Development of the heat sink structure of a beam dump for the proton accelerator

International Nuclear Information System (INIS)

Maeng, W. Y.; Gil, C. S.; Kim, J. H.; Kim, D. H.

2007-01-01

The beam dump is the essential component for the good beam quality and the reliable performance of the proton accelerator. The beam dump for a 20 MeV and 20 mA proton accelerator was designed and manufactured in this study. The high heats deposited, and the large amount of radioactivity produced in beam dump should be reduced by the proper heat sink structure. The heat source by the proton beam of 20 MeV and 20 mA was calculated. The radioactivity assessments of the beam dump were carried out for the economic shielding design with safety. The radioactivity by the protons and secondary neutrons in designed beam dump were calculated in this sturdy. The effective engineering design for the beam dump cooling was performed, considering the mitigation methods of the deposited heats with small angle, the power densities with the stopping ranges in the materials and the heat distributions in the beam dump. The heat sink structure of the beam dump was designed to meet the accelerator characteristics by placing two plates of 30 cm by 60 cm at an angle of 12 degree. The highest temperatures of the graphite, copper, and copper faced by cooling water were designed to be 223 degree, 146 degree, and 85 degree, respectively when the velocity of cooling water was 3 m/s. The heat sink structure was manufactured by the brazing graphite tiles to a copper plate with the filler alloy of Ti-Cu-Ag. The brazing procedure was developed. The tensile stress of the graphite was less than 75% of a maximum tensile stress during the accelerator operation based on the analysis. The safety analyses for the commissioning of the accelerator operation were also performed. The specimens from the brazed parts of beam dump structure were made to identify manufacturing problems. The soundness of the heat sink structure of the beam dump was confirmed by the fatigue tests of the brazed specimens of the graphite-copper tile components with the repetitive heating and cooling. The heat sink structure developed

OpenFOAM Modeling of Particle Heating and Acceleration in Cold Spraying

Science.gov (United States)

Leitz, K.-H.; O'Sullivan, M.; Plankensteiner, A.; Kestler, H.; Sigl, L. S.

2018-01-01

In cold spraying, a powder material is accelerated and heated in the gas flow of a supersonic nozzle to velocities and temperatures that are sufficient to obtain cohesion of the particles to a substrate. The deposition efficiency of the particles is significantly determined by their velocity and temperature. Particle velocity correlates with the amount of kinetic energy that is converted to plastic deformation and thermal heating. The initial particle temperature significantly influences the mechanical properties of the particle. Velocity and temperature of the particles have nonlinear dependence on the pressure and temperature of the gas at the nozzle entrance. In this contribution, a simulation model based on the reactingParcelFoam solver of OpenFOAM is presented and applied for an analysis of particle velocity and temperature in the cold spray nozzle. The model combines a compressible description of the gas flow in the nozzle with a Lagrangian particle tracking. The predictions of the simulation model are verified based on an analytical description of the gas flow, the particle acceleration and heating in the nozzle. Based on experimental data, the drag model according to Plessis and Masliyah is identified to be best suited for OpenFOAM modeling particle heating and acceleration in cold spraying.

The effects of linear accelerations on the maximum heat transfer capacity of micro pipes with triangular grooves

International Nuclear Information System (INIS)

Shokouhmand, H.; Kahrobaian, A.; Tabandeh, N.; Jalilvand, A.

2002-01-01

Micro heat pipes are widely used for the thermal control of spacecraft and their electronic components. In this paper the influence of linear accelerations in micro grooves has been studied. A mathematical model for predicating the minimum meniscus radius and the maximum heat transport in triangular groove under the influence of linear acceleration is presented and method for determining the theoretical minimum meniscus radius is developed. It is shown that both, the direction and the magnitude of the acceleration have a great effect upon heat transfer capability of micro heat pipes. The analysis presented here provides a mechanism where by the groove geometry can be optimized with respect to the length of the heat pipe and direction and magnitude of linear acceleration

Heating of microprotrusions in accelerating structures

Directory of Open Access Journals (Sweden)

A. C. Keser

2013-09-01

Full Text Available The thermal and field emission of electrons from protrusions on metal surfaces is a possible limiting factor on the performance and operation of high-gradient room temperature accelerator structures. We present here the results of extensive numerical simulations of electrical and thermal behavior of protrusions. We unify the thermal and field emission in the same numerical framework, describe bounds for the emission current and geometric enhancement, then we calculate the Nottingham and Joule heating terms and solve the heat equation to characterize the thermal evolution of emitters under rf electric field. Our findings suggest that heating is entirely due to the Nottingham effect. The time dependence of the rf field leads to a time dependent tip temperature with excursion that depends weakly on rf frequency. We build a phenomenological model to account for the effect of space charge and show that space charge eliminates the possibility of copper tip melting for tips with radii less than 10  μm with vacuum fields on their surface less than 12  GV/m, and for rf frequencies above 1 GHz.

Critical heat flux of forced convection boiling in an oscilating acceleration field. Pt. 1

International Nuclear Information System (INIS)

Otsuji, T.; Kurosawa, A.

1982-01-01

The influence of periodically varying acceleration on critical heat flux (CHF) of Freon-113 flowing upward in a uniformly heated vertical annular channel has been studied experimentally. The freon loop was oscillated vertically to determine the ratio of CHF in the oscillating acceleration field to the corresponding stationary value. The amplitude of inlet flow oscillation induced by variation of acceleration, which causes early CHF, is proportional to the acceleration amplitude. The dependence of inlet flow rate on the oscillating acceleration decreases with increasing inlet subcooling, and no oscillation of inlet flow is observed in the case of negative exit quality (subcooled boiling). Nevertheless the degradation of CHF is more remarkable in the low quality region. This result suggests the necessity to introduce an other mechanism of early CHF than flow oscillation. (orig.)

Experimental study of ion heating and acceleration during magnetic reconnection

Energy Technology Data Exchange (ETDEWEB)

Hsu, S.C.

2000-01-28

This dissertation reports an experimental study of ion heating and acceleration during magnetic reconnection, which is the annihilation and topological rearrangement of magnetic flux in a conductive plasma. Reconnection is invoked often to explain particle heating and acceleration in both laboratory and naturally occurring plasmas. However, a simultaneous account of reconnection and its associated energy conversion has been elusive due to the extreme inaccessibility of reconnection events, e.g. in the solar corona, the Earth's magnetosphere, or in fusion research plasmas. Experiments for this work were conducted on MRX (Magnetic Reconnection Experiment), which creates a plasma environment allowing the reconnection process to be isolated, reproduced, and diagnosed in detail. Key findings of this work are the identification of local ion heating during magnetic reconnection and the determination that non-classical effects must provide the heating mechanism. Measured ion flows are sub-Alfvenic and can provide only slight viscous heating, and classical ion-electron interactions can be neglected due to the very long energy equipartition time. The plasma resistivity in the reconnection layer is seen to be enhanced over the classical value, and the ion heating is observed to scale with the enhancement factor, suggesting a relationship between the magnetic energy dissipation mechanism and the ion heating mechanism. The observation of non-classical ion heating during reconnection has significant implications for understanding the role played by non-classical dissipation mechanisms in generating fast reconnection. The findings are relevant for many areas of space and laboratory plasma research, a prime example being the currently unsolved problem of solar coronal heating. In the process of performing this work, local measurements of ion temperature and flows in a well-characterized reconnection layer were obtained for the first time in either laboratory or observational

Experimental study of ion heating and acceleration during magnetic reconnection

International Nuclear Information System (INIS)

Hsu, S.C.

2000-01-01

This dissertation reports an experimental study of ion heating and acceleration during magnetic reconnection, which is the annihilation and topological rearrangement of magnetic flux in a conductive plasma. Reconnection is invoked often to explain particle heating and acceleration in both laboratory and naturally occurring plasmas. However, a simultaneous account of reconnection and its associated energy conversion has been elusive due to the extreme inaccessibility of reconnection events, e.g. in the solar corona, the Earth's magnetosphere, or in fusion research plasmas. Experiments for this work were conducted on MRX (Magnetic Reconnection Experiment), which creates a plasma environment allowing the reconnection process to be isolated, reproduced, and diagnosed in detail. Key findings of this work are the identification of local ion heating during magnetic reconnection and the determination that non-classical effects must provide the heating mechanism. Measured ion flows are sub-Alfvenic and can provide only slight viscous heating, and classical ion-electron interactions can be neglected due to the very long energy equipartition time. The plasma resistivity in the reconnection layer is seen to be enhanced over the classical value, and the ion heating is observed to scale with the enhancement factor, suggesting a relationship between the magnetic energy dissipation mechanism and the ion heating mechanism. The observation of non-classical ion heating during reconnection has significant implications for understanding the role played by non-classical dissipation mechanisms in generating fast reconnection. The findings are relevant for many areas of space and laboratory plasma research, a prime example being the currently unsolved problem of solar coronal heating. In the process of performing this work, local measurements of ion temperature and flows in a well-characterized reconnection layer were obtained for the first time in either laboratory or observational

Investigation of pellet acceleration by an arc heated gas gun

International Nuclear Information System (INIS)

Andersen, P.; Andersen, S.A.; Bundgaard, J.; Baekmark, L.; Hansen, B.H.; Jensen, V.O.; Kossek, H.; Michelsen, P.K.; Nordskov, A.; Sass, B.; Soerensen, H.; Weisberg, K.V.

1987-06-01

This report describes work on pellet acceleration by means of an arc heated gas gun. The work is a continuation of the work described in RISO-M-2536. The aim of the work is to obtain velocities well above 2 km/s for 3.2 mm diameter deuterium pellets. By means of a cryogenic arc chamber in which the hydrogen propellant is pre-condensed, extruded deutetrium pellets are accelerated up to a maximum velocity of 1.93 km/s. When increasing the energy input to the arc in order to increase the pellet velocity further the heat input to the extrusion/punching pellet loading mechanism was found to be critical: preparation of pellets became difficult and cooling times between shots became inconveniently long. In order to circumvent this problems the concept of a room temperature hydrogen propellant pellet fed arc chamber was proposed. Preliminary results from acceleration of polyurethane pellets with this arc chamber are described as well as the work of developing of feed pellet guns for this chamber. Finally the report describes design consideration for a high pressure propellant pellet fed arc chamber together with preliminary results obtained with a proto-type arc chamber. (author)

Joule heating and runaway electron acceleration in a solar flare

Science.gov (United States)

Holman, Gordon D.; Kundu, Mukul R.; Kane, Sharad R.

1989-01-01

The hard and soft x ray and microwave emissions from a solar flare (May 14, 1980) were analyzed and interpreted in terms of Joule heating and runaway electron acceleration in one or more current sheets. It is found that all three emissions can be generated with sub-Dreicer electric fields. The soft x ray emitting plasma can only be heated by a single current sheet if the resistivity in the sheet is well above the classical, collisional resistivity of 10(exp 7) K, 10(exp 11)/cu cm plasma. If the hard x ray emission is from thermal electrons, anomalous resistivity or densities exceeding 3 x 10(exp 12)/cu cm are required. If the hard x ray emission is from nonthermal electrons, the emissions can be produced with classical resistivity in the current sheets if the heating rate is approximately 4 times greater than that deduced from the soft x ray data (with a density of 10(exp 10)/cu cm in the soft x ray emitting region), if there are at least 10(exp 4) current sheets, and if the plasma properties in the sheets are characteristic of the superhot plasma observed in some flares by Lin et al., and with Hinotori. Most of the released energy goes directly into bulk heating, rather than accelerated particles.

Selenide isotope generator for the Galileo Mission. Axially-grooved heat pipe: accelerated life test results

International Nuclear Information System (INIS)

1979-08-01

The results through SIG/Galileo contract close-out of accelerated life testing performed from June 1978 to June 1979 on axially-grooved, copper/water heat pipes are presented. The primary objective of the test was to determine the expected lifetime of axially-grooved copper/water heat pipes. The heat pipe failure rate, due to either a leak or a build-up of non-condensible gas, was determined. The secondary objective of the test was to determine the effects of time and temperature on the thermal performance parameters relevant to long-term (> 50,000 h) operation on a space power generator. The results showed that the gas generation rate appears to be constant with time after an initial sharp rise although there are indications that it drops to approximately zero beyond approx. 2000 h. During the life test, the following pipe-hours were accumulated: 159,000 at 125 0 C, 54,000 at 165 0 C, 48,000 at 185 0 C, and 8500 at 225 0 C. Heated hours per pipe ranged from 1000 to 7500 with an average of 4720. Applying calculated acceleration factors yields the equivalent of 930,000 pipe-h at 125 0 C. Including the accelerated hours on vendor tested pipes raises this number to 1,430,000 pipe-hours at 125 0 C. It was concluded that, for a heat pipe temperature of 125 0 C and a mission time of 50,000 h, the demonstrated heat pipe reliability is between 80% (based on 159,000 actual pipe-h at 125 0 C) and 98% (based on 1,430,000 accelerated pipe-h at 125 0 C). Measurements indicate some degradation of heat transfer with time, but no detectable degradation of heat transport

Heating and acceleration of solar wind ions by turbulent wave spectrum in inhomogeneous expanding plasma

Energy Technology Data Exchange (ETDEWEB)

Ofman, Leon, E-mail: Leon.Ofman@nasa.gov [Department of Physics, The Catholic University of America, Washington, DC (United States); NASA Goddard Space Flight Center, Greenbelt, MD (United States); Visiting, Department of Geosciences, Tel Aviv University, Tel Aviv (Israel); Ozak, Nataly [Centre for mathematical Plasma Astrophysics, KU Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Viñas, Adolfo F. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

2016-03-25

Near the Sun (< 10R{sub s}) the acceleration, heating, and propagation of the solar wind are likely affected by the background inhomogeneities of the magnetized plasma. The heating and the acceleration of the solar wind ions by turbulent wave spectrum in inhomogeneous plasma is studied using a 2.5D hybrid model. The hybrid model describes the kinetics of the ions, while the electrons are modeled as massless neutralizing fluid in an expanding box approach. Turbulent magnetic fluctuations dominated by power-law frequency spectra, which are evident from in-situ as well as remote sensing measurements, are used in our models. The effects of background density inhomogeneity across the magnetic field on the resonant ion heating are studied. The effect of super-Alfvénic ion drift on the ion heating is investigated. It is found that the turbulent wave spectrum of initially parallel propagating waves cascades to oblique modes, and leads to enhanced resonant ion heating due to the inhomogeneity. The acceleration of the solar wind ions is achieved by the parametric instability of large amplitude waves in the spectrum, and is also affected by the inhomogeneity. The results of the study provide the ion temperature anisotropy and drift velocity temporal evolution due to relaxation of the instability. The non-Maxwellian velocity distribution functions (VDFs) of the ions are modeled in the inhomogeneous solar wind plasma in the acceleration region close to the Sun.

Electron Heating and Acceleration in a Reconnecting Magnetotail

Science.gov (United States)

El-Alaoui, M.; Zhou, M.; Lapenta, G.; Berchem, J.; Richard, R. L.; Schriver, D.; Walker, R. J.

2017-12-01

Electron heating and acceleration in the magnetotail have been investigated intensively. A major site for this process is the reconnection region. However, where and how the electrons are accelerated in a realistic three-dimensional X-line geometry is not fully understood. In this study, we employed a three-dimensional implicit particle-in-cell (iPIC3D) simulation and large-scale kinetic (LSK) simulation to address these problems. We modeled a magnetotail reconnection event observed by THEMIS in an iPIC3D simulation with initial and boundary conditions given by a global magnetohydrodynamic (MHD) simulation of Earth's magnetosphere. The iPIC3D simulation system includes the region of fast outflow emanating from the reconnection site that drives dipolarization fronts. We found that current sheet electrons exhibit elongated (cigar-shaped) velocity distributions with a higher parallel temperature. Using LSK we then followed millions of test electrons using the electromagnetic fields from iPIC3D. We found that magnetotail reconnection can generate power law spectra around the near-Earth X-line. A significant number of electrons with energies higher than 50 keV are produced. We identified several acceleration mechanisms at different locations that were responsible for energizing these electrons: non-adiabatic cross-tail drift, betatron and Fermi acceleration. Relative contributions to the energy gain of these high energy electrons from the different mechanisms will be discussed.

Experimental study on the critical heat flux in a varying acceleration field, (1)

International Nuclear Information System (INIS)

Kusunoki, Tsuyoshi; Yokomura, Takeyoshi; Otsuji, Tomoo; Ikawa, Masahiro; Kurosawa, Akira.

1988-12-01

It is very important for the thermohydraulic design and for the safety assesement of marine reactors, to understand the effect of varying acceleration induced by ship motion on critical heart flux. The purpose of this joint study is to examine quantitatively the influence of varying acceleration on the behavior of bubbles. In the experiment, FREON-113 was used as working fluid. This report describes some experimental results; measurements of void fraction and bubble velocity near the heat transfer surface, measurement of bubble size under stationary acceleration field and observation of bubble behavior under varying acceleration field. (author)

Characterizing a Model of Coronal Heating and Solar Wind Acceleration Based on Wave Turbulence.

Science.gov (United States)

Downs, C.; Lionello, R.; Mikic, Z.; Linker, J.; Velli, M.

2014-12-01

Understanding the nature of coronal heating and solar wind acceleration is a key goal in solar and heliospheric research. While there have been many theoretical advances in both topics, including suggestions that they may be intimately related, the inherent scale coupling and complexity of these phenomena limits our ability to construct models that test them on a fundamental level for realistic solar conditions. At the same time, there is an ever increasing impetus to improve our spaceweather models, and incorporating treatments for these processes that capture their basic features while remaining tractable is an important goal. With this in mind, I will give an overview of our exploration of a wave-turbulence driven (WTD) model for coronal heating and solar wind acceleration based on low-frequency Alfvénic turbulence. Here we attempt to bridge the gap between theory and practical modeling by exploring this model in 1D HD and multi-dimensional MHD contexts. The key questions that we explore are: What properties must the model possess to be a viable model for coronal heating? What is the influence of the magnetic field topology (open, closed, rapidly expanding)? And can we simultaneously capture coronal heating and solar wind acceleration with such a quasi-steady formulation? Our initial results suggest that a WTD based formulation performs adequately for a variety of solar and heliospheric conditions, while significantly reducing the number of free parameters when compared to empirical heating and solar wind models. The challenges, applications, and future prospects of this type of approach will also be discussed.

Heating and Acceleration of Solar Wind Ions by Turbulent Wave Spectrum in Inhomogeneous Expanding Plasma

Science.gov (United States)

Ofman, Leon; Ozak, Nataly; Vinas, Adolfo F.

2016-01-01

Near the Sun (plasma. The heating and the acceleration of the solar wind ions by turbulent wave spectrum in inhomogeneous plasma is studied using a 2.5D hybrid model. The hybrid model describes the kinetics of the ions, while the electrons are modeled as massless neutralizing fluid in an expanding box approach. Turbulent magnetic fluctuations dominated by power-law frequency spectra, which are evident from in-situ as well as remote sensing measurements, are used in our models. The effects of background density inhomogeneity across the magnetic field on the resonant ion heating are studied. The effect of super- Alfvenic ion drift on the ion heating is investigated. It is found that the turbulent wave spectrum of initially parallel propagating waves cascades to oblique modes, and leads to enhanced resonant ion heating due to the inhomogeneity. The acceleration of the solar wind ions is achieved by the parametric instability of large amplitude waves in the spectrum, and is also affected by the inhomogeneity. The results of the study provide the ion temperature anisotropy and drift velocity temporal evolution due to relaxation of the instability. The non-Maxwellian velocity distribution functions (VDFs) of the ions are modeled in the inhomogeneous solar wind plasma in the acceleration region close to the Sun.

Transport of laser accelerated proton beams and isochoric heating of matter

International Nuclear Information System (INIS)

Roth, M; Alber, I; Guenther, M; Harres, K; Bagnoud, V; Brown, C; Gregori, G; Clarke, R; Heathcote, R; Li, B; Daido, H; Fernandez, J; Flippo, K; Gaillard, S; Gauthier, C; Glenzer, S; Kritcher, A; Kugland, N; LePape, S; Makita, M

2010-01-01

The acceleration of intense proton and ion beams by ultra-intense lasers has matured to a point where applications in basic research and technology are being developed. Crucial for harvesting the unmatched beam parameters driven by the relativistic electron sheath is the precise control of the beam. We report on recent experiments using the PHELIX laser at GSI, the VULCAN laser at RAL and the TRIDENT laser at LANL to control and use laser accelerated proton beams for applications in high energy density research. We demonstrate efficient collimation of the proton beam using high field pulsed solenoid magnets, a prerequisite to capture and transport the beam for applications. Furthermore we report on two campaigns to use intense, short proton bunches to isochorically heat solid targets up to the warm dense matter state. The temporal profile of the proton beam allows for rapid heating of the target, much faster than the hydrodynamic response time thereby creating a strongly coupled plasma at solid density. The target parameters are then probed by X-ray Thomson scattering (XRTS) to reveal the density and temperature of the heated volume. This combination of two powerful techniques developed during the past few years allows for the generation and investigation of macroscopic samples of matter in states present in giant planets or the interior of the earth.

Transport of laser accelerated proton beams and isochoric heating of matter

Energy Technology Data Exchange (ETDEWEB)

Roth, M; Alber, I; Guenther, M; Harres, K [Inst. fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Bagnoud, V [GSI Helmholtzzentrum f. Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Brown, C; Gregori, G [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Clarke, R; Heathcote, R; Li, B [STFC, Rutherford Appleton Laboratory, Chilton, Didcot, OX14 OQX (United Kingdom); Daido, H [Photo Medical Research Center, JAEA, Kizugawa-City, Kyoto 619-0215 (Japan); Fernandez, J; Flippo, K; Gaillard, S; Gauthier, C [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Glenzer, S; Kritcher, A; Kugland, N; LePape, S [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Makita, M, E-mail: markus.roth@physik.tu-darmstadt.d [School of Mathematics and Physics, Queen' s University of Belfast, Belfast BT7 1NN (United Kingdom)

2010-08-01

The acceleration of intense proton and ion beams by ultra-intense lasers has matured to a point where applications in basic research and technology are being developed. Crucial for harvesting the unmatched beam parameters driven by the relativistic electron sheath is the precise control of the beam. We report on recent experiments using the PHELIX laser at GSI, the VULCAN laser at RAL and the TRIDENT laser at LANL to control and use laser accelerated proton beams for applications in high energy density research. We demonstrate efficient collimation of the proton beam using high field pulsed solenoid magnets, a prerequisite to capture and transport the beam for applications. Furthermore we report on two campaigns to use intense, short proton bunches to isochorically heat solid targets up to the warm dense matter state. The temporal profile of the proton beam allows for rapid heating of the target, much faster than the hydrodynamic response time thereby creating a strongly coupled plasma at solid density. The target parameters are then probed by X-ray Thomson scattering (XRTS) to reveal the density and temperature of the heated volume. This combination of two powerful techniques developed during the past few years allows for the generation and investigation of macroscopic samples of matter in states present in giant planets or the interior of the earth.

Accelerated life tests of specimen heat pipe from Communication Technology Satellite (CTS) project

Science.gov (United States)

Tower, L. K.; Kaufman, W. B.

1977-01-01

A gas-loaded variable conductance heat pipe of stainless steel with methanol working fluid identical to one now on the CTS satellite was life tested in the laboratory at accelerated conditions for 14 200 hours, equivalent to about 70 000 hours at flight conditions. The noncondensible gas inventory increased about 20 percent over the original charge. The observed gas increase is estimated to increase operating temperature by about 2.2 C, insufficient to harm the electronic gear cooled by the heat pipes in the satellite. Tests of maximum heat input against evaporator elevation agree well with the manufacturer's predictions.

Silicon Carbide (SiC) Device and Module Reliability, Performance of a Loop Heat Pipe Subjected to a Phase-Coupled Heat Input to an Acceleration Field

Science.gov (United States)

2016-05-01

AFRL-RQ-WP-TR-2016-0108 SILICON CARBIDE (SiC) DEVICE AND MODULE RELIABILITY Performance of a Loop Heat Pipe Subjected to a Phase-Coupled...CARBIDE (SiC) DEVICE AND MODULE RELIABILITY Performance of a Loop Heat Pipe Subjected to a Phase-Coupled Heat Input to an Acceleration Field 5a...Shukla, K., “Thermo-fluid dynamics of Loop Heat Pipe Operation,” International Communications in Heat and Mass Transfer , Vol. 35, No. 8, 2008, pp

Heat generation by eddy currents in a shell of superconducting bus-bars for SIS100 particle accelerator at FAIR

Directory of Open Access Journals (Sweden)

Tomków Łukasz

2017-12-01

Full Text Available Superconducting magnets in the SIS100 particle accelerator require the supply of liquid helium and electric current. Both are transported with by-pass lines designed at Wrocław University of Technology. Bus-bars used to transfer an electric current between the sections of the accelerator will be encased in a steel shell. Eddy currents are expected to appear in the shell during fast-ramp operation of magnets. Heat generation, which should be limited in any cryogenic system, will appear in the shell. In this work the amount of heat generated is assessed depending on the geometry of an assembly of the bus-bars and the shell. Numerical and analytical calculations are described. It was found that heat generation in the shell is relatively small when compared to other sources present in the accelerator and its value strongly depends on the geometry of the shell. The distribution of eddy currents and generated heat for different geometrical options are presented. Based on the results of the calculations the optimal design is proposed.

Acceleration to high velocities and heating by impact using Nike KrF lasera)

Science.gov (United States)

Karasik, Max; Weaver, J. L.; Aglitskiy, Y.; Watari, T.; Arikawa, Y.; Sakaiya, T.; Oh, J.; Velikovich, A. L.; Zalesak, S. T.; Bates, J. W.; Obenschain, S. P.; Schmitt, A. J.; Murakami, M.; Azechi, H.

2010-05-01

The Nike krypton fluoride laser [S. P. Obenschain, S. E. Bodner, D. Colombant, et al., Phys. Plasmas 3, 2098 (1996)] is used to accelerate planar plastic foils to velocities that for the first time reach 1000 km/s. Collision of the highly accelerated deuterated polystyrene foil with a stationary target produces ˜Gbar shock pressures and results in heating of the foil to thermonuclear temperatures. The impact conditions are diagnosed using DD fusion neutron yield, with ˜106 neutrons produced during the collision. Time-of-flight neutron detectors are used to measure the ion temperature upon impact, which reaches 2-3 keV.

Salicylic acid alleviates decreases in photosynthesis under heat stress and accelerates recovery in grapevine leaves

Directory of Open Access Journals (Sweden)

Cheng Jian-Shan

2010-02-01

Full Text Available Abstract Background Although the effect of salicylic acid (SA on photosynthesis of plants including grapevines has been investigated, very little is yet known about the effects of SA on carbon assimilation and several components of PSII electron transport (donor side, reaction center and acceptor side. In this study, the impact of SA pretreatment on photosynthesis was evaluated in the leaves of young grapevines before heat stress (25°C, during heat stress (43°C for 5 h, and through the following recovery period (25°C. Photosynthetic measures included gas exchange parameters, PSII electron transport, energy dissipation, and Rubisco activation state. The levels of heat shock proteins (HSPs in the chloroplast were also investigated. Results SA did not significantly (P Pn of leaves before heat stress. But, SA did alleviate declines in Pn and Rubisco activition state, and did not alter negative changes in PSII parameters (donor side, acceptor side and reaction center QA under heat stress. Following heat treatment, the recovery of Pn in SA-treated leaves was accelerated compared with the control (H2O-treated leaves, and, donor and acceptor parameters of PSII in SA-treated leaves recovered to normal levels more rapidly than in the controls. Rubisco, however, was not significantly (P Conclusion SA pretreatment alleviated the heat stress induced decrease in Pn mainly through maintaining higher Rubisco activition state, and it accelerated the recovery of Pn mainly through effects on PSII function. These effects of SA may be related in part to enhanced levels of HSP21.

The generation of intense heat fluxes by electron bombardment to evaluate the use of swirl flow in the cooling of accelerator targets

International Nuclear Information System (INIS)

Genis, G.J.

1985-11-01

The thermal performance of isotope production targets for accelerators has been shown to be the limiting factor with regard to the cost of isotopes and the specific activity achievable. To allow the investigation of basic aspects of target cooling and the evaluation of certain target concepts off-line from accelerators, an electron bombardment system, including a radial electron accelerator (REA) in a diode configuration, was developed as heat source. Methods were developed to characterise the performance of the REA to supply a homogeneous heat flux to an axial target by which a technique for the construction of thermocouple placement holes in the body of the target can be evaluated from the measured temperatures. Having identified high velocity swirl flow as the most suitable technique to enhance the convective heat transfer in targets, experiments were conducted to determine the heat-transfer coefficient at high heat fluxes to high velocity swirl flow. The heat-transfer results substantiate the advantages of swirl flow for target cooling. Different correlations obtained indicate the importance of using the film properties instead of the bulk coolant properties in correlations and identify centrifugal convection as one of the most important heat transfer mechanisms in swirl flow

Acceleration to high velocities and heating by impact using Nike KrF laser

International Nuclear Information System (INIS)

Karasik, Max; Weaver, J. L.; Velikovich, A. L.; Zalesak, S. T.; Bates, J. W.; Obenschain, S. P.; Schmitt, A. J.; Aglitskiy, Y.; Watari, T.; Arikawa, Y.; Sakaiya, T.; Murakami, M.; Azechi, H.; Oh, J.

2010-01-01

The Nike krypton fluoride laser [S. P. Obenschain, S. E. Bodner, D. Colombant, et al., Phys. Plasmas 3, 2098 (1996)] is used to accelerate planar plastic foils to velocities that for the first time reach 1000 km/s. Collision of the highly accelerated deuterated polystyrene foil with a stationary target produces ∼Gbar shock pressures and results in heating of the foil to thermonuclear temperatures. The impact conditions are diagnosed using DD fusion neutron yield, with ∼10 6 neutrons produced during the collision. Time-of-flight neutron detectors are used to measure the ion temperature upon impact, which reaches 2-3 keV.

Radiation effects on heat transfer in heat exchangers, (2)

International Nuclear Information System (INIS)

Mori, Yasuo; Watanabe, Kenji; Taira, Tatsuji.

1980-01-01

In a high temperature gas-cooled reactor system, in which the working fluid exchanges heat at high temperature near 1000 deg C, the heat transfer acceleration by positively utilizing the radiation heat transfer between solid surfaces should be considered. This paper reports on the results of experiment and analysis for the effects of radiant heat on the heat transfer performance at elevated temperature by applying the heat transfer-accelerating method using radiators to the heat exchanger with tube bundle composed of two channels of heating and heated sides. As the test heat exchangers, a parallel counter flow exchanger and the cross flow exchanger simulating helical tubes were employed, and the results studied on the characteristics of each heat exchanger are described. The plates placed in parallel to flow in every space of the tube bundle arranged in a matrix were used as the heat transfer accelerator. The effects of acceleration with the plates were the increase of heat transmission from 12 to 24% and 12 to 38% in the parallel flow and cross flow heat exchangers, respectively. Also, it was clarified that the theoretical analysis, in which it was assumed that the region within pitch S and two radiator plates, with a heat-transferring tube placed at the center, is the minimum domain for calculation, and that the heat exchange by radiation occurs only between the domain and the adjacent domains, can estimate the heat transfer-accelerating effect and the temperature distribution in a heat exchanger with sufficient accuracy. (Wakatsuki, Y.)

Modification de la surface du cuivre par implantation ionique par source plasma (IISP): applications à l’érosion cathodique dans les systèmes à arcs

OpenAIRE

Roy, F

2006-01-01

L’érosion cathodique est un phénomène bien connu qui limite la durée de vie de l’électrode négative dans les systèmes à arcs. Dans le présent mémoire, nous avons tenté de voir si la formation de précipités nanométriques d’oxyde de cuivre pouvait réduire l’érosion cathodique nécessaire au maintien de l’arc en mode thermo-champ (T-F). Les dits précipités ont été produits par implantation ionique par source plasma (IISP). Avec l’aide de techniques de caractérisation telle que la microscopie à fo...

Ultra-high vacuum photoelectron linear accelerator

Science.gov (United States)

Yu, David U.L.; Luo, Yan

2013-07-16

An rf linear accelerator for producing an electron beam. The outer wall of the rf cavity of said linear accelerator being perforated to allow gas inside said rf cavity to flow to a pressure chamber surrounding said rf cavity and having means of ultra high vacuum pumping of the cathode of said rf linear accelerator. Said rf linear accelerator is used to accelerate polarized or unpolarized electrons produced by a photocathode, or to accelerate thermally heated electrons produced by a thermionic cathode, or to accelerate rf heated field emission electrons produced by a field emission cathode.

Study of the heat flux generated by accelerated electrons on the components near the plasma

International Nuclear Information System (INIS)

Laugier, J.

2003-01-01

Experimental data have shown that a heat flux appears on components situated near the wave guide of the lower hybrid antenna of Tore-Supra. This heat flux is due to the energy release during collisions that occur between the component surface and the electrons accelerated by the high frequency field generated by the antenna. Simulations show that the electrons may reach an energy of 2-3 keV and that the heat flux generated in the shield may reach 10 MW/m 2 . In this work a correlation has been established between the local heat flux due to electron impact and the mean electrical field near the antenna: Φ (W/m 2 ) = 4.10 -4 x E -6 (10 5 V/m). It is also shown that the ratio of electrons that reach the shield is roughly not dependent on the value of the mean electrical field. In the hypothesis of a Gaussian distribution of electron initial velocities this ratio is 10%. (A.C.)

Investigation of Three-Dimensional Axisymmetric Unsteady Stagnation-Point Flow and Heat Transfer Impinging on an Accelerated Flat Plate

OpenAIRE

ali shokrgozar abbasi; Asghar Baradaran Rahimi; Hamidreza Mozayeni

2016-01-01

General formulation and solution of Navier-Stokes and energy equations are sought in the study of threedimensional axisymmetric unsteady stagnation-point flow and heat transfer impinging on a flat plate when the plate is moving with variable velocity and acceleration towards the main stream or away from it. As an application, among others, this accelerated plate can be assumed as a solidification front which is being formed with variable velocity. An external fluid, along z - directi...

Evaluation of microwave oven heating for prediction of drug-excipient compatibilities and accelerated stability studies.

Science.gov (United States)

Schou-Pedersen, Anne Marie V; Østergaard, Jesper; Cornett, Claus; Hansen, Steen Honoré

2015-05-15

Microwave ovens have been used extensively in organic synthesis in order to accelerate reaction rates. Here, a set up comprising a microwave oven combined with silicon carbide (SiC) plates for the controlled microwave heating of model formulations has been applied in order to investigate, if a microwave oven is applicable for accelerated drug stability testing. Chemical interactions were investigated in three selected model formulations of drug and excipients regarding the formation of ester and amide reaction products. In the accelerated stability studies, a design of experiments (DoE) approach was applied in order to be able to rank excipients regarding reactivity: Study A: cetirizine with PEG 400, sorbitol, glycerol and propylene glycol. Study B: 6-aminocaproic acid with citrate, acetate, tartrate and gluconate. Study C: atenolol with citric, tartaric, malic, glutaric, and sorbic acid. The model formulations were representative for oral solutions (co-solvents), parenteral solutions (buffer species) and solid dosage forms (organic acids applicable for solubility enhancement). The DoE studies showed overall that the same impurities were generated by microwave oven heating leading to temperatures between 150°C and 180°C as compared to accelerated stability studies performed at 40°C and 80°C using a conventional oven. Ranking of the reactivity of the excipients could be made in the DoE studies performed at 150-180°C, which was representative for the ranking obtained after storage at 40°C and 80°C. It was possible to reduce the time needed for drug-excipient compatibility testing of the three model formulations from weeks to less than an hour in the three case studies. The microwave oven is therefore considered to be an interesting alternative to conventional thermal techniques for the investigation of drug-excipient interactions during preformulation. Copyright © 2015 Elsevier B.V. All rights reserved.

revue bibliographique des représentations analytiques de coefficients d'activité ioniques moyens dans les solutions binaires électrolytiques Bibliographic Review of Analytic Equations of Mean Lonic Activity Coefficients in Electrolytic Binary Solutions

Directory of Open Access Journals (Sweden)

Cruz J. -L.

2006-11-01

Full Text Available Le calcul de certaines propriétés à l'équilibre, de systèmes électrolytiques, nécessite la connaissance des coefficients d'activité en phase liquide des constituants de ces systèmes. L'estimation du coefficient d'activité ionique moyen de l'électrolyte permet, pour des systèmes binaires, de calculer ces coefficients d'activité. Dans cette revue bibliographique sont présentées les principales expressions analytiques, de coefficients d'activité ioniques moyens, fournies par la littérature. II est possible de classer ces expressions en plusieurs grandes catégories en fonction des modèles dont elles dérivent. Des critères de choix, de l'une ou l'autre de ces équations, sont proposés suivant le type de système électrolytique et le domaine de concentration étudiés. Liquid-phase activity coefficients must be known in order to calculate various equilibrium properties of electrolytic systems. For binary systems, these coefficients can be calculated by estimating the mean ionic activity coefficient of the electrolyte. This bibliographic review describes the principal analytic equations for mean ionic activity coefficients found in the literature. These equations can be classified in several major categories according to the theoretical model from which they are derived. Some criteria are proposed for choosing one or another of these equations on the basis of the type of electrolytic system and the concentration range studied.

Grids heat loading of an ion source in two-stage acceleration system

International Nuclear Information System (INIS)

Okumura, Yoshikazu; Ohara, Yoshihiro; Ohga, Tokumichi

1978-05-01

Heat loading of the extraction grids, which is one of the critical problems limiting the beam pulse duration at high power level, has been investigated experimentally, with an ion source in a two-stage acceleration system of four multi-aperture grids. The loading of each grid depends largely on extraction current and grid gap pressures; it decreases with improvement of the beam optics and with decrease of the pressures. In optimum operating modes, its level is typically less than -- 2% of the total beam power or -- 200 W/cm 2 at beam energies of 50 - 70 kV. (auth.)

HEAT TRANSFER METHOD

Science.gov (United States)

Gambill, W.R.; Greene, N.D.

1960-08-30

A method is given for increasing burn-out heat fluxes under nucleate boiling conditions in heat exchanger tubes without incurring an increase in pumping power requirements. This increase is achieved by utilizing a spinning flow having a rotational velocity sufficient to produce a centrifugal acceleration of at least 10,000 g at the tube wall. At this acceleration the heat-transfer rate at burn out is nearly twice the rate which can be achieved in a similar tube utilizing axial flow at the same pumping power. At higher accelerations the improvement over axial flow is greater, and heat fluxes in excess of 50 x 10/sup 6/ Btu/hr/sq ft can be achieved.

Free convective heat transfer with hall effects, heat absorption and chemical reaction over an accelerated moving plate in a rotating system

Energy Technology Data Exchange (ETDEWEB)

Hussain, S.M., E-mail: hussain.modassir@yahoo.com [Department of Mathematics, OP Jindal University, Raigarh 496109 (India); Jain, J., E-mail: jj.28481@gmail.com [Department of Mathematics, OP Jindal University, Raigarh 496109 (India); Seth, G.S., E-mail: gsseth_ism@yahoo.com [Department of Applied Mathematics, Indian School of Mines, Dhanbad 826004 (India); Rashidi, M.M., E-mail: mm_rashidi@yahoo.com [Shanghai Key Lab of Vehicle Aerodynamics and Vehicle Thermal Management System, Tongji University, Shanghai 201804 (China)

2017-01-15

The unsteady MHD free convective heat and mass transfer flow of an electrically conducting, viscous and incompressible fluid over an accelerated moving vertical plate in the presence of heat absorption and chemical reaction with ramped temperature and ramped surface concentration through a porous medium in a rotating system is studied, taking Hall effects into account. The governing equations are solved analytically with the help of Laplace transform technique. The unified closed-form expressions are obtained for fluid velocity, fluid temperature, species concentration, skin friction, Nusselt number and Sherwood numbers. The effects of various parameters on fluid velocity, fluid temperature and species concentration are discussed by graphs whereas numerical values of skin friction, Nusselt and Sherwood numbers are presented in tabular form for different values of pertinent flow parameters. The numerical results are also compared with free convective flow near ramped temperature plate with ramped surface concentration with the corresponding flow near isothermal plate with uniform surface concentration. - Highlights: • Magnetic field, Hall current, rotation and chemical reaction play vital role on flow field. • Hall current tends to accelerate secondary fluid velocity in the boundary layer region. • Rotation tends to retard primary fluid velocity throughout the boundary layer region. • Rotation and chemical reaction tend to enhance primary skin friction. • Solutal buoyancy force and permeability of medium reduce primary skin friction.

Aircraft Thermal Management Using Loop Heat Pipes: Experimental Simulation of High Acceleration Environments Using the Centrifuge Table Test Bed (Postprint)

National Research Council Canada - National Science Library

Fleming, Andrew J; Leland, Quinn H; Yerkes, Kirk L; Elston, Levi J; Thomas, Scott K

2006-01-01

The objective of this paper is to describe the design of an experiment that will examine the effects of elevated acceleration environments on a high-temperature, titanium-water loop heat pipe for actuator cooling...

Evaluation of microwave oven heating for prediction of drug-excipient compatibilities and accelerated stability studies

DEFF Research Database (Denmark)

Schou-Pedersen, Anne Marie V; Østergaard, Jesper; Cornett, Claus

2015-01-01

, if a microwave oven is applicable for accelerated drug stability testing. Chemical interactions were investigated in three selected model formulations of drug and excipients regarding the formation of ester and amide reaction products. The accelerated stability studies performed in the microwave oven using...... a design of experiments (DoE) approach in order to be able to rank excipients regarding reactivity: Study A: cetirizine with PEG 400, sorbitol, glycerol and propylene glycol. Study B: 6-aminocaproic acid with citrate, acetate, tartrate and gluconate. Study C: atenolol with citric, tartaric, malic, glutaric......, and sorbic acid. The model formulations were representative for oral solutions (co-solvents), parenteral solutions (buffer species) and solid dosage forms (organic acids applicable for solubility enhancement). The DoE studies showed overall that the same impurities were generated by microwave oven heating...

Microwave Heating of Synthetic Skin Samples for Potential Treatment of Gout Using the Metal-Assisted and Microwave-Accelerated Decrystallization Technique

OpenAIRE

Toker, Salih; Boone-Kukoyi, Zainab; Thompson, Nishone; Ajifa, Hillary; Clement, Travis; Ozturk, Birol; Aslan, Kadir

2016-01-01

Physical stability of synthetic skin samples during their exposure to microwave heating was investigated to demonstrate the use of the metal-assisted and microwave-accelerated decrystallization (MAMAD) technique for potential biomedical applications. In this regard, optical microscopy and temperature measurements were employed for the qualitative and quantitative assessment of damage to synthetic skin samples during 20 s intermittent microwave heating using a monomode microwave source (at 8 G...

Accelerated testing of solid oxide fuel cell stacks for micro combined heat and power application

DEFF Research Database (Denmark)

Hagen, Anke; Høgh, Jens Valdemar Thorvald; Barfod, Rasmus

2015-01-01

State-of-the-art (SoA) solid oxide fuel cell (SOFC) stacks are tested using profiles relevant for use in micro combined heat and power (CHP) units. Such applications are characterised by dynamic load profiles. In order to shorten the needed testing time and to investigate potential acceleration...... of degradation, the profiles are executed faster than required for real applications. Operation with fast load cycling, both using hydrogen and methane/steam as fuels, does not accelerate degradation compared to constant operation, which demonstrates the maturity of SoA stacks and enables transferring knowledge...... effect for long life-times than regular short time changes of operation. In order to address lifetime testing it is suggested to build a testing program consisting of defined modules that represent different application profiles, such as one module at constant conditions, followed by modules at one set...

Acceleration to High Velocities and Heating by Impact Using Nike KrF laser

Science.gov (United States)

Karasik, Max

2009-11-01

Shock ignition, impact ignition, as well as higher intensity conventional hot spot ignition designs reduce driver energy requirement by pushing the envelope in laser intensity and target implosion velocities. This talk will describe experiments that for the first time reach target velocities in the range of 700 -- 1000 km/s. The highly accelerated planar foils of deuterated polystyrene, some with bromine doping, are made to collide with a witness foil to produce extreme shock pressures and result in heating of matter to thermonuclear temperatures. Target acceleration and collision are diagnosed using large field of view monochromatic x-ray imaging with backlighting as well as bremsstrahlung self-emission. The impact conditions are diagnosed using DD fusion neutron yield, with over 10^6 neutrons produced during the collision. Time-of-flight neutron detectors are used to measure the ion temperature upon impact, which reaches 2 -- 3 keV. The experiments are performed on the Nike facility, reconfigured specifically for high intensity operation. The short wavelength and high illumination uniformity of Nike KrF laser uniquely enable access to this new parameter regime. Intensities of (0.4 -- 1.2) x 10^15 W/cm^2 and pulse durations of 0.4 -- 2 ns were utilized. Modeling of the target acceleration, collision, and neutron production is performed using the FAST3D radiation hydrodynamics code with a non-LTE radiation model. Work is supported by US Department of Energy.

Acceleration of the universe, vacuum metamorphosis, and the large-time asymptotic form of the heat kernel

International Nuclear Information System (INIS)

Parker, Leonard; Vanzella, Daniel A.T.

2004-01-01

We investigate the possibility that the late acceleration observed in the rate of expansion of the Universe is due to vacuum quantum effects arising in curved spacetime. The theoretical basis of the vacuum cold dark matter (VCDM), or vacuum metamorphosis, cosmological model of Parker and Raval is reexamined and improved. We show, by means of a manifestly nonperturbative approach, how the infrared behavior of the propagator (related to the large-time asymptotic form of the heat kernel) of a free scalar field in curved spacetime leads to nonperturbative terms in the effective action similar to those appearing in the earlier version of the VCDM model. The asymptotic form that we adopt for the propagator or heat kernel at large proper time s is motivated by, and consistent with, particular cases where the heat kernel has been calculated exactly, namely in de Sitter spacetime, in the Einstein static universe, and in the linearly expanding spatially flat Friedmann-Robertson-Walker (FRW) universe. This large-s asymptotic form generalizes somewhat the one suggested by the Gaussian approximation and the R-summed form of the propagator that earlier served as a theoretical basis for the VCDM model. The vacuum expectation value for the energy-momentum tensor of the free scalar field, obtained through variation of the effective action, exhibits a resonance effect when the scalar curvature R of the spacetime reaches a particular value related to the mass of the field. Modeling our Universe by an FRW spacetime filled with classical matter and radiation, we show that the back reaction caused by this resonance drives the Universe through a transition to an accelerating expansion phase, very much in the same way as originally proposed by Parker and Raval. Our analysis includes higher derivatives that were neglected in the earlier analysis, and takes into account the possible runaway solutions that can follow from these higher-derivative terms. We find that the runaway solutions do

Acceleration/heating of plasma on auroral field lines: preliminary results from the Viking satellite

International Nuclear Information System (INIS)

Lundin, R.

1988-01-01

In this report, a review of the first results obtained from the particle experiment on board the Viking spacecraft will be given. During the first part of the Viking mission, the orbit was suitable for high-altitude measurements (up to ∼ 13500 km) in the dayside oval and the cusp/cleft region. Thus, some emphasis will be put on processes occurring in the dayside auroral region. On the basis of more than 100 Viking traversals of the cusp and cleft it is suggested that these regions can be identified by some regular characteristics in the particle data. The cusp has a continuous presence of solar wind plasma, affected mainly by convection and containing modest plasma energization. Conversely, the cleft is characterized by extensive plasma energization, and strong field aligned current sheets. Temporal injections of solar wind plasma are frequently observed in the cleft. A distinguishing characteristic of the Viking charged particle experiment is the energy and angular resolution. Thus, the fine-structure of narrow particle beams and conical distributions of both electrons and ions can be determined. This enables very detailed studies of the plasma acceleration processes along auroral field lines. Some examples of accelerated plasma populations and their related energy and angular distribution will be presented. The observations are compared with existing theories of auroral plasma heating and acceleration processes

An experimental study of the air-side particulate fouling in finned-tube heat exchangers of air conditioners through accelerated tests

International Nuclear Information System (INIS)

Ahn, Young Chull; Cho, Jae Min; Lee, Jae Keun; Lee, Hyun Uk; Ahn, Seung Phyo; Youn, Deok Hyun; Kang, Tae Wook; Ock, Ju Jo

2003-01-01

The air-side particulate fouling in the heat exchangers of HVAC applications degrades the performance of cooling capacity, pressure drop across a heat exchanger, and indoor air quality. Indoor and outdoor air contaminants foul heat exchangers. The purpose of this study is to investigate the fouling characteristics trough accelerated tests. The fouling characteristics are analyzed as functions of a dust concentration (1.28 and 3.84 g/m 3 ), a face velocity (0.5, 1.0, and 1.5 m/s), and a surface condition. The cooling capacity in the slitted finned-tube heat exchangers at the face velocity of 1 m/s decreases about 2% and the pressure drop increases up to 57%. The rate of build-up of fouling is observed to be 3 times slower for this three-fold reduction of dust concentration whilst still approaching the same asymptotic level

Correlation to predict heat transfer characteristics of a radially rotating heat pipe at vertical position

Energy Technology Data Exchange (ETDEWEB)

Waowaew, N.; Terdtoon, P.; Kamonpet, P.; Klongpanich, W. [Chiang Mai University (Thailand). Dept. of Mechanical Engineering; Maezawa, S. [Seikei University (Japan). Dept. of Mechanical Engineering

2003-06-01

The heat transfer characteristics of a radially rotating heat pipe (RRHP) depend on a number of parameters. This paper is a study of the effects of these parameters. They are the inner diameter of the tube, aspect ratio, rotational acceleration, working fluid and the dimensionless parameters of heat transfer. RRHPs, made of copper tubes with inner diameters of 11, 26, and 50.4 mm, were used in the experiments. The aspect ratios were 5, 10, 20 and 40 respectively. The selected working fluids were water, ethanol and R123 (CHCI{sub 2}CF{sub 3}) with a filling ratio of 60% of evaporator volume. The experiments were conducted at inclination angles of 0-90{sup o} from horizontal axis and the rotational accelerations were lower, higher and equal to gravitational acceleration. The working temperature was 90{sup o}C. The evaporator section was heated by electric power while heat in the condenser section was removed naturally by air. The evaporator and adiabatic section of the RRHP were well insulated with ceramic fibers. The experimental results showed that the heat flux decreases with an increasing inner diameter, and decreases with an increasing aspect ratio. The heat flux increases with an increasing rotational acceleration and decreases with an increasing liquid density of the working fluid. A correlation to predict the heat transfer rate at vertical position can be established. Further research will investigate a visual study of internal flow pattern and the formulation of a mathematical model. (author)

Utilization of low-energy electron accelerators in Korea

International Nuclear Information System (INIS)

Lee, Byung Cheol

2003-01-01

There are more than 20 electron accelerators in Korea. Most of those are installed in factories for heat-resistant cables, heat-shrinkable cables, radial tires, foams, tube/ films, curing, etc. Four low-energy electron accelerators are in operation for research purposes such as polymer modification, purification of flue gas, waste water treatment, modification of semiconductor characteristics, etc. (author)

Utilization of low-energy electron accelerators in Korea

Energy Technology Data Exchange (ETDEWEB)

Lee, Byung Cheol [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

2003-02-01

There are more than 20 electron accelerators in Korea. Most of those are installed in factories for heat-resistant cables, heat-shrinkable cables, radial tires, foams, tube/ films, curing, etc. Four low-energy electron accelerators are in operation for research purposes such as polymer modification, purification of flue gas, waste water treatment, modification of semiconductor characteristics, etc. (author)

Studies of pellet acceleration with arc discharge heated propellants

International Nuclear Information System (INIS)

Schuresko, D.D.

