. A Micromechanical RF Channelizer

    NASA Astrophysics Data System (ADS)

    Akgul, Mehmet

    The power consumption of a radio generally goes as the number and strength of the RF signals it must process. In particular, a radio receiver would consume much less power if the signal presented to its electronics contained only the desired signal in a tiny percent bandwidth frequency channel, rather than the typical mix of signals containing unwanted energy outside the desired channel. Unfortunately, a lack of filters capable of selecting single channel bandwidths at RF forces the front-ends of contemporary receivers to accept unwanted signals, and thus, to operate with sub-optimal efficiency. This dissertation focuses on the degree to which capacitive-gap transduced micromechanical resonators can achieve the aforementioned RF channel-selecting filters. It aims to first show theoretically that with appropriate scaling capacitive-gap transducers are strong enough to meet the needed coupling requirements; and second, to fully detail an architecture and design procedure needed to realize said filters. Finally, this dissertation provides an actual experimentally demonstrated RF channel-select filter designed using the developed procedures and confirming theoretical predictions. Specifically, this dissertation introduces four methods that make possible the design and fabrication of RF channel-select filters. The first of these introduces a small-signal equivalent circuit for parallel-plate capacitive-gap transduced micromechanical resonators that employs negative capacitance to model the dependence of resonance frequency on electrical stiffness in a way that facilitates the analysis of micromechanical circuits loaded with arbitrary electrical impedances. The new circuit model not only correctly predicts the dependence of electrical stiffness on the impedances loading the input and output electrodes of parallel-plate capacitive-gap transduced micromechanical device, but does so in a visually intuitive way that identifies current drive as most appropriate for

  12. RF MEMS Based Reconfigurable Antennas

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.

    2004-01-01

    The presentation will first of all address the advantages of RF MEMS circuit in antenna applications and also the need for electronically reconfigurable antennas. Next, discuss some of the recent examples of RF MEMS based reconfigurable microstrip antennas. Finally, conclude the talk with a summary of MEMS antenna performance.

  13. NSLS-II RF SYSTEMS

    SciTech Connect

    Rose, J.; Gash, W.; Holub, B.; Kawashima, Y.; Ma, H.; Towne, N.; Yeddulla, M.

    2011-03-28

    The NSLS-II is a new third generation light source being constructed at Brookhaven Lab. The storage ring is optimized for low emittance by use of damping wigglers to reduce the emittance to below 1 nm-rad. The RF systems are designed to provide stable beam through tight RF phase and amplitude stability requirements.

  14. An RF dosimeter for independent SAR measurement in MRI scanners

    SciTech Connect

    Qian, Di; Bottomley, Paul A.; El-Sharkawy, AbdEl-Monem M.; Edelstein, William A.

    2013-12-15

    Purpose: The monitoring and management of radio frequency (RF) exposure is critical for ensuring magnetic resonance imaging (MRI) safety. Commercial MRI scanners can overestimate specific absorption rates (SAR) and improperly restrict clinical MRI scans or the application of new MRI sequences, while underestimation of SAR can lead to tissue heating and thermal injury. Accurate scanner-independent RF dosimetry is essential for measuring actual exposure when SAR is critical for ensuring regulatory compliance and MRI safety, for establishing RF exposure while evaluating interventional leads and devices, and for routine MRI quality assessment by medical physicists. However, at present there are no scanner-independent SAR dosimeters. Methods: An SAR dosimeter with an RF transducer comprises two orthogonal, rectangular copper loops and a spherical MRI phantom. The transducer is placed in the magnet bore and calibrated to approximate the resistive loading of the scanner's whole-body birdcage RF coil for human subjects in Philips, GE and Siemens 3 tesla (3T) MRI scanners. The transducer loop reactances are adjusted to minimize interference with the transmit RF field (B{sub 1}) at the MRI frequency. Power from the RF transducer is sampled with a high dynamic range power monitor and recorded on a computer. The deposited power is calibrated and tested on eight different MRI scanners. Whole-body absorbed power vs weight and body mass index (BMI) is measured directly on 26 subjects. Results: A single linear calibration curve sufficed for RF dosimetry at 127.8 MHz on three different Philips and three GE 3T MRI scanners. An RF dosimeter operating at 123.2 MHz on two Siemens 3T scanners required a separate transducer and a slightly different calibration curve. Measurement accuracy was ∼3%. With the torso landmarked at the xiphoid, human adult whole‑body absorbed power varied approximately linearly with patient weight and BMI. This indicates that whole-body torso SAR is on

  15. An Orbiting Standards Platform for communication satellite system RF measurements

    NASA Technical Reports Server (NTRS)

    Wallace, R. G.; Woodruff, J. J.

    1978-01-01

    The Orbiting Standards Platform (OSP) is a proposed satellite dedicated to performing RF measurements on space communications systems. It would consist of a quasi-geostationary spacecraft containing an ensemble of calibrated RF sources and field strength meters operating in several microwave bands, and would be capable of accurately and conveniently measuring critical earth station and satellite RF performance parameters, such as EIRP, gain, figure of merit (G/T), crosspolarization, beamwidth, and sidelobe levels. The feasibility and utility of the OSP concept has been under joint study by NASA, NBS, Comsat and NTIA. A survey of potential OSP users was conducted by NTIA as part of this effort. The response to this survey, along with certain trends in satellite communications system design, indicates a growing need for such a measurement service.

  16. A survey of electron Bernstein wave heating and current drive potential for spherical tokamaks

    NASA Astrophysics Data System (ADS)

    Urban, Jakub; Decker, Joan; Peysson, Yves; Preinhaelter, Josef; Shevchenko, Vladimir; Taylor, Gary; Vahala, Linda; Vahala, George

    2011-08-01

    The electron Bernstein wave (EBW) is typically the only wave in the electron cyclotron (EC) range that can be applied in spherical tokamaks for heating and current drive (H&CD). Spherical tokamaks (STs) operate generally in high-β regimes, in which the usual EC O- and X-modes are cut off. In this case, EBWs seem to be the only option that can provide features similar to the EC waves—controllable localized H&CD that can be used for core plasma heating as well as for accurate plasma stabilization. The EBW is a quasi-electrostatic wave that can be excited by mode conversion from a suitably launched O- or X-mode; its propagation further inside the plasma is strongly influenced by the plasma parameters. These rather awkward properties make its application somewhat more difficult. In this paper we perform an extensive numerical study of EBW H&CD performance in four typical ST plasmas (NSTX L- and H-mode, MAST Upgrade, NHTX). Coupled ray-tracing (AMR) and Fokker-Planck (LUKE) codes are employed to simulate EBWs of varying frequencies and launch conditions, which are the fundamental EBW parameters that can be chosen and controlled. Our results indicate that an efficient and universal EBW H&CD system is indeed viable. In particular, power can be deposited and current reasonably efficiently driven across the whole plasma radius. Such a system could be controlled by a suitably chosen launching antenna vertical position and would also be sufficiently robust.

  17. The JCMT Gould Belt Survey: evidence for radiative heating in Serpens MWC 297 and its influence on local star formation

    NASA Astrophysics Data System (ADS)

    Rumble, D.; Hatchell, J.; Gutermuth, R. A.; Kirk, H.; Buckle, J.; Beaulieu, S. F.; Berry, D. S.; Broekhoven-Fiene, H.; Currie, M. J.; Fich, M.; Jenness, T.; Johnstone, D.; Mottram, J. C.; Nutter, D.; Pattle, K.; Pineda, J. E.; Quinn, C.; Salji, C.; Tisi, S.; Walker-Smith, S.; Francesco, J. Di; Hogerheijde, M. R.; Ward-Thompson, D.; Allen, L. E.; Cieza, L. A.; Dunham, M. M.; Harvey, P. M.; Stapelfeldt, K. R.; Bastien, P.; Butner, H.; Chen, M.; Chrysostomou, A.; Coude, S.; Davis, C. J.; Drabek-Maunder, E.; Duarte-Cabral, A.; Fiege, J.; Friberg, P.; Friesen, R.; Fuller, G. A.; Graves, S.; Greaves, J.; Gregson, J.; Holland, W.; Joncas, G.; Kirk, J. M.; Knee, L. B. G.; Mairs, S.; Marsh, K.; Matthews, B. C.; Moriarty-Schieven, G.; Rawlings, J.; Richer, J.; Robertson, D.; Rosolowsky, E.; Sadavoy, S.; Thomas, H.; Tothill, N.; Viti, S.; White, G. J.; Wilson, C. D.; Wouterloot, J.; Yates, J.; Zhu, M.

    2015-04-01

    We present SCUBA-2 450 and 850 μm observations of the Serpens MWC 297 region, part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Survey of nearby star-forming regions. Simulations suggest that radiative feedback influences the star formation process and we investigate observational evidence for this by constructing temperature maps. Maps are derived from the ratio of SCUBA-2 fluxes and a two-component model of the JCMT beam for a fixed dust opacity spectral index of β = 1.8. Within 40 arcsec of the B1.5Ve Herbig star MWC 297, the submillimetre fluxes are contaminated by free-free emission with a spectral index of 1.03 ± 0.02, consistent with an ultracompact H II region and polar winds/jets. Contamination accounts for 73 ± 5 per cent and 82 ± 4 per cent of peak flux at 450 μm and 850 μm, respectively. The residual thermal disc of the star is almost undetectable at these wavelengths. Young stellar objects (YSOs) are confirmed where SCUBA-2 850 μm clumps identified by the FELLWALKER algorithm coincide with Spitzer Gould Belt Survey detections. We identify 23 objects and use Tbol to classify nine YSOs with masses 0.09 to 5.1 M⊙. We find two Class 0, one Class 0/I, three Class I and three Class II sources. The mean temperature is 15 ± 2 K for the nine YSOs and 32 ± 4 K for the 14 starless clumps. We observe a starless clump with an abnormally high mean temperature of 46 ± 2 K and conclude that it is radiatively heated by the star MWC 297. Jeans stability provides evidence that radiative heating by the star MWC 297 may be suppressing clump collapse.

  18. Shielding for thermoacoustic tomography with RF excitation

    NASA Astrophysics Data System (ADS)

    Mitchell, M.; Becker, G.; Dey, P.; Generotzky, J.; Patch, S. K.

    2008-02-01

    Radiofrequency (RF) pulses used to generate thermoacoustic computerized tomography (TCT) signal couple directly into the pulser-receiver and oscilloscope, swamping true TCT signal. We use a standard RF enclosure housing both RF amplifier and object being imaged. This is similar to RF shielding of magnetic resonance imaging (MRI) suites and protects electronics outside from stray RF. Unlike MRI, TCT receivers are ultrasound transducers, which must also be shielded from RF. A transducer housing that simultaneously shields RF and permits acoustic transmission was developed specifically for TCT. We compare TCT signals measured with and without RF shielding.

  19. A survey of gas-side fouling in industrial heat-transfer equipment

    NASA Technical Reports Server (NTRS)

    Marner, W. J.; Suitor, J. W.

    1983-01-01

    Gas-side fouling and corrosion problems occur in all of the energy intensive industries including the chemical, petroleum, primary metals, pulp and paper, glass, cement, foodstuffs, and textile industries. Topics of major interest include: (1) heat exchanger design procedures for gas-side fouling service; (2) gas-side fouling factors which are presently available; (3) startup and shutdown procedures used to minimize the effects of gas-side fouling; (4) gas-side fouling prevention, mitigation, and accommodation techniques; (5) economic impact of gas-side fouling on capital costs, maintenance costs, loss of production, and energy losses; and (6) miscellaneous considerations related to gas-side fouling. The present state-of-the-art for industrial gas-side fouling is summarized by a list of recommendations for further work in this area.

  20. A Micromechanical RF Channelizer

    NASA Astrophysics Data System (ADS)

    Akgul, Mehmet

    The power consumption of a radio generally goes as the number and strength of the RF signals it must process. In particular, a radio receiver would consume much less power if the signal presented to its electronics contained only the desired signal in a tiny percent bandwidth frequency channel, rather than the typical mix of signals containing unwanted energy outside the desired channel. Unfortunately, a lack of filters capable of selecting single channel bandwidths at RF forces the front-ends of contemporary receivers to accept unwanted signals, and thus, to operate with sub-optimal efficiency. This dissertation focuses on the degree to which capacitive-gap transduced micromechanical resonators can achieve the aforementioned RF channel-selecting filters. It aims to first show theoretically that with appropriate scaling capacitive-gap transducers are strong enough to meet the needed coupling requirements; and second, to fully detail an architecture and design procedure needed to realize said filters. Finally, this dissertation provides an actual experimentally demonstrated RF channel-select filter designed using the developed procedures and confirming theoretical predictions. Specifically, this dissertation introduces four methods that make possible the design and fabrication of RF channel-select filters. The first of these introduces a small-signal equivalent circuit for parallel-plate capacitive-gap transduced micromechanical resonators that employs negative capacitance to model the dependence of resonance frequency on electrical stiffness in a way that facilitates the analysis of micromechanical circuits loaded with arbitrary electrical impedances. The new circuit model not only correctly predicts the dependence of electrical stiffness on the impedances loading the input and output electrodes of parallel-plate capacitive-gap transduced micromechanical device, but does so in a visually intuitive way that identifies current drive as most appropriate for

  1. Spectroscopy of {sup 257}Rf

    SciTech Connect

    Qian, J.; Heinz, A.; Winkler, R.; Khoo, T. L.; Janssens, R. V. F.; Peterson, D.; Seweryniak, D.; Ahmad, I.; Back, B. B.; Carpenter, M. P.; Greene, J. P.; Jiang, C. L.; Kondev, F. G.; Lauritsen, T.; Lister, C. J.; Robinson, A.; Savard, G.; Scott, R.; Vondrasek, R.; Wang, X.

    2009-06-15

    The isotope {sup 257}Rf was produced in the fusion-evaporation reaction {sup 208}Pb({sup 50}Ti,n){sup 257}Rf. Reaction products were separated and identified by mass. Delayed spectroscopy of {sup 257}Rf and its decay products was performed. A partial decay scheme with configuration assignments is proposed based on {alpha} hindrance factors. The excitation energy of the 1/2{sup +}[620] configuration in {sup 253}No is proposed. The energy of this 1/2{sup +} state in a series of N=151 isotones increases with nuclear charge, reflecting an increase in the N=152 gap. This gap is deduced to grow substantially from 850 to 1400 keV between Z=94 and 102. An isomeric state in {sup 257}Rf, with a half-life of 160{sub -31}{sup +42} {mu}s, was discovered by detecting internal conversion electrons followed by {alpha} decay. It is interpreted as a three-quasiparticle high-K isomer. A second group of internal conversion electrons, with a half-life of 4.1{sub -1.3}{sup +2.4} s, followed by {alpha} decay, was also observed. These events might originate from the decay of excited states in {sup 257}Lr, populated by electron-capture decay of {sup 257}Rf. Fission of {sup 257}Rf was unambiguously detected, with a branching ratio of b{sub Rf}{sup SF}=0.02{+-}0.01.

  2. RF breakdown experiments at SLAC

    NASA Astrophysics Data System (ADS)

    Laurent, L.; Scheitrum, G.; Vlieks, A.; Pearson, C.; Caryotakis, G.; Luhmann, N. C.

    1999-05-01

    RF breakdown is a critical issue in the conditioning of klystrons, accelerator sections, and rf components for the next linear collider (NLC), as well as other high gradient accelerators and high power microwave sources. SLAC is conducting a series of experiments using an X-band traveling wave ring to characterize the processes and trigger mechanisms associated with rf breakdown. The goal of the research is to identify materials, processes, and manufacturing methods that will increase the breakdown threshold and minimize the time required for conditioning.

  3. Fast thermometry for superconducting rf cavity testing

    SciTech Connect

    Orris, Darryl; Bellantoni, Leo; Carcagno, Ruben H.; Edwards, Helen; Harms, Elvin Robert; Khabiboulline, Timergali N.; Kotelnikov, Sergey; Makulski, Andrzej; Nehring, Roger; Pischalnikov, Yuriy; /Fermilab

    2007-06-01

    Fast readout of strategically placed low heat capacity thermometry can provide valuable information of Superconducting RF (SRF) cavity performance. Such a system has proven very effective for the development and testing of new cavity designs. Recently, several resistance temperature detectors (RTDs) were installed in key regions of interest on a new 9 cell 3.9 GHz SRF cavity with integrated HOM design at FNAL. A data acquisition system was developed to read out these sensors with enough time and temperature resolution to measure temperature changes on the cavity due to heat generated from multipacting or quenching within power pulses. The design and performance of the fast thermometry system will be discussed along with results from tests of the 9 cell 3.9GHz SRF cavity.

  4. Design tool survey. IEA Solar Heating and Cooling - Task 8. Passive and hybrid solar low-energy buildings, Subtask C: design methods

    SciTech Connect

    Rittelmann, P.R.; Ahmed, S.F.

    1985-05-01

    This document presents the results of a survey of design tools conducted as part of Subtask C (Design Methods) of Task VIII of the IAE Solar Heating and Cooling Program. At the start of the task, the participants agreed that it would be useful to identify and characterize the various design tools which existed for predicting the energy performance of passive and hybrid solar low energy buildings. A standard survey form was adopted, and Subtask C representatives from the member countries collected and submitted information on the design tools in use in each country. These responses were compiled into the present survey document.

  5. Radiofrequency Heating Pathways for Gold Nanoparticles

    PubMed Central

    Collins, C. B.; McCoy, R. S.; Ackerson, B. J.; Collins, G. J.

    2015-01-01

    This feature article reviews the thermal dissipation of nanoscopic gold under radiofrequency (RF) irradiation. It also presents previously unpublished data addressing obscure aspects of this phenomenon. While applications in biology motivated initial investigation of RF heating of gold nanoparticles, recent controversy concerning whether thermal effects can be attributed to nanoscopic gold highlight the need to understand the involved mechanism or mechanisms of heating. Both the nature of the particle and the nature of the RF field influence heating. Aspects of nanoparticle chemistry and physics, including the hydrodynamic diameter of the particle, the oxidation state and related magnetism of the core, and the chemical nature of the ligand shell may all strongly influence to what extent a nanoparticle heats in an RF field. Aspects of RF include: power, frequency and antenna designs that emphasize relative strength of magnetic or electric fields, and also influence the extent to which a gold nanoparticle heats in RF. These nanoparticle and RF properties are analysed in the context of three heating mechanisms proposed to explain gold nanoparticle heating in an RF field. This article also makes a critical analysis of the existing literature in the context of the nanoparticle preparations, RF structure, and suggested mechanisms in previously reported experiments. PMID:24962620

  6. RF-driven ion source with a back-streaming electron dump

    DOEpatents

    Kwan, Joe; Ji, Qing

    2014-05-20

    A novel ion source is described having an improved lifetime. The ion source, in one embodiment, is a proton source, including an external RF antenna mounted to an RF window. To prevent backstreaming electrons formed in the beam column from striking the RF window, a back streaming electron dump is provided, which in one embodiment is formed of a cylindrical tube, open at one end to the ion source chamber and capped at its other end by a metal plug. The plug, maintained at the same electrical potential as the source, captures these backstreaming electrons, and thus prevents localized heating of the window, which due to said heating, might otherwise cause window damage.

  7. Unbalanced field RF electron gun

    SciTech Connect

    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.

  8. SEMICONDUCTOR DEVICES: RF CMOS modeling: a novel empirical large-signal model for an RF-MOSFET

    NASA Astrophysics Data System (ADS)

    Lingling, Sun; Binyi, Lü; Jun, Liu; Lei, Chen

    2010-04-01

    A novel empirical model for large-signal modeling of an RF-MOSFET is proposed. The proposed model is validated in the DC, AC, small-signal and large-signal characteristics of a 32-finger nMOSFET fabricated in SMIC's 0.18 μm RF CMOS technology. The power dissipation caused by self-heating is described. Excellent agreement is achieved between simulation and measurement for DC, S-parameters (50 MHz-40 GHz), and power characteristics, which shows that our model is accurate and reliable.

  9. Rf-driver linear colliders

    SciTech Connect

    Wilson, P.B.

    1987-05-01

    The next generation of linear collider after the SLC (Stanford Linear Collider) will probably have an energy in the range 300 GeV-1 TeV per linac. A number of exotic accelerating schemes, such as laser and plasma acceleration, have been proposed for linear colliders of the far future. However, the technology which is most mature and which could lead to a collider in the above energy range in the relatively near future is the rf-driven linac, in which externally produced rf is fed into a more or less conventional metallic accelerating structure. Two basic technologies have been proposed for producing the required high peak rf power: discrete microwave power sources, and various two-beam acceleration schemes in which the rf is produced by a high current driving beam running parallel to the main accelerator. The current status of experimental and analytic work on both the discrete source and the two-beam methods for producing rf is discussed. The implications of beam-beam related effects (luminosity, disruption and beamstrahlung) for the design of rf-driven colliders are also considered.

  10. A survey of membrane oxygenator heat-exchanger integrity testing at cardiac surgery centres in Great Britain and Ireland.

    PubMed

    Carlton, Matthew; Campbell, John

    2013-11-01

    Membrane oxygenator heat exchanger (HE) device failure is reported to be very low for both short- and long-term extracorporeal devices. All oxygenator manufacturers provide instructions for leak testing of their HE devices prior to patient use. In addition to these recommendations, since 2006 at Nottingham University Hospitals (NUH) we have also additionally pressure tested HE devices prior to use. We conducted a national survey of cardiac centers in Great Britain and Ireland to determine the methods undertaken in individual centers for validation of the integrity of HE devices. Furthermore, we also collected information on the routine maintenance techniques utilized within these centers to inhibit microbial growth in the water used in the heater-cooler units (HCUs). In total, 34 responses were collected from the 57 centers performing cardiac surgery, producing a response rate of 60%. Of the responding centers, 71% are adhering to manufacturer's recommended guidelines of circulating the water through the device for 5 minutes. Of these centers, 17% reported detecting a leak between the HE and membrane compartment of the oxygenator. In responding centers, 29% reported using the pressure test technique. In the centers utilizing pressure testing, 60% reported detecting a leak. This survey reports an association of a greater HE leak detection rate using the pressure test technique compared to using water testing in isolation (p = 0.034). We believe the pressure testing method provides the perfusionist with confidence in the integrity of the HE for short- and long-term circulatory support devices prior to use in both elective and emergency situations.

  11. Theory and Practice of Cavity RF Test Systems

    SciTech Connect

    Tom Powers

    2006-08-28

    Over the years Jefferson Lab staff members have performed about 2500 cold cavity tests on about 500 different superconducting cavities. Most of these cavities were later installed in 73 different cryomodules, which were used in three different accelerators. All of the cavities were tested in our vertical test area. About 25% of the cryomodules were tested in our cryomodule test facility and later commissioned in an accelerator. The remainder of the cryomodules were tested and commissioned after they were installed in their respective accelerator. This paper is an overview which should provide a practical background in the RF systems used to test the cavities as well as provide the mathematics necessary to convert the raw pulsed or continuous wave RF signals into useful information such as gradient, quality factor, RF-heat loads and loaded Q?s. Additionally, I will provide the equations necessary for determining the measurement error associated with these values.

  12. Phase modulation in RF tag

    DOEpatents

    Carrender, Curtis Lee; Gilbert, Ronald W.

    2007-02-20

    A radio frequency (RF) communication system employs phase-modulated backscatter signals for RF communication from an RF tag to an interrogator. The interrogator transmits a continuous wave interrogation signal to the RF tag, which based on an information code stored in a memory, phase-modulates the interrogation signal to produce a backscatter response signal that is transmitted back to the interrogator. A phase modulator structure in the RF tag may include a switch coupled between an antenna and a quarter-wavelength stub; and a driver coupled between the memory and a control terminal of the switch. The driver is structured to produce a modulating signal corresponding to the information code, the modulating signal alternately opening and closing the switch to respectively decrease and increase the transmission path taken by the interrogation signal and thereby modulate the phase of the response signal. Alternatively, the phase modulator may include a diode coupled between the antenna and driver. The modulating signal from the driver modulates the capacitance of the diode, which modulates the phase of the response signal reflected by the diode and antenna.

  13. Additive manufacturing of RF absorbers

    NASA Astrophysics Data System (ADS)

    Mills, Matthew S.

    The ability of additive manufacturing techniques to fabricate integrated electromagnetic absorbers tuned for specific radio frequency bands within structural composites allows for unique combinations of mechanical and electromagnetic properties. These composites and films can be used for RF shielding of sensitive electromagnetic components through in-plane and out-of-plane RF absorption. Structural composites are a common building block of many commercial platforms. These platforms may be placed in situations in which there is a need for embedded RF absorbing properties along with structural properties. Instead of adding radar absorbing treatments to the external surface of existing structures, which adds increased size, weight and cost; it could prove to be advantageous to integrate the microwave absorbing properties directly into the composite during the fabrication process. In this thesis, a method based on additive manufacturing techniques of composites structures with prescribed electromagnetic loss, within the frequency range 1 to 26GHz, is presented. This method utilizes screen printing and nScrypt micro dispensing to pattern a carbon based ink onto low loss substrates. The materials chosen for this study will be presented, and the fabrication technique that these materials went through to create RF absorbing structures will be described. The calibration methods used, the modeling of the RF structures, and the applications in which this technology can be utilized will also be presented.

  14. "Politically-Incorrect" Electron Behavior in Low Pressure RF Discharges

    NASA Astrophysics Data System (ADS)

    Godyak, Valery; Kolobov, Vladimir

    1996-10-01

    The main interaction of plasma electrons with electromagnetic fields for bounded plasma of an rf discharge occurs in the vicinity of its boundaries (in the rf sheath of a capacitive rf discharge and in the skin layer of an inductive one). On the other hand, due to plasma inhomogeneity, a dc ambipolar field is always present in the bounded plasma. in low pressure discharges the ambipolar potential well captures low energy electrons within the discharge center while high energy electrons freely overcome the ambipolar potential and reach the plasma boundaries where heating takes place. Being segregated in space, low energy electrons are discriminated from participation in the heating process. When Coulomb interaction between low and high energy electron groups is weak, their temperatures appear to be essentially different ( a low energy peak on the EEDF). In this presentation we present theoretical and experimental evidence of such an apartheid in the low and high energy electron populations of the EEDF in rf discharge and we outline discharge conditions where such abnormal EEDF behavior is possible.

  15. ADX - Advanced Divertor and RF Tokamak Experiment

    NASA Astrophysics Data System (ADS)

    Greenwald, Martin; Labombard, Brian; Bonoli, Paul; Irby, Jim; Terry, Jim; Wallace, Greg; Vieira, Rui; Whyte, Dennis; Wolfe, Steve; Wukitch, Steve; Marmar, Earl

    2015-11-01

    The Advanced Divertor and RF Tokamak Experiment (ADX) is a design concept for a compact high-field tokamak that would address boundary plasma and plasma-material interaction physics challenges whose solution is critical for the viability of magnetic fusion energy. This device would have two crucial missions. First, it would serve as a Divertor Test Tokamak, developing divertor geometries, materials and operational scenarios that could meet the stringent requirements imposed in a fusion power plant. By operating at high field, ADX would address this problem at a level of power loading and other plasma conditions that are essentially identical to those expected in a future reactor. Secondly, ADX would investigate the physics and engineering of high-field-side launch of RF waves for current drive and heating. Efficient current drive is an essential element for achieving steady-state in a practical, power producing fusion device and high-field launch offers the prospect of higher efficiency, better control of the current profile and survivability of the launching structures. ADX would carry out this research in integrated scenarios that simultaneously demonstrate the required boundary regimes consistent with efficient current drive and core performance.

  16. Ion bombardment in RF photoguns

    SciTech Connect

    Pozdeyev,E.; Kayran, D.; Litvinenko, V. N.

    2009-05-04

    A linac-ring eRHIC design requires a high-intensity CW source of polarized electrons. An SRF gun is viable option that can deliver the required beam. Numerical simulations presented elsewhere have shown that ion bombardment can occur in an RF gun, possibly limiting lifetime of a NEA GaAs cathode. In this paper, we analytically solve the equations of motion of ions in an RF gun using the ponderomotive potential of the Rf field. We apply the method to the BNL 1/2-cell SRF photogun and demonstrate that a significant portion of ions produced in the gun can reach the cathode if no special precautions are taken. Also, the paper discusses possible mitigation techniques that can reduce the rate of ion bombardment.

  17. RF deflector system for beamlines

    NASA Astrophysics Data System (ADS)

    Heikkinen, J.; Gustafsson, J.; Kivikoski, M.; Liukkonen, E.; Nieminen, V.

    1999-06-01

    In some in-beam experiments, an adjustment of the time structure of the cyclotron ion beam guided to the desired research target by a beamline is sometimes needed. This situation occurs if, for example, the decay times of the reaction products are too short compared to the period corresponding to the beam frequency. In the accelerator laboratory of the University of Jyväskylä the frequency of the ion pulses hitting the research target is 10-21 MHz depending on the frequency of the acceleration voltage. A RF deflector system was constructed to adjust the ion beam pulse frequency according to the respective requirements. A desired portion of the ion pulses are deflected by feeding a high-amplitude RF-signal between deflecting plates located into the beam line. The specified deflecting voltage amplitude of 10-15 kV is achieved with 1 kW of RF power.

  18. The integrated optic RF spectrum analyzer

    NASA Technical Reports Server (NTRS)

    Pedinoff, M. E.; Ranganath, T. R.; Joseph, T. R.; Lee, J. Y.

    1981-01-01

    The results of measurements made on a fully integrated optic RF spectrum analyzer (IOSA) are reported. The performance of the device acousto-optic bandwidth, single-tone RF resolution, two-tone RF resolution, single-tone dynamic range, two-tone dynamic range, and single-tone RF response are presented. The device parameters that control device performance are analyzed. These results demonstrate the viability of the IOSA for real time spectrum analysis of pulsed and CW RF signals. Improvements of RF bandwidth resolution can be obtained by the use of larger collimated optical beams which requires larger optical lens elements, and hence, larger crystals.

  19. Plasma rotation induced by RF

    SciTech Connect

    Chan, V. S.; Chiu, S. C.; Lin-Liu, Y. R. [General Atomics, P.O. Box 85608, San Diego, California 92186-5698; Omelchenko, Y. A. [General Atomics, P.O. Box 85608, San Diego, California 92186-5698

    1999-09-20

    Plasma rotation has many beneficial effects on tokamak operation including stabilization of MHD and microturbulence to improve the beta limit and confinement. Contrary to present-day tokamaks, neutral beams may not be effective in driving rotation in fusion reactors; hence the investigation of radiofrequency (RF) induced plasma rotation is of great interest and potential importance. This paper reviews the experimental results of RF induced rotation and possible physical mechanisms, suggested by theories, to explain the observations. This subject is only in the infancy of its research and many challenging issues remained to be understood and resolved. (c) 1999 American Institute of Physics.

  20. RF-source resistance meters

    NASA Technical Reports Server (NTRS)

    Oakley, E. C. (Inventor)

    1973-01-01

    Several embodiments of RF source resistance measuring devices are disclosed. Common to all embodiments in the feature of the inclusion of at least one variable resistor, and a peak readout meter. In one embodiment, two ganged unloaded potentiometers are employed while another embodiment comprises an automaticnulling RF power bridge circuit with a variable rather than a fixed bridge reference resistance. A third embodiment comprises a calorimeter with a varible rather than a fixed resistor, while in another embodiment attenuator pads with variable resistors are employed.

  1. Nuclear magnetic resonance apparatus having semitoroidal rf coil for use in topical NMR and NMR imaging

    DOEpatents

    Fukushima, Eiichi; Roeder, Stephen B. W.; Assink, Roger A.; Gibson, Atholl A. V.

    1986-01-01

    An improved nuclear magnetic resonance (NMR) apparatus for use in topical magnetic resonance (TMR) spectroscopy and other remote sensing NMR applications includes a semitoroidal radio-frequency (rf) coil. The semitoroidal rf coil produces an effective alternating magnetic field at a distance from the poles of the coil, so as to enable NMR measurements to be taken from selected regions inside an object, particularly including human and other living subjects. The semitoroidal rf coil is relatively insensitive to magnetic interference from metallic objects located behind the coil, thereby rendering the coil particularly suited for use in both conventional and superconducting NMR magnets. The semitoroidal NMR coil can be constructed so that it emits little or no excess rf electric field associated with the rf magnetic field, thus avoiding adverse effects due to dielectric heating of the sample or to any other interaction of the electric field with the sample.

  2. Ion extraction from a saddle antenna RF surface plasma source

    SciTech Connect

    Dudnikov, V. Johnson, R. P.; Han, B.; Murray, S.; Pennisi, T.; Piller, C.; Santana, M.; Stockli, M.; Welton, R.; Breitschopf, J.; Dudnikova, G.

    2015-04-08

    Existing RF Surface Plasma Sources (SPS) for accelerators have specific efficiencies for H{sup +} and H{sup −} ion generation around 3 to 5 mA/cm{sup 2} per kW, where about 50 kW of RF power is typically needed for 50 mA beam current production. The Saddle Antenna (SA) SPS described here was developed to improve H{sup −} ion production efficiency and SPS reliability and availability. At low RF power, the efficiency of positive ion generation in the plasma has been improved to 200 mA/cm{sup 2} per kW of RF power at 13.56 MHz. Initial cesiation of the SPS was performed by heating cesium chromate cartridges by discharge as was done in the very first versions of the SPS. A small oven to decompose cesium compounds and alloys was developed and tested. After cesiation, the current of negative ions to the collector was increased from 1 mA to 10 mA with RF power ∼1.5 kW in the plasma (6 mm diameter emission aperture) and up to 30 mA with ∼4 kW RF power in the plasma and 250 Gauss longitudinal magnetic field. The ratio of electron current to negative ion current was improved from 30 to 2. Stable generation of H{sup −} beam without intensity degradation was demonstrated in the AlN discharge chamber for a long time at high discharge power in an RF SPS with an external antenna. Continuous wave (CW) operation of the SA SPS has been tested on the small test stand. The general design of the CW SA SPS is based on the pulsed version. Some modifications were made to improve the cooling and cesiation stability. The extracted collector current can be increased significantly by optimizing the longitudinal magnetic field in the discharge chamber. CW operation with negative ion extraction was tested with RF power up to 1.8 kW from the generator (∼1.2 kW in the plasma) with production up to Ic=7 mA. Long term operation was tested with 1.2 kW from the RF generator (∼0.8 kW in the plasma) with production of Ic=5 mA, Iex ∼15 mA (Uex=8 kV, Uc=14 kV)

  3. Cryostat for testing RF power couplers

    SciTech Connect

    Kuchnir, M.; Champion, M.S.; Koepke, K.P.; Misek, J.R.

    1996-03-01

    Similar to the power leads of accelerator superconducting magnets, the power couplers of accelerator superconducting cavities are components that link room temperature to superfluid helium temperature for the purpose of energy transfer. Instead of conducting kiloamperes of current they guide megawatts of RF power between those two temperatures. In this paper we describe a cryostat designed for testing the performance of these components and measuring their heat loads. A special feature of this cryostat is its minimum liquid inventory that considerably simplifies safety related requirements. This cryostat is part of a Fermilab facility contributing to the international collaboration working on TESLA (TeV Electron Superconducting Linear Accelerator). This facility is now operational and we will be presenting specifications as well as performance data on the cryostat as well as the first pair of power couplers tested with it.

  4. Proposed RF Breakdown Studies at the AWA

    SciTech Connect

    Antipov, S.; Conde, M.; Gai, W.; Power, J.G.; Spentzouris, L.; Yusof, Z.; Dolgashev, V.; /SLAC

    2007-03-21

    A study of breakdown mechanism has been initiated at the Argonne Wakefield Accelerator (AWA). Breakdown may include several factors such as local field enhancement, explosive electron emission, Ohmic heating, tensile stress produced by electric field, and others. The AWA is building a dedicated facility to test various models for breakdown mechanisms and to determine the roles of different factors in the breakdown. We plan to trigger breakdown events with a high-powered laser at various wavelengths (IR to UV) to determine the role of explosive electron emission in the breakdown process. Another experimental idea follows from the recent work on a Schottky-enabled photoemission in an RF photoinjector [1] that allows us to determine in situ the field enhancement factor on a cathode surface. Monitoring the field enhancement factor before and after the breakdown can shed some light on a number of observations such as the crater formation process.

  5. Negative ion source with external RF antenna

    DOEpatents

    Leung, Ka-Ngo; Hahto, Sami K.; Hahto, Sari T.

    2007-02-13

    A radio frequency (RF) driven plasma ion source has an external RF antenna, i.e. the RF antenna is positioned outside the plasma generating chamber rather than inside. The RF antenna is typically formed of a small diameter metal tube coated with an insulator. An external RF antenna assembly is used to mount the external RF antenna to the ion source. The RF antenna tubing is wound around the external RF antenna assembly to form a coil. The external RF antenna assembly is formed of a material, e.g. quartz, which is essentially transparent to the RF waves. The external RF antenna assembly is attached to and forms a part of the plasma source chamber so that the RF waves emitted by the RF antenna enter into the inside of the plasma chamber and ionize a gas contained therein. The plasma ion source is typically a multi-cusp ion source. A converter can be included in the ion source to produce negative ions.

  6. NCSX Plasma Heating Methods

    SciTech Connect

    Kugel, H. W.; Spong, D.; Majeski, R.; Zarnstorff, M.

    2008-01-18

    The National Compact Stellarator Experiment (NCSX) has been designed to accommodate a variety of heating systems, including ohmic heating, neutral beam injection, and radio-frequency (rf). Neutral beams will provide one of the primary heating methods for NCSX. In addition to plasma heating, neutral beams are also expected to provide a means for external control over the level of toroidal plasma rotation velocity and its profile. The experimental plan requires 3 MW of 50-keV balanced neutral beam tangential injection with pulse lengths of 500 ms for initial experiments, to be upgradeable to pulse lengths of 1.5 s. Subsequent upgrades will add 3MW of neutral beam injection (NBI). This paper discusses the NCSX NBI requirements and design issues and shows how these are provided by the candidate PBX-M NBI system. In addition, estimations are given for beam heating efficiencies, scaling of heating efficiency with machine size and magnetic field level, parameter studies of the optimum beam injection tangency radius and toroidal injection location, and loss patterns of beam ions on the vacuum chamber wall to assist placement of wall armor and for minimizing the generation of impurities by the energetic beam ions. Finally, subsequent upgrades could add an additional 6 MW of rf heating by mode conversion ion Bernstein wave (MCIBW) heating, and if desired as possible future upgrades, the design also will accommodate high-harmonic fast-wave and electron cyclotron heating. The initial MCIBW heating technique and the design of the rf system lend themselves to current drive, so if current drive became desirable for any reason, only minor modifications to the heating system described here would be needed. The rf system will also be capable of localized ion heating (bulk or tail), and possiblyIBW-generated sheared flows.

  7. Electrical characterization of rf plasmas

    SciTech Connect

    Miller, P.A.

    1991-08-01

    Radio-frequency (rf) electrical sources are commonly used to generate plasmas for processing of industrial materials and for related experimental work. Published descriptions of such plasmas usually include generator-power measurements, and occasionally include plasma dc-bias measurements. One or both of these quantitites are also used in industrial feedback ccontrol systems for setpoint regulation. Recent work at Sandia an elsewhere with an experimental rf discharge device (the GEC RF Reference Cell'') has shown that power and dc-bias levels are often insufficient information for specifying the state of the plasma. The plasma can have nonlinear electrical characteristics that cause harmonic generation, and the harmonic levels can depend sensitively on the impedance of the external circuitry at harmonic frequencies. Even though the harmonics may be low in amplitude, they can be directly related to large changes in plasma power and to changes in optical emission from the plasma. Consequently, in order for a worker to truly master the plasma-generation process, it is necessary to understand, measure, and control electrical characteristics of the plamsa. In this paper we describe technique that have been developed from work with the Reference Cell for making electrical measurements on rf plasmas, and we describe surprising observations of harmonic behavior. 10 refs., 4 figs.

  8. Automatic calorimetry system monitors RF power

    NASA Technical Reports Server (NTRS)

    Harness, B. W.; Heiberger, E. C.

    1969-01-01

    Calorimetry system monitors the average power dissipated in a high power RF transmitter. Sensors measure the change in temperature and the flow rate of the coolant, while a multiplier computes the power dissipated in the RF load.

  9. Simulation of synchrotron motion with rf noise

    SciTech Connect

    Leemann, B.T.; Forest, E.; Chattopadhyay, S.

    1986-08-01

    The theoretical formulation is described that is behind an algorithm for synchrotron phase-space tracking with rf noise and some preliminary simulation results of bunch diffusion under rf noise obtained by actual tracking.

  10. The role of natural E-region plasma turbulence in the enhanced absorption of HF radio waves in the auroral ionosphere:Implications for RF heating of the auroral electrojet

    NASA Astrophysics Data System (ADS)

    Robinson, T. R.

    1994-04-01

    Physical processes which affect the absorption of radio waves passing through the auroral E-region when Farley-Buneman irregularities are present are examined. In particular, the question of whether or not it is legitimate to include the anomalous wave-enhanced collision frequency, which has been used successfully to account for the heating effects of Farley-Buneman waves in the auroral E-region, in the usual expression for the radio-wave absorption coefficient is addressed. Effects also considered are those due to wave coupling between electromagnetic waves and high-frequency electrostatic waves in the presence of Farley-Buneman irregularities. The implications for radio-wave heating of the auroral electrojet of these processes are also discussed. In particular, a new theoretical model for calculating the effects of high-power radio-wave heating on the electron temperature in an electrojet containing Farley-Buneman turbulence is presented.

  11. Evaluation of thermal effects due to back-streaming electrons in the IAE RF gun

    NASA Astrophysics Data System (ADS)

    Kii, Toshiteru; Masuda, Kai; Amazaki, Satoshi; Horii, Tomohiro; Toku, Hisayuki; Yoshikawa, Kiyoshi; Ohgaki, Hideaki; Yamazaki, Tetsuo

    2002-05-01

    Back-streaming electrons in thermionic RF guns give a serious thermal effect to a cathode. In this study, the back-streaming beam power onto a thermionic cathode of the IAE RF gun was evaluated quantitatively by using an infrared radiation thermometer. Time evolutions of cathode surface temperature during RF macro-pulse were also calculated by using a simple 1-dimensional heat conduction model and results of a 2-dimensional particle simulation for several methods expected to reduce back-bombardment effect.

  12. RF digital-to-analog converter

    DOEpatents

    Conway, P.H.; Yu, D.U.L.

    1995-02-28

    A digital-to-analog converter is disclosed for producing an RF output signal proportional to a digital input word of N bits from an RF reference input, N being an integer greater or equal to 2. The converter comprises a plurality of power splitters, power combiners and a plurality of mixers or RF switches connected in a predetermined configuration. 18 figs.

  13. RF digital-to-analog converter

    DOEpatents

    Conway, Patrick H.; Yu, David U. L.

    1995-01-01

    A digital-to analogue converter for producing an RF output signal proportional to a digital input word of N bits from an RF reference input, N being an integer greater or equal to 2. The converter comprises a plurality of power splitters, power combiners and a plurality of mixers or RF switches connected in a predetermined configuration.

  14. Computer modeling of hyperthermia temperature distributions produced by hybrid RF/US phased arrays

    NASA Astrophysics Data System (ADS)

    Wu, Liyong; Zeng, Xiaozheng; Chen, Duo; McGough, Robert J.

    2006-05-01

    Simulation studies of hyperthermia as an adjuvant treatment for locally advanced breast cancer (LABC) show that temperature distributions are significantly improved with hybrid devices that combine ultrasound (US) and radio-frequency (RF) electromagnetic phased arrays. Ultrasound phased arrays, which generate relatively small focal spots in deep targets, are limited by intervening tissue heating in 60-minute hyperthermia treatments of large LABC tumors. In contrast RF phased arrays are regional heating devices with limited penetration depths. This combination offsets the drawbacks of each modality while offering multiple opportunities for optimization in LABC tumors. One optimization strategy partitions the tumor into two regions that are targeted individually by each modality. This approach targets the portion of the tumor proximal to the RF applicator and/or the skin surface with the RF component, and the US component delivers heat to the tumor in regions that the RF fails to reach. This heating strategy includes US contributions from focal points and intervening tissue heating within the tumor target. The resulting temperature distribution achieves higher, more uniform temperatures within the tumor target than either modality applied individually.

  15. RF-Thermal-Structural Analysis of a Waveguide Higher Order Mode Absorber

    SciTech Connect

    G. Cheng; E. F. Daly; R. A. Rimmer; M. Stirbet; L. Vogel; H. Wang; K. M. Wilson

    2007-07-03

    For an ongoing high current cryomodule project, a total of 5 higher order mode (HOM) absorbers are required per cavity. The load is designed to absorb Radio Frequency (RF) heat induced by HOMs in a 748.5MHz cavity. Each load is targeted at a 4 kW dissipation capability. Water cooling is employed to remove the heat generated in ceramic tiles and by surface losses on the waveguide walls. A sequentially coupled RF-thermal-structural analysis was developed in ANSYS to optimize the HOM load design. Frequency-dependent dielectric material properties measured from samples and RF power spectrum calculated by the beam-cavity interaction codes were considered. The coupled field analysis capability of ANSYS avoided mapping of results between separate RF and thermal/structural simulation codes. For verification purposes, RF results obtained from ANSYS were compared to those from MAFIA, HFSS, and Microwave Studio. Good agreement was reached and this confirms that multiple-field coupled analysis is a desirable choice in analysis of HOM loads. Similar analysis could be performed on other particle accelerator components where distributed RF heating and surface current induced losses are inevitable.

  16. Plasma-materials interactions during rf experiments in tokamaks

    SciTech Connect

    Cohen, S.A.; Bernabei, S.; Budny, R.; Chu, T.K.; Colestock, P.; Hinnov, E.; Hooke, W.; Hosea, J.; Hwang, D.; Jobes, F.

    1984-09-01

    Plasma-materials interactions studied in recent ICRF heating and lower hybrid current drive experiments are reviewed. The microscopic processes responsible for impurity generation are discussed. In ICRF experiments, improvements in machine operation and in antenna and feedthrough design have allowed efficient plasma heating at RF powers up to 3 MW. No significant loss of energy from the plasma core due to impurity radiation occurs. Lower hybrid current drive results in the generation and maintenance of hundreds of kiloamperes of plasma current carried by suprathermal electrons. The loss of these electrons and their role in impurity generation are assessed. Methods to avoid this problem are evaluated.

  17. Study of AC/RF properties of SRF ingot niobium

    SciTech Connect

    Dhakal, Pashupati; Tsindlekht, Menachem I; Genkin, Valery M; Ciovati, Gianluigi; Myneni, Ganapati Rao

    2013-09-01

    In an attempt to correlate the performance of superconducting radiofrequency cavities made of niobium with the superconducting properties, we present the results of the magnetization and ac susceptibility of the niobium used in the superconducting radiofrequency cavity fabrication. The samples were subjected to buffer chemical polishing (BCP) surface and high temperature heat treatments, typically applied to the cavities fabrications. The analysis of the results show the different surface and bulk ac conductivity for the samples subjected to BCP and heat treatment. Furthermore, the RF surface impedance is measured on the sample using a TE011 microwave cavity for a comparison to the low frequency measurements.

  18. A thermodynamical analysis of rf current drive with fast electrons

    NASA Astrophysics Data System (ADS)

    Bizarro, João P. S.

    2015-08-01

    The problem of rf current drive (CD) by pushing fast electrons with high-parallel-phase-velocity waves, such as lower-hybrid (LH) or electron-cyclotron (EC) waves, is revisited using the first and second laws, the former to retrieve the well-known one-dimensional (1D) steady-state CD efficiency, and the latter to calculate a lower bound for the rate of entropy production when approaching steady state. The laws of thermodynamics are written in a form that explicitly takes care of frictional dissipation and are thus applied to a population of fast electrons evolving under the influence of a dc electric field, rf waves, and collisions while in contact with a thermal, Maxwellian reservoir with a well-defined temperature. Besides the laws of macroscopic thermodynamics, there is recourse to basic elements of kinetic theory only, being assumed a residual dc electric field and a strong rf drive, capable of sustaining in the resonant region, where waves interact with electrons, a raised fast-electron tail distribution, which becomes an essentially flat plateau in the case of the 1D theory for LHCD. Within the 1D model, particularly suited for LHCD as it solely retains fast-electron dynamics in velocity space parallel to the ambient magnetic field, an H theorem for rf CD is also derived, which is written in different forms, and additional physics is recovered, such as the synergy between the dc and rf power sources, including the rf-induced hot conductivity, as well as the equation for electron-bulk heating. As much as possible 1D results are extended to 2D, to account for ECCD by also considering fast-electron velocity-space dynamics in the direction perpendicular to the magnetic field, which leads to a detailed discussion on how the definition of an rf-induced conductivity may depend on whether one works at constant rf current or power. Moreover, working out the collisional dissipated power and entropy-production rate written in terms of the fast-electron distribution, it

  19. A thermodynamical analysis of rf current drive with fast electrons

    SciTech Connect

    Bizarro, João P. S.

    2015-08-15

    The problem of rf current drive (CD) by pushing fast electrons with high-parallel-phase-velocity waves, such as lower-hybrid (LH) or electron-cyclotron (EC) waves, is revisited using the first and second laws, the former to retrieve the well-known one-dimensional (1D) steady-state CD efficiency, and the latter to calculate a lower bound for the rate of entropy production when approaching steady state. The laws of thermodynamics are written in a form that explicitly takes care of frictional dissipation and are thus applied to a population of fast electrons evolving under the influence of a dc electric field, rf waves, and collisions while in contact with a thermal, Maxwellian reservoir with a well-defined temperature. Besides the laws of macroscopic thermodynamics, there is recourse to basic elements of kinetic theory only, being assumed a residual dc electric field and a strong rf drive, capable of sustaining in the resonant region, where waves interact with electrons, a raised fast-electron tail distribution, which becomes an essentially flat plateau in the case of the 1D theory for LHCD. Within the 1D model, particularly suited for LHCD as it solely retains fast-electron dynamics in velocity space parallel to the ambient magnetic field, an H theorem for rf CD is also derived, which is written in different forms, and additional physics is recovered, such as the synergy between the dc and rf power sources, including the rf-induced hot conductivity, as well as the equation for electron-bulk heating. As much as possible 1D results are extended to 2D, to account for ECCD by also considering fast-electron velocity-space dynamics in the direction perpendicular to the magnetic field, which leads to a detailed discussion on how the definition of an rf-induced conductivity may depend on whether one works at constant rf current or power. Moreover, working out the collisional dissipated power and entropy-production rate written in terms of the fast-electron distribution, it

  20. High gradient RF breakdown studies

    NASA Astrophysics Data System (ADS)

    Laurent, Lisa Leanne

    Higher accelerating gradients are required by future demands for TeV electron linear colliders. With higher energy comes the challenge of handling stronger electromagnetic fields in the accelerator structures and in the microwave sources that supply the power. A limit on the maximum field gradient is imposed by rf electrical breakdown. Investigating methods to achieve higher gradients and to better understand the mechanisms involved in the rf breakdown process has been the focal point of this study. A systematic series of rf breakdown experiments have been conducted at Stanford Linear Accelerator Center utilizing a transmission cavity operating in the TM020 mode. A procedure was developed to examine the high gradient section of the cavity in an electron microscope. The results have revealed that breakdown asymmetry exists between opposing high gradient surfaces. During breakdown, a plasma formation is detected localized near the surface with no visible evidence of an arc traversing the gap. These findings support the theory that high frequency rf breakdown is a single surface phenomenon. Other results from this study have shown that breakdown can occur at relatively low voltages when surface irregularities exist and along grain boundaries. A series of steps have been developed through this study that have significantly reduced the number of breakdowns that occur along grain boundaries. Testing under various vacuum conditions (10-11--10 -5 Torr) have revealed that while the breakdown threshold remained the same, the field emitted current density increased by almost two orders of magnitude. This suggests that the total field emitted current density is not the critical parameter in the initiation of high frequency vacuum breakdown. In the course of this study, microparticles were carefully tracked before and after rf processing. The outcome of this research suggests that expensive cleanroom facilities may not offer any advantage over practicing good cleaning and

  1. Superfluid helium cryogenic systems for superconducting RF cavities at KEK

    SciTech Connect

    Nakai, H.; Hara, K.; Honma, T.; Hosoyama, K.; Kojima, Y.; Nakanishi, K.; Kanekiyo, T.; Morita, S.

    2014-01-29

    Recent accelerator projects at KEK, such as the Superconducting RF Test Facility (STF) for R and D of the International Linear Collider (ILC) project and the compact Energy Recovery Linac (cERL), employ superconducting RF cavities made of pure niobium, which can generate high gradient acceleration field. Since the operation temperature of these cavities is selected to be 2 K, we have developed two 2 K superfluid helium cryogenic systems for stable operation of superconducting RF cavities for each of STF and cERL. These two 2 K superfluid helium cryogenic systems are identical in principle. Since the operation mode of the cavities is different for STF and cERL, i.e. the pulse mode for STF and the continuous wave mode for cERL, the heat loads from the cavities are quite different. The 2 K superfluid helium cryogenic systems mainly consists of ordinary helium liquefiers/refrigerators, 2 K refrigerator cold boxes, helium gas pumping systems and high-performance transfer lines. The 2 K refrigerators and the high-performance transfer lines are designed by KEK. Some superconducting RF cavity cryomodules have been already connected to the 2 K superfluid helium cryogenic systems for STF and cERL respectively, and cooled down to 2 K successfully.

  2. Mitigating impact of rectified RF sheath potential on the ELMs

    NASA Astrophysics Data System (ADS)

    Gui, Bin; Xu, Xueqiao; Xia, Tianyang

    2014-10-01

    Here we report on the BOUT++ simulation results for the mitigating impact of rectified RF sheath potential on the peeling-ballooning modes. The limiter and the RF wave antenna are placed at the outer middle plane in the scrape-off-layer (SOL) in shift-circle geometry. The external shear flow is induced by the limiter and the RF wave. Besides this, the sheath boundary conditions are imposed on the perturbed potential and parallel current. From the three-field simulations, it is found that the energy loss is suppressed by the external shear flow in the nonlinear phase. The external shear flow due to the RF wave leads to a broad turbulence spectrum. The wider spectrum leads to a weaker turbulence transport and results in a smaller energy loss. The perturbed electric potential and the parallel current near the sheath region are also suppressed locally due to the sheath boundary condition. Based on this work, this effect of limiter will also be applied in six-field which includes more physics effects. The effect of sheath boundary conditions on the thermal conductivities and heat flux will be studied. This work was performed for USDOE by LLNL under DE-AC52-07NA27344, LLNL LDRD project 12-ERD-022 and the China Natural Science Foundation under Contract No. 10721505. LLNL-ABS-657008.

  3. RF power coupling for the CSNS DTL

    NASA Astrophysics Data System (ADS)

    Liu, Hua-Chang; Peng, Jun; Yin, Xue-Jun; Ouyang, Hua-Fu; Fu, Shi-Nian

    2011-01-01

    The China Spallation Neutron Source (CSNS) drift tube linac (DTL) consists of four tanks and each tank is fed by a 2.5 MW klystron. Accurate predication of RF coupling between the RF cavity and ports is very important for DTL RF coupler design. An iris-type coupler is chosen to couple the RF power to the DTL accelerating cavity. The physical design of the DTL coupler and the calculations of RF coupling between the cavity and coupler are carried out. The results from the numerical simulations are in excellent agreement with the analytical results.

  4. Taming Magnetically Confined Plasmas with RF Waves: A Historical Perspective

    NASA Astrophysics Data System (ADS)

    Porkolab, Miklos

    2009-11-01

    Heating and profile control by RF waves in magnetic fusion experiments has led to the development of a new area of physics, namely wave propagation and absorption in high temperature plasmas in complex magnetic field geometries. In addition, the development of high power microwave sources as well as novel antenna structures capable of handling high RF powers has also been necessary. In this talk I shall summarize the historical progression of relevant results in three frequency regimes, namely the ion cyclotron range of frequencies (ICRF), the electron cyclotron frequency and its harmonics (ECRH), and the lower hybrid frequency range (LHRF). In the ICRF regime breakthrough heating results were obtained in the 1980s in tokamaks with good confinement of energetic ions, such as PLT, TFTR and JET. In the period of late 1970s to mid 1980s the theory of RF current drive (LHCD, ECCD and that of fast wave, or FWCD) was developed. Soon thereafter efficient lower hybrid current drive was demonstrated in tokamak experiments such as Versator II, Alcator--C and PLT, and later JT60-U, Tore-Supra and JET. High harmonic FWCD has been also demonstrated on DIII-D and NSTX. Long pulse multi-MW LHCD experiments are now in preparation on the new superconducting tokamaks EAST (China) and K-STAR (Korea). ECRH results in the 1980s and beyond progressed rapidly with the development of gyrotron sources at the MW level and subsequently efficient heating and current drive was demonstrated on DIII-D, Asdex-U, JT-60U and TCV, including the stabilization of neoclassical tearing modes. Recent gyrotron tube development at the MW level at 170 GHz ensures the availability of ECH and ECCD on ITER. Finally, new results on RF induced transport phenomena have been discovered, such as enhanced plasma rotation and flow drive that hold promise for optimizing ITER performance.

  5. Double rf system for bunch shortening

    SciTech Connect

    Chin, Yong Ho.

    1990-11-01

    It was suggested by Zisman that the combination of the two systems (double rf system) may be more effective to shorten a bunch, compromising between the desirable and the undesirable effects mentioned above. In this paper, we demonstrate that a double rf system is, in fact, quite effective in optimizing the rf performance. The parameters used are explained, and some handy formulae for bunch parameters are derived. We consider an example of bunch shortening by adding a higher-harmonic rf system to the main rf system. The parameters of the main rf system are unchanged. The double rf system, however, can be used for another purpose. Namely, the original bunch length can be obtained with a main rf voltage substantially lower than for a single rf system without necessitating a high-power source for the higher-harmonic cavities. Using a double rf system, the momentum acceptance remains large enough for ample beam lifetime. Moreover, the increase in nonlinearity of the rf waveform increases the synchrotron tune spread, which potentially helps a beam to be stabilized against longitudinal coupled-bunch instabilities. We will show some examples of this application. We discuss the choice of the higher-harmonic frequency.

  6. Recent Advancements of RF Guns

    NASA Astrophysics Data System (ADS)

    Faillace, Luigi

    High-brightness, high-current electron beams are the main requirement for fourth generation light sources such as free-electron lasers (FELs), energy recovery Linacs (ERLs) and high-energy linear colliders. The most successful device for producing such beams is the Radio-Frequency (RF) photoinjector that has been undergoing a constant evolution over the past nearly 30 years towards the production of ever-lower beam emittances and higher currents. The on-going progress in the technology of higher quality materials as well as the enhanced quality of laser pulse shaping have allowed huge improvements in the generation of higher-quality electron beams. Here, it is presented an overview of recent advancements and future perspectives of RF photoinjectors for a fifth generation light source.

  7. Noninductive RF startup in CDX-U

    NASA Astrophysics Data System (ADS)

    Jones, B.; Majeski, R.; Efthimion, P.; Kaita, R.; Menard, J.; Munsat, T.; Takase, Y.

    1998-11-01

    For the spherical torus (ST) to prove viable as a reactor, it will be necessary to devise techniques for noninductive plasma startup. Initial studies of noninductive plasma initiation have been performed on CDX-U, using the 100 kW high harmonic fast wave (HHFW) system in combination with the 1 kW 2.45 GHz electron cyclotron heating system used for breakdown. Modest density (ne ~ 10^12 cm-3), low temperature (5 eV) plasmas were formed, but the density profile was peaked far off-axis, very near the HHFW antenna. High neutral fill pressures were also required. In upcoming experiments, up to 500 kW of low frequency RF power will utilized for heating and noninductive current drive in the mode conversion regime in a target noninductive plasma formed by a combination of 5.6 and 14 GHz ECH (40 kW total). Modeling will be presented which indicates that startup to plasma currents of 60 kA is feasible with this system.

  8. Low jitter RF distribution system

    DOEpatents

    Wilcox, Russell; Doolittle, Lawrence; Huang, Gang

    2012-09-18

    A timing signal distribution system includes an optical frequency stabilized laser signal amplitude modulated at an rf frequency. A transmitter box transmits a first portion of the laser signal and receive a modified optical signal, and outputs a second portion of the laser signal and a portion of the modified optical signal. A first optical fiber carries the first laser signal portion and the modified optical signal, and a second optical fiber carries the second portion of the laser signal and the returned modified optical signal. A receiver box receives the first laser signal portion, shifts the frequency of the first laser signal portion outputs the modified optical signal, and outputs an electrical signal on the basis of the laser signal. A detector at the end of the second optical fiber outputs a signal based on the modified optical signal. An optical delay sensing circuit outputs a data signal based on the detected modified optical signal. An rf phase detect and correct signal circuit outputs a signal corresponding to a phase stabilized rf signal based on the data signal and the frequency received from the receiver box.

  9. Rf System for the NLCTA

    SciTech Connect

    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.; /SLAC

    2011-08-26

    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.

  10. Rf System for the NLCTA

    NASA Astrophysics Data System (ADS)

    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, T. 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.

    1997-05-01

    This paper describes an X-Band rf system for the Next Linear Accelerator 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, or damped and detuned, accelerator sections powered in pairs. The rf power generation, compression, delivery, distribution and measurement systems consist of klystrons, SLED-II 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. The correct phasing between two 0.9 m accelerator sections is obtained by properly setting the sections and adjusting two squeeze type phase shifters. Also, bunch phase and bunch length can be monitored by special microwave cavities and measurement systems. The design, fabrication, microwave measurement, calibration, and operation for above sub-systems and their components will be presented.

  11. ICR Heating in Ion Separation Systems

    SciTech Connect

    Timofeev, A.V.

    2005-12-15

    A systematic procedure for analyzing the physical processes that govern ICR heating in systems for ion separation is developed. The procedure is based on an analytic model of an rf antenna generating rf fields within a plasma column in a magnetic field and includes such issues as the calculation of rf fields, examination of the ICR interaction of ions with these fields, and determination of the distribution function of the ion flow at the exit from the ICR heating system. It is shown that, even in ICR heating systems with easily achievable parameter values, ions with appreciably different masses can be efficiently separated by energy.

  12. Transport modeling of the ORNL high intensity linear RF plasma source

    NASA Astrophysics Data System (ADS)

    Owen, L. W.; Peng, Y. K. M.; Canik, J. M.; Goulding, R. H.; Bonnin, X.

    2010-11-01

    Recent progress in the electrode-less helicon hydrogenic plasma sourceootnotetextR.H. Goulding, et al., Proc. 18th Conf on RF Power in Plasmas, Gent, Belgium, June, 2009. have motivated the development at ORNL of an RF-plasma source that magnetically links a helicon to a mirror cell in which the plasma is heated by EBW, ICH and whistler waves. The <4m long plasma column further includes a parallel transport region connected to a pumped target plate. Such a source is modeled at three levels using: a two-point model, a 1D-parallel Braginski's fluid model in which the plasma sources/sinks are computed using the kinetic Monte Carlo neutrals code DEGAS, and the 2D SOLPS code. The required source plasma parameters to achieve certain target plasma parameters, particularly at high plasma heat and particle fluxes, are found to be sensitive to the plasma and neutrals parameters in the helicon and RF mirror cells, the effective heating via various RF techniques, the plasma and neutrals boundary conditions at the target plates and around the RF-plasma heating zones, and the pumped reservoirs with partial backflow of thermal molecules. New results of this investigation will be reported.

  13. A novel multi-actuation CMOS RF MEMS switch

    NASA Astrophysics Data System (ADS)

    Lee, Chiung-I.; Ko, Chih-Hsiang; Huang, Tsun-Che

    2008-12-01

    This paper demonstrates a capacitive shunt type RF MEMS switch, which is actuated by electro-thermal actuator and electrostatic actuator at the same time, and than latching the switching status by electrostatic force only. Since thermal actuators need relative low voltage compare to electrostatic actuators, and electrostatic force needs almost no power to maintain the switching status, the benefits of the mechanism are very low actuation voltage and low power consumption. Moreover, the RF MEMS switch has considered issues for integrated circuit compatible in design phase. So the switch is fabricated by a standard 0.35um 2P4M CMOS process and uses wet etching and dry etching technologies for postprocess. This compatible ability is important because the RF characteristics are not only related to the device itself. If a packaged RF switch and a packaged IC wired together, the parasitic capacitance will cause the problem for optimization. The structure of the switch consists of a set of CPW transmission lines and a suspended membrane. The CPW lines and the membrane are in metal layers of CMOS process. Besides, the electro-thermal actuators are designed by polysilicon layer of the CMOS process. So the RF switch is only CMOS process layers needed for both electro-thermal and electrostatic actuations in switch. The thermal actuator is composed of a three-dimensional membrane and two heaters. The membrane is a stacked step structure including two metal layers in CMOS process, and heat is generated by poly silicon resistors near the anchors of membrane. Measured results show that the actuation voltage of the switch is under 7V for electro-thermal added electrostatic actuation.

  14. Low Cost RF Amplifier for Community TV

    NASA Astrophysics Data System (ADS)

    Ch, Syafaruddin; Sasongko, Sudi Mariyanto Al; Made Budi Suksmadana, I.; Mustiko Okta Muvianto, Cahyo; Ariessaputra, Suthami

    2016-01-01

    he capability of television to deliver audio video makes this media become the most effective method to spread information. This paper presents an experiment of RF amplifier design having low-cost design and providing sufficient RF power particularly for community television. The RF amplifier consists of two stages of amplifier. The first stage amplifier was used to leverage output of TV modulator from 11dBm to enable to drive next stage amplifier. CAD simulation and fabrication were run to reach optimum RF amplifier design circuit. The associated circuit was made by determining stability circle, stability gain, and matching impedance. Hence, the average power of first stage RF amplifier was 24.68dBm achieved. The second stage used RF modules which was ready match to 50 ohm for both input and output port. The experiment results show that the RF amplifier may operate at frequency ranging from 174 to 230MHz. The average output power of the 2nd stage amplifier was 33.38 Watt with the overall gain of 20.54dB. The proposed RF amplifier is a cheap way to have a stable RF amplifier for community TV. The total budget for the designed RF amplifier is only a 1/5 compared to local design of final TV amplifier.

  15. RF Processing Experience with the GTF Prototype RF Gun

    SciTech Connect

    Schmerge, J.F.

    2010-11-24

    The SSRL Gun Test Facility (GTF) was built to develop a high brightness electron injector for the LCLS and has been operational since 1996. A total of five different metal cathodes (4 Cu and 1 Mg) have been installed on the GTF gun. The rf processing history with the different cathodes will be presented including peak field achieved at the cathode. The LCLS gun is intended to operate at 120 MV/m and fields up to 140 MV/m have been achieved in the GTF gun. After installing a new cathode the number of rf pulses required to reach 120 MV/m is approximately 5-10 million. Total emitted dark current and Fowler Nordheim plots are also shown over the life of the cathode. The GTF photo-injector gun is an S-band standing-wave structure, with two resonant cavities and an intervening thick washer (Figure 1). The flat, back wall of the first cavity is a copper plate that serves as photocathode when illuminated with ultraviolet light from a pulsed, high-power laser. RF power enters the gun through an iris on the outer wall of the second cavity, and is coupled to the first through the axial opening of the washer. The first cavity is often referred to as a half cell, because its full-cell length has been truncated by the cathode plate and the second cavity is called the full cell. The gun is designed to operate in a {pi} mode, with the peak field on axis in each cell approximately equal. The maximum in the half cell occurs at the cathode, and in the full cell near the center of the cavity. The field profile and tuning procedures are discussed in a separate tech note [1].

  16. Design of RF Systems for the RTD Mission VASIMR

    SciTech Connect

    Baity, F.W.; Barber, G.C.; Carter, M.D.; Chang-Diaz, F.R.; Goulding, R.H.; McCaskill, G.E.; Sparks, D.O.; Squire, J.P.

    1999-04-12

    The first flight test of the variable specific impulse magnetoplasma rocket (VASIMR) is tentatively scheduled for the Radiation and Technology Demonstration (RTD) in 2003. This mission to map the radiation environment out to several earth radii will employ both a Hall thruster and a VASIMR during its six months duration, beginning from low earth orbit. The mission will be powered by a solar array providing 12 kW of direct current electricity at 50 V. The VASIMR utilizes radiofrequency (RF) power both to generate a high-density plasma in a helicon source and to accelerate the plasma ions to high velocity by ion cyclotron resonance heating (ICRH). The VASIMR concept is being developed by the National Aeronautics and Space Administration (NASA) in collaboration with national laboratories and universities. Prototype plasma sources, RF amplifiers, and antennas are being developed in the experimental facilities of the Advanced Space Propulsion Laboratory (ASPL).

  17. Energetics of an rf SQUID Coupled to Two Thermal Reservoirs

    PubMed Central

    Gardas, B.; Łuczka, J.; Ptok, A.; Dajka, J.

    2015-01-01

    We study energetics of a Josephson tunnel junction connecting a superconducting loop pierced by an external magnetic flux (an rf SQUID) and coupled to two independent thermal reservoirs of different temperature. In the framework of the theory of quantum dissipative systems, we analyze energy currents in stationary states. The stationary energy flow can be periodically modulated by the external magnetic flux exemplifying the rf SQUID as a quantum heat interferometer. We also consider the transient regime and identify three distinct regimes: monotonic decay, damped oscillations and pulse-type behavior of energy currents. The first two regimes can be controlled by the external magnetic flux while the last regime is robust against its variation. PMID:26641890

  18. Energetics of an rf SQUID Coupled to Two Thermal Reservoirs

    SciTech Connect

    Gardas, B.; Łuczka, J.; Ptok, A.; Dajka, J.

    2015-12-07

    We study energetics of a Josephson tunnel junction connecting a superconducting loop pierced by an external magnetic flux (an rf SQUID) and coupled to two independent thermal reservoirs of different temperature. In the framework of the theory of quantum dissipative systems, we analyze energy currents in stationary states. The stationary energy flow can be periodically modulated by the external magnetic flux exemplifying the rf SQUID as a quantum heat interferometer. Additionally, we consider the transient regime and identify three distinct regimes: monotonic decay, damped oscillations and pulse-type behavior of energy currents. Furthermore, the first two regimes can be controlled by the external magnetic flux while the last regime is robust against its variation.

  19. Energetics of an rf SQUID Coupled to Two Thermal Reservoirs

    DOE PAGES

    Gardas, B.; Łuczka, J.; Ptok, A.; Dajka, J.

    2015-12-07

    We study energetics of a Josephson tunnel junction connecting a superconducting loop pierced by an external magnetic flux (an rf SQUID) and coupled to two independent thermal reservoirs of different temperature. In the framework of the theory of quantum dissipative systems, we analyze energy currents in stationary states. The stationary energy flow can be periodically modulated by the external magnetic flux exemplifying the rf SQUID as a quantum heat interferometer. Additionally, we consider the transient regime and identify three distinct regimes: monotonic decay, damped oscillations and pulse-type behavior of energy currents. Furthermore, the first two regimes can be controlled bymore » the external magnetic flux while the last regime is robust against its variation.« less

  20. Modeling and design of an X-band rf photoinjector

    NASA Astrophysics Data System (ADS)

    Marsh, R. A.; Albert, F.; Anderson, S. G.; Beer, G.; Chu, T. S.; Cross, R. R.; Deis, G. A.; Ebbers, C. A.; Gibson, D. J.; Houck, T. L.; Hartemann, F. V.; Barty, C. P. J.; Candel, A.; Jongewaard, E. N.; Li, Z.; Limborg-Deprey, C.; Vlieks, A. E.; Wang, F.; Wang, J. W.; Zhou, F.; Adolphsen, C.; Raubenheimer, T. O.