1985-01-01

An arc discharge has been utilized to heat gaseous propellants in a pneumatic pellet gun. A cylindrical arc chamber is interposed between the propellant inlet valve and the gun breech and fitted with a ceramic insert for generating swirl in the incoming gas stream. The arc is initiated after the propellant valve opens and the breech pressure starts to rise; a typical discharge lasts 300 microseconds with peak currents u to 2 kA at arc voltages ranging from 100 to 400 V. The system is instrumented with piezoelectric pressure transducers at the propellant valve outlet, gun breech, and gun muzzle. The gun has been operated with 4 mm diameter polyurethane foam pellets (density = 0.14 g/cm 3 ), a 40 cm-long barrel, and various gas propellants at pressures exceeding 70 bar. At I/sub arc/ = 1 kA, V/sub arc/ = 200 V, with helium propellant, the arc produces a 2 to 3 fold prompt increase in P/sub breech/ and a delayed increase in P/sub muzzle/; the pellets exit the gun from 0.5 to 1.0 ms earlier than with the gas alone at 40% higher speeds. Comparisons with the so-called ideal gun theory and with full one-dimensional hydrodynamic calculations of the pellet acceleration will be presented

Studies of pellet acceleration with arc discharge heated propellants

International Nuclear Information System (INIS)

Schuresko, D.D.

1986-01-01

An arc discharge has been utilized to heat gaseous propellants in a pneumatic pellet gun. A cylindrical arc chamber is interposed between the propellant inlet valve and the gun breech and fitted with a ceramic insert for generating swirl in the incoming gas stream. The arc is initiated after the propellant valve opens and the breech pressure starts to rise; a typical discharge lasts 300 microseconds with peak currents up to 2 kA at arc voltages ranging from 100-400 V. The system is instrumented with piezoelectric pressure transducers at the propellant valve outlet, gun breech, and gun muzzle. The gun has been operated with 4 mm diameter polyurethane foam pellets (density = 0.14 g/cm 3 ), a 40 cm-long barrel, and various gas propellants at pressures exceeding 70 bar. At I/sub arc/ = 1 kA, V/sub arc/ = 200 V, with helium propellant, the arc produces a 2-3 fold prompt increase in P/sub breech/ and a delayed increase in P/sub muzzle/; the pellets exit the gun from 0.5-1.0 ms earlier than with the gas alone at 40% higher speeds. Comparisons with the so-called ideal gun theory and with full one-dimensional hydrodynamic calculations of the pellet acceleration will be presented

Periodic heat shock accelerated the chondrogenic differentiation of human mesenchymal stem cells in pellet culture.

Directory of Open Access Journals (Sweden)

Jing Chen

Full Text Available Osteoarthritis (OA is one of diseases that seriously affect elderly people's quality of life. Human mesenchymal stem cells (hMSCs offer a potential promise for the joint repair in OA patients. However, chondrogenic differentiation from hMSCs in vitro takes a long time (∼ 6 weeks and differentiated cells are still not as functionally mature as primary isolated chondrocytes, though chemical stimulations and mechanical loading have been intensively studied to enhance the hMSC differentiation. On the other hand, thermal stimulations of hMSC chondrogenesis have not been well explored. In this study, the direct effects of mild heat shock (HS on the differentiation of hMSCs into chondrocytes in 3D pellet culture were investigated. Periodic HS at 41 °C for 1 hr significantly increased sulfated glycosaminoglycan in 3D pellet culture at Day 10 of chondrogenesis. Immunohistochemical and Western Blot analyses revealed an increased expression of collagen type II and aggrecan in heat-shocked pellets than non heat-shocked pellets on Day 17 of chondrogenesis. In addition, HS also upregulated the expression of collagen type I and X as well as heat shock protein 70 on Day 17 and 24 of differentiation. These results demonstrate that HS accelerated the chondrogenic differentiation of hMSCs and induced an early maturation of chondrocytes differentiated from hMSCs. The results of this study will guide the design of future protocols using thermal treatments to facilitate cartilage regeneration with human mesenchymal stem cells.

Performance limiting effects in X-band accelerators

Directory of Open Access Journals (Sweden)

Faya Wang

2011-01-01

Full Text Available Acceleration gradient is a critical parameter for the design of future TeV-scale linear colliders. The major obstacle to higher gradient in room-temperature accelerators is rf breakdown, which is still a very mysterious phenomenon that depends on the geometry and material of the accelerator as well as the input power and operating frequency. Pulsed heating has been associated with breakdown for many years; however, there have been no experiments that clearly separate field and heating effects on the breakdown rate. Recently, such experiments have been performed at SLAC with both standing-wave and traveling-wave structures. These experiments have demonstrated that pulsed heating is limiting the gradient. Nevertheless the X-band structures breakdown studies show damage to the iris surfaces in locations of high electric field rather than of high magnetic field after thousands of breakdowns. It is not yet clear how the relative roles of electric field, magnetic field, and heating factor into the damage caused by rf breakdown. Thus, a dual-moded cavity has been designed to better study the electric field, magnetic field, and pulsed heating effects on breakdown damage.

Heat resistant wire and cable and heat shrinkable tubes

Energy Technology Data Exchange (ETDEWEB)

Ueno, Keiji [Sumitomo Electric Industries Ltd. (Japan)

1994-12-31

Radiation processes have been used in industrial fields (e.g. wire and cable, heat shrinkable tubes) for about 30 years. In Japan, 60 electron beam accelerators were used in R and D, 54 in wire and cable, 24 in tire rubber, 16 in paint curing, 14 in PE foam and 9 accelerators were used in heat shrinkable tubes in 1993. Many properties (e.g. solder resistance, thermal deformation, and solven resistance) of wire and cable are improved by using radiation processes, and many kinds of radiation crosslinked wire and cable are used in the consumer market (TV sets, VTR`s, audio disc players, etc.), automobiles (automobile wire harnesses, fusible link wires, sensor cables etc.), and the industrial market (computer cables, cables for keyboards, coaxial cables, etc.). Another important industrial application of E{beta} radiation process is heat shrinkable tubes. Heat shinkable tubes, heated by a hot gun, shrink 1/2 {approx} 1/3 of their inner diameters. Heat shrinkable tubes are used for covers of distributing line terminals, joint covers of telecommunication lines, protection of fuel pipe lines and so on. In this seminar, actual applications and characteristic properties of radiation crosslinked materials are presented.

Heat resistant wire and cable and heat shrinkable tubes

International Nuclear Information System (INIS)

Keiji Ueno

1994-01-01

Radiation processes have been used in industrial fields (e.g. wire and cable, heat shrinkable tubes) for about 30 years. In Japan, 60 electron beam accelerators were used in R and D, 54 in wire and cable, 24 in tire rubber, 16 in paint curing, 14 in PE foam and 9 accelerators were used in heat shrinkable tubes in 1993. Many properties (e.g. solder resistance, thermal deformation, and solven resistance) of wire and cable are improved by using radiation processes, and many kinds of radiation crosslinked wire and cable are used in the consumer market (TV sets, VTR's, audio disc players, etc.), automobiles (automobile wire harnesses, fusible link wires, sensor cables etc.), and the industrial market (computer cables, cables for keyboards, coaxial cables, etc.). Another important industrial application of Eβ radiation process is heat shrinkable tubes. Heat shinkable tubes, heated by a hot gun, shrink 1/2 ∼ 1/3 of their inner diameters. Heat shrinkable tubes are used for covers of distributing line terminals, joint covers of telecommunication lines, protection of fuel pipe lines and so on. In this seminar, actual applications and characteristic properties of radiation crosslinked materials are presented

Analysis of secondary particle behavior in multiaperture, multigrid accelerator for the ITER neutral beam injector.

Science.gov (United States)

Mizuno, T; Taniguchi, M; Kashiwagi, M; Umeda, N; Tobari, H; Watanabe, K; Dairaku, M; Sakamoto, K; Inoue, T

2010-02-01

Heat load on acceleration grids by secondary particles such as electrons, neutrals, and positive ions, is a key issue for long pulse acceleration of negative ion beams. Complicated behaviors of the secondary particles in multiaperture, multigrid (MAMuG) accelerator have been analyzed using electrostatic accelerator Monte Carlo code. The analytical result is compared to experimental one obtained in a long pulse operation of a MeV accelerator, of which second acceleration grid (A2G) was removed for simplification of structure. The analytical results show that relatively high heat load on the third acceleration grid (A3G) since stripped electrons were deposited mainly on A3G. This heat load on the A3G can be suppressed by installing the A2G. Thus, capability of MAMuG accelerator is demonstrated for suppression of heat load due to secondary particles by the intermediate grids.

Accelerating action of stresses on crystallization kinetics in silicon ion-implanted layers during pulsed heating

International Nuclear Information System (INIS)

Aleksandrov, L.N.

1985-01-01

Numerical simulation of the effect of stressed in ion-implanted layers on kinetics of amorphous phase transformations is performed. The suggested model of accounting stresses including concentration ones is based on the locality of action of interstitial addition atoms and on general structural inhomogeneity of amorphous semiconductor leading to the formation of areas of the facilitated phase transition. Accounting of effect of energy variation of silicon atoms interaction on probability of displacement events and atoms building in lattice points or atomic bonds disintegration allows one to trace the accelerating action of introduced by ion implantation stresses on the kinetics of layer crystallization during pulsed heating

Boundary layer flow of MHD generalized Maxwell fluid over an exponentially accelerated infinite vertical surface with slip and Newtonian heating at the boundary

Directory of Open Access Journals (Sweden)

M.A. Imran

2018-03-01

Full Text Available The aim of this article is to investigate the unsteady natural convection flow of Maxwell fluid with fractional derivative over an exponentially accelerated infinite vertical plate. Moreover, slip condition, radiation, MHD and Newtonian heating effects are also considered. A modern definition of fractional derivative operator recently introduced by Caputo and Fabrizio has been used to formulate the fractional model. Semi analytical solutions of the dimensionless problem are obtained by employing Stehfest’s and Tzou’s algorithms in order to find the inverse Laplace transforms for temperature and velocity fields. Temperature and rate of heat transfer for non-integer and integer order derivatives are computed and reduced to some known solutions from the literature. Finally, in order to get insight of the physical significance of the considered problem regarding velocity and Nusselt number, some graphical illustrations are made using Mathcad software. As a result, in comparison between Maxwell and viscous fluid (fractional and ordinary we found that viscous (fractional and ordinary fluids are swiftest than Maxwell (fractional and ordinary fluids. Keywords: Free convection, Slip, Maxwell fluid, Newtonian heating, Exponentially accelerated plate, Caputo-Fabrizio fractional derivatives, Stehfest’s and Tzou’s algorithms

Calculation of heat fluxes induced by radio frequency heating on the actively cooled protections of ion cyclotron resonant heating (ICRH) and lower hybrid (LH) antennas in Tore Supra

Energy Technology Data Exchange (ETDEWEB)

Ritz, G., E-mail: Guillaume.ritz@gmail.com [CEA, Institut de la Recherche sur la Fusion Magnétique (IRFM), 13108 Saint Paul-lez-Durance (France); Corre, Y., E-mail: Yann.corre@cea.fr [CEA, Institut de la Recherche sur la Fusion Magnétique (IRFM), 13108 Saint Paul-lez-Durance (France); Rault, M.; Missirlian, M. [CEA, Institut de la Recherche sur la Fusion Magnétique (IRFM), 13108 Saint Paul-lez-Durance (France); Portafaix, C. [ITER Organization, Route de Vinon-sur-Verdon, 13115 Saint Paul-lez-Durance (France); Martinez, A.; Ekedahl, A.; Colas, L.; Guilhem, D.; Salami, M.; Loarer, T. [CEA, Institut de la Recherche sur la Fusion Magnétique (IRFM), 13108 Saint Paul-lez-Durance (France)

2013-10-15

Highlights: ► The heat flux generated by radiofrequency (RF) heating was calculated using Tore Supra's heating antennas. ► The highest heat flux value, generated by ions accelerated in RF-rectified sheath potentials, was 5 MW/m{sup 2}. ► The heat flux on the limiters of antennas was in the same order of magnitude as that on the toroidal pumping limiter. -- Abstract: Lower hybrid current drive (LHCD) and ion cyclotron resonance heating (ICRH) are recognized as important auxiliary heating and current drive methods for present and next step fusion devices. However, these radio frequency (RF) systems generate a heat flux up to several MW/m{sup 2} on the RF antennas during plasma operation. This paper focuses on the determination of the heat flux deposited on the lateral protections of the RF antennas in Tore Supra. The heat flux was calculated by finite element method (FEM) using a model of the lateral protection. The FEM calculation was based on surface temperature measurements using infrared cameras monitoring the RF antennas. The heat flux related to the acceleration of electrons in front of the LHCD grills (LHCD active) and to the acceleration of ions in RF-rectified sheath potentials (ICRH active) were calculated. Complementary results on the heat flux related to fast ions (ICRH active with a relatively low magnetic field) are also reported in this paper.

The use of tracers in the study of the ionic permeability of the nerve; Utilisation des indicateurs nucleaires dans l'etude de la permeabilite ionique du nerf

Energy Technology Data Exchange (ETDEWEB)

Guinnebault, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-07-01

The use of the radioactive tracers {sup 24}Na and {sup 42}K, and the electrophysiological fine study carried out on the plant Cephalopods nervous cells have made it possible, during ten years, to study the relationships between the electrical phenomena observed during the propagation of the nervous impulse and the ionic movements which occur at the cell membrane between the intra- and extra-cellular media. In the state of rest, the nerve fibres present a certain permeability towards sodium and potassium, a permeability which allows the renewal, from the extra-cellular medium, of the cations contained in the cytoplasm. At the moment of the passage of the nervous impulse, it is possible to demonstrate a temporary increase in the permeability towards the sodium which causes the entry of Na{sup +} ions into the nerve fibre, whilst, a few milliseconds later, the increase in the potassium permeability causes the departure of an equivalent quantity of K{sup +} ions. A recovery phase follows the passage of the nervous impulse, during which the original ionic conditions are re-established. If the potassium movements can be considered as passive, the expulsion of Na{sup +} requires, on the part of the cell, the use of a part of the metabolic energy. (author) [French] L'utilisation des indicateurs radioactifs {sup 24}Na et {sup 42}K, et l'etude electrophysiologique fine realisee sur des cellules nerveuses geantes de Cephalopodes a permis, depuis une dizaine d'annees, d'etudier les rapports entre les phenomenes electriques observes lors de la propagation de l'influx nerveux et les mouvements ioniques qui s'effectuent au niveau de la membrane cellulaire entre milieux intracellulaire et extracellulaire. A l'etat de repos, les fibres nerveuses possedent pour le sodium et le potassium, une permeabilite qui permet le renouvellement, a partir du milieu extracellulaire des cations contenus dans le cytoplasme. Au moment du passage de l'influx nerveux, on peut mettre en evidence une

Characterization studies of lithium vapour generated in heat pipe oven for the Plasma Wakefield Accelerator Experiment

International Nuclear Information System (INIS)

Mohandas, K.K.; Mahavar, Kanchan; Ajai Kumar; Kumar, Ravi A.V.

2013-01-01

Characterization and optimization studies of lithium vapor by white light as well as UV laser absorption were carried out as part of generation of photo ionized Li plasma for the Plasma Wake Field Acceleration Experiment. Temperature and buffer gas pressure dependency of the neutral density of lithium vapor was studied in detail. The line integrated neutral density of Li(n o L) was found to be of the order of 10 17 -10 18 cm -2 at heat pipe oven temperatures in the range from 600-800℃ which is sufficient to obtain the required 1013-1014 cm -3 plasma densities by photo ionization. (author)

Use of accelerators in the national economy

International Nuclear Information System (INIS)

Skrinskij, A.

1984-01-01

Accelerators generating beams of accelerated particles are the basic component of apparatus used in irradiation technologies. One of the basic trends in irradiation is the improvement of materials, mainly polyethylene and other plastics. Irradiation with accelerated electrons improves their mechanical properties and chemical and heat resistance. Accelerated beams are also used in cement production and in grain disinfestation. The use is being developed of synchrotron radiation for rapid analysis of mineral samples, the manufacture of integrated circuits and for other applications. (Ha)

Comparative study of ageing, heat treatment and accelerated carbonation for stabilization of municipal solid waste incineration bottom ash in view of reducing regulated heavy metal/metalloid leaching.

Science.gov (United States)

Santos, Rafael M; Mertens, Gilles; Salman, Muhammad; Cizer, Özlem; Van Gerven, Tom

2013-10-15

This study compared the performance of four different approaches for stabilization of regulated heavy metal and metalloid leaching from municipal solid waste incineration bottom ash (MSWI-BA): (i) short term (three months) heap ageing, (ii) heat treatment, (iii) accelerated moist carbonation, and (iv) accelerated pressurized slurry carbonation. Two distinct types of MSWI-BA were tested in this study: one originating from a moving-grate furnace incineration operation treating exclusively household refuse (sample B), and another originating from a fluid-bed furnace incineration operation that treats a mixture of household and light industrial wastes (sample F). The most abundant elements in the ashes were Si (20-27 wt.%) and Ca (16-19 wt.%), followed by significant quantities of Fe, Al, Na, S, K, Mg, Ti, and Cl. The main crystalline substances present in the fresh ashes were Quartz, Calcite, Apatite, Anhydrite and Gehlenite, while the amorphous fraction ranged from 56 to 73 wt.%. The leaching values of all samples were compared to the Flemish (NEN 7343) and the Walloon (DIN 38414) regulations from Belgium. Batch leaching of the fresh ashes at natural pH showed that seven elements exceeded at least one regulatory limit (Ba, Cr, Cu, Mo, Pb, Se and Zn), and that both ashes had excess basicity (pH > 12). Accelerated carbonation achieved significant reduction in ash basicity (9.3-9.9); lower than ageing (10.5-12.2) and heat treatment (11.1-12.1). For sample B, there was little distinction between the leaching results of ageing and accelerated carbonation with respect to regulatory limits; however carbonation achieved comparatively lower leaching levels. Heat treatment was especially detrimental to the leaching of Cr. For sample F, ageing was ineffective and heat treatment had marginally better results, while accelerated carbonation delivered the most effective performance, with slurry carbonation meeting all DIN limits. Slurry carbonation was deemed the most

Sporadic plasma heating in the lower chromosphere

Science.gov (United States)

Zaitsev, V. V.

2014-12-01

It is usually assumed that heating of the chromosphere is caused by the precipitation of energetic particles (electrons and protons) accelerated in the solar corona, namely, at flare arc tops. On the other hand, recently obtained observational data show that the chromospheric footpoints of compact magnetic loops are directly heated to ≥106 K, and hot plasma erupted from the footpoints of such loops. The plasma mechanism of the THz emission of flares may also indicate that deep chromospheric layers with densities up to n ≈ 1015 cm-3 can be heated to about 105-106 K. It has been shown that electrons can be accelerated and plasma can be heated in the lower chromosphere when the Rayleigh-Taylor instability develops at magnetic loop chromo-spheric footpoints. This instability results in the penetration of the upper chromospheric plasma into a loop and induces an electric field that effectively accelerates electrons and leads to in situ heating of the chromo-sphere.

Calculations in fundamental physics mechanics and heat

CERN Document Server

Heddle, T

2013-01-01

Calculations in Fundamental Physics, Volume I: Mechanics and Heat focuses on the mechanisms of heat. The manuscript first discusses motion, including parabolic, angular, and rectilinear motions, relative velocity, acceleration of gravity, and non-uniform acceleration. The book then discusses combinations of forces, such as polygons and resolution, friction, center of gravity, shearing force, and bending moment. The text looks at force and acceleration, energy and power, and machines. Considerations include momentum, horizontal or vertical motion, work and energy, pulley systems, gears and chai

RF Pulsed Heating

Energy Technology Data Exchange (ETDEWEB)

Pritzkau, David P.

2002-01-03

RF pulsed heating is a process by which a metal is heated from magnetic fields on its surface due to high-power pulsed RF. When the thermal stresses induced are larger than the elastic limit, microcracks and surface roughening will occur due to cyclic fatigue. Pulsed heating limits the maximum magnetic field on the surface and through it the maximum achievable accelerating gradient in a normal conducting accelerator structure. An experiment using circularly cylindrical cavities operating in the TE{sub 011} mode at a resonant frequency of 11.424 GHz is designed to study pulsed heating on OFE copper, a material commonly used in normal conducting accelerator structures. The high-power pulsed RF is supplied by an X-band klystron capable of outputting 50 MW, 1.5 {micro}s pulses. The test pieces of the cavity are designed to be removable to allow testing of different materials with different surface preparations. A diagnostic tool is developed to measure the temperature rise in the cavity utilizing the dynamic Q change of the resonant mode due to heating. The diagnostic consists of simultaneously exciting a TE{sub 012} mode to steady-state in the cavity at 18 GHz and measuring the change in reflected power as the cavity is heated from high-power pulsed RF. Two experimental runs were completed. One run was executed at a calculated temperature rise of 120 K for 56 x 10{sup 6} pulses. The second run was executed at a calculated temperature rise of 82 K for 86 x 10{sup 6} pulses. Scanning electron microscope pictures show extensive damage occurring in the region of maximum temperature rise on the surface of the test pieces.

Staging of RF-accelerating Units in a MEMS-based Ion Accelerator

Science.gov (United States)

Persaud, A.; Seidl, P. A.; Ji, Q.; Feinberg, E.; Waldron, W. L.; Schenkel, T.; Ardanuc, S.; Vinayakumar, K. B.; Lal, A.

Multiple Electrostatic Quadrupole Array Linear Accelerators (MEQALACs) provide an opportunity to realize compact radio- frequency (RF) accelerator structures that can deliver very high beam currents. MEQALACs have been previously realized with acceleration gap distances and beam aperture sizes of the order of centimeters. Through advances in Micro-Electro-Mechanical Systems (MEMS) fabrication, MEQALACs can now be scaled down to the sub-millimeter regime and batch processed on wafer substrates. In this paper we show first results from using three RF stages in a compact MEMS-based ion accelerator. The results presented show proof-of-concept with accelerator structures formed from printed circuit boards using a 3 × 3 beamlet arrangement and noble gas ions at 10 keV. We present a simple model to describe the measured results. We also discuss some of the scaling behaviour of a compact MEQALAC. The MEMS-based approach enables a low-cost, highly versatile accelerator covering a wide range of currents (10 μA to 100 mA) and beam energies (100 keV to several MeV). Applications include ion-beam analysis, mass spectrometry, materials processing, and at very high beam powers, plasma heating.

Cryogenic Beam Screens for High-Energy Particle Accelerators

CERN Document Server

Baglin, V; Tavian, L; van Weelderen, R

2013-01-01

Applied superconductivity has become a key enabling technology for high-energy particle accelerators, thus making them large helium cryogenic systems operating at very low temperature. The circulation of high-intensity particle beams in these machines generates energy deposition in the first wall through different processes. For thermodynamic efficiency, it is advisable to intercept these beam-induced heat loads, which may be large in comparison with cryostat heat in-leaks, at higher temperature than that of the superconducting magnets of the accelerator, by means of beam screens located in the magnet apertures. Beam screens may also be used as part of the ultra-high vacuum system of the accelerator, by sheltering the gas molecules cryopumped on the beam pipe from impinging radiation and thus avoiding pressure runaway. Space being extremely tight in the magnet apertures, cooling of the long, slender beam screens also raises substantial problems in cryogenic heat transfer and fluid flow. We present sizing rule...

A theoretical investigation of the collective acceleration of cluster ions with accelerated potential waves

International Nuclear Information System (INIS)

Suzuki, Hiroshi; Enjoji, Hiroshi; Kawaguchi, Motoichi; Noritake, Toshiya

1984-01-01

A theoretical treatment of the acceleration of cluster ions for additional heating of fusion plasma using the trapping effect in an accelerated potential wave is described. The conceptual design of the accelerator is the same as that by Enjoji, and the potential wave used is sinusoidal. For simplicity, collisions among cluster ions and the resulting breakups are neglected. The masses of the cluster ions are specified to range from 100 m sub(D) to 1000 m sub(D) (m sub(D): mass of a deuterium atom). Theoretical treatment is carried out only for the injection velocity which coincides with the phase velocity of the applied wave at the entrance of the accelerator. An equation describing the rate for successful acceleration of ions with a certain mass is deduced for the continuous injection of cluster ions. Computation for a typical mass distribution shows that more than 70% of the injected particles are effectively accelerated. (author)

Conduction cooling systems for linear accelerator cavities

Science.gov (United States)

Kephart, Robert

2017-05-02

A conduction cooling system for linear accelerator cavities. The system conducts heat from the cavities to a refrigeration unit using at least one cavity cooler interconnected with a cooling connector. The cavity cooler and cooling connector are both made from solid material having a very high thermal conductivity of approximately 1.times.10.sup.4 W m.sup.-1 K.sup.-1 at temperatures of approximately 4 degrees K. This allows for very simple and effective conduction of waste heat from the linear accelerator cavities to the cavity cooler, along the cooling connector, and thence to the refrigeration unit.

Multi-Mode Cavity Accelerator Structure

Energy Technology Data Exchange (ETDEWEB)

Jiang, Yong [Yale Univ., New Haven, CT (United States); Hirshfield, Jay Leonard [Omega-P R& D, Inc., New Haven, CT (United States)

2016-11-10

This project aimed to develop a prototype for a novel accelerator structure comprising coupled cavities that are tuned to support modes with harmonically-related eigenfrequencies, with the goal of reaching an acceleration gradient >200 MeV/m and a breakdown rate <10^-7/pulse/meter. Phase I involved computations, design, and preliminary engineering of a prototype multi-harmonic cavity accelerator structure; plus tests of a bimodal cavity. A computational procedure was used to design an optimized profile for a bimodal cavity with high shunt impedance and low surface fields to maximize the reduction in temperature rise ΔT. This cavity supports the TM010 mode and its 2nd harmonic TM011 mode. Its fundamental frequency is at 12 GHz, to benchmark against the empirical criteria proposed within the worldwide High Gradient collaboration for X-band copper structures; namely, a surface electric field E_sur^max< 260 MV/m and pulsed surface heating ΔT^max< 56 °K. With optimized geometry, amplitude and relative phase of the two modes, reductions are found in surface pulsed heating, modified Poynting vector, and total RF power—as compared with operation at the same acceleration gradient using only the fundamental mode.

Multi-Mode Cavity Accelerator Structure

International Nuclear Information System (INIS)

Jiang, Yong; Hirshfield, Jay Leonard

2016-01-01

This project aimed to develop a prototype for a novel accelerator structure comprising coupled cavities that are tuned to support modes with harmonically-related eigenfrequencies, with the goal of reaching an acceleration gradient >200 MeV/m and a breakdown rate <10"-"7/pulse/meter. Phase I involved computations, design, and preliminary engineering of a prototype multi-harmonic cavity accelerator structure; plus tests of a bimodal cavity. A computational procedure was used to design an optimized profile for a bimodal cavity with high shunt impedance and low surface fields to maximize the reduction in temperature rise Δ T. This cavity supports the TM010 mode and its 2nd harmonic TM011 mode. Its fundamental frequency is at 12 GHz, to benchmark against the empirical criteria proposed within the worldwide High Gradient collaboration for X-band copper structures; namely, a surface electric field E_s_u_r"m"a"x< 260 MV/m and pulsed surface heating Δ T"m"a"x< 56 °K. With optimized geometry, amplitude and relative phase of the two modes, reductions are found in surface pulsed heating, modified Poynting vector, and total RF power - as compared with operation at the same acceleration gradient using only the fundamental mode.

The effect of broad-band Alfven-cyclotron waves spectra on the preferential heating and differential acceleration of He{sup ++} ions in the solar wind

Energy Technology Data Exchange (ETDEWEB)

Maneva, Y. G. [Department of Physics, Catholic University of America, Washington DC, 20064 (United States) and Heliophysics Science Devision, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Ofman, L. [Department of Physics, Catholic University of America, Washington, DC 20064 (United States) and Heliophysics Science Devision, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Vinas, A. F. [Heliophysics Science Devision, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2013-06-13

In anticipation of results from inner heliospheric missions such as the Solar Orbiter and the Solar Probe we present the results from 1.5D hybrid simulations to study the role of magnetic fluctuations for the heating and differential acceleration of He{sup ++} ions in the solar wind. We consider the effects of nonlinear Alfven-cyclotron waves at different frequency regimes. Monochromatic nonlinear Alfven-alpha-cyclotron waves are known to preferentially heat and accelerate He{sup ++} ions in collisionless low beta plasma. In this study we demonstrate that these effects are preserved when higherfrequency monochromatic and broad-band spectra of Alfven-proton-cyclotron waves are considered. Comparison between several nonlinear monochromatic waves shows that the ion temperatures, anisotropies and relative drift are quantitatively affected by the shift in frequency. Including a broad-band wave-spectrum results in a significant reduction of both the parallel and the perpendicular temperature components for the He{sup ++} ions, whereas the proton heating is barely influenced, with the parallel proton temperature only slightly enhanced. The differential streaming is strongly affected by the available wave power in the resonant daughter ion-acoustic waves. Therefore for the same initial wave energy, the relative drift is significantly reduced in the case of initial wave-spectra in comparison to the simulations with monochromatic waves.

Electron bulk acceleration and thermalization at Earth's quasi-perpendicular bow shock

Science.gov (United States)

Chen, L.-J.; Wang, S.; Wilson, L. B., III; Schwartz, S. J.; Bessho, N.; Moore, T. E.; Gershman, D. J.; Giles, B. L.; Malaspina, D. M.; Wilder, F. D.; Ergun, R. E.; Hesse, M.; Lai, H.; Russell, C. T.; Strangeway, R. J.; Torbert, R. B.; Vinas, A. F.-; Burch, J. L.; Lee, S.; Pollock, C.; Dorelli, J.; Paterson, W. R.; Ahmadi, N.; Goodrich, K. A.; Lavraud, B.; Le Contel, O.; Khotyaintsev, Yu. V.; Lindqvist, P.-A.; Boardsen, S.; Wei, H.; Le, A.; Avanov, L. A.

2018-05-01

Electron heating at Earth's quasiperpendicular bow shock has been surmised to be due to the combined effects of a quasistatic electric potential and scattering through wave-particle interaction. Here we report the observation of electron distribution functions indicating a new electron heating process occurring at the leading edge of the shock front. Incident solar wind electrons are accelerated parallel to the magnetic field toward downstream, reaching an electron-ion relative drift speed exceeding the electron thermal speed. The bulk acceleration is associated with an electric field pulse embedded in a whistler-mode wave. The high electron-ion relative drift is relaxed primarily through a nonlinear current-driven instability. The relaxed distributions contain a beam traveling toward the shock as a remnant of the accelerated electrons. Similar distribution functions prevail throughout the shock transition layer, suggesting that the observed acceleration and thermalization is essential to the cross-shock electron heating.

Solar heating - a major source of renewable energy

International Nuclear Information System (INIS)

Bosselaar, L.

2001-01-01

Actions that can be taken to increase the uptake of technology for solar water heaters and solar buildings are discussed. An overview of existing technology covers solar water heating, solar buildings, space heating, solar cooling, solar drying, solar desalination. Solar water heating, solar buildings and solar crop drying are discussed individually under the sub-headings of (a) the technology; (b) the market; (c) potential; (d) economics and (e) market acceleration strategies. Other subjects discussed are market acceleration, main opportunities, R and D needs and conclusions. The IEA solar heating and solar cooling programme is described

Linear accelerator accelerating module to suppress back-acceleration of field-emitted particles

Science.gov (United States)

Benson, Stephen V.; Marhauser, Frank; Douglas, David R.; Ament, Lucas J. P.

2017-12-05

A method for the suppression of upstream-directed field emission in RF accelerators. The method is not restricted to a certain number of cavity cells, but requires similar operating field levels in all cavities to efficiently annihilate the once accumulated energy. Such a field balance is desirable to minimize dynamic RF losses, but not necessarily achievable in reality depending on individual cavity performance, such as early Q.sub.0-drop or quench field. The method enables a significant energy reduction for upstream-directed electrons within a relatively short distance. As a result of the suppression of upstream-directed field emission, electrons will impact surfaces at rather low energies leading to reduction of dark current and less issues with heating and damage of accelerator components as well as radiation levels including neutron generation and thus radio-activation.

Trends for Electron Beam Accelerator Applications in Industry

Science.gov (United States)

Machi, Sueo

2011-02-01

Electron beam (EB) accelerators are major pieces of industrial equipment used for many commercial radiation processing applications. The industrial use of EB accelerators has a history of more than 50 years and is still growing in terms of both its economic scale and new applications. Major applications involve the modification of polymeric materials to create value-added products, such as heat-resistant wires, heat-shrinkable sheets, automobile tires, foamed plastics, battery separators and hydrogel wound dressing. The surface curing of coatings and printing inks is a growing application for low energy electron accelerators, resulting in an environmentally friendly and an energy-saving process. Recently there has been the acceptance of the use of EB accelerators in lieu of the radioactive isotope cobalt-60 as a source for sterilizing disposable medical products. Environmental protection by the use of EB accelerators is a new and important field of application. A commercial plant for the cleaning flue gases from a coal-burning power plant is in operation in Poland, employing high power EB accelerators. In Korea, a commercial plant uses EB to clean waste water from a dye factory.

Diffusive Shock Acceleration and Turbulent Reconnection

Science.gov (United States)

Garrel, Christian; Vlahos, Loukas; Isliker, Heinz; Pisokas, Theophilos

2018-05-01

Diffusive Shock Acceleration (DSA) cannot efficiently accelerate particles without the presence of self-consistently generated or pre-existing strong turbulence (δB/B ˜ 1) in the vicinity of the shock. The problem we address in this article is: if large amplitude magnetic disturbances are present upstream and downstream of a shock then Turbulent Reconnection (TR) will set in and will participate not only in the elastic scattering of particles but also in their heating and acceleration. We demonstrate that large amplitude magnetic disturbances and Unstable Current Sheets (UCS), spontaneously formed in the strong turbulence in the vicinity of a shock, can accelerate particles as efficiently as DSA in large scale systems and on long time scales. We start our analysis with "elastic" scatterers upstream and downstream and estimate the energy distribution of particles escaping from the shock, recovering the well known results from the DSA theory. Next we analyze the additional interaction of the particles with active scatterers (magnetic disturbances and UCS) upstream and downstream of the shock. We show that the asymptotic energy distribution of the particles accelerated by DSA/TR has very similar characteristics with the one due to DSA alone, but the synergy of DSA with TR is much more efficient: The acceleration time is an order of magnitude shorter and the maximum energy reached two orders of magnitude higher. We claim that DSA is the dominant acceleration mechanism in a short period before TR is established, and then strong turbulence will dominate the heating and acceleration of the particles. In other words, the shock serves as the mechanism to set up a strongly turbulent environment, in which the acceleration mechanism will ultimately be the synergy of DSA and TR.

Diffusion, electrical mobility and ionic interactions in molten Salts; Diffusion, mobilite electrique et interactions ioniques dans les sels fondus

Energy Technology Data Exchange (ETDEWEB)

Lantelme, F. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-05-01

The diffusion and the electrical migration of ions in the molten alkali nitrates LiNO{sub 3}, NaNO{sub 3} and KNO{sub 3} and in their mixtures have been examined using stable or radio-active isotope indicators. This experimental works shows that there are large differences in the diffusion coefficients and the electric mobilities when they are compared using the Nernst-Einstein formula. An interpretive model has been put forward which shows the role played by poly-ionic displacements: in a salt AC the particles moving are not only the free ions A{sup -} and C{sup +} but also the groups [A{sub n}C{sub m}]{sup (m-n)+}... These results confirm the importance of electrostatic attraction and of the polarizability of the ions. This mechanisms, furthermore, explains the inversions of electrical mobilities often observed in liquid ionic media. (author) [French] La diffusion et la migration electrique des ions dans les nitrates alcalins fondus LiNO{sub 3}, NaNO{sub 3} et KNO{sub 3} et dans leurs melanges ont ete examinees a l'aide d'indicateurs isotopiques stables et radioactifs. Cette etude experimentale fait apparaitre des ecarts importants entre les coefficients de diffusion et les mobilites electriques compares au moyen de la formule de Nernst-Einstein. Un modele d'interpretation a pu etre propose mettant en evidence l'existence de deplacements polyioniques: dans un sel AC les particules en mouvement sont non seulement les ions libres A{sup -} et C{sup +} mais aussi des groupes [A{sub n}C{sub m}]{sup (}m{sup -n)+}. Ces resultats precisent l'importance des attractions electro-statiques et de la polarisabilite des ions. D'autre part, ce mecanisme permet de rendre compte des renversements des mobilites electriques souvent observes en milieu ionique liquide.

Diffusion, electrical mobility and ionic interactions in molten Salts; Diffusion, mobilite electrique et interactions ioniques dans les sels fondus

Energy Technology Data Exchange (ETDEWEB)

Lantelme, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-05-01

The diffusion and the electrical migration of ions in the molten alkali nitrates LiNO{sub 3}, NaNO{sub 3} and KNO{sub 3} and in their mixtures have been examined using stable or radio-active isotope indicators. This experimental works shows that there are large differences in the diffusion coefficients and the electric mobilities when they are compared using the Nernst-Einstein formula. An interpretive model has been put forward which shows the role played by poly-ionic displacements: in a salt AC the particles moving are not only the free ions A{sup -} and C{sup +} but also the groups [A{sub n}C{sub m}]{sup (m-n)+}... These results confirm the importance of electrostatic attraction and of the polarizability of the ions. This mechanisms, furthermore, explains the inversions of electrical mobilities often observed in liquid ionic media. (author) [French] La diffusion et la migration electrique des ions dans les nitrates alcalins fondus LiNO{sub 3}, NaNO{sub 3} et KNO{sub 3} et dans leurs melanges ont ete examinees a l'aide d'indicateurs isotopiques stables et radioactifs. Cette etude experimentale fait apparaitre des ecarts importants entre les coefficients de diffusion et les mobilites electriques compares au moyen de la formule de Nernst-Einstein. Un modele d'interpretation a pu etre propose mettant en evidence l'existence de deplacements polyioniques: dans un sel AC les particules en mouvement sont non seulement les ions libres A{sup -} et C{sup +} mais aussi des groupes [A{sub n}C{sub m}]{sup (}m{sup -n)+}. Ces resultats precisent l'importance des attractions electro-statiques et de la polarisabilite des ions. D'autre part, ce mecanisme permet de rendre compte des renversements des mobilites electriques souvent observes en milieu ionique liquide.

Heat-accelerated radioinactivation of attenuated poliovirus

International Nuclear Information System (INIS)

Dugan, V.L.; Trujillo, R.

1975-01-01

Attenuated poliovirus is inactivated in a synergistic manner when exposed simultaneously to heat and ionizing radiation. The synergistic response is observed in both the thermally labile and stable forms of the virus. A three-term kinetic model may be used to describe the inactivation response of the virus in a thermal and/or ionizing radiation environment. (orig.) [de

Characteristics of an electron-beam rocket pellet accelerator

International Nuclear Information System (INIS)

Tsai, C.C.; Foster, C.A.; Schechter, D.E.

1989-01-01

An electron-beam rocket pellet accelerator has been designed, built, assembled, and tested as a proof-of-principle (POP) apparatus. The main goal of accelerators based on this concept is to use intense electron-beam heating and ablation of a hydrogen propellant stick to accelerate deuterium and/or tritium pellets to ultrahigh speeds (10 to 20 km/s) for plasma fueling of next-generation fusion devices such as the International Thermonuclear Engineering Reactor (ITER). The POP apparatus is described and initial results of pellet acceleration experiments are presented. Conceptual ultrahigh-speed pellet accelerators are discussed. 14 refs., 8 figs

Effect of Hall current and chemical reaction on MHD flow along an exponentially accelerated porous flat plate with internal heat absorption/generation

International Nuclear Information System (INIS)

Rath, Pravat Kumar; Dash, G.C.; Patra, Ajit Kumar

2010-01-01

Effect of Hall current on the unsteady free convection flow of an electrically conducting incompressible viscous fluid past an exponentially accelerated vertical porous flat plate with internal heat absorption/generation in the presence of foreign gases (such as H 2 , CO 2 , H 2 O, NH 3 ) and chemical reaction has been investigated. An uniform magnetic field transverse to the plate has been applied. The effects of the Hall current m, the hydromagnetic parameter Mt, the chemical reaction parameter K c the Grashof number for heat transfer G r , the Grashof number for mass transfer G c , the Schmidt number S c , the Prandtl number P r and the transpiration parameter α are discussed in detail. (author)

PONDEROMOTIVE ACCELERATION IN CORONAL LOOPS

International Nuclear Information System (INIS)

Dahlburg, R. B.; Obenschain, K.; Laming, J. M.; Taylor, B. D.

2016-01-01

Ponderomotive acceleration has been asserted to be a cause of the first ionization potential (FIP) effect, the well-known enhancement in abundance by a factor of 3–4 over photospheric values of elements in the solar corona with FIP less than about 10 eV. It is shown here by means of numerical simulations that ponderomotive acceleration occurs in solar coronal loops, with the appropriate magnitude and direction, as a “by-product” of coronal heating. The numerical simulations are performed with the HYPERION code, which solves the fully compressible three-dimensional magnetohydrodynamic equations including nonlinear thermal conduction and optically thin radiation. Numerical simulations of coronal loops with an axial magnetic field from 0.005 to 0.02 T and lengths from 25,000 to 75,000 km are presented. In the simulations the footpoints of the axial loop magnetic field are convected by random, large-scale motions. There is a continuous formation and dissipation of field-aligned current sheets, which act to heat the loop. As a consequence of coronal magnetic reconnection, small-scale, high-speed jets form. The familiar vortex quadrupoles form at reconnection sites. Between the magnetic footpoints and the corona the reconnection flow merges with the boundary flow. It is in this region that the ponderomotive acceleration occurs. Mirroring the character of the coronal reconnection, the ponderomotive acceleration is also found to be intermittent.

PONDEROMOTIVE ACCELERATION IN CORONAL LOOPS

Energy Technology Data Exchange (ETDEWEB)

Dahlburg, R. B.; Obenschain, K. [LCP and FD, Naval Research Laboratory, Washington, DC 20375 (United States); Laming, J. M. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Taylor, B. D. [AFRL Eglin AFB, Pensacola, FL 32542 (United States)

2016-11-10

Ponderomotive acceleration has been asserted to be a cause of the first ionization potential (FIP) effect, the well-known enhancement in abundance by a factor of 3–4 over photospheric values of elements in the solar corona with FIP less than about 10 eV. It is shown here by means of numerical simulations that ponderomotive acceleration occurs in solar coronal loops, with the appropriate magnitude and direction, as a “by-product” of coronal heating. The numerical simulations are performed with the HYPERION code, which solves the fully compressible three-dimensional magnetohydrodynamic equations including nonlinear thermal conduction and optically thin radiation. Numerical simulations of coronal loops with an axial magnetic field from 0.005 to 0.02 T and lengths from 25,000 to 75,000 km are presented. In the simulations the footpoints of the axial loop magnetic field are convected by random, large-scale motions. There is a continuous formation and dissipation of field-aligned current sheets, which act to heat the loop. As a consequence of coronal magnetic reconnection, small-scale, high-speed jets form. The familiar vortex quadrupoles form at reconnection sites. Between the magnetic footpoints and the corona the reconnection flow merges with the boundary flow. It is in this region that the ponderomotive acceleration occurs. Mirroring the character of the coronal reconnection, the ponderomotive acceleration is also found to be intermittent.

A FOCUSED TRANSPORT APPROACH TO THE TIME-DEPENDENT SHOCK ACCELERATION OF SOLAR ENERGETIC PARTICLES AT A FAST TRAVELING SHOCK

International Nuclear Information System (INIS)

Le Roux, J. A.; Webb, G. M.

2012-01-01

Some of the most sophisticated models for solar energetic particle (SEP) acceleration at coronal mass ejection driven shocks are based on standard diffusive shock acceleration theory. However, this theory, which only applies when SEP pitch-angle anisotropies are small, might have difficulty in describing first-order Fermi acceleration or the shock pre-heating and injection of SEPs into first-order Fermi acceleration accurately at lower SEP speeds where SEP pitch-angle anisotropies upstream near the shock can be large. To avoid this problem, we use a time-dependent focused transport model to reinvestigate first-order Fermi acceleration at planar parallel and quasi-parallel spherical traveling shocks between the Sun and Earth with high shock speeds associated with rare extreme gradual SEP events. The focused transport model is also used to investigate and compare three different shock pre-heating mechanisms associated with different aspects of the nonuniform cross-shock solar wind flow, namely, the convergence of the flow (adiabatic compression), the shear tensor of the flow, and the acceleration of the flow, and a fourth shock pre-heating mechanism associated with the cross-shock electric field, to determine which pre-heating mechanism contributes the most to injecting shock pre-heated source particles into the first-order Fermi acceleration process. The effects of variations in traveling shock conditions, such as increasing shock obliquity and shock slowdown, and variations in the SEP source with increasing shock distance from the Sun on the coupled processes of shock pre-heating, injection, and first-order Fermi acceleration are analyzed. Besides the finding that the cross-shock acceleration of the solar wind flow yields the dominant shock pre-heating mechanism at high shock speeds, we find that first-order Fermi acceleration at fast traveling shocks differs in a number of respects from the predictions and assumptions of standard steady-state diffusive shock

GPU accelerated study of heat transfer and fluid flow by lattice Boltzmann method on CUDA

Science.gov (United States)

Ren, Qinlong

Lattice Boltzmann method (LBM) has been developed as a powerful numerical approach to simulate the complex fluid flow and heat transfer phenomena during the past two decades. As a mesoscale method based on the kinetic theory, LBM has several advantages compared with traditional numerical methods such as physical representation of microscopic interactions, dealing with complex geometries and highly parallel nature. Lattice Boltzmann method has been applied to solve various fluid behaviors and heat transfer process like conjugate heat transfer, magnetic and electric field, diffusion and mixing process, chemical reactions, multiphase flow, phase change process, non-isothermal flow in porous medium, microfluidics, fluid-structure interactions in biological system and so on. In addition, as a non-body-conformal grid method, the immersed boundary method (IBM) could be applied to handle the complex or moving geometries in the domain. The immersed boundary method could be coupled with lattice Boltzmann method to study the heat transfer and fluid flow problems. Heat transfer and fluid flow are solved on Euler nodes by LBM while the complex solid geometries are captured by Lagrangian nodes using immersed boundary method. Parallel computing has been a popular topic for many decades to accelerate the computational speed in engineering and scientific fields. Today, almost all the laptop and desktop have central processing units (CPUs) with multiple cores which could be used for parallel computing. However, the cost of CPUs with hundreds of cores is still high which limits its capability of high performance computing on personal computer. Graphic processing units (GPU) is originally used for the computer video cards have been emerged as the most powerful high-performance workstation in recent years. Unlike the CPUs, the cost of GPU with thousands of cores is cheap. For example, the GPU (GeForce GTX TITAN) which is used in the current work has 2688 cores and the price is only 1

Application of electron accelerator for thin film in Indonesia

International Nuclear Information System (INIS)

Danu, Sugiarto; Darsono, Dadang

2004-01-01

Electron accelerator is widely used for the crosslinking of wire and cable insulation, the treatment of heat shrinkable products, precuring of tire components, and the sterilization of medical products. Research and development the use of electron accelerator for thin film in Indonesia covered radiation curing of surface coating, crosslinking of poly (butylenes succinate), crosslinking of wire, cable and heat shrinkable, sterilization of wound dressing, and prevulcanization of tire. In general, comparing with conventional method, electron beam processing have some advantages, such as, less energy consumption, much higher production rate, processing ability at ambient temperature and environmental friendly. Indonesia has a great potential to develop the application of electron accelerator, due to the remarkable growth industrial sector, the abundant of natural resources and the increasing demand of the high quality products. This paper describes the activities concerning with R and D, and application of electron accelerator for processing of thin film. (author)

Acceleration of plasma into vacuum

Energy Technology Data Exchange (ETDEWEB)

Marshall, John [Los Alamos Scientific Laboratory, University of California, Los Alamos, NM (United States)

1958-07-01

The first part of this paper is a discussion of the magnetic acceleration of plasma. The second part contains a description of some experiments which have been performed. In the work reported the intention is: 1. To produce a burst of gas in vacuo; 2. To ionize the gas and heat it to such an extent that it becomes a good electrical conductor. 3. To accelerate the plasma thus produced into vacuum by the use of external time-varying magnetic fields.

Advanced Accelerator Applications University Participation Program

International Nuclear Information System (INIS)

Chen, Y.; Hechanova, A.

2007-01-01

Our research tasks span the range of technology areas for transmutation, gas-cooled reactor technology, and high temperature heat exchangers, including separation of actinides from spent nuclear fuel, methods of fuel fabrication, reactor-accelerator coupled experiments, corrosion of materials exposed to lead-bismuth eutectic, and special nuclear materials protection and accountability. In the six years of this program, we saw the evolution of the national transmutation concepts go from the use of accelerators to fast reactors. We also saw an emphasis on gas-cooled reactors for both high temperature heat and deep burn of nuclear fuel. At the local level, we saw a great birth at UNLV of two new academic programs Fall term of 2004 and the addition of 10 academic and research faculty. The Ph.D. program in Radiochemistry has turned into one of the nation's most visible and successful programs; and, the M.S. program in Materials and Nuclear Engineering initiated Nuclear Engineering academic opportunities which took a long time to come. Our research tasks span the range of technology areas for transmutation, gas-cooled reactor technology, and high temperature heat exchangers, including separation of actinides from spent nuclear fuel, methods of fuel fabrication, reactor-accelerator coupled experiments, corrosion of materials exposed to lead-bismuth eutectic, and special nuclear materials protection and accountability

The ETA-II linear induction accelerator and IMP wiggler: A high-average-power millimeter-wave free-electron-laser for plasma heating

International Nuclear Information System (INIS)

Allen, S.L.; Scharlemann, E.T.