    2012-10-01

    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.

  1. Alternative RF coupling configurations for H{sup −} ion sources

    SciTech Connect

    Briefi, S.; Fantz, U.; Gutmann, P.

    2015-04-08

    RF heated sources for negative hydrogen ions both for fusion and accelerators require very high RF powers in order to achieve the required H{sup −} current what poses high demands on the RF generators and the RF circuit. Therefore it is highly desirable to improve the RF efficiency of the sources. This could be achieved by applying different RF coupling concepts than the currently used inductive coupling via a helical antenna, namely Helicon coupling or coupling via a planar ICP antenna enhanced with ferrites. In order to investigate the feasibility of these concepts, two small laboratory experiments have been set up. The PlanICE experiment, where the enhanced inductive coupling is going to be investigated, is currently under assembly. At the CHARLIE experiment systematic measurements concerning Helicon coupling in hydrogen and deuterium are carried out. The investigations show that a prominent feature of Helicon discharges occurs: the so-called low-field peak. This is a local improvement of the coupling efficiency at a magnetic field strength of a few mT which results in an increased electron density and dissociation degree. The full Helicon mode has not been achieved yet due to the limited available RF power and magnetic field strength but it might be sufficient for the application of the coupling concept to ion sources to operate the discharge in the low-field-peak region.

  2. Single electron beam rf feedback free electron laser

    DOEpatents

    Brau, C.A.; Stein, W.E.; Rockwood, S.D.

    1981-02-11

    A free electron laser system and electron beam system for a free electron laser which uses rf feedback to enhance efficiency are described. Rf energy is extracted from a single electron beam by decelerating cavities and energy is returned to accelerating cavities using rf returns, such as rf waveguides, rf feedthroughs, resonant feedthroughs, etc. This rf energy is added to rf klystron energy to reduce the required input energy and thereby enhance energy efficiency of the system.

  3. SITE TECHNOLOGY CAPSULE: IITRI RADIO FREQUENCY HEATING TECHNOLOGY

    EPA Science Inventory

    Radio frequency heating (RFH) technologies use electromagnetic energy in the radio frequency (RF) band to heat soil in situ, thereby potentially enhancing the performance of standard soil vapor extraction (SVE) technologies. Contaminants are removed from in situ soils and transfe...

  4. Overview of the RF Systems for LCLS

    SciTech Connect

    McIntosh, P.; Akre, R.; Boyce, R.; Emma, P.; Hill, A.; Rago, C.; /SLAC

    2005-06-15

    The Linac Coherent Light Source (LCLS) at SLAC, when it becomes operational in 2009, will provide its user community with an X-ray source many orders of magnitude brighter than anything available in the world at that time [1]. The electron beam acceleration will be provided by existing and new RF systems capable of maintaining the amplitude and phase stability of each bunch to extremely tight tolerances. RF feedback control of the various RF systems will be fundamental in ensuring the beam arrives at the LCLS undulator at precisely the required energy and peak current phase. This paper details the requirements for RF stability for the various LCLS RF systems and also highlights proposals for how these injector and Linac RF systems can meet these tight constraints.

  5. High voltage RF feedthrough bushing

    DOEpatents

    Grotz, Glenn F.

    1984-01-01

    Described is a multi-element, high voltage radio frequency bushing for trmitting RF energy to an antenna located in a vacuum container. The bushing includes a center conductor of complex geometrical shape, an outer coaxial shield conductor, and a thin-walled hollow truncated cone insulator disposed between central and outer conductors. The shape of the center conductor, which includes a reverse curvature portion formed of a radially inwardly directed shoulder and a convex portion, controls the uniformity of the axial surface gradient on the insulator cone. The outer shield has a first substantially cylindrical portion and a second radially inwardly extending truncated cone portion.

  6. Dust Growth by RF Sputtering

    SciTech Connect

    Churton, B.; Samarian, A. A.; Coueedel, L.

    2008-09-07

    The effect of the dust particle growth by RF sputtering on glow discharge has been investigated. It has been found that the growth of dust particles modifies the electrical characteristics of the discharge. In particularly, the absolute value of the self-bias voltage decreases during the particle growth due to the electron losses on the dust particles. To find the correlation between the dust growth and the self bias evolution, dust particles have been collected at different times. The dust particle growth rate is found to be linear.

  7. Robust multiplatform RF emitter localization

    NASA Astrophysics Data System (ADS)

    Al Issa, Huthaifa; Ordóñez, Raúl

    2012-06-01

    In recent years, position based services has increase. Thus, recent developments in communications and RF technology have enabled system concept formulations and designs for low-cost radar systems using state-of-the-art software radio modules. This research is done to investigate a novel multi-platform RF emitter localization technique denoted as Position-Adaptive RF Direction Finding (PADF). The formulation is based on the investigation of iterative path-loss (i.e., Path Loss Exponent, or PLE) metrics estimates that are measured across multiple platforms in order to autonomously adapt (i.e. self-adjust) of the location of each distributed/cooperative platform. Experiments conducted at the Air-Force Research laboratory (AFRL) indicate that this position-adaptive approach exhibits potential for accurate emitter localization in challenging embedded multipath environments such as in urban environments. The focus of this paper is on the robustness of the distributed approach to RF-based location tracking. In order to localize the transmitter, we use the Received Signal Strength Indicator (RSSI) data to approximate distance from the transmitter to the revolving receivers. We provide an algorithm for on-line estimation of the Path Loss Exponent (PLE) that is used in modeling the distance based on Received Signal Strength (RSS) measurements. The emitter position estimation is calculated based on surrounding sensors RSS values using Least-Square Estimation (LSE). The PADF has been tested on a number of different configurations in the laboratory via the design and implementation of four IRIS wireless sensor nodes as receivers and one hidden sensor as a transmitter during the localization phase. The robustness of detecting the transmitters position is initiated by getting the RSSI data through experiments and then data manipulation in MATLAB will determine the robustness of each node and ultimately that of each configuration. The parameters that are used in the functions are

  8. MEMS technologies for rf communications

    NASA Astrophysics Data System (ADS)

    Wu, Qun; Kim, B. K.

    2001-04-01

    Microelectromechanical system (MEMS) represents an exciting new technology derived from the same fabricating processes used to make integrated circuits. The trends of growing importance of the wireless communications market is toward the system with minimal size, cost and power consumption. For the purpose of MEMS R&D used for wireless communications, a history and present situation of MEMS device development are reviewed in this paper, and an overview of MEMS research topics on RF communication applications and the state of the art technologies are also presented here.

  9. OPERATION OF THE RHIC RF SYSTEMS.

    SciTech Connect

    BRENNAN,J.M.; BLASKIEWICZ,M.; DELONG,J.; FISCHER,W.; HAYES,T.; SMITH,K.S.; ZALTSMAN,A.

    2003-05-12

    Operational aspects of the RHIC rf system are described. To date three different beam combinations have been collided for physics production: gold-gold, deuteron-gold, and proton-proton(polarized). To facilitate this flexibility the rf systems of the two rings are independent and self-sufficient. Techniques to cope with problems such as, injection/capture, beam loading, bunch shortening, and rf noise have evolved and are explained.

  10. Adjuvant liposomal doxorubicin markedly affects radiofrequency (RF) ablation-induced effects on periablational microvasculature

    PubMed Central

    Moussa, Marwan; Goldberg, S. Nahum; Tasawwar, Beenish; Sawant, Rupa R.; Levchenko, Tatyana; Kumar, Gaurav; Torchilin, Vladimir P.; Ahmed, Muneeb

    2013-01-01

    Purpose To evaluate the effects of radiofrequency (RF) ablation without and with adjuvant IV liposomal doxorubicin (Doxil®) on microvessel morphology and patency and intratumoral drug delivery and retention. Materials and Methods A total of 133 tumors/animals were used. First, single subcutaneous tumors (R3230 in Fischer rats, and 786-0 in nude mice) were randomized to receive RF alone or no treatment, and sacrificed 0-72hr post-treatment. Next, combined RF/liposomal doxorubicin (1mg given 15min post-RF) was studied in R3230 tumors at 0-72hr post-treatment. Histopathologic assessment including immunohistochemical staining for ced caspase-3), heat shock protein 70 and CD34 were performed to assess morphologic vessel appearance, vessel diameter, and microvascular density. Subsequently, animals were randomized to receive RF alone, RF/liposomal doxorubicin, or control tumors, followed by intravenous fluorescent-labeled liposomes (a surrogate marker) given 0-24hr post-RF to permit qualitative assessment. Results RF ablation alone results in enlarged and dysmorphic vessels from 0-4hr, peaking at 12-24hr post-RF, occurring preferentially closer to the electrode. The addition of doxorubicin resulted in earlier vessel contraction (mean vessel area 47539±9544μm² vs. 1854±458μm² for RF alone at 15min, p<0.05). Combined RF/liposomal doxorubicin produced similar fluorescence 1hr post-treatment (40.88±33.53 AU/μm² vs. 22.1±13.19 AU/μm², p=0.14), but significantly less fluorescence at 4hr (24.3±3.65 AU/μm² vs. 2.8 ±3.14 AU/μm², p<0.002) compared to RF alone denoting earlier reduction in microvascular patency. Conclusion RF ablation induces morphologic changes to vessels within the ablation zone lasting up to 12-24hr post-treatment. The addition liposomal doxorubicin causes early vessel contraction and a reduction in periablational microvascular patency. Such changes will likely need to be considered when determining optimal drug administration and imaging

  11. Reconfigurable RF CMOS Circuit for Cognitive Radio

    NASA Astrophysics Data System (ADS)

    Masu, Kazuya; Okada, Kenichi

    Cognitive radio and/or SDR (Software Defined Radio) inherently requires multi-band and multi standard wireless circuit. The circuit is implemented based on Si CMOS technology. In this article, the recent progress of Si RF CMOS is described and the reconfigurable RF CMOS circuit which was proposed by the authors is introduced. At the present and in the future, several kind of Si CMOS technology can be used for RF CMOS circuit implementation. The realistic RF CMOS circuit implementation toward cognitive and/or SDR is discussed.

  12. Radiofrequency heating pathways for gold nanoparticles.

    PubMed

    Collins, C B; McCoy, R S; Ackerson, B J; Collins, G J; Ackerson, C J

    2014-08-01

    This feature article reviews the thermal dissipation of nanoscopic gold under radiofrequency (RF) irradiation. It also presents previously unpublished data addressing obscure aspects of this phenomenon. While applications in biology motivated initial investigation of RF heating of gold nanoparticles, recent controversy concerning whether thermal effects can be attributed to nanoscopic gold highlight the need to understand the involved mechanism or mechanisms of heating. Both the nature of the particle and the nature of the RF field influence heating. Aspects of nanoparticle chemistry which may affect thermal dissipation include the hydrodynamic diameter of the particle, the oxidation state and related magnetism of the core, and the chemical nature of the ligand shell. Aspects of RF which may affect thermal dissipation include power, frequency and antenna designs that emphasize relative strength of magnetic or electric fields. These nanoparticle and RF properties are analysed in the context of three heating mechanisms proposed to explain gold nanoparticle heating in an RF field. This article also makes a critical analysis of the existing literature in the context of the nanoparticle preparations, RF structure, and suggested mechanisms in previously reported experiments.

  13. Radiofrequency heating pathways for gold nanoparticles.

    PubMed

    Collins, C B; McCoy, R S; Ackerson, B J; Collins, G J; Ackerson, C J

    2014-08-01

    This feature article reviews the thermal dissipation of nanoscopic gold under radiofrequency (RF) irradiation. It also presents previously unpublished data addressing obscure aspects of this phenomenon. While applications in biology motivated initial investigation of RF heating of gold nanoparticles, recent controversy concerning whether thermal effects can be attributed to nanoscopic gold highlight the need to understand the involved mechanism or mechanisms of heating. Both the nature of the particle and the nature of the RF field influence heating. Aspects of nanoparticle chemistry which may affect thermal dissipation include the hydrodynamic diameter of the particle, the oxidation state and related magnetism of the core, and the chemical nature of the ligand shell. Aspects of RF which may affect thermal dissipation include power, frequency and antenna designs that emphasize relative strength of magnetic or electric fields. These nanoparticle and RF properties are analysed in the context of three heating mechanisms proposed to explain gold nanoparticle heating in an RF field. This article also makes a critical analysis of the existing literature in the context of the nanoparticle preparations, RF structure, and suggested mechanisms in previously reported experiments. PMID:24962620

  14. Airborne RF Measurement System and Analysis of Representative Flight RF Environment

    NASA Technical Reports Server (NTRS)

    Koppen, Sandra V.; Ely, Jay J.; Smith, Laura J.; Jones, Richard A.; Fleck, Vincent J.; Salud, Maria Theresa; Mielnik, John

    2007-01-01

    Environmental radio frequency (RF) data over a broad band of frequencies were needed to evaluate the airspace around several airports. An RF signal measurement system was designed using a spectrum analyzer connected to an aircraft VHF/UHF navigation antenna installed on a small aircraft. This paper presents an overview of the RF measurement system and provides analysis of a sample of RF signal measurement data over a frequency range of 30 MHz to 1000 MHz.

  15. RF/optical shared aperture for high availability wideband communication RF/FSO links

    SciTech Connect

    Ruggiero, Anthony J; Pao, Hsueh-yuan; Sargis, Paul

    2014-04-29

    An RF/Optical shared aperture is capable of transmitting and receiving optical signals and RF signals simultaneously. This technology enables compact wide bandwidth communications systems with 100% availability in clear air turbulence, rain and fog. The functions of an optical telescope and an RF reflector antenna are combined into a single compact package by installing an RF feed at either of the focal points of a modified Gregorian telescope.

  16. RF/optical shared aperture for high availability wideband communication RF/FSO links

    SciTech Connect

    Ruggiero, Anthony J; Pao, Hsueh-yuan; Sargis, Paul

    2015-03-24

    An RF/Optical shared aperture is capable of transmitting and receiving optical signals and RF signals simultaneously. This technology enables compact wide bandwidth communications systems with 100% availability in clear air turbulence, rain and fog. The functions of an optical telescope and an RF reflector antenna are combined into a single compact package by installing an RF feed at either of the focal points of a modified Gregorian telescope.

  17. Results of a Survey of Residential Home Heating Fuel and Stove Type and Use in the Shiprock Area of the Navajo Nation

    USGS Publications Warehouse

    Bunnell, Joseph E.; Garcia, Linda V.

    2008-01-01

    For many Navajo people, coal provides an affordable and convenient means of home heating. However, coal combustion results in the formation and mobilization of materials that are known risk factors for respiratory and other diseases. The level of respiratory morbidity among the Navajo people is higher than can be explained by usual epidemiological risk factors. The Shiprock area of the Navajo Nation is somewhat unique in that atmospheric thermal inversions trap air pollution low to the ground, especially in winter. There are two large mine mouth coal-fired power plants located in the vicinity, with a third plant in the planning stages. Both of the existing power plants are exempt from regulation under the U.S. Environmental Protection Agency 1990 Amendments to the Clean Air Act due to their age. The purpose of this survey was to assess the fuel and stove type and use, and document other household characteristics that might be related to the exposure of potentially toxic coal combustion products. A total of 137 surveys was conducted in English and Navajo to ascertain and document fuel usage and the type, size and conditions of heating stoves used in both traditional and modern homes. Results have been presented to the community at the Shiprock Chapter in the Navajo language. To increase public awareness, ways to properly use and store coal and to improve stove function and ventilation were also shared.

  18. Development of fundamental power coupler for high-current superconducting RF cavity

    SciTech Connect

    Jain P.; Belomestnykh, S.; Ben-Zvi, I.; Xu, W.

    2012-05-20

    Brookhaven National Laboratory took a project of developing a 704 MHz five-cell superconducting RF cavity for high-current linacs, including Energy Recovery Linac (ERL) for planned electron-hadron collider eRHIC. The cavity will be fed by a high-power RF amplifier using a coaxial Fundamental Power Coupler (FPC), which delivers 20 kW of CW RF power to the cavity. The design of FPC is one of the important aspects as one has to take into account the heat losses dissipated on the surface of the conductor by RF fields along with that of the static heat load. Using a simple simulation model we show the temperature profile and the heat load dissipated along the coupler length. To minimize the heat load on FPC near the cavity end, a thermal intercept is required at an appropriate location on FPC. A 10 K intercept was chosen and its location optimized with our simulation code. The requirement on the helium gas flow rate for the effective heat removal from the thermal intercept is also discussed.

  19. RF power recovery feedback circulator

    DOEpatents

    Sharamentov, Sergey I.

    2011-03-29

    A device and method for improving the efficiency of RF systems having a Reflective Load. In the preferred embodiment, Reflected Energy from a superconducting resonator of a particle accelerator is reintroduced to the resonator after the phase of the Reflected Energy is aligned with the phase of the Supply Energy from a RF Energy Source. In one embodiment, a Circulator is used to transfer Reflected Energy from the Reflective Load into a Phase Adjuster which aligns the phase of the Reflected Energy with that of the Supply Energy. The phase-aligned energy is then combined with the Supply Energy, and reintroduced into the Reflective Load. In systems having a constant phase shift, the Phase Adjuster may be designed to shift the phase of the Reflected Energy by a constant amount using a Phase Shifter. In systems having a variety (variable) phase shifts, a Phase Shifter controlled by a phase feedback loop comprising a Phase Detector and a Feedback Controller to account for the various phase shifts is preferable.

  20. Barrier RF stacking at Fermilab

    SciTech Connect

    Weiren Chou et al.

    2003-06-04

    A key issue to upgrade the luminosity of the Tevatron Run2 program and to meet the neutrino requirement of the NuMI experiment at Fermilab is to increase the proton intensity on the target. This paper introduces a new scheme to double the number of protons from the Main Injector (MI) to the pbar production target (Run2) and to the pion production target (NuMI). It is based on the fact that the MI momentum acceptance is about a factor of four larger than the momentum spread of the Booster beam. Two RF barriers--one fixed, another moving--are employed to confine the proton beam. The Booster beams are injected off-momentum into the MI and are continuously reflected and compressed by the two barriers. Calculations and simulations show that this scheme could work provided that the Booster beam momentum spread can be kept under control. Compared with slip stacking, a main advantage of this new method is small beam loading effect thanks to the low peak beam current. The RF barriers can be generated by an inductive device, which uses nanocrystal magnet alloy (Finemet) cores and fast high voltage MOSFET switches. This device has been designed and fabricated by a Fermilab-KEK-Caltech team. The first bench test was successful. Beam experiments are being planned.

  1. RF sources for future colliders

    NASA Astrophysics Data System (ADS)

    Phillips, Robert M.

    1997-02-01

    As we push particle colliders to 1-TeV center-of-mass collision energy and beyond, we require much more from our RF energy sources, both in terms of the RF performance and the number required for a given machine. In order to conserve real estate, the operating frequency of future colliders is apt to be higher than the S-band used for the SLAC SLC. It is this inevitable trend toward higher frequencies which presents the source designer with the greatest challenge. This paper is about that challenge. For reasons which will become clear, as we go to frequencies substantially above X-band, we will require sources other than klystrons, probably of the type referred to as "fast-wave devices," such as FEL or gyro-based amplifiers, or two-beam accelerators. Because these are discussed elsewhere in this conference, I will stick to the klystron as my model in describing the challenges to be overcome, as well as the criteria which must be met by alternative sources for new accelerators.

  2. Superconducting DC and RF Properties of Ingot Niobium

    SciTech Connect

    Pashupati Dhakal, Gianluigi Ciovati, Peter Kneisel, Ganapati Rao Myneni

    2011-07-01

    The thermal conductivity, DC magnetization and penetration depth of large-grain niobium hollow cylindrical rods fabricated from ingots, manufactured by CBMM subjected to chemical and heat treatment were measured. The results confirm the influence of chemical and heat-treatment processes on the superconducting properties, with no significant dependence on the impurity concentrations in the original ingots. Furthermore, RF properties, such as the surface resistance and quench field of the niobium rods were measured using a TE{sub 011} cavity. The hollow niobium rod is the center conductor of this cavity, converting it to a coaxial cavity. The quench field is limited by the critical heat flux through the rods' cooling channel.

  3. Handbook for Gas Filled RF Cavity Aficionados'

    SciTech Connect

    Tollestrup, A.V.; Chung, Moses; Yonehara, Katsuya; /Fermilab

    2009-05-01

    The use of hydrogen gas filled RF cavities in muon cooling channels has been proposed by Rolland Johnson. Impressive results have been obtained toward attaining high voltage gradients and rapid training in preliminary tests done at the FNAL MTA facility. However, so far it has not been possible to test them under conditions where they were subject to the transversal of a high intensity particle beam. This note is an attempt to bring together a description of some of the pertinent physical processes that take place in the dilute plasma that is generated in the hydrogen gas by the beam. Two effects dominate. The first is that the free electrons generated can load down the cavity and transfer its energy to heating the gas. The second is a question of what happens to the plasma in the longer term. There is an enormous literature on the subject of the subject of dilute hydrogen plasmas and we can tap into this information in order to understand and predict the behavior of the cavity.

  4. Plasma-Surface Interactions and RF Antennas

    NASA Astrophysics Data System (ADS)

    Jenkins, Thomas; Smithe, D. N.; Beckwith, K.; Davidson, B. D.; Kruger, S. E.; Pankin, A. Y.; Roark, C. M.

    2015-11-01

    Implementation of recently developed finite-difference time-domain (FDTD) modeling techniques on high-performance computing platforms allows RF power flow, and antenna near- and far-field behavior, to be studied in realistic experimental ion-cyclotron resonance heating scenarios at previously inaccessible levels of resolution. We present results and 3D animations of high-performance (10k-100k core) FDTD simulations of Alcator C-Mod's field-aligned ICRF antenna on the Titan supercomputer, considering (a) the physics of slow wave excitation in the immediate vicinity of the antenna hardware and in the scrape-off layer for various edge densities, and (b) sputtering and impurity production, as driven by self-consistent sheath potentials at antenna surfaces. Related research efforts in low-temperature plasma modeling, including the use of proper orthogonal decomposition methods for PIC/fluid modeling and the development of plasma chemistry tools (e.g. a robust and flexible reaction database, principal path reduction analysis capabilities, and improved visualization options), will also be summarized. Supported by U.S. DoE SBIR Phase I/II Award DE-SC0009501 and ALCC/OLCF.

  5. Improved nuclear magnetic resonance apparatus having semitoroidal rf coil for use in topical NMR and NMR imaging

    DOEpatents

    Fukushima, E.; Roeder, S.B.W.; Assink, R.A.; Gibson, A.A.V.

    1984-01-01

    An improved nuclear magnetic resonance (NMR) apparatus for use in topical magnetic resonance (TMR) spectroscopy and other remote sensing NMR applications includes a semitoroidal radio frequency (rf) coil. The semitoroidal rf coil produces an effective alternating magnetic field at a distance from the poles of the coil, so as to enable NMR measurements to be taken from selected regions inside an object, particularly including human and other living subjects. The semitoroidal rf coil is relatively insensitive to magnetic interference from metallic objects located behind the coil, thereby rendering the coil particularly suited for use in both conventional and superconducting NMR magnets. The semitoroidal NMR coil can be constructed so that it emits little or no excess rf electric field associated with the rf magnetic field, thus avoiding adverse effects due to dielectric heating of the sample or to any other interaction of the electric field with the sample.

  6. Error sources affecting thermocouple thermometry in RF electromagnetic fields.

    PubMed

    Chakraborty, D P; Brezovich, I A

    1982-03-01

    Thermocouple thermometry errors in radiofrequency (typically 13, 56 MHZ) electromagnetic fields such as are encountered in hyperthermia are described. RF currents capacitatively or inductively coupled into the thermocouple-detector circuit produce errors which are a combination of interference, i.e., 'pick-up' error, and genuine rf induced temperature changes at the junction of the thermocouple. The former can be eliminated by adequate filtering and shielding; the latter is due to (a) junction current heating in which the generally unequal resistances of the thermocouple wires cause a net current flow from the higher to the lower resistance wire across the junction, (b) heating in the surrounding resistive material (tissue in hyperthermia), and (c) eddy current heating of the thermocouple wires in the oscillating magnetic field. Low frequency theories are used to estimate these errors under given operating conditions and relevant experiments demonstrating these effects and precautions necessary to minimize the errors are described. It is shown that at 13.56 MHz and voltage levels below 100 V rms these errors do not exceed 0.1 degrees C if the precautions are observed and thermocouples with adequate insulation (e.g., Bailey IT-18) are used. Results of this study are being currently used in our clinical work with good success.

  7. Iterative Methods to Solve Linear RF Fields in Hot Plasma

    NASA Astrophysics Data System (ADS)

    Spencer, Joseph; Svidzinski, Vladimir; Evstatiev, Evstati; Galkin, Sergei; Kim, Jin-Soo

    2014-10-01

    Most magnetic plasma confinement devices use radio frequency (RF) waves for current drive and/or heating. Numerical modeling of RF fields is an important part of performance analysis of such devices and a predictive tool aiding design and development of future devices. Prior attempts at this modeling have mostly used direct solvers to solve the formulated linear equations. Full wave modeling of RF fields in hot plasma with 3D nonuniformities is mostly prohibited, with memory demands of a direct solver placing a significant limitation on spatial resolution. Iterative methods can significantly increase spatial resolution. We explore the feasibility of using iterative methods in 3D full wave modeling. The linear wave equation is formulated using two approaches: for cold plasmas the local cold plasma dielectric tensor is used (resolving resonances by particle collisions), while for hot plasmas the conductivity kernel (which includes a nonlocal dielectric response) is calculated by integrating along test particle orbits. The wave equation is discretized using a finite difference approach. The initial guess is important in iterative methods, and we examine different initial guesses including the solution to the cold plasma wave equation. Work is supported by the U.S. DOE SBIR program.

  8. Absolute Temperature Monitoring Using RF Radiometry in the MRI Scanner.

    PubMed

    El-Sharkawy, Abdel-Monem M; Sotiriadis, Paul P; Bottomley, Paul A; Atalar, Ergin

    2006-11-01

    Temperature detection using microwave radiometry has proven value for noninvasively measuring the absolute temperature of tissues inside the body. However, current clinical radiometers operate in the gigahertz range, which limits their depth of penetration. We have designed and built a noninvasive radiometer which operates at radio frequencies (64 MHz) with ∼100-kHz bandwidth, using an external RF loop coil as a thermal detector. The core of the radiometer is an accurate impedance measurement and automatic matching circuit of 0.05 Ω accuracy to compensate for any load variations. The radiometer permits temperature measurements with accuracy of ±0.1°K, over a tested physiological range of 28° C-40° C in saline phantoms whose electric properties match those of tissue. Because 1.5 T magnetic resonance imaging (MRI) scanners also operate at 64 MHz, we demonstrate the feasibility of integrating our radiometer with an MRI scanner to monitor RF power deposition and temperature dosimetry, obtaining coarse, spatially resolved, absolute thermal maps in the physiological range. We conclude that RF radiometry offers promise as a direct, noninvasive method of monitoring tissue heating during MRI studies and thereby providing an independent means of verifying patient-safe operation. Other potential applications include titration of hyper- and hypo-therapies. PMID:18026562

  9. FinFET and UTBB for RF SOI communication systems

    NASA Astrophysics Data System (ADS)

    Raskin, Jean-Pierre

    2016-11-01

    Performance of RF integrated circuit (IC) is directly linked to the analog and high frequency characteristics of the transistors, the quality of the back-end of line process as well as the electromagnetic properties of the substrate. Thanks to the introduction of the trap-rich high-resistivity Silicon-on-Insulator (SOI) substrate on the market, the ICs requirements in term of linearity are fulfilled. Today partially depleted SOI MOSFET is the mainstream technology for RF SOI systems. Future generations of mobile communication systems will require transistors with better high frequency performance at lower power consumption. The advanced MOS transistors in competition are FinFET and Ultra Thin Body and Buried oxide (UTBB) SOI MOSFETs. Both devices have been intensively studied these last years. Most of the reported data concern their digital performance. In this paper, their analog/RF behavior is described and compared. Both show similar characteristics in terms of transconductance, Early voltage, voltage gain, self-heating issue but UTBB outperforms FinFET in terms of cutoff frequencies thanks to their relatively lower fringing parasitic capacitances.

  10. 47 CFR 101.1525 - RF safety.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false RF safety. 101.1525 Section 101.1525 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Service and Technical Rules for the 70/80/90 GHz Bands § 101.1525 RF safety. Licensees in the...

  11. 47 CFR 95.1125 - RF safety.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false RF safety. 95.1125 Section 95.1125 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO SERVICES Wireless Medical Telemetry Service (WMTS) General Provisions § 95.1125 RF safety. Portable...

  12. 47 CFR 95.1125 - RF safety.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false RF safety. 95.1125 Section 95.1125 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO SERVICES Wireless Medical Telemetry Service (WMTS) General Provisions § 95.1125 RF safety. Portable...

  13. 47 CFR 90.1335 - RF safety.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false RF safety. 90.1335 Section 90.1335 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Wireless Broadband Services in the 3650-3700 MHz Band § 90.1335 RF...

  14. 47 CFR 90.1335 - RF safety.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false RF safety. 90.1335 Section 90.1335 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Wireless Broadband Services in the 3650-3700 MHz Band § 90.1335 RF...

  15. 47 CFR 90.1335 - RF safety.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false RF safety. 90.1335 Section 90.1335 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Wireless Broadband Services in the 3650-3700 MHz Band § 90.1335 RF...

  16. 47 CFR 101.1525 - RF safety.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false RF safety. 101.1525 Section 101.1525 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Service and Technical Rules for the 70/80/90 GHz Bands § 101.1525 RF safety. Licensees in the...

  17. 47 CFR 101.1525 - RF safety.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false RF safety. 101.1525 Section 101.1525 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Service and Technical Rules for the 70/80/90 GHz Bands § 101.1525 RF safety. Licensees in the...

  18. 47 CFR 95.1125 - RF safety.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false RF safety. 95.1125 Section 95.1125 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO SERVICES Wireless Medical Telemetry Service (WMTS) General Provisions § 95.1125 RF safety. Portable...

  19. 47 CFR 101.1525 - RF safety.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false RF safety. 101.1525 Section 101.1525 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Service and Technical Rules for the 70/80/90 GHz Bands § 101.1525 RF safety. Licensees in the...

  20. 47 CFR 95.1125 - RF safety.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false RF safety. 95.1125 Section 95.1125 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO SERVICES Wireless Medical Telemetry Service (WMTS) General Provisions § 95.1125 RF safety. Portable...

  1. 47 CFR 101.1525 - RF safety.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false RF safety. 101.1525 Section 101.1525 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Service and Technical Rules for the 70/80/90 GHz Bands § 101.1525 RF safety. Licensees in the...

  2. 47 CFR 90.1335 - RF safety.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false RF safety. 90.1335 Section 90.1335 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Wireless Broadband Services in the 3650-3700 MHz Band § 90.1335 RF...

  3. RF-controlled implantable solid state switch

    NASA Technical Reports Server (NTRS)

    Fryer, T. B.

    1971-01-01

    Miniature, totally implantable, solid state RF-controlled switching circuit for biotelemetry systems consumes zero power in off condition and turns on or off by pulse of RF energy. Switch, the size of small coin, is reducible by integrated circuit techniques.

  4. 47 CFR 27.52 - RF safety.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false RF safety. 27.52 Section 27.52 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Technical Standards § 27.52 RF safety. Licensees and manufacturers are subject to...

  5. 47 CFR 95.1125 - RF safety.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false RF safety. 95.1125 Section 95.1125 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO SERVICES Wireless Medical Telemetry Service (WMTS) General Provisions § 95.1125 RF safety. Portable...

  6. 47 CFR 27.52 - RF safety.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false RF safety. 27.52 Section 27.52 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Technical Standards § 27.52 RF safety. Licensees and manufacturers are subject to...

  7. 47 CFR 27.52 - RF safety.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false RF safety. 27.52 Section 27.52 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Technical Standards § 27.52 RF safety. Licensees and manufacturers are subject to...

  8. 47 CFR 27.52 - RF safety.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false RF safety. 27.52 Section 27.52 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Technical Standards § 27.52 RF safety. Licensees and manufacturers are subject to...

  9. 47 CFR 90.1335 - RF safety.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false RF safety. 90.1335 Section 90.1335 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Wireless Broadband Services in the 3650-3700 MHz Band § 90.1335 RF...

  10. 47 CFR 27.52 - RF safety.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false RF safety. 27.52 Section 27.52 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Technical Standards § 27.52 RF safety. Licensees and manufacturers are subject to...

  11. RF switch positioner for communications satellite network

    NASA Technical Reports Server (NTRS)

    Storaasli, A. G.; Griesser, H. P.; Grant, R. W.

    1986-01-01

    The RF switch positioner is a simple, lightweight, redundant positioning mechanism used to reconfigure the antenna beam on the INTELSAT VI satellite. It simultaneously rotates approximately 100 squareax waveguide switches through a full 360 deg. The RF switch positioner has been space qualified and has performed to expectations in conjunction with the feed networks in range testing.

  12. RF SYSTEM FOR THE SNS ACCUMULATOR RING.

    SciTech Connect

    BLASKIEWICZ, M.; BRENNAN, J.M.; BRODOWSKI, J.; DELONG, J.; METH, M.; SMITH, K.; ZALTSMAN, A.

    2001-06-18

    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.

  13. Airborne RF Measurement System (ARMS) and Analysis of Representative Flight RF Environment

    NASA Technical Reports Server (NTRS)

    Koppen, Sandra V.; Ely, Jay J.; Smith, Laura J.; Jones, Richard A.; Fleck, Vincent J.; Salud, Maria Theresa; Mielnik, John J.

    2007-01-01

    Environmental radio frequency (RF) data over a broad band of frequencies (30 MHz to 1000 MHz) were obtained to evaluate the electromagnetic environment in airspace around several airports. An RF signal measurement system was designed utilizing a spectrum analyzer connected to the NASA Lancair Columbia 300 aircraft's VHF/UHF navigation antenna. This paper presents an overview of the RF measurement system and provides analysis of sample RF signal measurement data. This aircraft installation package and measurement system can be quickly returned to service if needed by future projects requiring measurement of an RF signal environment or exploration of suspected interference situations.

  14. Magnetoplasmonic RF mixing and nonlinear frequency generation

    NASA Astrophysics Data System (ADS)

    Firby, C. J.; Elezzabi, A. Y.

    2016-07-01

    We present the design of a magnetoplasmonic Mach-Zehnder interferometer (MZI) modulator facilitating radio-frequency (RF) mixing and nonlinear frequency generation. This is achieved by forming the MZI arms from long-range dielectric-loaded plasmonic waveguides containing bismuth-substituted yttrium iron garnet (Bi:YIG). The magnetization of the Bi:YIG can be driven in the nonlinear regime by RF magnetic fields produced around adjacent transmission lines. Correspondingly, the nonlinear temporal dynamics of the transverse magnetization component are mapped onto the nonreciprocal phase shift in the MZI arms, and onto the output optical intensity signal. We show that this tunable mechanism can generate harmonics, frequency splitting, and frequency down-conversion with a single RF excitation, as well as RF mixing when driven by two RF signals. This magnetoplasmonic component can reduce the number of electrical sources required to generate distinct optical modulation frequencies and is anticipated to satisfy important applications in integrated optics.