1992-05-01

We have constructed a 140-GHz free-electron laser to generate high-average-power microwaves for heating the MTX tokamak plasma. A 5.5-m steady-state wiggler (intense Microwave Prototype-IMP) has been installed at the end of the upgraded 60-cell ETA-II accelerator, and is configured as an FEL amplifier for the output of a 140-GHz long-pulse gyrotron. Improvements in the ETA-II accelerator include a multicable-feed power distribution network, better magnetic alignment using a stretched-wire alignment technique (SWAT). and a computerized tuning algorithm that directly minimizes the transverse sweep (corkscrew motion) of the electron beam. The upgrades were first tested on the 20-cell, 3-MeV front end of ETA-II and resulted in greatly improved energy flatness and reduced corkscrew motion. The upgrades were then incorporated into the full 60-cell configuration of ETA-II, along with modifications to allow operation in 50-pulse bursts at pulse repetition frequencies up to 5 kHz. The pulse power modifications were developed and tested on the High Average Power Test Stand (HAPTS), and have significantly reduced the voltage and timing jitter of the MAG 1D magnetic pulse compressors. The 2-3 kA. 6-7 MeV beam from ETA-II is transported to the IMP wiggler, which has been reconfigured as a laced wiggler, with both permanent magnets and electromagnets, for high magnetic field operation. Tapering of the wiggler magnetic field is completely computer controlled and can be optimized based on the output power. The microwaves from the FEL are transmitted to the MTX tokamak by a windowless quasi-optical microwave transmission system. Experiments at MTX are focused on studies of electron-cyclotron-resonance heating (ECRH) of the plasma. We summarize here the accelerator and pulse power modifications, and describe the status of ETA-II, IMP, and MTX operations

The ETA-II linear induction accelerator and IMP wiggler: A high-average-power millimeter-wave free-electron laser for plasma heating

International Nuclear Information System (INIS)

Allen, S.L.; Scharlemann, E.T.

1993-01-01

The authors have constructed a 140-GHz free-electron laser to generate high-average-power microwaves for heating the MTX tokamak plasma. A 5.5-m steady-state wiggler (Intense Microwave, Prototype-IMP) has been installed at the end of the upgraded 60-cell ETA-II accelerator, and is configured as an FEL amplifier for the output of a 140-GHz long-pulse gyrotron. Improvements in the ETA-II accelerator include a multicable-feed power distribution network, better magnetic alignment using a stretched-wire alignment technique (SWAT), and a computerized tuning algorithm that directly minimizes the transverse sweep (corkscrew motion) of the electron beam. The upgrades were first tested on the 20-cell, 3-MeV front end of ETA-II and resulted in greatly improved energy flatness and reduced corkscrew motion. The upgrades were then incorporated into the full 60-cell configuration of ETA-II, along with modifications to allow operation in 50-pulse bursts at pulse repetition frequencies up to 5 kHz. The pulse power modifications were developed and tested on the High Average Power Test Stand (HAPTS), and have significantly reduced the voltage and timing jitter of the MAG 1D magnetic pulse compressors. The 2-3 kA, 6-7 MeV beam from ETA-II is transported to the IMP wiggler, which has been reconfigured as a laced wiggler, with both permanent magnets and electromagnets, for high magnetic field operation. Tapering of the wiggler magnetic field is completely computer controlled and can be optimized based on the output power. The microwaves from the FEL are transmitted to the MTX tokamak by a windowless quasi-optical microwave transmission system. Experiments at MTX are focused on studies of electron-cyclotron-resonance heating (ECRH) of the plasma. The authors summarize here the accelerator and pulse power modifications, and describe the status of ETA-II, IMP, and MTX operations

Investigation of pellet acceleration by an arc heated gas gun. An interim report of the investigations carried out to 31 August 1985

International Nuclear Information System (INIS)

Andersen, S.A.; Bundgaard, J.; Jensen, V.O.; Nordskov, A.; Sass, B.; Soerensen, H.; Weisberg, K.V.

1985-12-01

Deep penetration of pellets into the JET plasma may prove to be a useful tool for density and profile control. In JET deep penetration will require pellet velocities and sizes above those obtained so far. An experimental setup designed for a study of acceleration of 3 mm diameter pellets by an arc heated gas gun is described. The aim of the work is to obtain pellet velocities well above 2 km/s. To obtain this aim will require a much more powerful power unit than the one that was available for the present work. Only a few results, obtained mostly during testing of the various parts of the setup, are presented. Although the obtained velocities are low (∝1500 m/s) the results are encouraging because they demonstrate that pellets can stand a high acceleration pressure without disintegrating. With a suitable power supply which can maintain this high acceleration pressure as the pellet moves all the way through the barrel, velocities above 2 km/s would certainly be expected. (orig.)

DNS of heat transfer in transitional, accelerated boundary layer flow over a flat plate affected by free-stream fluctuations

International Nuclear Information System (INIS)

Wissink, Jan G.; Rodi, Wolfgang

2009-01-01

Direct numerical simulations (DNS) of flow over and heat transfer from a flat plate affected by free-stream fluctuations were performed. A contoured upper wall was employed to generate a favourable streamwise pressure gradient along a large portion of the flat plate. The free-stream fluctuations originated from a separate LES of isotropic turbulence in a box. In the laminar portions of the accelerating boundary layer flow the formation of streaks was observed to induce an increase in heat transfer by the exchange of hot fluid near the surface of the plate and cold fluid from the free-stream. In the regions where the streamwise pressure gradient was only mildly favourable, intermittent turbulent spots were detected which relaminarised downstream as the streamwise pressure gradient became stronger. The relaminarisation of the turbulent spots was reflected by a slight decrease in the friction coefficient, which converged to its laminar value in the region where the streamwise pressure gradient was strongest.

Infinite stochastic acceleration of charged particles from non-relativistic initial energies

International Nuclear Information System (INIS)

Buts, V.A.; Manujlenko, O.V.; Turkin, Yu.A.

1997-01-01

Stochastic charged particle acceleration by electro-magnetic field due to overlapping of non-linear cyclotron resonances is considered. It was shown that non-relativistic charged particles are involved in infinitive stochastic acceleration regime. This effect can be used for stochastic acceleration or for plasma heating by regular electro-magnetic fields

Thermal management of microelectronics with electrostatic fluid accelerators

International Nuclear Information System (INIS)

Wang, Hsiu-Che; Jewell-Larsen, Nels E.; Mamishev, Alexander V.

2013-01-01

Optimal thermal management is critical in modern consumer electronics. Typically, a thermal management scheme for an electronic system involves several physical principles. In many cases, it is highly desirable to enhance heat transfer at the solid-air interface while maintaining small size of the thermal management solution. The enhancement of heat transfer at the solid-air interface can be achieved by several physical principles. One principle that is getting increased attention of thermal management design engineers is electrostatic fluid acceleration. This paper discusses recent breakthroughs in state-of-the-art of electrostatic fluid accelerators (EFAs). The paper compares and contrasts EFAs’ design and performance metrics to those of other airside cooling technologies used in small form factor applications. Since the energy efficiency, flow rate, and acoustic emissions are highly influenced by the scale of the airside cooling devices, the paper also presents the analysis of fundamental effect of scaling laws on heat transfer performance. The presented review and analysis helps drawing conclusions regarding achievable comparative performance and practicality of using different design approaches and physical principles for different applications. -- Highlights: ► Discuss breakthrough in state-of-the-art of electrostatic fluid accelerators (EFA). ► Compare EFAs' performance metrics to those of other airside cooling technologies. ► Show analysis of fundamental effect of scaling laws on heat transfer performance

Application of powerful quasi-steady-state plasma accelerators for simulation of ITER transient heat loads on divertor surfaces

Energy Technology Data Exchange (ETDEWEB)

Tereshin, V I [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Bandura, A N [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Byrka, O V [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Chebotarev, V V [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Garkusha, I E [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Landman, I [Forschungszentrum Karlsruhe, IHM, Karlsruhe 76021 (Germany); Makhlaj, V A [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Neklyudov, I M [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Solyakov, D G [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Tsarenko, A V [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine)

2007-05-15

The paper presents the investigations of high power plasma interaction with material surfaces under conditions simulating the ITER disruptions and type I ELMs. Different materials were exposed to plasma with repetitive pulses of 250 {mu}s duration, the ion energy of up to 0.6 keV, and the heat loads varying in the 0.5-25 MJ m{sup -2} range. The plasma energy transfer to the material surface versus impact load has been analysed. The fraction of plasma energy that is absorbed by the target surface is rapidly decreased with the achievement of the evaporation onset for exposed targets. The distributions of evaporated material in front of the target surface and the thickness of the shielding layer are found to be strongly dependent on the target atomic mass. The surface analysis of tungsten targets exposed to quasi-steady-state plasma accelerators plasma streams is presented together with measurements of the melting onset load and evaporation threshold, and also of erosion patterns with increasing heat load and the number of plasma pulses.

Dehydration accelerates reductions in cerebral blood flow during prolonged exercise in the heat without compromising brain metabolism.

Science.gov (United States)

Trangmar, Steven J; Chiesa, Scott T; Llodio, Iñaki; Garcia, Benjamin; Kalsi, Kameljit K; Secher, Niels H; González-Alonso, José

2015-11-01

Dehydration hastens the decline in cerebral blood flow (CBF) during incremental exercise, whereas the cerebral metabolic rate for O2 (CMRO2 ) is preserved. It remains unknown whether CMRO2 is also maintained during prolonged exercise in the heat and whether an eventual decline in CBF is coupled to fatigue. Two studies were undertaken. In study 1, 10 male cyclists cycled in the heat for ∼2 h with (control) and without fluid replacement (dehydration) while internal and external carotid artery blood flow and core and blood temperature were obtained. Arterial and internal jugular venous blood samples were assessed with dehydration to evaluate CMRO2 . In study 2, in 8 male subjects, middle cerebral artery blood velocity was measured during prolonged exercise to exhaustion in both dehydrated and euhydrated states. After a rise at the onset of exercise, internal carotid artery flow declined to baseline with progressive dehydration (P dehydration accelerates the decline in CBF without affecting CMRO2 and also restricts extracranial perfusion. Thus, fatigue is related to a reduction in CBF and extracranial perfusion rather than CMRO2 . Copyright © 2015 the American Physiological Society.

Rippled plasma wall accelerating structures

International Nuclear Information System (INIS)

Cavenago, M.

1992-01-01

A concept to form a hot, pulsed, inhomogeneous plasma and to use it as a linac structure is presented. The plasma spatial distribution is controlled by an external magnetic field and by the location of thermionic emitters; microwave ECR heating at frequency ω 1 favours plasma build up and reduces plasma resistivity. A shorter microwave pulse with frequency ω 2 ≠ ω 1 excites a longitudinal mode. An expression for the maximum attainable accelerating field is found. A linearized theory of accelerating modes is given. (Author) 6 refs., 3 figs

Impact of wave phase jumps on stochastic heating

International Nuclear Information System (INIS)

Zasenko, V.I.; Zagorodny, A.G.; Cherniak, O.M.

2016-01-01

Interaction of charged particles with fields of random waves brings about known effects of stochastic acceleration and heating. Jumps of wave phases can increase the intensity of these processes substantially. Numerical simulation of particle heating and acceleration by waves with regular phases, waves with jumping phase and stochastic electric field impulses is performed. Comparison of the results shows that to some extent an impact of phase jumps is similar to the action of separate field impulses. Jumps of phase not only increase the intensity of resonant particle heating but involves in this process non-resonant particles from a wide range of initial velocities

Acceleration of calculation of nuclear heating distributions in ITER toroidal field coils using hybrid Monte Carlo/deterministic techniques

International Nuclear Information System (INIS)

Ibrahim, Ahmad M.; Polunovskiy, Eduard; Loughlin, Michael J.; Grove, Robert E.; Sawan, Mohamed E.

2016-01-01

Highlights: • Assess the detailed distribution of the nuclear heating among the components of the ITER toroidal field coils. • Utilize the FW-CADIS method to dramatically accelerate the calculation of detailed nuclear analysis. • Compare the efficiency and reliability of the FW-CADIS method and the MCNP weight window generator. - Abstract: Because the superconductivity of the ITER toroidal field coils (TFC) must be protected against local overheating, detailed spatial distribution of the TFC nuclear heating is needed to assess the acceptability of the designs of the blanket, vacuum vessel (VV), and VV thermal shield. Accurate Monte Carlo calculations of the distributions of the TFC nuclear heating are challenged by the small volumes of the tally segmentations and by the thick layers of shielding provided by the blanket and VV. To speed up the MCNP calculation of the nuclear heating distribution in different segments of the coil casing, ground insulation, and winding packs of the ITER TFC, the ITER Organization (IO) used the MCNP weight window generator (WWG). The maximum relative uncertainty of the tallies in this calculation was 82.7%. In this work, this MCNP calculation was repeated using variance reduction parameters generated by the Oak Ridge National Laboratory AutomateD VAriaNce reducTion Generator (ADVANTG) code and both MCNP calculations were compared in terms of computational efficiency and reliability. Even though the ADVANTG MCNP calculation used less than one-sixth of the computational resources of the IO calculation, the relative uncertainties of all the tallies in the ADVANTG MCNP calculation were less than 6.1%. The nuclear heating results of the two calculations were significantly different by factors between 1.5 and 2.3 in some of the segments of the furthest winding pack turn from the plasma neutron source. Even though the nuclear heating in this turn may not affect the ITER design because it is much smaller than the nuclear heating in the

Acceleration of calculation of nuclear heating distributions in ITER toroidal field coils using hybrid Monte Carlo/deterministic techniques

Energy Technology Data Exchange (ETDEWEB)

Ibrahim, Ahmad M., E-mail: ibrahimam@ornl.gov [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Polunovskiy, Eduard; Loughlin, Michael J. [ITER Organization, Route de Vinon Sur Verdon, 13067 St. Paul Lez Durance (France); Grove, Robert E. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Sawan, Mohamed E. [University of Wisconsin-Madison, 1500 Engineering Dr., Madison, WI 53706 (United States)

2016-11-01

Highlights: • Assess the detailed distribution of the nuclear heating among the components of the ITER toroidal field coils. • Utilize the FW-CADIS method to dramatically accelerate the calculation of detailed nuclear analysis. • Compare the efficiency and reliability of the FW-CADIS method and the MCNP weight window generator. - Abstract: Because the superconductivity of the ITER toroidal field coils (TFC) must be protected against local overheating, detailed spatial distribution of the TFC nuclear heating is needed to assess the acceptability of the designs of the blanket, vacuum vessel (VV), and VV thermal shield. Accurate Monte Carlo calculations of the distributions of the TFC nuclear heating are challenged by the small volumes of the tally segmentations and by the thick layers of shielding provided by the blanket and VV. To speed up the MCNP calculation of the nuclear heating distribution in different segments of the coil casing, ground insulation, and winding packs of the ITER TFC, the ITER Organization (IO) used the MCNP weight window generator (WWG). The maximum relative uncertainty of the tallies in this calculation was 82.7%. In this work, this MCNP calculation was repeated using variance reduction parameters generated by the Oak Ridge National Laboratory AutomateD VAriaNce reducTion Generator (ADVANTG) code and both MCNP calculations were compared in terms of computational efficiency and reliability. Even though the ADVANTG MCNP calculation used less than one-sixth of the computational resources of the IO calculation, the relative uncertainties of all the tallies in the ADVANTG MCNP calculation were less than 6.1%. The nuclear heating results of the two calculations were significantly different by factors between 1.5 and 2.3 in some of the segments of the furthest winding pack turn from the plasma neutron source. Even though the nuclear heating in this turn may not affect the ITER design because it is much smaller than the nuclear heating in the

Acceleration of electrons and supplementary ionization during parametrical plasma heating

International Nuclear Information System (INIS)

Grach, S.M.; Mityakov, N.A.; Trakhtengerts, V.Yu.; AN SSSR, Gor'kij. Inst. Prikladnoj Fiziki)

1986-01-01

Acceleration of electrons by plasma waves in partially ionized plasma is considered with provision for the effects of turbulent scattering and formation of secondary electrons, which are produced in the process of electron shock ionization. It is shown that the avalanche density growth of electrons accelerated up to 1-2 ionization potential (instability) takes place beginning from some critical density of plasma waves. Density of fast electrons is found out along with plasma wave energy density at the stage of instability saturation. Additional concentration of a background plasma, which manifests itself due to ionization, is evaluated

Long-pulse beam acceleration of MeV-class H(-) ion beams for ITER NB accelerator.

Science.gov (United States)

Umeda, N; Kashiwagi, M; Taniguchi, M; Tobari, H; Watanabe, K; Dairaku, M; Yamanaka, H; Inoue, T; Kojima, A; Hanada, M

2014-02-01

In order to realize neutral beam systems in International Thermonuclear Experimental Reactor whose target is to produce a 1 MeV, 200 A/m(2) during 3600 s D(-) ion beam, the electrostatic five-stages negative ion accelerator so-called "MeV accelerator" has been developed at Japan Atomic Energy Agency. To extend pulse length, heat load of the acceleration grids was reduced by controlling the ion beam trajectory. Namely, the beam deflection due to the residual magnetic field of filter magnet was suppressed with the newly developed extractor with a 0.5 mm off-set aperture displacement. The new extractor improved the deflection angle from 6 mrad to 1 mrad, resulting in the reduction of direct interception of negative ions from 23% to 15% of the total acceleration power, respectively. As a result, the pulse length of 130 A/m(2), 881 keV H(-) ion beam has been successfully extended from a previous value of 0.4 s to 8.7 s. This is the first long pulse negative ion beam acceleration over 100 MW/m(2).

Target/Blanket Design for the Accelerator Production of Tritium Plant

International Nuclear Information System (INIS)

Cappiello, M. W.

1997-01-01

The Accelerator Production of Tritium Target/Blanket (T/B) system is comprised of the T/B assembly and the attendant heat removal systems. The T/B assembly produces tritium using a high energy proton beam, and a spallation neutron source. The supporting heat removal systems safely remove the heat deposited by the proton beam during both normal and off-normal conditions. All systems reside within the T/B building, which is located at the end of a linear accelerator. Protons are accelerated to an energy of 1700 MeV at a current of 100 mA and are directed onto the T/B assembly. The protons interact with tungsten and lead nuclei to produce neutrons through the process of nuclear spallation. Neutron capture in 3 He gas produces tritium which is removed on a continual basis in an adjacent Tritium Separation Facility (TSF). The T/B assembly is modular to allow for replacement of spent components and minimization of waste. Systems and components are designed with safety as a primary consideration to minimize risk to the workers and the public

Can Substorm Particle Acceleration Be Applied to Solar Flares?

Energy Technology Data Exchange (ETDEWEB)

Birn, J. [Space Science Institute, Boulder, CO 80301 (United States); Battaglia, M. [Institute of 4D Technologies, School of Engineering, University of Applied Sciences and Arts Northwestern Switzerland, CH-5210 Windisch (Switzerland); Fletcher, L. [University of Glasgow, Scotland (United Kingdom); Hesse, M. [Birkeland Centre for Space Science, Department of Physics and Technology, University of Bergen, NO-5007 Bergen (Norway); Neukirch, T., E-mail: jbirn@lanl.gov [University of St. Andrews, Scotland (United Kingdom)

2017-10-20

Using test particle studies in the electromagnetic fields of three-dimensional magnetohydrodynamic (MHD) simulations of magnetic reconnection, we study the energization of charged particles in the context of the standard two-ribbon flare picture in analogy to the standard magnetospheric substorm paradigm. In particular, we investigate the effects of the collapsing field (“collapsing magnetic trap”) below a reconnection site, which has been demonstrated to be the major acceleration mechanism that causes energetic particle acceleration and injections observed in Earth’s magnetotail associated with substorms and other impulsive events. We contrast an initially force-free, high-shear field (low beta) with low and moderate shear, finite-pressure (high-beta) arcade structures, where beta represents the ratio between gas (plasma) and magnetic pressure. We demonstrate that the energization affects large numbers of particles, but the acceleration is modest in the presence of a significant shear field. Without incorporating loss mechanisms, the effect on particles at different energies is similar, akin to adiabatic heating, and thus is not a likely mechanism to generate a power-law tail onto a (heated or not heated) Maxwellian velocity distribution.

ETA-II accelerator upgrades

International Nuclear Information System (INIS)

Nilson, D.G.; Deadrick, F.J.; Hibbs, S.M.; Sampayan, S.E.; Petersen, D.E.

1991-09-01

We discuss recent improvements to the ETA-II linear induction electron accelerator. The accelerator's cells have been carefully reconditioned to raise the maximum accelerating gap voltage from approximately 100 kV to 125 kV. Insulators of Rexolite plastic in a new ''zero-gap'' arrangement replaced the alumina originals after several alternative materials were investigated. A new multi-cable current feed system will be used to eliminate pulse reflection interactions encountered in earlier experiments. Improved alignment fixtures have been installed to help minimize beam perturbation due to poorly aligned intercell magnets between 10-cell groups. A stretched wire alignment technique (SWAT) has been utilized to enhance overall magnetic alignment, and to characterize irreducible alignment errors. These changes are in conjunction with an expansion of the accelerator from a 20-cell to a 60-cell configuration. When completed, the upgraded accelerator is expected to deliver 2.5 kA of electron beam current at 7.5 MeV in bursts of up to fifty 70-ns pulses at a 5-kHz repetition rate. A 5.5-meter-long wiggler will convert the energy into 3-GW microwave pulses at 140 GHz for plasma heating experiments in the Microwave Tokamak Experiment (MTX)

Unravelling convective heat transfer in the Rotated Arc Mixer

NARCIS (Netherlands)

Speetjens, M.F.M.; Baskan, O.; Metcalfe, G.; Clercx, H.J.H.

2014-01-01

Thermal homogenization is essentially a transient problem and convective heat transfer by (chaotic) advection is known to accelerate this process. Convective heat transfer traditionally is examined in terms of heat-transfer coefficients at domain walls and characterised by Nusselt relations.

A COLD FLARE WITH DELAYED HEATING

International Nuclear Information System (INIS)

Fleishman, Gregory D.; Pal'shin, Valentin D.; Lysenko, Alexandra L.; Meshalkina, Natalia; Kashapova, Larisa K.; Altyntsev, Alexander T.

2016-01-01

Recently, a number of peculiar flares have been reported that demonstrate significant nonthermal particle signatures with low, if any, thermal emission, which implies a close association of the observed emission with the primary energy release/electron acceleration region. This paper presents a flare that appears “cold” at the impulsive phase, while displaying delayed heating later on. Using hard X-ray data from Konus- Wind , microwave observations by SSRT, RSTN, NoRH, and NoRP, context observations, and three-dimensional modeling, we study the energy release, particle acceleration, and transport, and the relationships between the nonthermal and thermal signatures. The flaring process is found to involve the interaction between a small loop and a big loop with the accelerated particles divided roughly equally between them. Precipitation of the electrons from the small loop produced only a weak thermal response because the loop volume was small, while the electrons trapped in the big loop lost most of their energy in the coronal part of the loop, which resulted in coronal plasma heating but no or only weak chromospheric evaporation, and thus unusually weak soft X-ray emission. The energy losses of the fast electrons in the big tenuous loop were slow, which resulted in the observed delay of the plasma heating. We determined that the impulsively accelerated electron population had a beamed angular distribution in the direction of the electric force along the magnetic field of the small loop. The accelerated particle transport in the big loop was primarily mediated by turbulent waves, which is similar to other reported cold flares.

BC SEA Solar Hot Water Acceleration project

Energy Technology Data Exchange (ETDEWEB)

Harris, N.C. [BC Sustainable Energy Association, Victoria, BC (Canada)

2005-07-01

Although solar hot water heating is an environmentally responsible technology that reduces fossil fuel consumption and helps mitigate global climate change, there are many barriers to its widespread use. Each year, domestic water heating contributes nearly 6 million tonnes of carbon dioxide towards Canada's greenhouse gas emissions. The installation of solar water heaters can eliminate up to 2 tonnes of carbon dioxide emissions per household. The BC SEA Solar Hot Water Acceleration project was launched in an effort to demonstrate that the technology has the potential to be widely used in homes and businesses across British Columbia. One of the main barriers to the widespread use of solar hot water heating is the initial cost of the system. Lack of public awareness and understanding of the technology are other barriers. However, other jurisdictions around the world have demonstrated that the use of renewables are the product of conscious policy decisions, including low-cost financing and other subsidies that have created demand for these technologies. To this end, the BC SEA Solar Hot Water Acceleration project will test the potential for the rapid acceleration of solar water heating in pilot communities where barriers are removed. The objective of the project is to install 100 solar water systems in homes and 25 in businesses and institutions in communities in British Columbia by July 2007. The project will explore the financial barriers to the installation of solar hot water systems and produce an action plan to reduce these barriers. In addition to leading by example, the project will help the solar energy marketplace, mitigate climate change and improve energy efficiency.

The lumped heat capacity method applied to target heating

OpenAIRE

Rickards, J.

2013-01-01

The temperature of metal samples was measured while they were bombarded by the beam from the a particle accelerator. The evolution of the temperature with time can be explained using the lumped heat capacity method of heat transfer. A strong dependence on the type of mounting was found. Se midió la temperatura de muestras metálicas al ser bombardeadas por el haz de iones del Acelerador Pelletron del Instituto de Física. La evolución de la temperatura con el tiempo se puede explicar usando ...

Accelerator and Ion Beam Tradeoffs for Studies of Warm Dense Matter

CERN Document Server

Barnard, John J; Callahan, Debra; Davidson, Ronald C; Friedman, Alex; Grant-Logan, B; Grisham, Larry; Lee, Edward; Lee, Richard; Olson, Craig; Rose, David; Santhanam, Parthiban; Sessler, Andrew M; Staples, John W; Tabak, Max; Welch, Dale; Wurtele, Jonathan; Yu, Simon

2005-01-01

One approach to heat a target to "Warm Dense Matter" conditions (similar, for example, to the interiors of giant planets or certain stages in Inertial Confinement Fusion targets), is to use intense ion beams as the heating source. By consideration of ion beam phase space constraints, both at the injector, and at the final focus, and consideration of simple equations of state, approximate conditions at a target foil may be calculated. Thus target temperature and pressure may be calculated as a function of ion mass, ion energy, pulse duration, velocity tilt, and other accelerator parameters. We examine the variation in target performance as a function of various beam and accelerator parameters, in the context of several different accelerator concepts, recently proposed for WDM studies.

Accelerated SDS depletion from proteins by transmembrane electrophoresis: Impacts of Joule heating.

Science.gov (United States)

Unterlander, Nicole; Doucette, Alan Austin

2018-02-08

SDS plays a key role in proteomics workflows, including protein extraction, solubilization and mass-based separations (e.g. SDS-PAGE, GELFrEE). However, SDS interferes with mass spectrometry and so it must be removed prior to analysis. We recently introduced an electrophoretic platform, termed transmembrane electrophoresis (TME), enabling extensive depletion of SDS from proteins in solution with exceptional protein yields. However, our prior TME runs required 1 h to complete, being limited by Joule heating which causes protein aggregation at higher operating currents. Here, we demonstrate effective strategies to maintain lower TME sample temperatures, permitting accelerated SDS depletion. Among these strategies, the use of a magnetic stir bar to continuously agitate a model protein system (BSA) allows SDS to be depleted below 100 ppm (>98% removal) within 10 min of TME operations, while maintaining exceptional protein recovery (>95%). Moreover, these modifications allow TME to operate without any user intervention, improving throughput and robustness of the approach. Through fits of our time-course SDS depletion curves to an exponential model, we calculate SDS depletion half-lives as low as 1.2 min. This promising electrophoretic platform should provide proteomics researchers with an effective purification strategy to enable MS characterization of SDS-containing proteins. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of some commercial grade polymers as possible dosimeters for technological irradiations in electron accelerators

CERN Document Server

Bryl-Sandelewska, T

2002-01-01

Dosimetric properties of two kinds of clear polymethylmethacrylate (PMMA)and one kind of polystyrene (PS) sheets in technological accelerator irradiations, are presented. Absorbance of the sheets and its dependence on the dose have been measured at a suitable wavelength using a UV/VIS spectrophotometer. Both kind PMMA can be used for technological dose measurements but each of them in the different range of the doses (approx 3 to approx 30 kGy and approx 30 to above 200 kGy). Heating the samples after irradiation accelerates the stabilization of the absorbance, which change slowly during the storage of the samples if not heated.Absorbance of clear PS sheets decreases very much during the storage after irradiation, and heating of the samples does not accelerate the stabilization of the value. It can be said that the Ps investigated is not suitable for technological dose measurements in accelerator i radiations.

Evaluation of some commercial grade polymers as possible dosimeters for technological irradiations in electron accelerators

International Nuclear Information System (INIS)

Bryl-Sandelewska, T.; Panta, P.P.

2002-01-01

Dosimetric properties of two kinds of clear polymethylmethacrylate (PMMA)and one kind of polystyrene (PS) sheets in technological accelerator irradiations, are presented. Absorbance of the sheets and its dependence on the dose have been measured at a suitable wavelength using a UV/VIS spectrophotometer. Both kind PMMA can be used for technological dose measurements but each of them in the different range of the doses (∼ 3 to ∼30 kGy and ∼ 30 to above 200 kGy). Heating the samples after irradiation accelerates the stabilization of the absorbance, which change slowly during the storage of the samples if not heated.Absorbance of clear PS sheets decreases very much during the storage after irradiation, and heating of the samples does not accelerate the stabilization of the value. It can be said that the Ps investigated is not suitable for technological dose measurements in accelerator i radiations. (author)

Thermo-mechanical analysis of an acceleration grid for the international thermonuclear experimental reactor-neutral beam injection system

International Nuclear Information System (INIS)

Fujiwara, Yukio; Hanada, Masaya; Okumura, Yoshikazu; Suzuki, Satoshi; Watanabe, Kazuhiro

2001-01-01

In the engineering design of a negative-ion beam source for a high-power neutral beam injection (NBI) system, one of the most important issues is thermo-mechanical design of acceleration grids for producing several tens of MW ion beams. An acceleration grid for the international thermonuclear experimental reactor-neutral beam injection (ITER-NBI) system will be subjected to the heat loading as high as 1.5 MW. In the present paper, thermo-mechanical characteristics of the acceleration grid for the ITER-NBI system were analyzed. Numerical simulation indicated that maximum aperture-axis displacement of the acceleration grid due to thermal expansion would be about 0.7 mm for the heat loading of 1.5 MW. From the thin lens theory of beam optics, beamlet deflection angle by the aperture-axis displacement was estimated to be about 2 mrad, which is within the requirement of the engineering design of the ITER-NBI system. Numerical simulation also indicated that no melting on the acceleration grid would occur for a heat loading of 1.5 MW, while local plastic deformation would happen. To avoid the plastic deformation, it is necessary to reduce the heat loading onto the acceleration grid to less than 1 MW

RF accelerating unit installed in the PSB

CERN Multimedia

CERN PhotoLab

1972-01-01

RF accelerating unit installed in the PSB ring between two bending magnets. Cool air from a heat exchanger is injected into the four cavities from the central feeder and the hot air recirculated via the lateral ducts.

Characteristics of diffusion flames with accelerated motion

Directory of Open Access Journals (Sweden)

Lou Bo

2016-01-01

Full Text Available The aim of this work is to present an experiment to study the characteristics of a laminar diffusion flame under acceleration. A Bunsen burner (nozzle diameter 8 mm, using liquefied petroleum gas as its fuel, was ignited under acceleration. The temperature field and the diffusion flame angle of inclination were visualised with the assistance of the visual display technology incorporated in MATLAB™. Results show that the 2-d temperature field under different accelerations matched the variation in average temperatures: they both experience three variations at different time and velocity stages. The greater acceleration has a faster change in average temperature with time, due to the accumulation of combustion heat: the smaller acceleration has a higher average temperature at the same speed. No matter what acceleration was used, in time, the flame angle of inclination increased, but the growth rate decreased until an angle of 90°: this could be explained by analysis of the force distribution within the flame. It is also found that, initially, the growth rate of angle with velocity under the greater acceleration was always smaller than that at lower accelerations; it was also different in flames with uniform velocity fire conditions.

An experimental and analytical study of a buoyancy driven cooling system for a particle accelerator

International Nuclear Information System (INIS)

Campbell, B.; Ranganathan, R.

1993-05-01

A buoyancy driven closed-loop cooling system that transports the heat generated in a particle accelerator to the ambient has been evaluated both through experiments performed earlier and analysis techniques developed elsewhere. Excellent comparisons between measurements and calculations have been obtained. The model illustrates the feasibility (from a heat transfer viewpoint) of such a cooling system for a particle accelerator

An experimental and analytical study of a buoyancy driven cooling system for a particle accelerator

International Nuclear Information System (INIS)

Campbell, B.; Ranganathan, R.

1993-01-01

A buoyancy driven closed-loop cooling system that transports the heat generated in a particle accelerator to the ambient has been evaluated both through experiments performed earlier and analysis techniques developed elsewhere. Excellent comparisons between measurements and calculations have been obtained. The model illustrates the feasibility (from a heat transfer viewpoint) of such a cooling system for a particle accelerator

Free convection film flows and heat transfer

CERN Document Server

Shang, Deyi

2010-01-01

Presents development of systematic studies for hydrodynamics and heat and mass transfer in laminar free convection, accelerating film boiling and condensation of Newtonian fluids, and accelerating film flow of non-Newtonian power-law fluids. This book provides a system of analysis models with a developed velocity component method.

Electromagnetic compression gun for hypervelocity projectile acceleration

International Nuclear Information System (INIS)

Woo, J.T.

1987-01-01

The rapid acceleration of projectiles to very high velocities has applications in many areas. The general requirements for an effective system is simplicity, reliability, compactness and good efficiency. The authors developed a concept by using electromagnetic forces to compressionally heat a plasma to high temperature and pressure to serve as the propellant for the acceleration of projectiles. The concept shares the simplicity of the light gas gun, but because of the high temperature of the propellant, is capable of significantly higher performance. Unlike the electrothermal gun approach to raise the propellant temperature by resistive heating, the electromagnetic concept is more efficient at higher temperatures. Operationally, the concept resembles a railgun in requiring a large pulsed current to drive the system. However, the current flow in this case is entirely external to the gun barrel and is axisymmetric. Therefore, many of the problems associated with railgun operations are avoided. Furthermore, because the current channel is external, there is also greater flexibility in the choice of load impedance to match to the power supply. The concept can also be generalized to a multi-stage regenerative system driven by a pulse forming network to resemble a coaxial accelerator

Final report on the LLNL compact torus acceleration project

International Nuclear Information System (INIS)

Eddleman, J.; Hammer, J.; Hartman, C.; McLean, H.; Molvik, A.

1995-01-01

In this report, we summarize recent work at LLNL on the compact torus (CT) acceleration project. The CT accelerator is a novel technique for projecting plasmas to high velocities and reaching high energy density states. The accelerator exploits magnetic confinement in the CT to stably transport plasma over large distances and to directed kinetic energies large in comparison with the CT internal and magnetic energy. Applications range from heating and fueling magnetic fusion devices, generation of intense pulses of x-rays or neutrons for weapons effects and high energy-density fusion concepts

Chlorophyll loss associated with heat-induced senescence in bentgrass.

Science.gov (United States)

Jespersen, David; Zhang, Jing; Huang, Bingru

2016-08-01

Heat stress-induced leaf senescence is characterized by the loss of chlorophyll from leaf tissues. The objectives of this study were to examine genetic variations in the level of heat-induced leaf senescence in hybrids of colonial (Agrostis capillaris)×creeping bentgrass (Agrostis stolonifera) contrasting in heat tolerance, and determine whether loss of leaf chlorophyll during heat-induced leaf senescence was due to suppressed chlorophyll synthesis and/or accelerated chlorophyll degradation in the cool-season perennial grass species. Plants of two hybrid backcross genotypes ('ColxCB169' and 'ColxCB190') were exposed to heat stress (38/33°C, day/night) for 28 d in growth chambers. The analysis of turf quality, membrane stability, photochemical efficiency, and chlorophyll content demonstrated significant variations in the level of leaf senescence induced by heat stress between the two genotypes, with ColXCB169 exhibiting a lesser degree of decline in chlorophyll content, photochemical efficiency and membrane stability than ColXCB190. The assays of enzymatic activity or gene expression of several major chlorophyll-synthesizing (porphobilinogen deaminase, Mg-chelatase, protochlorophyllide-reductase) and chlorophyll-degrading enzymes (chlorophyllase, pheophytinase, and chlorophyll-degrading peroxidase) indicated heat-induced decline in leaf chlorophyll content was mainly due to accelerated chlorophyll degradation, as manifested by increased gene expression levels of chlorophyllase and pheophytinase, and the activity of pheophytinase (PPH), while chlorophyll-synthesizing genes and enzymatic activities were not differentially altered by heat stress in the two genotypes. The analysis of heat-induced leaf senescence of pph mutants of Arabidopsis further confirmed that PPH could be one enzymes that plays key roles in regulating heat-accelerated chlorophyll degradation. Further research on enzymes responsible in part for the loss of chlorophyll during heat

High Efficiency Water Heating Technology Development Final Report. Part I, Lab/Field Performance Evaluation and Accelerated Life Testing of a Hybrid Electric Heat Pump Water Heater (HPWH)

Energy Technology Data Exchange (ETDEWEB)

Baxter, Van D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Murphy, Richard W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Rice, C. Keith [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Linkous, Randall Lee [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-04-01

DOE has supported efforts for many years with the objective of getting a water heater that uses heat pump technology (aka a heat pump water heater or HPWH) successfully on the residential equipment market. The most recent previous effort (1999-2002) produced a product that performed very well in ORNL-led accelerated durability and field tests. The commercial partner for this effort, Enviromaster International (EMI), introduced the product to the market under the trade name Watter$aver in 2002 but ceased production in 2005 due to low sales. A combination of high sales price and lack of any significant infrastructure for service after the sale were the principal reasons for the failure of this effort. What was needed for market success was a commercial partner with the manufacturing and market distribution capability necessary to allow economies of scale to lead to a viable unit price together with a strong customer service infrastructure. General Electric certainly meets these requirements, and knowing of ORNL s expertise in this area, approached ORNL with the proposal to partner in a CRADA to produce a high efficiency electric water heater. A CRADA with GE was initiated early in Fiscal Year, 2008. GE initially named its product the Hybrid Electric Water Heater (HEWH).

Quick Preparation of Moisture-Saturated Carbon Fiber-Reinforced Plastics and Their Accelerated Ageing Tests Using Heat and Moisture

Directory of Open Access Journals (Sweden)

Masao Kunioka

2016-06-01

Full Text Available A quick method involving the control of heat and water vapor pressure for preparing moisture-saturated carbon fiber-reinforced plastics (CFRP, 8 unidirectional prepreg layers, 1.5 mm thickness, epoxy resin has been developed. The moisture-saturated CFRP sample was obtained at 120 °C and 0.2 MPa water vapor in 72 h by this method using a sterilizer (autoclave. The bending strength and viscoelastic properties measured by a dynamic mechanical analysis (DMA remained unchanged during repetitive saturation and drying steps. No degradation and molecular structural change occurred. Furthermore an accelerated ageing test with two ageing factors, i.e., heat and moisture was developed and performed at 140–160 °C and 0.36–0.62 MPa water vapor pressure by using a sealed pressure-proof stainless steel vessel (autoclave. The bending strength of the sample decreased from 1107 to 319 MPa at 160 °C and 0.63 MPa water vapor pressure in 9 days. Degraded samples were analyzed by DMA. The degree of degradation for samples was analyzed by DMA. CFRP and degraded CFRP samples were analyzed by using a surface and interfacial cutting analysis system (SAICAS and an electron probe micro-analyzer (EPMA equipped in a scanning electron microscope.

Advanced Accelerator Applications University Participation Program

Energy Technology Data Exchange (ETDEWEB)

Y. Chen; A. Hechanova

2007-07-25

Our research tasks span the range of technology areas for transmutation, gas-cooled reactor technology, and high temperature heat exchangers, including separation of actinides from spent nuclear fuel, methods of fuel fabrication, reactor-accelerator coupled experiments, corrosion of materials exposed to lead-bismuth eutectic, and special nuclear materials protection and accountability.

PLASMOID EJECTIONS AND LOOP CONTRACTIONS IN AN ERUPTIVE M7.7 SOLAR FLARE: EVIDENCE OF PARTICLE ACCELERATION AND HEATING IN MAGNETIC RECONNECTION OUTFLOWS

Energy Technology Data Exchange (ETDEWEB)

Liu Wei [Lockheed Martin Solar and Astrophysics Laboratory, Building 252, 3251 Hanover Street, Palo Alto, CA 94304 (United States); Chen Qingrong; Petrosian, Vahe [Department of Physics, Stanford University, Stanford, CA 94305 (United States)

2013-04-20

Where particle acceleration and plasma heating take place in relation to magnetic reconnection is a fundamental question for solar flares. We report analysis of an M7.7 flare on 2012 July 19 observed by SDO/AIA and RHESSI. Bi-directional outflows in forms of plasmoid ejections and contracting cusp-shaped loops originate between an erupting flux rope and underlying flare loops at speeds of typically 200-300 km s{sup -1} up to 1050 km s{sup -1}. These outflows are associated with spatially separated double coronal X-ray sources with centroid separation decreasing with energy. The highest temperature is located near the nonthermal X-ray loop-top source well below the original heights of contracting cusps near the inferred reconnection site. These observations suggest that the primary loci of particle acceleration and plasma heating are in the reconnection outflow regions, rather than the reconnection site itself. In addition, there is an initial ascent of the X-ray and EUV loop-top source prior to its recently recognized descent, which we ascribe to the interplay among multiple processes including the upward development of reconnection and the downward contractions of reconnected loops. The impulsive phase onset is delayed by 10 minutes from the start of the descent, but coincides with the rapid speed increases of the upward plasmoids, the individual loop shrinkages, and the overall loop-top descent, suggestive of an intimate relation of the energy release rate and reconnection outflow speed.

Transient analyses for lead–bismuth cooled accelerator-driven system

International Nuclear Information System (INIS)

Sugawara, Takanori; Nishihara, Kenji; Tsujimoto, Kazufumi

2013-01-01

Highlights: ► The transient analyses for the LBE cooled accelerator-driven system were performed. ► The purpose was to investigate the possibility of the core damage. ► All results except the protected loss of heat sink satisfied the no-damage criteria. - Abstract: The transient analyses for the lead–bismuth cooled Accelerator-Driven System (ADS) were performed with the use of the SIMMER-III and RELAP5/mod3.2 codes to investigate the possibility of the core damage. Five accidents; the beam window breakage, the protected loss of heat sink, the beam overpower, the unprotected loss of flow and the unprotected blockage accident were analyzed as the typical accidents in the ADS. Through these calculations, it was confirmed that all calculation results except the protected loss of heat sink satisfied the no-damage criteria. In the protected loss of heat sink, the cladding tube temperature reached at the melting temperature after 20 h although the calculation condition was very conservative. It is required to design a safety system of the ADS to decrease the frequencies of the accidents and to ease the accidents

Acceleration processes in the magnetospheric plasma: a review

Energy Technology Data Exchange (ETDEWEB)

Nishida, A [Tokyo Univ. (Japan). Inst. of Space and Aeronautical Science

1975-01-01

Our present knowledge on the acceleration process in the magnetospheric plasma is reviewed and major problems are summarized. Acceleration processes can be classified into three categories. First, acceleration can be made by the reconnection process in the magnetotail. The occurrence of reconnection during substorm expansion phases has been confirmed, but details of the energy conversion mechanism need be clarified. Second, acceleration by the electric potential drop along magnetic field lines has been strongly suggested from observations of precipitating particles. The position and structure of the potential layer, however, have not been clarified, and theoretical understanding of the process is still in the early stage of development. Third, particles can be adiabatically heated as they are driven toward the earth in the course of their convective motion. Spatial structure and dynamical development of the auroral precipitation pattern represent both challenge and clue to the understanding of the magnetospheric acceleration process.

State registration and inspection programs for particle accelerators

International Nuclear Information System (INIS)

Bailey, E.D.

1976-01-01

The Suggested State Regulations for Control of Radiation(SSRCR) are recommended by the Council of State Governments and the National Conference of Radiation Control Program Directors as the model regulations which states should adopt in order to have adequate regulation and uniformity from state to state. These regulations are used as a basis for reviewing the current status of accelerator regulation in each state. The SSRCR does contain a separate part for registration (Part B--Registration of Radiation Machine Facilities and Services) and a separate part (Part I--Radiation Safety Requirements for Particle Accelerators) with specific requirements for the possession and use of accelerators. In addition, medical accelerators have additional requirements in Part F--X-Rays in The Heating Acts. These regulations specify requirements related to limitations of use, shielding and safety design requirements, control and interlock systems, warning devices, operating procedures, radiation monitoring, and calibration of medical accelerators

Theoretical temperature model with experimental validation for CLIC Accelerating Structures

CERN Document Server

AUTHOR|(CDS)2126138; Vamvakas, Alex; Alme, Johan

Micron level stability of the Compact Linear Collider (CLIC) components is one of the main requirements to meet the luminosity goal for the future $48 \\,km$ long underground linear accelerator. The radio frequency (RF) power used for beam acceleration causes heat generation within the aligned structures, resulting in mechanical movements and structural deformations. A dedicated control of the air- and water- cooling system in the tunnel is therefore crucial to improve alignment accuracy. This thesis investigates the thermo-mechanical behavior of the CLIC Accelerating Structure (AS). In CLIC, the AS must be aligned to a precision of $10\\,\\mu m$. The thesis shows that a relatively simple theoretical model can be used within reasonable accuracy to predict the temperature response of an AS as a function of the applied RF power. During failure scenarios or maintenance interventions, the RF power is turned off resulting in no heat dissipation and decrease in the overall temperature of the components. The theoretica...

Studies of hydrogen pellet acceleration by electric arc discharge

International Nuclear Information System (INIS)

Andersen, S.

1986-01-01

A preliminary design for an arc heated gas gun is described. The experimental development of the final design constitutes the final phase in contract work for JET. The gun consist of a cryogenic arc chamber connected to the inlet of a gun barrel. With a dose of H 2 -gas condensed in the arc chamber and a D 2 -pellet punch loaded into the barrel the gun is fired by the ignition of an electrical discharge in the arc chamber. The pellet is accelerated by the exhaust of hot H 2 -gas from the arc chamber and its velocity and acceleration is measured by time-of-flight along and outside the barrel. The pressure development by the arc is monitored by pressure transducers as well in the arc chamber as in the barrel. The performance of the gun is described in terms of arc current and voltage versus time as functions of power supply configuration and H 2 propellant dose. The time behaviour of the propellant pressure in the arc chamber and in the barrel is shown in relation to the arc current. Pellet acceleration and pressure development in the gun barrel for the arc heated gas gun is discussed and compared to results obtained by conventional fast valve acceleration

Acquisition system for the diagnostics data from a toroidal machine

International Nuclear Information System (INIS)

Moulin, B.

1976-01-01

The data acquisition system 'ARIANE' has been conceived by the SIG (Service d'Ionique Generale), for physical measurements on the toroidal machines PETULA and WEGA, which were designed to study the H.F. heating of pulsed plasmas. These systems are constitued of electronic modules which permit them to be adapted to different kinds of measurements, either by analogue channels or by pulse counting. The programmation of these systems, are achieved, either by multiswitches accessible manually on front panels, or by a computer which performs the numerical computations [fr

Experimental study of laser acceleration of planar targets at the wavelength 0.26 μm

International Nuclear Information System (INIS)

Fabbro, R.; Faral, B.; Cottet, F.; Romain, J.P.

1984-01-01

The main characteristics of accelerated aluminum targets, which are the target velocity, the uniformity of the acceleration and the backside temperature have been studied in laser experiments performed at wavelength 0.26 μm with an absorbed flux of a few 10 13 W/cm 2 , in 400-ps pulse duration by using the double-foil technique and an optical pyrometry diagnostic: The ablation pressure was inferred from the velocity measurements. The uniformity of the acceleration was shown to be controlled by the hot spots in the focal spot, and the importance of studying the smoothing of laser inhomogeneities for accelerated targets with large ablated fractions was emphasized. The observed dependence of the backside temperature as a function of the initial foil thickness is discussed in the light of shock wave heating and radiative heating

Ablation acceleration of macroparticle in spiral magnetic fields

International Nuclear Information System (INIS)

Ikuta, Kazunari.

1981-05-01

The rocket motion of macroparticles heated by energetic pulses in a spiral magnetic field was studied. The purpose of the present work is to study the ablation acceleration of a macroparticle in a spiral magnetic field with the help of the law of conservation of angular momentum. The basic equation of motion of ablatively accelerated projectile in a spiral magnetic field was derived. Any rocket which is ejecting fully ionized plasma in an intense magnetic field with rotational transform is able to have spin by the law of conservation of momentum. The effect of spiral magnetic field on macroparticle acceleration is discussed. The necessary mass ratio increase exponentially with respect to the field parameter. The spiral field should be employed with care to have only to stabilize the position of macroparticles. As conclusion, it can be said that the ablation acceleration of the projectile in a spiral field can give the accelerated body spin quite easily. (Kato, T.)

Investigation of advanced propulsion technologies: The RAM accelerator and the flowing gas radiation heater

Science.gov (United States)

Bruckner, A. P.; Knowlen, C.; Mattick, A. T.; Hertzberg, A.

1992-01-01

The two principal areas of advanced propulsion investigated are the ram accelerator and the flowing gas radiation heater. The concept of the ram accelerator is presented as a hypervelocity launcher for large-scale aeroballistic range applications in hypersonics and aerothermodynamics research. The ram accelerator is an in-bore ramjet device in which a projectile shaped like the centerbody of a supersonic ramjet is propelled in a stationary tube filled with a tailored combustible gas mixture. Combustion on and behind the projectile generates thrust which accelerates it to very high velocities. The acceleration can be tailored for the 'soft launch' of instrumented models. The distinctive reacting flow phenomena that have been observed in the ram accelerator are relevant to the aerothermodynamic processes in airbreathing hypersonic propulsion systems and are useful for validating sophisticated CFD codes. The recently demonstrated scalability of the device and the ability to control the rate of acceleration offer unique opportunities for the use of the ram accelerator as a large-scale hypersonic ground test facility. The flowing gas radiation receiver is a novel concept for using solar energy to heat a working fluid for space power or propulsion. Focused solar radiation is absorbed directly in a working gas, rather than by heat transfer through a solid surface. Previous theoretical analysis had demonstrated that radiation trapping reduces energy loss compared to that of blackbody receivers, and enables higher efficiencies and higher peak temperatures. An experiment was carried out to measure the temperature profile of an infrared-active gas and demonstrate the effect of radiation trapping. The success of this effort validates analytical models of heat transfer in this receiver, and confirms the potential of this approach for achieving high efficiency space power and propulsion.

Thermal Hydraulic Design of PWT Accelerating Structures

CERN Document Server

Yu, David; Chen Ping; Lundquist, Martin; Luo, Yan

2005-01-01

Microwave power losses on the surfaces of accelerating structures will transform to heat which will deform the structures if it is not removed in time. Thermal hydraulic design of the disk and cooling rods of a Plane Wave Transformer (PWT) structure is presented. Experiments to measure the hydraulic (pressure vs flow rate) and cooling (heat removed vs flow rate) properties of the PWT disk are performed, and results compared with simulations using Mathcad models and the COSMOSM code. Both experimental and simulation results showed that the heat deposited on the structure could be removed effectively using specially designed water-cooling circuits and the temperature of the structure could be controlled within the range required.

Fast-acting calorimeter measures heat output of plasma gun accelerator

Science.gov (United States)

Dethlefson, R.; Larson, A. V.; Liebing, L.

1967-01-01

Calorimeter measures the exhaust energy from a shot of a pulsed plasma gun accelerator. It has a fast response time and requires only one measurement to determine the total energy. It uses a long ribbon of copper foil wound around a glass frame to form a reentrant cavity.

Heat pipe applications workshop report

International Nuclear Information System (INIS)

Ranken, W.A.