  15. R&D ERL: Low level RF

    SciTech Connect

    Smith, K.

    2010-01-15

    A superconducting RF (SRF) Energy Recovery Linac (ERL) is currently under development at the Collider-Accelerator Department (C-AD) at Brookhaven National Laboratory (BNL). The major components from an RF perspective are (a) a 5-cell SRF ERL cavity, (b) an SRF photocathode electron gun, and (c) a drive laser for the photocathode gun. Each of these RF subsystems has its own set of RF performance requirements, as well as common requirements for ensuring correct synchronism between them. A low level RF (LLRF) control system is currently under development, which seeks to leverage both technology and experience gained from the recently commissioned RHIC LLRF system upgrade. This note will review the LLRF system requirements and describe the system to be installed at the ERL.

  16. RF FEL for power beaming

    NASA Astrophysics Data System (ADS)

    Burke, Robert

    The laser device components associated with operating a radio frequency-free electron laser (RF-FEL) for beaming power from Earth were designed and tested. Analysis of the power beaming system requirements reveals that the FEL, identified by NASA as the laser of choice, is the major subsystem requiring demonstration before proceeding further in proving the efficacy of laser power beaming. Rocketdyne has identified a series of low cost, low risk demonstrations which proceed sequentially, as follows: (1) a 1 kW proof-of-principle demonstration; (2) a 150 kW demonstration of beaming power to a satellite; and (3) a MW class demonstration of Earth to lunar surface power transmission. This sequence of events can be completed in 5.5 years at a cost of $188M, with key milestones each year.

  17. RF Cavity Characterization with VORPAL

    SciTech Connect

    C. Nieter, C. Roark, P. Stoltz, C.D. Zhou, F. Marhauser

    2011-03-01

    When designing a radio frequency (RF) accelerating cavity structure various figures of merit are considered before coming to a final cavity design. These figures of merit include specific field and geometry based quantities such as the ratio of the shunt impedance to the quality factor (R/Q) or the normalized peak fields in the cavity. Other important measures of cavity performance include the peak surface fields as well as possible multipacting resonances in the cavity. High fidelity simulations of these structures can provide a good estimate of these important quantities before any cavity prototypes are built. We will present VORPAL simulations of a simple pillbox structure where these quantities can be calculated analytically and compare them to the results from the VORPAL simulations. We will then use VORPAL to calculate these figures of merit and potential multipacting resonances for two cavity designs under development at Jefferson National Lab for Project X.

  18. Design of rf conditioner cavities

    SciTech Connect

    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{sub 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.

  19. Properties of radio-frequency heated argon confined uranium plasmas

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Pure uranium hexafluoride (UF6) was injected into an argon confined, steady state, rf-heated plasma within a fused silica peripheral wall test chamber. Exploratory tests conducted using an 80 kW rf facility and different test chamber flow configurations permitted selection of the configuration demonstrating the best confinement characteristics and minimum uranium compound wall coating. The overall test results demonstrated applicable flow schemes and associated diagnostic techniques were developed for the fluid mechanical confinement and characterization of uranium within an rf plasma discharge when pure UF6 is injected for long test times into an argon-confined, high-temperature, high-pressure, rf-heated plasma.

  20. Superconducting cavities and modulated RF

    SciTech Connect

    Farkas, Z.D.

    1981-02-01

    If a cavity has an infinite Q/sub o/, 81.5% of the energy contained in a pulse incident upon the cavity is transferred into the cavity by the end of the pulse if the cavity Q/sub e/ is chosen so that the cavity time constant is 0.796 pulse width (T/sub a/). As Q/sug o/ decreases, the energy in the cavity at the end of the pulse decreases very slowly as long as T/sub a/ is much less than the unloaded cavity time constant, T/sub co/. SC cavities with very high Q/sub o/ enable one to obtain very high gradients with a low power cw source. At high gradients, however, one often does not attain the high Q/sub o/ predicted by theory. Therefore, if one is inteerested in attaining maximum energy in the cavity, as is the case for RF processing and diagnostics, for a given available source energy there is no point in keeping the power on for longer than 0.1 T/sub co/ because the energy expended after 0.1 T/sub co/ is wasted. Therefore, to attain high fields at moderate Q/sub o/, pulsed operation is indicated. This note derives the fields and energy stored and dissipated in the cavity when Q/sub e/ is optimized for a given T/sub a/. It shows how to use this data to measure Q/sub o/ of an SC cavity as a function of field level, how to process the cavity with high RF fields, how to operate SC cavities in the pulsed mode to obtain higher efficiencies and gradients. Experimental results are also reported.

  1. Development of a Movable Plunger Tuner for the High Power RF Cavity for the PEP II B Factory

    SciTech Connect

    Schwarz, H.D.; Fant, K.; Neubauer, Mark Stephen; Rimmer, R.A.; /LBL, Berkeley

    2011-08-26

    A 10 cm diameter by 5 cm travel plunger tuner was developed for the PEP-II RF copper cavity system. The single cell cavity including the tuner is designed to operate up to 150 kW of dissipated RF power. Spring finger contacts to protect the bellows from RF power are specially placed 8.5 cm away from the inside wall of the cavity to avoid fundamental and higher order mode resonances. The spring fingers are made of dispersion-strengthened copper to accommodate relatively high heating. The design, alignment, testing and performance of the tuner is described.

  2. RF System High Power Amplifier Software Conversion at Jefferson Lab

    SciTech Connect

    G. Lahti; H. Dong; T. Seegerger

    2006-10-31

    Jefferson Lab is in the process of converting the RF system from analog RF modules and non-smart high power amplifiers (HPAs) to digital RF modules and smart HPAs. The present analog RF module controls both the RF signal and the non-smart HPA hardware. The new digital RF module will only control the RF signal, so the new HPA must include embedded software. This paper will describe the conversion from a software perspective, including the initial testing, the intermediate mixed system of old and new units, and finally the totally new RF system.

  3. ASRDI oxygen technology survey. Volume 3: Heat transfer and fluid dynamics. Abstracts of selected technical reports and publications

    NASA Technical Reports Server (NTRS)

    Schmidt, A. F. (Editor)

    1972-01-01

    Selected information is presented from an assemblage of reports and publications on heat transfer and fluid dynamics with direct applicability to oxygen systems. For each document cited, an abstract has been prepared together with key words and a listing of most important references found in the document. Additionally, an author index, a subject index, and a key word index have been provided to simplify the retrieval of specific information from this work. In each subject area - e.g., boiling heat transfer - the individual citations are listed alphabetically by first author, with review papers dually noted under the appropriate subject category and under review papers. Of the documents reviewed and evaluated for inclusion in this publication, coverage of existing information directly concerned with oxygen was given primary emphasis. However, work not specifically oxygen-designated but considered applicable to oxygen by the reviewer e.g., a two-phase friction factor correlation derived from nitrogen experiments is occasionally given where no actual oxygen data exist, as an aid to the reader. Approximately 130 abstracts are listed.

  4. Micro-fabricated DC comparison calorimeter for RF power measurement.

    PubMed

    Neji, Bilel; Xu, Jing; Titus, Albert H; Meltzer, Joel

    2014-10-27

    Diode detection and bolometric detection have been widely used to measure radio frequency (RF) power. However, flow calorimeters, in particular micro-fabricated flow calorimeters, have been mostly unexplored as power meters. This paper presents the design, micro-fabrication and characterization of a flow calorimeter. This novel device is capable of measuring power from 100 μW to 200 mW. It has a 50-Ohm load that is heated by the RF source, and the heat is transferred to fluid in a microchannel. The temperature change in the fluid is measured by a thermistor that is connected in one leg of a Wheatstone bridge. The output voltage change of the bridge corresponds to the RF power applied to the load. The microfabricated device measures 25.4 mm × 50.8 mm, excluding the power supplies, microcontroller and fluid pump. Experiments demonstrate that the micro-fabricated sensor has a sensitivity up to 22 × 10⁻³ V/W. The typical resolution of this micro-calorimeter is on the order of 50 μW, and the best resolution is around 10 μW. The effective efficiency is 99.9% from 0−1 GHz and more than 97.5% at frequencies up to 4 GHz. The measured reflection coefficient of the 50-Ohm load and coplanar wave guide is less than −25 dB from 0−2 GHz and less than −16 dB at 2−4 GHz.

  5. RF Power and HOM Coupler Tutorial

    SciTech Connect

    Rusnak, B

    2003-10-28

    Radio frequency (RF) couplers are used on superconducting cavities to deliver RF power for creating accelerating fields and to remove unwanted higher-order mode power for reducing emittance growth and cryogenic load. RF couplers in superconducting applications present a number of interdisciplinary design challenges that need to be addressed, since poor performance in these devices can profoundly impact accelerator operations and the overall success of a major facility. This paper will focus on critical design issues for fundamental and higher order mode (HOM) power couplers, highlight a sampling of reliability-related problems observed in couplers, and discuss some design strategies for improving performance.

  6. Multi-level RF identification system

    DOEpatents

    Steele, Kerry D.; Anderson, Gordon A.; Gilbert, Ronald W.

    2004-07-20

    A radio frequency identification system having a radio frequency transceiver for generating a continuous wave RF interrogation signal that impinges upon an RF identification tag. An oscillation circuit in the RF identification tag modulates the interrogation signal with a subcarrier of a predetermined frequency and modulates the frequency-modulated signal back to the transmitting interrogator. The interrogator recovers and analyzes the subcarrier signal and determines its frequency. The interrogator generates an output indicative of the frequency of the subcarrier frequency, thereby identifying the responding RFID tag as one of a "class" of RFID tags configured to respond with a subcarrier signal of a predetermined frequency.

  7. Nb-Pb Superconducting RF Gun

    SciTech Connect

    Sekutowicz, J.; Iversen, J.; Kreps, G.; Moller, W.D.; Singer, W.; Singer, X.; Ben-Zvi, I.; Burrill, A.; Smedley, J.; Rao, T.; Ferrario, M.; Kneisel, P.; Langner, J.; Strzyzewski, P.; Lefferts, R.; Lipski, A.; Szalowski, K.; Ko, K.; Xiao, L.; /SLAC

    2006-03-29

    We report on the status of an electron RF-gun made of two superconductors: niobium and lead. The presented design combines the advantages of the RF performance of bulk niobium superconducting cavities and the reasonably high quantum efficiency of lead, as compared to other superconducting metals. The concept, mentioned in a previous paper, follows the attractive approach of all niobium superconducting RF-gun as it has been proposed by the BNL group. Measured values of quantum efficiency for lead at various photon energies, analysis of recombination time of photon-broken Cooper pairs for lead and niobium, and preliminary cold test results are discussed in this paper.

  8. Nb-Pb superconducting RF gun

    SciTech Connect

    J. Sekutowicz; J. Iversen; G. Kreps; W.D. Moller; W. Singer; X. Singer; I. Ben-Zvi; A. Burrill; J. Smedley; T. Rao; M. Ferrario; P. Kneisel; J. Langner; P. Strzyzewski; R. Lefferts; A. Lipski; K. Szalowski; K. Ko; L. Xiao

    2006-04-14

    We report on the status of an electron RF-gun made of two superconductors: niobium and lead. The presented design combines the advantages of the RF performance of bulk niobium superconducting cavities and the reasonably high quantum efficiency of lead, as compared to other superconducting metals. The concept, mentioned in a previous paper, follows the attractive approach of all niobium superconducting RF-gun as it has been proposed by the BNL group. Measured values of quantum efficiency for lead at various photon energies, analysis of recombination time of photon-broken Cooper pairs for lead and niobium, and preliminary cold test results are discussed in this paper.

  9. Matching network for RF plasma source

    SciTech Connect

    Pickard, Daniel S.; Leung, Ka-Ngo

    2007-11-20

    A compact matching network couples an RF power supply to an RF antenna in a plasma generator. The simple and compact impedance matching network matches the plasma load to the impedance of a coaxial transmission line and the output impedance of an RF amplifier at radio frequencies. The matching network is formed of a resonantly tuned circuit formed of a variable capacitor and an inductor in a series resonance configuration, and a ferrite core transformer coupled to the resonantly tuned circuit. This matching network is compact enough to fit in existing compact focused ion beam systems.

  10. PEP surveying procedures and equipment

    SciTech Connect

    Linker, F.

    1982-06-01

    The PEP Survey and Alignment System, which employs both laser-based and optical survey methods, is described. The laser is operated in conjunction with the Tektronix 4051 computer and surveying instruments such as ARM and SAM, system which is designed to automate data input, reduction, and production of alignment instructions. The laser system is used when surveying ring quadrupoles, main bend magnets, sextupoles, and is optional when surveying RF cavities and insertion quadrupoles. Optical methods usually require that data be manually entered into the computer for alignment, but in some cases, an element can be aligned using nominal values of fiducial locations without use of the computer. Optical surveying is used in the alignment of NIT and SIT, low field bend magnets, wigglers, RF cavities, and insertion quadrupoles.

  11. RF Negative Ion Source Development at IPP Garching

    SciTech Connect

    Kraus, W.; McNeely, P.; Berger, M.; Christ-Koch, S.; Falter, H. D.; Fantz, U.; Franzen, P.; Froeschle, M.; Heinemann, B.; Leyer, S.; Riedl, R.; Speth, E.; Wuenderlich, D.

    2007-08-10

    IPP Garching is heavily involved in the development of an ion source for Neutral Beam Heating of the ITER Tokamak. RF driven ion sources have been successfully developed and are in operation on the ASDEX-Upgrade Tokamak for positive ion based NBH by the NB Heating group at IPP Garching. Building on this experience a RF driven H- ion source has been under development at IPP Garching as an alternative to the ITER reference design ion source. The number of test beds devoted to source development for ITER has increased from one (BATMAN) by the addition of two test beds (MANITU, RADI). This paper contains descriptions of the three test beds. Results on diagnostic development using laser photodetachment and cavity ringdown spectroscopy are given for BATMAN. The latest results for long pulse development on MANITU are presented including the to date longest pulse (600 s). As well, details of source modifications necessitated for pulses in excess of 100 s are given. The newest test bed RADI is still being commissioned and only technical details of the test bed are included in this paper. The final topic of the paper is an investigation into the effects of biasing the plasma grid.

  12. RF Negative Ion Source Development at IPP Garching

    NASA Astrophysics Data System (ADS)

    Kraus, W.; McNeely, P.; Berger, M.; Christ-Koch, S.; Falter, H. D.; Fantz, U.; Franzen, P.; Fröschle, M.; Heinemann, B.; Leyer, S.; Riedl, R.; Speth, E.; Wünderlich, D.

    2007-08-01

    IPP Garching is heavily involved in the development of an ion source for Neutral Beam Heating of the ITER Tokamak. RF driven ion sources have been successfully developed and are in operation on the ASDEX-Upgrade Tokamak for positive ion based NBH by the NB Heating group at IPP Garching. Building on this experience a RF driven H- ion source has been under development at IPP Garching as an alternative to the ITER reference design ion source. The number of test beds devoted to source development for ITER has increased from one (BATMAN) by the addition of two test beds (MANITU, RADI). This paper contains descriptions of the three test beds. Results on diagnostic development using laser photodetachment and cavity ringdown spectroscopy are given for BATMAN. The latest results for long pulse development on MANITU are presented including the to date longest pulse (600 s). As well, details of source modifications necessitated for pulses in excess of 100 s are given. The newest test bed RADI is still being commissioned and only technical details of the test bed are included in this paper. The final topic of the paper is an investigation into the effects of biasing the plasma grid.

  13. System studies of rf current drive for MST

    NASA Astrophysics Data System (ADS)

    Anderson, J. K.; Burke, D. R.; Diem, S.; Forest, C. B.; Goetz, J. A.; Harvey, R. W.; Hendries, E. R.; Kaufman, M. C.; Seltzman, A. H.; Thomas, M. A.

    2011-12-01

    Two rf schemes are being studied on the MST reversed field pinch for their potential in current profile control experiments. MHD modeling has shown that a substantial externally-driven off axis parallel current can improve stability of the dominant core tearing modes. A radially localized axisymmetric population of fast electrons has been observed by SXR emission during LH injection ( 100kW at 800MHz), and is consistent with CQL3D modeling which predicts a small driven current. Computational work suggests that doubling the input power will statistically improve the LH-induced SXR signal to background ratio, and that about 2MW of injected power (an order of magnitude increase) will drive enough current for stabilization of tearing modes. Additionally, a 1 MW 5.5 GHz electron Bernstein wave (EBW) experiment is under construction, which utilizes a very simple and compact antenna compatible with the demands of the RFP. EBW allows access to electron cyclotron heating and current drive in the overdense plasma. Coupling of the external electromagnetic wave to the EBW has been demonstrated, and initial tests at ˜100kW power have produced a small, localized xray flux consistent with rf heating and high diffusivity of fast electrons. Computational work is currently underway to answer the very important questions of how much power is required, and what level of electron diffusivity is tolerable, to generate a consequential amount of EBW current.

  14. Modeling and Optimizing RF Multipole Ion Traps

    NASA Astrophysics Data System (ADS)

    Fanghaenel, Sven; Asvany, Oskar; Schlemmer, Stephan

    2016-06-01

    Radio frequency (rf) ion traps are very well suited for spectroscopy experiments thanks to the long time storage of the species of interest in a well defined volume. The electrical potential of the ion trap is determined by the geometry of its electrodes and the applied voltages. In order to understand the behavior of trapped ions in realistic multipole traps it is necessary to characterize these trapping potentials. Commercial programs like SIMION or COMSOL, employing the finite difference and/or finite element method, are often used to model the electrical fields of the trap in order to design traps for various purposes, e.g. introducing light from a laser into the trap volume. For a controlled trapping of ions, e.g. for low temperature trapping, the time dependent electrical fields need to be known to high accuracy especially at the minimum of the effective (mechanical) potential. The commercial programs are not optimized for these applications and suffer from a number of limitations. Therefore, in our approach the boundary element method (BEM) has been employed in home-built programs to generate numerical solutions of real trap geometries, e.g. from CAD drawings. In addition the resulting fields are described by appropriate multipole expansions. As a consequence, the quality of a trap can be characterized by a small set of multipole parameters which are used to optimize the trap design. In this presentation a few example calculations will be discussed. In particular the accuracy of the method and the benefits of describing the trapping potentials via multipole expansions will be illustrated. As one important application heating effects of cold ions arising from non-ideal multipole fields can now be understood as a consequence of imperfect field configurations.

  15. Capacitor analysis for rf antennas

    SciTech Connect

    Power, W.H.; Baity, F.W.; Hoffman, D.J.

    1987-01-01

    Commercially available vacuum capacitors have been used in radio frequency (rf) antenna designs. The dimensional envelope of the capacitors has adapted favorably to antenna concepts. However, capacitors that are commercially available have not demonstrated acceptable performance characteristics for maximum design currents of 800 A rms at 80 MHz and 1300 A rms at 30 MHz or for voltages of 50 kV peak. The reason for capacitor failure was investigated. The investigation consisted of establishing existing mechanical design features, defining desired operating criteria of key capacitor components, determining component design limitations, and developing a modified concept for testing. The design criteria included a variable capacitance range of 50 to 450 pF at the maximum current conditions. Effects of capacitor cooling by means of radiative transfer and forced convective transfer were considered. The resulting modified capacitor design concept uses as many components of the commercially available capacitors as possible. An apparatus for testing and evaluation was designed for the proposed capacitor concepts. Tests have demonstrated reliable operations at 750 A and 80 MHz cw on a similar design. 2 refs., 5 figs.

  16. Micropower RF material proximity sensor

    DOEpatents

    McEwan, Thomas E.

    1998-01-01

    A level detector or proximity detector for materials capable of sensing through plastic container walls or encapsulating materials is of the sensor. Thus, it can be used in corrosive environments, as well as in a wide variety of applications. An antenna has a characteristic impedance which depends on the materials in proximity to the antenna. An RF oscillator, which includes the antenna and is based on a single transistor in a Colpitt's configuration, produces an oscillating signal. A detector is coupled to the oscillator which signals changes in the oscillating signal caused by changes in the materials in proximity to the antenna. The oscillator is turned on and off at a pulse repetition frequency with a low duty cycle to conserve power. The antenna consists of a straight monopole about one-quarter wavelength long at the nominal frequency of the oscillator. The antenna may be horizontally disposed on a container and very accurately detects the fill level within the container as the material inside the container reaches the level of the antenna.

  17. Micropower RF material proximity sensor

    DOEpatents

    McEwan, T.E.

    1998-11-10

    A level detector or proximity detector for materials capable of sensing through plastic container walls or encapsulating materials is disclosed. Thus, it can be used in corrosive environments, as well as in a wide variety of applications. An antenna has a characteristic impedance which depends on the materials in proximity to the antenna. An RF oscillator, which includes the antenna and is based on a single transistor in a Colpitt`s configuration, produces an oscillating signal. A detector is coupled to the oscillator which signals changes in the oscillating signal caused by changes in the materials in proximity to the antenna. The oscillator is turned on and off at a pulse repetition frequency with a low duty cycle to conserve power. The antenna consists of a straight monopole about one-quarter wavelength long at the nominal frequency of the oscillator. The antenna may be horizontally disposed on a container and very accurately detects the fill level within the container as the material inside the container reaches the level of the antenna. 5 figs.

  18. Design of rf-cavities in the funnel of accelerators for transmutation technologies

    SciTech Connect

    Krawczyk, F.L.; Bultman, N.K.; Chan, K.D.C.; Martineau, R.L.; Nath, S.; Young, L.M.

    1994-09-01

    Funnels are a key component of accelerator structures proposed for transmutation technologies. In addition to conventional accelerator elements, specialized rf-cavities are needed for these structures. Simulations were done to obtain their electromagnetic field distribution and to minimize the rf-induced heat loads. Using these results a structural and thermal analysis of these cavities was performed to insure their reliability at high average power and to determine their cooling requirements. For one cavity the thermal expansion data in return was used to estimate the thermal detuning.

  19. Steady state plasma operation in RF dominated regimes on EAST

    SciTech Connect

    Zhang, X. J.; Zhao, Y. P.; Gong, X. Z.; Hu, C. D.; Liu, F. K.; Hu, L. Q.; Wan, B. N. Li, J. G.

    2015-12-10

    Significant progress has recently been made on EAST in the 2014 campaign, including the enhanced CW H&CD system over 20MW heating power (LHCD, ICRH and NBI), more than 70 diagnostics, ITER-like W-monoblock on upper divertor, two inner cryo-pumps and RMP coils, enabling EAST to investigate long pulse H mode operation with dominant electron heating and low torque to address the critical issues for ITER. H-mode plasmas were achieved by new H&CD system or 4.6GHz LHCD alone for the first time. Long pulse high performance H mode has been obtained by LHCD alone up to 28s at H{sub 98}∼1.2 or by combing of ICRH and LHCD, no or small ELM was found in RF plasmas, which is essential for steady state operation in the future Tokamak. Plasma operation in low collision regimes were implemented by new 4.6GHz LHCD with core Te∼4.5keV. The non-inductive scenarios with high performance at high bootstrap current fraction have been demonstrated in RF dominated regimes for long pulse operation. Near full non-inductive CD discharges have been achieved. In addition, effective heating and decoupling method under multi-transmitter for ICRF system were developed in this campaign, etc. EAST could be in operation with over 30MW CW heating and current drive power (LHCD ICRH NBI and ECRH), enhanced diagnostic capabilities and full actively-cooled metal wall from 2015. It will therefore allow to access new confinement regimes and to extend these regimes towards to steady state operation.

  20. Asymptotic analysis of rf-heated collisional plasma

    SciTech Connect

    Fisch, N.J.; Karney, C.F.F.

    1985-03-01

    It is shown that a distribution of electrons in resonance with traveling waves, but colliding with background distributions of electrons and ions, evolves to a steady state. Details of the steady state are given analytically in the asymptotic limit of high electron energy and are compared with numerical solutions. The asymptotic analytic solution may be useful for quickly relating emission data to likely excitations and is more reliable than conventional numerical solutions at high energy. A method of improving numerics at high energy is suggested.

  1. Modular open RF architecture: extending VICTORY to RF systems

    NASA Astrophysics Data System (ADS)

    Melber, Adam; Dirner, Jason; Johnson, Michael

    2015-05-01

    Radio frequency products spanning multiple functions have become increasingly critical to the warfighter. Military use of the electromagnetic spectrum now includes communications, electronic warfare (EW), intelligence, and mission command systems. Due to the urgent needs of counterinsurgency operations, various quick reaction capabilities (QRCs) have been fielded to enhance warfighter capability. Although these QRCs were highly successfully in their respective missions, they were designed independently resulting in significant challenges when integrated on a common platform. This paper discusses how the Modular Open RF Architecture (MORA) addresses these challenges by defining an open architecture for multifunction missions that decomposes monolithic radio systems into high-level components with welldefined functions and interfaces. The functional decomposition maximizes hardware sharing while minimizing added complexity and cost due to modularization. MORA achieves significant size, weight and power (SWaP) savings by allowing hardware such as power amplifiers and antennas to be shared across systems. By separating signal conditioning from the processing that implements the actual radio application, MORA exposes previously inaccessible architecture points, providing system integrators with the flexibility to insert third-party capabilities to address technical challenges and emerging requirements. MORA leverages the Vehicular Integration for Command, Control, Communication, Computers, Intelligence, Surveillance, and Reconnaissance (C4ISR)/EW Interoperability (VICTORY) framework. This paper concludes by discussing how MORA, VICTORY and other standards such as OpenVPX are being leveraged by the U.S. Army Research, Development, and Engineering Command (RDECOM) Communications Electronics Research, Development, and Engineering Center (CERDEC) to define a converged architecture enabling rapid technology insertion, interoperability and reduced SWaP.

  2. Interventional Device Visualization with Toroidal Transceiver and Optically-Coupled Current Sensor for RF Safety Monitoring

    PubMed Central

    Etezadi-Amoli, Maryam; Stang, Pascal; Kerr, Adam; Pauly, John; Scott, Greig

    2014-01-01

    Purpose The development of catheters and guidewires that are safe from radiofrequency (RF)-induced heating and clearly visible against background tissue is a major challenge in interventional MRI. An interventional imaging approach using a toroidal transmit-receive (transceive) coil is presented. This toroidal transceiver allows controlled, low levels of RF current to flow in the catheter/guidewire for visualization, and can be used with conductive interventional devices that have a localized low-impedance tip contact. Methods Toroidal transceivers were built, and phantom experiments were performed to quantify transmit power levels required for device visibility and to detect heating hazards. Imaging experiments in a pig cadaver tested the extendibility to higher field strength and non-phantom settings. A photonically-powered optically-coupled toroidal current sensor for monitoring induced RF currents was built, calibrated, and tested using an independent image-based current estimation method. Results Results indicate that high-SNR visualization is achievable using milliwatts of transmit power—power levels orders of magnitude lower than levels that induce measurable heating in phantom tests. Agreement between image-based current estimates and RF current sensor measurements validates sensor accuracy. Conclusion The toroidal transceiver, integrated with power and current sensing, could offer a promising platform for safe and effective interventional device visualization. PMID:24691876

  3. Gyrokinetic Calculations of Microinstabilities and Transport During RF H-Modes on Alcator C-Mod

    SciTech Connect

    M.H. Redi; C. Fiore; P. Bonoli; C. Bourdelle; R. Budny; W.D. Dorland; D. Ernst; G. Hammett; D. Mikkelsen; J. Rice; S. Wukitch

    2002-06-18

    Physics understanding for the experimental improvement of particle and energy confinement is being advanced through massively parallel calculations of microturbulence for simulated plasma conditions. The ultimate goal, an experimentally validated, global, non-local, fully nonlinear calculation of plasma microturbulence is still not within reach, but extraordinary progress has been achieved in understanding microturbulence, driving forces and the plasma response in recent years. In this paper we discuss gyrokinetic simulations of plasma turbulence being carried out to examine a reproducible, H-mode, RF heated experiment on the Alcator CMOD tokamak3, which exhibits an internal transport barrier (ITB). This off axis RF case represents the early phase of a very interesting dual frequency RF experiment, which shows density control with central RF heating later in the discharge. The ITB exhibits steep, spontaneous density peaking: a reduction in particle transport occurring without a central particle source. Since the central temperature is maintained while the central density is increasing, this also suggests a thermal transport barrier exists. TRANSP analysis shows that ceff drops inside the ITB. Sawtooth heat pulse analysis also shows a localized thermal transport barrier. For this ICRF EDA H-mode, the minority resonance is at r/a * 0.5 on the high field side. There is a normal shear profile, with q monotonic.

  4. Design of RF Power System for CPHS

    NASA Astrophysics Data System (ADS)

    Cheng, Cheng; Du, Taibin; Guan, Xialing

    The Compact Pulsed Hadron Source (CPHS) system has been proposed and designed by the Department of Engineering Physics of Tsinghua University in Beijing, China. It consists of an accelerator front-end-a highintensity ion source, a 3 MeV radiofrequency quadrupole linac (RFQ), and a 13 MeV drift-tube linac (DTL), a neutron target station, and some experimental stations. In design of our RF power supply, both RFQ and DTL share a single klystron which is capable of 2.5 MW peak RF power and a 3.33% duty factor. The 325 MHz klystron contains a modulating anode and has a 100 kW average output power. Portions of the RF power system, such as pulsed high voltage power supply, modulator, crowbar protection and RF power transmission are all presented in details in this paper.

  5. CEBAF'S New RF Separator Structure Test Results

    SciTech Connect

    Reza Kazimi; Jock Fugitt; A. Krycuk; Charles Sinclair; Larry Turlington

    1993-05-01

    Prototypes of the rf separator for CEBAF have been made and successfully beam tested. The structure is a new design which has a high transverse shunt impedance together with a small transverse dimension compared to more conventional rf deflecting structures. Five rf separators will be used at CEBAF to allow beam from any one of the five recirculation passes to be delivered to any of the three experimental halls. The authors have already described the basic design of the structure and theoretical calculations. They have also reported some results from rf measurements and beam tests. In this paper they present more beam test results, their final design parameters, and test results of coupling two 1/2 wavelength cavities together.

  6. Degreasing and cleaning superconducting RF Niobium cavities

    SciTech Connect

    Rauchmiller, Michael; Kellett, Ron; /Fermilab

    2011-09-01

    The purpose and scope of this report is to detail the steps necessary for degreasing and cleaning of superconducting RF Niobium cavities in the A0 clean room. It lists the required equipment and the cleaning procedure.

  7. Single frequency RF powered ECG telemetry system

    NASA Technical Reports Server (NTRS)

    Ko, W. H.; Hynecek, J.; Homa, J.

    1979-01-01

    It has been demonstrated that a radio frequency magnetic field can be used to power implanted electronic circuitry for short range telemetry to replace batteries. A substantial reduction in implanted volume can be achieved by using only one RF tank circuit for receiving the RF power and transmitting the telemetered information. A single channel telemetry system of this type, using time sharing techniques, was developed and employed to transmit the ECG signal from Rhesus monkeys in primate chairs. The signal from the implant is received during the period when the RF powering radiation is interrupted. The ECG signal is carried by 20-microsec pulse position modulated pulses, referred to the trailing edge of the RF powering pulse. Satisfactory results have been obtained with this single frequency system. The concept and the design presented may be useful for short-range long-term implant telemetry systems.

  8. Si-based RF MEMS components.

    SciTech Connect

    Stevens, James E.; Nordquist, Christopher Daniel; Baker, Michael Sean; Fleming, James Grant; Stewart, Harold D.; Dyck, Christopher William

    2005-01-01

    Radio frequency microelectromechanical systems (RF MEMS) are an enabling technology for next-generation communications and radar systems in both military and commercial sectors. RF MEMS-based reconfigurable circuits outperform solid-state circuits in terms of insertion loss, linearity, and static power consumption and are advantageous in applications where high signal power and nanosecond switching speeds are not required. We have demonstrated a number of RF MEMS switches on high-resistivity silicon (high-R Si) that were fabricated by leveraging the volume manufacturing processes available in the Microelectronics Development Laboratory (MDL), a Class-1, radiation-hardened CMOS manufacturing facility. We describe novel tungsten and aluminum-based processes, and present results of switches developed in each of these processes. Series and shunt ohmic switches and shunt capacitive switches were successfully demonstrated. The implications of fabricating on high-R Si and suggested future directions for developing low-loss RF MEMS-based circuits are also discussed.

  9. New developments in RF power sources

    SciTech Connect

    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.

  10. Prototype rf cavity for the HISTRAP accelerator

    SciTech Connect

    Mosko, S.W.; Dowling, D.T.; Olsen, D.K.

    1989-01-01

    HISTRAP, a proposed synchrotron-cooling-storage ring designed to both accelerate and decelerate very highly charged very heavy ions for atomic physics research, requires an rf accelerating system to provide /+-/2.5 kV of peak accelerating voltage per turn while tuning through a 13.5:1 frequency range in a fraction of a second. A prototype half-wave, single gap rf cavity with biased ferrite tuning was built and tested over a continuous tuning range of 200 kHz through 2.7 MHz. Initial test results establish the feasibility of using ferrite tuning at the required rf power levels. The resonant system is located entirely outside of the accelerator's 15cm ID beam line vacuum enclosure except for a single rf window which serves as an accelerating gap. Physical separation of the cavity and the beam line permits in situ vacuum baking of the beam line at 300/degree/C.

  11. Normal Conducting RF Cavity for MICE

    SciTech Connect

    Li, D.; DeMello, A.; Virostek, S.; Zisman, M.; Summers, D.

    2010-05-23

    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.

  12. Fast beam stacking using rf barriers

    SciTech Connect

    Chou, W.; Capista, D.; Griffin, J.; Ng, K.-Y.; Wildman, D.; /Fermilab

    2007-06-01

    Two barrier RF systems were fabricated, tested and installed in the Fermilab Main Injector. Each can provide 8 kV rectangular pulses (the RF barriers) at 90 kHz. When a stationary barrier is combined with a moving barrier, injected beams from the Booster can be continuously deflected, folded and stacked in the Main Injector, which leads to doubling of the beam intensity. This paper gives a report on the beam experiment using this novel technology.

  13. RF MEMS reconfigurable triangular patch antenna.

    SciTech Connect

    Nordquist, Christopher Daniel; Christodoulou, Christos George; Feldner, Lucas Matthew

    2005-01-01

    A Ka-band RF MEMS enabled frequency reconfigurable triangular microstrip patch antenna has been designed for monolithic integration with RF MEMS phase shifters to demonstrate a low-cost monolithic passive electronically scanned array (PESA). This paper introduces our first prototype reconfigurable triangular patch antenna currently in fabrication. The aperture coupled patch antenna is fabricated on a dual-layer quartz/alumina substrate using surface micromachining techniques.

  14. RF MEMS reconfigurable triangular patch antenna.

    SciTech Connect

    Christodoulou, Christos George; Nordquist, Christopher Daniel; Feldner, Lucas Matthew

    2005-07-01

    A Ka-band RF MEMS enabled frequency reconfigurable triangular microstrip patch antenna has been designed for monolithic integration with RF MEMS phase shifters to demonstrate a low-cost monolithic passive electronically scanned array (PESA). This paper introduces our first prototype reconfigurable triangular patch antenna currently in fabrication. The aperture coupled patch antenna is fabricated on a dual-layer quartz/alumina substrate using surface micromachining techniques.

  15. Spontaneous fission of 256Rf, new data

    NASA Astrophysics Data System (ADS)

    Svirikhin, A. I.; Yeremin, A. V.; Izosimov, I. N.; Isaev, A. V.; Kuznetsov, A. N.; Malyshev, O. N.; Popeko, A. G.; Popov, Yu. A.; Sokol, E. A.; Chelnokov, M. L.; Chepigin, V. I.; Andel, B.; Asfari, M. Z.; Gall, B.; Yoshihiro, N.; Kalaninova, Z.; Mullins, S.; Piot, J.; Stefanova, E.; Tonev, D.

    2016-07-01

    Spontaneous fission properties of the short-lived neutron-deficient 256Rf nucleus produced in the complete fusion reaction with a beam of multiply charged heavy 50Ti ions from the U-400 cyclotron (FLNR, JINR) are experimentally investigated. Its half-life and decay branching ratio are measured. The average number of neutrons per spontaneous fission of 256Rf (bar v = 4.47 ± 0.09) is determined for the first time.

  16. A no-load RF calorimeter

    NASA Technical Reports Server (NTRS)

    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.

  17. RF study and 3-D simulations of a side-coupling thermionic RF-gun

    NASA Astrophysics Data System (ADS)

    Rimjaem, S.; Kusoljariyakul, K.; Thongbai, C.

    2014-02-01

    A thermionic RF-gun for generating ultra-short electron bunches was optimized, developed and used as a source at a linac-based THz radiation research laboratory of the Plasma and Beam Physics Research Facility, Chiang Mai University, Thailand. The RF-gun is a π/2-mode standing wave structure, which consists of two S-band accelerating cells and a side-coupling cavity. The 2856 MHz RF wave is supplied from an S-band klystron to the gun through the waveguide input-port at the cylindrical wall of the second cell. A fraction of the RF power is coupled from the second cell to the first one via a side-coupling cavity. Both the waveguide input-port and the side-coupling cavity lead to an asymmetric geometry of the gun. RF properties and electromagnetic field distributions inside the RF-gun were studied and numerically simulated by using computer codes SUPERFISH 7.19 and CST Microwave Studio 2012©. RF characterizations and tunings of the RF-gun were performed to ensure the reliability of the gun operation. The results from 3D simulations and measurements are compared and discussed in this paper. The influence of asymmetric field distributions inside the RF-gun on the electron beam properties was investigated via 3D beam dynamics simulations. A change in the coupling-plane of the side-coupling cavity is suggested to improve the gun performance.

  18. Movable RF probe eliminates need for calibration in plasma accelerators

    NASA Technical Reports Server (NTRS)

    Miller, D. B.

    1967-01-01

    Movable RF antenna probe in plasma accelerators continuously maps the RF field both within and beyond the accelerator. It eliminates the need for installing probes in the accelerator walls. The moving RF probe can be used to map the RF electrical field under various accelerator conditions.

  19. Overview of High Power Vacuum Dry RF Load Designs

    SciTech Connect

    Krasnykh, Anatoly

    2015-08-27

    A specific feature of RF linacs based on the pulsed traveling wave (TW) mode of operation is that only a portion of the RF energy is used for the beam acceleration. The residual RF energy has to be terminated into an RF load. Higher accelerating gradients require higher RF sources and RF loads, which can stably terminate the residual RF power. RF feeders (from the RF source though the accelerating section to the load) are vacuumed to transmit multi-megawatt high power RF. This overview will outline vacuumed RF loads only. A common method to terminate multi-MW RF power is to use circulated water (or other liquid) as an absorbing medium. A solid dielectric interface (a high quality ceramic) is required to separate vacuum and liquid RF absorber mediums. Using such RF load approaches in TW linacs is troubling because there is a fragile ceramic window barrier and a failure could become catastrophic for linac vacuum and RF systems. Traditional loads comprising of a ceramic disk have limited peak and average power handling capability and are therefore not suitable for high gradient TW linacs. This overview will focus on ''vacuum dry'' or ''all-metal'' loads that do not employ any dielectric interface between vacuum and absorber. The first prototype is an original design of RF loads for the Stanford Two-Mile Accelerator.

  20. The CEBAF RF Separator System Upgrade

    SciTech Connect

    J. Hovater; Mark Augustine; Al Guerra; Richard Nelson; Robert Terrell; Mark Wissmann

    2004-08-01

    The CEBAF accelerator uses RF deflecting cavities operating at the third sub-harmonic (499 MHz) of the accelerating frequency (1497 MHz) to ''kick'' the electron beam to the experimental halls. The cavities operate in a TEM dipole mode incorporating mode enhancing rods to increase the cavity's transverse shunt impedance [1]. As the accelerators energy has increased from 4 GeV to 6 GeV the RF system, specifically the 1 kW solid-state amplifiers, have become problematic, operating in saturation because of the increased beam energy demands. Two years ago we began a study to look into replacement for the RF amplifiers and decided to use a commercial broadcast Inductive Output Tube (IOT) capable of 30 kW. The new RF system uses one IOT amplifier on multiple cavities as opposed to one amplifier per cavity as was originally used. In addition, the new RF system supports a proposed 12 GeV energy upgrade to CEBAF. We are currently halfway through the upgrade with three IOTs in operation and the remaining one nearly installed. This paper reports on the new RF system and the IOT performance.

  1. Confinement improvement with rf poloidal current drive in the reversed-field pinch

    SciTech Connect

    Hokin, S.; Sarff, J.; Sovinec, C.; Uchimoto, E.

    1994-03-08

    External control of the current profile in a reversed-field pinch (RFP), by means such as rf poloidal current drive, may have beneficial effects well beyond the direct reduction of Ohmic input power due to auxiliary heating. Reduction of magnetic turbulence associated with the dynamo, which drives poloidal current in a conventional RFP, may allow operation at lower density and higher electron temperature, for which rf current drive becomes efficient and the RFP operates in a more favorable regime on the n{tau} vs T diagram. Projected parameters for RFX at 2 MA axe studied as a concrete example. If rf current drive allows RFX to operate with {beta} = 10% (plasma energy/magnetic energy) at low density (3 {times} 10{sup 19} m{sup {minus}3}) with classical resistivity (i.e. without dynamo-enhanced power input), 40 ms energy confinement times and 3 keV temperatures will result, matching the performance of tokamaks of similar size.

  2. Improved manufacturing techniques for rf and laser hardening of missile domes, phase 1

    NASA Astrophysics Data System (ADS)

    Pawlewicz, W. T.; Mann, I. B.; Martin, P. M.; Hays, D. D.; Graybeal, A. G.

    1982-07-01

    The adaptation of an existing Pacific Northwest Laboratory (PNL) optical coating capability developed for high power fusion laser applications to the case of RF and laser hardening of plastic missile domes used by US Army (MICOM) is reported. RF hardening of Hellfire and Copperhead 1.06 micron missile domes by use of transparent conductive Indium Tin Oxide (ITO) coatings is demonstrated. The project involved adaptation of a coating material and process developed for flat glass components used in fusion lasers to the case of hemispherical or conical heat sensitive plastic domes used on laser guided missiles. Specific ITO coating property goals are an electrical sheet resistance of 10 ohms/square, a coated dome transmission of 80% or more at 1.06 micron wavelength (compared to 90% for a bare dome), and good adhesion. The sheet resistance goal of 10 ohms/square was expected to result in an RF attenuation of 30 dB at the frequencies of importance.

  3. Cryo-EM visualization of the ribosome in termination complex with apo-RF3 and RF1

    PubMed Central

    Pallesen, Jesper; Hashem, Yaser; Korkmaz, Gürkan; Koripella, Ravi Kiran; Huang, Chenhui; Ehrenberg, Måns; Sanyal, Suparna; Frank, Joachim

    2013-01-01

    Termination of messenger RNA translation in Bacteria and Archaea is initiated by release factors (RFs) 1 or 2 recognizing a stop codon in the ribosomal A site and releasing the peptide from the P-site transfer RNA. After release, RF-dissociation is facilitated by the G-protein RF3. Structures of ribosomal complexes with RF1 or RF2 alone or with RF3 alone—RF3 bound to a non-hydrolyzable GTP-analog—have been reported. Here, we present the cryo-EM structure of a post-termination ribosome containing both apo-RF3 and RF1. The conformation of RF3 is distinct from those of free RF3•GDP and ribosome-bound RF3•GDP(C/N)P. Furthermore, the conformation of RF1 differs from those observed in RF3-lacking ribosomal complexes. Our study provides structural keys to the mechanism of guanine nucleotide exchange on RF3 and to an L12-mediated ribosomal recruitment of RF3. In conjunction with previous observations, our data provide the foundation to structurally characterize the complete action cycle of the G-protein RF3. DOI: http://dx.doi.org/10.7554/eLife.00411.001 PMID:23755360

  4. Measuring RF-induced currents inside implants: Impact of device configuration on MRI safety of cardiac pacemaker leads.

    PubMed

    Nordbeck, Peter; Weiss, Ingo; Ehses, Philipp; Ritter, Oliver; Warmuth, Marcus; Fidler, Florian; Herold, Volker; Jakob, Peter M; Ladd, Mark E; Quick, Harald H; Bauer, Wolfgang R

    2009-03-01

    Radiofrequency (RF)-related heating of cardiac pacemaker leads is a serious concern in magnetic resonance imaging (MRI). Recent investigations suggest such heating to be strongly dependent on an implant's position within the surrounding medium, but this issue is currently poorly understood. In this study, phantom measurements of the RF-induced electric currents inside a pacemaker lead were performed to investigate the impact of the device position and lead configuration on the amount of MRI-related heating at the lead tip. Seven hundred twenty device position/lead path configurations were investigated. The results show that certain configurations are associated with a highly increased risk to develop MRI-induced heating, whereas various configurations do not show any significant heating. It was possible to precisely infer implant heating on the basis of current intensity values measured inside a pacemaker lead. Device position and lead configuration relative to the surrounding medium are crucial to the amount of RF-induced heating in MRI. This indicates that a considerable number of implanted devices may incidentally not develop severe heating in MRI because of their specific configuration in the body. Small variations in configuration can, however, strongly increase the risk for such heating effects, meaning that hazardous situations might appear during MRI.

  5. Thermophilic spore-forming bacteria isolated from spoiled canned food and their heat resistance. Results of a French ten-year survey.

    PubMed

    André, S; Zuber, F; Remize, F

    2013-07-15

    Thermal processing of Low Acid Canned Foods (LACF), which are safe and shelf-stable at ambient temperature for several years, results in heat inactivation of all vegetative microorganisms and the partial or total inactivation of spores. Good Manufacturing Hygienic Practices include stability tests for managing the pathogen risk related to surviving mesophilic bacterial spores. LACF are also often submitted to additional incubation conditions, typically 55 °C for 7 days, to monitor spoilage by thermophiles. In this study we identified the bacterial species responsible for non-stability after prolonged at 55 °C of incubation of LACF from 455 samples collected from 122 French canneries over 10 years. Bacteria were identified by microsequencing or a recent developed tool for group-specific PCR detection (SporeTraQ™). A single species was identified for 93% of examined samples. Three genera were responsible for more than 80% of all non-stability cases: mostly Moorella (36%) and Geobacillus (35%), and less frequently Thermoanaerobacterium (10%). The other most frequent bacterial genera identified were Bacillus, Thermoanaerobacter, Caldanaerobius, Anoxybacillus, Paenibacillus and Clostridium. Species frequency was dependent on food category, i.e. vegetables, ready-made meals containing meat, seafood or other recipes, products containing fatty duck, and related to the intensity of the thermal treatment applied in these food categories. The spore heat resistance parameters (D or δ and z values) from 36 strains isolated in this study were determined. Taken together, our results single out the species most suitable for use as indicators for thermal process settings. This extensively-documented survey of the species that cause non-stability at 55 °C in LACF will help canneries to improve the management of microbial contamination. PMID:23728430

  6. RF Performance of Membrane Aperture Shells

    NASA Technical Reports Server (NTRS)

    Flint, Eirc M.; Lindler, Jason E.; Thomas, David L.; Romanofsky, Robert

    2007-01-01

    This paper provides an overview of recent results establishing the suitability of Membrane Aperture Shell Technology (MAST) for Radio Frequency (RF) applications. These single surface shells are capable of maintaining their figure with no preload or pressurization and minimal boundary support, yet can be compactly roll stowed and passively self deploy. As such, they are a promising technology for enabling a future generation of RF apertures. In this paper, we review recent experimental and numerical results quantifying suitable RF performance. It is shown that candidate materials possess metallic coatings with sufficiently low surface roughness and that these materials can be efficiently fabricated into RF relevant doubly curved shapes. A numerical justification for using a reflectivity metric, as opposed to the more standard RF designer metric of skin depth, is presented and the resulting ability to use relatively thin coating thickness is experimentally validated with material sample tests. The validity of these independent film sample measurements are then confirmed through experimental results measuring RF performance for reasonable sized doubly curved apertures. Currently available best results are 22 dBi gain at 3 GHz (S-Band) for a 0.5m aperture tested in prime focus mode, 28dBi gain for the same antenna in the C-Band (4 to 6 GHz), and 36.8dBi for a smaller 0.25m antenna tested at 32 GHz in the Ka-Band. RF range test results for a segmented aperture (one possible scaling approach) are shown as well. Measured antenna system actual efficiencies (relative to the unachievable) ideal for these on axis tests are generally quite good, typically ranging from 50 to 90%.

  7. RF pulse compression for future linear colliders

    SciTech Connect

    Wilson, P.B.

    1995-05-01

    Future (nonsuperconducting) linear colliders will require very high values of peak rf power per meter of accelerating structure. The role of rf pulse compression in producing this power is examined within the context of overall rf system design for three future colliders at energies of 1.0--1.5 TeV, 5 TeV and 25 TeV. In order keep the average AC input power and the length of the accelerator within reasonable limits, a collider in the 1.0--1.5 TeV energy range will probably be built at an x-band rf frequency, and will require a peak power on the order of 150--200 MW per meter of accelerating structure. A 5 TeV collider at 34 GHz with a reasonable length (35 km) and AC input power (225 MW) would require about 550 MW per meter of structure. Two-beam accelerators can achieve peak powers of this order by applying dc pulse compression techniques (induction linac modules) to produce the drive beam. Klystron-driven colliders achieve high peak power by a combination of dc pulse compression (modulators) and rf pulse compression, with about the same overall rf system efficiency (30--40%) as a two-beam collider. A high gain (6.8) three-stage binary pulse compression system with high efficiency (80%) is described, which (compared to a SLED-11 system) can be used to reduce the klystron peak power by about a factor of two, or alternately, to cut the number of klystrons in half for a 1.0--1.5 TeV x-band collider. For a 5 TeV klystron-driven collider, a high gain, high efficiency rf pulse compression system is essential.

  8. RF pulse compression for future linear colliders

    NASA Astrophysics Data System (ADS)

    Wilson, Perry B.

    1995-07-01

    Future (nonsuperconducting) linear colliders will require very high values of peak rf power per meter of accelerating structure. The role of rf pulse compression in producing this power is examined within the context of overall rf system design for three future colliders at energies of 1.0-1.5 TeV, 5 TeV, and 25 TeV. In order to keep the average AC input power and the length of the accelerator within reasonable limits, a collider in the 1.0-1.5 TeV energy range will probably be built at an x-band rf frequency, and will require a peak power on the order of 150-200 MW per meter of accelerating structure. A 5 TeV collider at 34 GHz with a reasonable length (35 km) and AC input power (225 MW) would require about 550 MW per meter of structure. Two-beam accelerators can achieve peak powers of this order by applying dc pulse compression techniques (induction linac modules) to produce the drive beam. Klystron-driven colliders achieve high peak power by a combination of dc pulse compression (modulators) and rf pulse compression, with about the same overall rf system efficiency (30-40%) as a two-beam collider. A high gain (6.8) three-stage binary pulse compression system with high efficiency (80%) is described, which (compared to a SLED-II system) can be used to reduce the klystron peak power by about a factor of two, or alternatively, to cut the number of klystrons in half for a 1.0-1.5 TeV x-band collider. For a 5 TeV klystron-driven collider, a high gain, high efficiency rf pulse compression system is essential.

  9. A 32-Channel Combined RF and B0 Shim Array for 3T Brain Imaging

    PubMed Central

    Stockmann, Jason P.; Witzel, Thomas; Keil, Boris; Polimeni, Jonathan R.; Mareyam, Azma; LaPierre, Cristen; Setsompop, Kawin; Wald, Lawrence L.

    2016-01-01

    Purpose We add user-controllable direct currents (DC) to the individual elements of a 32-channel radio-frequency (RF) receive array to provide B0 shimming ability while preserving the array’s reception sensitivity and parallel imaging performance. Methods Shim performance using constrained DC current (±2.5A) is simulated for brain arrays ranging from 8 to 128 elements. A 32-channel 3-tesla brain array is realized using inductive chokes to bridge the tuning capacitors on each RF loop. The RF and B0 shimming performance is assessed in bench and imaging measurements. Results The addition of DC currents to the 32-channel RF array is achieved with minimal disruption of the RF performance and/or negative side effects such as conductor heating or mechanical torques. The shimming results agree well with simulations and show performance superior to third-order spherical harmonic (SH) shimming. Imaging tests show the ability to reduce the standard frontal lobe susceptibility-induced fields and improve echo planar imaging geometric distortion. The simulation of 64- and 128-channel brain arrays suggest that even further shimming improvement is possible (equivalent to up to 6th-order SH shim coils). Conclusion Including user-controlled shim currents on the loops of a conventional highly parallel brain array coil is feasible with modest current levels and produces improved B0 shimming performance over standard second-order SH shimming. PMID:25689977

  10. MHD simulation of RF current drive in MST

    SciTech Connect

    Hendries, E. R.; Anderson, J. K.; Forest, C. B.; Reusch, J. A.; Seltzman, A. H.; Sovinec, C. R.; Diem, S.; Harvey, R. W.

    2014-02-12

    Auxiliary heating and current drive using RF waves such as the electron Bernstein wave (EBW) promises to advance the performance of the reversed field pinch (RFP). In previous computational work [1], a hypothetical edge-localized current drive is shown to suppress the tearing activity which governs the macroscopic transport properties of the RFP. The ideal conditions for tearing stabilization include a reduced toroidal induction, and precise width and radial position of the Gaussian-shaped external current drive. In support of the EBW experiment on the Madison Symmetric Torus, an integrated modeling scheme now incorporates ray tracing and Fokker-Plank predictions of auxiliary current into single fluid MHD. Simulations at low Lundquist number (S ∼ 10{sup 4}) generally agree with the previous work; significantly more burdensome simulations at MST-like Lundquist number (S ∼ 3×10{sup 6}) show unexpected results. The effect on nonlinearly saturated current profile by a particular RF-driven external force decreases in magnitude and widens considerably as the Lundquist number increases toward experimental values. Simulations reproduce the periodic current profile relaxation events observed in experiment (sawteeth) in the absence of current profile control. Reduction of the tearing mode amplitudes is still observable; however, reduction is limited to periods between the large bursts of magnetic activity at each sawtooth. The sawtoothing pattern persists with up to 10 MW of externally applied RF power. Periods with prolonged low tearing amplitude are predicted with a combination of external current drive and a reduced toroidal loop voltage, consistent with previous conclusions. Finally, the resistivity profile is observed to have a strong effect on the optimal externally driven current profile for mode stabilization.

  11. MHD simulation of RF current drive in MST

    NASA Astrophysics Data System (ADS)

    Hendries, E. R.; Anderson, J. K.; Diem, S.; Forest, C. B.; Harvey, R. W.; Reusch, J. A.; Seltzman, A. H.; Sovinec, C. R.

    2014-02-01

    Auxiliary heating and current drive using RF waves such as the electron Bernstein wave (EBW) promises to advance the performance of the reversed field pinch (RFP). In previous computational work [1], a hypothetical edge-localized current drive is shown to suppress the tearing activity which governs the macroscopic transport properties of the RFP. The ideal conditions for tearing stabilization include a reduced toroidal induction, and precise width and radial position of the Gaussian-shaped external current drive. In support of the EBW experiment on the Madison Symmetric Torus, an integrated modeling scheme now incorporates ray tracing and Fokker-Plank predictions of auxiliary current into single fluid MHD. Simulations at low Lundquist number (S ˜ 104) generally agree with the previous work; significantly more burdensome simulations at MST-like Lundquist number (S ˜ 3×106) show unexpected results. The effect on nonlinearly saturated current profile by a particular RF-driven external force decreases in magnitude and widens considerably as the Lundquist number increases toward experimental values. Simulations reproduce the periodic current profile relaxation events observed in experiment (sawteeth) in the absence of current profile control. Reduction of the tearing mode amplitudes is still observable; however, reduction is limited to periods between the large bursts of magnetic activity at each sawtooth. The sawtoothing pattern persists with up to 10 MW of externally applied RF power. Periods with prolonged low tearing amplitude are predicted with a combination of external current drive and a reduced toroidal loop voltage, consistent with previous conclusions. Finally, the resistivity profile is observed to have a strong effect on the optimal externally driven current profile for mode stabilization.

  12. Multipole and field uniformity tailoring of a 750 MHz rf dipole

    SciTech Connect

    Delayen, Jean R.; Castillo, Alejandro

    2014-12-01

    In recent years great interest has been shown in developing rf structures for beam separation, correction of geometrical degradation on luminosity, and diagnostic applications in both lepton and hadron machines. The rf dipole being a very promising one among all of them. The rf dipole has been tested and proven to have attractive properties that include high shunt impedance, low and balance surface fields, absence of lower order modes and far-spaced higher order modes that simplify their damping scheme. As well as to be a compact and versatile design in a considerable range of frequencies, its fairly simple geometry dependency is suitable both for fabrication and surface treatment. The rf dipole geometry can also be optimized for lowering multipacting risk and multipole tailoring to meet machine specific field uniformity tolerances. In the present work a survey of field uniformities, and multipole contents for a set of 750 MHz rf dipole designs is presented as both a qualitative and quantitative analysis of the inherent flexibility of the structure and its limitations.

  13. RF characterization and testing of ridge waveguide transitions for RF power couplers

    NASA Astrophysics Data System (ADS)

    Kumar, Rajesh; Jose, Mentes; Singh, G. N.; Kumar, Girish; Bhagwat, P. V.

    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.

  14. [Development of a radiofrequency device for heating superficial and deep-seated tumors].

    PubMed

    Sugahara, T

    1988-12-01

    The author described the procedure of RF heating of tumors using a heating system Thermotron RF-8 (8 MHz), developed in Japan. The results of the treatment of 63 patients were reported. Limitations of the method and ways of their overcoming were shown.

  15. Automatic impedance matching network for ICRH-RF experiments on SST-1

    NASA Astrophysics Data System (ADS)

    Joshi, R.; Singh, M.; Jadav, H. M.; Purohit, D.; George, Siju; Rajnish, K.; Singh, Raj; Kulkarni, S. V.; ICRH-RF Group

    2010-02-01

    Ion Cyclotron Resonance Heating (ICRH) is a promising heating method for a fusion device due to its localized power deposition profile, a direct ion heating at high density, and established technology for high power RF generation and transmission low cost. For the same reason 1.5-Megawatt ICRH system is developed indigenously for steady state super-conducting tokamak (SST-1). Since plasma-loading impedance is generally small as compared to the characteristic impedance of the transmission system, a significant amount of power will be reflected from the antenna back towards the generator giving very high reflections to SWR which can damage the high power RF tube. Hence matching network is used to match the total transmission line system to the antenna impedance so that the RF generator sees a matched load and can operate at high efficiency. In the ICRH system, coarse matching network and the on-line automatic matching network designed for the impedance matching of the system to transfer maximum power to the tokamak plasma during 1000 seconds operation. The plasma impedance varies in time on milliseconds scale and hence on-line impedance matching has to match the impedance on a faster scale to avoid the reflections as well as to transfer maximum power to the plasma for heating. There are two transmission lines connected with Hybrid coupler sourced by RF Generator (RF Power) 45.6 MHz frequency. Automatic matching network is connected with each transmission line, which offers on-line fine matching along with coarse matching system connected with transmission line. The matching system includes stubs, phase shifters and the automatic matching system consists of motorized vacuum variable capacitors connected to 9" transmission line. The method includes the detection of reflected power in transmission line with the help of probes, give a right signal to VME based data acquisition and control system to do calculations and generate the signal to vary the capacitance of

  16. RF BREAKDOWN STUDIES USING PRESSURIZED CAVITIES

    SciTech Connect

    Johnson, Rolland

    2014-09-21

    Many present and future particle accelerators are limited by the maximum electric gradient and peak surface fields that can be realized in RF cavities. Despite considerable effort, a comprehensive theory of RF breakdown has not been achieved and mitigation techniques to improve practical maximum accelerating gradients have had only limited success. Part of the problem is that RF breakdown in an evacuated cavity involves a complex mixture of effects, which include the geometry, metallurgy, and surface preparation of the accelerating structures and the make-up and pressure of the residual gas in which plasmas form. Studies showed that high gradients can be achieved quickly in 805 MHz RF cavities pressurized with dense hydrogen gas, as needed for muon cooling channels, without the need for long conditioning times, even in the presence of strong external magnetic fields. This positive result was expected because the dense gas can practically eliminate dark currents and multipacting. In this project we used this high pressure technique to suppress effects of residual vacuum and geometry that are found in evacuated cavities in order to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of magnetic field, frequency, and surface preparation. One of the interesting and useful outcomes of this project was the unanticipated collaborations with LANL and Fermilab that led to new insights as to the operation of evacuated normal-conducting RF cavities in high external magnetic fields. Other accomplishments included: (1) RF breakdown experiments to test the effects of SF6 dopant in H2 and He gases with Sn, Al, and Cu electrodes were carried out in an 805 MHz cavity and compared to calculations and computer simulations. The heavy corrosion caused by the SF6 components led to the suggestion that a small admixture of oxygen, instead of SF6, to the hydrogen would allow the same advantages without the corrosion in a practical muon beam line. (2) A

  17. High-resolution simulations of the thermophysiological effects of human exposure to 100 MHz RF energy

    NASA Astrophysics Data System (ADS)

    Nelson, David A.; Curran, Allen R.; Nyberg, Hans A.; Marttila, Eric A.; Mason, Patrick A.; Ziriax, John M.

    2013-03-01

    Human exposure to radio frequency (RF) electromagnetic energy is known to result in tissue heating and can raise temperatures substantially in some situations. Standards for safe exposure to RF do not reflect bio-heat transfer considerations however. Thermoregulatory function (vasodilation, sweating) may mitigate RF heating effects in some environments and exposure scenarios. Conversely, a combination of an extreme environment (high temperature, high humidity), high activity levels and thermally insulating garments may exacerbate RF exposure and pose a risk of unsafe temperature elevation, even for power densities which might be acceptable in a normothermic environment. A high-resolution thermophysiological model, incorporating a heterogeneous tissue model of a seated adult has been developed and used to replicate a series of whole-body exposures at a frequency (100 MHz) which approximates that of human whole-body resonance. Exposures were simulated at three power densities (4, 6 and 8 mW cm-2) plus a sham exposure and at three different ambient temperatures (24, 28 and 31 °C). The maximum hypothalamic temperature increase over the course of a 45 min exposure was 0.28 °C and occurred in the most extreme conditions (Tamb = 31 °C, PD = 8 mW cm-2). Skin temperature increases attributable to RF exposure were modest, with the exception of a ‘hot spot’ in the vicinity of the ankle where skin temperatures exceeded 39 °C. Temperature increases in internal organs and tissues were small, except for connective tissue and bone in the lower leg and foot. Temperature elevation also was noted in the spinal cord, consistent with a hot spot previously identified in the literature.

  18. Experimental Study of RF Sheath Formation on a Fast Wave Antenna and Limiter in the LAPD

    NASA Astrophysics Data System (ADS)

    Martin, Michael; Gekelman, Walter; Pribyl, Patrick; van Compernolle, Bart; Carter, Troy

    2015-11-01

    Ion cyclotron resonance heating (ICRH) will be an essential component of heating power in ITER. During ICRH, radio frequency (RF) sheaths may form both at the exciting antenna and further away, e.g. in the divertor region, and may cause wall material sputtering and decreased RF power coupling to the plasma. It is important to do detailed laboratory experiments that fully diagnose the sheaths and wave fields. This is not possible in fusion devices. A new RF system has recently been constructed for performing such studies in the LAPD plasma column (ne ~1012 -1013cm-3 , Te ~ 1 - 10 eV ,B0 ~ 400 - 2000 G , diameter ~ 60cm , length ~ 18 m) . The RF system is capable of pulsing at the 1 Hz rep. rate of the LAPD plasma and operating between 2-6 MHz (1st - 9th harmonic of fci in H) with a power output of 200 kW. First results of this system driving a single-strap fast wave antenna will be presented. Emissive and Langmuir probe measurements in the vicinity of both the antenna and a remote limiter and wave coupling measured by magnetic pickup loops will be presented.

  19. Introduction to Latest RF ATE with Low Test Cost Solutions

    NASA Astrophysics Data System (ADS)

    Kimishima, Masayuki

    This paper describes latest RF Automated Test Equipment (RF ATE) technologies that include device under test (DUT) connections, a calibration method, and an RF test module mainly focusing on low cost of test (COT). Most important respect for low COT is how achieve a number of simultaneous measurements and short test time as well as a plain calibration. We realized these respects by a newly proposed calibration method and a drastically downsized RF test module with multiple resources and high throughput. The calibration method is very convenient for RF ATE. Major contribution for downsizing of the RF test module is RF circuit technology in form of RF functional system in package (RF-SIPs), resulting in very attractive test solutions.

  20. Modeling of rf-assisted helicity injection start-up and current drive

    NASA Astrophysics Data System (ADS)

    Hwang, Y. S.; Ono, M.

    1994-10-01

    DC-helicity injection has been successfully applied to the tokamak start-up on CDX-U and CCT tokamaks. Furthermore, CDX-U achieved plasma current levels of up to 10 kA from zero without any ohmic drive. Helicity balance and scaling from CDX-U experiments indicate that plasma current scales with the electron temperature as Te3/2 and it is relatively insensitive to the plasma density. RF heating methods such as electron cyclotron and fast wave heating can be utilized to increase driven plasma current by reducing plasma resistivity. Zero-dimensional modeling has been attempted to design non-inductive start-up and current drive scenarios by combining helicity injection and various RF heating schemes. Plasma current can be driven from zero current by helicity injection and equilibrium field control, and then maintained by helicity injection and bootstrap current with the help of appropriate RF heating to reduce plasma resistivity. Non-inductive start-up and current drive for a 1 MA plasma current in a low-aspect-ratio geometry have been predicted with this model. In a reactor regime, 20 MA of plasma current can be driven and maintained non-inductively with a relatively high efficiency as well.

  1. A perspective on RF vacuum electronics: Innovations and recent advances

    SciTech Connect

    Parker, R.K.

    1995-12-31

    Vacuum electronics continues as a vital technology for the generation of coherent radiation in a spectral region extending from the UHF to the infrared. The veritable explosion in this field that occurred in the 1950s and the early 1960s established an effective microwave power tube technology that remains as the basic building block for a wide range of RF transmission and power applications. Drawing on ideas and techniques from relativistic and pulsed power electronics, a resurgence in research began in the mid-1970s that resulted in new capabilities at high frequency and extreme levels of peak power. More recently, solid-state and vacuum electronic interests have converged to create a new technology, vacuum micro-electronics, that promises to yield competitive new products at lower frequency and more moderate power. Many of the advances and innovations from current R and D efforts are associated with two primary technological thrusts. First is the continuing development of fast-wave device concepts for use in heating, particle accelerations, and RF power transmission. The second thrust is defined by the creative blending of solid-state and vacuum concepts, techniques and capabilities. The microwave power module, a new transmitter archetype, highlights the benefits of this approach.

  2. RF H and CD systems for DEMO - Challenges and opportunities

    SciTech Connect

    Franke, T.; Wenninger, R.; Barbato, E.; Cardinali, A.; Cesario, R.; Mirizzi, F.; Tuccillo, A. A.; Ceccuzzi, S.; Eester, D. V.; Lerche, E.

    2014-02-12

    The aim of driving a sufficient amount of plasma current with an appropriate radial current density profile is considered as one of the key challenges for a tokamak fusion power plant in steady state operation. Furthermore, efficient heating to enable transition to regime of enhanced confinement and to achieve breakeven plasma temperatures as well as MHD control and plasma breakdown assistance are required. In the framework of the EFDA Power Plant Physics and Technology (PPPT) activities, the ability of the Electron cyclotron (EC), Ion Cyclotron (IC) and Lower Hybrid (LH) systems to fulfil these requirements, was studied for a demonstration fusion power plant (DEMO). As boundary condition, a 1D description of the plasma for a pulsed DEMO based on system code studies combined with transport analysis was developed. The predicted 1D plasma parameters were used to calculate the current drive (CD) efficiency of each system and eventually optimised it. As an example, the EC current drive efficiency could be increased strongly by top launch compared to equatorial launch at least by a factor of two. For the IC system, two possible windows of operation for standard and higher frequencies were highlighted, whereby again top launch leads to higher CD-efficiencies. The efficiencies predicted for DEMO for the RF current drive systems will be presented. Finally, gaps in the feasibility of RF systems under DEMO relevant conditions will be identified.

  3. RF atmospheric plasma jet surface treatment of paper

    NASA Astrophysics Data System (ADS)

    Pawlat, Joanna; Terebun, Piotr; Kwiatkowski, Michał; Diatczyk, Jaroslaw

    2016-09-01

    A radio frequency RF atmospheric pressure plasma jet was used to enhance the wettability of cellulose-based paper of 90 g m-2 and 160 g m-2 grammage as a perspective platform for antibiotic sensitivity tests. Helium and argon were the carrier gases for oxygen and nitrogen; pure water and rapeseed oil were used for goniometric tests. The influence of the flow rate and gas type, the power of the discharge, and distance from the nozzle was examined. The surface structure was observed using an optical microscope. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectra were investigated in order to determine whether cellulose degradation processes occurred. The RF plasma jet allowed us to decrease the surface contact angle without drastic changes in other features of the tested material. Experiments confirmed the significant influence of the distance between the treated sample and reactor nozzle, especially for treatment times longer than 15 s due to the greater concentration of reactive species at the surface of the sample, which decreases with distance—and their accumulation effect with time. The increase of discharge power plays an important role in decreasing the surface contact angle for times longer than 10 s. Higher power had a positive effect on the amount of generated active particles and facilitated the ignition of discharge. However, a too high value can cause a rise in temperature of the material and heat-caused damage.

  4. Sintering of ceramics using low frequency rf power

    SciTech Connect

    Caughman, J.B.O.; Hoffman, D.J.; Baity, F.W.; Akerman, M.A.; Forrester, S.C.; Kass, M.D.

    1995-07-01

    Sintering with low frequency rf power ({approximately}50 MHz) is a new technique with unique capabilities that has been used to sinter a variety of ceramic materials, including zirconia-toughened alumina, alumina, silicon carbide, and boron carbide. Processing with low frequencies offers many advantages compared to processing with conventional microwave frequencies (915 MHz and 2.45 GHz). Because of the longer wavelength, the rf electric field penetrates materials more than microwaves. This effect allows the processing of a wider variety of materials and allows for an increase in the physical size of the material being processed. In addition, the material is heated in a single mode cavity with a uniform electric field, which reduces the occurrence of hot-spot generation and thermal runaway effects. This technique has been used to sinter large crack-free alumina samples (3 inch square) to > 97% density. The sintering and/or annealing of a number of carbide materials has been demonstrated as well, including silicon carbide, boron carbide, tungsten carbide, and titanium carbide.

  5. Laboratory-scale uranium RF plasma confinement experiments

    NASA Technical Reports Server (NTRS)

    Roman, W. C.