1978-04-01

The proceedings of the Heat Pipe Applications Workshop, held at the Los Alamos Scientific Laboratory October 20-21, 1977, are reported. This workshop, which brought together representatives of the Department of Energy and of a dozen industrial organizations actively engaged in the development and marketing of heat pipe equipment, was convened for the purpose of defining ways of accelerating the development and application of heat pipe technology. Recommendations from the three study groups formed by the participants are presented. These deal with such subjects as: (1) the problem encountered in obtaining support for the development of broadly applicable technologies, (2) the need for applications studies, (3) the establishment of a heat pipe technology center of excellence, (4) the role the Department of Energy might take with regard to heat pipe development and application, and (5) coordination of heat pipe industry efforts to raise the general level of understanding and acceptance of heat pipe solutions to heat control and transfer problems

Nonlinear predictive control in the LHC accelerator

CERN Document Server

Blanco, E; Cristea, S; Casas, J

2009-01-01

This paper describes the application of a nonlinear model-based control strategy in a real challenging process. A predictive controller based on a nonlinear model derived from physical relationships, mainly heat and mass balances, has been developed and commissioned in the inner triplet heat exchanger unit (IT-HXTU) of the large hadron collider (LHC) particle accelerator at European Center for Nuclear Research (CERN). The advanced regulation\\ maintains the magnets temperature at about 1.9 K. The development includes a constrained nonlinear state estimator with a receding horizon estimation procedure to improve the regulator predictions.

MEMS-based, RF-driven, compact accelerators

Science.gov (United States)

Persaud, A.; Seidl, P. A.; Ji, Q.; Breinyn, I.; Waldron, W. L.; Schenkel, T.; Vinayakumar, K. B.; Ni, D.; Lal, A.

2017-10-01

Shrinking existing accelerators in size can reduce their cost by orders of magnitude. Furthermore, by using radio frequency (RF) technology and accelerating ions in several stages, the applied voltages can be kept low paving the way to new ion beam applications. We make use of the concept of a Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) and have previously shown the implementation of its basic components using printed circuit boards, thereby reducing the size of earlier MEQALACs by an order of magnitude. We now demonstrate the combined integration of these components to form a basic accelerator structure, including an initial beam-matching section. In this presentation, we will discuss the results from the integrated multi-beam ion accelerator and also ion acceleration using RF voltages generated on-board. Furthermore, we will show results from Micro-Electro-Mechanical Systems (MEMS) fabricated focusing wafers, which can shrink the dimension of the system to the sub-mm regime and lead to cheaper fabrication. Based on these proof-of-concept results we outline a scaling path to high beam power for applications in plasma heating in magnetized target fusion and in neutral beam injectors for future Tokamaks. This work was supported by the Office of Science of the US Department of Energy through the ARPA-e ALPHA program under contracts DE-AC02-05CH11231.

Boundary layer flow of MHD generalized Maxwell fluid over an exponentially accelerated infinite vertical surface with slip and Newtonian heating at the boundary

Science.gov (United States)

Imran, M. A.; Riaz, M. B.; Shah, N. A.; Zafar, A. A.

2018-03-01

The aim of this article is to investigate the unsteady natural convection flow of Maxwell fluid with fractional derivative over an exponentially accelerated infinite vertical plate. Moreover, slip condition, radiation, MHD and Newtonian heating effects are also considered. A modern definition of fractional derivative operator recently introduced by Caputo and Fabrizio has been used to formulate the fractional model. Semi analytical solutions of the dimensionless problem are obtained by employing Stehfest's and Tzou's algorithms in order to find the inverse Laplace transforms for temperature and velocity fields. Temperature and rate of heat transfer for non-integer and integer order derivatives are computed and reduced to some known solutions from the literature. Finally, in order to get insight of the physical significance of the considered problem regarding velocity and Nusselt number, some graphical illustrations are made using Mathcad software. As a result, in comparison between Maxwell and viscous fluid (fractional and ordinary) we found that viscous (fractional and ordinary) fluids are swiftest than Maxwell (fractional and ordinary) fluids.

A New Damped and Tapered Accelerating Structure for CLIC

CERN Document Server

Raguin, J Y; Syratchev, I V; Wilson, Ian H; Wuensch, Walter

2002-01-01

The main performance limits when designing accelerating structures for the Compact Linear Collider (CLIC) for an average accelerating gradient above 100 MV/m are electrical breakdown and material fatigue caused by pulsed surface heating. In addition, for stable beam operation, the structures should have low short-range transverse wakefields and much-reduced transverse and longitudinal long-range wakefields. Two damped and tapered accelerating structures have been designed. The first has an accelerating gradient of 112 MV/m with the surface electrical field limited to 300 MV/m and the maximum temperature increase limited to 100°C. The second, with an accelerating gradient of 150 MV/m, has a peak surface electrical field of 392 MV/m and a maximum temperature increase of 167°C. Innovations to the cell and damping waveguide geometry and to the tapering of the structures are presented, and possible further improvements are proposed.

Experimental study of laser acceleration of planar targets at the wavelength 0. 26. mu. m

Energy Technology Data Exchange (ETDEWEB)

Fabbro, R.; Faral, B.; Cottet, F.; Romain, J.P.

1984-12-01

The main characteristics of accelerated aluminum targets, which are the target velocity, the uniformity of the acceleration and the backside temperature have been studied in laser experiments performed at wavelength 0.26 ..mu..m with an absorbed flux of a few 10/sup 13/ W/cm/sup 2/, in 400-ps pulse duration by using the double-foil technique and an optical pyrometry diagnostic: The ablation pressure was inferred from the velocity measurements. The uniformity of the acceleration was shown to be controlled by the hot spots in the focal spot, and the importance of studying the smoothing of laser inhomogeneities for accelerated targets with large ablated fractions was emphasized. The observed dependence of the backside temperature as a function of the initial foil thickness is discussed in the light of shock wave heating and radiative heating.

Ripple losses during ICRF heating in Tore Supra

International Nuclear Information System (INIS)

Basiuk, V.; Eriksson, L.-G.; Bergeaud, V.; Chantant, M.; Martin, G.; Nguyen, F.; Reichle, R.; Vallet, J.C.; Delpeche, L.; Surle, F.

2004-01-01

The toroidal field coils in Tore Supra are supra-conducting, and their number is restricted to 18. As a result, the ripple is fairly large, about 7% at the plasma boundary. Tore Supra has consequently been equipped with dedicated ripple loss diagnostics, which has allowed ripple loss studies. This paper reports on the measurements made with these diagnostics and provides an analysis of the experimental results, comparing them with theoretical expectations whenever possible. Furthermore, the main heating source accelerating ions in Tore Supra is ion cyclotron resonance range of frequency (ICRF) heating, and the paper provides new information on the ripple losses of ICRF accelerated ions. (author)

Stability of superconducting Rutherford cables for accelerator magnets

NARCIS (Netherlands)

Willering, G.P.

2009-01-01

The stability of superconducting magnets has a high priority for particle accelerators, since the operational time and operational collision energy depend strongly on it. Local heat dissipation due to beam loss and conductor movement is inevitable, causing local hot spots in the conductor, possibly

Numerical Analysis of Microwave Heating on Saponification Reaction

Science.gov (United States)

Huang, Kama; Jia, Kun

2005-01-01

Currently, microwave is widely used in chemical industry to accelerate chemical reactions. Saponification reaction has important applications in industry; some research results have shown that microwave heating can significantly accelerate the reaction [1]. But so far, no efficient method has been reported for the analysis of the heating process and design of an efficient reactor powered by microwave. In this paper, we present a method to study the microwave heating process on saponification reaction, where the reactant in a test tube is considered as a mixture of dilute solution. According to the preliminary measurement results, the effective permittivity of the mixture is approximately the permittivity of water, but the conductivity, which could change with the reaction, is derived from the reaction equation (RE). The electromagnetic field equation and reaction equation are coupled by the conductivity. Following that, the whole heating processes, which is described by Maxwell's equations, the reaction equation and heat transport equation (HTE), is analyzed by finite difference time domain (FDTD) method. The temperature rising in the test tube are measured and compared with the computational results. Good agreement can be seen between the measured and calculated results.

Development of laser heated high current DC electron gun

International Nuclear Information System (INIS)

Banerjee, Srutarshi; Bhattacharjee, Dhruva; Kandaswamy, E.; Ghodke, S.R.; Tiwari, Rajnish; Bakhtsingh, R.I.

2015-01-01

The paper deals with the development of a Laser heated cathode for Electron Accelerator. The electron gun is meant for Megawatt-class DC Accelerator for Electron Beam Flue Gas Treatment applications. Conventionally, LaB 6 cathode is indirectly heated by tungsten filaments whereas in the newly proposed gun, Laser is utilized for heating. A Nd:YAG Laser is used to heat the LaB 6 cathode to emission temperatures. The characterization of cathode heating at various Laser powers has been carried out. In initial trials, it has been observed that with 125 W of Laser power, the LaB 6 pellet was heated to 1315 ° C. Based on these experimental results, an electron gun rated for 30 kV, 350 mA CW has been designed. The optimization of gun electrode geometry has been done using CST Particle Studio in order to tune the various electron gun parameters. The beam diameter obtained in simulation is 8 mm at 100 mm from the LaB 6 cathode. The perveance obtained is 7.1 x 10 -8 A/V 3/2 . The Laser heated cathode has the advantages of eliminating the magnetic field effects of filament on the electron beam, electrical isolation needed for gun filament power supplies and better electron beam emittances. (author)

Microwave Heating of Synthetic Skin Samples for Potential Treatment of Gout Using the Metal-Assisted and Microwave-Accelerated Decrystallization Technique.

Science.gov (United States)

Toker, Salih; Boone-Kukoyi, Zainab; Thompson, Nishone; Ajifa, Hillary; Clement, Travis; Ozturk, Birol; Aslan, Kadir

2016-11-30

Physical stability of synthetic skin samples during their exposure to microwave heating was investigated to demonstrate the use of the metal-assisted and microwave-accelerated decrystallization (MAMAD) technique for potential biomedical applications. In this regard, optical microscopy and temperature measurements were employed for the qualitative and quantitative assessment of damage to synthetic skin samples during 20 s intermittent microwave heating using a monomode microwave source (at 8 GHz, 2-20 W) up to 120 s. The extent of damage to synthetic skin samples, assessed by the change in the surface area of skin samples, was negligible for microwave power of ≤7 W and more extensive damage (>50%) to skin samples occurred when exposed to >7 W at initial temperature range of 20-39 °C. The initial temperature of synthetic skin samples significantly affected the extent of change in temperature of synthetic skin samples during their exposure to microwave heating. The proof of principle use of the MAMAD technique was demonstrated for the decrystallization of a model biological crystal (l-alanine) placed under synthetic skin samples in the presence of gold nanoparticles. Our results showed that the size (initial size ∼850 μm) of l-alanine crystals can be reduced up to 60% in 120 s without damage to synthetic skin samples using the MAMAD technique. Finite-difference time-domain-based simulations of the electric field distribution of an 8 GHz monomode microwave radiation showed that synthetic skin samples are predicted to absorb ∼92.2% of the microwave radiation.

Microwave Heating of Synthetic Skin Samples for Potential Treatment of Gout Using the Metal-Assisted and Microwave-Accelerated Decrystallization Technique

Science.gov (United States)

2016-01-01

Physical stability of synthetic skin samples during their exposure to microwave heating was investigated to demonstrate the use of the metal-assisted and microwave-accelerated decrystallization (MAMAD) technique for potential biomedical applications. In this regard, optical microscopy and temperature measurements were employed for the qualitative and quantitative assessment of damage to synthetic skin samples during 20 s intermittent microwave heating using a monomode microwave source (at 8 GHz, 2–20 W) up to 120 s. The extent of damage to synthetic skin samples, assessed by the change in the surface area of skin samples, was negligible for microwave power of ≤7 W and more extensive damage (>50%) to skin samples occurred when exposed to >7 W at initial temperature range of 20–39 °C. The initial temperature of synthetic skin samples significantly affected the extent of change in temperature of synthetic skin samples during their exposure to microwave heating. The proof of principle use of the MAMAD technique was demonstrated for the decrystallization of a model biological crystal (l-alanine) placed under synthetic skin samples in the presence of gold nanoparticles. Our results showed that the size (initial size ∼850 μm) of l-alanine crystals can be reduced up to 60% in 120 s without damage to synthetic skin samples using the MAMAD technique. Finite-difference time-domain-based simulations of the electric field distribution of an 8 GHz monomode microwave radiation showed that synthetic skin samples are predicted to absorb ∼92.2% of the microwave radiation. PMID:27917407

Variation of Mechanical Properties of High RRR And Reactor Grade Niobium With Heat Treatments

Energy Technology Data Exchange (ETDEWEB)

Ganapati Myneni; H. Umezawa

2003-06-01

Superconducting rf cavities used as accelerating structures in particle accelerators are made from high purity niobium with residual resistance ratios greater than 250. Reactor grade niobium is also used to make wave-guide and/or end group components for these accelerating structures. The major impurities in this type of niobium are interstitially dissolved gases such as hydrogen, nitrogen, and oxygen in addition to carbon. After fabricating the niobium accelerating structures, they are subjected to heat treatments for several hours in vacuum at temperatures of up to 900 C for degassing hydrogen or up to 1400 C for improving the thermal conductivity of niobium considerably. These heat treatments are affecting the mechanical properties of niobium drastically. In this paper the variation of the mechanical properties of high purity and reactor grade niobium with heat treatments in a vacuum of {approx} 10{sup -6} Torr and temperatures from 600 C to 1250 C for periods of 10 to 6 hours are presented.

Assessment of surface hardness of acrylic resins submitted to accelerated artificial aging.

Science.gov (United States)

Tornavoi, D C; Agnelli, J A M; Lepri, C P; Mazzetto, M O; Botelho, A L; Soares, R G; Dos Reis, A C

2012-06-01

The aim of this study was to assess the influence of accelerated artificial aging (AAA) on the surface hardness of acrylic resins. The following three commercial brands of acrylic resins were tested: Vipi Flash (autopolymerized resin), Vipi Wave (microwave heat-polymerized resin) and Vipi Cril (conventional heat-polymerized resin). To perform the tests, 21 test specimens (65x10x3 mm) were made, 7 for each resin. Three surface hardness readings were performed for each test specimen, before and after AAA, and the means were submitted to the following tests: Kolmogorov-Smirnov (P>0.05), Levene Statistic, Two-way ANOVA, Tukey Post Hoc (Paging, the autopolymerized acrylic resin Vipi Flash showed lower hardness values when compared with the heat-polymerized resin Vipi Cril (P=0.001). After aging, the 3 materials showed similar performance when compared among them. The Vipi Cril was the only one affected by AAA and showed lower hardness values after this procedure (Pp=0.003). It may be concluded that accelerated artificial aging influenced surface hardness of heat-polymerized acrylic resin Vipi Cril.

Cosmic ray acceleration by stellar wind. Simulation for heliosphere

International Nuclear Information System (INIS)

Petukhov, S.I.; Turpanov, A.A.; Nikolaev, V.S.

1985-01-01

The solar wind deceleration by the interstellar medium may result in the existence of the solar wind terminal shock. In this case a certain fraction of thermal particles after being heated at the shock would obtain enough energy to be injected to the regular acceleration process. An analytical solution for the spectrum in the frame of a simplified model that includes particle acceleration at the shock front and adiabatic cooling inside the stellar wind cavity has been derived. It is shown that the acceleration of the solar wind particles at the solar wind terminal shock is capable of providing the total flux, spectrum and radial gradients of the low-energy protons close to one observed in the interplanetary space

Acceleration of heavy-ion beams at the SF cyclotron

International Nuclear Information System (INIS)

Sakurada, Yuzo; Yamazaki, Tsutomu.

1984-10-01

With the development of the new arc-heated cathode PIG type source, heavy-ion acceleration in the SF cyclotron has been drastically augmented, which means that a stable routine operation is being realized as well as the number of ion species is increasing. Excellent performance is also being exhibited with the arc power supply and gas feeding system required for the operation of the heavy-ion source. At present, the gaseous ions which are being accelerated are as follows: He, B, C, N, O, F, Ne, S, Ar and Xe. In the meantime, the metallic ions which are being accelerated likewise are Li, Be, Na, Mg, Al, Si, Cl, Ca, Ti, Fe and Cu. In this paper, results of mainly the research of heavy-ion acceleration conducted during the period from 1983 to July 1984 are described. (author)

Investigation of electron heating in laser-plasma interaction

Directory of Open Access Journals (Sweden)

A Parvazian

2013-03-01

Full Text Available  In this paper, stimulated Raman scattering (SRS and electron heating in laser plasma propagating along the plasma fusion is investigated by particle-in cell simulation. Applying an external magnetic field to plasma, production of whistler waves and electron heating associated with whistler waves in the direction perpendicular to external magnetic field was observed in this simulation. The plasma waves with low phase velocities, generated in backward-SRS and dominateing initially in time and space, accelerated the backward electrons by trapping them. Then these electrons promoted to higher energies by the forward-SRS plasma waves with high phase velocities. This tow-stage electron acceleration is more efficient due to the coexistence of these two instabilities.

Investigation of electron heating in laser-plasma interaction

International Nuclear Information System (INIS)

Parvazian, A.; Haji Sharifi, K.

2013-01-01

In this paper, stimulated Raman scattering and electron heating in laser plasma propagating along the plasma fusion is investigated by particle-in cell simulation. Applying an external magnetic field to plasma, production of whistler waves and electron heating associated with whistler waves in the direction perpendicular to external magnetic field was observed in this simulation. The plasma waves with low phase velocities, generated in backward-stimulated Raman scattering and dominating initially in time and space, accelerated the backward electrons by trapping them. Then these electrons promoted to higher energies by the forward-stimulated Raman scattering plasma waves with high phase velocities. This two-stage electron acceleration is more efficient due to the coexistence of these two instabilities.

Micro thrust and heat generator

Science.gov (United States)

Garcia, E.J.

1998-11-17

A micro thrust and heat generator have a means for providing a combustion fuel source to an ignition chamber of the micro thrust and heat generator. The fuel is ignited by a ignition means within the micro thrust and heat generator`s ignition chamber where it burns and creates a pressure. A nozzle formed from the combustion chamber extends outward from the combustion chamber and tappers down to a narrow diameter and then opens into a wider diameter where the nozzle then terminates outside of said combustion chamber. The pressure created within the combustion chamber accelerates as it leaves the chamber through the nozzle resulting in pressure and heat escaping from the nozzle to the atmosphere outside the micro thrust and heat generator. The micro thrust and heat generator can be microfabricated from a variety of materials, e.g., of polysilicon, on one wafer using surface micromachining batch fabrication techniques or high aspect ratio micromachining techniques (LIGA). 30 figs.

Heat Transfer and Entropy Generation Analysis of an Intermediate Heat Exchanger in ADS

Science.gov (United States)

Wang, Yongwei; Huai, Xiulan

2018-04-01

The intermediate heat exchanger for enhancement heat transfer is the important equipment in the usage of nuclear energy. In the present work, heat transfer and entropy generation of an intermediate heat exchanger (IHX) in the accelerator driven subcritical system (ADS) are investigated experimentally. The variation of entropy generation number with performance parameters of the IHX is analyzed, and effects of inlet conditions of the IHX on entropy generation number and heat transfer are discussed. Compared with the results at two working conditions of the constant mass flow rates of liquid lead-bismuth eutectic (LBE) and helium gas, the total pumping power all tends to reduce with the decreasing entropy generation number, but the variations of the effectiveness, number of transfer units and thermal capacity rate ratio are inconsistent, and need to analyze respectively. With the increasing inlet mass flow rate or LBE inlet temperature, the entropy generation number increases and the heat transfer is enhanced, while the opposite trend occurs with the increasing helium gas inlet temperature. The further study is necessary for obtaining the optimized operation parameters of the IHX to minimize entropy generation and enhance heat transfer.

Development of an accelerated test for Internal Sulfate Attack study

Directory of Open Access Journals (Sweden)

Khelil Nacim

2014-04-01

Full Text Available Internal Sulfate Attack (ISA is a pathology that occurs under certain conditions in concrete having undergone heating above 70 °C at early age (through heating in pre-casting industry or due to hydration in large concrete parts. This reaction deemed very slow, numerous methods to speed up reactions leading to delayed ettringite formation have been developed. These methods are all based on the material damage. Another type of test is currently under development. It is based on rehabilitation techniques such as electrochemical chloride extraction (ECE in order to accelerate the leaching of alkalis that could be one of the triggers of the pathology. The study presented in this paper focused on concrete specimens prepared from cement (CEM I 52.5 N enriched with Na2SO4. These concretes have undergone a heat treatment typical of those used in precast plants (up to 24 hours with a maximum temperature of 80 °C. Various paths were explored for the development of the accelerated test. The first results showed that it was necessary to use a removable titanium anode ruthenium anode instead of stainless steel embedded in the concrete. Then tests with de-ionized water as the solute to the cathode did not accelerate the onset of expansions. The experiment has been modified and potassium carbonate was added to the solution. This modification didn’t show any significant improvement, and other experiments are being carried out to explain this result.

Drag of a growing bubble at rectilinear accelerated ascension in pure liquids and binary solutions

Directory of Open Access Journals (Sweden)

Ašković Radomir

2003-01-01

Full Text Available The problem of predicting the drag coefficient of a growing bubble at rectilinear accelerated ascension in uniformly super­heated pure liquids and in binary solutions with a non-volatile solute at large Reynolds and Peclet numbers is discussed. In the case of pure liquids, the general solution for the drag coefficient of an accelerated growing bubble from its inception at the critical radius and through the surface-tension-, inertia-, and heat-diffusion-controlled regimes is established, as well as some necessary adaptations in the case of binary solutions with a non-volatile solute. Two particular limiting regimes in the case of pure liquids, inertia-controlled and heat-diffusion-controlled regimes, respectively, are analyzed in details, with satisfactory results. .

Impact of water hardness on energy consumption of geyser heating ...

African Journals Online (AJOL)

Therefore, the Eskom Research, Testing, and Development Business Unit embarked on a study to examine total water hardness as a chemical parameter that may impact the power consumption of electrical geyser heating elements. An accelerated scaling method was developed to lime-scale the geyser heating elements ...

Solar wind acceleration in coronal holes

International Nuclear Information System (INIS)

Kopp, R.A.

1978-01-01

Past attempts to explain the large solar wind velocities in high speed streams by theoretical models of the expansion have invoked either extended nonthermal heating of the corona, heat flux inhibition, or direct addition of momentum to the expanding coronal plasma. Several workers have shown that inhibiting the heat flux at low coronal densities is probably not adequate to explain quantitatively the observed plasma velocities in high speed streams. It stressed that, in order to account for both these large plasma velocities and the low densities found in coronal holes (from which most high speed streams are believed to emanate), extended heating by itself will not suffice. One needs a nonthermal mechanism to provide the bulk acceleration of the high wind plasma close to the sun, and the most likely candidate at present is direct addition of the momentum carried by outward-propagating waves to the expanding corona. Some form of momentum addition appears to be absolutely necessary if one hopes to build quantitatively self-consistent models of coronal holes and high speed solar wind streams

Ion accelerators for space

International Nuclear Information System (INIS)

Slobodrian, R.J.; Potvin, L.

1991-01-01

The main purpose of the accelerators is to allow ion implantation in space stations and their neighborhoods. There are several applications of interest immediately useful in such environment: as ion engines and thrusters, as implanters for material science and for hardening of surfaces (relevant to improve resistance to micrometeorite bombardment of exposed external components), production of man made alloys, etc. The microgravity environment of space stations allows the production of substances (crystalline and amorphous) under conditions unknown on earth, leading to special materials. Ion implantation in situ of those materials would thus lead uninterruptedly to new substances. Accelerators for space require special design. On the one hand it is possible to forego vacuum systems simplifying the design and operation but, on the other hand, it is necessary to pay special attention to heat dissipation. Hence it is necessary to construct a simulator in vacuum to properly test prototypes under conditions prevailing in space

Particle Acceleration in Multiple Dissipation Regions

OpenAIRE

Arzner, Kaspar; Vlahos, Loukas

2004-01-01

The sharp magnetic discontinuities which naturally appear in solar magnetic flux tubes driven by turbulent photospheric motions are associated with intense currents. \\citet{Par83} proposed that these currents can become unstable to a variety of microscopic processes, with the net result of dramatically enhanced resistivity and heating (nanoflares). The electric fields associated with such ``hot spots'' are also expected to enhance particle acceleration. We test this hypothesis by exact relati...

Industrial applications of electron accelerators

International Nuclear Information System (INIS)

Singh, A.

1994-01-01

The interaction of high-energy radiation with organic systems produces very reactive, short-lived, ionic and free-radical species. The chemical changes brought about by these species are very useful in several systems, and are the basis of the growth of the electron processing industry. Some typical areas of the industrial use of electron accelerators are crosslinking wire and cable insulation, manufacturing heat shrink plastic items, curing coatings, and partially curing rubber products. Electron accelerators are also being considered in other areas such as sewage treatment, sterilizing medical disposables, and food irradiation. An emerging application of industrial electron accelerators is the production of advanced composites for the aerospace and other industries. Traditionally, the carbon-, aramid- and glass-fibre-reinforced composites with epoxy matrices are produced by thermal curing. However, equivalent composites with acrylated-epoxy matrices can be made by electron curing. Cost estimates suggest that electron curing could be more economical than thermal curing. Food irradiation has traditionally been an application for 60 Co γ-radiation. With the increasing demand for food irradiation in various countries, it may become necessary to use electron accelerators for this purpose. Since the dose rate during gamma and electron irradiation are generally very different, a review of the relevant work on the effect of dose rates has been done. This paper presents an overview of the industrial applications of electron accelerator for radiation processing, emphasises the electron curing of advanced composites and, briefly reviews the dose-rate effects in radiation processing of advanced composites and food irradiation. (author). 84 refs., 8 tabs

Inherent Safety Features and Passive Prevention Approaches for Pb/Bi-cooled Accelerator-Driven Systems

Energy Technology Data Exchange (ETDEWEB)

Carlsson, Johan

2003-03-01

This thesis is devoted to the investigation of passive safety and inherent features of subcritical nuclear transmutation systems - accelerator-driven systems. The general objective of this research has been to improve the safety performance and avoid elevated coolant temperatures in worst-case scenarios like unprotected loss-of-flow accidents, loss-of-heat-sink accidents, and a combination of both these accident initiators. The specific topics covered are emergency decay heat removal by reactor vessel auxiliary cooling systems, beam shut-off by a melt-rupture disc, safety aspects from locating heat-exchangers in the riser of a pool-type reactor system, and reduction of pressure resistance in the primary circuit by employing bypass routes. The initial part of the research was focused on reactor vessel auxiliary cooling systems. It was shown that an 80 MW{sub th} Pb/Bi-cooled accelerator-driven system of 8 m height and 6 m diameter vessel can be well cooled in the case of loss-of-flow accidents in which the accelerator proton beam is not switched off. After a loss-of-heat-sink accident the proton beam has to be interrupted within 40 minutes in order to avoid fast creep of the vessel. If a melt-rupture disc is included in the wall of the beam pipe, which breaks at 150 K above the normal core outlet temperature, the grace period until the beam has to be shut off is increased to 6 hours. For the same vessel geometry, but an operating power of 250 MW{sub th} the structural materials can still avoid fast creep in case the proton beam is shut off immediately. If beam shut-off is delayed, additional cooling methods are needed to increase the heat removal. Investigations were made on the filling of the gap between the guard and the reactor vessel with liquid metal coolant and using water spray cooling on the guard vessel surface. The second part of the thesis presents examinations regarding an accelerator-driven system also cooled with Pb/Bi but with heat-exchangers located

Inherent Safety Features and Passive Prevention Approaches for Pb/Bi-cooled Accelerator-Driven Systems

International Nuclear Information System (INIS)

Carlsson, Johan

2003-03-01

This thesis is devoted to the investigation of passive safety and inherent features of subcritical nuclear transmutation systems - accelerator-driven systems. The general objective of this research has been to improve the safety performance and avoid elevated coolant temperatures in worst-case scenarios like unprotected loss-of-flow accidents, loss-of-heat-sink accidents, and a combination of both these accident initiators. The specific topics covered are emergency decay heat removal by reactor vessel auxiliary cooling systems, beam shut-off by a melt-rupture disc, safety aspects from locating heat-exchangers in the riser of a pool-type reactor system, and reduction of pressure resistance in the primary circuit by employing bypass routes. The initial part of the research was focused on reactor vessel auxiliary cooling systems. It was shown that an 80 MW th Pb/Bi-cooled accelerator-driven system of 8 m height and 6 m diameter vessel can be well cooled in the case of loss-of-flow accidents in which the accelerator proton beam is not switched off. After a loss-of-heat-sink accident the proton beam has to be interrupted within 40 minutes in order to avoid fast creep of the vessel. If a melt-rupture disc is included in the wall of the beam pipe, which breaks at 150 K above the normal core outlet temperature, the grace period until the beam has to be shut off is increased to 6 hours. For the same vessel geometry, but an operating power of 250 MW th the structural materials can still avoid fast creep in case the proton beam is shut off immediately. If beam shut-off is delayed, additional cooling methods are needed to increase the heat removal. Investigations were made on the filling of the gap between the guard and the reactor vessel with liquid metal coolant and using water spray cooling on the guard vessel surface. The second part of the thesis presents examinations regarding an accelerator-driven system also cooled with Pb/Bi but with heat-exchangers located in the

Experimental study of rf pulsed heating

Directory of Open Access Journals (Sweden)

Lisa Laurent

2011-04-01

Full Text Available 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 10×10^{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.

Sauna exposure immediately prior to short-term heat acclimation accelerates phenotypic adaptation in females.

Science.gov (United States)

Mee, Jessica A; Peters, Sophie; Doust, Jonathan H; Maxwell, Neil S

2018-02-01

Investigate whether a sauna exposure prior to short-term heat acclimation (HA) accelerates phenotypic adaptation in females. Randomised, repeated measures, cross-over trial. Nine females performed two 5-d HA interventions (controlled hyperthermia T re ≥38.5°C), separated by 7-wk, during the follicular phase of the menstrual cycle confirmed by plasma concentrations of 17-β estradiol and progesterone. Prior to each 90-min HA session participants sat for 20-min in either a temperate environment (20°C, 40% RH; HA temp ) wearing shorts and sports bra or a hot environment (50°C, 30% RH) wearing a sauna suit to replicate sauna conditions (HA sauna ). Participants performed a running heat tolerance test (RHTT) 24-h pre and 24-h post HA. Mean heart rate (HR) (85±4 vs. 68±5 bpm, p≤0.001), sweat rate (0.4±0.2 vs. 0.0±0.0Lh -1 , p≤0.001), and thermal sensation (6±0 vs. 5±1, p=0.050) were higher during the sauna compared to temperate exposure. Resting rectal temperature (T re ) (-0.28±0.16°C), peak T re (-0.42±0.22°C), resting HR (-10±4 bpm), peak HR (-12±7 bpm), T re at sweating onset (-0.29±0.17°C) (p≤0.001), thermal sensation (-0.5±0.5; p=0.002), and perceived exertion (-3±2; p≤0.001) reduced during the RHTT, following HA sauna ; but not HA temp . Plasma volume expansion was greater following HA sauna (HA sauna , 9±7%; HA temp , 1±5%; p=0.013). Sweat rate (p≤0.001) increased and sweat NaCl (p=0.006) reduced during the RHTT following HA sauna and HA temp . This novel strategy initiated HA with an attenuation of thermoregulatory, cardiovascular, and perceptual strain in females due to a measurably greater strain in the sauna compared to temperate exposure when adopted prior to STHA. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Nb3Sn accelerator magnet development around the world

Energy Technology Data Exchange (ETDEWEB)

Michael J. Lamm

2003-06-23

During the past 30 years superconducting magnet systems have enabled accelerators to achieve energies and luminosities that would have been impractical if not impossible with resistive magnets. By far, NbTi has been the preferred conductor for this application because of its ductility and insensitivity of Jc to mechanical strain. This is despite the fact that Nb{sub 3}Sn has a more favorable Jc vs. B dependence and can operate at much higher temperatures. Unfortunately, NbTi conductor is reaching the limit of it usefulness for high field applications. Despite incremental increases in Jc and operation at superfluid temperatures, magnets are limited to approximately a 10 T field. Improvements in conductor performance combined with future requirements for accelerator magnets to have bore fields greater than 10 T or operate in areas of large beam-induced heat loads now make Nb{sub 3}Sn look attractive. Thus, laboratories in several countries are actively engaged in programs to develop Nb{sub 3}Sn accelerator magnets for future accelerator applications. A summary of this important research activity is presented along with a brief history of Nb{sub 3}Sn accelerator magnet development and a discussion of requirements for future accelerator magnets.

CFD Study of Deteriorated Turbulent Heat Transfer in Upward Flow

International Nuclear Information System (INIS)

Nietiadi, Yohanes Setiawan; Lee, Jeong Ik; Addad, Yacine

2014-01-01

DTHT regime can be induced by two effects: buoyancy and acceleration. Apart from these two deteriorating effects, another unique behavior of fluid in the DTHT regime is that the convective heat transfer rate will continue to deteriorate until it reaches certain point. The downstream of this point, is known as the recovery region, where the convective heat transfer rate returns back to the high values by recovering turbulence. We called this phenomena as re-turbulization.. The map of the DTHT regime can be seen from fig. 2, where the x-axis is the buoyancy parameter and y-axis is the acceleration parameter which is the agreed governing non-dimensional numbers among the researchers to illustrate the phenomena. The Buoyancy parameter is defind in Eq. (1) and the acceleration parameter is defined in Eq. (2), respectively. The threshold value for both effects to move from the forced turbulent heat transfer to the DTHT regime are found to be Bo* ≥ 2x10 -6 and Kv ≥ 2.5x10 -6 in the previous works. Bo * =Gr q /Re 3 '. 425 Pr 0 '. 8 (1). K v =4q + /Re (2). Many experiments and simulation have been done to investigate this phenomenon and the boundary of the regime. However, very limited number of experiment was conducted in the regime where buoyancy effect and acceleration effect are in the same order of magnitude and high enough to cause DTHT (mixed DTHT). Some important experimental researches that have been done in the gas DTHT regime is Lee et al. who investigated the heat transfer of gas flow in the range of buoyancy parameter from 3x10 -9 to 10 -5 and acceleration parameter span from 6x10 -8 to 5x10 -6 and presented the behavior of Nusselt number ratio from the experiment as fig. 3 and fig. 4. This paper will discuss a Computational Fluid Dynamics analysis on DTHT by assuming hypothetical boundary conditions especially on the mixed DTHT regime. It has been found that a gas cooled fast reactor has a tendency to operate in the Deteriorated Turbulent Heat

High-performance computing in accelerating structure design and analysis

International Nuclear Information System (INIS)

Li Zenghai; Folwell, Nathan; Ge Lixin; Guetz, Adam; Ivanov, Valentin; Kowalski, Marc; Lee, Lie-Quan; Ng, Cho-Kuen; Schussman, Greg; Stingelin, Lukas; Uplenchwar, Ravindra; Wolf, Michael; Xiao, Liling; Ko, Kwok

2006-01-01

Future high-energy accelerators such as the Next Linear Collider (NLC) will accelerate multi-bunch beams of high current and low emittance to obtain high luminosity, which put stringent requirements on the accelerating structures for efficiency and beam stability. While numerical modeling has been quite standard in accelerator R and D, designing the NLC accelerating structure required a new simulation capability because of the geometric complexity and level of accuracy involved. Under the US DOE Advanced Computing initiatives (first the Grand Challenge and now SciDAC), SLAC has developed a suite of electromagnetic codes based on unstructured grids and utilizing high-performance computing to provide an advanced tool for modeling structures at accuracies and scales previously not possible. This paper will discuss the code development and computational science research (e.g. domain decomposition, scalable eigensolvers, adaptive mesh refinement) that have enabled the large-scale simulations needed for meeting the computational challenges posed by the NLC as well as projects such as the PEP-II and RIA. Numerical results will be presented to show how high-performance computing has made a qualitative improvement in accelerator structure modeling for these accelerators, either at the component level (single cell optimization), or on the scale of an entire structure (beam heating and long-range wakefields)

Impact of variations of gravitational acceleration on the general circulation of the planetary atmosphere

Science.gov (United States)

Kilic, Cevahir; Raible, Christoph C.; Stocker, Thomas F.; Kirk, Edilbert

2017-01-01

Fundamental to the redistribution of energy in a planetary atmosphere is the general circulation and its meridional structure. We use a general circulation model of the atmosphere in an aquaplanet configuration with prescribed sea surface temperature and investigate the influence of the gravitational acceleration g on the structure of the circulation. For g =g0 = 9.81 ms-2 , three meridional cells exist in each hemisphere. Up to about g /g0 = 1.4 all cells increase in strength. Further increasing this ratio results in a weakening of the thermally indirect cell, such that a two- and finally a one-cell structure of the meridional circulation develops in each hemisphere. This transition is explained by the primary driver of the thermally direct Hadley cell: the diabatic heating at the equator which is proportional to g. The analysis of the energetics of the atmospheric circulation based on the Lorenz energy cycle supports this finding. For Earth-like gravitational accelerations transient eddies are primarily responsible for the meridional heat flux. For large gravitational accelerations, the direct zonal mean conversion of energy dominates the meridional heat flux.

Continuing studies of the plasma beat wave accelerator

International Nuclear Information System (INIS)

Joshi, C.

1990-01-01

This is a proposal for the release of third year funds for the ''Plasma Beat Wave Accelerator'' program (PBWA) at UCLA under the direction of Professor C. Joshi. This report is also a summary of progress on this project since March 1990; i.e., the date of the last report to the DOE. Once again we note that although the program is for historical reasons called the Plasma Beat Wave Accelerator Program, our group is active in all areas of applications of lasers and plasmas in future high energy accelerators. These are as follows: heat gradient plasma structures; excited by plasma beat wave technique; laser wake field technique; and plasma wake field technique. Development of a photoinjector-driven, 20 MeV linac; and theoretical studies of the plasma lens and use of plasmas at the final focus

Thermal and structural analysis of the LBL 10 x 40 cm long pulse accelerator and the 12 x 48 cm common long pulse accelerator for TFTR, doublet III-D, and MFTF-B

International Nuclear Information System (INIS)

Wells, R.P.

1985-11-01

Stress and deflection of the grid rails of the existing, Lawrence Berkeley Laboratory (LBL) designed, 10 x 40 cm Long Pulse (neutral beam) Accelerator (40LPA) and the expanded 12 x 48 cm version, Common Long Pulse Source (CLPS), have been computed for a series of assumed heat load distributions. The combined stress from self-constraint of thermal expansion and rail holder reaction forces has been calculated. A simplification of the gradient grid rail holder was analyzed and was found to work as well or better than the original 40LPA design under the most probable operating conditions. Heat flux non-uniformity over the rail surface for both accelerator designs was estimated from 40LPA grid calorimetry data for arc and beam extraction operation. The extrapolated total heat load per rail for the CLPS was less than the 1.2 kW value used in this analysis. Under worst case assumptions, the maximum equivalent stress in any of the molybdenum grid rails was less than 20% of yield. For the anticipated heat load distribution on the gradient grid, the predicted deflection of the grid rail meets the 0.0457 mm position tolerance except under extremely non-uniform heat loads

Thermal and structural analysis of the LBL 10 x 40 cm Long Pulse Accelerator and the 12 x 48 cm Common Long Pulse Accelerator for TFTR, Doublet III-D, and MFTF-B

International Nuclear Information System (INIS)

Wells, R.P.

1986-01-01

Stress and deflection of the grid rails of the existing, Lawrence Berkeley Laboratory (LBL) designed, 10 x 40 cm Long Pulse (neutral beam) Accelerator (40LPA) and the expanded 12 x 48 cm version, Common Long Pulse Source (CLPS), have been computed for a series of assumed heat load distributions. The combined stress from self-constraint of thermal expansion and rail holder reaction forces has been calculated. A simplification of the gradient grid rail holder was analyzed and was found to work as well or better than the original 40LPA design under the most probable operating conditions. Heat flux non-uniformity over the rail surface for both accelerator designs was estimated from 40LPA grid calorimetry data for arc and beam extraction operation. The extrapolated total heat load per rail for the CLPS was less than the 1.2 kW value used in this analysis. Under worst case assumptions, the maximum equivalent stress in any of the molybdenum grid rails was less than 20% of yield. For the anticipated heat load distribution on the gradient grid, the predicted deflection of the grid rail meets the 0.0457 mm position tolerant except under extremely non-uniform heat loads

Application of Plasma Waveguides to High Energy Accelerators

Energy Technology Data Exchange (ETDEWEB)

Milchberg, Howard M

2013-03-30

The eventual success of laser-plasma based acceleration schemes for high-energy particle physics will require the focusing and stable guiding of short intense laser pulses in reproducible plasma channels. For this goal to be realized, many scientific issues need to be addressed. These issues include an understanding of the basic physics of, and an exploration of various schemes for, plasma channel formation. In addition, the coupling of intense laser pulses to these channels and the stable propagation of pulses in the channels require study. Finally, new theoretical and computational tools need to be developed to aid in the design and analysis of experiments and future accelerators. Here we propose a 3-year renewal of our combined theoretical and experimental program on the applications of plasma waveguides to high-energy accelerators. During the past grant period we have made a number of significant advances in the science of laser-plasma based acceleration. We pioneered the development of clustered gases as a new highly efficient medium for plasma channel formation. Our contributions here include theoretical and experimental studies of the physics of cluster ionization, heating, explosion, and channel formation. We have demonstrated for the first time the generation of and guiding in a corrugated plasma waveguide. The fine structure demonstrated in these guides is only possible with cluster jet heating by lasers. The corrugated guide is a slow wave structure operable at arbitrarily high laser intensities, allowing direct laser acceleration, a process we have explored in detail with simulations. The development of these guides opens the possibility of direct laser acceleration, a true miniature analogue of the SLAC RF-based accelerator. Our theoretical studies during this period have also contributed to the further development of the simulation codes, Wake and QuickPIC, which can be used for both laser driven and beam driven plasma based acceleration schemes. We

Preparation and chemical crystallographic study of new hydrides and hydro-fluorides of ionic character; Preparation et etude cristallochimique de nouveaux hydrures et fluorohydrures a caractere ionique

Energy Technology Data Exchange (ETDEWEB)

Park, Hyung-Ho

1988-07-22

Within the context of a growing interest in the study of reversible hydrides with the perspective of their application in hydrogen storage, this research thesis more particularly addressed the case of ternary hydrides and fluorides, and of hydro-fluorides. The author reports the development of a method of preparation of alkaline hydrides, of alkaline earth hydrides and of europium hydride, and then the elaboration of ternary hydrides. He addresses the preparation of caesium fluorides and of calcium or nickel fluorides, of Europium fluorides, and of ternary fluorides. Then, he addresses the preparation of hydro-fluorides (caesium, calcium, europium fluorides, and caesium and nickel fluorides). The author presents the various experimental techniques: chemical analysis, radio-crystallographic analysis, volumetric mass density measurement, magnetic measurements, ionic conductivity measurements, Moessbauer spectroscopy, and nuclear magnetic resonance. He reports the crystallographic study of some ternary alkaline and alkaline-earth hydrides (KH-MgH{sub 2}, RbH-CaH{sub 2}, CsH-CaH{sub 2}, RbH-MgH{sub 2} and CsH-MgH{sub 2}) and of some hydro-fluorides (CsCaF{sub 2}H, EuF{sub 2}H, CsNiF{sub 2}H) [French] Dans une premiere partie, de nouveaux hydrures ternaires ont ete prepares et caracterises. Les systemes etudies sont AH-MH 2 (A = K, Rb, Cs et M = Mg, Ca). Dans les systemes AH-MgH 2 l'evolution structurale a ete discutee en fonction du caractere iono-covalent de la liaison magnesium-hydrogene. Dans une deuxieme partie, plusieurs nouveaux fluorohydrures ont ete mis en evidence. L'effet de la substitution de l'hydrogene au fluor dans ces phases a ete etudiee en utilisant la RMN, la spectroscopie Moessbauer, la conductivite ionique et les mesures magnetiques.

ELECTRON ACCELERATION BY MULTI-ISLAND COALESCENCE

International Nuclear Information System (INIS)

Oka, M.; Phan, T.-D.; Krucker, S.; Fujimoto, M.; Shinohara, I.

2010-01-01

Energetic electrons of up to tens of MeV are created during explosive phenomena in the solar corona. While many theoretical models consider magnetic reconnection as a possible way of generating energetic electrons, the precise roles of magnetic reconnection during acceleration and heating of electrons still remain unclear. Here, we show from two-dimensional particle-in-cell simulations that coalescence of magnetic islands that naturally form as a consequence of tearing mode instability and associated magnetic reconnection leads to efficient energization of electrons. The key process is the secondary magnetic reconnection at the merging points, or the 'anti-reconnection', which is, in a sense, driven by the converging outflows from the initial magnetic reconnection regions. By following the trajectories of the most energetic electrons, we found a variety of different acceleration mechanisms but the energization at the anti-reconnection is found to be the most important process. We discuss possible applications to the energetic electrons observed in the solar flares. We anticipate our results to be a starting point for more sophisticated models of particle acceleration during the explosive energy release phenomena.

Advanced heat pumps and their economic aspects. The case for super heat pump

International Nuclear Information System (INIS)

Yabe, Akira; Akiya, Takaji

1996-01-01

The results of the economic evaluation of the Super Heat Pump Energy Accumulation System project in Japan are reviewed. It is reported that although the initial costs of super heat pumps are higher than those of conventional systems, the calculated operating costs of a unit thermal energy produced by a super heat pump is reduced considerably. All the various system concepts with thermal/chemical storage were evaluated economically with the exception of the high temperature thermal storage systems using salt ammonia complexes and solvation. These latter systems were not further developed as pilot plants. It is advocated to accelerate the introduction of super heat pumps by facilitating their market introduction. Actual clathrate chemical storage systems have shown that the annual costs are comparable to those of an ice storage system. Clathrate systems will find their way in the market. It is concluded that most of the super heat pump systems and clathrate storage systems will be economic in the future. A big challenge however still exists in further improving the cost effectiveness of heat storage in tanks by reducing their size dramatically (to 1/10th)

Theory of factors limiting high gradient operation of warm accelerating structures

Energy Technology Data Exchange (ETDEWEB)

Nusinovich, Gregory S. [Univ. of Maryland, College Park, MD (United States)

2014-07-22

This report consists of two parts. In the first part we describe a study of the heating of microprotrusions on surfaces of accelerating structures. This ;process is believed to lead to breakdown in these structures. Our study revealed that for current accelerator parameters melting should not occur due to space charge limitations of the current emitted by a protrusion. The second part describes a novel concept to develop THz range sources based on harmonic cyclotron masers for driving future colliders. This work was stimulated by a recent request of SLAC to develop high power, high-efficiency sources of sub-THz radiation for future high-gradient accelerators.

Curing of bisphenol A-aniline based benzoxazine using phenolic, amino and mercapto accelerators

Directory of Open Access Journals (Sweden)

A. Rucigaj

2015-07-01

Full Text Available The curing of bisphenol A-aniline based benzoxazine was studied applying different accelerators (4,4'-thiodiphenol, o-dianisidine, 2-mercaptobenzimidazole and 4-mercaptophenol to initiate the catalytic ring-opening of benzoxazine. Possible pathways of benzoxazine ring-opening, polymerization and cross-linking without and with the addition of different accelerators are presented. The curing kinetics was investigated by model-free kinetic analysis of experimental data obtained by differential scanning calorimetry (DSC. The addition of different accelerators significantly reduced the onset temperature of curing in dynamic experiments. The effects of accelerators on the results of isothermal conversion prediction were studied and discussed in detail. Among the used accelerators, thiodiphenol showed the best accelerating efficiency and was consequently used in further studies, where its amount was varied. By low heating rate DSC analysis the catalytic ring-opening, thermally accelerated ring-opening and the diffusion-controlled steps were identified. The amount of added accelerator affected particularly the ring-opening and diffusion-controlled steps.

Advances of dense plasma physics with particle accelerators

Energy Technology Data Exchange (ETDEWEB)

Hoffmann, D.H.H.; Blazevic, A.; Rosmej, O.N.; Spiller, P.; Tahir, N.A.; Weyrich, K. [Gesellschaft fur Schwerionenforschung, GSI-Darmstadt, Plasmaphysik, Darmstadt (Germany); Hoffmann, D.H.H.; Dafni, T.; Kuster, M.; Roth, M.; Udrea, S.; Varentsov, D. [DarmstadtTechnische Univ., Institut fur Kernphysik (Germany); Jacoby, J. [Frankfurt Univ., Institut fur Angewandte Physik (Germany); Zioutas, K. [European Organization for Nuclear Research (CERN), Geneve (Switzerland); Patras Univ., Dept. of Physics (Greece); Sharkov, B.Y. [Institut for Theoretical and Experimental Physics ITEP, Moscow (Russian Federation)

2006-06-15

High intensity particle beams from accelerators induce high energy density states in bulk matter. The SIS-18 heavy ion synchrotron at GSI (Darmstadt, Germany) now routinely delivers intense Uranium beams that deposit about 1 kJ/g of specific energy in solid matter, e.g. solid lead. Due to the specific nature of the ion-matter interaction a volume of matter is heated uniformly with low gradients of temperature and pressure in the initial phase, depending on the pulse structure of the beam with respect to space and time. The new accelerator complex FAIR (Facility for Antiproton and ion Research) at GSI as well as beams from the CERN large hadron collider (LHC) will vastly extend the accessible parameter range for high energy density states. One special piece of accelerator equipment a superconducting high field dipole magnet, developed for the LHC at CERN is now serving as a key instrument to diagnose the dense plasma of the sun interior plasma, thus providing an extremely interesting combination of accelerator physics, plasma physics and particle physics. (authors)

Advances of dense plasma physics with particle accelerators

International Nuclear Information System (INIS)

Hoffmann, D.H.H.; Blazevic, A.; Rosmej, O.N.; Spiller, P.; Tahir, N.A.; Weyrich, K.; Hoffmann, D.H.H.; Dafni, T.; Kuster, M.; Roth, M.; Udrea, S.; Varentsov, D.; Jacoby, J.; Zioutas, K.; Sharkov, B.Y.