    1976-01-01

    An experimental investigation was conducted using 80 kW and 1.2 MW RF induction heater facilities to aid in developing the technology necessary for designing a self-critical fissioning uranium plasma core reactor. Pure uranium hexafluoride (UF6) was injected into argon-confined, steady-state, RF-heated plasmas in different uranium plasma confinement tests to investigate the characteristics of plamas core nuclear reactors. The objectives were: (1) to confine as high a density of uranium vapor as possible within the plasma while simultaneously minimizing the uranium compound wall deposition; (2) to develop and test materials and handling techniques suitable for use with high-temperature, high-pressure gaseous UF6; and (3) to develop complementary diagnostic instrumentation and measurement techniques to characterize the uranium plasma and residue deposited on the test chamber components. In all tests, the plasma was a fluid-mechanically-confined vortex-type contained within a fused-silica cylindrical test chamber. The test chamber peripheral wall was 5.7 cm ID by 10 cm long.

  6. RF atmospheric plasma jet surface treatment of paper

    NASA Astrophysics Data System (ADS)

    Pawlat, Joanna; Terebun, Piotr; Kwiatkowski, Michał; Diatczyk, Jaroslaw

    2016-09-01

    A radio frequency RF atmospheric pressure plasma jet was used to enhance the wettability of cellulose-based paper of 90 g m‑2 and 160 g m‑2 grammage as a perspective platform for antibiotic sensitivity tests. Helium and argon were the carrier gases for oxygen and nitrogen; pure water and rapeseed oil were used for goniometric tests. The influence of the flow rate and gas type, the power of the discharge, and distance from the nozzle was examined. The surface structure was observed using an optical microscope. Attenuated total reflection Fourier transform infrared (ATR–FTIR) spectra were investigated in order to determine whether cellulose degradation processes occurred. The RF plasma jet allowed us to decrease the surface contact angle without drastic changes in other features of the tested material. Experiments confirmed the significant influence of the distance between the treated sample and reactor nozzle, especially for treatment times longer than 15 s due to the greater concentration of reactive species at the surface of the sample, which decreases with distance—and their accumulation effect with time. The increase of discharge power plays an important role in decreasing the surface contact angle for times longer than 10 s. Higher power had a positive effect on the amount of generated active particles and facilitated the ignition of discharge. However, a too high value can cause a rise in temperature of the material and heat-caused damage.

  7. Steady-state operation of a large-area high-power RF ion source for the neutral beam injector

    NASA Astrophysics Data System (ADS)

    Chang, Doo-Hee; Park, Min; Jeong, Seung Ho; Kim, Tae-Seong; Lee, Kwang Won; In, Sang Ryul

    2014-10-01

    A large-area high-power RF-driven ion source is being developed in Germany for the heating and current drive (H&CD) of an ITER device. Negative hydrogen ion sources are the major components of neutral beam injection systems in future large-scale fusion devices such as an the ITER and the DEMO. The first and the second long-pulse ion sources (LPIS-1 and LPIS-2) have been successfully developed with a magnetic-bucket plasma generator, including a filament heating structure for the first NBI (NBI-1) system of the KSTAR tokamak. A development plan exists for a large-area high-power RF ion source for steady-state operation (more than 300 seconds) at the Korea Atomic Energy Research Institute (KAERI) to extract positive ions, which can be used for the NBI heating and current drive systems, and to extract negative ions for future fusion devices such as a Fusion Neutron Source and Korea — DEMO. The RF ion source consists of a driver region, including a helical antenna and a discharge chamber, and an expansion region (magnetic bucket of the prototype LPIS-1). RF power can be transferred at up to 10 kW with a fixed frequency of 2 MHz through an optimized RF matching system. An actively water-cooled Faraday shield is located inside the driver region of the ion source for stable and steady-state operation of the RF discharge. The uniformities of the plasma parameters are measured at the lowest area of the expansion bucket by using two RF-compensated electrostatic probes along the directions of the short and the long dimensions of the expansion region.

  8. Abnormal heating of low-energy electrons in low-pressure capacitively coupled discharges.

    PubMed

    Park, G Y; You, S J; Iza, F; Lee, J K

    2007-02-23

    In low-pressure capacitively coupled plasmas, high-energy electrons are collisionlessly heated by large rf fields in the sheaths while low-energy electrons are confined in the bulk plasma by the ambipolar potential. Low-energy electrons are typically inefficiently heated due to their low collisionality and the weak rf electric field present in the bulk. It is shown, however, that as a result of the nonlinear interaction between the electron motion and the weak rf field present in the bulk, low-energy electrons can be efficiently heated. Electrons in the bulk that bounce inside the electrostatic potential well with a frequency equal to the rf excitation frequency are efficiently heated by the coherent interaction with the rf field. This resonant collisionless heating can be very efficient and manifest itself as a plateau in the electron energy probability function.

  9. Rf capacitively-coupled electrodeless light source

    DOEpatents

    Manos, Dennis M.; Diggs, Jessie; Ametepe, Joseph D.; Fugitt, Jock A.

    2000-01-01

    An rf capacitively-coupled electrodeless light source is provided. The light source comprises a hollow, elongated chamber and at least one center conductor disposed within the hollow, elongated chamber. A portion of each center conductor extends beyond the hollow, elongated chamber. At least one gas capable of forming an electronically excited molecular state is contained within each center conductor. An electrical coupler is positioned concentric to the hollow, elongated chamber and the electrical coupler surrounds the portion of each center conductor that extends beyond the hollow, elongated chamber. A rf-power supply is positioned in an operable relationship to the electrical coupler and an impedance matching network is positioned in an operable relationship to the rf power supply and the electrical coupler.

  10. RF Spectroscopy on a Homogeneous Fermi Gas

    NASA Astrophysics Data System (ADS)

    Yan, Zhenjie; Mukherjee, Biswaroop; Patel, Parth; Struck, Julian; Zwierlein, Martin

    2016-05-01

    Over the last two decades RF spectroscopy has been established as an indispensable tool to probe a large variety of fundamental properties of strongly interacting Fermi gases. This ranges from measurement of the pairing gap over tan's contact to the quasi-particle weight of Fermi polarons. So far, most RF spectroscopy experiments have been performed in harmonic traps, resulting in an averaged response over different densities. We have realized an optical uniform potential for ultracold Fermi gases of 6 Li atoms, which allows us to avoid the usual problems connected to inhomogeneous systems. Here we present recent results on RF spectroscopy of these homogeneous samples with a high signal to noise ratio. In addition, we report progress on measuring the contact of a unitary Fermi gas across the normal to superfluid transition.

  11. X-Band RF Gun Development

    SciTech Connect

    Vlieks, Arnold; Dolgashev, Valery; Tantawi, Sami; Anderson, Scott; Hartemann, Fred; Marsh, Roark; /LLNL, Livermore

    2012-06-22

    In support of the MEGa-ray program at LLNL and the High Gradient research program at SLAC, a new X-band multi-cell RF gun is being developed. This gun, similar to earlier guns developed at SLAC for Compton X-ray source program, will be a standing wave structure made of 5.5 cells operating in the pi mode with copper cathode. This gun was designed following criteria used to build SLAC X-band high gradient accelerating structures. It is anticipated that this gun will operate with surface electric fields on the cathode of 200 MeV/m with low breakdown rate. RF will be coupled into the structure through a final cell with symmetric duel feeds and with a shape optimized to minimize quadrupole field components. In addition, geometry changes to the original gun, operated with Compton X-ray source, will include a wider RF mode separation, reduced surface electric and magnetic fields.

  12. RF-Based Accelerators for HEDP Research

    SciTech Connect

    Staples, John W.; Sessler, Andrew; Keller, Roderich; Ostroumov,Petr; Chou, Weiren

    2005-05-09

    Accelerator-driven High-Energy Density Physics (HEDP) experiments require typically 1 nanosecond, 1 microcoulomb pulses of mass 20 ions accelerated to several MeV to produce eV-level excitations in thin targets, the warm dense matter regime. Traditionally the province of induction linacs, RF-based acceleration may be a viable alternative with recent breakthroughs in accelerating structures and high-field compact superconducting solenoids. A reference design for an RF-based accelerator for HEDP research is presented using 15 T solenoids and multiple-gap RF structures configured with multiple parallel beams combined at the target. The beam is ballistically compressed with an induction linac core providing the necessary energy sweep and injected into a plasma-neutralized drift compression channel resulting in a 1 mm radius beam spot 1 nanosecond long at a thin foil or low-density target.

  13. Prospects for Advanced RF Theory and Modeling

    SciTech Connect

    Batchelor, D.B.

    1999-04-12

    This paper represents an attempt to express in print the contents of a rather philosophical review talk. The charge for the talk was not to summarize the present status of the field and what we can do, but to assess what we will need to do in the future and where the gaps are in fulfilling these needs. The objective was to be complete, covering all aspects of theory and modeling in all frequency regimes, although in the end the talk mainly focussed on the ion cyclotron range of frequencies (ICRF). In choosing which areas to develop, it is important to keep in mind who the customers for RF modeling are likely to be and what sorts of tasks they will need for RF to do. This occupies the first part of the paper. Then we examine each of the elements of a complete RF theory and try to identify the kinds of advances needed.

  14. Laser/rf personnel identification system

    NASA Astrophysics Data System (ADS)

    Zari, Michael C.; Ward, Reeder N.; Hess, David A.; Anderson, Christopher S.

    1995-05-01

    This paper documents the design of a Laser/RF Personnel Identification System developed for the US Army Communications and Electronics Command (CECOM) for soldier identification. The system has dual use applications, including law enforcement officer protection, and includes a laser interrogation unit with a programmable activation code. The interrogation unit is very directive for low probability of intercept (LPI), which is of interest during covert operations. A responder unit, worn by the law enforcement personnel or soldier, transmits an LPI radio frequency (RF) response only after receiving the proper interrogation code. The basic subsystems for the identification system are a laser interrogation unit, an RF responder unit, and a programming/synchronization unit. In this paper, the operating principles for the subsystems are reviewed and design issues are discussed. In addition to the design performed for CECOM, a breadboard system was developed to validate the concept. Hardware implementation is reviewed and field testing of the breadboard is presented.

  15. Pulsed rf superconductivity program at SLAC

    SciTech Connect

    Campisi, I.E.; Farkas, Z.D.

    1984-08-01

    Recent tests performed at SLAC on superconducting TM/sub 010/ caavities using short rf pulses (less than or equal to 2.5 ..mu..s) have established that at the cavity surface magnetic fields can be reached in the vicinity of the theoretical critical fields without an appreciable increase in average losses. Tests on niobium and lead cavities are reported. The pulse method seems to be best suited to study peak field properties of superconductors in the microwave band, without the limitations imposed by defects. The short pulses also seem to be more effective in decreasing the causes of field emission by rf processing. Applications of the pulsed rf superconductivity to high-gradient linear accelerators are also possible.

  16. THERMAL MODELING OF ION EXCHANGE COLUMNS WITH SPHERICAL RF RESIN

    SciTech Connect

    Lee, S.; King, W.

    2009-12-30

    Models have been developed to simulate the thermal performance of RF columns fully loaded with radioactive cesium. Temperature distributions and maximum temperatures across the column were calculated during Small Column Ion Exchange (SCIX) process upset conditions with a focus on implementation at Hanford. A two-dimensional computational modeling approach was taken to include conservative, bounding estimates for key parameters such that the results will provide the maximum centerline temperatures achievable under the design configurations using a feed composition known to promote high cesium loading on RF. The current full-scale design for the SCIX system includes a central cooling tube, and one objective of these calculations was to examine its elimination to simplify the design. Results confirmed that a column design without a central cooling tube is feasible for RF, allowing for the possibility of significant design simplifications if it can be assumed that the columns are always filled with liquid. With active cooling through the four outer tubes, the maximum column diameter expected to maintain the temperature below the assumed media and safety limits is 26 inches, which is comparable to the current design diameter. Additional analysis was conducted to predict the maximum column temperatures for the previously unevaluated accident scenario involving inadvertent drainage of liquid from a cesium-saturated column, with retention of the ion exchange media and cesium in the column. As expected, much higher maximum temperatures are observed in this case due to the poor heat transfer properties of air versus liquid. For this hypothetical accident scenario involving inadvertent and complete drainage of liquid from a cesium-saturated column, the modeling results indicate that the maximum temperature within a 28 inch diameter RF column with external cooling is expected to exceed 250 C within 2 days, while the maximum temperature of a 12 inch column is maintained below

  17. SSRL photocathode RF gun test stand

    SciTech Connect

    Hernandez, M.; Baltay, M.; Boyce, A.

    1995-12-31

    A photocathode RF gun test stand designed for the production and study of high brightness electron beams will be constructed at SSRL. The beam will be generated from a laser driven third generation photocathode RF gun being developed in collaboration with BNL, LBL, and UCLA. The 3-5 [MeV] beam from the gun will be accelerated using a SLAC three meter S-band accelerator section, in order to achieve the desired low emittance beam, emittance compensation with solenoidal focusing will be employed.

  18. Potential-well distortion in barrier Rf

    SciTech Connect

    King Ng

    2004-04-29

    Head-tail asymmetry has been observed in the longitudinal beam profiles in the Fermilab Recycler Ring where protons or antiprotons are stored in rf barrier buckets. The asymmetry is caused by the distortion of the rf potential well in the presence of resistive impedance. Gaussian energy distribution can fit the observed asymmetric beam profile but not without discrepancy. It can also fit the measured energy distribution. On the other hand, generalized elliptic distribution gives a better fit to the beam profile. However, it fails to reproduce the observed energy distribution.

  19. RF Driven Multicusp H- Ion Source

    SciTech Connect

    Leung, K.N.; DeVries, G.J.; DiVergilio, W.F.; Hamm, R.W.; Hauck, C.A.; Kunkel, W.B.; McDonald, D.S.; Williams, M.D.

    1990-06-01

    An rf driven multicusp source capable of generating 1-ms H{sup -} beam pulses with a repetition rate as high as 150 Hz has been developed. This source can be operated with a filament or other types of starter. There is almost no lifetime limitation and a clean plasma can be maintained for a long period of operation. It is demonstrated that rf power as high as 25 kW could be coupled inductively to the plasma via a glass-coated copper-coil antenna. The extracted H{sup -} current density achieved is about 200 mA/cm{sup 2}.

  20. National RF Test Facility as a multipurpose development tool

    SciTech Connect

    McManamy, T.J.; Becraft, W.R.; Berry, L.A.; Blue, C.W.; Gardner, W.L.; Haselton, H.H.; Hoffman, D.J.; Loring, C.M. Jr.; Moeller, F.A.; Ponte, N.S.

    1983-01-01

    Additions and modifications to the National RF Test Facility design have been made that (1) focus its use for technology development for future large systems in the ion cyclotron range of frequencies (ICRF), (2) expand its applicability to technology development in the electron cyclotron range of frequencies (ECRF) at 60 GHz, (3) provide a facility for ELMO Bumpy Torus (EBT) 60-GHz ring physics studies, and (4) permit engineering studies of steady-state plasma systems, including superconducting magnet performance, vacuum vessel heat flux removal, and microwave protection. The facility will continue to function as a test bed for generic technology developments for ICRF and the lower hybrid range of frequencies (LHRF). The upgraded facility is also suitable for mirror halo physics experiments.

  1. Detailing Radio Frequency Heating Induced by Coronary Stents: A 7.0 Tesla Magnetic Resonance Study

    PubMed Central

    Santoro, Davide; Winter, Lukas; Müller, Alexander; Vogt, Julia; Renz, Wolfgang; Özerdem, Celal; Grässl, Andreas; Tkachenko, Valeriy; Schulz-Menger, Jeanette; Niendorf, Thoralf

    2012-01-01

    The sensitivity gain of ultrahigh field Magnetic Resonance (UHF-MR) holds the promise to enhance spatial and temporal resolution. Such improvements could be beneficial for cardiovascular MR. However, intracoronary stents used for treatment of coronary artery disease are currently considered to be contra-indications for UHF-MR. The antenna effect induced by a stent together with RF wavelength shortening could increase local radiofrequency (RF) power deposition at 7.0 T and bears the potential to induce local heating, which might cause tissue damage. Realizing these constraints, this work examines RF heating effects of stents using electro-magnetic field (EMF) simulations and phantoms with properties that mimic myocardium. For this purpose, RF power deposition that exceeds the clinical limits was induced by a dedicated birdcage coil. Fiber optic probes and MR thermometry were applied for temperature monitoring using agarose phantoms containing copper tubes or coronary stents. The results demonstrate an agreement between RF heating induced temperature changes derived from EMF simulations versus MR thermometry. The birdcage coil tailored for RF heating was capable of irradiating power exceeding the specific-absorption rate (SAR) limits defined by the IEC guidelines by a factor of three. This setup afforded RF induced temperature changes up to +27 K in a reference phantom. The maximum extra temperature increase, induced by a copper tube or a coronary stent was less than 3 K. The coronary stents examined showed an RF heating behavior similar to a copper tube. Our results suggest that, if IEC guidelines for local/global SAR are followed, the extra RF heating induced in myocardial tissue by stents may not be significant versus the baseline heating induced by the energy deposited by a tailored cardiac transmit RF coil at 7.0 T, and may be smaller if not insignificant than the extra RF heating observed under the circumstances used in this study. PMID:23185498

  2. Development of system level integration of compact RF components on multilayer liquid crystal polymer (LCP)

    NASA Astrophysics Data System (ADS)

    Chung, David

    The objective of this research is to optimize compactness for reconfigurable wireless communication systems by integrating Radio Frequency (RF) components on a multilayer Liquid Crystal Polymer (LCP) package while minimizing the size and interconnection of each component. To achieve this goal, various RF/microwave components have been integrated on LCP with the design, fabrication, and testing results to explore the feasibility of the designs for RF applications. The first chapter of this research focuses on the characterization of via interconnects for 3D system designs. As a crucial component for achieving compact multilayer designs, various transition designs are explored from DC to 110 GHz. In particular, High Density Interconnects (HDI) are investigated to achieve low loss performance at mm-wave frequencies. An example of accessing the input and output of a LCP packaged device using via interconnects is included. In addition, a heat sink using via technology is presented for active cooling of heat generating embedded devices. Chapters 3, 4, and 5 demonstrate the results of RF Micro-Electro-Mechanical Systems (MEMS) switches integrated on LCP to create compact reconfigurable devices. RF MEMS switches are essential for designing compact multi-functional devices. A pattern reconfigurable antenna with monolithically integrated RF MEMS switches is presented. In addition, a compact 3D phase shifter using RF MEMS switches for a 2 x 2 phased antenna array is also presented in this work. To create a phased antenna array that is more compatible with Integrated Circuits (IC), Lead Zirconate Titanate (PZT) RF MEMS switches are used to make a low voltage phase shifter. The actuation voltage is under 10 V, which is more easily achievable in a integrated system compared to commonly used electrostatic actuated RF MEMS switches that required at least 30 V. In Chapter 6, an expandable, low cost, and conformal multilayer phased antenna array is presented. Starting with a 4 x 8

  3. Superconducting RF Technology R&D for Future Accelerator Applications

    SciTech Connect

    Reece, Charles E.; Ciovati, Gianluigi

    2012-09-01

    Superconducting rf (SRF) technology is evolving rapidly, as are its applications. While there is active exploitation of what one may call the current state-of-the-practice, there is also rapid progress in expanding in several dimensions the accessible and useful parameter space. While state-of-the-art performance sometimes outpaces thorough understanding, the improving scientific understanding from active SRF research is clarifying routes to obtain optimum performance from present materials and opening avenues beyond the standard bulk niobium. The improving technical basis understanding is enabling process engineering to improve both performance confidence and reliability and also unit implementation costs. Increasing confidence in the technology enables the engineering of new creative application designs. We attempt to survey this landscape to highlight the potential for future accelerator applications.

  4. Thermal Considerations of Space Solar Power Concepts with 3.5 GW RF Output

    NASA Technical Reports Server (NTRS)

    Choi, Michael K.

    2000-01-01

    This paper presents the thermal challenge of the Space Solar Power (SSP) design concepts with a 3.5 GW radio-frequency (RF) output. High efficiency klystrons are thermally more favored than solid state (butterstick) to convert direct current (DC) electricity to radio-frequency (RF) energy at the transmitters in these concepts. Using klystrons, the heat dissipation is 0.72 GW. Using solid state, the heat dissipation is 2.33 GW. The heat dissipation of the klystrons is 85% at 500C, 10% at 300C, and 5% at 125C. All the heat dissipation of the solid state is at 100C. Using klystrons, the radiator area is 74,500 square m Using solid state, the radiator area is 2,362,200 square m Space constructable heat pipe radiators are assumed in the thermal analysis. Also, to make the SSP concepts feasible, the mass of the heat transport system must be minimized. The heat transport distance from the transmitters to the radiators must be minimized. It can be accomplished by dividing the radiator into a cluster of small radiators, so that the heat transport distances between the klystrons and radiators can be minimized. The area of each small radiator is on the order of 1 square m. Two concepts for accommodating a cluster of small radiators are presented. If the distance between the transmitters and radiators is 1.5 m or less, constant conductance heat pipes (CCHPs) are acceptable for heat transport. If the distance exceeds 1.5 m, loop heat pipes (LHPs) are needed.

  5. 47 CFR 101.1425 - RF safety.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false RF safety. 101.1425 Section 101.1425 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE... rules for radiation hazards, as set forth in § 1.1307 of this chapter....

  6. 47 CFR 101.1425 - RF safety.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false RF safety. 101.1425 Section 101.1425 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE... rules for radiation hazards, as set forth in § 1.1307 of this chapter....

  7. 47 CFR 101.1425 - RF safety.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false RF safety. 101.1425 Section 101.1425 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE... rules for radiation hazards, as set forth in § 1.1307 of this chapter....

  8. RF Breakdown of Metallic Surfaces in Hydrogen

    SciTech Connect

    BastaniNejad, M.; Elmustafa, A.A.; Yonehara, K.; Chung, M.; Jansson, A.; Hu, M.; Moretti, A.; Popovic, M.; Alsharo'a, M.; Neubauer, M.; Sah, R.; /Muons Inc., Batavia

    2009-05-01

    In earlier reports, microscopic images of the surfaces of metallic electrodes used in high-pressure gas-filled 805 MHz RF cavity experiments were used to investigate the mechanism of RF breakdown of tungsten, molybdenum, and beryllium electrode surfaces. Plots of remnants were consistent with the breakdown events being due to field emission, due to the quantum mechanical tunnelling of electrons through a barrier as described by Fowler and Nordheim. In the work described here, these studies have been extended to include tin, aluminium, and copper. Contamination of the surfaces, discovered after the experiments concluded, have cast some doubt on the proper qualities to assign to the metallic surfaces. However, two significant results are noted. First, the maximum stable RF gradient of contaminated copper electrodes is higher than for a clean surface. Second, the addition of as little as 0.01% of SF6 to the hydrogen gas increased the maximum stable gradient, which implies that models of RF breakdown in hydrogen gas will be important to the study of metallic breakdown.

  9. NSLS-II RF BEAM POSITION MONITOR

    SciTech Connect

    Vetter, K.; Della Penna, A. J.; DeLong, J.; Kosciuk, B.; Mead, J.; Pinayev, I.; Singh, O.; Tian, Y.; Ha, K.; Portmann, G.; Sebek J.

    2011-03-28

    An internal R&D program has been undertaken at BNL to develop a sub-micron RF Beam Position Monitor (BPM) for the NSLS-II 3rd generation light source that is currently under construction. The BPM R&D program started in August 2009. Successful beam tests were conducted 15 months from the start of the program. The NSLS-II RF BPM has been designed to meet all requirements for the NSLS-II Injection system and Storage Ring. Housing of the RF BPM's in +-0.1 C thermally controlled racks provide sub-micron stabilization without active correction. An active pilot-tone has been incorporated to aid long-term (8hr min) stabilization to 200nm RMS. The development of a sub-micron BPM for the NSLS-II has successfully demonstrated performance and stability. Pilot Tone calibration combiner and RF synthesizer has been implemented and algorithm development is underway. The program is currently on schedule to start production development of 60 Injection BPM's starting in the Fall of 2011. The production of {approx}250 Storage Ring BPM's will overlap the Injection schedule.

  10. RF Design of the LCLS Gun

    SciTech Connect

    Limborg-Deprey, C

    2010-12-13

    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.

  11. Image reconstructions with the rotating RF coil

    NASA Astrophysics Data System (ADS)

    Trakic, A.; Wang, H.; Weber, E.; Li, B. K.; Poole, M.; Liu, F.; Crozier, S.

    2009-12-01

    Recent studies have shown that rotating a single RF transceive coil (RRFC) provides a uniform coverage of the object and brings a number of hardware advantages (i.e. requires only one RF channel, averts coil-coil coupling interactions and facilitates large-scale multi-nuclear imaging). Motion of the RF coil sensitivity profile however violates the standard Fourier Transform definition of a time-invariant signal, and the images reconstructed in this conventional manner can be degraded by ghosting artifacts. To overcome this problem, this paper presents Time Division Multiplexed — Sensitivity Encoding (TDM-SENSE), as a new image reconstruction scheme that exploits the rotation of the RF coil sensitivity profile to facilitate ghost-free image reconstructions and reductions in image acquisition time. A transceive RRFC system for head imaging at 2 Tesla was constructed and applied in a number of in vivo experiments. In this initial study, alias-free head images were obtained in half the usual scan time. It is hoped that new sequences and methods will be developed by taking advantage of coil motion.

  12. Advanced RF power sources for linacs

    SciTech Connect

    Wilson, P.B.

    1996-10-01

    In order to maintain a reasonable over-all length at high center-of-mass energy, the main linac of an electron-positron linear collider must operate at a high accelerating gradient. For copper (non-superconducting) accelerator structures, this implies a high peak power per unit length and a high peak power per RF source, assuming a limited number of discrete sources are used. To provide this power, a number of devices are currently under active development or conceptual consideration: conventional klystrons with multi-cavity output structures, gyroklystrons, magnicons, sheet-beam klystrons, multiple-beam klystrons and amplifiers based on the FEL principle. To enhance the peak power produced by an rf source, the SLED rf pulse compression scheme is currently in use on existing linacs, and new compression methods that produce a flatter output pulse are being considered for future linear colliders. This paper covers the present status and future outlook for the more important rf power sources and pulse compression systems. It should be noted that high gradient electron linacs have applications in addition to high-energy linear colliders; they can, for example, serve as compact injectors for FEL`s and storage rings.

  13. The IPNS second harmonic RF upgrade.

    SciTech Connect

    Middendorf, M. E.; Brumwell, F. R.; Dooling, J. C.; Horan, D.; Kustom, R. L.; Lien, M. K.; McMichael, G. E.; Moser, M. R.; Nassiri, A.; Wang, S.; Accelerator Systems Division

    2008-01-01

    The intense pulsed neutron source (IPNS) rapid cycling synchrotron (RCS) is used to accelerate protons from 50 MeV to 450 MeV, at a repetition rate of 30 Hz. The original ring design included two identical rf systems, each consisting of an accelerating cavity, cavity bias supply, power amplifiers and low-level analog electronics. The original cavities are located 180 degrees apart in the ring and provide a total peak accelerating voltage of {approx}21 kV over the 2.21-MHz to 5.14-MHz revolution frequency sweep. A third rf system has been constructed and installed in the RCS. The third rf system is capable of operating at the fundamental revolution frequency for the entire acceleration cycle, providing an additional peak accelerating voltage of up to {approx}11 kV, or at the second harmonic of the revolution frequency for the first {approx}4 ms of the acceleration cycle, providing an additional peak voltage of up to {approx}11 kV for bunch shape control. We describe here the hardware implementation and operation to date of the third rf cavity in the second harmonic mode.

  14. 47 CFR 101.1425 - RF safety.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false RF safety. 101.1425 Section 101.1425 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE... rules for radiation hazards, as set forth in § 1.1307 of this chapter....

  15. 47 CFR 101.1425 - RF safety.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false RF safety. 101.1425 Section 101.1425 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE... rules for radiation hazards, as set forth in § 1.1307 of this chapter....

  16. Three-dimensional RF structure calculations

    NASA Astrophysics Data System (ADS)

    Cooper, R. K.; Browman, M. J.; Weiland, T.

    1989-04-01

    The calculation of three-dimensional rf structures is rapidly approaching adolescence, after having been in its infancy for the last four years. This paper will show the kinds of calculations that are currently being performed in the frequency domain and is a companion paper to one in which time-domain calculations are described.

  17. Three-dimensional rf structure calculations

    SciTech Connect

    Cooper, R.K.; Browman, M.J.; Weiland, T.

    1988-01-01

    The calculation of three-dimensional rf structures is rapidly approaching adolescence, after having been in its infancy for the last four years. This paper will show the kinds of calculations that are currently being performed in the frequency domain and is a companion paper to one in which time-domain calculations are described. 13 refs., 14 figs.

  18. Eccentric superconducting RF cavity separator structure

    DOEpatents

    Aggus, John R.; Giordano, Salvatore T.; Halama, Henry J.

    1976-01-01

    Accelerator apparatus having an eccentric-shaped, iris-loaded deflecting cavity for an rf separator for a high energy high momentum, charged particle accelerator beam. In one embodiment, the deflector is superconducting, and the apparatus of this invention provides simplified machining and electron beam welding techniques. Model tests have shown that the electrical characteristics provide the desired mode splitting without adverse effects.

  19. 47 CFR 95.1221 - RF exposure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false RF exposure. 95.1221 Section 95.1221 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO... operating under this section must contain a finite difference time domain (FDTD) computational...

  20. RF cavities with transversely biased ferrite tuning

    SciTech Connect

    Smythe, W.R.; Brophy, T.G.; Carlini, R.D.; Friedrichs, C.C.; Grisham, D.L.; Spalek, G.; Wilkerson, L.C.

    1985-10-01

    Earley et al. suggested that ferrite tuned rf cavities have lower ferrite power dissipation if the ferrite bias field is perpendicular rather than parallel to the rf magnetic field. A 50-84 MHz cavity has been constructed in which ferrite can be biased either way. Low power measurements of six microwave ferrites show that the magnetic Q's of these ferrites under perpendicular bias are much higher than under parallel bias, and that the high Q region extends over a much wider range of rf permeability. TDK Y-5 ferrite was found to have a magnetic Q of 10,800, 4,800, 1,200 and 129 at rf permeabilities of 1.2, 2.4, 3.7 and 4.5, respectively. Measurements of perpendicularly biased ferrite at various power levels were made in a coaxial line cavity. The Q of Y-5 ferrite was found to decrease by less than a factor of 2 as the power density in the ferrite was increased to 1.3 W/cmT. A cavity design for a 6 GeV, high current, rapid cycling synchrotron using transversely biased ferrite tuning is described.

  1. Binary rf pulse compression experiment at SLAC

    SciTech Connect

    Lavine, T.L.; Spalek, G.; Farkas, Z.D.; Menegat, A.; Miller, R.H.; Nantista, C.; Wilson, P.B.

    1990-06-01

    Using rf pulse compression it will be possible to boost the 50- to 100-MW output expected from high-power microwave tubes operating in the 10- to 20-GHz frequency range, to the 300- to 1000-MW level required by the next generation of high-gradient linacs for linear for linear colliders. A high-power X-band three-stage binary rf pulse compressor has been implemented and operated at the Stanford Linear Accelerator Center (SLAC). In each of three successive stages, the rf pulse-length is compressed by half, and the peak power is approximately doubled. The experimental results presented here have been obtained at low-power (1-kW) and high-power (15-MW) input levels in initial testing with a TWT and a klystron. Rf pulses initially 770 nsec long have been compressed to 60 nsec. Peak power gains of 1.8 per stage, and 5.5 for three stages, have been measured. This corresponds to a peak power compression efficiency of about 90% per stage, or about 70% for three stages, consistent with the individual component losses. The principle of operation of a binary pulse compressor (BPC) is described in detail elsewhere. We recently have implemented and operated at SLAC a high-power (high-vacuum) three-stage X-band BPC. First results from the high-power three-stage BPC experiment are reported here.

  2. RF Sputtering of Gold Contacts On Niobium

    NASA Technical Reports Server (NTRS)

    Barr, D. W.

    1983-01-01

    Reliable gold contacts are deposited on niobium by combination of RF sputtering and photolithography. Process results in structures having gold only where desired for electrical contact. Contacts are stable under repeated cycling from room temperature to 4.2 K and show room-temperature contact resistance as much as 40 percent below indium contacts made by thermalcompression bonding.

  3. Common Sense Copper and RF Guns

    SciTech Connect

    Mulhollan, G.

    2005-01-18

    The purpose of this document is to gather together both fundamental information on copper and on the cleaning and operation of copper in RF gun structures. While incomplete, this is a living document and will be added to and updated as necessary.

  4. Simulations of percutaneous RF ablation systems

    NASA Astrophysics Data System (ADS)

    Ryan, Thomas P.; Kwok, Jonathan; Beetel, Robert J.

    2003-06-01

    Breast and liver cancers provide an ongoing challenge in regard to treatment efficacy and successful clinical outcomes. A variety of percutaneous technology has been applied for thermal treatment of the liver and breast, including laser, microwave, cryogenic and radiofrequency (RF) devices. When simplicity and cost are factored in, RF hardware and applicators offer the most cost-effective treatment pathway by interventional radiologists and surgeons. To model percutaneous RF treatments in liver and breast, simulations were done in 3D with a finite element model. Three RF systems were modeled, including 1) single needle; 2) clustered needle, cooled and uncooled; and 3) deployable, hook electrodes. The results show the limitations of the systems in percutaneous procedures, depending on temperature limits, duration of treatment, and whether the devices are cooled or uncooled. For thermal treatment, the isotherm of 55°C was considered the margin of coagulation necrosis. The 3-D volumes of 55°C and 65°C isotherm shells aid in the selection of the best method to improve clinical outcomes, while paying attention to the size and shape of the applicator and duration of treatment.

  5. Recent developments in superconducting cavity RF control

    NASA Astrophysics Data System (ADS)

    Simrock, Stefan

    2005-02-01

    Presently a large number of superconducting accelerators under construction or proposed impose stringent requirements on the rf control of the accelerating fields, operability, and reliability. The accelerator application range from linear colliders, UV-FELs and X-FELs, ERL based light sources, high power proton accelerators to heavy ion accelerators. Examples are TESLA and NLC, the European XFEL and Lux, the Cornell ERL based light source, the high power ERL based IR-FEL at JLAB, the neutron spallation source SNS, the heavy ion accelerator RIA, and the energy upgrade of the CEBAF accelerator at JLAB. The requirements on the rf systems range from low to high current, medium to high gradient, and relativistic to non-relativistics beam. With the technology in analog and digital electronics developing rapidly, the technology for rf feedback system is changing more and more from analog or hybrid systems towards fully digital systems. Todays DSPs and FPGAs can process sophisticated feedback algorithms on a time scale of some 100 ns to a few us with ADCs and DACs with about 100 MHz bandwidth at 14 bit and latencies less than 100 ns available to inter-face to the field detectors and field control actuators. Also fast analog multiplier technology allows for field detection and actuators for rf control with high linearity, measurement and control bandwidth while maintaining low noise levels.

  6. Transparency and Coherence in rf SQUID Metamaterials

    NASA Astrophysics Data System (ADS)

    Anlage, Steven; Trepanier, Melissa; Zhang, Daimeng

    We have developed active metamaterials capable of quickly tuning their electrical and magnetic responses over a wide frequency range. These metamaterials are based on superconducting elements to form low loss, physically and electrically small, highly tunable structures for fundamental studies of extraordinarily nonlinear media. The meta-atoms are rf superconducting quantum interference devices (SQUIDs) that incorporate the Josephson effect. RF SQUIDs have an inductance which is strongly tunable with dc and rf magnetic fields and currents. The rf SQUID metamaterial is a richly nonlinear effective medium introducing qualitatively new macroscopic quantum phenomena into the metamaterials community, namely magnetic flux quantization and the Josephson effect. The coherent oscillation of the meta-atoms is strongly sensitive to the environment and measurement conditions, and we have developed several strategies to improve the coherence experimentally by exploiting ideas from nonlinear dynamics. The metamaterials also display a unique form of transparency whose development can be manipulated through multiple parametric dependences. We discuss these qualitatively new metamaterial phenomena. This work is supported by the NSF-GOALI and OISE Programs through Grant No. ECCS-1158644 and the Center for Nanophysics and Advanced Materials (CNAM).

  7. RF compensation of double Langmuir probes: modelling and experiment

    NASA Astrophysics Data System (ADS)

    Caneses, Juan F.; Blackwell, Boyd

    2015-06-01

    An analytical model describing the physics of driven floating probes has been developed to model the RF compensation of the double langmuir probe (DLP) technique. The model is based on the theory of the RF self-bias effect as described in Braithwaite’s work [1], which we extend to include time-resolved behaviour. The main contribution of this work is to allow quantitative determination of the intrinsic RF compensation of a DLP in a given RF discharge. Using these ideas, we discuss the design of RF compensated DLPs. Experimental validation for these ideas is presented and the effects of RF rectification on DLP measurements are discussed. Experimental results using RF rectified DLPs indicate that (1) whenever sheath thickness effects are important overestimation of the ion density is proportional to the level of RF rectification and suggest that (2) the electron temperature measurement is only weakly affected.

  8. Inductive current startup in large tokamaks with expanding minor radius and rf assist

    SciTech Connect

    Borowski, S.K.

    1984-02-01

    Auxiliary rf heating of electrons before and during the current-rise phase of a large tokamak, such as the Fusion Engineering Device (R = 4.8 m, a = 1.3 m, sigma = 1.6, B/sub T/ = 3.62 T), is examined as a means of reducing both the initiation loop voltage and resistive flux expenditure during startup. Prior to current initiation, 1 to 2 MW of electron cyclotron resonance heating power at approx. 90 GHz is used to create a small volume of high conductivity plasma (T/sub e/ approx. = 100 eV, n/sub e/ approx. = 10/sup 19/ m/sup -3/) near the upper hybrid resonance (UHR) region. This plasma conditioning permits a small radius (a/sub 0/ approx. = 0.2 to 0.4 m) current channel to be established with a relatively low initial loop voltage (less than or equal to 25 V as opposed to approx. 100 V without rf assist). During the subsequent plasma expansion and current ramp phase, a combination of rf heating (up to 5 MW) and current profile control leads to a substantial savings in volt-seconds by: (1) minimizing the resistive flux consumption; and (2) maintaining the internal flux at or near the flat profile limit.

  9. Interactions of release factor RF3 with the translation machinery.

    PubMed

    O'Connor, Michael

    2015-08-01

    The bacterial release factor RF3 is a GTPase that has been implicated in multiple, incompletely understood steps of protein synthesis. This study explores the genetic interaction of RF3 with other components of the translation machinery. RF3 contributes to translation termination by recycling the class I release factors RF1 and RF2 off post-termination ribosomes. RF3 has also been implicated in dissociation of peptidyl-tRNAs from elongating ribosomes and in a post-peptidyltransferase quality control (post-PT QC) mechanism that selectively terminates ribosomes carrying erroneous peptides. A majority of the in vivo studies on RF3 have been carried out in K-12 strains of Escherichia coli which carry a partially defective RF2 protein with an Ala to Thr substitution at position 246. Here, the contribution of the K-12 specific RF2 variant to RF3 activities has been investigated. Strain reconstruction experiments in both E. coli and Salmonella enterica demonstrate that defects in termination and post-PT QC that are associated with RF3 loss, as well as phenotypes uncovered by phenotypic profiling, are all substantially ameliorated when the incompletely active K-12-specific RF2 protein is replaced by a fully active Ala246 RF2. These results indicate that RF3 loss is well tolerated in bacteria with fully active class I release factors, but that many of the previously reported phenotypes for RF3 deletion strains have been compromised by the presence of a partially defective RF2. PMID:25636454

  10. A PARAMETRIC STUDY OF BCS RF SURFACE IMPEDANCE WITH MAGNETIC FIELD USING THE XIAO CODE

    SciTech Connect

    Reece, Charles E.; Xiao, Binping

    2013-09-01

    A recent new analysis of field-dependent BCS rf surface impedance based on moving Cooper pairs has been presented.[1] Using this analysis coded in Mathematica TM, survey calculations have been completed which examine the sensitivities of this surface impedance to variation of the BCS material parameters and temperature. The results present a refined description of the "best theoretical" performance available to potential applications with corresponding materials.

  11. Modulator considerations for the SNS RF system

    SciTech Connect

    Tallerico, P.J.; Reass, W.A.

    1998-12-31

    The Spallation Neutron Source (SNS) is an intense neutron source for neutron scattering experiments. The project is in the research stage, with construction funding beginning next year. The SNS is comprised of an ion source, a 1,000 MeV, H{sup {minus}} linear accelerator, an accumulator ring, a neutron producing target, and experimental area to utilize the scattering of the neutrons. The linear accelerator is RF driven, and the peak beam current is 27 mA and the beam duty factor is 5.84%. The peak RF power required is 104 MW, and the H{sup {minus}} beam pulse length is 0.97 ms at a 60 Hz repetition rate. The RF pulses must be about 0.1 ms longer than the beam pulses, due to the Q of the accelerating cavities, and the time required to establish control of the cavity fields. The modulators for the klystrons in this accelerator are discussed in this paper. The SNS is designed to be expandable, so the beam power can be doubled or even quadrupled in the future. One of the double-power options is to double the beam pulse length and duty factor. The authors are specifying the klystrons to operate in this twice-duty-factor mode, and the modulator also should be expandable to 2 ms pulses at 60 Hz. Due to the long pulse length and low RF frequency of 805 MHz, the klystron power is specified at 2.5 MW peak, and the RF system will have 56 klystrons at 805 MHz, and three 1.25 MW peak power klystrons at 402.5 MHz for the low energy portion of the accelerator. The low frequency modulators are conventional floating-deck modulation anode control systems.

  12. Rf beam control for the AGS Booster

    SciTech Connect

    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.

  13. The design for the LCLS RF photoinjector

    NASA Astrophysics Data System (ADS)

    Alley, R.; Bharadwaj, V.; Clendenin, J.; Emma, P.; Fisher, A.; Frisch, J.; Kotseroglou, T.; Miller, R. H.; Palmer, D. T.; Schmerge, J.; Sheppard, J. C.; Woodley, M.; Yeremian, A. D.; Rosenzweig, J.; Meyerhofer, D. D.; Serafini, L.

    1999-06-01

    We report on the design of the RF photoinjector of the Linac Coherent Light Source. The RF photoinjector is required to produce a single 150 MeV bunch of ˜1 nC and ˜100 A peak current at a repetition rate of 120 Hz with a normalized rms transverse emittance of ˜1 π mm-mrad. The design employs a 1.6-cell S-band RF gun with an optical spot size at the cathode of a radius of ˜1 mm and a pulse duration with an rms sigma of ˜3 ps. The peak RF field at the cathode is 150 MV/m with extraction 57° ahead of the RF peak. A solenoidal field near the cathode allows the compensation of the initial emittance growth by the end of the injection linac. Spatial and temporal shaping of the laser pulse striking the cathode will reduce the compensated emittance even further. Also, to minimize the contribution of the thermal emittance from the cathode surface, while at the same time optimizing the quantum efficiency, the laser wavelength for a Cu cathode should be tunable around 260 nm. Following the injection linac the geometric emittance simply damps linearly with energy growth. PARMELA simulations show that this design will produce the desired normalized emittance, which is about a factor of two lower than has been achieved to date in other systems. In addition to low emittance, we also aim for laser amplitude stability of 1% in the UV and a timing jitter in the electron beam of 0.5 ps rms, which will lead to less than 10% beam intensity fluctuation after the electron bunch is compressed in the main linac.

  14. Rheumatoid factor (RF) distribution in periodontal disease.

    PubMed

    Thé, J; Ebersole, J L

    1991-05-01

    This study investigated the occurrence of an autoantibody, IgM rheumatoid factor, that may result from the chronic inflammation noted in periodontal disease and rheumatoid arthritis. In order to detect IgM-RF, a biotin-avidin ELISA was developed. This assay was found to be sensitive and accurate by testing a rheumatoid arthritis population. The characteristics of this rheumatoid arthritis group were further determined, such that the total serum immunoglobulin concentrations were slightly elevated although within the normal range for IgM, IgG, and IgA; IgG antibody levels were elevated against oral microorganisms of the genus Capnocytophaga, while elevated IgM antibody levels were noted to Bacteroides species. In a population of 260 subjects of which 171 were periodontal disease patients, 16 of 171 (9.4%) were seropositive for IgM-RF, of which the predominant disease types were advanced destructive periodontitis and adult periodontitis. For comparison, a random population of seronegative periodontal disease patients was constructed that was matched for sex and approximate age to the seropositive group. The total immunoglobulin levels of the two groups were not significantly different and the means of both were slightly lower than the rheumatoid arthritis group. When the antibody profiles of the two periodontal disease populations were compared it became evident that the RF-positive group showed IgM and IgG antibody that was significantly elevated to Capnocytophaga species and F. nucleatum. Therefore, the chronic inflammation associated with periodontitis appears to increase significantly the formation of IgM-RF; however, there does appear to be a relationship between IgM-RF and elevated antibody to selected oral microorganisms. PMID:1890163

  15. Dielectric properties and heating rate of broccoli powder as related to radio-frequency heating

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recently, Salmonella contamination was identified in low-moisture foods including dried vegetable powder. Radio Frequency (RF) dielectric heating is a potential alternative pasteurization method with short heating time. Dielectric properties of broccoli powder with 6.9, 9.1, 12.2, and 14.9%, w. b....

  16. Battery-Powered RF Pre-Ionization System for the Caltech Magnetohydrodynamically-Driven Jet Experiment: RF Discharge Properties and MHD-Driven Jet Dynamics

    NASA Astrophysics Data System (ADS)

    Chaplin, Vernon H.

    This thesis describes investigations of two classes of laboratory plasmas with rather different properties: partially ionized low pressure radiofrequency (RF) discharges, and fully ionized high density magnetohydrodynamically (MHD)-driven jets. An RF pre-ionization system was developed to enable neutral gas breakdown at lower pressures and create hotter, faster jets in the Caltech MHD-Driven Jet Experiment. The RF plasma source used a custom pulsed 3 kW 13.56 MHz RF power amplifier that was powered by AA batteries, allowing it to safely float at 4-6 kV with the cathode of the jet experiment. The argon RF discharge equilibrium and transport properties were analyzed, and novel jet dynamics were observed. Although the RF plasma source was conceived as a wave-heated helicon source, scaling measurements and numerical modeling showed that inductive coupling was the dominant energy input mechanism. A one-dimensional time-dependent fluid model was developed to quantitatively explain the expansion of the pre-ionized plasma into the jet experiment chamber. The plasma transitioned from an ionizing phase with depressed neutral emission to a recombining phase with enhanced emission during the course of the experiment, causing fast camera images to be a poor indicator of the density distribution. Under certain conditions, the total visible and infrared brightness and the downstream ion density both increased after the RF power was turned off. The time-dependent emission patterns were used for an indirect measurement of the neutral gas pressure. The low-mass jets formed with the aid of the pre-ionization system were extremely narrow and collimated near the electrodes, with peak density exceeding that of jets created without pre-ionization. The initial neutral gas distribution prior to plasma breakdown was found to be critical in determining the ultimate jet structure. The visible radius of the dense central jet column was several times narrower than the axial current channel

  17. Modeling of DC potential structures induced by RF sheaths with transverse currents in front of ICRF antenna

    SciTech Connect

    Faudot, E.; Heuraux, S.; Colas, L.

    2007-09-28

    RF heating is fully dependent on edge plasma conditions and particularly on convection of accelerated particles which can damage ICRH antennas (hot spots and impurity injection). These accelerated particle fluxes born in DC potential structures are induced by sheaths which rectify RF potentials. The potential map in front of antenna is not uniform so that transverse (to magnetic field) RF currents occur and can significantly modify the final DC potential map and thus convective flux distribution. The behavior of rectified potentials is investigated here for f = F{sub ci} and f>F{sub ci}, which was not yet achieved in our last works [1]. Therefore, a 2D fluid modeling including RF sheaths physics (parallel current) coupled with transverse RF currents has been built. The full description of the currents exhibits a maximum for frequencies around Fci, which can be explained by the fact that RF oscillation is capacitive at low frequency and inductive at high frequency. Both effects are present at frequencies around F{sub ci} and the DC peak potential appears for f = F{sub ci}/2. This is due to the rectification of the sinusoidal signal, which doubles the effective RF frequency radiated by the antenna. The theoretical DC peak value is 0.5 time the RF amplitude of the applied potential instead of 1/{pi} without transverse currents. For typical potential structures in front of ICRH antennas (centimetric wide and 1000 Volts peak potential), a factor between 0.4 and 0.45 can be expected according to 2D fiuid code results.

  18. RF couplers for normal-conducting photoinjector of high-power CW FEL

    SciTech Connect

    Kurennoy, S.

    2004-01-01

    A high-current emittance-compensated RF photoinjector is a key enabling technology for a high-power CW FEL. A preliminary design of a normal-conducting, 2.5-cell pi-mode, 700-MHz CW RF photoinjector that will be built for demonstration purposes, is completed. This photoinjector will be capable of accelerating a 100-mA electron beam (3 nC per bunch at 35 MHz bunch repetition rate) to 2.7 MeV while providing an emittance below 7 mm-mrad at the wiggler. More than 1 MW of RF power will be fed into the photoinjector cavity through two ridge-loaded tapered waveguides. The waveguides are coupled to the cavity by 'dog-bone' irises cut in a thick wall. Due to CW operation of the photoinjector, the cooling of the coupler irises is a rather challenging thermal management project. This paper presents results of a detailed electromagnetic modeling of the coupler-cavity system, which has been performed to select the coupler design that minimizes the iris heating due to RF power loss in its walls.

  19. RF Couplers for Normal-Conducting Photoinjector of High-Power CW FEL

    NASA Astrophysics Data System (ADS)

    Kurennoy, Sergey; Schrage, Dale; Wood, Richard; Schultheiss, Tom; Rathke, John; Young, Lloyd

    2004-05-01

    A high-current emittance-compensated RF photoinjector is a key enabling technology for a high-power CW FEL. A preliminary design of a normal-conducting, 2.5-cell pi-mode, 700-MHz CW RF photoinjector that will be build for demonstration purposes, is completed. This photoinjector will be capable of accelerating a 100-mA electron beam (3 nC per bunch at 35 MHz bunch repetition rate) to 2.7 MeV while providing an emittance below 7 mm-mrad at the wiggler. More than 1 MW of RF power will be fed into the photoinjector cavity through two ridge-loaded tapered waveguides. The waveguides are coupled to the cavity by "dog-bone" irises cut in a thick wall. Due to CW operation of the photoinjector, the cooling of the coupler irises is a rather challenging thermal management project. This paper presents results of a detailed electromagnetic modeling of the coupler-cavity system, which has been performed to select the coupler design that minimizes the iris heating due to RF power loss in its walls.

  20. Radio frequency heating of foods: principles, applications and related properties--a review.

    PubMed

    Piyasena, Punidadas; Dussault, Chantal; Koutchma, Tatiana; Ramaswamy, H S; Awuah, G B

    2003-01-01

    Radio frequency (RF) heating is a promising technology for food applications because of the associated rapid and uniform heat distribution, large penetration depth and lower energy consumption. Radio frequency heating has been successfully applied for drying, baking and thawing of frozen meat and in meat processing. However, its use in continuous pasteurization and sterilization of foods is rather limited. During RF heating, heat is generated within the product due to molecular friction resulting from oscillating molecules and ions caused by the applied alternating electric field. RF heating is influenced principally by the dielectric properties of the product when other conditions are kept constant. This review deals with the current status of RF heating applications in food processing, as well as product and system specific factors that influence the RF heating. It is evident that frequency level, temperature and properties of food, such as viscosity, water content and chemical composition affect the dielectric properties and thus the RF heating of foods. Therefore, these parameters should be taken into account when designing a radio frequency heating system for foods.

  1. Radio frequency heating of foods: principles, applications and related properties--a review.

    PubMed

    Piyasena, Punidadas; Dussault, Chantal; Koutchma, Tatiana; Ramaswamy, H S; Awuah, G B

    2003-01-01

    Radio frequency (RF) heating is a promising technology for food applications because of the associated rapid and uniform heat distribution, large penetration depth and lower energy consumption. Radio frequency heating has been successfully applied for drying, baking and thawing of frozen meat and in meat processing. However, its use in continuous pasteurization and sterilization of foods is rather limited. During RF heating, heat is generated within the product due to molecular friction resulting from oscillating molecules and ions caused by the applied alternating electric field. RF heating is influenced principally by the dielectric properties of the product when other conditions are kept constant. This review deals with the current status of RF heating applications in food processing, as well as product and system specific factors that influence the RF heating. It is evident that frequency level, temperature and properties of food, such as viscosity, water content and chemical composition affect the dielectric properties and thus the RF heating of foods. Therefore, these parameters should be taken into account when designing a radio frequency heating system for foods. PMID:14669879

  2. RUGGED CERAMIC WINDOW FOR RF APPLICATIONS

    SciTech Connect

    MIKE NEUBAUER

    2012-11-01

    High-current RF cavities that are needed for many accelerator applications are often limited by the power transmission capability of the pressure barriers (windows) that separate the cavity from the power source. Most efforts to improve RF window design have focused on alumina ceramic, the most popular historical choice, and have not taken advantage of new materials. Alternative window materials have been investigated using a novel Merit Factor comparison and likely candidates have been tested for the material properties which will enable construction in the self-matched window configuration. Window assemblies have also been modeled and fabricated using compressed window techniques which have proven to increase the power handling capability of waveguide windows. Candidate materials have been chosen to be used in fabricating a window for high power testing at Thomas Jefferson National Accelerator Facility.

  3. High power rf klystrons for linear accelerators

    SciTech Connect

    Konrad, G.T.

    1984-04-01

    Recent klystron developments at SLAC are described. The standard 40 MW klyston, which typically operates at 35 MW on the SLAC linac, is the starting point for the push to higher peak and average power. The standard tube is capable of a 2.5 ..mu..s rf pulse width at 360 pps. For the SLC a 50 MW klystron capable of 5 ..mu..s pulse width at 180 pps is under development. Another tube currently being worked on is a 150 MW klystron capable of 1 ..mu..s rf and 180 pps. Design criteria and actual operating experience for both developmental tubes are described. 10 references, 11 figures, 3 tables.

  4. An Efficient RF Source for Jlab

    SciTech Connect

    Neubauer, M.; Dudas, A.; Rimmer, Robert A.; Wang, Haipeng

    2013-12-01

    We propose the development of a highly reliable high efficiency RF source for JLAB with a lower lifetime cost operating at 80% efficiency with system operating costs of about 0.7M$/year for the 6 GeV machine. The design of the RF source will be based upon two injection locked magnetrons in a novel combining architecture for amplitude modulation and a cross field amplifier (CFA) as an output tube for the 12 GeV upgrade. A cost analysis including efficiency and reliability will be performed to determine the optimum system architecture. Several different system architectures will be designed and evaluated for a dual injection locked magnetron source using novel combining techniques and possibly a CFA as the output tube. A paper design for the 1497 MHz magnetron system will be completed. The optimum system architecture with all relevant specifications will be completed so that a prototype can be built.

  5. Rugged Ceramic Window for RF Applications

    SciTech Connect

    Neubauer, Michael; Johnson, Rolland P.; Rimmer, Robert; Elliot, Tom; Stirbet, Mircea

    2009-05-04

    High-current RF cavities that are needed for many accelerator applications are often limited by the power transmission capability of the pressure barriers (windows) that separate the cavity from the power source. Most efforts to improve RF window design have focused on alumina ceramic, the most popular historical choice, and have not taken advantage of new materials. Alternative window materials have been investigated using a novel Merit Factor comparison and likely candidates have been tested for the material properties which will enable construction in the self-matched window configuration. Window assemblies have also been modeled and fabricated using compressed window techniques which have proven to increase the power handling capability of waveguide windows. Candidate materials have been chosen to be used in fabricating a window for high power testing at Thomas Jefferson National Accelerator Facility.

  6. Experimental investigations of creep in gold RF-MEMS microstructures

    NASA Astrophysics Data System (ADS)

    Somà, Aurelio; De Pasquale, Giorgio; Saleem, Muhammad Mubasher

    2015-05-01

    Lifetime prediction and reliability evaluation of micro-electro-mechanical systems (MEMS) are influenced by permanent deformations caused by plastic strain induced by creep. Creep in microstructures becomes critical in those applications where permanent loads persist for long times and thermal heating induces temperature increasing respect to the ambient. Main goal of this paper is to investigate the creep mechanism in RF-MEMS microstructures by means of experiments. This is done firstly through the detection of permanent deformation of specimens and, then, by measuring the variation of electro-mechanical parameters (resonance frequency, pull-in voltage) that provide indirect evaluation of mechanical stiffness alteration from creep. To prevent the errors caused be cumulative heating of samples and dimensional tolerances, three specimens with the same nominal geometry have been tested per each combination of actuation voltage and temperature. Results demonstrated the presence of plastic deformation due to creep, combined with a component of reversible strain linked to the viscoelastic behavior of the material.

  7. Spallation neutron source/proposed rf system

    SciTech Connect

    Meth, M.; Brennan, J.M.

    1993-09-30

    The rf system for the synchrotrons of the spallation neutron source is designed to accelerate 1.4 {times} 10{sup 14} protons/pulse to an energy of 3.6 GeV. Injection energy is 600 MeV. The synchrotron repetition frequency is 30 Hz, with a 50% duty factor. The choice of operating frequency is somewhat arbitrary. The authors propose a low frequency of 1.3 to 1.6 MHz, which is the second harmonic of the revolution frequency. The advantages of such a low frequency system are: (1) There will be two bunches in the machines and the time between bunches will be sufficiently long to allow for the rise time of the extraction kicker. No missing bunches will be necessary, which simplifies injection, and transient beam loading problems are avoided. (2) With only two bunches there are no unstable coupled-bunch modes of longitudinal instability. (3) In multi-gap low frequency cavities the transient time factor is essentially unity because the rf wavelength is much longer than the cavity dimensions. (4) Cavities in this low frequency range are basically lumped-element type structures, where the sources of the inductance and capacitance are clearly identified. This allows effective control of higher order mode impedances in such cavities. (5) Ferrite-loaded low-frequency cavities are necessarily low impedance structures; ferrites are lossy. This low impedance makes it possible to achieve system stability without large amounts of feedback in a heavily beam loaded system. (6) BNL has a good deal of experience in building rf systems in this range of frequency, voltage, and power level. This report outlines the essential parameters of a practical rf system for the synchrotrons of the Spallation Neutron Source. The design uses materials, ferrites and vacuum tubes, that are commercially available and with which the laboratory has recent experience.

  8. Wireless RF communication in biomedical applications

    NASA Astrophysics Data System (ADS)

    Jones, Inke; Ricciardi, Lucas; Hall, Leonard; Hansen, Hedley; Varadan, Vijay; Bertram, Chris; Maddocks, Simon; Enderling, Stefan; Saint, David; Al-Sarawi, Said; Abbott, Derek

    2008-02-01

    This paper focuses on wireless transcutaneous RF communication in biomedical applications. It discusses current technology, restrictions and applications and also illustrates possible future developments. It focuses on the application in biotelemetry where the system consists of a transmitter and a receiver with a transmission link in between. The transmitted information can either be a biopotential or a nonelectric value like arterial pressure, respiration, body temperature or pH value. In this paper the use of radio-frequency (RF) communication and identification for those applications is described. Basically, radio-frequency identification or RFID is a technology that is analogous to the working principle of magnetic barcode systems. Unlike magnetic barcodes, passive RFID can be used in extreme climatic conditions—also the tags do not need to be within close proximity of the reader. Our proposed solution is to exploit an exciting new development in making circuits on polymers without the need for battery power. This solution exploits the principle of a surface acoustic wave (SAW) device on a polymer substrate. The SAW device is a set of interdigitated conducting fingers on the polymer substrate. If an appropriate RF signal is sent to the device, the fingers act as microantennas that pick up the signal, and this energy is then converted into acoustic waves that travel across the surface of the polymer substrate. Being a flexible polymer, the acoustic waves cause stresses that can either contract or stretch the material. In our case we mainly focus on an RF controllable microvalve that could ultimately be used for fertility control.

  9. RF subsystem design for microwave communication receivers

    NASA Astrophysics Data System (ADS)

    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.

  10. Microsystem packaging of an RF SAW correlator.

    SciTech Connect

    Palmer, David A.; Brocato, Robert Wesley; Studor, George F.

    2005-01-01

    An electrically programmable surface acoustic wave (SAW) correlator was recently completed from design through small scale production in support of low power space-based communications for NASA. Three different versions of this RF microsystem were built to satisfy design requirements and overcome packaging and system reliability related issues. Flip-chip packaging and conventional thick film hybrid assembly techniques are compared in the fabrication of this microsystem.

  11. Superconducting RF systems for eRHIC

    SciTech Connect

    Belomestnykh S.; Ben-Zvi, I.; Brutus, J.C.; Hahn, H. et al

    2012-05-20

    The proposed electron-hadron collider eRHIC will consist of a six-pass 30-GeV electron Energy Recovery Linac (ERL) and one of RHIC storage rings operating with energy up to 250 GeV. The collider design extensively utilizes superconducting RF (SRF) technology in both electron and hadron parts. This paper describes various SRF systems, their requirements and parameters.

  12. Cathode Ion Bombardment in RF Photoguns

    SciTech Connect

    Pozdeyev,E.; Kayran, D.; Litvinenko, V.

    2008-09-01

    In this paper, we use the method of rapid oscillating field to solve the equation of ion motion in an RF gun. We apply the method to the BNL 1/2-cell SRF photogun and demonstrate that a significant portion of ions produced in the gun can reach the cathode if no special precautions are taken. Also, the paper proposes a simple mitigation recipe that can reduce the rate of ion bombardment.

  13. Momentum errors in an RF separated beam

    SciTech Connect

    T. Kobilarcik

    2002-09-19

    The purity of an RF separated beam is affected by the difference in mass of the particle types and the momentum bite of the beam. The resulting time-of-flight difference between different types allows separation to occur; the finite momentum bite results in chromatic aberration. Both these features also give rise to a particle type dependent velocity bite, which must also be taken into account. This memo demonstrates a generalizable method for calculating the effect.

  14. NSLS-II RF Cryogenic System

    SciTech Connect

    Rose, J.; Dilgen, T.; Gash, B.; Gosman, J.; Mortazavi, P.; Papu, J.; Ravindranath, V.; Sikora, R.; Sitnikov, A.; Wilhelm, H.; Jia, Y.; Monroe, C.

    2015-05-03

    The National Synchrotron Light Source II is a 3 GeV X-ray user facility commissioned in 2014. A new helium refrigerator system has been installed and commissioned to support the superconducting RF cavities in the storage ring. Special care was taken to provide very stable helium and LN2 pressures and flow rates to minimize microphonics and thermal effects at the cavities. Details of the system design along with commissioning and early operations data will be presented.

  15. Biologic response to microwave/RF energy

    SciTech Connect

    Michaelson, S.M.

    1980-01-01

    A systematic and up-to-date review of observations and theoretical approaches to the biological effects and health implications of exposure to microwave/radiofrequency energies is presented. A primary objective is to review and place available information and concepts in proper perspective to understand and encourage the full potential for the beneficial uses of these energies while at the same time preventing adverse effects to individuals exposed to microwaves/RF.

  16. New Developments on PBG RF Cavities

    NASA Astrophysics Data System (ADS)

    Smirnov, A. V.; Yu, D.

    2004-12-01

    Performance and design features of metal PBG and rod-loaded cavities for single-beam and multi-beam acceleration and rf power generation devices are considered. Fundamental differences of the performance between single-defect and multi-defect structures are identified. Rod-loaded cavity designs are considered for a 6-beam klystron. Preliminary design of the X-band MBK demonstrates feasibility of generating high power with high efficiency in a very compact construction.

  17. Silicon on Insulator MESFETs for RF Amplifiers.

    PubMed

    Wilk, Seth J; Balijepalli, Asha; Ervin, Joseph; Lepkowski, William; Thornton, Trevor J

    2010-03-01

    CMOS compatible, high voltage SOI MESFETs have been fabricated using a standard 3.3V CMOS process without any changes to the process flow. A 0.6μm gate length device operates with a cut-off frequency of 7.3GHz and a maximum oscillation frequency of 21GHz. There is no degradation in device performance up to its breakdown voltage, which greatly exceeds that of CMOS devices on the same process. Other figures of merit of relevance to RF front-end design are presented, including the maximum stable gain and noise figure. An accurate representation of the device in SPICE has been developed using the commercially available TOM3 model. Using the SOI MESFET model, a source degenerated low noise RF amplifier targeting operation near 1GHz has been designed. The amplifier was fabricated on a PCB board and operates at 940MHz with a minimum NF of 3.8dB and RF gain of 9.9dB while only consuming 5mW of DC power. PMID:20657816

  18. Inductively coupled wireless RF coil arrays.

    PubMed

    Bulumulla, S B; Fiveland, E; Park, K J; Foo, T K; Hardy, C J

    2015-04-01

    As the number of coils increases in multi-channel MRI receiver-coil arrays, RF cables and connectors become increasingly bulky and heavy, degrading patient comfort and slowing workflow. Inductive coupling of signals provides an attractive "wireless" approach, with the potential to reduce coil weight and cost while simplifying patient setup. In this work, multi-channel inductively coupled anterior arrays were developed and characterized for 1.5T imaging. These comprised MR receiver coils inductively (or "wirelessly") linked to secondary or "sniffer" coils whose outputs were transmitted via preamps to the MR system cabinet. The induced currents in the imaging coils were blocked by passive diode circuits during RF transmit. The imaging arrays were totally passive, obviating the need to deliver power to the coils, and providing lightweight, untethered signal reception with easily positioned coils. Single-shot fast spin echo images were acquired from 5 volunteers using a 7-element inductively coupled coil array and a conventionally cabled 7-element coil array of identical geometry, with the inductively-coupled array showing a relative signal-to-noise ratio of 0.86 +/- 0.07. The concept was extended to a larger 9-element coil array to demonstrate the effect of coil element size on signal transfer and RF-transmit blocking. PMID:25523607

  19. Silicon Micromachining in RF and Photonic Applications

    NASA Technical Reports Server (NTRS)

    Lin, Tsen-Hwang; Congdon, Phil; Magel, Gregory; Pang, Lily; Goldsmith, Chuck; Randall, John; Ho, Nguyen

    1995-01-01

    Texas Instruments (TI) has developed membrane and micromirror devices since the late 1970s. An eggcrate space membrane was used as the spatial light modulator in the early years. Discrete micromirrors supported by cantilever beams created a new era for micromirror devices. Torsional micromirror and flexure-beam micromirror devices were promising for mass production because of their stable supports. TI's digital torsional micromirror device is an amplitude modulator (known as the digital micromirror device (DMD) and is in production development, discussed elsewhere. We also use a torsional device for a 4 x 4 fiber-optic crossbar switch in a 2 cm x 2 cm package. The flexure-beam micromirror device is an analog phase modulator and is considered more efficient than amplitude modulators for use in optical processing systems. TI also developed millimeter-sized membranes for integrated optical switches for telecommunication and network applications. Using a member in radio frequency (RF) switch applications is a rapidly growing area because of the micromechanical device performance in microsecond-switching characteristics. Our preliminary membrane RF switch test structure results indicate promising speed and RF switching performance. TI collaborated with MIT for modeling of metal-based micromachining.

  20. Negative ion kinetics in RF glow discharges

    SciTech Connect

    Gottscho, R.A.; Gacbe, C.E.

    1986-04-01

    Using temporally and spatially resolved laser spectroscopy, the authors have determined the identities, approximate concentrations, effects on the local field, and kinetics of formation and loss of negative ions in RF discharges. CI/sup -/ and BCI/sub 3//sup -/ are the dominant negative ions found in low-frequency discharges through CI/sub 2/ and BCI/sub 3/, respectively. The electron affinity for CI is measured to be 3.6118 +- 0.0005 eV. Negative ion kinetics are strongly affected by application of the RF field. Formation of negative ions by attachment of slow electrons in RF discharges is governed by the extent and duration of electron energy relaxation. Similarly, destruction of negative ions by collisional detachment and field extraction is dependent upon ion energy modulation. Thus, at low frequency, the anion density peaks at the beginning of the anodic and cathodic half-cycles after electrons have attached but before detachment and extraction have had time to occur. At higher frequencies, electrons have insufficient time to attach before they are reheated and the instantaneous anion density in the sheath is greatly reduced. When the negative ion density is comparable to the positive ion density, the plasma potential is observed to lie below the anode potential, double layers form between sheath and plasma, and anions and electrons are accelerated by large sheath fields to electrode surfaces.

  1. RF Gun Photocathode Research at SLAC

    SciTech Connect

    Jongewaard, E.; Akre, R.; Brachmann, A.; Corbett, J.; Gilevich, S.; Grouev, K.; Hering, P.; P.Krejcik,; Lewandowski, J.; Loos, H.; Montagne, T.; Sheppard, J.C.; Stefan, P.; Vlieks, A.; Weathersby, S.; Zhou, F.; /SLAC

    2012-05-16

    LCLS is presently operating with a third copper photocathode in the original rf gun, with a quantum efficiency (QE) of {approx}1 x 10{sup -4} and projected emittance {gamma}{var_epsilon}{sub x,y} = 0.45 {micro}m at 250 pC bunch charge. The spare LCLS gun is installed in the SLAC Accelerator Structure Test Area (ASTA), fully processed to high rf power. As part of a wider photocathode R and D program, a UV laser system and additional gun diagnostics are being installed at ASTA to measure QE, QE lifetime, and electron beam emittance under a variety of operating conditions. The near-term goals are to test and verify the spare photocathode production/installation sequence, including transfer from the final holding chamber to the rf gun. Mid- and longer-term goals include development of a rigorous understanding of plasma and laser-assisted surface conditioning and investigation of new, high-QE photocathode materials. In parallel, an x-ray photoemission spectroscopy station is nearing completion, to analyze Cu photocathode surface chemistry. In this paper we review the status and anticipated operating parameters of ASTA and the spectroscopy test chamber.

  2. Silicon on Insulator MESFETs for RF Amplifiers

    PubMed Central

    Balijepalli, Asha; Ervin, Joseph; Lepkowski, William; Thornton, Trevor J.

    2010-01-01

    CMOS compatible, high voltage SOI MESFETs have been fabricated using a standard 3.3V CMOS process without any changes to the process flow. A 0.6μm gate length device operates with a cut-off frequency of 7.3GHz and a maximum oscillation frequency of 21GHz. There is no degradation in device performance up to its breakdown voltage, which greatly exceeds that of CMOS devices on the same process. Other figures of merit of relevance to RF front-end design are presented, including the maximum stable gain and noise figure. An accurate representation of the device in SPICE has been developed using the commercially available TOM3 model. Using the SOI MESFET model, a source degenerated low noise RF amplifier targeting operation near 1GHz has been designed. The amplifier was fabricated on a PCB board and operates at 940MHz with a minimum NF of 3.8dB and RF gain of 9.9dB while only consuming 5mW of DC power. PMID:20657816

  3. RF Photonic Technology in Optical Fiber Links

    NASA Astrophysics Data System (ADS)

    Chang, William S. C.