2006-01-01

High intensity particle beams from accelerators induce high energy density states in bulk matter. The SIS-18 heavy ion synchrotron at GSI (Darmstadt, Germany) now routinely delivers intense Uranium beams that deposit about 1 kJ/g of specific energy in solid matter, e.g. solid lead. Due to the specific nature of the ion-matter interaction a volume of matter is heated uniformly with low gradients of temperature and pressure in the initial phase, depending on the pulse structure of the beam with respect to space and time. The new accelerator complex FAIR (Facility for Antiproton and ion Research) at GSI as well as beams from the CERN large hadron collider (LHC) will vastly extend the accessible parameter range for high energy density states. One special piece of accelerator equipment a superconducting high field dipole magnet, developed for the LHC at CERN is now serving as a key instrument to diagnose the dense plasma of the sun interior plasma, thus providing an extremely interesting combination of accelerator physics, plasma physics and particle physics. (authors)

High efficiency, quasi-instantaneous steam expansion device utilizing fossil or nuclear fuel as the heat source

International Nuclear Information System (INIS)

Claudio Filippone

1999-01-01

Thermal-hydraulic analysis of a specially designed steam expansion device (heat cavity) was performed to prove the feasibility of steam expansions at elevated rates for power generation with higher efficiency. The steam expansion process inside the heat cavity greatly depends on the gap within which the steam expands and accelerates. This system can be seen as a miniaturized boiler integrated inside the expander where steam (or the proper fluid) is generated almost instantaneously prior to its expansion in the work-producing unit. Relatively cold water is pulsed inside the heat cavity, where the heat transferred causes the water to flash to steam, thereby increasing its specific volume by a large factor. The gap inside the heat cavity forms a special nozzle-shaped system in which the fluid expands rapidly, accelerating toward the system outlet. The expansion phenomenon is the cause of ever-increasing fluid speed inside the cavity system, eliminating the need for moving parts (pumps, valves, etc.). In fact, the subsequent velocity induced by the sudden fluid expansion causes turbulent conditions, forcing accelerating Reynolds and Nusselt numbers which, in turn, increase the convective heat transfer coefficient. When the combustion of fossil fuels constitutes the heat source, the heat cavity concept can be applied directly inside the stator of conventional turbines, thereby greatly increasing the overall system efficiency

Influencia de las mezclas de poliglucósido con tensioactivo aniónico en el lavado de tejido de poliéster

OpenAIRE

Carrión Fité, Francisco Javier

2006-01-01

Le développement remarquable des tensioactifs non ioniques en tant que composants dominants dans les formulations de lessive passe par la compréhension de leurs prestations pendant le lavage, non seulement pris séparément, mais aussi en tant que mélanges binaires contenant un tensioactif anionique. Pour obtenir de bons niveaux de biodégradabilité et de toxicité, les alkylpolyglucosides (APG) ont fait leur apparition sur le marché. Ces tensioactifs non ioniques, tirés de substances naturelles,...

Accelerator and Ion Beam Tradeoffs for Studies of Warm Dense Matter

International Nuclear Information System (INIS)

Barnard, J.J.; Briggs, R.J.; Callahan, D.A.; Davidson, R.C.; Friedman, A.; Grisham, L.; Lee, E.P.; Lee, R.W.; Logan, B.G.; Olson, C.L.; Rose, D.V.; Santhanam, P.; Sessler, A.M.; Staples, J.W.; Tabak, M.; Welch, D.R.; Wurtele, J.S.; Yu, S.S.

2006-01-01

One approach for heating a target to ''Warm Dense Matter'' conditions (similar, for example, to the interiors of giant planets or certain stages in inertial confinement fusion targets), is to use intense ion beams as the heating source (see refs.[6] and [7] and references therein for motivation and accelerator concepts). By consideration of ion beam phase-space constraints, both at the injector, and at the final focus, and consideration of simple equations of state and relations for ion stopping, approximate conditions at the target foil may be calculated. Thus, target temperature and pressure may be calculated as a function of ion mass, ion energy, pulse duration, velocity tilt, and other accelerator parameters. We connect some of these basic parameters to help search the extensive parameter space including ion mass, ion energy, total charge in beam pulse, beam emittance, target thickness and density

Electron Fermi acceleration in collapsing magnetic traps: Computational and analytical models

International Nuclear Information System (INIS)

Gisler, G.; Lemons, D.

1990-01-01

The authors consider the heating and acceleration of electrons trapped on magnetic field lines between approaching magnetic mirrors. Such a collapsing magnetic trap and consequent electron energization can occur whenever a curved (or straight) flux tube drifts into a relatively straight (or curved) perpendicular shock. The relativistic, three-dimensional, collisionless test particle simulations show that an initial thermal electron distribution is bulk heated while a few individual electrons are accelerated to many times their original energy before they escape the trap. Upstream field-aligned beams and downstream pancake distributions perpendicular to the field are predicted. In the appropriate limit the simulation results agree well with a nonrelativistic analytic model of the distribution of escaping electrons which is based on the first adiabatic invariant and energy conservation between collisions with the mirrors. Space science and astrophysical applications are discussed

Decay heat uncertainty quantification of MYRRHA

OpenAIRE

Fiorito Luca; Buss Oliver; Hoefer Axel; Stankovskiy Alexey; Eynde Gert Van den

2017-01-01

MYRRHA is a lead-bismuth cooled MOX-fueled accelerator driven system (ADS) currently in the design phase at SCK·CEN in Belgium. The correct evaluation of the decay heat and of its uncertainty level is very important for the safety demonstration of the reactor. In the first part of this work we assessed the decay heat released by the MYRRHA core using the ALEPH-2 burnup code. The second part of the study focused on the nuclear data uncertainty and covariance propagation to the MYRRHA decay hea...

Experimental study of an ion cyclotron instability in a magnetic well confined plasma; Etude experimentale d'une instabilite cyclotronique ionique dans un plasma confine dans un puits magnetique

Energy Technology Data Exchange (ETDEWEB)

Brossier, P [Commissariat a l' Energie Atomique, Fontenay-Aux-Roses (France). Centre d' Etudes Nucleaires

1969-07-01

This report is a contribution to the study of microinstabilities in macroscopically stable plasmas, in the low-{beta} limit. Ion cyclotron instabilities, with k{sub ||} = 0, have been numerically studied in detail; the computation of the density thresholds and growth rates of the different harmonics showed the relative role played by the following energy sources: density gradient, perpendicular distribution function and cold plasma component. This theoretical model has been compared with the results of a detailed study (density thresholds, wave structure, frequency spectrum, wavelengths, growth rate, amplitude of the electric field) of the instability observed in the DECA II device. This comparison gave a good agreement which shows the destabilising role played by the cold plasma component on a hot plasma with a loss cone distribution function. (author) [French] Ce rapport est une contribution a l'etude des microinstabilites dans les plasmas macroscopiquement stables, dans la limite des {beta} << 1. Les instabilites cyclotroniques ioniques, a k{sub ||} = 0, ont ete etudiees numeriquement en detail; le calcul des seuils de densite et taux de croissance des differents harmoniques a permis de preciser l'importance relative des facteurs destabilisants suivants: gradient de densite, fonction de distribution perpendiculaire, presence de plasma froid. Ce modele theorique a ete confronte avec les resultats d'une etude detaillee (seuils de densite, structure de l'onde, spectres de frequence, longueurs d'onde, taux de croissance, amplitude du champ electrique) de l'instabilite observee dans l'experience DECA II, Cette confrontation aboutit a un accord satisfaisant qui montre le role destabilisant joue par le plasma froid sur un plasma chaud presentant une distribution de cone de pertes. (auteur)

In situ baking method for degassing of a kicker magnet in accelerator beam line

International Nuclear Information System (INIS)

Kamiya, Junichiro; Ogiwara, Norio; Yanagibashi, Toru; Kinsho, Michikazu; Yasuda, Yuichi

2016-01-01

In this study, the authors propose a new in situ degassing method by which only kicker magnets in the accelerator beam line are baked out without raising the temperature of the vacuum chamber to prevent unwanted thermal expansion of the chamber. By simply installing the heater and thermal radiation shield plates between the kicker magnet and the chamber wall, most of the heat flux from the heater directs toward the kicker magnet. The result of the verification test showed that each part of the kicker magnet was heated to above the target temperature with a small rise in the vacuum chamber temperature. A graphite heater was selected in this application to bake-out the kicker magnet in the beam line to ensure reliability and easy maintainability of the heater. The vacuum characteristics of graphite were suitable for heater operation in the beam line. A preliminary heat-up test conducted in the accelerator beam line also showed that each part of the kicker magnet was successfully heated and that thermal expansion of the chamber was negligibly small

In situ baking method for degassing of a kicker magnet in accelerator beam line

Energy Technology Data Exchange (ETDEWEB)

Kamiya, Junichiro, E-mail: kamiya.junichiro@jaea.go.jp; Ogiwara, Norio; Yanagibashi, Toru; Kinsho, Michikazu [Japan Atomic Energy Agency, J-PARC Center, Ooaza Shirakata 2-4, Tokai, Naka, Ibaraki 319-1195 (Japan); Yasuda, Yuichi [SAKAGUCHI E.H VOC CORP., Sakura Dai-san Kogyodanchi 1-8-6, Osaku, Sakura, Chiba 285-0802 (Japan)

2016-03-15

In this study, the authors propose a new in situ degassing method by which only kicker magnets in the accelerator beam line are baked out without raising the temperature of the vacuum chamber to prevent unwanted thermal expansion of the chamber. By simply installing the heater and thermal radiation shield plates between the kicker magnet and the chamber wall, most of the heat flux from the heater directs toward the kicker magnet. The result of the verification test showed that each part of the kicker magnet was heated to above the target temperature with a small rise in the vacuum chamber temperature. A graphite heater was selected in this application to bake-out the kicker magnet in the beam line to ensure reliability and easy maintainability of the heater. The vacuum characteristics of graphite were suitable for heater operation in the beam line. A preliminary heat-up test conducted in the accelerator beam line also showed that each part of the kicker magnet was successfully heated and that thermal expansion of the chamber was negligibly small.

Gyrokinetic electron acceleration in the force-free corona with anomalous resistivity

OpenAIRE

Arzner, Kaspar; Vlahos, Loukas

2006-01-01

We numerically explore electron acceleration and coronal heating by dissipative electric fields. Electrons are traced in linear force-free magnetic fields extrapolated from SOHO/MDI magnetograms, endowed with anomalous resistivity ($\\eta$) in localized dissipation regions where the magnetic twist $\

Heat transfer effects on flow past an exponentially accelerated vertical plate with variable temperature

Directory of Open Access Journals (Sweden)

Muthucumaraswamy R.

2008-01-01

Full Text Available An exact solution to the problem of flow past an exponentially accelerated infinite vertical plate with variable temperature is analyzed. The temperature of the plate is raised linearly with time t. The dimensionless governing equations are solved using Laplace-transform technique. The velocity and temperature profiles are studied for different physical parameters like thermal Grashof number Gr, time and an accelerating parameter a. It is observed that the velocity increases with increasing values of a or Gr.

Potential Remedies for the High Synchrotron-Radiation-Induced Heat Load for Future Highest-Energy-Proton Circular Colliders

CERN Document Server

AUTHOR|(CDS)2084568; Baglin, Vincent; Schaefers, Franz

2015-01-01

We propose a new method for handling the high synchrotron radiation (SR) induced heat load of future circular hadron colliders (like FCC-hh). FCC-hh are dominated by the production of SR, which causes a significant heat load on the accelerator walls. Removal of such a heat load in the cold part of the machine, as done in the Large Hadron Collider, will require more than 100 MW of electrical power and a major cooling system. We studied a totally different approach, identifying an accelerator beam screen whose illuminated surface is able to forward reflect most of the photons impinging onto it. Such a reflecting beam screen will transport a significant part of this heat load outside the cold dipoles. Then, in room temperature sections, it could be more efficiently dissipated. Here we will analyze the proposed solution and address its full compatibility with all other aspects an accelerator beam screen must fulfill to keep under control beam instabilities as caused by electron cloud formation, impedance, dynamic...

Essay: Robert H. Siemann As Leader of the Advanced Accelerator Research Department

Energy Technology Data Exchange (ETDEWEB)

Colby, Eric R.; Hogan, Mark J.; /SLAC

2011-11-14

Robert H. Siemann originally conceived of the Advanced Accelerator Research Department (AARD) as an academic, experimental group dedicated to probing the technical limitations of accelerators while providing excellent educational opportunities for young scientists. The early years of the Accelerator Research Department B, as it was then known, were dedicated to a wealth of mostly student-led experiments to examine the promise of advanced accelerator techniques. High-gradient techniques including millimeter-wave rf acceleration, beam-driven plasma acceleration, and direct laser acceleration were pursued, including tests of materials under rf pulsed heating and short-pulse laser radiation, to establish the ultimate limitations on gradient. As the department and program grew, so did the motivation to found an accelerator research center that brought experimentalists together in a test facility environment to conduct a broad range of experiments. The Final Focus Test Beam and later the Next Linear Collider Test Accelerator provided unique experimental facilities for AARD staff and collaborators to carry out advanced accelerator experiments. Throughout the evolution of this dynamic program, Bob maintained a department atmosphere and culture more reminiscent of a university research group than a national laboratory department. His exceptional ability to balance multiple roles as scientist, professor, and administrator enabled the creation and preservation of an environment that fostered technical innovation and scholarship.

Essay: Robert H. Siemann As Leader of the Advanced Accelerator Research Department

International Nuclear Information System (INIS)

Colby, Eric R.; Hogan, Mark J.

2008-01-01

Robert H. Siemann originally conceived of the Advanced Accelerator Research Department (AARD) as an academic, experimental group dedicated to probing the technical limitations of accelerators while providing excellent educational opportunities for young scientists. The early years of the Accelerator Research Department B, as it was then known, were dedicated to a wealth of mostly student-led experiments to examine the promise of advanced accelerator techniques. High-gradient techniques including millimeter-wave rf acceleration, beam-driven plasma acceleration, and direct laser acceleration were pursued, including tests of materials under rf pulsed heating and short-pulse laser radiation, to establish the ultimate limitations on gradient. As the department and program grew, so did the motivation to found an accelerator research center that brought experimentalists together in a test facility environment to conduct a broad range of experiments. The Final Focus Test Beam and later the Next Linear Collider Test Accelerator provided unique experimental facilities for AARD staff and collaborators to carry out advanced accelerator experiments. Throughout the evolution of this dynamic program, Bob maintained a department atmosphere and culture more reminiscent of a university research group than a national laboratory department. His exceptional ability to balance multiple roles as scientist, professor, and administrator enabled the creation and preservation of an environment that fostered technical innovation and scholarship.

Free convection film flows and heat transfer laminar free convection of phase flows and models for heat-transfer analysis

CERN Document Server

Shang, De-Yi

2012-01-01

This book presents recent developments in our systematic studies of hydrodynamics and heat and mass transfer in laminar free convection, accelerating film boiling and condensation of Newtonian fluids, as well as accelerating film flow of non-Newtonian power-law fluids (FFNF). These new developments provided in this book are (i) novel system of analysis models based on the developed New Similarity Analysis Method; (ii) a system of advanced methods for treatment of gas temperature- dependent physical properties, and liquid temperature- dependent physical properties; (iii) the organically combined models of the governing mathematical models with those on treatment model of variable physical properties; (iv) rigorous approach of overcoming a challenge on accurate solution of three-point boundary value problem related to two-phase film boiling and condensation; and (v) A pseudo-similarity method of dealing with thermal boundary layer of FFNF for greatly simplifies the heat-transfer analysis and numerical calculati...

Electron Currents and Heating in the Ion Diffusion Region of Asymmetric Reconnection

Science.gov (United States)

Graham, D. B.; Khotyaintsev, Yu. V.; Norgren, C.; Vaivads, A.; Andre, M.; Lindqvist, P. A.; Marklund, G. T.; Ergun, R. E.; Paterson, W. R.; Gershman, D. J.;

Heat transfer analysis of frictional heat dissipation during articulation of femoral implants.

Science.gov (United States)

Davidson, J A; Gir, S; Paul, J P

1988-12-01

Previous studies have shown the tendency for frictional heating to occur during articulation of total hip systems in vitro under simulated hip loading conditions. The magnitude of this heating is sufficient to accelerate wear, creep, and oxidation degradation of the UHMWPE bearing surface. It was shown that ceramic articulating systems generate less frictional heating than polished cobalt alloy against UHMWPE. This frictional heating is expected to occur primarily for younger, heavier, and more active patients. Thus, long-term performance of the articulating hip system in these patients may not be that predicted from current, body-temperature wear, creep, and degradation studies. Although the tendency to generate frictional heat has been observed only during in vitro simulated hip loading, a heat transfer analysis of this phenomenon is presented to evaluate the ability of the hip joint to dissipate such heating in vivo. Additional experiments were performed using controlled resistance heaters inside a cobalt femoral head to verify the calculated levels of frictional heat and to assess the heat dissipation under simulated in vivo conditions. The effect of blood perfusion on the effective thermal conductivity of the joint capsule is also discussed. The present study describes and analyzes the various heat dissipation mechanisms present both in vitro and in vivo during articulation of metal and ceramic hip systems. From these tests and analyses, it is concluded that frictional heating in the reconstructed hip cannot be effectively removed, and that degredative elevated temperature processes can be expected to occur in vivo to both the UHMWPE and adjacent tissue under extended periods of excessive patient activity. This is particularly true for metal cobalt alloy femoral heads articulating on UHMWPE versus ceramic heads which generate significantly lower levels of heat.

Two-dimensional heat conducting simulation of plasma armatures

International Nuclear Information System (INIS)

Huerta, M.A.; Boynton, G.

1991-01-01

This paper reports on our development of a two-dimensional MHD code to simulate internal motions in a railgun plasma armature. The authors use the equations of resistive MHD, with Ohmic heating, and radiation heat transport. The authors use a Flux Corrected Transport code to advance all quantities in time. Our runs show the development of complex flows, subsequent shedding of secondary arcs, and a drop in the acceleration of the armature

CELLS OVEREXPRESSING HSP27 SHOW ACCELERATED RECOVERY FROM HEAT-INDUCED NUCLEAR-PROTEIN AGGREGATION

NARCIS (Netherlands)

KAMPINGA, HH; BRUNSTING, JF; STEGE, GJJ; KONINGS, AWT; LANDRY, J

1994-01-01

Protein denaturation/aggregation upon cell exposure to heat shock is a likely cause of cell death. in the nucleus, protein aggregation has often been correlated to inhibition of nuclear located processes and heat-induced cell killing. in Chinese hamster 023 cells made thermotolerant by a prior

Heat transfer of rarefied gases on tube bundles in crossflow

International Nuclear Information System (INIS)

Hannemann, H.

1976-01-01

A helium refrigeration plant, serving to cool superconducting high-frequency resonators of a linear accelerator, generates temperatures of 1.8 K at a pressure of 16.6 mbar. The helium, becoming gaseous after release of the heat of vaporization, will be heated up to room temperature in several heat exchangers in the further course of the process. Because of the pressure losses in the heat exchangers, the pressure of the helium will be reduced to 12 mbar. In the present paper, design equations with respect to heat transfer and pressure loss will be derived for the heat exchangers which will be used in similar for generating still lower temperatures at still lower pressures. (orig./RW) [de

Toward a Heat Recovery Chimney

Directory of Open Access Journals (Sweden)

Min Pan

2011-11-01

Full Text Available The worldwide population increase and subsequent surge in energy demand leads electricity producers to increase supply in an attempt to generate larger profit margins. However, with Global Climate Change becoming a greater focus in engineering, it is critical for energy to be converted in as environmentally benign a way as possible. There are different sustainable methods to meet the energy demand. However, the focus of this research is in the area of Waste Heat Recovery. The waste heat stored in the exiting condenser cooling water is delivered to the air flow through a water-air cross flow heat exchanger. A converging thermal chimney structure is then applied to increase the velocity of the airflow. The accelerated air can be used to turn on the turbine-generator installed on the top the thermal chimney so that electricity can be generated. This system is effective in generating electricity from otherwise wasted heat.

Advanced turbine/CO2 pellet accelerator

International Nuclear Information System (INIS)

Foster, C.A.; Fisher, P.W.

1994-01-01

An advanced turbine/CO 2 pellet accelerator is being evaluated as a depaint technology at Oak Ridge National Laboratory. The program, sponsored by Warner Robins Air Logistics Center, Robins Air Force Base, Georgia, has developed a robot-compatible apparatus that efficiently accelerates pellets of dry ice with a high-speed rotating wheel. In comparison to the more conventional compressed air sandblast pellet accelerators, the turbine system can achieve higher pellet speeds, has precise speed control, and is more than ten times as efficient. A preliminary study of the apparatus as a depaint technology has been undertaken. Depaint rates of military epoxy/urethane paint systems on 2024 and 7075 aluminum panels as a function of pellet speed and throughput have been measured. In addition, methods of enhancing the strip rate by combining infra-red heat lamps with pellet blasting have also been studied. The design and operation of the apparatus will be discussed along with data obtained from the depaint studies. Applications include removal of epoxy-based points from aircraft and the cleaning of surfaces contaminated with toxic, hazardous, or radioactive substances. The lack of a secondary contaminated waste stream is of great benefit

Accelerator and Fusion Research Division: summary of activities, 1983

International Nuclear Information System (INIS)

1984-08-01

The activities described in this summary of the Accelerator and Fusion Research Division are diverse, yet united by a common theme: it is our purpose to explore technologically advanced techniques for the production, acceleration, or transport of high-energy beams. These beams may be the heavy ions of interest in nuclear science, medical research, and heavy-ion inertial-confinement fusion; they may be beams of deuterium and hydrogen atoms, used to heat and confine plasmas in magnetic fusion experiments; they may be ultrahigh-energy protons for the next high-energy hadron collider; or they may be high-brilliance, highly coherent, picosecond pulses of synchrotron radiation

Profiles of fast ions that are accelerated by high harmonic fast waves in the National Spherical Torus Experiment

International Nuclear Information System (INIS)

Liu, D; Heidbrink, W W; Podesta, M; Ruskov, E; Bell, R E; Fredrickson, E D; Medley, S S; Harvey, R W

2010-01-01

Combined neutral beam injection and high-harmonic fast-wave (HHFW) heating accelerate deuterium fast ions in the National Spherical Torus Experiment (NSTX). With 1.1 MW of HHFW power, the neutron emission rate is about three times larger than in the comparison discharge without HHFW heating. Acceleration of fast ions above the beam injection energy is evident on an E||B type neutral particle analyzer (NPA), a 4-chord solid state neutral particle analyzer (SSNPA) array and a 16-channel fast-ion D-alpha (FIDA) diagnostic. The accelerated fast ions observed by the NPA and SSNPA diagnostics mainly come from passive charge exchange reactions at the edge due to the NPA/SSNPA localization in phase space. The spatial profile of accelerated fast ions that is measured by the FIDA diagnostic is much broader than in conventional tokamaks because of the multiple resonance layers and large orbits in NSTX. The fast-ion distribution function calculated by the CQL3D Fokker-Planck code differs from the measured spatial profile, presumably because the current version of CQL3D uses a zero-banana-width model. In addition, compressional Alfven eigenmode activity is stronger during the HHFW heating and it may affect the fast-ion spatial profile.

Heat shock protein (Hsp) 40 mutants inhibit Hsp70 in mammalian cells

NARCIS (Netherlands)

Michels, AA; Kanon, B; Bensaude, O; Kampinga, HH

1999-01-01

Heat shock protein (Hsp) 70 and Hsp40 expressed in mammalian cells had been previously shown to cooperate in accelerating the reactivation of heat-denatured firefly luciferase (Michels, A. A., Kanon, B., Konings, A. W. T., Ohtsuka, K,, Bensaude, O., and Kampinga, H. H. (1997) J. Biol. Chem. 272,

Electron acceleration by wave turbulence in a magnetized plasma

Science.gov (United States)

Rigby, A.; Cruz, F.; Albertazzi, B.; Bamford, R.; Bell, A. R.; Cross, J. E.; Fraschetti, F.; Graham, P.; Hara, Y.; Kozlowski, P. M.; Kuramitsu, Y.; Lamb, D. Q.; Lebedev, S.; Marques, J. R.; Miniati, F.; Morita, T.; Oliver, M.; Reville, B.; Sakawa, Y.; Sarkar, S.; Spindloe, C.; Trines, R.; Tzeferacos, P.; Silva, L. O.; Bingham, R.; Koenig, M.; Gregori, G.

2018-05-01

Astrophysical shocks are commonly revealed by the non-thermal emission of energetic electrons accelerated in situ1-3. Strong shocks are expected to accelerate particles to very high energies4-6; however, they require a source of particles with velocities fast enough to permit multiple shock crossings. While the resulting diffusive shock acceleration4 process can account for observations, the kinetic physics regulating the continuous injection of non-thermal particles is not well understood. Indeed, this injection problem is particularly acute for electrons, which rely on high-frequency plasma fluctuations to raise them above the thermal pool7,8. Here we show, using laboratory laser-produced shock experiments, that, in the presence of a strong magnetic field, significant electron pre-heating is achieved. We demonstrate that the key mechanism in producing these energetic electrons is through the generation of lower-hybrid turbulence via shock-reflected ions. Our experimental results are analogous to many astrophysical systems, including the interaction of a comet with the solar wind9, a setting where electron acceleration via lower-hybrid waves is possible.

Particle acceleration by electromagnetic ion cyclotron turbulence

International Nuclear Information System (INIS)

Crew, G.B.; Chang, Tom

1990-01-01

The LF EM-turbulence which furnishes energy for the acceleration of ions in various regions of the earth's magnetosphere efficiently accomplishes its transfer of energy from waves to particles through ion cyclotron resonance (ICR) with the left-hand polarized component of the turbulence; the result of this interaction is a heating of the particle distribution. A general theoretical treatment of ICR heating in a weakly inhomogeneous magnetic geometry is presented, en route to a more detailed examination of auroral ion conics' formation. A substantial simplification of the analysis of the altitude-asymptotic form of the conic distribution is obtained via the similarity transformation introduced into the properties of the electric field spectral density and the earth's dipolar magnetic field. 60 refs

Thermo-structural analysis of the rf-induced pulsed surface heating of the CLIC accelerating structures

CERN Document Server

Huopana, Jouni Juhani

2006-01-01

The CLIC (Compact LInear Collider) is being studied at CERN as a potential multi-TeV e+e- collider. The acceleration of the particles is done by RF (Radio Frequency). The surfaces of the RF (radio frequency) accelerating cavities are exposed to high pulsed RF currents which induce cyclic thermal stresses. These cyclic stresses are crucial for the fatigue lifetime of the cavities. To study the fatigue phenomenon properly the induced stresses must be well known. ANSYS FEM simulations were made to study the thermo-structural behaviour of the CLIC accelerating structure in copper zirconium, bimetallic and diamond coated constructions. The simulations showed the existence of high thermal stresses and low stress level shockwaves. It was also shown that the bimetallic structure increases stress values due to the differences in material properties. Diamond coating was found to reduce the thermal stresses.

Microwave Accelerated Polymerization of 2-Phenyl-2-Oxazoline: Microwave or Temperature Effects?

NARCIS (Netherlands)

Hoogenboom, R.; Leenen, M.A.M.; Wiesbrock, F.D.; Schubert, U.S.

2005-01-01

Summary: Investigations regarding the cationic ring-opening polymerization of 2-phenyl-2-oxazoline under microwave irradiation and conventional heating are reported. This study was inspired by contradictory reports of the (non-)existence of non-thermal microwave effects that might accelerate the

Vacuum system of tandem type electrostatic accelerator of Kyushu University

International Nuclear Information System (INIS)

Nakajima, Yutaka

1981-01-01

In the tandem type electrostatic accelerator of Kyushu University, the problem of vacuum in the beam transport system including the accelerator tube has been considered as one of the important elements for the performance of the electrostatic accelerator from the beginning of construction. Though the three-stage tandem accelerating scheme was considered as the beam transport system at the beginning of the program, in which the existing 6 MV Van de Graaf accelerator was to be used as the injector, three types of ion sources are prepared at present; the sputter ion source to generate negative heavy ions, the polarizing ion source to generate negative polarized protons or deuterons, and direct extraction type negative ion source. Ultrahigh evacuating system, in which the sputter ion pump is mainly employed, and the turbo-molecular pump is used supplementarily, was installed in the vacuum system. The vacuum of approximately 10 - 9 Torr level off-beam at the inlet or outlet of the accelerator tube and approximately 10 - 8 Torr level in the tubing section in the center terminal were achieved. Since the upper limit of withstand voltage of the accelerating tube was not able to be satisfied for the insufficient baking at the beginning, it was finally decided that the accelerating tube should be heated by directly supplying power to the electrode through low voltage discharge in the tube. This method enabled the generated voltage at the terminal to exceed 10 MV. (Wakatsuki, Y.)

DEVELOPING THE PHYSICS DESIGN FOR NDCX-II, A UNIQUE PULSE-COMPRESSING ION ACCELERATOR

International Nuclear Information System (INIS)

Friedman, A.; Barnard, J.J.; Cohen, R.H.; Grote, D.P.; Lund, S.M.; Sharp, W.M.; Faltens, A.; Henestroza, E.; Jung, J.-Y.; Kwan, J.W.; Lee, E.P.; Leitner, M.A.; Logan, B.G.; Vay, J.-L.; Waldron, W.L.; Davidson, R.C.; Dorf, M.; Gilson, E.P.; Kaganovich, I.

2009-01-01

The Heavy Ion Fusion Science Virtual National Laboratory (a collaboration of LBNL, LLNL, and PPPL) is using intense ion beams to heat thin foils to the 'warm dense matter' regime at ∼ + ions to ∼1 ns while accelerating it to 3-4 MeV over ∼15 m. Strong space charge forces are incorporated into the machine design at a fundamental level. We are using analysis, an interactive 1D PIC code (ASP) with optimizing capabilities and centroid tracking, and multi-dimensional Warpcode PIC simulations, to develop the NDCX-II accelerator. This paper describes the computational models employed, and the resulting physics design for the accelerator.

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

International Nuclear Information System (INIS)

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

1994-01-01

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

Economics and the question of low-grade heat

International Nuclear Information System (INIS)

Gorbet, F.W.

1976-01-01

This paper examines, from the viewpoint of an economist, the issues involved in the increased waste heat production generated by the rapid acceleration of electrical production and nuclear generation. It reviews some of the literature on low-grade heat - its economic considerations and ecological impact - and examines the applicability of the traditional type of analytical decision tool (cost/benefit analysis) to the efficient design of heat rejection systems. It is recognized that decisions should be made on the basis of social costs and benefits as well as purely monetary considerations. The validity and shortcomings of cost/benefit analysis are presented. It is concluded that, for energy policy planning and waste heat management, economic feasibility studies should lay out the options together with the costs and risks. (author)

Plasma heating in a variable magnetic field

Energy Technology Data Exchange (ETDEWEB)

Kichigin, G. N., E-mail: king@iszf.irk.ru [Russian Academy of Sciences, Institute of Solar-Terrestrial Physics (Russian Federation)

2013-05-15

The problem of particle acceleration in a periodically variable magnetic field that either takes a zero value or passes through zero is considered. It is shown that, each time the field [0]passes through zero, the particle energy increases abruptly. This process can be regarded as heating in the course of which plasma particles acquire significant energy within one field period. This mechanism of plasma heating takes place in the absence of collisions between plasma particles and is analogous to the mechanism of magnetic pumping in collisional plasma considered by Alfven.

Current and future industrial application of electron accelerators in Thailand

International Nuclear Information System (INIS)

Siri-Upathum, Chyagrit

2003-01-01

Industrial applications of electron accelerators in Thailand, first introduced in 1997 for radiation sterilized products such as doctor gown, pampas, feminine napkin etc followed by installation of accelerators, one with energies at 20 MV and the other at 5 MV to produce new value added products like gem stones, topaz, tourmaline and zircon. The machines operate in pulse mode and is also used for irradiation services for food and sterilized products treatment. The need for low and medium energy accelerators in radiation technology is stressed. They are to be used for crosslinking of electrical wire and cable, heat shrinkable materials, low protein concentrated rubber latex, rubber wood furniture and parts, and silk protein degradation. The role of governmental organizations like Nuclear Research Institute (OAEP) and universities in stimulating the utilization of radiation processing in Thailand is strengthened. (S. Ohno)

Current and future industrial application of electron accelerators in Thailand

Energy Technology Data Exchange (ETDEWEB)

Siri-Upathum, Chyagrit [Chulalongkorn Univ., Faculty of Engineering, Bangkok (Thailand)

2003-02-01

Industrial applications of electron accelerators in Thailand, first introduced in 1997 for radiation sterilized products such as doctor gown, pampas, feminine napkin etc followed by installation of accelerators, one with energies at 20 MV and the other at 5 MV to produce new value added products like gem stones, topaz, tourmaline and zircon. The machines operate in pulse mode and is also used for irradiation services for food and sterilized products treatment. The need for low and medium energy accelerators in radiation technology is stressed. They are to be used for crosslinking of electrical wire and cable, heat shrinkable materials, low protein concentrated rubber latex, rubber wood furniture and parts, and silk protein degradation. The role of governmental organizations like Nuclear Research Institute (OAEP) and universities in stimulating the utilization of radiation processing in Thailand is strengthened. (S. Ohno)

Characteristics of Vacuum Freeze Drying with Utilization of Internal Cooling and Condenser Waste Heat for Sublimation

Directory of Open Access Journals (Sweden)

Muhammad Alhamid

2013-09-01

Full Text Available Vacuum freeze drying is an excellent drying method, but it is very energy-intensive because a relatively long drying time is required. This research investigates the utilization of condenser waste heat for sublimation as a way of accelerating the drying rate. In addition, it also investigates the effect of internal cooling combined with vacuum cooling in the pressure reduction process. Jelly fish tentacles were used as the specimen, with different configurations for condenser heat waste and internal cooling valve opening. The results show that heating with condenser heat waste can accelerate the drying rate up to 0.0035 kg/m2.s. In addition, pre-freezing by internal cooling prevents evaporation until the mass of the specimen is 0.47 g and promotes transition of the specimen into the solid phase.

Stochastic heating in the cyclotron resonance of electrons

International Nuclear Information System (INIS)

Gutierrez T, C.; Hernandez A, O.

1999-01-01

The study of the different schemes of plasma heating by radiofrequency waves is a very actual problem related with the plasma heating in different machines and the particle acceleration mechanisms. In this work, it is obtained the expression for the temporal evolution of the energy absorbed in the cyclotron resonance of electrons where it is showed the stochastic character of the energy absorption. It is obtained the stochastic criteria in a magnetic configuration of an Ecr type plasma source. (Author)

Une plate-forme sans fil pour electrochimique spectroscopie d'impédance

OpenAIRE

Ghaffari, Seyed Alireza

2015-01-01

Avec l’émergence soutenue de capteurs et de dispositifs électrochimiques innovants, la spectroscopie d'impédance électrochimique est devenue l'un des outils les plus importants pour la caractérisation et la modélisation de la matière ionique et de l'interfaçage des capteurs. La capacité de détecter automatiquement, à l’aide de dispositifs électrochimiques peu couteux, les caractéristiques physiques et chimiques de la matière ionique ouvre une gamme d’application très variée pour la compréhens...

Bayesian analysis of heat pipe life test data for reliability demonstration testing

International Nuclear Information System (INIS)

Bartholomew, R.J.; Martz, H.F.

1985-01-01

The demonstration testing duration requirements to establish a quantitative measure of assurance of expected lifetime for heat pipes was determined. The heat pipes are candidate devices for transporting heat generated in a nuclear reactor core to thermoelectric converters for use as a space-based electric power plant. A Bayesian analysis technique is employed, utilizing a limited Delphi survey, and a geometric mean accelerated test criterion involving heat pipe power (P) and temperature (T). Resulting calculations indicate considerable test savings can be achieved by employing the method, but development testing to determine heat pipe failure mechanisms should not be circumvented

Direct high-temperature ohmic heating of metals as liquid pipes.

Science.gov (United States)

Grosse, A V; Cahill, J A; Liddell, W L; Murphy, W J; Stokes, C S

1968-05-03

When a sufficiently high electric current is passed through a liquid metal, the electromagnetic pressure pinches off the liquid metal and interrupts the flow of current. For the first time the pinch effect has been overcome by use of centrifugal acceleration. By rotation of a pipe of liquid metal, tin or bismuth or their alloys, at sufficiently high speed, it can be heated electrically without intermission of the electric current. One may now heat liquid metallic substances, by resistive (ohmic) heating, to 5000 degrees K and perhaps higher temperatures.

Accelerator-Driven Thorium Cycle: New Technology Makes It Feasible

International Nuclear Information System (INIS)

Adams, Marvin; Best, Fred; Kurwitz, Cable; McInturff, Al; McIntyre, Peter; Rogers, Bob; Sattarov, Akhdior; Wu Zeyun; Yavuz, Mustafa; Meitzler, Charles

2002-01-01

We have developed a conceptual design for an accelerator-driven thorium cycle power reactor which addresses the issues of accelerator performance, reliability, and neutronics that limited earlier designs. The proton drive beam is provided by a flux-coupled stack of isochronous cyclotrons, occupying the same footprint as a single cyclotron but providing 7 independent beams from 7 separate accelerating structures within a common magnetic envelope. The core is arranged in a hexagonal lattice, and the 7 beams are used to provide a hexagonal drive beam pattern so that the effective neutron gain is relatively uniform over the entire core volume. Reliability is achieved by redundancy: if any drive beam is interrupted, the other 6 suffice to maintain reactor operation. A new approach to fuel cladding should make it possible to operate with lead moderator at temperatures ∼ 800 C, enabling access to advanced heat cycles and perhaps to a Brayton cycle for hydrogen production. (authors)

Genomic Selection Improves Heat Tolerance in Dairy Cattle

Science.gov (United States)

Garner, J. B.; Douglas, M. L.; Williams, S. R. O; Wales, W. J.; Marett, L. C.; Nguyen, T. T. T.; Reich, C. M.; Hayes, B. J.

2016-01-01

Dairy products are a key source of valuable proteins and fats for many millions of people worldwide. Dairy cattle are highly susceptible to heat-stress induced decline in milk production, and as the frequency and duration of heat-stress events increases, the long term security of nutrition from dairy products is threatened. Identification of dairy cattle more tolerant of heat stress conditions would be an important progression towards breeding better adapted dairy herds to future climates. Breeding for heat tolerance could be accelerated with genomic selection, using genome wide DNA markers that predict tolerance to heat stress. Here we demonstrate the value of genomic predictions for heat tolerance in cohorts of Holstein cows predicted to be heat tolerant and heat susceptible using controlled-climate chambers simulating a moderate heatwave event. Not only was the heat challenge stimulated decline in milk production less in cows genomically predicted to be heat-tolerant, physiological indicators such as rectal and intra-vaginal temperatures had reduced increases over the 4 day heat challenge. This demonstrates that genomic selection for heat tolerance in dairy cattle is a step towards securing a valuable source of nutrition and improving animal welfare facing a future with predicted increases in heat stress events. PMID:27682591

Selenide isotope generator for the Galileo Mission: copper/water axially-grooved heat pipe topical report

International Nuclear Information System (INIS)

Strazza, N.P.

1979-01-01

This report presents a summary of the major accomplishments for the development, fabrication, and testing of axially-grooved copper/water heat pipes for Selenide Isotopic Generator (SIG) applications. The early development consisted of chemical, physical, and analytical studies to define an axially-grooved tube geometry that could be successfully fabricated and provide the desired long term (up to seven years) performance is presented. Heat pipe fabrication procedures, measured performance and accelerated life testing of heat pipes S/Ns AL-5 and LT-57 conducted at B and K Engineering are discussed. S/N AL-5 was the first axially-grooved copper/water heat pipe that was fabricated with the new internal coating process for cupric oxide (CuO) and the cleaning and water preparation methods developed by Battelle Columbus Laboratories. Heat pipe S/N LT-57 was fabricated along with sixty other axially-grooved heat pipes allocated for life testing at Teledyne Energy Systems. As of June 25, 1979, heat pipes S/Ns AL-5 and LT-57 have been accelerated life tested for 13,310 and 6,292 respectively, at a nominal operating temperature of 225 0 C without any signs of thermal performance degradation

Safety aspects of targets for ADTT: Activity, volatile products, residual heat release

International Nuclear Information System (INIS)

Gai, E.V.; Ignatyuk, A.V.; Lunev, V.P.; Shubin, Yu.N.

1999-01-01

Safety aspects of heavy metal liquid targets for the accelerator driven systems connected with the activity accumulation and residual energy release due to the irradiation with high energy proton beam are discussed. The results obtained for the lead-bismuth target that are under construction in IPPE now in the frame of ISTC Project No. 559 are briefly presented. The calculations and the analysis of the accumulation of the spallation reaction products, activity and energy release at various moments after the accelerator shutdown are presented. The concentrations of the reaction products, the total and partial activities, the activities of volatile products are determined. The contributions of the short-lived nuclides important for the prediction of the facility behaviour in regimes with the accelerator beam trips. The calculations and analysis of the residual energy release due to different decay type have been performed. The conclusions are as follows. The obtained results showed that long lived radioactivity accumulates mainly due to primary nuclear reactions. Secondary reactions are responsible for the production of small number of long-lived isotopes Bi-207, Po-210 and some others, being generated by radiative capture of low energy neutrons. It is possible to make a conclusion that neutrons in the energy range 20 - 800 MeV and protons with energy above 100 MeV give main contribution to the total activity generation although these parts of spectra inside the target give comparatively small contribution to the total flux. The correct consideration of short-lived nuclides contribution is the main problem in the analysis of the target behaviour in the case of short accelerator shutdowns. They make the determining contribution to the both activity and the heat release at the first moments after the accelerator shutdown, creating the intermediate links and additional channels for the long-lived nuclides accumulation chains. The strong dependence of calculated

Decay heat uncertainty quantification of MYRRHA

Directory of Open Access Journals (Sweden)

Fiorito Luca

2017-01-01

Full Text Available MYRRHA is a lead-bismuth cooled MOX-fueled accelerator driven system (ADS currently in the design phase at SCK·CEN in Belgium. The correct evaluation of the decay heat and of its uncertainty level is very important for the safety demonstration of the reactor. In the first part of this work we assessed the decay heat released by the MYRRHA core using the ALEPH-2 burnup code. The second part of the study focused on the nuclear data uncertainty and covariance propagation to the MYRRHA decay heat. Radioactive decay data, independent fission yield and cross section uncertainties/covariances were propagated using two nuclear data sampling codes, namely NUDUNA and SANDY. According to the results, 238U cross sections and fission yield data are the largest contributors to the MYRRHA decay heat uncertainty. The calculated uncertainty values are deemed acceptable from the safety point of view as they are well within the available regulatory limits.

Comparison of accelerator technologies for use in ADSS

International Nuclear Information System (INIS)

Weng, W.T.; Ludewig, H.; Raparia, D.; Trbojevic, D.; Todosow, M.; McIntyre, P.; Sattarov, A.

2011-01-01

Accelerator Driven Subcritical (ADS) fission is an interesting candidate basis for nuclear waste transmutation and for nuclear power generation. ADS can use either thorium or depleted uranium as fuel, operate below criticality, and consume rather than produce long-lived actinides. A case study with a hypothetical, but realistic nuclear core configuration is used to evaluate the performance requirements of the driver proton accelerator in terms of beam energy, beam current, duty factor, beam distribution delivered to the fission core, reliability, and capital and operating cost. Comparison between a CW IC and that of a SRF proton linac is evaluated. Future accelerator R and D required to improve each candidate accelerator design is discussed. ADS fission has interesting potential for electric power generation and also for destruction of long-lived actinide waste produced by conventional critical reactors. ADS systems offer several interesting advantages in comparison to critical reactors: (1) ADS provides greater flexibility for the composition and placement of fissile, fertile, or fission product waste within the core, and require less enrichment of fissile content; (2) The core can be operated with a reactivity k eff that cannot reach criticality by any failure mode; (3) When the beam is shut off fission ceases in the core; (4) Coupling the fast neutron spectrum of the spallation drive to fast core neutronics offers a basis for more complete burning of long-lived actinides; and (5) ADS designs can provide sufficient thermal mass that meltdown cannot occur from radioactive heat after fission is stopped. In order to drive a ∼GW e fission core a CW proton beam of >700 MeV and ∼15 MW beam power is required. A previous study of the accelerator performance required for ADS systems concluded that present accelerator performance is approaching those requirements, but accelerator system cost and reliability remain particular concerns. The obvious candidates for

Burnout in boiling heat transfer. part I: pool boiling systems

International Nuclear Information System (INIS)

Bergles, A.E.

1977-01-01

Recent experimental and analytical developments in pool-boiling burnout are reviewed, and results are summarized that clarify the dependence of critical heat flux on heater geometry and fluid properties. New analytical interpretations of burnout are discussed, and the effects of surface condition, aging, acceleration, and transient heating (or cooling) are described. The relation of sound to burnout and new techniques for stabilizing electric heaters at burnout are also considered

Cryogenics for high-energy particle accelerators: highlights from the first fifty years

CERN Document Server

AUTHOR|(CDS)2067931

2017-01-01

Applied superconductivity has become a key technology for high-energy particle accelerators, allowing to reach higher beam energy while containing size, capital expenditure and operating costs. Large and powerful cryogenic systems are therefore ancillary to low-temperature superconducting accelerator devices – magnets and high-frequency cavities – distributed over multi-kilometre distances and operating generally close to the normal boiling point of helium, but also above 4.2 K in supercritical and down to below 2 K in superfluid. Additionally, low-temperature operation in accelerators may also be required by considerations of ultra-high vacuum, limited stored energy and beam stability. We discuss the rationale for cryogenics in high-energy particle accelerators, review its development over the past half-century and present its outlook in future large projects, with reference to the main engineering domains of cryostat design and heat loads, cooling schemes, efficient power refrigeration and cryogenic flu...

Body acceleration distribution and O2 uptake in humans during running and jumping

Science.gov (United States)

Bhattacharya, A.; Mccutcheon, E. P.; Shvartz, E.; Greenleaf, J. E.

1980-01-01

The distribution of body acceleration and associated oxygen uptake and heart rate responses are investigated in treadmill running and trampoline jumping. Accelerations in the +Gz direction were measured at the lateral ankle, lumbosacral region and forehead of eight young men during level treadmill walking and running at four speeds and trampoline jumping at four heights, together with corresponding oxygen uptake and heart rate. With increasing treadmill speed, peak acceleration at the ankle is found always to exceed that at the back and forehead, and acceleration profiles with higher frequency components than those observed during jumping are observed. Acceleration levels are found to be more uniformly distributed with increasing height in jumping, although comparable oxygen uptake and heat rates are obtained. Results indicate that the magnitude of the biomechanical stimuli is greater in trampoline jumping than in running, which finding could be of use in the design of procedures to avert deconditioning in persons exposed to weightlessness.

The roles of turbulence on plasma heating

International Nuclear Information System (INIS)

Kawamura, Takaichi; Kawabe, Takaya.

1976-06-01

In this paper, the characteristic features of the turbulent heating are reviewed, which is considered to be one of the strong candidates of the further heating method in fusion reactor systems, referring to the works in the Institute of Plasma Physics, Nagoya University. The roles of turbulence in plasma heating including toroidal plasma heating are discussed from several points of view. The relation between the heating rate of plasma particles and the thermalization (randomization) frequency is theoretically investigated and the role of plasma turbulence in the fast thermalization is shown. The experimental results on fluctuation and heating of electrons and ions in turbulently heated plasmas are presented. The influence of turbulence, which is responsible for the particle heating, on the diffusion across the confinement magnetic field is considered for the application in the toroidal plasmas. It is pointed out that the turbulent fields in the fast turbulent heating give only a minor effect to the loss of particles across the magnetic field. It can be said that the enhanced fluctuation in turbulent plasma gives its field energy to the plasma particles while it can play the role of the fast thermalization of the ordered motion of particles that is produced in the plasma by some acceleration process. (Kato, T.)

Accelerated life assessment of coating on the radar structure components in coastal environment.

Science.gov (United States)

Liu, Zhe; Ming, ZhiMao

2016-07-04

This paper aimed to build an accelerated life test scheme and carry out quantitative analysis between accelerated life test in the laboratory and actual service for the coating composed of epoxy primer and polyurethane paint on structure components of some kind of radar served in the coastal environment of South China Sea. The accelerated life test scheme was built based on the service environment and failure analysis of the coating. The quantitative analysis between accelerated life test and actual service was conducted by comparing the gloss loss, discoloration, chalking, blistering, cracking and electrochemical impedance spectroscopy of the coating. The main factors leading to the coating failure were ultraviolet radiation, temperature, moisture, salt fog and loads, the accelerated life test included ultraviolet radiation, damp heat, thermal shock, fatigue and salt spray. The quantitative relationship was that one cycle of the accelerated life test was equal to actual service for one year. It was established that one cycle of the accelerated life test was equal to actual service for one year. It provided a precise way to predict actual service life of newly developed coatings for the manufacturer.

Monte-Carlo Simulation of the Features of Bi-Reactior Accelerator Driven Systems

CERN Document Server

Bznuni, S A; Khudaverdian, A G; Barashenkov, V S; Sosnin, A N; Polyanskii, A A

2002-01-01

Parameters of accelerator-driven systems containing two "cascade" subcritical assemblies (liquid metal fast reactor, used as a neutron booster, and a thermal reactor, where main heat production is taking place) are investigated. Three main reactor cores analogous to VVER-1000, MSBR-1000 and CANDU-6 reactors are considered. Functioning in a safe mode (k_{eff}=0.94-0.98) these systems under consideration demonstrate much larger capacity in the wide range of k_{eff} in comparison with analogous systems without intermediate fast booster reactor and simultaneously having the density of thermal neutron flux equal to Phi^{max}=10^{14} cm^{-2}c^{-1} and operating with the fast and thermal zones they are capable to transmute the whole scope of nuclear waste reducing the requirements on the beam current of the accelerator by one order of magnitude. It seems to be the most important in case when molten salt thermal breeder reactor cores are considered as a main heat generating zone.

HEATING-7, Multidimensional Finite-Difference Heat Conduction Analysis

International Nuclear Information System (INIS)

2000-01-01

problems, surface fluxes may be plotted with H7TECPLOT which requires the proprietary software TECPLOT. HEATING 7.3 runs under Windows95 and WindowsNT on PC's. No future modifications are planned for HEATING7. See README.1ST for more information. 2 - Method of solution: Three steady-state solution techniques are available: point-successive over-relaxation iterative method with extrapolation, direct-solution (for one-dimensional or two-dimensional problems), and conjugate gradient. Transient problems may be solved using any one of several finite-difference schemes: Crank-Nicolson implicit, Classical Implicit Procedure (CIP), Classical Explicit Procedure (CEP), or Levy explicit method (which for some circumstances allows a time step greater than the CEP stability criterion.) The solution of the system of equations arising from the implicit techniques is accomplished by point-successive over-relaxation iteration and includes procedures to estimate the optimum acceleration parameter. 3 - Restrictions on the complexity of the problem: All surfaces in a model must be parallel to one of the coordinate axes which makes modeling complex geometries difficult. Transient change of phase problems can only be solved with one of the explicit techniques - an implicit change-of-phase capability has not been implemented

Development of compact low energy election beam accelerator

International Nuclear Information System (INIS)

Katsura, Ichiro

1996-01-01

Sumitomo Heavy Industries has developed new compact accelerator jointly with its affiliated company RPC industries and some of which have already been in use in industries. Named WIPL, or WIP, which stands for Wire Ion Plasma, this accelerator is almost half the size of existing accelerators yet with performance as high as well enough to cope with industrial requirements. Background of our determination to develop such accelerator was that there prevails fairly good numbers of small laboratory units but only small numbers of production machines are in use. The main reason which brought such environment was that those production units were husky and costly. To overcome such problem and to turn situation in favor we launched the development programme and eventually succeeded to complete WIPL. Unique feature of WIPL was materialized by adopting special method of generating electrons. Unlike existing accelerators which use heated filaments WIPL utilizes the system using electron emission by bombardment of cathode plate by helium ions as electron source. Electrons are to be generated in following manner. 1) Thin helium gas is introduced in plasma chamber in which wire(s) for applying electric power. When power is supplied helium gas is turned into helium plasma by electric field. 2) Being energized by separate high voltage power source cathode plate is charged minus simultaneously. 3) Plus charged helium ions in plasma are then accelerated toward cathode plate and hit the surface. 4) Cathode plate emits electrons by bombardment and emitted electrons are compelled by the field and accelerated to the direction which helium ion came. Since such system no longer requires insulated transformers and control system for controlling electron beam current used in filament type machines equipment becomes remarkably small and economical. We really hope that this machine is accepted widely and contributes for exploiting the new horizon of electron beam market. (author)

Prompt acceleration of ions by oblique turbulent shocks in solar flares

Science.gov (United States)

Decker, R. B.; Vlahos, L.