    2007-06-01

    List of contributors; Introduction and preface; 1. Figures of merit and performance analysis of photonic microwave links Charles Cox and William S. C. Chang; 2. RF subcarrier links in local access networks Xiaolin Lu; 3. Analog modulation of semiconductor lasers Joachim Piprek and John E. Bowers; 4. LiNbO3 external modulators and their use in high performance analog links Gary E. Betts; 5. Broadband traveling wave modulators in LiNbO3 Marta M. Howerton and William K. Burns; 6. Multiple quantum well electroabsorption modulators for RF photonic links William S. C. Chang; 7. Polymer modulators for RF photonics Timothy Van Eck; 8. Photodiodes for high performance analog links P. K. L. Yu and Ming C. Wu; 9. Opto-electronic oscillators X. Steve Yao; 10. Photonic link techniques for microwave frequency conversion Stephen A. Pappert, Roger Helkey and Ronald T. Logan Jr; 11. Antenna-coupled millimeter-wave electro-optical modulators William B. Bridges; 12. System design and performance of wideband photonic phased array antennas Greg L. Tangonan, Willie Ng, Daniel Yap and Ron Stephens; Acknowledgements; References; Index.

  4. GAM & RF for 3D mapping of multinomial peat properties.

    NASA Astrophysics Data System (ADS)

    Poggio, Laura; Gimona, Alessandro; Aalders, Inge; Morrice, Jane; Hough, Rupert

    2013-04-01

    Different statistical methods have been proposed for fitting the empirical quantitative function linking the soil information to the scorpan factors, while taking into account the spatial structure of the data . Regression kriging extends the methods of kriging and co-kriging and it has been further extended by the use of GAMs (Generalized Additive Models) with the estimation of uncertainty. When multinomial data are modelled, advanced non-parametric methods, such as CART (Classification and Regression Tree), can be used. CARTs have been used widely to estimate soil properties. Bagging trees and Random Forest (RF) approaches have among the best performances among CART methods. CARTs have been used in DSM applications, While RF have often been used in ecological modelling, fewer examples exist in DSM, such as soil erosion occurrence, soil types prediction and soil organic carbon content. In this paper we propose a methodology to map multinomial peat properties in 3D space with a combination of GAMs and RF. The methodology was applied to the humification (according to the VonPost classification) classes in a bog (18 km2) in the north-east of Scotland. A large survey campaign was carried out in 1955 and humification information were collected at 125 points. In order to integrate the information from the GAM in the RT, a series of binary GAMs were fitted using DEM-derived information as covariates. The binary GAMs were fitted assigning 1 if the class considered was present at the location, 0 if the class considered was absent. The probability predictions resulting from the binary GAMs, were included in the pool of covariates used for the RT together with other ancillary covariates. The model diagnostics had a fair to good agreement between measured and modelled values (K statistics). The probability predictions resulting from the binary GAMs proved to be important variables, increasing the agreement of the model. The obtained spatial distribution of values on the

  5. Reduction of RF sheaths potentials by compensation or suppression of parallel RF currents on ICRF antennae

    NASA Astrophysics Data System (ADS)

    Mendes, A.; Colas, L.; Vulliez, K.; Argouarch, A.; Milanesio, D.

    2009-11-01

    Radio Frequency (RF) sheaths are suspected to limit the performance of present-day Ion Cyclotron Range of Frequencies (ICRF) antennae over long pulses and should be minimized in future Fusion devices. Within the simplest models, RF sheath effects are quantified by the integral VRF = ∫E//ṡdl where the parallel RF field E// is linked with the slow wave. On "long open field lines" with large toroidal extension on both sides of the antenna it was shown that VRF is excited by parallel RF currents j// flowing on the antenna structure. We thus propose two ways to reduce |VRF| by acting on j// on the antenna front face. The first method, more adapted for protruding antennae, consists in avoiding the j// circulation on the antenna structure, by slotting the antenna frame on its horizontal edges and by cutting partially the Faraday screen rods. The second method, well suited for recessed antennae, consists in compensating j// of opposite signs along long flux tubes, with parallelepiped antennae aligned with tilted flux tubes. The different concepts are assessed numerically on a 2-strap Tore Supra antenna phased [0, π] using near RF fields from the antenna code TOPICA. Simulations stress the need to suppress all current paths for j// to reduce substantially |VRF| over the whole antenna height.

  6. SEMICONDUCTOR DEVICES: Large signal RF power transmission characterization of InGaP HBT for RF power amplifiers

    NASA Astrophysics Data System (ADS)

    Lixin, Zhao; Zhi, Jin; Xinyu, Liu

    2010-01-01

    The large signal RF power transmission characteristics of an advanced InGaP HBT in an RF power amplifier are investigated and analyzed experimentally. The realistic RF powers reflected by the transistor, transmitted from the transistor and reflected by the load are investigated at small signal and large signal levels. The RF power multiple frequency components at the input and output ports are investigated at small signal and large signal levels, including their effects on RF power gain compression and nonlinearity. The results show that the RF power reflections are different between the output and input ports. At the input port the reflected power is not always proportional to input power level; at large power levels the reflected power becomes more serious than that at small signal levels, and there is a knee point at large power levels. The results also show the effects of the power multiple frequency components on RF amplification.

  7. Nonlinear phenomena in RF wave propagation in magnetized plasma: A review

    NASA Astrophysics Data System (ADS)

    Porkolab, Miklos

    2015-12-01

    Nonlinear phenomena in RF wave propagation has been observed from the earliest days in basic laboratory experiments going back to the 1960s [1], followed by observations of parametric instability (PDI) phenomena in large scale RF heating experiments in magnetized fusion plasmas in the 1970s and beyond [2]. Although not discussed here, the importance of PDI phenomena has also been central to understanding anomalous absorption in laser-fusion experiments (ICF) [3]. In this review I shall discuss the fundamentals of nonlinear interactions among waves and particles, and in particular, their role in PDIs. This phenomenon is distinct from quasi-linear phenomena that are often invoked in calculating absorption of RF power in wave heating experiments in the core of magnetically confined plasmas [4]. Indeed, PDIs are most likely to occur in the edge of magnetized fusion plasmas where the electron temperature is modest and hence the oscillating quiver velocity of charged particles can be comparable to their thermal speeds. Specifically, I will review important aspects of PDI theory and give examples from past experiments in the ECH/EBW, lower hybrid (LHCD) and ICRF/IBW frequency regimes. Importantly, PDI is likely to play a fundamental role in determining the so-called "density limit" in lower hybrid experiments that has persisted over the decades and still central to understanding present day experiments [5-7].

  8. Computer simulation of RF liver ablation on an MRI scan data

    NASA Astrophysics Data System (ADS)

    Kosturski, N.; Margenov, S.; Vutov, Y.

    2012-10-01

    Radio-frequency (RF) ablation is a low invasive technique for treatment of liver tumors. An RF-probe is inserted in the patient's liver and a ground pad is applied to the skin. Then the tumor is heated with RF current. The heat causes the destruction of tumor cells. We use the finite element method (FEM) to simulate and analyze various aspects of the procedure. A 3D image of the patient's liver is obtained from a magnetic resonance imaging (MRI) scan. Then, the geometry for the RFprobe and the ground pad is added. Our focus is on the influence of the position of the ground pads on the ablation process. Our simulation is based on an unstructured mesh. The size of the mesh is large due to the complexity of the domain. We discretize and solve the problem on a parallel computer using MPI for the parallelization. The presented numerical tests are performed on IBM Blue Gene/P machine at BGSC. The parallel efficiency of the incorporated Boomer AMG solver is demonstrated as well.

  9. Nonlinear phenomena in RF wave propagation in magnetized plasma: A review

    SciTech Connect

    Porkolab, Miklos

    2015-12-10

    Nonlinear phenomena in RF wave propagation has been observed from the earliest days in basic laboratory experiments going back to the 1960s [1], followed by observations of parametric instability (PDI) phenomena in large scale RF heating experiments in magnetized fusion plasmas in the 1970s and beyond [2]. Although not discussed here, the importance of PDI phenomena has also been central to understanding anomalous absorption in laser-fusion experiments (ICF) [3]. In this review I shall discuss the fundamentals of nonlinear interactions among waves and particles, and in particular, their role in PDIs. This phenomenon is distinct from quasi-linear phenomena that are often invoked in calculating absorption of RF power in wave heating experiments in the core of magnetically confined plasmas [4]. Indeed, PDIs are most likely to occur in the edge of magnetized fusion plasmas where the electron temperature is modest and hence the oscillating quiver velocity of charged particles can be comparable to their thermal speeds. Specifically, I will review important aspects of PDI theory and give examples from past experiments in the ECH/EBW, lower hybrid (LHCD) and ICRF/IBW frequency regimes. Importantly, PDI is likely to play a fundamental role in determining the so-called “density limit” in lower hybrid experiments that has persisted over the decades and still central to understanding present day experiments [5-7].

  10. High temperature UF6 RF plasma experiments applicable to uranium plasma core reactors

    NASA Technical Reports Server (NTRS)

    Roman, W. C.

    1979-01-01

    An investigation was conducted using a 1.2 MW RF induction heater facility to aid in developing the technology necessary for designing a self critical fissioning uranium plasma core reactor. Pure, high temperature uranium hexafluoride (UF6) was injected into an argon fluid mechanically confined, steady state, RF heated plasma while employing different exhaust systems and diagnostic techniques to simulate and investigate some potential characteristics of uranium plasma core nuclear reactors. The development of techniques and equipment for fluid mechanical confinement of RF heated uranium plasmas with a high density of uranium vapor within the plasma, while simultaneously minimizing deposition of uranium and uranium compounds on the test chamber peripheral wall, endwall surfaces, and primary exhaust ducts, is discussed. The material tests and handling techniques suitable for use with high temperature, high pressure, gaseous UF6 are described and the development of complementary diagnostic instrumentation and measurement techniques to characterize the uranium plasma, effluent exhaust gases, and residue deposited on the test chamber and exhaust system components is reported.

  11. Technology development of RF MEMS switches on printed circuit boards

    NASA Astrophysics Data System (ADS)

    Chang, Hung-Pin

    Today, some engineers have shifted their focus on the micro-electro-mechanical system (MEMS) to pursue better technological advancements. Recent development in RF MEMS technologies have lead to superior switch characteristics, i.e., very low insertion loss, very low power requirements, and high isolation comparing to the conventional semiconductor devices. This success has promised the potential of MEMS to revolutionize RF and microwave system implementation for the next generation of communication applications. However, RF MEMS switches integrated monolithically with various RF functional components on the same substrate to create multifunctional and reconfigurable complete communication systems remains to be a challenge research topic due to the concerns of the high cost of packaging process and the high cost of RF matching requirements in module board implementation. Furthermore, the fabrication of most RF MEMS switches requires thickness control and surface planarization of wide metal lines prior to deposition of a metal membrane bridge, which poses a major challenge to manufacturability. To ease the fabrication of RF MEMS switches and to facilitate their integration with other RF components such as antennas, phase delay lines, tunable filters, it is imperative to develop a manufacturable RF MEMS switch technology on a common substrate housing all essential RF components. Development of a novel RF MEMS technology to build a RF MEMS switch and provide a system-level packaging on microwave laminated printed circuit boards (PCBs) are proposed in this dissertation. Two key processes, high-density inductively coupled plasma chemical vapor deposition (HDICP CVD) for low temperature dielectric deposition, and compressive molding planarization (COMP) for the temporary sacrificial polymer planarization have been developed for fabricating RF MEMS switches on PCBs. Several membrane-type capacitive switches have been fabricated showing excellent RF performance and dynamic

  12. Similarities Between RF- and Lightning-Induced Airglow in the Upper Atmosphere

    NASA Astrophysics Data System (ADS)

    Sentman, D. D.; Wescott, E. M.; Stenbaek-Nielsen, H. C.; Moudry, D. R.; Sao Sabbas, F. T.

    2002-12-01

    Recent experiments in Alaska using the HAARP and HIPAS high power RF transmitters have succeeded in artificially generating oxygen neutral and molecular nitrogen ion emissions, or artificial airglow, in the ionosphere. An apparently different type of transient airglow generated by lightning, in the form of sprites and elves in the mesosphere and lower ionosphere, has been extensively studied in recent years. Despite occurring in vastly different atmospheric regimes, these seemingly disparate forms of optical emissions, one derived from artificial modification of the ionosphere and the other from natural thunderstorm processes, share a common underlying microphysical description based on electron heating by RF and quasi-DC electric fields, respectively, accompanied by impact excitation of ambient neutrals and subsequent optical relaxation and quenching of excited species. The theoretical description of these processes has its roots in work described by Zel'dovich and Raizer on the microphysics of shock waves and high temperature gasses. This work was subsequently adapted by Gurevich, Papadopoulis and coworkers to describe high power microwave interactions with the stratosphere. Extended to include nonlinear plasma interactions, it is the basis for understanding the effects of intense RF waves on the ionosphere, including creation of airglow, from high power transmitters currently operating in Alaska, Sweden and Russia. Pasko and coworkers have successfully adapted these theories to conditions appropriate to lightning impulse interactions with the upper atmosphere to describe the basic breakdown and streamer processes associated with sprite production. Thus, sprites and RF-induced airglow theories share a common set of concepts at the microphysical level and a common theoretical language. This talk outlines areas of especially strong overlap, and describes some possible high power RF ionospheric interaction experiments that could be performed to help study

  13. A 201 MHz RF cavity design with non-stressed pre-curved Be windows for muon cooling channels

    SciTech Connect

    Li, Derun; Ladran, A.; Staples, J.; Virostek, S.; Zisman, M.; Lau, W.; Yang, S .; Rimmer, R.A.

    2003-05-01

    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 precurved 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.

  14. Heat pipe array heat exchanger

    DOEpatents

    Reimann, Robert C.

    1987-08-25

    A heat pipe arrangement for exchanging heat between two different temperature fluids. The heat pipe arrangement is in a ounterflow relationship to increase the efficiency of the coupling of the heat from a heat source to a heat sink.

  15. Improvement of beam macropulse properties using slim thermionic cathode in IAE RF gun

    NASA Astrophysics Data System (ADS)

    Kii, Toshiteru; Miyasako, Atsushi; Hayashi, Syusuke; Masuda, Kai; Ohgaki, Hideaki; Yoshikawa, Kiyoshi; Yamazaki, Tetsuo

    2004-08-01

    A long beam macropulse is strongly required for free-electron lasers. RF guns can potentially produce high brightness electron beam using a simple and compact system. However, due to a back-bombardment, a cathode surface is overheated. Thus, it is difficult to maintain a constant beam current and beam energy during a macropulse. The use of a photo cathode with a short-pulsed laser is one of the solutions, but it affects the simplicity and the compactness of the RF guns. We studied a mechanism of back-bombardment and experimentally and numerically found that a low energy component of the back-streaming electrons plays an important role in cathode surface heating.

  16. Tumor Selective Hyperthermia Induced by Short-Wave Capacitively-Coupled RF Electric-Fields

    PubMed Central

    Raoof, Mustafa; Cisneros, Brandon T.; Corr, Stuart J.; Palalon, Flavio; Curley, Steven A.; Koshkina, Nadezhda V.

    2013-01-01

    There is a renewed interest in developing high-intensity short wave capacitively-coupled radiofrequency (RF) electric-fields for nanoparticle-mediated tumor-targeted hyperthermia. However, the direct thermal effects of such high-intensity electric-fields (13.56 MHZ, 600 W) on normal and tumor tissues are not completely understood. In this study, we investigate the heating behavior and dielectric properties of normal mouse tissues and orthotopically-implanted human hepatocellular and pancreatic carcinoma xenografts. We note tumor-selective hyperthermia (relative to normal mouse tissues) in implanted xenografts that can be explained on the basis of differential dielectric properties. Furthermore, we demonstrate that repeated RF exposure of tumor-bearing mice can result in significant anti-tumor effects compared to control groups without detectable harm to normal mouse tissues. PMID:23861912

  17. THE PENETRABILITY OF A THIN METALLIC FILM INSIDE THE RF FIELD.

    SciTech Connect

    ZHAO, Y.; BEN-ZVI, I.; CHANG, X.; RAO, T.; CHEN, W.; DINARDO, R.; BEUTENMULLER, R.

    2005-05-16

    Thin metallic film was widely applied in various areas. Especially, recently we are planning to apply it in a ''Secondary emission enhanced photo-injector'', in which a diamond cathode is coated with a metallic film on its back to serve as a current path. The thickness of the film is originally considered to be in the order of 10 nm, which is much less than the skin depth, by a factor of almost 200. One would think intuitively that the RF filed would penetrate such a thin film. However, we found it is not true. The film will block most of the field. This paper addresses theoretical analysis as well as the experimental results, and demonstrates that the penetrability of a thin film is very poor. Consequently, most of the RF current will flow on the thin film causing a serious heating problem.

  18. Measurement of rf voltages on the plasma-touching surfaces of ICRF antennas

    SciTech Connect

    Hoffman, D.J.; Baity, F.W.; Bell, G.L.; Bigelow, T.S.; Caughman, J.B.O.; Goulding, R.H.; Haste, G.R.; Ryan, P.M.; Zhang, H.

    1995-09-01

    Measurements of the rf voltages on Faraday shields and protection bumpers have been made for several loop antennas, including the mock-up antenna and Al for JET, the original antenna for Tore Supra, the present ASDEX-U antenna, and the folded waveguide. The loop antennas show voltages that scale to {approx}12 kV for a maximum input voltage of 30 kV with 0/0 phasing. The voltages are dramatically reduced for 0/{pi} phasing. These voltages are significant in that they can substantially increase the rf sheath potential beyond the levels associated with the simple electromagnetic field linkage from the current straps that results in plasma heating. In this paper, we investigate and measure the source of these voltages, their scaling with antenna impedance, and the differences between the loop arrays.

  19. An analytical model for floating probes in AC plasma and its application to double probes for high density, high power RF discharges

    NASA Astrophysics Data System (ADS)

    Caneses, Juan Francisco; Blackwell, Boyd; Plasma Research Laboratory Team

    2013-10-01

    In this work we provide an analytical model that allows one to quantitatively assess the RF compensation performance and suitability of the double probe technique for use in RF generated plasma. The model is based in the theory of the self-bias effect as described in Braithwaite's work, which we extend to include the time resolved behavior of floating probes. We provide experimental verification for this model and show that the theory of transient RF self-bias probes and harmonic current detection probes are limiting cases of this extended model. Furthermore, the model shows that the RF compensation is solely dependent on the sheath impedance, the probe's stray capacitance to ground and RF frequency. In addition, we use these results to implement a double probe system for use in high density helicon plasma where heat loads could potentially damage the intricate components in an RF compensating circuit. Finally we use this model to (1) recommend ways to extend the operational regime of double probes where the plasma conditions would render them unsuitable and to (2) comment on the use of this model to aid design of RF compensated Langmuir probes.

  20. Overview of the 100 mA average-current RF photoinjector

    NASA Astrophysics Data System (ADS)

    Nguyen, D. C.; Colestock, P. L.; Kurennoy, S. S.; Rees, D. E.; Regan, A. H.; Russell, S.; Schrage, D. L.; Wood, R. L.; Young, L. M.; Schultheiss, T.; Christina, V.; Cole, M.; Rathke, J.; Shaw, J.; Eddy, C.; Holm, R.; Henry, R.; Yater, J.

    2004-08-01

    High-average-power FELs require high-current, low-emittance and low-energy-spread electron beams. These qualities have been achieved with RF photoinjectors operating at low-duty factors. To date, a high-average-current RF photoinjector operating continuously at 100% duty factor is yet to be demonstrated. The principal challenges of a high-duty-factor normal-conducting RF photoinjector are related to applying a high accelerating gradient continuously, thus generating large ohmic losses in the cavity walls, cooling the injector cavity walls and the high-power RF couplers, and finding a photocathode with reasonable Q.E. that can survive the poor vacuum of the RF photoinjector. We present the preliminary design of a normal-conducting 700 MHz photoinjector with solenoid magnetic fields for emittance compensation. The photoinjector is designed to produce 2.7 MeV electron beams at 3 nC bunch charge and 35 MHz repetition rate (100 mA average current). The photoinjector consists of a 2 {1}/{2}-cell, π-mode, RF cavity with on-axis electric coupling, and a non-resonant vacuum plenum. Heat removal in the resonant cells is achieved via dense arrays of internal cooling passages capable of handling high-velocity water flows. Megawatt RF power is coupled into the injector through two tapered ridge-loaded waveguides. PARMELA simulations show that the 2 {1}/{2}-cell injector can produce a 7 μm emittance directly. Transverse plasma oscillations necessitate additional acceleration and a second solenoid to realign the phase space envelopes of different axial slices at higher energy, resulting in a normalized rms emittance of 6.5 μm and 34 keV rms energy spread. We are developing a novel cesiated p-type GaN photocathode with 7% quantum efficiency at 350 nm and a cesium dispenser to replenish the cathode with cesium through a porous silicon carbide substrate. These performance parameters will be necessary for the design of the 100 kW FEL.

  1. Heat Loss Imagery

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Infrared scanning devices are being used to produce images that show, by color or black-and-white shading differences, which buildings and homes are losing heat to the outdoors, and how much. Heat loss surveys done by Texas Instruments, Daedalus Enterprises, Inc. and other companies have growing acceptance of their services among industrial firms, utilities, local governments, and state and federal agencies interested in promoting heat loss awareness and inspiring corrective actions.

  2. Thermal Deformation and RF Performance Analyses for the SWOT Large Deployable Ka-Band Reflectarray

    NASA Technical Reports Server (NTRS)

    Fang, H.; Sunada, E.; Chaubell, J.; Esteban-Fernandez, D.; Thomson, M.; Nicaise, F.

    2010-01-01

    A large deployable antenna technology for the NASA Surface Water and Ocean Topography (SWOT) Mission is currently being developed by JPL in response to NRC Earth Science Tier 2 Decadal Survey recommendations. This technology is required to enable the SWOT mission due to the fact that no currently available antenna is capable of meeting SWOT's demanding Ka-Band remote sensing requirements. One of the key aspects of this antenna development is to minimize the effect of the on-orbit thermal distortion to the antenna RF performance. An analysis process which includes: 1) the on-orbit thermal analysis to obtain the temperature distribution; 2) structural deformation analysis to get the geometry of the antenna surface; and 3) the RF performance with the given deformed antenna surface has been developed to accommodate the development of this antenna technology. The detailed analysis process and some analysis results will be presented and discussed by this paper.

  3. Plasmids of the pRM/pRF family occur in diverse Rickettsia species.

    PubMed

    Baldridge, Gerald D; Burkhardt, Nicole Y; Felsheim, Roderick F; Kurtti, Timothy J; Munderloh, Ulrike G

    2008-02-01

    The recent discoveries of the pRF and pRM plasmids of Rickettsia felis and R. monacensis have contravened the long-held dogma that plasmids are not present in the bacterial genus Rickettsia (Rickettsiales; Rickettsiaceae). We report the existence of plasmids in R. helvetica, R. peacockii, R. amblyommii, and R. massiliae isolates from ixodid ticks and in an R. hoogstraalii isolate from an argasid tick. R. peacockii and four isolates of R. amblyommii from widely separated geographic locations contained plasmids that comigrated with pRM during pulsed-field gel electrophoresis and larger plasmids with mobilities similar to that of pRF. The R. peacockii plasmids were lost during long-term serial passage in cultured cells. R. montanensis did not contain a plasmid. Southern blots showed that sequences similar to those of a DnaA-like replication initiator protein, a small heat shock protein 2, and the Sca12 cell surface antigen genes on pRM and pRF were present on all of the plasmids except for that of R. massiliae, which lacked the heat shock gene and was the smallest of the plasmids. The R. hoogstraalii plasmid was most similar to pRM and contained apparent homologs of proline/betaine transporter and SpoT stringent response genes on pRM and pRF that were absent from the other plasmids. The R. hoogstraalii, R. helvetica, and R. amblyommii plasmids contained homologs of a pRM-carried gene similar to a Nitrobacter sp. helicase RecD/TraA gene, but none of the plasmids hybridized with a probe derived from a pRM-encoded gene similar to a Burkholderia sp. transposon resolvase gene.

  4. RF cavity R&D at LBNL for the NLC damping rings, FY1999

    SciTech Connect

    Rimmer, R.A.; Corlett, J.N.; Koehler, G.; Li, D.; Hartman, N.; Rasson, J.; Saleh, T.

    1999-11-01

    This report contains a summary of the R&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.

  5. Measurement of RF electric field in high- β plasma using a Pockels detector in magnetosphere plasma confinement device RT-1

    NASA Astrophysics Data System (ADS)

    Mushiake, Toshiki; Nishiura, M.; Yoshida, Z.; Yano, Y.; Kawazura, Y.; Saitoh, H.; Yamasaki, M.; Kashyap, A.; Takahashi, N.; Nakatsuka, M.; Fukuyama, Atsushi

    2015-11-01

    The magnetosphere plasma confinement device RT-1 generates a dipole magnetic field that can confine high- β plasma by using a levitated superconducting coil. So far it is reported that high temperature electrons (up to 50keV) exist and that the local electron βe value exceeds more than 100%. However, the ion β value βi remains low in the present high- β state. To realize a high-βi state, we have started Ion Cyclotron Heating (ICH) experiments. For efficient ICH in a dipole topology, it is important to measure RF electric fields and characterize the propagation of RF waves in plasmas. On this viewpoint, we started direct measurement of local RF electric fields in RT-1 with a Pockels sensor system. A non-linear optical crystal in the Pockels sensor produces birefringence in an ambient electric field. The refractive index change of the birefringence is proportional to the applied electric field strength, which can be used to measure local electric fields. RF electric field distribution radiated from an ICH antenna was measured inside RT-1 in air, and was compared with numerical results calculated by TASK code. Results on the measurement of electric field distribution in high- β plasma and evaluation of the absorbed RF power into ions will be reported. Supported by JSPS KAKENHI Grant Numbers 23224014.

  6. L-band Photocathode RF gun at KEK-STF

    NASA Astrophysics Data System (ADS)

    Sugiyama, H.; Takahashi, Y.; Hayano, H.; Urakawa, J.; Kashiwagi, S.; Isoyama, G.; Kato, R.; Sugimoto, N.; Kuriki, M.

    2011-05-01

    The superconducting RF test facility (STF) in KEK is a facility to promote R&D of the International Linear Collider (ILC) cavities and cryomodule. L-band photocathode RF gun has been developed at KEK-STF as an electron beam source for cryomodule test scheduled in autumn of 2011. The RF cavity of the gun will be operated with a 1.3 GHz RF frequency, 1 msec RF pulse width, 5 Hz repetition rate at normal conductivity. The cavity was prepared by collaborative work with DESY and FNAL, and fabricated by FNAL. The RF conditioning of the cavity has been started since April 2010. A cesium telluride thin film as a photocathode material has been adopted, and the preparation equipment for cesium telluride has been newly designed and constructed. By using this new system, a fabrication and a performance estimation of the cesium telluride thin film as a photocathode are the next step of the research.

  7. EM modeling of RF drive in DTL tank 4

    SciTech Connect

    Kurennoy, Sergey S.

    2012-06-19

    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.

  8. Heating with waste heat

    SciTech Connect

    Beabout, R.W.

    1986-09-02

    Most of the power consumed in the gaseous diffusion process is converted into heat of compression, which is removed from the process gas and rejected into the atmosphere by recirculating cooling water over cooling towers. The water being handled through the X-333 and X-330 Process Buildings can be heated to 140 to 150/sup 0/F for heating use. The Gas Centrifuge Enrichment Plant is provided with a recirculating heating water (RHW) system which uses X-330 water and wasted heat. The RHW flow is diagrammed. (DLC)

  9. Quasicrystalline Beam Formation in RF Photoinjectors

    SciTech Connect

    Rosenzweig, J. B.; Dunning, M. P.; Hemsing, Erik; Marcus, G.; Marinelli, Agostino; Musumeci, Pietro; Pham, A.; Ferrario, M.

    2009-01-22

    The recent observation of coherent optical transition radiation at the LCLS has raised serious questions concerning the present model of beam dynamics in RF photoinjectors. We present here an analysis of what we term quasicrystalline beam formation. In this scenario, the low longitudinal temperature, in combination with strong acceleration and temporal rearrangement due to bending, allows the longitudinal beam dimension to become more regular, on the microscopic scale of optical wavelengths, than expected from equilibrium statistical properties. This beam distribution then may then display a strong degree of coherence in its optical transition radiation output. We discuss further experimental investigations of this phenomenon.

  10. RK-TBA prototype RF source

    SciTech Connect

    Houck, T.; Anderson, D.; Giordano, G.

    1996-04-11

    A prototype rf power source based on the Relativistic Klystron Two-Beam Accelerator (RK-TBA) concept is being constructed at the Lawrence Berkeley National Laboratory to study physics, engineering, and costing issues. The prototype is described and compared to a full scale design appropriate for driving the Next Linear Collider (NLC). Specific details of the induction core tests and pulsed power system are presented. The 1-MeV, 1.2-kA induction gun currently under construction is also described in detail.

  11. Silicon Technologies Adjust to RF Applications

    NASA Technical Reports Server (NTRS)

    Reinecke Taub, Susan; Alterovitz, Samuel A.

    1994-01-01

    Silicon (Si), although not traditionally the material of choice for RF and microwave applications, has become a serious challenger to other semiconductor technologies for high-frequency applications. Fine-line electron- beam and photolithographic techniques are now capable of fabricating silicon gate sizes as small as 0.1 micron while commonly-available high-resistivity silicon wafers support low-loss microwave transmission lines. These advances, coupled with the recent development of silicon-germanium (SiGe), arm silicon integrated circuits (ICs) with the speed required for increasingly higher-frequency applications.

  12. Computer control of rf at SLAC

    SciTech Connect

    Schwarz, H.D.

    1985-03-01

    The Stanford Linear Accelerator is presently upgraded for the SLAC Linear Collider project. The energy is to be increased from approximately 31 GeV to 50 GeV. Two electron beams and one positron beam are to be accelerated with high demands on the quality of the beams. The beam specifications are shown. To meet these specifications, all parameters influencing the beams have to be under tight control and continuous surveillance. This task is accomplished by a new computer system implemented at SLAC which has, among many other functions, control over rf accelerating fields. 13 refs., 8 figs., 2 tabs.

  13. RF Transmission Lines on Silicon Substrates

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.

    1999-01-01

    A review of RF transmission lines on silicon substrates is presented. Through measurements and calculated results, it is shown that attenuation is dominated by conductor loss if silicon substrates with a resistivity greater than 2500 Ohm-cm are used. Si passivation layers affect the transmission line attenuation; however, measured results demonstrate that passivation layers do not necessarily increase attenuation. If standard, low resistivity Si wafers must be used, alternative transmission lines such as thin film microstrip and Co-Planar Waveguide (CPW) on thick polyimide layers must be used. Measured results presented here show that low loss per unit length is achievable with these transmission lines.

  14. Dual RF Astrodynamic GPS Orbital Navigator Satellite

    NASA Technical Reports Server (NTRS)

    Kanipe, David B.; Provence, Robert Steve; Straube, Timothy M.; Reed, Helen; Bishop, Robert; Lightsey, Glenn

    2009-01-01

    Dual RF Astrodynamic GPS Orbital Navigator Satellite (DRAGONSat) will demonstrate autonomous rendezvous and docking (ARD) in low Earth orbit (LEO) and gather flight data with a global positioning system (GPS) receiver strictly designed for space applications. ARD is the capability of two independent spacecraft to rendezvous in orbit and dock without crew intervention. DRAGONSat consists of two picosatellites (one built by the University of Texas and one built by Texas A and M University) and the Space Shuttle Payload Launcher (SSPL); this project will ultimately demonstrate ARD in LEO.

  15. CLIC RF High Power Production Testing Program

    SciTech Connect

    Syratchev, I.; Riddone, G.; Tantawi, S.G.; /SLAC

    2011-11-02

    The CLIC Power Extraction and Transfer Structure (PETS) is a passive microwave device in which bunches of the drive beam interact with the impedance of the periodically loaded waveguide and generate RF power for the main linac accelerating structure. The demands on the high power production ({approx} 150 MW) and the needs to transport the 100 A drive beam for about 1 km without losses, makes the PETS design rather unique and the operation very challenging. In the coming year, an intense PETS testing program will be implemented. The target is to demonstrate the full performance of the PETS operation. The testing program overview and test results available to date are presented.

  16. Rf power sources for linear colliders

    SciTech Connect

    Allen, M.A.; Callin, R.S.; Caryotakis, G.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Farkas, Z.D.; Fowkes, W.R.; Hoag, H.A.; Feinstein, J.; Ko, K.; Koontz, R.F.; Kroll, N.M.; Lavine, T.L.; Lee, T.G.; Loew, G.A.; Miller, R.H.; Nelson, E.M.; Ruth, R.D.; Vlieks, A.E.; Wang, J.W.; Wilson, P.B. ); Boyd, J.K.; Houk, T.; Ryne, R.D.; Westenskow, G.A.; Yu, S.S. (Lawrence Live

    1990-06-01

    The next generation of linear colliders requires peak power sources of over 200 MW per meter at frequencies above 10 GHz at pulse widths of less than 100 nsec. Several power sources are under active development, including a conventional klystron with rf pulse compression, a relativistic klystron (RK) and a crossed-field amplifier. Power from one of these has energized a 0.5 meter two- section High Gradient Accelerator (HGA) and accelerated a beam at over 80 MeV meter. Results of tests with these experimental devices are presented here.

  17. Status of Nb-Pb superconducting RF-gun cavities

    SciTech Connect

    J. Sekutowicz; J. Iversen; D. Klinke; D. Kostin; W. Möller; A. Muhs; P. Kneisel; J. Smedley; T. Rao; P. Strzyżewski; Z. Li; K. Ko; L. Xiao; R. Lefferts; A. Lipski; M. Ferrario

    2007-06-01

    We report on the progress in the status of an electron RF-gun made of two superconductors: niobium and lead. The presented design combines the advantages of the RF performance of bulk niobium superconducting cavities and the reasonably high quantum efficiency of lead. Measured values of quantum efficiency for lead at 2K and the RF-performance of three half-cell niobium cavities with the lead spot exposed to high electric fields are reported in this contribution.

  18. Design of vertical packaging technology for RF MEMS switch

    NASA Astrophysics Data System (ADS)

    Bansal, Deepak; Sharma, Akshdeep; Kaur, Maninder; Rangra, K. J.

    2012-10-01

    Wafer-level micro-encapsulation is an innovative, low-cost, wafer-level packaging method for encapsulating RF MEMS switches. This article presents an approach for design and processing steps related to encapsulation of individual RF components e.g. CPW, RF MEMS switches, in view of the variation in performance subsequent to packaging. Bottom contact vertical packaging is more prone to misalignment margin and easy to make connections. Cavity height of 30 µm is optimized for bottom contact vertical packaging.

  19. Active high-power RF switch and pulse compression system

    DOEpatents

    Tantawi, Sami G.; Ruth, Ronald D.; Zolotorev, Max

    1998-01-01

    A high-power RF switching device employs a semiconductor wafer positioned in the third port of a three-port RF device. A controllable source of directed energy, such as a suitable laser or electron beam, is aimed at the semiconductor material. When the source is turned on, the energy incident on the wafer induces an electron-hole plasma layer on the wafer, changing the wafer's dielectric constant, turning the third port into a termination for incident RF signals, and. causing all incident RF signals to be reflected from the surface of the wafer. The propagation constant of RF signals through port 3, therefore, can be changed by controlling the beam. By making the RF coupling to the third port as small as necessary, one can reduce the peak electric field on the unexcited silicon surface for any level of input power from port 1, thereby reducing risk of damaging the wafer by RF with high peak power. The switch is useful to the construction of an improved pulse compression system to boost the peak power of microwave tubes driving linear accelerators. In this application, the high-power RF switch is placed at the coupling iris between the charging waveguide and the resonant storage line of a pulse compression system. This optically controlled high power RF pulse compression system can handle hundreds of Megawatts of power at X-band.

  20. Rf system considerations for a large hadron collider

    SciTech Connect

    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.