1985-01-01

Solar flares often accelerate ions and electrons to relativistic energies. The details of the acceleration process are not well understood, but until recently the main trend was to divide the acceleration process into two phases. During the first phase elctrons and ions are heated and accelerated up to several hundreds of keV simultaneously with the energy release. These mildly relativistic electrons interact with the ambient plasma and magnetic fields and generate hard X-ray and radio radiation. The second phase, usually delayed from the first by several minutes, is responsible for accelerating ions and electrons to relativistic energies. Relativistic electrons and ions interact with the solar atmosphere or escape from the Sun and generate gamma ray continuum, gamma ray line emission, neutron emission or are detected in space by spacecraft. In several flares the second phase is coincident with the start of a type 2 radio burst that is believed to be the signature of a shock wave. Observations from the Solar Maximum Mission spacecraft have shown, for the first time, that several flares accelerate particles to all energies nearly simultaneously. These results posed a new theoretical problem: How fast are shocks and magnetohydrodynamic turbulence formed and how quickly can they accelerate ions to 50 MeV in the lower corona? This problem is discussed.

Prompt acceleration of ions by oblique turbulent shocks in solar flares

International Nuclear Information System (INIS)

Decker, R.B.; Vlahos, L.

1985-01-01

Solar flares often accelerate ions and electrons to relativistic energies. The details of the acceleration process are not well understood, but until recently the main trend was to divide the acceleration process into two phases. During the first phase elctrons and ions are heated and accelerated up to several hundreds of keV simultaneously with the energy release. These mildly relativistic electrons interact with the ambient plasma and magnetic fields and generate hard x-ray and radio radiation. The second phase, usually delayed from the first by several minutes, is responsible for accelerating ions and electrons to relativistic energies. Relativistic electrons and ions interact with the solar atmosphere or escape from the Sun and generate gamma ray continuum, gamma ray line emission, neutron emission or are detected in space by spacecraft. In several flares the second phase is coincident with the start of a type 2 radio burst that is believed to be the signature of a shock wave. Observations from the Solar Maximum Mission spacecraft have shown, for the first time, that several flares accelerate particles to all energies nearly simultaneously. These results posed a new theoretical problem: How fast are shocks and magnetohydrodynamic turbulence formed and how quickly can they accelerate ions to 50 MeV in the lower corona. This problem is discussed

Auroral particle acceleration by Alfvén waves and ionospheric feedback

Science.gov (United States)

Lysak, R. L.; Song, Y.

2003-12-01

Recent observations, particularly by Polar and FAST, have indicated that Alfvén waves can directly accelerate auroral electrons. A model for this interaction has been developed that can describe the linear modification of the Alfvén wave profile by the kinetic effects of electrons, including acceleration and heating of the electron population. While many of the heated electrons are accelerated upward into the magnetosphere by the mirror force, a significant fraction of the input Poynting flux due to Alfvén waves can be converted into precipitating electron energy flux. An important aspect of this particle precipitation is that the hot electrons do not arrive at the ionosphere in phase with the field-aligned current, which at ionospheric altitudes is largely carried by cold electrons. This phase shift has direct implications for models of ionospheric feedback that usually assume that the precipitating flux is in phase with the field-aligned current. The effects of quasi-static electric fields can be included in the model, which will introduce new particle populations such as the effects of secondary electrons of ionospheric origin that are reflected by the parallel potential drop. The possible role of Alfvén waves trapped in the ionospheric resonator in creating small-scale auroral structures through feedback and nonlinear interactions will be discussed.

Use of zooming and pulseshaping for acceleration to high velocities and fusion neutron production on the Nike laser

Science.gov (United States)

Karasik, Max; Weaver, J. L.; Aglitskiy, Y.; Kehne, D. M.; Zalesak, S. T.; Velikovich, A. L.; Oh, J.; Obenschain, S. P.; Arikawa, Y.

2011-10-01

We will present results from follow-on experiments to the record-high velocities of 1000 km/s achieved on Nike [Karasik et al, Phys. Plasmas 17, 056317(2010)], in which highly accelerated planar foils of deuterated polystyrene were made to collide with a witness foil to produce ~ 1 Gbar shock pressures and result in heating of matter to thermonuclear temperatures. Still higher velocities and higher target densities are required for impact fast ignition. The aim of these experiments is using the focal zoom capability of Nike and shaping the driving pulse to minimize shock heating of the accelerated target to achieve higher densities and velocities. In-flight target density is inferred from target heating upon collision via DD neutron time-of-flight ion temperature measurement. Work is supported by US DOE (NNSA) and Office of Naval Research. SAIC

Resonant heating of a cluster plasma by intense laser light

International Nuclear Information System (INIS)

Antonsen, Thomas M. Jr.; Taguchi, Toshihiro; Gupta, Ayush; Palastro, John; Milchberg, Howard M.

2005-01-01

Gases of atomic clusters are interaction media for laser pulse propagation with properties useful for applications such as extreme ultraviolet (EUV) and x-ray microscopy, harmonic generation, EUV lithography, and laser plasma acceleration. To understand cluster heating and expansion, a series of two- and three-dimensional electrostatic particle in cell simulations of the explosion of argon clusters of diameter in the range 20 nm-53 nm have been preformed. The studies show that heating is dominated by a nonlinear, resonant absorption process that gives rise to a size-dependent intensity threshold for strong absorption and that controls the dielectric properties of the cluster. Electrons are first accelerated out from the cluster and then driven back into it by the combined effects of the laser field and the electrostatic field produced by the laser-driven charge separation. Above the intensity threshold for strong heating there is a dramatic increase in the production of energetic particles and harmonic radiation. The dielectric properties of a gas of clusters are determined by the ensemble average cluster polarizability. Individual electrons contribute to the polarizability differently depending on whether they are in the core of the cluster or in the outer edge. Consequently, there can be large fluctuations in polarizability during the heating of a cluster

Design change of tower cooling water system for proton accelerator research center

International Nuclear Information System (INIS)

Jeon, G. P.; Kim, J. Y.; Song, I. T.; Min, Y. S.; Mun, K. J.; Cho, J. S.; Nam, J. M.; Park, S. S.; Han, Y. G.

2012-01-01

The Tower Cooling Water System (TC) is designed to reject the heat load generated by operating the accelerators and the utility facilities through the component cooling water (CCW) heat exchangers. The circulating water discharged from the circulating water pumps passes through the CCW heat exchangers, the Chiller condenser and the air compressor, and the heated circulating water is return to the cooling tower for the heat removal. In this study, The design of Tower Cooling Water System is changed as follows : At First, The quantity of cells is changed into six in order to operate the cooling tower accurately correspond with condition of each equipment of head loads. The fans of cooling tower are controlled by the signal of TEW installed in the latter parts of it. The type of circulation water pump is modified to centrifugal pump and debris filter system is deleted

Design change of tower cooling water system for proton accelerator research center

Energy Technology Data Exchange (ETDEWEB)

Jeon, G. P.; Kim, J. Y.; Song, I. T.; Min, Y. S.; Mun, K. J.; Cho, J. S.; Nam, J. M.; Park, S. S.; Han, Y. G. [KAERI, Daejeon (Korea, Republic of)

2012-10-15

The Tower Cooling Water System (TC) is designed to reject the heat load generated by operating the accelerators and the utility facilities through the component cooling water (CCW) heat exchangers. The circulating water discharged from the circulating water pumps passes through the CCW heat exchangers, the Chiller condenser and the air compressor, and the heated circulating water is return to the cooling tower for the heat removal. In this study, The design of Tower Cooling Water System is changed as follows : At First, The quantity of cells is changed into six in order to operate the cooling tower accurately correspond with condition of each equipment of head loads. The fans of cooling tower are controlled by the signal of TEW installed in the latter parts of it. The type of circulation water pump is modified to centrifugal pump and debris filter system is deleted.

Qualification of stainless steel for OTEC heat exchanger tubes

Energy Technology Data Exchange (ETDEWEB)

LaQue, F.L.

1979-01-01

The history of the AL-6X alloy is reviewed and its credentials as a candidate for use as tubing in Ocean Thermal Energy Conversion Heat Exchangers are examined. Qualification is based on results of accelerated tests using ferric chloride for resistance to crevice corrosion and pitting, long-time crevice corrosion and pitting tests in natural sea water and anticipated resistance to attack by ammonia and mixtures of ammonia and sea water. Since the alloy has no natural resistance to fouling by marine organisms, it must be able to accomodate action to prevent fouling by chlorination or to remove it by mechanical cleaning techniques or appropriate chemical cleaning methods. The satisfactory behavior indicated by the various accelerated and long-time corrosion tests has been confirmed by excellent performance of several million feet of tubing in condensers in coastal power plants. Early evaluation tests demonstrated the need for proper heat treatment to avoid the presence of a sigma phase, which promoted severe pitting of some, but not all, specimens in tests in natural sea water. The available data qualify the AL-6X alloy as being a satisfactory alternate to titanium for tubes in OTEC heat exchangers.

Heat transfer augmentation for high heat flux removal in rib-roughened narrow channels

International Nuclear Information System (INIS)

Islam, M.S.; Hino, Ryutaro; Haga, Katsuhiro; Sudo, Yukio; Monde, Masanori.

1997-03-01

Heat transfer augmentation in narrow rectangular channels in a target system is a very important method to remove high heat flux up to 12 MW/m 2 generated at target plates of a high-intensity proton accelerator of 1.5 GeV and 1 mA with a proton beam power of 1.5 MW. In this report, heat transfer coefficients and friction factors in narrow rectangular channels with one-sided rib-roughened surface were evaluated for fully developed flows in the range of the Reynolds number from 6,000 to 1,00,000; the rib pitch-to-height ratios (p/k) were 10,20 and 30; the rib height-to-equivalent diameter ratios (k/De) were 0.025, 0.03 and 0.1 by means of previous existing experimental correlations. The rib-roughened surface augmented heat transfer coefficients approximately 4 times higher than the smooth surface at Re=10,000, p/k=10 and k/De=0.1; friction factors increase around 22 times higher. In this case, higher heat flux up to 12 MW/m 2 could be removed from the rib-roughened surface without flow boiling which induces flow instability; but pressure drop reaches about 1.8 MPa. Correlations obtained by air-flow experiments have showed lower heat transfer performance with the water-flow conditions. The experimental apparatus was proposed for further investigation on heat transfer augmentation in very narrow channels under water-flow conditions. This report presents the evaluation results and an outline of the test apparatus. (author)

Effect of re-heating on the hot electron temperature

International Nuclear Information System (INIS)

Estabrook, K.; Rosen, M.

1980-01-01

Resonant absorption is the direct conversion of the transverse laser light to longitudinal electron plasma waves (epw) at the critical density [10 21 (1.06 μm/lambda 0 ) 2 cm -3 ]. The oscillating longitudinal electric field of the epw heats the electrons by accelerating them down the density gradient to a temperature of approximately 21T/sub e/ 0 25 ([I(W/cm 2 )/10 16 ](lambda 0 /1.06 μm) 2 ) 0 4 . This section extends the previous work by studying the effects of magnetic fields and collisions (albedo) which return the heated electrons for further heating. A magnetic field increases their temperature and collisions do not

Pulsed radiofrequency microwave fields around a quadrupole particle accelerator: measurement and safety evaluation

International Nuclear Information System (INIS)

Sachdev, R.N.; Swarup, G.; Rajan, K.K.; Joseph, L.

1996-01-01

Pulsed radiofrequency microwave radiation (RFMR) fields occur during the use of high power microwaves in plasma heating in fusion research, plasma and solid state diagnostics, particle accelerators and colliders, pump sources in lasers, material processing as well as in high power radars. This paper describes the experimental work done at Trombay for measurement of pulsed RFMR fields in the working area of a radiofrequency quadrupole (RFQ) accelerator with the use of a meter calibrated in continuous field and interprets the observed fields in the light of existing protection criteria for pulsed RFMR fields. (author)

Fluid Mechanics and Heat Transfer in Transitional Boundary Layers

Science.gov (United States)

Wang, Ting

2007-01-01

Experiments have been performed to investigate the effects of elevated free-stream turbulence and streamwise acceleration on flow and thermal structures in transitional boundary layers. The free-stream turbulence ranges from 0.5 to 6.4% and the streamwise acceleration ranges from K = 0 to 0.8 x 10(exp -6). The onset of transition, transition length and the turbulent spot formation rate are determined. The statistical results and conditionally sampled results of th streamwise and cross-stream velocity fluctuations, temperature fluctuations, Reynolds stress and Reynolds heat fluxes are presented.

About calculation results of heat transfer in the fuel assembly clusters cooled by water with supercritical parameters

International Nuclear Information System (INIS)

Grabezhnaya, V.A.

2008-01-01

Paper reviews the numerical investigation into the heat transfer in the supercritical water cooled fuel assemblies on the basis of the various commercial codes. The turbulence available models specified in the codes describe adequately the experimental data in tubes within the range of flow temperatures away from the pseudocritical point, as well as under high mass velocities. There are k-ε type turbulence models that show qualitatively the local acceleration (slowdown) of the heat transfer in tubes, but they fail to describe the mentioned phenomena quantitatively. To determine the effect of grid spacers on the suppression of the heat transfer local slowdown and on the heat transfer acceleration in fuel assemblies and to ensure more accurate calculation of the fuel element cladding maximum temperature one should perform a number of the experiments making use of the fuel assembly models [ru

Applications of electron accelerator in Malaysia

Energy Technology Data Exchange (ETDEWEB)

Khairul Zaman Hj. Mohd Dahlan [Malaysian Institute for Nuclear Technology Research (MINT), Bangi, Selangor Darul Ehsan (Malaysia)

2003-02-01

Current status of radiation processing, as one of the core research programs of the Malaysian Institute for Nuclear Technology Research (MINT), is presented. Industrial applications of six electron accelerators from 150 kV up to 3 MV in Malaysia now in operation are mainly for curing of surface coatings, crosslinking of tubes, heat shrinkable tubes and packaging films, crosslinking of wire insulation. Their performances are listed. New technology now in R and D stage includes natural rubber, sago starch and chitosan for biomedical applications, and radiation curable materials from oil palm for pressure sensitive adhesive and printing ink. (S. Ohno)

Applications of electron accelerator in Malaysia

International Nuclear Information System (INIS)

Khairul Zaman Hj. Mohd Dahlan

2003-01-01

Current status of radiation processing, as one of the core research programs of the Malaysian Institute for Nuclear Technology Research (MINT), is presented. Industrial applications of six electron accelerators from 150 kV up to 3 MV in Malaysia now in operation are mainly for curing of surface coatings, crosslinking of tubes, heat shrinkable tubes and packaging films, crosslinking of wire insulation. Their performances are listed. New technology now in R and D stage includes natural rubber, sago starch and chitosan for biomedical applications, and radiation curable materials from oil palm for pressure sensitive adhesive and printing ink. (S. Ohno)

The use and potential application of electron accelerator in Indonesia

International Nuclear Information System (INIS)

Danu, Sugiarto

2003-01-01

The use of electron accelerator in Indonesia for research and development, radiation services, commercial purposes and potential application in the future is described. A pilot plant for radiation curing technology particularly for wood surface coating using low energy electron accelerator (300 keV, 50 mA; installed in 1984) and a EBM GJ 2 (2 MeV, 10 mA, installed in 1994) for R and D of crosslinking process such as wire and cable and heat shrinkable tube and sheets in Center for Research and Development of Isotopes and Radiation Technology, Jakarta, and also a low energy electron accelerator (installed in 1998) in a private company, PT Gajah Tunggai, are being mainly used. Their performances are presented with activities achieved in the fields of wood surface coating, vulcanization of natural rubber latex, grafting of polyethylene terephthalate (PET), radiation sterilization, degradation of cellulose and, as promising applications, radiation curing for composite production and uses for environmental preservation are introduced. (S. Ohno)

The use and potential application of electron accelerator in Indonesia

Energy Technology Data Exchange (ETDEWEB)

Danu, Sugiarto [National Nuclear Energy Agency, Center for Research and Development of Isotopes and Radiation Technology, Jakarta (Indonesia)

2003-02-01

The use of electron accelerator in Indonesia for research and development, radiation services, commercial purposes and potential application in the future is described. A pilot plant for radiation curing technology particularly for wood surface coating using low energy electron accelerator (300 keV, 50 mA; installed in 1984) and a EBM GJ 2 (2 MeV, 10 mA, installed in 1994) for R and D of crosslinking process such as wire and cable and heat shrinkable tube and sheets in Center for Research and Development of Isotopes and Radiation Technology, Jakarta, and also a low energy electron accelerator (installed in 1998) in a private company, PT Gajah Tunggai, are being mainly used. Their performances are presented with activities achieved in the fields of wood surface coating, vulcanization of natural rubber latex, grafting of polyethylene terephthalate (PET), radiation sterilization, degradation of cellulose and, as promising applications, radiation curing for composite production and uses for environmental preservation are introduced. (S. Ohno)

Reducing field emission in the superconducting rf cavities for the next generation of particle accelerators

International Nuclear Information System (INIS)

Shu, Q.S.; Hartung, W.; Leibovich, A.; Kirchgessner, J.; Moffat, D.; Padamsee, H.; Rubin, D.; Sears, J.

1991-01-01

This paper reports on field emission, which is an obstacle to reaching the higher fields called for in future applications of superconducting radio frequency cavities to particle accelerators. The authors used heat treatment up to 1500 degrees C in an ultra-high vacuum furnace, along with processing of cavities and temperature mapping, to suppress field emission and analyze emitter properties. In 27 tests of 1-cell 1500 MHz fired accelerating cavities, on the average the accelerating field E acc increased to 24 MV/m (H pk = 1250 Oe) from 13 MV/m with chemical treatment alone; the highest E acc reached was 30.5 MV/m

Sequential accelerated tests: Improving the correlation of accelerated tests to module performance in the field

Science.gov (United States)

Felder, Thomas; Gambogi, William; Stika, Katherine; Yu, Bao-Ling; Bradley, Alex; Hu, Hongjie; Garreau-Iles, Lucie; Trout, T. John

2016-09-01

DuPont has been working steadily to develop accelerated backsheet tests that correlate with solar panels observations in the field. This report updates efforts in sequential testing. Single exposure tests are more commonly used and can be completed more quickly, and certain tests provide helpful predictions of certain backsheet failure modes. DuPont recommendations for single exposure tests are based on 25-year exposure levels for UV and humidity/temperature, and form a good basis for sequential test development. We recommend a sequential exposure of damp heat followed by UV then repetitions of thermal cycling and UVA. This sequence preserves 25-year exposure levels for humidity/temperature and UV, and correlates well with a large body of field observations. Measurements can be taken at intervals in the test, although the full test runs 10 months. A second, shorter sequential test based on damp heat and thermal cycling tests mechanical durability and correlates with loss of mechanical properties seen in the field. Ongoing work is directed toward shorter sequential tests that preserve good correlation to field data.

Plasma jet acceleration of dust particles to hypervelocities

International Nuclear Information System (INIS)

Ticos, C. M.; Wang, Zhehui; Wurden, G. A.; Kline, J. L.; Montgomery, D. S.

2008-01-01

A convenient method to accelerate simultaneously hundreds of micron-size dust particles to a few km/s over a distance of about 1 m is based on plasma drag. Plasma jets which can deliver sufficient momentum to the dust particles need to have speeds of at least several tens of km/s, densities of the order of 10 22 m -3 or higher, and low temperature ∼1 eV, in order to prevent dust destruction. An experimental demonstration of dust particles acceleration to hypervelocities by plasma produced in a coaxial gun is presented here. The plasma flow speed is deduced from photodiode signals while the plasma density is measured by streaked spectroscopy. As a result of the interaction with the plasma jet, the dust grains are also heated to high temperatures and emit visible light. A hypervelocity dust shower is imaged in situ with a high speed video camera at some distance from the coaxial gun, where light emission from the plasma flow is less intense. The bright traces of the flying microparticles are used to infer their speed and acceleration by employing the time-of-flight technique. A simple model for plasma drag which accounts for ion collection on the grain surface gives predictions for dust accelerations which are in good agreement with the experimental observations.

Plasma accelerators

International Nuclear Information System (INIS)

Bingham, R.; Angelis, U. de; Johnston, T.W.

1991-01-01

Recently attention has focused on charged particle acceleration in a plasma by a fast, large amplitude, longitudinal electron plasma wave. The plasma beat wave and plasma wakefield accelerators are two efficient ways of producing ultra-high accelerating gradients. Starting with the plasma beat wave accelerator (PBWA) and laser wakefield accelerator (LWFA) schemes and the plasma wakefield accelerator (PWFA) steady progress has been made in theory, simulations and experiments. Computations are presented for the study of LWFA. (author)

Upright heat exchanger

International Nuclear Information System (INIS)

Martoch, J.; Kugler, V.; Krizek, V.; Strmiska, F.

1988-01-01

The claimed heat exchanger is characteristic by the condensate level being maintained directly in the exchanger while preserving the so-called ''dry'' tube plate. This makes it unnecessary to build another pressure vessel into the circuit. The design of the heat exchanger allows access to both tube plates, which facilitates any repair. Another advantage is the possibility of accelerating the indication of leakage from the space of the second operating medium which is given by opening the drainage pipes of the lower bundle into the collar space and from there through to the indication pipe. The exchanger is especially suitable for deployment in the circuits of nuclear power plants where the second operating medium will be hot water of considerably lower purity than is that of the condensate. A rapid display of leakage can prevent any long-term penetration of this water into the condensate, which would result in worsening water quality in the entire secondary circuit of the nuclear power plant. (J.B.). 1 fig

The effect of bubble acceleration on the liquid film thickness in micro tubes

Energy Technology Data Exchange (ETDEWEB)

Han, Youngbae, E-mail: bhan@feslab.t.u-tokyo.ac.j [Department of Mechanical Engineering, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8656 (Japan); Shikazono, Naoki, E-mail: shika@feslab.t.u-tokyo.ac.j [Department of Mechanical Engineering, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8656 (Japan)

2010-08-15

Liquid film thickness is an important parameter for predicting boiling heat transfer in micro tubes. In the previous study (), liquid film thickness under the steady condition was investigated and an empirical correlation for the initial liquid film thickness based on capillary number, Reynolds number and Weber number was proposed. However, under flow boiling conditions, bubble velocity is not constant but accelerated due to evaporation. It is necessary to consider this bubble acceleration effect on the liquid film thickness, since it affects viscous, surface tension and inertia forces in the momentum equation. In addition, viscous boundary layer develops, and it may also affect the liquid film thickness. In the present study, the effect of bubble acceleration is investigated. Laser focus displacement meter is used to measure the liquid film thickness. Ethanol, water and FC-40 are used as working fluids. Circular tubes with three different inner diameters, D = 0.5, 0.7 and 1.0 mm, are used. The increase of liquid film thickness with capillary number is restricted by the bubble acceleration. Finally, an empirical correlation is proposed for the liquid film thickness of accelerated flows in terms of capillary number and Bond number based on the bubble acceleration.

The effect of bubble acceleration on the liquid film thickness in micro tubes

International Nuclear Information System (INIS)

Han, Youngbae; Shikazono, Naoki

2010-01-01

Liquid film thickness is an important parameter for predicting boiling heat transfer in micro tubes. In the previous study (), liquid film thickness under the steady condition was investigated and an empirical correlation for the initial liquid film thickness based on capillary number, Reynolds number and Weber number was proposed. However, under flow boiling conditions, bubble velocity is not constant but accelerated due to evaporation. It is necessary to consider this bubble acceleration effect on the liquid film thickness, since it affects viscous, surface tension and inertia forces in the momentum equation. In addition, viscous boundary layer develops, and it may also affect the liquid film thickness. In the present study, the effect of bubble acceleration is investigated. Laser focus displacement meter is used to measure the liquid film thickness. Ethanol, water and FC-40 are used as working fluids. Circular tubes with three different inner diameters, D = 0.5, 0.7 and 1.0 mm, are used. The increase of liquid film thickness with capillary number is restricted by the bubble acceleration. Finally, an empirical correlation is proposed for the liquid film thickness of accelerated flows in terms of capillary number and Bond number based on the bubble acceleration.

Van-de-Graaf accelerator operation with laser source of highly-charged heavy ions

International Nuclear Information System (INIS)

Barabash, L.S.; Golubev, A.A.; Koshkarev, S.G.; Krechet, K.I.; Sharkov, B.Y.; Shumshurov, A.V.

1988-01-01

Multicharged ions (Z = +1 divided-by +10) of practically any elements of the periodical table have been generated by the laser source based on a simple in operation and fabrication laser. One of the features of the laser source is that the energy needed for plasma heating is transported to the target from a great distance. In this case the target can be placed under high voltage or in a magnetic field. These advantages of the laser source are particularly important for its application in the Van-de-Graaf accelerator, where absence of resonance units allows to accelerate ions with any charge-to-mass ratio. The goal of this paper consists in designing a laser source of highly- charged heavy ions in the Van-de-Graaf accelerator and in measuring charge spectra of the accelerated ion beam. The peculiarities of this accelerator are taken into account in the discussion of the source scheme. Such peculiarities include potential up to 5 MV on the high-voltage conductor, where the ion source is placed, and high up to 15 atm gas environment pressure

Plasma acceleration using. mu. -gradient(B) force

Energy Technology Data Exchange (ETDEWEB)

Nihei, H; Inoue, N; Ohara, Y; Nishino, O [Tokyo Univ. (Japan). Faculty of Engineering

1973-12-01

Several types of high flux beam sources have been developed for the purpose of heating and fuel feeding of the fusion reactor plasma. In our laboratory a duoPIGatron ion source and a ..mu..gradient B plasma accelerator are constructed. The former is used for the production of the beam with the energy of higher than several keV, and the latter is for the lower energy beam. The present paper describes the results of experiments on the ..mu..gradient B plasma accelerator. The absolute intensity of the beam is obtained by calorimetric measurement. The beam intensity increases as the microwave input power increases. Distribution of beam energy is measured with a multigrid electrostatic analyzer. The average energy of ions is about 60 eV and the total current is 0.5 A. In addition to the fusion reactor application, such a type of low energy and high intensity beam source is applicable to the investigation of atomic processes and the space craft propulsion.

Second Sound for Heat Source Localization

CERN Document Server

Vennekate, Hannes; Uhrmacher, Michael; Quadt, Arnulf; Grosse-Knetter, Joern

2011-01-01

Defects on the surface of superconducting cavities can limit their accelerating gradient by localized heating. This results in a phase transition to the normal conduction state | a quench. A new application, involving Oscillating Superleak Transducers (OST) to locate such quench inducing heat spots on the surface of the cavities, has been developed by D. Hartill et al. at Cornell University in 2008. The OSTs enable the detection of heat transfer via second sound in super uid helium. This thesis presents new results on the analysis of their signal. Its behavior has been studied for dierent circumstances at setups at the University of Gottingen and at CERN. New approaches for an automated signal processing have been developed. Furthermore, a rst test setup for a single-cell Superconducting Proton Linac (SPL) cavity has been prepared. Recommendations of a better signal retrieving for its operation are presented.

Space qualification of high capacity grooved heat pipes

Energy Technology Data Exchange (ETDEWEB)

Dubois, M; Mullender, B; Druart, J [SABCA, Societe Anomyme Belgel de Construction Aeronautique (Belgium); Supper, W; Beddows, A [ESTEC-The (Netherlands)

1997-12-31

Based on the thermal requirements of the future telecommunication satellites, the development of a High Capacity Grooved Heat Pipe (HPG), was contracted by ESA to SABCA leading to an aluminium extruded heat pipe (outer diameter of 25 mm) based on a multi re-entrant grooves design. After an intensive acceptance test campaign whose results showed a good confidence in the design and the fulfillment of the required specifications of heat transport and on tilt capability (experimental maximum heat transport capability of 1500 Watt metres for a vapour temperature of 20 deg C), similar heat pipes have been developed with various outer diameters (11 mm, 15 mm and 20 mm) and with various shapes (circular outer shapes, integrated saddles). Several of these heat pipes were tested during two parabolic flight campaigns, by varying the heat loads during the micro-gravity periods. This HGP heat pipe family is now being submitted to a space qualification program according to ESA standards (ESA PSS-49), both in straight and bent configuration. Within this qualification, the heat pipes are submitted to an extended test campaign including environmental (random/sinus vibration, constant acceleration) and thermal tests (thermal performance, thermal cycle, thermal soak, ageing). (authors) 9 refs.

Space qualification of high capacity grooved heat pipes

Energy Technology Data Exchange (ETDEWEB)

Dubois, M.; Mullender, B.; Druart, J. [SABCA, Societe Anomyme Belgel de Construction Aeronautique (Belgium); Supper, W.; Beddows, A. [ESTEC-The (Netherlands)

1996-12-31

Based on the thermal requirements of the future telecommunication satellites, the development of a High Capacity Grooved Heat Pipe (HPG), was contracted by ESA to SABCA leading to an aluminium extruded heat pipe (outer diameter of 25 mm) based on a multi re-entrant grooves design. After an intensive acceptance test campaign whose results showed a good confidence in the design and the fulfillment of the required specifications of heat transport and on tilt capability (experimental maximum heat transport capability of 1500 Watt metres for a vapour temperature of 20 deg C), similar heat pipes have been developed with various outer diameters (11 mm, 15 mm and 20 mm) and with various shapes (circular outer shapes, integrated saddles). Several of these heat pipes were tested during two parabolic flight campaigns, by varying the heat loads during the micro-gravity periods. This HGP heat pipe family is now being submitted to a space qualification program according to ESA standards (ESA PSS-49), both in straight and bent configuration. Within this qualification, the heat pipes are submitted to an extended test campaign including environmental (random/sinus vibration, constant acceleration) and thermal tests (thermal performance, thermal cycle, thermal soak, ageing). (authors) 9 refs.

Electron beam accelerator facilities at IPEN-CNEN/SP

Energy Technology Data Exchange (ETDEWEB)

Somessari, Samir L.; Silveira, Carlos G. da; Paes, Helio; Somessari, Elizabeth S.R. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], E-mail: somessar@ipen.br

2007-07-01

Electron beam processing is a manufacturing technique, which applies a focused beam of high-energy electrons produced by an electron accelerator to promote chemical changes within a product. At IPEN-CNEN/SP there are two electron beam accelerators Type Dynamitron{sup R} (manufactured by RDI- Radiation Dynamics Inc.) Job 188 and Job 307 models. The technical specifications for the Job 188 energy 1.5 MeV, beam current 25 mA, scan 1.20 m, beam power 37.5 kW and for the Job 307 energy 1.5 MeV, beam current 65 mA, Scan 1.20 m, beam power 97.5 kW. Some applications of the electron beam accelerator for radiation processing are wire and cable insulation crosslinking, rubber vulcanization, sterilization and disinfection of medical products, food preservation, heat shrinkable products, polymer degradation, aseptic packaging, semiconductors and pollution control. For irradiating these materials at IPEN-CNEN/SP, there are some equipment such as, underbeam capstan with speed control from 10 to 700 m/min; a track; a system to roll up and unroll wires and electric cables, polyethylene blankets and other systems to improve the quality of the products. (author)

Acceleration of two-phase flow by boiling, 1

International Nuclear Information System (INIS)

Hara, Toshitsugu; Uchida, Motokazu; Mitani, Akio; Mori, Yasuo; Hijikata, Kunio.

1975-01-01

This paper reports on the experimental results concerning the acceleration mechanism of the liquid used for liquid metal magnetohydrodynamic power generation. The experiment simulated two-component flow by injecting low boiling point liquid (R113) which is not soluble in main high temperature flow (hot water). From the boiling of this two component flow, the relations among the acceleration performance of the liquid, the number and frequency of bubbles generated from liquid drops, and the growth velocity of the bubbles have been investigated. All the injected liquid drops did not necessarily boil even if they were heated above the saturation temperature. The probability of boiling of the liquid drops becomes larger as the temperature difference between two liquids becomes larger. The bubble generation frequency distributed around the mean elapsed time of the liquid drops. The larger temperature difference between two liquids presents sharper distribution. The radius of bubbles increased proportionally to the two-thirds power of the elapsed time and also to two-thirds power of the temperature difference. The liquid acceleration performance by bubbles increased as the bubble generation frequency distribution becomes sharpe. (Tai, I.)

Genetic and epigenetic control of plant heat responses

Directory of Open Access Journals (Sweden)

Junzhong eLiu

2015-04-01

Full Text Available Plants have evolved sophisticated genetic and epigenetic regulatory systems to respond quickly to unfavorable environmental conditions such as heat, cold, drought, and pathogen infections. In particular, heat greatly affects plant growth and development, immunity and circadian rhythm, and poses a serious threat to the global food supply. According to temperatures exposing, heat can be usually classified as warm ambient temperature (about 22-27℃, high temperature (27-30℃ and extremely high temperature (37-42℃, also known as heat stress for the model plant Arabidopsis thaliana. The genetic mechanisms of plant responses to heat have been well studied, mainly focusing on elevated ambient temperature-mediated morphological acclimation and acceleration of flowering, modulation of plant immunity and circadian clock by high temperatures, and thermotolerance to heat stress. Recently, great progress has been achieved on epigenetic regulation of heat responses, including DNA methylation, histone modifications, histone variants, ATP-dependent chromatin remodeling, histone chaperones, small RNAs, long non-coding RNAs and other undefined epigenetic mechanisms. These epigenetic modifications regulate the expression of heat-responsive genes and function to prevent heat-related damage. This review focuses on recent progresses regarding the genetic and epigenetic control of heat responses in plants, and pays more attention to the role of the major epigenetic mechanisms in plant heat responses. Further research perspectives are also discussed.

First muon acceleration using a radio-frequency accelerator

Directory of Open Access Journals (Sweden)

S. Bae

2018-05-01

Full Text Available Muons have been accelerated by using a radio-frequency accelerator for the first time. Negative muonium atoms (Mu^{-}, which are bound states of positive muons (μ^{+} and two electrons, are generated from μ^{+}’s through the electron capture process in an aluminum degrader. The generated Mu^{-}’s are initially electrostatically accelerated and injected into a radio-frequency quadrupole linac (RFQ. In the RFQ, the Mu^{-}’s are accelerated to 89 keV. The accelerated Mu^{-}’s are identified by momentum measurement and time of flight. This compact muon linac opens the door to various muon accelerator applications including particle physics measurements and the construction of a transmission muon microscope.

Enhanced Surface Warming and Accelerated Snow Melt in the Himalayas and Tibetan Plateau Induced by Absorbing Aerosols

Science.gov (United States)

Lau, William K.; Kim, Maeng-Ki; Kim, Kyu-Myong; Lee, Woo-Seop

2010-01-01

Numerical experiments with the NASA finite-volume general circulation model show that heating of the atmosphere by dust and black carbon can lead to widespread enhanced warming over the Tibetan Plateau (TP) and accelerated snow melt in the western TP and Himalayas. During the boreal spring, a thick aerosol layer, composed mainly of dust transported from adjacent deserts and black carbon from local emissions, builds up over the Indo-Gangetic Plain, against the foothills of the Himalaya and the TP. The aerosol layer, which extends from the surface to high elevation (approx.5 km), heats the mid-troposphere by absorbing solar radiation. The heating produces an atmospheric dynamical feedback the so-called elevated-heat-pump (EHP) effect, which increases moisture, cloudiness, and deep convection over northern India, as well as enhancing the rate of snow melt in the Himalayas and TP. The accelerated melting of snow is mostly confined to the western TP, first slowly in early April and then rapidly from early to mid-May. The snow cover remains reduced from mid-May through early June. The accelerated snow melt is accompanied by similar phases of enhanced warming of the atmosphere-land system of the TP, with the atmospheric warming leading the surface warming by several days. Surface energy balance analysis shows that the short-wave and long-wave surface radiative fluxes strongly offset each other, and are largely regulated by the changes in cloudiness and moisture over the TP. The slow melting phase in April is initiated by an effective transfer of sensible heat from a warmer atmosphere to land. The rapid melting phase in May is due to an evaporation-snow-land feedback coupled to an increase in atmospheric moisture over the TP induced by the EHP effect.

Enhanced surface warming and accelerated snow melt in the Himalayas and Tibetan Plateau induced by absorbing aerosols

International Nuclear Information System (INIS)

Lau, William K M; Kim, Maeng-Ki; Lee, Woo-Seop; Kim, Kyu-Myong

2010-01-01

Numerical experiments with the NASA finite-volume general circulation model show that heating of the atmosphere by dust and black carbon can lead to widespread enhanced warming over the Tibetan Plateau (TP) and accelerated snow melt in the western TP and Himalayas. During the boreal spring, a thick aerosol layer, composed mainly of dust transported from adjacent deserts and black carbon from local emissions, builds up over the Indo-Gangetic Plain, against the foothills of the Himalaya and the TP. The aerosol layer, which extends from the surface to high elevation (∼5 km), heats the mid-troposphere by absorbing solar radiation. The heating produces an atmospheric dynamical feedback-the so-called elevated-heat-pump (EHP) effect, which increases moisture, cloudiness, and deep convection over northern India, as well as enhancing the rate of snow melt in the Himalayas and TP. The accelerated melting of snow is mostly confined to the western TP, first slowly in early April and then rapidly from early to mid-May. The snow cover remains reduced from mid-May through early June. The accelerated snow melt is accompanied by similar phases of enhanced warming of the atmosphere-land system of the TP, with the atmospheric warming leading the surface warming by several days. Surface energy balance analysis shows that the short-wave and long-wave surface radiative fluxes strongly offset each other, and are largely regulated by the changes in cloudiness and moisture over the TP. The slow melting phase in April is initiated by an effective transfer of sensible heat from a warmer atmosphere to land. The rapid melting phase in May is due to an evaporation-snow-land feedback coupled to an increase in atmospheric moisture over the TP induced by the EHP effect.

Acceleration Modes and Transitions in Pulsed Plasma Accelerators

Science.gov (United States)

Polzin, Kurt A.; Greve, Christine M.

2018-01-01

Pulsed plasma accelerators typically operate by storing energy in a capacitor bank and then discharging this energy through a gas, ionizing and accelerating it through the Lorentz body force. Two plasma accelerator types employing this general scheme have typically been studied: the gas-fed pulsed plasma thruster and the quasi-steady magnetoplasmadynamic (MPD) accelerator. The gas-fed pulsed plasma accelerator is generally represented as a completely transient device discharging in approximately 1-10 microseconds. When the capacitor bank is discharged through the gas, a current sheet forms at the breech of the thruster and propagates forward under a j (current density) by B (magnetic field) body force, entraining propellant it encounters. This process is sometimes referred to as detonation-mode acceleration because the current sheet representation approximates that of a strong shock propagating through the gas. Acceleration of the initial current sheet ceases when either the current sheet reaches the end of the device and is ejected or when the current in the circuit reverses, striking a new current sheet at the breech and depriving the initial sheet of additional acceleration. In the quasi-steady MPD accelerator, the pulse is lengthened to approximately 1 millisecond or longer and maintained at an approximately constant level during discharge. The time over which the transient phenomena experienced during startup typically occur is short relative to the overall discharge time, which is now long enough for the plasma to assume a relatively steady-state configuration. The ionized gas flows through a stationary current channel in a manner that is sometimes referred to as the deflagration-mode of operation. The plasma experiences electromagnetic acceleration as it flows through the current channel towards the exit of the device. A device that had a short pulse length but appeared to operate in a plasma acceleration regime different from the gas-fed pulsed plasma

Observations of transverse ion acceleration in the topside auroral ionosphere

International Nuclear Information System (INIS)

Garbe, G.P.; Arnoldy, R.L.; Moore, T.E.; Kintner, P.M.; Vago, J.L.

1992-01-01

Data obtained from a sounding rocket flight which reached an apogee of 927 km and passed through several auroral arcs are reported. During portions of the flight when the rocket was not in an energetic auroral structure, the ion data are fit to a Maxwellian function which yields the plasma parameters. Throughout the middle portion of the flight when above 700 km altitude, ion distributions having a superthermal tail were measured. These ion distributions generally coexisted with a cold thermal core distribution and peaked at pitch angles slightly greater than 90 degree, which identifies them as conic distributions. These ions can be modeled using a bi-Maxwellian distribution function with a perpendicular (to B) temperature about 10 times greater than the parallel temperature of 0.15 eV. When the rocket was immersed in energetic auroral electron precipitation, two other ion distributions were observed. Transversely accelerated ions which represented bulk heating of the ambient population were observed. Transversely accelerated ions which represented bulk heating of the ambient population were observed continuously in these arcs. The characteristic perpendicular energy of the transversely bulk heated ions reached as high as 3 eV compared to typically less than 0.4 eV during nonauroral times. Cold ions flowing down the magnetic field were also continuously observed when the rocket was immersed in auroral electron precipitation and had downward speeds between 3 and 5 km/s. If one balances electric and collisional forces, these speeds translate to an electric field pointing into the atmosphere of magnitude 0.01 mV/m. A close correlation between auroral electron precipitation, measured electrostatic oxygen cyclotron waves, cold downflowing ions and transversely bulk heated ions will be shown

Radiological and economic impact of decommissioning charged particle accelerators

International Nuclear Information System (INIS)

Sonck, M.; Buls, N.; Hermanne, A.; Eggermont, G.

2000-01-01

To evaluate the real radiological and economic consequences of future dismantling of particle accelerators, only insufficient information was available in literature or even at the individual accelerator facilities themselves. DGXI of the European Commission hence launched a project with focus on gathering quantitative and scientifically sound data on the number of accelerators in the EU, on the status of activation of the different facilities, on the awareness of the possible problems at dismantling and on cost evacuations for full scale decommissioning. The project was granted to the VUB with subcontracts to NIRAS/ONDRAF, MAN and CEA-Saclay. With the replies received to an extensive questionnaire, a database was set up with the necessary data for evaluating the decommissioning problems to be expected at the different facilities. From this database three accelerators were chosen as reference cases (VUB medium energy cyclotron, IRMM 200 MeV electron linear accelerator and the 6 GeV proton synchrotron Saturne in Saclay). Extensive sampling of their concrete shieldings (more than 200 drill cores) and metal parts of accelerator and infrastructure, followed by accurate γ-spectrometric analysis and custom designed 3D interpolation, yield data on the 3D distribution of the activity in the different rooms of the installations. In addition to the γ-spectrometric analysis, an analysis of the tritium content of the concrete was performed by measuring the water liberated from heating ground concrete samples. These specific activity distributions allow evaluation of both immediate and deferred decommissioning costs using different scenarios (different clearance levels, different waste management prices, different labor costs and different decommissioning techniques) based on real situations in France, Germany and Great Britain. Several important conclusions and recommendations with respect to decommissioning both existing and future accelerator facilities will be presented

On radiation heating of superconducting magnets of the accelerating-storage complex

International Nuclear Information System (INIS)

Maslov, M.A.; Mokhov, N.V.

1981-01-01

To analyze regularities of energy release formation in a superconducting winding (SCW) of superconducting magnets (SCM) of the IHEP accelerating-storage facility the energy release values in the SCM when 400-3000 GeV proton beam incidence onto the SCM vacuum chamber are calculated. Two SCM modifications (a dipole one and a quadrupole one) and two modes of irradiation (uniform irradiation along the SCM azimuth and length and a thin beam incidence uniform along the SCM length) are considered. It is shown that for the SCM with the 26 cm aperture at the 1 mrad angle of incidence 25% of the initial proton energy is released [ru

Hot target assembly at 14 UD Pelletron Accelerator Facility, BARC- TIFR, Mumbai

International Nuclear Information System (INIS)

Sharma, S.C.; Ramjilal; Ninawe, N.G.; Bhagwat, P.V.; Ahmeabadhai, P.; Kain, V.

2005-01-01

BARC-TIFR 14 UD Pelletron Accelerator Facility at Mumbai is operational since 1989 with progressively increased efficiency. The accelerator has been serving as major facility for heavy ion based research in India. There is an increased demand for high current proton beam, especially on heated targets for reactor physics based experiments. A proton beam setup is commissioned in the tower area of the existing facility itself, which provide proton beam of energy 2 MeV to 26 MeV with maximum 3 μA current. This setup is being used to produce radioisotopes and tracer packets. Proton beam of few MeV in μA current range is also needed to study radiation effects on metals at higher temperature, for use in reactors. For this purpose a hot target assembly has been designed and is being currently used at the Pelletron Accelerator

Accelerator development

International Nuclear Information System (INIS)

Anon.

1975-01-01

Because the use of accelerated heavy ions would provide many opportunities for new and important studies in nuclear physics and nuclear chemistry, as well as other disciplines, both the Chemistry and Physics Divisions are supporting the development of a heavy-ion accelerator. The design of greatest current interest includes a tandem accelerator with a terminal voltage of approximately 25 MV injecting into a linear accelerator with rf superconducting resonators. This combined accelerator facility would be capable of accelerating ions of masses ranging over the entire periodic table to an energy corresponding to approximately 10 MeV/nucleon. This approach, as compared to other concepts, has the advantages of lower construction costs, lower operating power, 100 percent duty factor, and high beam quality (good energy resolution, good timing resolution, small beam size, and small beam divergence). The included sections describe the concept of the proposed heavy-ion accelerator, and the development program aiming at: (1) investigation of the individual questions concerning the superconducting accelerating resonators; (2) construction and testing of prototype accelerator systems; and (3) search for economical solutions to engineering problems. (U.S.)

Maximal heat loading of electrostatic deflector's septum at the cyclotron

International Nuclear Information System (INIS)

Arzumanov, A.; Borissenko, A.

2002-01-01

An electrostatic deflector is used for extraction of accelerated particles at the isochronous cyclotron U-150 (Institute of Nuclear Physics, Kazakhstan). Efficiency of beam extraction depends on a set of factors. Decisive is heat state of the septum and essentially beam extraction is limited by beam power dissipation on the deflector. Due to the works carried on for radioisotope production, determination of septum's maximal heat loading, optimization of the septum's geometry represent the interest. Maximum heat loading of deflector's septum and it's dependence on septum's geometry and thermal-physical properties of septum's material are presented in the paper as result of numerical calculation. The obtained results are discussed

Accelerator Technology: Geodesy and Alignment for Particle Accelerators

CERN Document Server

Missiaen, D

2013-01-01

This document is part of Subvolume C 'Accelerators and Colliders' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the the Section '8.9 Geodesy and Alignment for Particle Accelerators' of the Chapter '8 Accelerator Technology' with the content: 8.9 Geodesy and Alignment for Particle Accelerators 8.9.1 Introduction 8.9.2 Reference and Co-ordinate Systems 8.9.3 Definition of the Beam Line on the Accelerator Site 8.9.4 Geodetic Network 8.9.5 Tunnel Preliminary Works 8.9.6 The Alignment References 8.9.7 Alignment of Accelerator Components 8.9.8 Permanent Monitoring and Remote Alignment of Low Beta Quadrupoles 8.9.9 Alignment of Detector Components

Effects of dimensionality and laser polarization on kinetic simulations of laser-ion acceleration in the transparency regime

Science.gov (United States)

Stark, David; Yin, Lin; Albright, Brian; Guo, Fan

2017-10-01

The often cost-prohibitive nature of three-dimensional (3D) kinetic simulations of laser-plasma interactions has resulted in heavy use of two-dimensional (2D) simulations to extract physics. However, depending on whether the polarization is modeled as 2D-S or 2D-P (laser polarization in and out of the simulation plane, respectively), different results arise. In laser-ion acceleration in the transparency regime, VPIC particle-in-cell simulations show that 2D-S and 2D-P capture different physics that appears in 3D simulations. The electron momentum distribution is virtually two-dimensional in 2D-P, unlike the more isotropic distributions in 2D-S and 3D, leading to greater heating in the simulation plane. As a result, target expansion time scales and density thresholds for the onset of relativistic transparency differ dramatically between 2D-S and 2D-P. The artificial electron heating in 2D-P exaggerates the effectiveness of target-normal sheath acceleration (TNSA) into its dominant acceleration mechanism, whereas 2D-S and 3D both have populations accelerated preferentially during transparency to higher energies than those of TNSA. Funded by the LANL Directed Research and Development Program.

High Energy Density Physics and Exotic Acceleration Schemes

International Nuclear Information System (INIS)

Cowan, T.; Colby, E.

2005-01-01

The High Energy Density and Exotic Acceleration working group took as our goal to reach beyond the community of plasma accelerator research with its applications to high energy physics, to promote exchange with other disciplines which are challenged by related and demanding beam physics issues. The scope of the group was to cover particle acceleration and beam transport that, unlike other groups at AAC, are not mediated by plasmas or by electromagnetic structures. At this Workshop, we saw an impressive advancement from years past in the area of Vacuum Acceleration, for example with the LEAP experiment at Stanford. And we saw an influx of exciting new beam physics topics involving particle propagation inside of solid-density plasmas or at extremely high charge density, particularly in the areas of laser acceleration of ions, and extreme beams for fusion energy research, including Heavy-ion Inertial Fusion beam physics. One example of the importance and extreme nature of beam physics in HED research is the requirement in the Fast Ignitor scheme of inertial fusion to heat a compressed DT fusion pellet to keV temperatures by injection of laser-driven electron or ion beams of giga-Amp current. Even in modest experiments presently being performed on the laser-acceleration of ions from solids, mega-amp currents of MeV electrons must be transported through solid foils, requiring almost complete return current neutralization, and giving rise to a wide variety of beam-plasma instabilities. As keynote talks our group promoted Ion Acceleration (plenary talk by A. MacKinnon), which historically has grown out of inertial fusion research, and HIF Accelerator Research (invited talk by A. Friedman), which will require impressive advancements in space-charge-limited ion beam physics and in understanding the generation and transport of neutralized ion beams. A unifying aspect of High Energy Density applications was the physics of particle beams inside of solids, which is proving to

Accelerated Testing of UH-60 Viscous Bearings for Degraded Grease Fault

Science.gov (United States)

Dykas, Brian; Hood, Adrian; Krantz, Timothy; Klemmer, Marko

2015-01-01

An accelerated aging investigation of critical aviation bearings lubricated with MIL-PRF- 81322 grease was conducted to derive an understanding of the mechanisms of grease degradation and loss of lubrication over time. The current study focuses on UH-60 Black Hawk viscous damper bearings supporting the tail rotor driveshaft, which were subjected to more than 5800 hours of testing in a heated environment to accelerate the deterioration of the grease. The mechanism of grease degradation is a reduction in the oil/thickener ratio rather than the expected chemical degradation of grease constituents. Over the course of testing, vibration and temperature monitoring of bearings was conducted and trends for failing bearings are presented.

Electron Acceleration in the Field-reversed Configuration (FRC) by Slowly Rotation Odd-parity Magnetic Fields (RMFo)

International Nuclear Information System (INIS)

Glasser, A.H.; Cohen, S.A.

2001-01-01

The trajectories of individual electrons are studied numerically in a 3D, prolate, FRC [field-reversed configuration] equilibrium magnetic geometry with added small-amplitude, slowly rotating, odd-parity magnetic fields (RMFos). RMFos cause electron heating by toroidal acceleration near the O-point line and by field-parallel acceleration away from it, both followed by scattering from magnetic-field inhomogeneities. Electrons accelerated along the O-point line move antiparallel to the FRC's current and attain average toroidal angular speeds near that of the RMFo, independent of the sense of RMFo rotation. A conserved transformed Hamiltonian, dependent on electron energy and RMFo sense, controls electron flux-surface coordinate

ATF1 Modulates the Heat Shock Response by Regulating the Stress-Inducible Heat Shock Factor 1 Transcription Complex

Science.gov (United States)

Takii, Ryosuke; Fujimoto, Mitsuaki; Tan, Ke; Takaki, Eiichi; Hayashida, Naoki; Nakato, Ryuichiro; Shirahige, Katsuhiko

2014-01-01

The heat shock response is an evolutionally conserved adaptive response to high temperatures that controls proteostasis capacity and is regulated mainly by an ancient heat shock factor (HSF). However, the regulation of target genes by the stress-inducible HSF1 transcription complex has not yet been examined in detail in mammalian cells. In the present study, we demonstrated that HSF1 interacted with members of the ATF1/CREB family involved in metabolic homeostasis and recruited them on the HSP70 promoter in response to heat shock. The HSF1 transcription complex, including the chromatin-remodeling factor BRG1 and lysine acetyltransferases p300 and CREB-binding protein (CBP), was formed in a manner that was dependent on the phosphorylation of ATF1. ATF1-BRG1 promoted the establishment of an active chromatin state and HSP70 expression during heat shock, whereas ATF1-p300/CBP accelerated the shutdown of HSF1 DNA-binding activity during recovery from acute stress, possibly through the acetylation of HSF1. Furthermore, ATF1 markedly affected the resistance to heat shock. These results revealed the unanticipated complexity of the primitive heat shock response mechanism, which is connected to metabolic adaptation. PMID:25312646

Proton acceleration experiments and warm dense matter research using high power lasers

Energy Technology Data Exchange (ETDEWEB)

Roth, M; Alber, I; Guenther, M; Harres, K [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Bagnoud, V [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Brown, C R D [Plasma Physics Group, Imperial College London, SW7 2BZ (United Kingdom); Clarke, R; Heathcote, R; Li, B [STFC, Rutherford Appleton Laboratory (RAL), Chilton, Didcot, OX14 OQX (United Kingdom); Daido, H [Photo Medical Research Center, JAEA, Kizugawa-City, Kyoto 619-0215 (Japan); Fernandez, J; Flippo, K; Gaillard, S; Gauthier, C [Los Alamos National Laboratory (LANL), Los Alamos, NM 87545 (United States); Geissel, M [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Glenzer, S; Kritcher, A; Kugland, N; LePape, S [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Gregori, G, E-mail: markus.roth@physik.tu-darmstadt.d [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom)

2009-12-15

The acceleration of intense proton and ion beams by ultra-intense lasers has matured to a point where applications in basic research and technology are being developed. Crucial for harvesting the unmatched beam parameters driven by the relativistic electron sheath is the precise control of the beam. In this paper we report on recent experiments using the PHELIX laser at GSI, the VULCAN laser at RAL and the TRIDENT laser at LANL to control and use laser accelerated proton beams for applications in high energy density research. We demonstrate efficient collimation of the proton beam using high field pulsed solenoid magnets, a prerequisite to capture and transport the beam for applications. Furthermore, we report on two campaigns to use intense, short proton bunches to isochorically heat solid targets up to the warm dense matter state. The temporal profile of the proton beam allows for rapid heating of the target, much faster than the hydrodynamic response time thereby creating a strongly coupled plasma at solid density. The target parameters are then probed by x-ray Thomson scattering to reveal the density and temperature of the heated volume. This combination of two powerful techniques developed during the past few years allows for the generation and investigation of macroscopic samples of matter in states present in giant planets or the interior of the earth.

Proton acceleration experiments and warm dense matter research using high power lasers

International Nuclear Information System (INIS)

Roth, M; Alber, I; Guenther, M; Harres, K; Bagnoud, V; Brown, C R D; Clarke, R; Heathcote, R; Li, B; Daido, H; Fernandez, J; Flippo, K; Gaillard, S; Gauthier, C; Geissel, M; Glenzer, S; Kritcher, A; Kugland, N; LePape, S; Gregori, G

2009-01-01

The acceleration of intense proton and ion beams by ultra-intense lasers has matured to a point where applications in basic research and technology are being developed. Crucial for harvesting the unmatched beam parameters driven by the relativistic electron sheath is the precise control of the beam. In this paper we report on recent experiments using the PHELIX laser at GSI, the VULCAN laser at RAL and the TRIDENT laser at LANL to control and use laser accelerated proton beams for applications in high energy density research. We demonstrate efficient collimation of the proton beam using high field pulsed solenoid magnets, a prerequisite to capture and transport the beam for applications. Furthermore, we report on two campaigns to use intense, short proton bunches to isochorically heat solid targets up to the warm dense matter state. The temporal profile of the proton beam allows for rapid heating of the target, much faster than the hydrodynamic response time thereby creating a strongly coupled plasma at solid density. The target parameters are then probed by x-ray Thomson scattering to reveal the density and temperature of the heated volume. This combination of two powerful techniques developed during the past few years allows for the generation and investigation of macroscopic samples of matter in states present in giant planets or the interior of the earth.

Numerical and experimental investigations of coupled electromagnetic and thermal fields in superconducting accelerator magnets

International Nuclear Information System (INIS)

Mierau, Anna

2013-01-01

The new international facility for antiproton and ion research FAIR will be built in Darmstadt (Germany). The existing accelerator facility of GSI Helmholtzzentrum for Heavy Ion Research will serve as a pre-accelerator for the new facility. FAIR will provide high-energy antiproton and ion beams with unprecedented intensity and quality for fundamental research of states of matter and the evolution of the universe. The central component of FAIR's accelerator and storage rings complex is a double-ring accelerator consisting of two heavy ion synchrotrons SIS100 and SIS300. The SIS100 is the primary accelerator of FAIR. The desired beam properties of SIS100 require a design of the machine much more challenging than the conventional design of existing proton and ion synchrotrons. The key technical components of each synchrotron are the special electromagnets, which allow guiding the charged particles on their orbits in the synchrotron during the acceleration processes. For a stable operation of the SIS100's the magnets have to produce extremely homogeneous magnetic fields. Furthermore, the SIS100 high-intensity ion beam modes, for example with U 28+ ions, require an ultra-high vacuum in the beam pipe of the synchrotron, which can be generated effectively only at low temperatures below 15 K. Due to the field quality requirements for the magnets, the properties of the dynamic vacuum in the beam pipe but also in order to minimise future operating costs, fast ramped superconducting magnets will be used to guide the beam in SIS100. These magnets have been developed at GSI within the framework of the FAIR project. Developing a balanced design of a superconducting accelerator magnet requires a sound understanding of the interaction between its thermal and electromagnetic fields. Of special importance in this case are the magnetic field properties such as the homogeneity of the static magnetic field in the aperture of the magnet, and the dynamic heat losses of the whole magnet

2014 CERN Accelerator Schools: Plasma Wake Acceleration

CERN Multimedia

2014-01-01

A specialised school on Plasma Wake Acceleration will be held at CERN, Switzerland from 23-29 November, 2014.   This course will be of interest to staff and students in accelerator laboratories, university departments and companies working in or having an interest in the field of new acceleration techniques. Following introductory lectures on plasma and laser physics, the course will cover the different components of a plasma wake accelerator and plasma beam systems. An overview of the experimental studies, diagnostic tools and state of the art wake acceleration facilities, both present and planned, will complement the theoretical part. Topical seminars and a visit of CERN will complete the programme. Further information can be found at: http://cas.web.cern.ch/cas/PlasmaWake2014/CERN-advert.html http://indico.cern.ch/event/285444/

Modelling of Quench Limit for Steady State Heat Deposits in LHC Magnets

CERN Document Server

Bocian, D; Siemko, A

2008-01-01

A quench, the transition of a conductor from the superconducting to the normal conducting state, occurs irreversibly in the accelerator magnets if one of the three parameters: temperature, magnetic field or current density exceeds a critical value. Energy deposited in the superconductor by the particle beams provokes quenches detrimental for the accelerator operation. In particular if particles impacting on the vacuum chamber and their secondary showers depose energy in the magnet coils. The Large Hadron Collider (LHC) nominal beam intensity is 3.2 ldr 10^14 protons. A quench occurs if a fraction of the order of 10^7 protons per second is lost locally. A network model is used to simulate the thermodynamic behaviour of the magnets. The heat flow in the network model was validated with measurements performed in the CERN magnet test facility. A steady state heat flow was introduced in the coil by using the quench heaters implemented in the LHC magnets. The value of the heat source current is determined by the ne...

Virtual Accelerator for Accelerator Optics Improvement

CERN Document Server

Yan Yi Ton; Decker, Franz Josef; Ecklund, Stanley; Irwin, John; Seeman, John; Sullivan, Michael K; Turner, J L; Wienands, Ulrich

2005-01-01

Through determination of all quadrupole strengths and sextupole feed-downs by fitting quantities derivable from precision orbit measurement, one can establish a virtual accelerator that matches the real accelerator optics. These quantities (the phase advances, the Green's functions, and the coupling eigen-plane ellipses tilt angles and axis ratios) are obtained by analyzing turn-by-turn Beam Position Monitor (BPM) data with a model-independent analysis (MIA). Instead of trying to identify magnet errors, a limited number of quadrupoles are chosen for optimized strength adjustment to improve the virtual accelerator optics and then applied to the real accelerator accordingly. These processes have been successfully applied to PEP-II rings for beta beating fixes, phase and working tune adjustments, and linear coupling reduction to improve PEP-II luminosity.

Application of the laser induced fluorescence to the investigation of highly magnetized plasmas, heated by ion cyclotron resonance; Fluorescence induite par laser sur des plasmas fortement magnetises, chauffes par resonnance cyclotron ionique

Energy Technology Data Exchange (ETDEWEB)

Pailloux, A. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. des Procedes d`Enrichissement]|[Universite Louis Pasteur, 67 - Strasbourg (France)

1997-12-31

This work has been achieved in the frame of isotopic separation studies by in cyclotron resonance. For this purpose, in a highly magnetized (2 to 3 Tesla) and non-collisional (10{sup 12} ions/cm{sup 3}) plasma, composed of metallic ions, a wave near the ion cyclotron frequency is thrown in order to heat selectively a given species. A laser induced fluorescence (LIP) has been developed on barium and gadolinium plasmas. The Larmor gyration of ions greatly modifies the interaction, which has been modelled through the time-dependent Schroedinger equation. The obtained excitation probably has been integrated over all the ions excited in the measurement volume in order to check that the LIF still leads to the distribution function of ion velocities. The influence of the Larmor motion of ions on the spectral distribution of LIF has been derived both theoretically and experimentally. The LIF diagnostics has been achieved with a dye O`ring laser. The barium ion has been excited on the transition 6142 angstrom, using rhodamine 6G dye, and the gadolinium ion on the pseudo-triplet 3861 angstrom, using exalite dye. Data treatment has been developed taking into account the Zeeman effect and the different heating of isotopes. The ionic temperature (from 1 eV to some hundreds eV) has been measured as a function of radiofrequency heating. Our experimental results are in good agreement with the selective heating theory. Also, the ion velocity distribution function has been found locally Maxwellian. And the behaviour of the plasma has been studied as a function of control parameters of the plasma source. (author) 62 refs.

Dehydration of sodium carbonate monohydrate with indirect microwave heating

International Nuclear Information System (INIS)

Seyrankaya, Abdullah; Ozalp, Baris

2006-01-01

In this study, dehydration of sodium carbonate monohydrate (Na 2 CO 3 .H 2 O) (SCM) in microwave (MW) field with silicon carbide (SiC) as an indirect heating medium was investigated. SCM samples containing up to 3% free moisture were placed in the microwave oven. The heating experiments showed that SCM is a poor microwave energy absorber for up to 6 min of irradiation at an 800 W of microwave power. The heat for SCM calcination is provided by SiC which absorbs microwave. The monohydrate is then converted to anhydrous sodium carbonate on the SiC plate by calcining, i.e. by removing the crystal water through heating of the monohydrate temperatures of over 120 deg. C. The calcination results in a solid phase recrystallization of the monohydrate into anhydrate. In the microwave irradiation process, dehydration of SCM in terms of indirect heating can be accelerated by increasing the microwave field power

Theory of factors limiting high gradient operation of warm accelerating structures

Energy Technology Data Exchange (ETDEWEB)

Nusinovich, Gregory S. [University of Maryland; Antonsen, Thomas M. [University of Maryland; Kishek, Rami [University of Maryland

2014-07-25

This final report summarizes the research performed during the time period from 8/1/2010 to 7/31/2013. It consists of two parts describing our studies in two directions: (a) analysis of factors limiting operation of dielectric-loaded accelerating (DLA) structures where the main problem is the occurrence of multipactor on dielectric surfaces, and (b) studies of effects associated with either RF magnetic or RF electric fields which may cause the RF breakdown in high-gradient metallic accelerating structures. In the studies of DLA structures, at least, two accomplishments should be mentioned: the development of a 3D non-stationary, self-consistent code describing the multipactor phenomena and yielding very good agreement with some experimental data obtained in joint ANL/NRL experiments. In the metallic structures, such phenomena as the heating and melting of micro-particles (metallic dust) by RF electric and magnetic fields in single-shot and rep-rate regimes is analyzed. Also, such processes in micro-protrusions on the structure surfaces as heating and melting due to the field emitted current and the Nottingham effect are thoroughly investigated with the account for space charge of emitted current on the field emission from the tip.

Heating of toroidal plasmas by neutral injection

International Nuclear Information System (INIS)

Stix, T.H.

1971-08-01

This paper presents a brief review of the physics of ion acceleration, charge exchange and ionization, trajectories for fast ions in toroidal magnetic fields, and fast-ion thermalization. The injection of fast atoms is found to be a highly competitive method both for heating present-day experimental toroidal plasmas and for bringing full-scale toroidal CTR plasmas to low-density ignition. 13 refs., 9 figs

Experimental study of pulsed heating of electromagnetic cavities

International Nuclear Information System (INIS)

Pritzkau, D.P.; Menegat, A.; Siemann, R.H.

1997-01-01

An experiment to study the effects of pulsed heating in electromagnetic cavities will be performed. Pulsed heating is believed to be the limiting mechanism of high acceleration gradients at short wavelengths. A cylindrical cavity operated in the TE 011 mode at a frequency of 11.424 GHz will be used. A klystron will be used to supply a peak input power of 20 MW with a pulse length of 1.5 μs. The temperature response of the cavity will be measured by a second waveguide designed to excite a TE 012 mode in the cavity with a low-power CW signal at a frequency of 17.8 GHz. The relevant theory of pulsed heating will be discussed and the results from cold-testing the structure will be presented

Dielectric-Lined High-Gradient Accelerator Structure

Energy Technology Data Exchange (ETDEWEB)

Jay L. Hirshfield

2012-04-24

operating at 30 GHz. It was shown that the ratio of maximum surface electric field to accelerating field at the metal wall is only 0.35-0.4 for DLA, much smaller than the value 2.2 for HDS; and the ratio of surface magnetic field to accelerating field is 3.0 mA/V for DLA, compared with 3.45 mA/V for HDS. These values bode well for DLA in helping to avoid breakdown and to reducing pulsed surface heating and fatigue. The shunt impedance is found to be 160-175 M{Omega}/m for DLA, as compared to 99 M{Omega}/m for HDS. Conclusions are reached from this project that CVD diamond appears promising as a dielectric with a high threshold for RF breakdown, and that rectangular accelerator structures can be devised using planar CVD diamond elements that could be operated at higher acceleration gradients with low probability of RF breakdown, as compared with corresponding all-metallic structures.

Dielectric-Lined High-Gradient Accelerator Structure

International Nuclear Information System (INIS)

Hirshfield, Jay L.

2012-01-01

GHz. It was shown that the ratio of maximum surface electric field to accelerating field at the metal wall is only 0.35-0.4 for DLA, much smaller than the value 2.2 for HDS; and the ratio of surface magnetic field to accelerating field is 3.0 mA/V for DLA, compared with 3.45 mA/V for HDS. These values bode well for DLA in helping to avoid breakdown and to reducing pulsed surface heating and fatigue. The shunt impedance is found to be 160-175 M(Omega)/m for DLA, as compared to 99 M(Omega)/m for HDS. Conclusions are reached from this project that CVD diamond appears promising as a dielectric with a high threshold for RF breakdown, and that rectangular accelerator structures can be devised using planar CVD diamond elements that could be operated at higher acceleration gradients with low probability of RF breakdown, as compared with corresponding all-metallic structures.

Thermal efficiency and acceleration benefits of cross SAGD (XSAGD)

Energy Technology Data Exchange (ETDEWEB)

Stalder, J.L. [ConocoPhillips Canada Resources Corp., Calgary, AB (Canada)

2008-10-15

Steam assisted gravity drainage (SAGD) is suitable for the thermal recovery of bitumen from Alberta's Athabasca oil sands. The oil mobilization process occurs at the periphery of the steam chamber where heat is transferred to the reservoir rock and bitumen. However, in low pressure shallow depth situations, SAGD recovery of bitumen tends to slow significantly compared to higher pressure operation because the presence of dissolved gas can have a negative impact on steam chamber growth at lower pressure. Cross SAGD (XSAGD) is an alternative well arrangement similar to SAGD, but the wells are perpendicular to the producing wells with some type of restricted completion near the crossing points that limits short-circulating steam. This allows rapid communication between wells near the crossing points. This paper presented the results of a simulation study that was conducted to examine the impact of XSAGD performance of heat transfer between the liners in the horizontal wells and the surrounding reservoir. A pay thickness in the range of 10 to 40 m was considered as well as a constant injection pressure in the range of 1500 to 4500 kPa. The study showed that the lateral growth of the steam chamber and ultimate recovery is accelerated by the heat transfer between the perpendicular horizontal liners and the reservoir. The cumulative steam oil ratio for XSAGD is also reduced. However, heat transfer had little impact on the performance produced by the parallel arrangement of wells in classical SAGD. The ratio of surface area to volume of the steam chamber is typically greater for XSAGD than for SAGD after the steam chambers are well established. Although SAGD recovery is accelerated as pay thickness increases, XSAGD recovery time is not influenced by pay thickness. For pay thinner than 20 m, XSAGD recovery is much faster than SAGD recovery, but is approximately the same for pay 40 m or thicker. 6 refs., 1 tab., 12 figs.

Analyzing radial acceleration with a smartphone acceleration sensor

Science.gov (United States)

Vogt, Patrik; Kuhn, Jochen

2013-03-01

This paper continues the sequence of experiments using the acceleration sensor of smartphones (for description of the function and the use of the acceleration sensor, see Ref. 1) within this column, in this case for analyzing the radial acceleration.

Power Transfer to plasma Coxial accelerator

International Nuclear Information System (INIS)

El-Aragi, G.M.; Soliman, H.M.; Masoud, M.M.

2000-01-01

The total power transfer from the condenser bank, to plasma coaxial accelerator device is theoretically studied by using the voltage equation of the entire circuit and applying impulse - linear momentum theorem. This total power represents a combination of (a) the power flowing to the external inductance, (b) the power flowing to the inductance of that part of electrode system between the breech and the momentary position of the plasma current sheath, (c) the power flowing in the annular space between the two coaxial electrodes, to form the magnetic field induction, (d) the power flowing to accelerate the initial mass, (e) the power flowing to accelerate the mass, which has been swept up into the plasma current sheath, (f) the power, which produces directed kinetic energy for the plasma current sheath, (g) the power, which produces internal energy in the plasma sheath, (h) the joule heating. The peak value of the total power = 6x10 8 watt at t=4 MUs, for maximum calculated discharge current = 110KA with a with a period of 34 us. Experimentally its equal to 3.5x10 8 watt at 7MUs and I 0 = 85KA. The energy flow to the coaxial discharge system has been evaluated theoretically and experimentally, E-MAX (CALCULATED)=5.92X10 2 J AT T = 5.5 MUs and E m ax (measured) = 3.54x10 2 joule at 7.5 MUs

Estimation of interfacial heat transfer coefficient in inverse heat conduction problems based on artificial fish swarm algorithm

Science.gov (United States)

Wang, Xiaowei; Li, Huiping; Li, Zhichao

2018-04-01

The interfacial heat transfer coefficient (IHTC) is one of the most important thermal physical parameters which have significant effects on the calculation accuracy of physical fields in the numerical simulation. In this study, the artificial fish swarm algorithm (AFSA) was used to evaluate the IHTC between the heated sample and the quenchant in a one-dimensional heat conduction problem. AFSA is a global optimization method. In order to speed up the convergence speed, a hybrid method which is the combination of AFSA and normal distribution method (ZAFSA) was presented. The IHTC evaluated by ZAFSA were compared with those attained by AFSA and the advanced-retreat method and golden section method. The results show that the reasonable IHTC is obtained by using ZAFSA, the convergence of hybrid method is well. The algorithm based on ZAFSA can not only accelerate the convergence speed, but also reduce the numerical oscillation in the evaluation of IHTC.

Accelerator breeder: a viable option for the production of nuclear fuels

International Nuclear Information System (INIS)

Grand, P.

1983-01-01

Despite the growing pains of the US nuclear power industry, our dependence on nuclear energy for the production of electricity and possibly process heat is likely to increase dramatically over the next few deacades. This statement dismisses fusion as being entirely too speculative to be practical within that time frame. Sometime, between the years 2000 and 2050, fissile material will be in short supply whether it is to fuel existing LWR's or to provide initial fuel inventory for FBR's. The accelerator breeder could produce the fuel shortfall predicted to occur during the first half of the 21st century. The accelerator breeder offers the only practical means today of producing, or breeding, large quantities of fissile fuel from fertile materials, albeit at high cost. Studies performed over the last few years at Chalk River Laboratory and at Brookhaven National Laboratory have demonstrated that the accelerator breeder is practical, technically feasible with state-of-the-art technology, and is economically competitive with any other proposed synthetic means of fissile fuel production. This paper gives the parameters of a nearly optimized accelerator-breeder system, then discusses the development needs, and the economics and institutional problems that this breeding concept faces

Single-phase liquid jet impingement heat transfer

International Nuclear Information System (INIS)

Webb, B.W.; Ma, C.F.

1995-01-01

Impinging liquid jets have been demonstrated to be an effective means of providing high heat/mass transfer rates in industrial transport processes. When a liquid jet strikes a surface, thin hydrodynamic and thermal boundary layers from in the region directly beneath due to the jet deceleration and the resulting increase in pressure. The flow is then forced to accelerate in a direction parallel to the target surface in what is termed the wall jet or parallel flow zone. The thickness of the hydrodynamic and thermal boundary layers in the stagnation region may be of the order of tens of micrometers. Consequently, very high heat/mass transfer coefficients exist in the stagnation zone directly under the jet. Transport coefficients characteristic of parallel flow prevail in the wall jet region. The high heat transfer coefficients make liquid jet impingement an attractive cooling option where high heat fluxes are the norm. Some industrial applications include the thermal treatment of metals, cooling of internal combustion engines, and more recently, thermal control of high-heat-dissipation electronic devices. Both circular and planar liquid jets have attracted research attention. 180 refs., 35 figs., 11 tabs

Investigation on copper alloy and titanium heat exchanger tubes behaviour in sea water service

International Nuclear Information System (INIS)

Casarini, G.; Bianchi, M.; Winkler, L.; Caspani, M.

1982-01-01

Because of the contradictory behaviour in service of some copper alloys used in heat exchangers cooled by sea water (Mediterranean Sea - North Africa), a comparative study on the behaviour of some tubular test samples was performed by means of accelerated test run ''in situ'' using two little heat exchangers supplied by Foster Wheeler Italiana. The aim of the investigation was to obtain quick and reliable information on optimizing the choise of the most suitable material for the construction of new heat exchangers

Ion acceleration from relativistic laser nano-target

Energy Technology Data Exchange (ETDEWEB)

Jung, Daniel

2012-01-06

Laser-ion acceleration has been of particular interest over the last decade for fundamental as well as applied sciences. Remarkable progress has been made in realizing laser-driven accelerators that are cheap and very compact compared with conventional rf-accelerators. Proton and ion beams have been produced with particle energies of up to 50 MeV and several MeV/u, respectively, with outstanding properties in terms of transverse emittance and current. These beams typically exhibit an exponentially decaying energy distribution, but almost all advanced applications, such as oncology, proton imaging or fast ignition, require quasimonoenergetic beams with a low energy spread. The majority of the experiments investigated ion acceleration in the target normal sheath acceleration (TNSA) regime with comparably thick targets in the {mu}m range. In this thesis ion acceleration is investigated from nm-scaled targets, which are partially produced at the University of Munich with thickness as low as 3 nm. Experiments have been carried out at LANL's Trident high-power and high-contrast laser (80 J, 500 fs, {lambda}=1054 nm), where ion acceleration with these nano-targets occurs during the relativistic transparency of the target, in the so-called Breakout afterburner (BOA) regime. With a novel high resolution and high dispersion Thomson parabola and ion wide angle spectrometer, thickness dependencies of the ions angular distribution, particle number, average and maximum energy have been measured. Carbon C{sup 6+} energies reached 650 MeV and 1 GeV for unheated and heated targets, respectively, and proton energies peaked at 75 MeV and 120 MeV for diamond and CH{sub 2} targets. Experimental data is presented, where the conversion efficiency into carbon C{sup 6+} (protons) is investigated and found to have an up to 10fold (5fold) increase over the TNSA regime. With circularly polarized laser light, quasi-monoenergetic carbon ions have been generated from the same nm-scaled foil

Community Petascale Project for Accelerator Science and Simulation: Advancing Computational Science for Future Accelerators and Accelerator Technologies

Energy Technology Data Exchange (ETDEWEB)

Spentzouris, P.; /Fermilab; Cary, J.; /Tech-X, Boulder; McInnes, L.C.; /Argonne; Mori, W.; /UCLA; Ng, C.; /SLAC; Ng, E.; Ryne, R.; /LBL, Berkeley

2011-11-14

The design and performance optimization of particle accelerators are essential for the success of the DOE scientific program in the next decade. Particle accelerators are very complex systems whose accurate description involves a large number of degrees of freedom and requires the inclusion of many physics processes. Building on the success of the SciDAC-1 Accelerator Science and Technology project, the SciDAC-2 Community Petascale Project for Accelerator Science and Simulation (ComPASS) is developing a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and laser/plasma acceleration modelling. ComPASS is providing accelerator scientists the tools required to enable the necessary accelerator simulation paradigm shift from high-fidelity single physics process modeling (covered under SciDAC1) to high-fidelity multiphysics modeling. Our computational frameworks have been used to model the behavior of a large number of accelerators and accelerator R&D experiments, assisting both their design and performance optimization. As parallel computational applications, the ComPASS codes have been shown to make effective use of thousands of processors. ComPASS is in the first year of executing its plan to develop the next-generation HPC accelerator modeling tools. ComPASS aims to develop an integrated simulation environment that will utilize existing and new accelerator physics modules with petascale capabilities, by employing modern computing and solver technologies. The ComPASS vision is to deliver to accelerator scientists a virtual accelerator and virtual prototyping modeling environment, with the necessary multiphysics, multiscale capabilities. The plan for this development includes delivering accelerator modeling applications appropriate for each stage of the ComPASS software evolution. Such applications are already being used to address challenging problems in accelerator design and optimization. The ComPASS organization

Accelerator Service

International Nuclear Information System (INIS)

Champelovier, Y.; Ferrari, M.; Gardon, A.; Hadinger, G.; Martin, J.; Plantier, A.

1998-01-01

Since the cessation of the operation of hydrogen cluster accelerator in July 1996, four electrostatic accelerators were in operation and used by the peri-nuclear teams working in multidisciplinary collaborations. These are the 4 MV Van de Graaff accelerator, 2,5 MV Van de Graaff accelerator, 400 kV ion implanter as well as the 120 kV isotope separator

Plasma Heating and Current Drive by Neutral Beam and Alpha Particles

Energy Technology Data Exchange (ETDEWEB)

Kikuchi, M; Okumura, Y [Fusion Research and Development Directorate, Japan Atomic Energy Agency (Japan)

2012-09-15

The purpose of plasma heating is to raise the plasma temperature enough to produce a deuterium and tritium reaction (D + T {yields} {sup 4}He + n). The required plasma temperature T is in the range of 10-30 keV. Since the high temperature plasma is confined by a strong magnetic field, injection of energetic ions from outside to heat the plasma is difficult due to the Lorenz force. The most efficient way to heat the plasma by energetic particles is to inject high energy 'neutrals' which get ionized in the plasma. Neutral beam injection (NBI) with a beam energy much above the average kinetic energy of the plasma electrons or ions is used (beam energy typically {approx}40 keV - 1 MeV). This heating scheme is similar to warming up cold water by pouring in hot water. There are two types of neutral beam, called P-NBI and N-NBI (P- and N- means 'positive' and 'negative', respectively). P-NBI uses the acceleration of positively charged ions and their neutralization, while N-NBI uses the acceleration of negative ions (electrons attached to neutral atoms) and their neutralization. Details are given in NBI technology Section. The first demonstration of plasma heating by P-NBI was made in ORMAK and ATC in 1974, while that by N-NBI was made in JT-60U for the first time in 1996. ITER has also adopted the N-NBI system as the heating and current drive system with a beam energy of 1 MeV. Figure A typical bird's eye view of a tokamak with N-NBI and N-NBI (JT-60U) is shown. (author)

Laminar forced convective heat transfer to near-critical water in a tube

International Nuclear Information System (INIS)

Lee, Sang Ho

2003-01-01

Numerical modeling is carried out to investigate forced convective heat transfer to near-critical water in developing laminar flow through a circular tube. Due to large variations of thermo-physical properties such as density, specific heat, viscosity, and thermal conductivity near thermodynamic critical point, heat transfer characteristics show quite different behavior compared with pure forced convection. With flow acceleration along the tube unusual behavior of heat transfer coefficient and friction factor occurs when the fluid enthalpy passes through pseudocritical point of pressure in the tube. There is also a transition behavior from liquid-like phase to gas-like phase in the developing region. Numerical results with constant heat flux boundary conditions are obtained for reduced pressures from 1.09 to 1.99. Graphical results for velocity, temperature, and heat transfer coefficient with Stanton number are presented and analyzed

Investigation of micro-gravity effects on heat pipe thermal performance and working fluid behavior, phase B

Science.gov (United States)

Gier, K. D.; Smith, M. O.

1990-01-01

The purpose of this experiment is to develop an in-depth understanding of the behavior of heat pipes in space. Both fixed conductance heat pipes (FCHPs) with axial grooves and variable conductance heat pipes (VCHPs) with porous wicks will be investigated. This understanding will be applied to the development of improved performance heat pipes subjected to various accelerations in space, including those encountered on a lunar base or Mars mission. More efficient, reliable, and lighter weight spacecraft thermal control systems should result from these investigations.

Free surface deformation and heat transfer by thermocapillary convection

Science.gov (United States)

Fuhrmann, Eckart; Dreyer, Michael; Basting, Steffen; Bänsch, Eberhard

2016-04-01

Knowing the location of the free liquid/gas surface and the heat transfer from the wall towards the fluid is of paramount importance in the design and the optimization of cryogenic upper stage tanks for launchers with ballistic phases, where residual accelerations are smaller by up to four orders of magnitude compared to the gravity acceleration on earth. This changes the driving forces drastically: free surfaces become capillary dominated and natural or free convection is replaced by thermocapillary convection if a non-condensable gas is present. In this paper we report on a sounding rocket experiment that provided data of a liquid free surface with a nonisothermal boundary condition, i.e. a preheated test cell was filled with a cold but storable liquid in low gravity. The corresponding thermocapillary convection (driven by the temperature dependence of the surface tension) created a velocity field directed away from the hot wall towards the colder liquid and then in turn back at the bottom towards the wall. A deformation of the free surface resulting in an apparent contact angle rather different from the microscopic one could be observed. The thermocapillary flow convected the heat from the wall to the liquid and increased the heat transfer compared to pure conduction significantly. The paper presents results of the apparent contact angle as a function of the dimensionless numbers (Weber-Marangoni and Reynolds-Marangoni number) as well as heat transfer data in the form of a Nusselt number. Experimental results are complemented by corresponding numerical simulations with the commercial software Flow3D and the inhouse code Navier.

Experimental study on heat transfer augmentation for high heat flux removal in rib-roughened narrow channels

Energy Technology Data Exchange (ETDEWEB)

Islam, M.S.; Monde, Masanori [Saga Univ. (Japan); Hino, Ryutaro; Haga, Katsuhiro; Sudo, Yukio

1997-07-01

Frictional pressure drop and heat transfer performance in a very narrow rectangular channel having one-sided constant heat flux and repeated-ribs for turbulent flow have been investigated experimentally, and their experimental correlations were obtained using the least square method. The rib pitch-to-height ratios(p/k) were 10 and 20 while holding the rib height constant at 0.2mm, the Reynolds number(Re) from 2,414 to 98,458 under different channel heights of 1.2mm, 2.97mm, and 3.24mm, the rib height-to-channel equivalent diameter(k/De) of 0.03, 0.04, and 0.09 respectively. The results show that the rib-roughened surface augments heat transfer 2-3 times higher than that of the smooth surface with the expense of 2.8-4 times higher frictional pressure drop under Re=5000-10{sup 5}, p/k=10, and H=1.2mm. Experimental results obtained by channel height, H=1.2mm shows a little bit higher heat transfer and friction factor performance than the higher channel height, H=3.24mm. The effect of fin and consequently higher turbulence intensity are responsible for producing higher heat transfer rates. The obtained correlations could be used to design the cooling passages between the target plates to remove high heat flux up to 12MW/m{sup 2} generated at target plates in a high-intensity proton accelerator system. (author). 54 refs.

Experimental study on heat transfer augmentation for high heat flux removal in rib-roughened narrow channels

International Nuclear Information System (INIS)

Islam, M.S.; Monde, Masanori; Hino, Ryutaro; Haga, Katsuhiro; Sudo, Yukio.

1997-07-01

Frictional pressure drop and heat transfer performance in a very narrow rectangular channel having one-sided constant heat flux and repeated-ribs for turbulent flow have been investigated experimentally, and their experimental correlations were obtained using the least square method. The rib pitch-to-height ratios(p/k) were 10 and 20 while holding the rib height constant at 0.2mm, the Reynolds number(Re) from 2,414 to 98,458 under different channel heights of 1.2mm, 2.97mm, and 3.24mm, the rib height-to-channel equivalent diameter(k/De) of 0.03, 0.04, and 0.09 respectively. The results show that the rib-roughened surface augments heat transfer 2-3 times higher than that of the smooth surface with the expense of 2.8-4 times higher frictional pressure drop under Re=5000-10 5 , p/k=10, and H=1.2mm. Experimental results obtained by channel height, H=1.2mm shows a little bit higher heat transfer and friction factor performance than the higher channel height, H=3.24mm. The effect of fin and consequently higher turbulence intensity are responsible for producing higher heat transfer rates. The obtained correlations could be used to design the cooling passages between the target plates to remove high heat flux up to 12MW/m 2 generated at target plates in a high-intensity proton accelerator system. (author). 54 refs

Heat Load and Cooling Configurations of the PEFP DTL

International Nuclear Information System (INIS)

Kim, Han Sung; Kwon, Hyeok Jung; Cho, Yong Sub

2012-01-01

A 100 MeV proton linac is under development for Proton Engineering Frontier Project (PEFP). It consists of a 50 keV injector, 3 MeV RFQ and 100 MeV DTL. The accelerated proton beam can be extracted at 20 MeV and 100 MeV by using bending magnets. Therefore, the DTL for PEFP can be divided into two sections; one for 20 MeV DTL and the other is 100 MeV DTL. The 20 MeV DTL is composed of 4 tanks and driven by a single klystron. Duty factor of the 20 MeV section is 24%. To accelerate the beam from 20 MeV to 100 MeV, we use 7 tanks, which are driven by 7 independent RF sources. Duty factor of the 100 MeV section is reduced to 8%. From the viewpoint of the heat load, there are several differences between the 20 MeV section and 100 MeV section. First, as mentioned before, the duty factors are different. Second, the accelerating gradient is changed from 1.3 MV/m for 20 MeV section to 2.58 MV/m for 100 MeV section. Third, the types of the electroquadrupole magnets inside each drift tube are different. For the 20 MeV section, we used the pool type quadrupole magnets made of enamel wires due to the limited space. The hollow conductor type quadrupole magnets are used for 100 MeV section. The heat generations of each quadrupole magnet are 1.5 kW and 0.4 kW for 20 MeV section and 100 MeV section, respectively. Detailed heat load of DTL and the configuration of cooling loop are presented in this paper

Heat Load and Cooling Configurations of the PEFP DTL

Energy Technology Data Exchange (ETDEWEB)

Kim, Han Sung; Kwon, Hyeok Jung; Cho, Yong Sub [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-05-15

A 100 MeV proton linac is under development for Proton Engineering Frontier Project (PEFP). It consists of a 50 keV injector, 3 MeV RFQ and 100 MeV DTL. The accelerated proton beam can be extracted at 20 MeV and 100 MeV by using bending magnets. Therefore, the DTL for PEFP can be divided into two sections; one for 20 MeV DTL and the other is 100 MeV DTL. The 20 MeV DTL is composed of 4 tanks and driven by a single klystron. Duty factor of the 20 MeV section is 24%. To accelerate the beam from 20 MeV to 100 MeV, we use 7 tanks, which are driven by 7 independent RF sources. Duty factor of the 100 MeV section is reduced to 8%. From the viewpoint of the heat load, there are several differences between the 20 MeV section and 100 MeV section. First, as mentioned before, the duty factors are different. Second, the accelerating gradient is changed from 1.3 MV/m for 20 MeV section to 2.58 MV/m for 100 MeV section. Third, the types of the electroquadrupole magnets inside each drift tube are different. For the 20 MeV section, we used the pool type quadrupole magnets made of enamel wires due to the limited space. The hollow conductor type quadrupole magnets are used for 100 MeV section. The heat generations of each quadrupole magnet are 1.5 kW and 0.4 kW for 20 MeV section and 100 MeV section, respectively. Detailed heat load of DTL and the configuration of cooling loop are presented in this paper

The effect of centrifugal buoyancy on the heat transport in rotating Rayleigh-Bénard convection

Science.gov (United States)

Horn, Susanne; Aurnou, Jonathan

2017-11-01

In a rapidly rotating and differentially heated fluid, the centrifugal acceleration can play a similar role to that of gravity in generating convective motion. However, in the paradigm system of rotating Rayleigh-Bénard convection, centrifugal buoyancy is typically not considered in theoretical studies and, thus, usually undesired in laboratory experiments, despite being unavoidable. How centrifugal buoyancy affects the turbulent flow, including the heat transport, is still largely unknown, in particular, when it can be considered negligible. We study this problem by means of direct numerical simulations. Unlike in experiments, we are able to systematically vary the Froude number Fr (ratio of centrifugal to gravitational acceleration) and the Rossby number Ro (dimensionless rotation rate) independently, and even set each to zero exactly. We show that the centrifugal acceleration simultaneously leads to contending phenomena, e.g. reflected by an increase and a decrease of the center temperature, or a suppression and an enhancement of the heat transfer efficiency. Which one prevails as net effect strongly depends on the combination of Fr and Ro. Furthermore, we discuss implications for experiments of rapidly rotating convection. SH acknowledges funding by the Deutsche Forschungsgemeinschaft (DFG) under Grant HO 5890/1-1, JA by the NSF Geophysics Program.

Community petascale project for accelerator science and simulation: Advancing computational science for future accelerators and accelerator technologies

International Nuclear Information System (INIS)

Spentzouris, P.; Cary, J.; McInnes, L.C.; Mori, W.; Ng, C.; Ng, E.; Ryne, R.

2008-01-01

The design and performance optimization of particle accelerators are essential for the success of the DOE scientific program in the next decade. Particle accelerators are very complex systems whose accurate description involves a large number of degrees of freedom and requires the inclusion of many physics processes. Building on the success of the SciDAC-1 Accelerator Science and Technology project, the SciDAC-2 Community Petascale Project for Accelerator Science and Simulation (ComPASS) is developing a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and laser/plasma acceleration modelling. ComPASS is providing accelerator scientists the tools required to enable the necessary accelerator simulation paradigm shift from high-fidelity single physics process modeling (covered under SciDAC1) to high-fidelity multiphysics modeling. Our computational frameworks have been used to model the behavior of a large number of accelerators and accelerator R and D experiments, assisting both their design and performance optimization. As parallel computational applications, the ComPASS codes have been shown to make effective use of thousands of processors.

Design of a New Acceleration System for High-Current Pulsed Proton Beams from an ECR Source

Science.gov (United States)

Cooper, Andrew L.; Pogrebnyak, Ivan; Surbrook, Jason T.; Kelly, Keegan J.; Carlin, Bret P.; Champagne, Arthur E.; Clegg, Thomas B.

2014-03-01

A primary objective for accelerators at TUNL's Laboratory for Experimental Nuclear Astrophysics (LENA) is to maximize target beam intensity to ensure a high rate of nuclear events during each experiment. Average proton target currents of several mA are needed from LENA's electron cyclotron resonance (ECR) ion source because nuclear cross sections decrease substantially at energies of interest tube structures; and provide better heat dissipation by using deionized water to provide the current drain needed to establish the accelerating tube's voltage gradient. Details of beam optical modeling calculations, proposed accelerating tube design, and initial beam pulsing tests will be described. Work supported in part by USDOE Office of HE and Nuclear Physics.

ISOLDE - Accelerating Future

CERN Multimedia

CERN. Geneva

2003-01-01

Isotope Separation On-Line (ISOL) was first developed in Copenhagen in the late 50s. The technique was taken to CERN in the 60s and the CERN facility was given the name ISOLDE. The method is based on energetic protons hitting a solid target. The reaction products produced through spallation, fission and fragmentation are heated out in the form of an electrically neutral gas. In the subsequent steps the gas is ionized, accelerated and magnetically separated to produce isotopically pure beams for experiments in nuclear physics, atomic physics, astrophysics, solid state physics and for medical applications. An overview will be given of the physics at ISOLDE as well as over the techniques used to produce the necessary isotopes. Furthermore, a part of the talk will be dedicated to the future plans at ISOLDE including the proposal to build a next generation radioactive beam facility at CERN. The talk ends with a guided visit to the ISOLDE facility. Prerequisite knowledge: None.

Advanced concepts for acceleration

International Nuclear Information System (INIS)

Keefe, D.

1986-07-01

Selected examples of advanced accelerator concepts are reviewed. Such plasma accelerators as plasma beat wave accelerator, plasma wake field accelerator, and plasma grating accelerator are discussed particularly as examples of concepts for accelerating relativistic electrons or positrons. Also covered are the pulsed electron-beam, pulsed laser accelerator, inverse Cherenkov accelerator, inverse free-electron laser, switched radial-line accelerators, and two-beam accelerator. Advanced concepts for ion acceleration discussed include the electron ring accelerator, excitation of waves on intense electron beams, and two-wave combinations

Characterization of Single Phase and Two Phase Heat and Momentum Transport in a Spiraling Radial Inow Microchannel Heat Sink

Science.gov (United States)

Ruiz, Maritza

Thermal management of systems under high heat fluxes on the order of hundreds of W/cm2 is important for the safety, performance and lifetime of devices, with innovative cooling technologies leading to improved performance of electronics or concentrating solar photovoltaics. A novel, spiraling radial inflow microchannel heat sink for high flux cooling applications, using a single phase or vaporizing coolant, has demonstrated enhanced heat transfer capabilities. The design of the heat sink provides an inward swirl flow between parallel, coaxial disks that form a microchannel of 1 cm radius and 300 micron channel height with a single inlet and a single outlet. The channel is heated on one side through a conducting copper surface, and is essentially adiabatic on the opposite side to simulate a heat sink scenario for electronics or concentrated photovoltaics cooling. Experimental results on the heat transfer and pressure drop characteristics in the heat sink, using single phase water as a working fluid, revealed heat transfer enhancements due to flow acceleration and induced secondary flows when compared to unidirectional laminar fully developed flow between parallel plates. Additionally, thermal gradients on the surface are small relative to the bulk fluid temperature gain, a beneficial feature for high heat flux cooling applications. Heat flux levels of 113 W/cm2 at a surface temperature of 77 deg C were reached with a ratio of pumping power to heat rate of 0.03%. Analytical models on single phase flow are used to explore the parametric trends of the flow rate and passage geometry on the streamlines and pressure drop through the device. Flow boiling heat transfer and pressure drop characteristics were obtained for this heat sink using water at near atmospheric pressure as the working fluid for inlet subcooling levels ranging from 20 to 80 deg C and mean mass flux levels ranging from 184-716 kg/m. 2s. Flow enhancements similar to singlephase flow were expected, as well

Acceleration of tritons with a compact cyclotron

International Nuclear Information System (INIS)

Wegmann, H.; Huenges, E.; Muthig, H.; Moringa, H.

1981-01-01

With the compact cyclotron at the Faculty of Physics of the Technical University of Munich, tritons have been accelerated to an energy of 7 MeV. A safe and reliable operation of the gas supply for the ion source was obtained by a new tritium storage system. A quantity of 1500 Ci tritium is stored by two special Zr-Al getter pumps in a non-gaseous phase. The tritium can be released in well-defined amounts by heating the getter material. During triton acceleration the pressure in the cyclotron vacuum chamber is maintained only by a large titanium sputter-ion pump, thus forming a closed vacuum system without any exhaust of tritium contaminated gas. Any tritium contaminations in the air can be detected by an extremely sensitive tritium monitoring system. The triton beam with a maximum intensity of 30 μA has been used so far to produce neutron-rich radioisotopes such as 28 Mg, 43 K, or 72 Zn, which are successfully applied in tracer techniques in the studies of biological systems. (orig.)

Plasma heating by cluster injection: basic features and expected behaviour

International Nuclear Information System (INIS)

Bottiglioni, F.; Coutant, J.; Fois, M.; CEA Centre d'Etudes Nucleaires de Fontenay-aux-Roses, 92

1976-01-01

Each main component of an injection line (beam source, cluster ionizer, accelerating tube) is briefly discussed together with the behavior of clusters interacting with a plasma. Outlines of the experiment of cluster injection into TFR, in progress at Fontenay-aux-Roses are presented and discussed all along the paper. It is shown that high current densities at rather low energy per atom can be obtained by accelerated cluster beams. In present size toroidal devices, both ion temperature and density can be increased simultaneously without heating electrons. This feature could be attractive as long as tokamak losses are dominated by electrons. The extrapolation of the ionizers under construction does not seem to present much difficulty; on the contrary, the accelerating tube could be the most serious problem to solve. (40 references)

Effect of turbulence models on predicting convective heat transfer to hydrocarbon fuel at supercritical pressure

Directory of Open Access Journals (Sweden)

Tao Zhi

2016-10-01

Full Text Available A variety of turbulence models were used to perform numerical simulations of heat transfer for hydrocarbon fuel flowing upward and downward through uniformly heated vertical pipes at supercritical pressure. Inlet temperatures varied from 373 K to 663 K, with heat flux ranging from 300 kW/m2 to 550 kW/m2. Comparative analyses between predicted and experimental results were used to evaluate the ability of turbulence models to respond to variable thermophysical properties of hydrocarbon fuel at supercritical pressure. It was found that the prediction performance of turbulence models is mainly determined by the damping function, which enables them to respond differently to local flow conditions. Although prediction accuracy for experimental results varied from condition to condition, the shear stress transport (SST and launder and sharma models performed better than all other models used in the study. For very small buoyancy-influenced runs, the thermal-induced acceleration due to variations in density lead to the impairment of heat transfer occurring in the vicinity of pseudo-critical points, and heat transfer was enhanced at higher temperatures through the combined action of four thermophysical properties: density, viscosity, thermal conductivity and specific heat. For very large buoyancy-influenced runs, the thermal-induced acceleration effect was over predicted by the LS and AB models.

Effects of laser-polarization and wiggler magnetic fields on electron acceleration in laser-cluster interaction

Science.gov (United States)

Singh Ghotra, Harjit; Kant, Niti

2018-06-01

We examine the electron dynamics during laser-cluster interaction. In addition to the electrostatic field of an individual cluster and laser field, we consider an external transverse wiggler magnetic field, which plays a pivotal role in enhancing the electron acceleration. Single-particle simulation has been presented with a short pulse linearly polarized as well as circularly polarized laser pulses for electron acceleration in a cluster. The persisting Coulomb field allows the electron to absorb energy from the laser field. The stochastically heated electron finds a weak electric field at the edge of the cluster from where it is ejected. The wiggler magnetic field connects the regions of the stochastically heated, ejected electron from the cluster and high energy gain by the electron from the laser field outside the cluster. This increases the field strength and hence supports the electron to meet the phase of the laser field for enhanced acceleration. A long duration resonance appears with an optimized magnetic wiggler field of about 3.4 kG. Hence, the relativistic energy gain by the electron is enhanced up to a few 100 MeV with an intense short pulse laser with an intensity of about 1019 W cm‑2 in the presence of a wiggler magnetic field.

Optimizing pulse shaping and zooming for acceleration to high velocities and fusion neutron production on the Nike laser

Science.gov (United States)

Karasik, Max; Weaver, J. L.; Aglitskiy, Y.; Zalesak, S. T.; Velikovich, A. L.; Oh, J.; Obenschain, S. P.; Arikawa, Y.; Watari, T.

2010-11-01

We will present results from follow-on experiments to the record-high velocities of 1000 km/s achieved on Nike [Karasik et al., Phys. Plasmas 17, 056317 (2010) ], in which highly accelerated planar foils of deuterated polystyrene were made to collide with a witness foil to produce extreme shock pressures and result in heating of matter to thermonuclear temperatures. Still higher velocities and higher target densities are required for impact fast ignition. The aim of these experiments is shaping the driving pulse to minimize shock heating of the accelerated target and using the focal zoom capability of Nike to achieve higher densities and velocities. Spectroscopic measurements of electron temperature achieved upon impact will complement the neutron time-of-flight ion temperature measurement. Work is supported by US DOE and Office of Naval Research.

Accelerating tube for the ''EG-1'' electrostatic accelerator

International Nuclear Information System (INIS)

Romanov, V.A.; Ivanov, V.V.; Krupnov, E.P.; Debin, V.K.; Dudkin, N.I.; Volodin, V.I.

1980-01-01

A design of an accelerating tube (AT) for an electrostatic accelerator of the EG-1 type is described. Primary consideration in the development of the AT has been given to increasing the electric strength of accelerating gaps, the vacuum conductivity and better insulator screening from charged particles. After AT vacuum and high-voltage ageing in the accelerator, a hydrogen ions beam of up to 80 μA has been produced. The beam was adequately shaped in the energy range from 1.8 to 5.0 MeV [ru

Solutions to mitigate heat loads due to electrons on sensitive components of ITER HNB beamlines

Energy Technology Data Exchange (ETDEWEB)

Sartori, Emanuele, E-mail: emanuele.sartori@gmail.com [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova (Italy); Veltri, Pierluigi; Dalla Palma, Mauro; Agostinetti, Piero [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova (Italy); Hemsworth, Ronald; Singh, Mahendrajit [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Serianni, Gianluigi [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova (Italy)

2016-11-01

Highlights: • Energetic electrons leaking out of the ITER HNB accelerator are simulated. • Electrons generated along the ITER HNB beamline are simulated. • Heat loads and heat load maps on cryopumps are calculated for ITER HNB and test facility. • Protection solutions that will be installed are presented and their effect discussed. - Abstract: The operation of neutral beam injectors for plasma heating and current drive in a fusion device provides challenges in the thermal management of beamline components. Sensitive components such as the cryogenic pumps at beamline periphery shall be protected from the heat flux due to stray electrons. These are emitted by the negative ion accelerator or generated along the beamline by interaction of fast electrons, ions or atoms with background gas and surfaces. In this article the case of the ITER Heating Neutral Beam (HNB) and its test facility MITICA is discussed, for which the beam parameters and the required pulse length of one hour is a major leap forward with respect to the present experience with neutral beam systems. The engineering solutions adopted for effective cryopump protection against the heat load from electrons are described. The use of three-dimensional numerical simulations of particle trajectories in the complex geometry of the beamline was needed for the quantitative estimations of the heat loads. The presented solutions were optimized to minimize the impact on gas pumping and on the functionality of other components.

CAS CERN Accelerator School superconductivity in particle accelerators

International Nuclear Information System (INIS)

Turner, S.

1989-01-01

One of the objectives of the CERN Accelerator School is to run courses on specialised topics in the particle accelerator field. The present volume contains the proceedings of one such course, this time organized in conjunction with the Deutsches Elektronen Synchrotron (DESY) on the subject of superconductivity in particle accelerators. This course reflects the very considerable progress made over the last few years in the use of the technology for the magnet and radio-frequency systems of many large and small accelerators already in use or nearing completion, while also taking account of the development work now going on for future machines. The lectures cover the theory of superconductivity, cryogenics and accelerator magnets and cavities, while the seminars include superfluidity, superconductors, special magnets and the prospects for high-temperature superconductors. (orig.)

Design and Proof-of-Concept Use of a Circular PMMA Platform with 16-Well Sample Capacity for Microwave-Accelerated Bioassays.

Science.gov (United States)

Mohammed, Muzaffer; Aslan, Kadir

2013-01-01

We demonstrate the design and the proof-of-concept use of a new, circular poly(methyl methacrylate)-based bioassay platform (PMMA platform), which affords for the rapid processing of 16 samples at once. The circular PMMA platform (5 cm in diameter) was coated with a silver nanoparticle film to accelerate the bioassay steps by microwave heating. A model colorimetric bioassay for biotinylated albumin (using streptavidin-labeled horse radish peroxidase) was performed on the PMMA platform coated with and without silver nanoparticles (a control experiment), and at room temperature and using microwave heating. It was shown that the simulated temperature profile of the PMMA platform during microwave heating were comparable to the real-time temperature profile during actual microwave heating of the constructed PMMA platform in a commercial microwave oven. The model colorimetric bioassay for biotinylated albumin was successfully completed in ~2 min (total assay time) using microwave heating, as compared to 90 min at room temperature (total assay time), which indicates a ~45-fold decrease in assay time. Our PMMA platform design afforded for significant reduction in non-specific interactions and low background signal as compared to non-silvered PMMA surfaces when employed in a microwave-accelerated bioassay carried out in a conventional microwave cavity.

Study on the limiting acceleration rate in the VLEPP linear accelerator

International Nuclear Information System (INIS)

Balakin, V.E.; Brezhnev, O.N.; Zakhvatkin, M.N.

1987-01-01

To realize the design of colliding linear electron-positron beams it is necessary to solve the radical problem of production of accelerating structure with acceleration rate of approximately 100 MeV/m which can accelerate 10 12 particles in a bunch. Results of experimental studies of the limiting acceleration rate in the VLEPP accelerating structure are presented. Accelerating sections of different length were tested. When testing sections 29 cm long the acceleration rate of 55 MeV/m was attained, and for 1 m section the value reached 40 MeV/m. The maximum rate of acceleration (90 MeV/m) was attained when electric field intensity on the structure surface constituted more than 150 MV/m

Particle-accelerator decommissioning

International Nuclear Information System (INIS)

Opelka, J.H.; Mundis, R.L.; Marmer, G.J.; Peterson, J.M.; Siskind, B.; Kikta, M.J.

1979-12-01

Generic considerations involved in decommissioning particle accelerators are examined. There are presently several hundred accelerators operating in the United States that can produce material containing nonnegligible residual radioactivity. Residual radioactivity after final shutdown is generally short-lived induced activity and is localized in hot spots around the beam line. The decommissioning options addressed are mothballing, entombment, dismantlement with interim storage, and dismantlement with disposal. The recycle of components or entire accelerators following dismantlement is a definite possibility and has occurred in the past. Accelerator components can be recycled either immediately at accelerator shutdown or following a period of storage, depending on the nature of induced activation. Considerations of cost, radioactive waste, and radiological health are presented for four prototypic accelerators. Prototypes considered range from small accelerators having minimal amounts of radioactive mmaterial to a very large accelerator having massive components containing nonnegligible amounts of induced activation. Archival information on past decommissionings is presented, and recommendations concerning regulations and accelerator design that will aid in the decommissioning of an accelerator are given

Method and apparatus for accelerating a solid mass

International Nuclear Information System (INIS)

Tidman, D.A.; Goldstein, Y.A.

1984-01-01

An axi-symmetrical projectile, having a mass ranging from fractions of a gram to kilograms, is accelerated to velocities in the range of 10 5 to 10 7 centimeters per second by a propelling force produced by a plasma resulting from electric discharge. The discharge is imploded against the projectile surface so lines of the magnetic fields are approximately azimuthal around the projectile axis. The projectile is tapered so it experiences a net, stable axial accelerating force along the accelerator axis by the combined action of the magnetic field producing radially directed momentum and pressure on the plasma, the interaction of the magnetic field and ions induced by the plasma on the surface, as well as material the plasma ablates from the surface. The plasma discharge is initiated either in low density background gas between anode and cathode of a discharge module, or along an insulator surface between the electrodes in low density background gas. Alternatively, in either of these situations the discharge can be initiated in a gas which is produced by ablation of the projectile surface. In an alternative situation, the projectile acts as a switch for triggering discharges. Eddy current heating of the projectile is minimized by shaping the discharge current pulse so the plasma has a relatively weak magnetic field when it arrives at the surface, or by making the projectile electrically non-conducting. To provide a long acceleration path, a series of modules is aligned. In one embodiment, the projectile position, as it advances between modules, is sensed and discharges are switched on sequentially in the modules

Accelerated weathering of composite cements used for immobilisation

International Nuclear Information System (INIS)

Borges, P. H. R.; Milestone, N. B.; Streatfield, R. E.

2008-01-01

Trying to estimate the long-term durability of cemented waste-forms is a difficult task as the cement matrix is a reactive medium and interactions can occur with the encapsulated waste as well as with the environment. There are few studies of samples that have been stored under controlled conditions for more than 10-15 years. waste-forms are now being expected to last hundreds of years, much of that likely to be in some form of storage where sample integrity is important. There is also the concern that results from any long-term samples may only be indicative as both formulations and materials change with time. This paper discusses changes in physical properties that occur in composite cements when some of the short-term accelerated procedures employed in construction testing are applied to encapsulating matrices. Changes after increased temperature of curing, wetting/drying and accelerated carbonation are discussed. Many of the encapsulating formulations currently used are composite cements where large replacement levels of OPC with supplementary cementing materials (SCMs) such as PFA or BFS are made, primarily to reduce heat output. Accelerating the exposure conditions, either by increasing temperature or through wetting/drying has the effect of changing the hydration pattern of the composite cement by generating more hydration in the SCMs than would normally occur. The large amount of porosity that occurs because of limited hydration allows intrusion of gases and ready movement of water, so the samples subjected to accelerated testing do not appear as durable as expected if stored at ambient. (authors)

Source-to-accelerator quadrupole matching section for a compact linear accelerator

Science.gov (United States)

Seidl, P. A.; Persaud, A.; Ghiorso, W.; Ji, Q.; Waldron, W. L.; Lal, A.; Vinayakumar, K. B.; Schenkel, T.

2018-05-01

Recently, we presented a new approach for a compact radio-frequency (RF) accelerator structure and demonstrated the functionality of the individual components: acceleration units and focusing elements. In this paper, we combine these units to form a working accelerator structure: a matching section between the ion source extraction grids and the RF-acceleration unit and electrostatic focusing quadrupoles between successive acceleration units. The matching section consists of six electrostatic quadrupoles (ESQs) fabricated using 3D-printing techniques. The matching section enables us to capture more beam current and to match the beam envelope to conditions for stable transport in an acceleration lattice. We present data from an integrated accelerator consisting of the source, matching section, and an ESQ doublet sandwiched between two RF-acceleration units.

Electrostatic accelerators

CERN Document Server

Hinterberger, F

2006-01-01

The principle of electrostatic accelerators is presented. We consider Cockcroft– Walton, Van de Graaff and Tandem Van de Graaff accelerators. We resume high voltage generators such as cascade generators, Van de Graaff band generators, Pelletron generators, Laddertron generators and Dynamitron generators. The speci c features of accelerating tubes, ion optics and methods of voltage stabilization are described. We discuss the characteristic beam properties and the variety of possible beams. We sketch possible applications and the progress in the development of electrostatic accelerators.

Acceleration of 14C beams in electrostatic accelerators

International Nuclear Information System (INIS)

Rowton, L.J.; Tesmer, J.R.

1981-01-01

Operational problems in the production and acceleration of 14 C beams for nuclear structure research in Los Alamos National Laboratory's Van de Graaff accelerators are discussed. Methods for the control of contamination in ion sources, accelerators and personnel are described. Sputter source target fabrication techniques and the relative beam production efficiencies of various types of bound particulate carbon sputter source targets are presented

Multiperiodic accelerator structures for linear particle accelerators

International Nuclear Information System (INIS)

Tran, D.T.

1975-01-01

High efficiency linear accelerator structures, comprised of a succession of cylindrical resonant cavities for acceleration, are described. Coupling annular cavities are located at the periphery, each being coupled to two adjacent cylindrical cavities. (auth)

Advanced approaches to high intensity laser-driven ion acceleration

International Nuclear Information System (INIS)

Henig, Andreas

2010-01-01

Since the pioneering work that was carried out 10 years ago, the generation of highly energetic ion beams from laser-plasma interactions has been investigated in much detail in the regime of target normal sheath acceleration (TNSA). Creation of ion beams with small longitudinal and transverse emittance and energies extending up to tens of MeV fueled visions of compact, laser-driven ion sources for applications such as ion beam therapy of tumors or fast ignition inertial con finement fusion. However, new pathways are of crucial importance to push the current limits of laser-generated ion beams further towards parameters necessary for those applications. The presented PhD work was intended to develop and explore advanced approaches to high intensity laser-driven ion acceleration that reach beyond TNSA. In this spirit, ion acceleration from two novel target systems was investigated, namely mass-limited microspheres and nm-thin, free-standing diamond-like carbon (DLC) foils. Using such ultrathin foils, a new regime of ion acceleration was found where the laser transfers energy to all electrons located within the focal volume. While for TNSA the accelerating electric field is stationary and ion acceleration is spatially separated from laser absorption into electrons, now a localized longitudinal field enhancement is present that co-propagates with the ions as the accompanying laser pulse pushes the electrons forward. Unprecedented maximum ion energies were obtained, reaching beyond 0.5 GeV for carbon C 6+ and thus exceeding previous TNSA results by about one order of magnitude. When changing the laser polarization to circular, electron heating and expansion were shown to be efficiently suppressed, resulting for the first time in a phase-stable acceleration that is dominated by the laser radiation pressure which led to the observation of a peaked C 6+ spectrum. Compared to quasi-monoenergetic ion beam generation within the TNSA regime, a more than 40 times increase in

Advanced approaches to high intensity laser-driven ion acceleration

Energy Technology Data Exchange (ETDEWEB)

Henig, Andreas

2010-04-26

Since the pioneering work that was carried out 10 years ago, the generation of highly energetic ion beams from laser-plasma interactions has been investigated in much detail in the regime of target normal sheath acceleration (TNSA). Creation of ion beams with small longitudinal and transverse emittance and energies extending up to tens of MeV fueled visions of compact, laser-driven ion sources for applications such as ion beam therapy of tumors or fast ignition inertial con finement fusion. However, new pathways are of crucial importance to push the current limits of laser-generated ion beams further towards parameters necessary for those applications. The presented PhD work was intended to develop and explore advanced approaches to high intensity laser-driven ion acceleration that reach beyond TNSA. In this spirit, ion acceleration from two novel target systems was investigated, namely mass-limited microspheres and nm-thin, free-standing diamond-like carbon (DLC) foils. Using such ultrathin foils, a new regime of ion acceleration was found where the laser transfers energy to all electrons located within the focal volume. While for TNSA the accelerating electric field is stationary and ion acceleration is spatially separated from laser absorption into electrons, now a localized longitudinal field enhancement is present that co-propagates with the ions as the accompanying laser pulse pushes the electrons forward. Unprecedented maximum ion energies were obtained, reaching beyond 0.5 GeV for carbon C{sup 6+} and thus exceeding previous TNSA results by about one order of magnitude. When changing the laser polarization to circular, electron heating and expansion were shown to be efficiently suppressed, resulting for the first time in a phase-stable acceleration that is dominated by the laser radiation pressure which led to the observation of a peaked C{sup 6+} spectrum. Compared to quasi-monoenergetic ion beam generation within the TNSA regime, a more than 40 times

Accelerator Based Neutron Beams for Neutron Capture Therapy

International Nuclear Information System (INIS)

Yanch, Jacquelyn C.

2003-01-01

The DOE-funded accelerator BNCT program at the Massachusetts Institute of Technology has resulted in the only operating accelerator-based epithermal neutron beam facility capable of generating significant dose rates in the world. With five separate beamlines and two different epithermal neutron beam assemblies installed, we are currently capable of treating patients with rheumatoid arthritis in less than 15 minutes (knee joints) or 4 minutes (finger joints) or irradiating patients with shallow brain tumors to a healthy tissue dose of 12.6 Gy in 3.6 hours. The accelerator, designed by Newton scientific Incorporated, is located in dedicated laboratory space that MIT renovated specifically for this project. The Laboratory for Accelerator Beam Applications consists of an accelerator room, a control room, a shielded radiation vault, and additional laboratory space nearby. In addition to the design, construction and characterization of the tandem electrostatic accelerator, this program also resulted in other significant accomplishments. Assemblies for generating epithermal neutron beams were designed, constructed and experimentally evaluated using mixed-field dosimetry techniques. Strategies for target construction and target cooling were implemented and tested. We demonstrated that the method of submerged jet impingement using water as the coolant is capable of handling power densities of up to 6 x 10(sup 7) W/m(sup 2) with heat transfer coefficients of 10(sup 6)W/m(sup 2)-K. Experiments with the liquid metal gallium demonstrated its superiority compared with water with little effect on the neutronic properties of the epithermal beam. Monoenergetic proton beams generated using the accelerator were used to evaluate proton RBE as a function of LET and demonstrated a maximum RBE at approximately 30-40 keV/um, a finding consistent with results published by other researchers. We also developed an experimental approach to biological intercomparison of epithermal beams and

Safety confirmation study of TRUEX solvent by accelerating rate calorimeter (ARC)

International Nuclear Information System (INIS)

Sato, Yoshihiko; Hirumachi, Suguru; Takeda, Shinso; Kanazawa, Yoshito; Sasaya, Shinji

1999-02-01

In order to confirm the engineering safety on the TRUEX solvent (mixed solvent of CMPO/TBP/n-dodecane) for separating the transuranics from high-level activity liquid waste in advanced nuclear fuel recycling technological R and D, thermal behavior and pressure behavior in heating PUREX solvent (mixed solvent of 30% TBP-n-dodecane), TRUEX solvent and in the exothermic reaction of TRUEX solvent etc. and nitric acid in sealed adiabatic system which was severer condition than actual plant were measured by using accelerating rate calorimeter (ARC). The Arrhenius parameters (activation energy and frequency factor) which are necessary for the evaluation of reaction rate was examined from the measurement data in ARC. Analytical method and analysis condition of reaction products were examined in order to clarify chemical form of reaction products in exothermic reaction between solvent and nitric acid in ARC, and the qualitative evaluation was carried out. Main results are shown in the following. 1) TBP, CMPO, n-dodecane and 10 M nitric acid hardly exothermed in the simple substance. 2) On the solvent phase after the solvent contacted with 10 M nitric acid and the equilibrium has been attained (single-phase sample), the heat quantity per unit sample weight of the TRUEX solvent tended to be bigger than that of the PUREX solvent when heat quantity was evaluated in ARC. However, on the mixed sample of solvent and 10 M nitric acid enclosed in a sample container simultaneously (two phase system sample), the heat quantity per unit solvent weight was almost equivalent for PUREX solvent and TRUEX solvent. 3) The kinetic analysis was carried out, and on the TBP-10 M nitric acid single-phase sample, the activation energy of the reaction was evaluated to be 118 kJ/mol. Its activation energy was approximately equal to 112 kJ/mol by Nichols. The reaction rate constant was calculated, and it was shown that reaction rate constants of PUREX solvent-10 M nitric acid single-phase sample and

Beam transport through electrostatic accelerators and matching into post accelerators

International Nuclear Information System (INIS)

Larson, J.D.

1986-01-01

Ion beam transport through electrostatic acceleration is briefly reviewed. Topics discussed include injection, matching into the low-energy acceleration stage, matching from the terminal stripper into the high-energy stage, transport to a post accelerator, space charge, bunching isochronism, dispersion and charge selection. Beam transport plans for the proposed Vivitron accelerator are described. (orig.)

Interim Policy Options for Commercialization of Solar Heating and Cooling Systems.

Science.gov (United States)

Bezdek, Roger

This interim report reviews the major incentive policy options available to accelerate market penetration of solar heating and cooling (SHAC) systems. Feasible policy options designed to overcome existing barriers to commercial acceptance and market penetration are identified and evaluated. The report is divided into seven sections, each dealing…

Modeling of secondary emission processes in the negative ion based electrostatic accelerator of the International Thermonuclear Experimental Reactor

Directory of Open Access Journals (Sweden)

G. Fubiani

2008-01-01

Full Text Available The negative ion electrostatic accelerator for the neutral beam injector of the International Thermonuclear Experimental Reactor (ITER is designed to deliver a negative deuterium current of 40 A at 1 MeV. Inside the accelerator there are several types of interactions that may create secondary particles. The dominating process originates from the single and double stripping of the accelerated negative ion by collision with the residual molecular deuterium gas (≃29% losses. The resulting secondary particles (positive ions, neutrals, and electrons are accelerated and deflected by the electric and magnetic fields inside the accelerator and may induce more secondaries after a likely impact with the accelerator grids. This chain of reactions is responsible for a non-negligible heat load on the grids and must be understood in detail. In this paper, we will provide a comprehensive summary of the physics involved in the process of secondary emission in a typical ITER-like negative ion electrostatic accelerator together with a precise description of the numerical method and approximations involved. As an example, the multiaperture-multigrid accelerator concept will be discussed.

Can Accelerators Accelerate Learning?

International Nuclear Information System (INIS)

Santos, A. C. F.; Fonseca, P.; Coelho, L. F. S.

2009-01-01

The 'Young Talented' education program developed by the Brazilian State Funding Agency (FAPERJ)[1] makes it possible for high-schools students from public high schools to perform activities in scientific laboratories. In the Atomic and Molecular Physics Laboratory at Federal University of Rio de Janeiro (UFRJ), the students are confronted with modern research tools like the 1.7 MV ion accelerator. Being a user-friendly machine, the accelerator is easily manageable by the students, who can perform simple hands-on activities, stimulating interest in physics, and getting the students close to modern laboratory techniques.

Can Accelerators Accelerate Learning?

Science.gov (United States)

Santos, A. C. F.; Fonseca, P.; Coelho, L. F. S.

2009-03-01

The 'Young Talented' education program developed by the Brazilian State Funding Agency (FAPERJ) [1] makes it possible for high-schools students from public high schools to perform activities in scientific laboratories. In the Atomic and Molecular Physics Laboratory at Federal University of Rio de Janeiro (UFRJ), the students are confronted with modern research tools like the 1.7 MV ion accelerator. Being a user-friendly machine, the accelerator is easily manageable by the students, who can perform simple hands-on activities, stimulating interest in physics, and getting the students close to modern laboratory techniques.

Accelerating the energy policy turnaround with combined heat and power units; Mit Blockheizkraftwerken die Energiewende rund machen

Energy Technology Data Exchange (ETDEWEB)

Lange, Joerg; Geiler, Nikolaus [Klimabuendnis Freiburg, Freiburg im Breisgau (Germany)

2013-03-15

No other type of decentralized power plants transforms natural gas to electric power so efficiently as a combined heat and power unit. In the long term, the climate-friendly effect using renewable hydrogen or renewably generated 'natural gas' even could be increased. Thus, combined heat and power units are ideal to achieve the national climate change objectives. Despite their advantages, the implementation of combined heat and power units advances only sluggishly.

Plutonium (TRU) transmutation and {sup 233}U production by single-fluid type accelerator molten-salt breeder (AMSB)

Energy Technology Data Exchange (ETDEWEB)

Furukaw, Kazuo [Tokai Univ., Kanagawa (Japan); Kato, Yoshio [Japan Atom. Ene. Res. Inst., Ibaraki (Japan); Chigrinov, Sergey E. [Academy of Science, Minsk (Belarus)

1995-10-01

For practical/industrial disposition of Pu(TRU) by accelerator facility, not only physical soundness and safety but also the following technological rationality should be required: (1) few R&D items including radiation damage, heat removal and material compatibility; (2) few operation/maintenance/processing works: (3) few reproduction of radioactivity; (4) effective energy production in parallel. This will be achieved by the new modification of Th-fertilizing Single-Fluid type Accelerator Molten-Salt Breeder (AMSB), by which a global nuclear energy strategy for next century might be prepared.

Prospective utilization of accelerated heavy ions in basic and applied research

International Nuclear Information System (INIS)

Flerov, G.; Oganesyan, Yu.

1982-01-01

Some important and interesting trends of heavy ion physics are briefly presented, such as giant processes which are characterized by fundamental restructuring of nuclear systems containing hundreds of nucleons, the mechanism of heavy nuclei interaction, the study of nuclear matter compression, the study of the specificity of heating and thermal conductivity of nuclear matter, the study of heavy ion/nucleus interactions at energies of 200 to 300 MeV/nucleon when the meson degree of freedom becomes manifest, the possibility of the production of ions with a large excess or deficiency of neutrons, new possibilities for determining the fission barrier, the critical verification of fundamental physical concepts of quantum electrodynamics and other possibilities of using accelerated heavy ions. The significance of heavy ion physics for the development of acceleration technologies is also described. (B.S.)

Development of High Heat Input Welding Offshore Steel as Normalized Condition

Science.gov (United States)

Deng, Wei; Qin, Xiaomei

The heavy plate used for offshore structure is one of the important strategic products. In recent years, there is an increasing demand for heavy shipbuilding steel plate with excellent weldability in high heat input welding. During the thermal cycle, the microstructure of the heat affected zone (HAZ) of plates was damaged, and this markedly reduced toughness of HAZ. So, how to improve the toughness of HAZ has been a key subject in the fields of steel research. Oxide metallurgy is considered as an effective way to improve toughness of HAZ, because it could be used to retard grain growth by fine particles, which are stable at the high temperature.The high strength steel plate, which satisfies the low temperature specification, has been applied to offshore structure. Excellent properties of the plates and welded joints were obtained by oxide metallurgy technology, latest controlled rolling and accelerated cooling technology using Ultra-Fast Cooling (an on-line accelerated cooling system). The 355MPa-grade high strength steel plates with normalizing condition were obtained, and the steels have excellent weldability with heat input energy of 79 287kJ/cm, and the nil ductility transition (NDT) temperature was -70°C, which can satisfy the construction of offshore structure in cold regions.

Accelerations in Flight

Science.gov (United States)

Doolittle, J H

1925-01-01

This work on accelerometry was done at McCook Field for the purpose of continuing the work done by other investigators and obtaining the accelerations which occur when a high-speed pursuit airplane is subjected to the more common maneuvers. The accelerations obtained in suddenly pulling out of a dive with well-balanced elevators are shown to be within 3 or 4 per cent of the theoretically possible accelerations. The maximum acceleration which a pilot can withstand depends upon the length of time the acceleration is continued. It is shown that he experiences no difficulty under the instantaneous accelerations as high as 7.8 G., but when under accelerations in excess of 4.5 G., continued for several seconds, he quickly loses his faculties.

Theoretical Investigations of Plasma-Based Accelerators and Other Advanced Accelerator Concepts

International Nuclear Information System (INIS)

Shuets, G.

2004-01-01

Theoretical investigations of plasma-based accelerators and other advanced accelerator concepts. The focus of the work was on the development of plasma based and structure based accelerating concepts, including laser-plasma, plasma channel, and microwave driven plasma accelerators

Ion acceleration from relativistic laser nano-target interaction

International Nuclear Information System (INIS)

Jung, Daniel

2012-01-01

Laser-ion acceleration has been of particular interest over the last decade for fundamental as well as applied sciences. Remarkable progress has been made in realizing laser-driven accelerators that are cheap and very compact compared with conventional rf-accelerators. Proton and ion beams have been produced with particle energies of up to 50 MeV and several MeV/u, respectively, with outstanding properties in terms of transverse emittance and current. These beams typically exhibit an exponentially decaying energy distribution, but almost all advanced applications, such as oncology, proton imaging or fast ignition, require quasimonoenergetic beams with a low energy spread. The majority of the experiments investigated ion acceleration in the target normal sheath acceleration (TNSA) regime with comparably thick targets in the μm range. In this thesis ion acceleration is investigated from nm-scaled targets, which are partially produced at the University of Munich with thickness as low as 3 nm. Experiments have been carried out at LANL's Trident high-power and high-contrast laser (80 J, 500 fs, λ=1054 nm), where ion acceleration with these nano-targets occurs during the relativistic transparency of the target, in the so-called Breakout afterburner (BOA) regime. With a novel high resolution and high dispersion Thomson parabola and ion wide angle spectrometer, thickness dependencies of the ions angular distribution, particle number, average and maximum energy have been measured. Carbon C 6+ energies reached 650 MeV and 1 GeV for unheated and heated targets, respectively, and proton energies peaked at 75 MeV and 120 MeV for diamond and CH 2 targets. Experimental data is presented, where the conversion efficiency into carbon C 6+ (protons) is investigated and found to have an up to 10fold (5fold) increase over the TNSA regime. With circularly polarized laser light, quasi-monoenergetic carbon ions have been generated from the same nm-scaled foil targets at Trident with an

A shielding design for an accelerator-based neutron source for boron neutron capture therapy

Energy Technology Data Exchange (ETDEWEB)

Hawk, A.E.; Blue, T.E. E-mail: blue.1@osu.edu; Woollard, J.E

2004-11-01

Research in boron neutron capture therapy (BNCT) at The Ohio State University Nuclear Engineering Department has been primarily focused on delivering a high quality neutron field for use in BNCT using an accelerator-based neutron source (ABNS). An ABNS for BNCT is composed of a proton accelerator, a high-energy beam transport system, a {sup 7}Li target, a target heat removal system (HRS), a moderator assembly, and a treatment room. The intent of this paper is to demonstrate the advantages of a shielded moderator assembly design, in terms of material requirements necessary to adequately protect radiation personnel located outside a treatment room for BNCT, over an unshielded moderator assembly design.

Large tandem accelerators

International Nuclear Information System (INIS)

Jones, C.M.

1976-01-01

The increasing importance of energetic heavy ion beams in the study of atomic physics, nuclear physics, and materials science has partially or wholly motivated the construction of a new generation of tandem accelerators designed to operate at maximum terminal potentials in the range 14 to 30 MV. In addition, a number of older tandem accelerators are now being significantly upgraded to improve their heavy ion performance. Both of these developments have reemphasized the importance of negative heavy ion sources. The new large tandem accelerators are described, and the requirements placed on negative heavy ion source technology by these and other tandem accelerators used for the acceleration of heavy ions are discussed. First, a brief description is given of the large tandem accelerators which have been completed recently, are under construction, or are funded for construction, second, the motivation for construction of these accelerators is discussed, and last, criteria for negative ion sources for use with these accelerators are presented

Acceleration of O+ from the cusp to the plasma sheet

Science.gov (United States)

Liao, J.; Kistler, L. M.; Mouikis, C. G.; Klecker, B.; Dandouras, I.

2015-02-01

Heavy ions from the ionosphere that are accelerated in the cusp/cleft have been identified as a direct source for the hot plasma in the plasma sheet. However, the details of the acceleration and transport that transforms the originally cold ions into the hot plasma sheet population are not fully understood. The polar orbit of the Cluster satellites covers the main transport path of the O+ from the cusp to the plasma sheet, so Cluster is ideal for tracking its velocity changes. However, because the cusp outflow is dispersed according to its velocity as it is transported to the tail, due to the velocity filter effect, the observed changes in beam velocity over the Cluster orbit may simply be the result of the spacecraft accessing different spatial regions and not necessarily evidence of acceleration. Using the Cluster Ion Spectrometry/Composition Distribution Function instrument onboard Cluster, we compare the distribution function of streaming O+ in the tail lobes with the initial distribution function observed over the cusp and reveal that the observations of energetic streaming O+ in the lobes around -20 RE are predominantly due to the velocity filter effect during nonstorm times. During storm times, the cusp distribution is further accelerated. In the plasma sheet boundary layer, however, the average O+ distribution function is above the upper range of the outflow distributions at the same velocity during both storm and nonstorm times, indicating that acceleration has taken place. Some of the velocity increase is in the direction perpendicular to the magnetic field, indicating that the E × B velocity is enhanced. However, there is also an increase in the parallel direction, which could be due to nonadiabatic acceleration at the boundary or wave heating.

Repetitive nanosecond electron accelerators type URT-1 for radiation technology

Science.gov (United States)

Sokovnin, S. Yu.; Balezin, M. E.

2018-03-01

The electron accelerator URT-1М-300 for mobile installation was created for radiation disinfecting to correct drawbacks that were found the URT-1M electron accelerator operation (the accelerating voltage up to 1 МV, repetition rate up to 300 pps, electron beam size 400 × 100 mm, the pulse width about 100 ns). Accelerator configuration was changed that allowed to reduce significantly by 20% tank volume with oil where is placed the system of formation high-voltage pulses, thus the average power of the accelerator is increased by 6 times at the expense of increase in pulses repetition rate. Was created the system of the computerized monitoring parameters (output parameters and thermal mode) and remote control of the accelerator (charge voltage, pulse repetition rate), its elements and auxiliary systems (heat of the thyratron, vacuum system), the remote control panel is connected to the installation by the fiber-optical channel, what lightens the work for service personnel. For generating an electron beam up to 400 mm wide there are used metal- ceramic] and metal-dielectric cold cathodes of several emission elements (plates) with a non-uniform distribution of the electron beam current density on the output foil ± 15%. It was found that emission drop of both type of cathodes, during the operation at the high repetition rate (100 pps) is substantial at the beginning of the process, and then proceeds rather slowly that allows for continuous operation up to 40 h. Experiments showed that linear dependence of the voltage and a signal from the pin-diode remains within the range of the charge voltage 45-65 kV. Thus, voltage increases from 690 to 950 kV, and the signal from the pin-diode - from (2,8-4,6)*104 Gy/s. It allows to select electron energy quite precisely with consideration of the radiation technology requirements.

Improvements in or relating to the protection of thermoelectric devices against shocks and accelerations

International Nuclear Information System (INIS)

Brown, M.H.; Myatt, J.

1979-01-01

Heart pacemakers are protected against shock and acceleration by surrounding the heat source, but not in contact with the source or the thermoelectric unit, with a plurity of spring fingers. These arrest the radioactive source in the event of movement on its resilient mounting of the thermoelectric unit relative to the casing in excess of a predetermined amount. (UK)

Eutectic mixtures of some fatty acids for latent heat storage: Thermal properties and thermal reliability with respect to thermal cycling

International Nuclear Information System (INIS)

Sari, Ahmet

2006-01-01

Accelerated thermal cycle tests have been conducted to study the change in melting temperatures and latent heats of fusion of the eutectic mixtures of lauric acid (LA)-myristic acid (MA), lauric acid (LA)-palmitic acid (PA) and myristic acid (MA)-stearic acid (SA) as latent heat storage materials. The thermal properties of these materials were determined by the differential scanning calorimetry (DSC) analysis method. The thermal reliability of the eutectic mixtures after melt/freeze cycles of 720, 1080 and 1460 was also evaluated using the DSC curves. The accelerated thermal cycle tests indicate that the melting temperatures usually tend to decrease, and the variations in the latent heats of fusion are irregular with increasing number of thermal cycles. Moreover, the probable reasons for the change in thermal properties of the eutectic mixtures after repeated thermal cycles were investigated. Fourier Transform Infrared (FT-IR) spectroscopic analysis indicates that the accelerated melt/freeze processes do not cause any degradation in the chemical structure of the mixtures. The change in thermal properties of the eutectic mixtures with increasing number of thermal cycles is only because of the presence of certain amounts of impurities in the fatty acids used in their preparation. It is concluded that the tested eutectic mixtures have reasonable thermal properties and thermal reliability as phase change materials (PCMs) for latent heat storage in any solar heating applications that include a four year utilization period

Can low energy electrons affect high energy physics accelerators?

CERN Document Server

Cimino, R; Furman, M A; Pivi, M; Ruggiero, F; Rumolo, Giovanni; Zimmermann, Frank

2004-01-01

The properties of the electrons participating in the build up of an electron cloud (EC) inside the beam-pipe have become an increasingly important issue for present and future accelerators whose performance may be limited by this effect. The EC formation and evolution are determined by the wall-surface properties of the accelerator vacuum chamber. Thus, the accurate modeling of these surface properties is an indispensible input to simulation codes aimed at the correct prediction of build-up thresholds, electron-induced instability or EC heat load. In this letter, we present the results of surface measurements performed on a prototype of the beam screen adopted for the Large Hadron Collider (LHC), which presently is under construction at CERN. We have measured the total secondary electron yield (SEY) as well as the related energy distribution curves (EDC) of the secondary electrons as a function of incident electron energy. Attention has been paid, for the first time in this context, to the probability at whic...

Disposition of nuclear waste using subcritical accelerator-driven systems

International Nuclear Information System (INIS)

Venneri, F.; Li, N.; Williamson, M.; Houts, M.; Lawrence, G.

1998-01-01

Spent fuel from nuclear power plants contains large quantities of Pu, other actinides, and fission products (FP). This creates challenges for permanent disposal because of the long half-lives of some isotopes and the potential for diversion of the fissile material. Two issues of concern for the US repository concept are: (1) long-term radiological risk peaking tens-of-thousands of years in the future; and (2) short-term thermal loading (decay heat) that limits capacity. An accelerator-driven neutron source can destroy actinides through fission, and can convert long-lived fission products to shorter-lived or stable isotopes. Studies over the past decade have established that accelerator transmutation of waste (ATW) can have a major beneficial impact on the nuclear waste problem. Specifically, the ATW concept the authors are evaluating: (1) destroys over 99.9% of the actinides; (2) destroys over 99.9% of the Tc and I; (3) separates Sr-90 and Cs-137; (4) separates uranium from the spent fuel; (5) produces electric power

Development of a novel method for the exploration of the thermal response of superfluid helium cooled superconducting cables to pulse heat loads

NARCIS (Netherlands)

Winkler, Tiemo; Koettig, T.; van Weelderen, R.; Bremer, J.; ter Brake, Hermanus J.M.

2015-01-01

Management of transient heat deposition in superconducting magnets and its extraction from the aforementioned is becoming increasingly important to bring high energy particle accelerator performance to higher beam energies and intensities. Precise knowledge of transient heat deposition phenomena in

A conceptual design of the DTL-SDTL for the JAERI high intensity proton accelerator

Energy Technology Data Exchange (ETDEWEB)

Ino, Hiroshi; Kabeya, Zenzaburo [Mitsubishi Heavy Industries Ltd., Tokyo (Japan); Chishiro, Etsuji; Ouchi, Nobuo; Hasegawa, Kazuo; Mizumoto, Motoharu

1998-08-01

A high intensity proton linear accelerator with an energy of 1.5 GeV and an average beam power of 8 MW has been proposed for the Neutron Science Project (NSP) at JAERI. This linac starts with radio-frequency quadrupole (RFQ) linac, which is followed by a drift-tube linac (DTL), separated-type DTL (SDTL), and a superconducting structure. In this report, we focus on the DTL and SDTL part of the accelerator. The DTL accelerates the beam from 2 to 51 MeV, and SDTL accelerates the beam from 51 to 10 MeV. Since the main features of the requirement for the DTL-SDTL are high peak current ({approx}30 mA) and a high-duty factor ({approx}CW), the conceptual design should be determined not only based on the result of a beam-dynamics calculation, but by careful study of the cooling problems. The design processes of the DTL-SDTL and the matching sections (RFQ to DTL, CW-Pulse merge section, and SDTL to SCC) and the result of a heat transfer analysis of DTL are described. (author)

Plasma particle accelerators

International Nuclear Information System (INIS)

Dawson, J.M.

1988-01-01

The Superconducting Supercollider (SSC) will require an 87-kilometer accelerator ring to boost particles to 40 TeV. The SSC's size is due in part to the fact that its operating principle is the same one that has dominated accelerator design for 50 years: it guides particles by means of magnetic fields and propels them by strong electric fields. If one were to build an equally powerful but smaller accelerator, one would need to increase the strength of the guiding and propelling fields. Actually, however, conventional technology may not be able to provide significant increases in field strength. There are two reasons. First, the forces from magnetic fields are becoming greater than the structural forces that hold a magnetic material together; the magnets that produce these fields would themselves be torn apart. Second, the energy from electric fields is reaching the energies that bind electrons to atoms; it would tear electrons from nuclei in the accelerator's support structures. It is the electric field problem that plasma accelerators can overcome. Plasma particle accelerators are based on the principle that particles can be accelerated by the electric fields generated within a plasma. Because the plasma has already been ionized, plasma particle accelerators are not susceptible to electron dissociation. They can in theory sustain accelerating fields thousands of times stronger that conventional technologies. So far two methods for creating plasma waves for accelerators have been proposed and tested: the wakefield and the beat wave. Although promising electric fields have been produced, more research is necessary to determine whether plasma particle accelerators can compete with the existing accelerators. 7 figs

Particle acceleration in regions of magnetic flux emergence: a statistical approach using test-particle- and MHD-simulations

Science.gov (United States)

Vlahos, Loukas; Archontis, Vasilis; Isliker, Heinz

We consider 3D nonlinear MHD simulations of an emerging flux tube, from the convection zone into the corona, focusing on the coronal part of the simulations. We first analyze the statistical nature and spatial structure of the electric field, calculating histograms and making use of iso-contour visualizations. Then test-particle simulations are performed for electrons, in order to study heating and acceleration phenomena, as well as to determine HXR emission. This study is done by comparatively exploring quiet, turbulent explosive, and mildly explosive phases of the MHD simulations. Also, the importance of collisional and relativistic effects is assessed, and the role of the integration time is investigated. Particular aim of this project is to verify the quasi- linear assumptions made in standard transport models, and to identify possible transport effects that cannot be captured with the latter. In order to determine the relation of our results to Fermi acceleration and Fokker-Planck modeling, we determine the standard transport coefficients. After all, we find that the electric field of the MHD simulations must be downscaled in order to prevent an un-physically high degree of acceleration, and the value chosen for the scale factor strongly affects the results. In different MHD time-instances we find heating to take place, and acceleration that depends on the level of MHD turbulence. Also, acceleration appears to be a transient phenomenon, there is a kind of saturation effect, and the parallel dynamics clearly dominate the energetics. The HXR spectra are not yet really compatible with observations, we have though to further explore the scaling of the electric field and the integration times used.

Modeling drug release from functionalized magnetic nanoparticles actuated by non-heating low frequency magnetic field

Energy Technology Data Exchange (ETDEWEB)

Golovin, Y., E-mail: nano@tsutmb.ru [M.V. Lomonosov Moscow State University, School of Chemistry (Russian Federation); Golovin, D. [G.R. Derzhavin Tambov State University (Russian Federation); Klyachko, N.; Majouga, A.; Kabanov, A. [M.V. Lomonosov Moscow State University, School of Chemistry (Russian Federation)

2017-02-15

Various plausible acceleration mechanisms of drug release from nanocarriers composed of a single-domain magnetic nanoparticle core with attached long macromolecule chains activated by low frequency non-heating alternating magnetic field (AMF) are discussed. The most important system characteristics affecting the AMF exposure impact are determined. Impact of several reasonable mechanisms is estimated analytically or obtained using numerical modeling. Some conditions providing manifold release acceleration as a result from exposure in AMF are found.

Modeling drug release from functionalized magnetic nanoparticles actuated by non-heating low frequency magnetic field

International Nuclear Information System (INIS)

Golovin, Y.; Golovin, D.; Klyachko, N.; Majouga, A.; Kabanov, A.

2017-01-01

Various plausible acceleration mechanisms of drug release from nanocarriers composed of a single-domain magnetic nanoparticle core with attached long macromolecule chains activated by low frequency non-heating alternating magnetic field (AMF) are discussed. The most important system characteristics affecting the AMF exposure impact are determined. Impact of several reasonable mechanisms is estimated analytically or obtained using numerical modeling. Some conditions providing manifold release acceleration as a result from exposure in AMF are found.

Experimental investigation of the thermal hydraulics in lead bismuth eutectic-helium experimental loop of an accelerator-driven system

Energy Technology Data Exchange (ETDEWEB)

Xi, Wenxuan; Wang, Yong Wei; Li, Xun Feng; Huai, Xiulan; Cal, Jun [Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing (China)

2016-10-15

The heat transfer characteristics between liquid lead bismuth eutectic (LBE) and helium are of great significance for the two-loop cooling system based on an accelerator-driven system (ADS). This paper presents an experimental study on the resistance characteristics and heat transfer performance in a LBE-helium experimental loop of ADS. Pressure drops in the LBE loop, the main heat transfer, and the coupled heat transfer characteristics between LBE and helium are investigated experimentally. The temperature of LBE has a significant effect on the LBE thermo-physical properties, and is therefore considered in the prediction of pressure drops. The results show that the overall heat transfer coefficient increases with the increasing helium flow rate and the decreasing inlet temperature of helium. Increasing the LBE Reynolds number and LBE inlet temperature promotes the heat transfer performance of main heat transfer and thus the overall heat transfer coefficient. The experimental results give an insight into the flow and heat transfer properties in a LBE-helium heat exchanger and are helpful for the optimization of an ADS system design.

Volatile profile of Madeira wines submitted to traditional accelerated ageing.

Science.gov (United States)

Pereira, Vanda; Cacho, Juan; Marques, José C

2014-11-01

The evolution of monovarietal fortified Madeira wines forced-aged by traditional thermal processing (estufagem) were studied in terms of volatiles. SPE extracts were analysed by GC-MS before and after heating at 45 °C for 3 months (standard) and at 70 °C for 1 month (overheating). One hundred and ninety volatile compounds were identified, 53 of which were only encountered in baked wines. Most chemical families increased after standard heating, especially furans and esters, up to 61 and 3-fold, respectively. On the contrary, alcohols, acetates and fatty acids decreased after heating. Varietal aromas, such as Malvasia's monoterpenic alcohols were not detected after baking. The accelerated ageing favoured the development of some volatiles previously reported as typical aromas of finest Madeira wines, particularly phenylacetaldeyde, β-damascenone and 5-ethoxymethylfurfural. Additionally, ethyl butyrate, ethyl 2-methylbutyrate, ethyl caproate, ethyl isovalerate, guaiacol, 5-hydroxymethylfurfural and γ-decalactone were also found as potential contributors to the global aroma of baked wines. Copyright © 2014 Elsevier Ltd. All rights reserved.

Molecular ion acceleration using tandem accelerator

Energy Technology Data Exchange (ETDEWEB)

Saito, Yuichi; Mizuhashi, Kiyoshi; Tajima, Satoshi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

1996-12-01

In TIARA compound beam radiation system, cluster beams have been produced using 3 MV tandem accelerator (9SDH-2) to supply them to various radiation on injection experiments. Till now, productions of C{sub 2-8}, Si{sub 2-4} and O{sub 2} and their accelerations up to 6 MeV have been succeeded. This study aimed at production and acceleration of B{sub 2-4} and LiF. Anion clusters were produced using the conventional ion source of cesium sputter type. The proportions of atoms, molecules and clusters elicited from the ion source were varied depending on the material`s properties and the operating conditions of ion source such as sample temperature, sputter voltage and the shape of sample. The anion clusters were accelerated toward the high voltage terminal in the center of tandem accelerator, leading to cations through losing their electrons by the collision to N{sub 2} gas in a charge conversion cell at the terminal. Positively charged cluster ions could be obtained by modulating the pressure of N{sub 2} gas. Thus, B{sub 2} (64 nA), B{sub 3} (4.4 nA) and B{sub 4} (2.7 nA) have been produced and their maximum survival probabilities were higher than those of carbon or silicon clusters. In addition, the relationship between beam current and gas pressure was investigated for Bn (n = 2-4) and LiF. (M.N.)

Temperature control system for the study of single event effects in integrated circuits using a cyclotron accelerator

Energy Technology Data Exchange (ETDEWEB)

Bakerenkov, A.S., E-mail: as_bakerenkov@list.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Belyakov, V.V. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Kozyukov, A.E. [Joint-Stock Company Institute of Space Device Engineering (JSC ISDE), Moscow (Russian Federation); Pershenkov, V.S.; Solomatin, A.V.; Shurenkov, V.V. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation)

2015-02-11

The temperature control system for the study of single event disruptions produced by hard ion impacts in integrated circuits is described. Heating and cooling of the irradiated device are achieved using thermoelectric modules (Peltier modules). The thermodynamic performance of the system is estimated. The technique for the numerical estimation of the main parameters of the temperature control system for cooling and heating is considered. The results of a test of the system in a vacuum cell of an accelerator are presented.

Temperature control system for the study of single event effects in integrated circuits using a cyclotron accelerator

International Nuclear Information System (INIS)

Bakerenkov, A.S.; Belyakov, V.V.; Kozyukov, A.E.; Pershenkov, V.S.; Solomatin, A.V.; Shurenkov, V.V.

2015-01-01

The temperature control system for the study of single event disruptions produced by hard ion impacts in integrated circuits is described. Heating and cooling of the irradiated device are achieved using thermoelectric modules (Peltier modules). The thermodynamic performance of the system is estimated. The technique for the numerical estimation of the main parameters of the temperature control system for cooling and heating is considered. The results of a test of the system in a vacuum cell of an accelerator are presented

TeV/m Nano-Accelerator: Current Status of CNT-Channeling Acceleration Experiment

Energy Technology Data Exchange (ETDEWEB)

Shin, Young Min [Northern Illinois U.; Lumpkin, Alex H. [Fermilab; Thangaraj, Jayakar Charles [Fermilab; Thurman-Keup, Randy Michael [Fermilab; Shiltsev, Vladimir D. [Fermilab

2014-09-17

Crystal channeling technology has offered various opportunities in the accelerator community with a viability of ultrahigh gradient (TV/m) acceleration for future HEP collider. The major challenge of channeling acceleration is that ultimate acceleration gradients might require a high power driver in the hard x-ray regime (~ 40 keV). This x-ray energy exceeds those for x-rays as of today, although x-ray lasers can efficiently excite solid plasma and accelerate particles inside a crystal channel. Moreover, only disposable crystal accelerators are possible at such high externally excited fields which would exceed the ionization thresholds destroying the atomic structure, so acceleration will take place only in a short time before full dissociation of the lattice. Carbon-based nanostructures have great potential with a wide range of flexibility and superior physical strength, which can be applied to channeling acceleration. This paper presents a beam- driven channeling acceleration concept with CNTs and discusses feasible experiments with the Advanced Superconducting Test Accelerator (ASTA) in Fermilab.

He II Heat Exchanger Test Unit for the LHC Inner Triplet

CERN Document Server

Blanco-Viñuela, E; Huang, Y; Nicol, T H; Peterson, T; Van Weelderen, R

2002-01-01

The Inner Triplet Heat Exchanger Test Unit (IT-HXTU) is a 30-m long thermal model designed at Fermilab, built in US industry, fully automated and tested at CERN as part of the US LHC program to develop the LHC Interaction Region quadrupole system. The cooling scheme of the IT-HXTU is based on heat exchange between stagnant pressurized He II in the magnet cold mass and saturated He II (two-phase) flowing in a heat exchanger located outside of and parallel to the cold mass. The purposes of this test are, among others, to validate the proposed cooling scheme and to define an optimal control strategy to be implemented in the future LHC accelerator. This paper discusses the results for the heat exchanger test runs and emphasizes the thermal and hydraulic behavior of He II for the inner triplet cooling scheme.

Accelerator mass spectrometry at the Rossendorf 5 MV tandem accelerator

International Nuclear Information System (INIS)

Friedrich, M.; Buerger, W.; Curian, H.; Hartmann, B.; Hentschel, E.; Matthes, H.; Probst, W.; Seidel, M.; Turuc, S.; Hebert, D.; Rothe, T.; Stolz, W.

1992-01-01

The Rossendorf electrostatic accelerators (5 MV tandem accelerator and single ended 2 MV van de Graaff accelerator) are already used for ion beam analysis. The existing methods (RBS, PIXE, ERDA, NRA, nuclear microprobe and external beam) will be completed by introduction of Accelerator Mass Spectrometry (AMS). A short description of the Rossendorf AMS system is given and first experimental results are presented. (R.P.) 4 refs.; 6 figs

Truck acceleration behavior study and acceleration lane length recommendations for metered on-ramps

Directory of Open Access Journals (Sweden)

Guangchuan Yang

2016-10-01

Full Text Available This paper investigated the actual truck acceleration capability at metered on-ramps. Truck acceleration performance data were collected through a video-based data collection method. A piecewise constant acceleration model was employed to capture truck acceleration characteristics. It was found that the existing acceleration length will affect truck drivers’ acceleration behavior. At the taper type ramp that has limited acceleration distance, acceleration profile indicated a decreasing trend with distance. While for the ramp with an auxiliary lane that has sufficient acceleration distance, it was found that the acceleration behavior is to have a high acceleration rate in the beginning, then acceleration rate decrease with speed increase, and high acceleration rate again as drivers approach the merging area. Field data show that the truck acceleration performance data documented in the ITE’s (Institute of Transportation Engineers “Traffic Engineering Handbook” are much lower than the field collected data. Also, based on the regression analysis of speed versus distance profiles, it was found that the AASHTO’s (American Association of State Highway and Transportation Officials Green Book acceleration length design guidance is insufficient to accommodate trucks at metered on-ramps. The required acceleration lengths for medium and heavy trucks are approximately 1.3 and 1.6 times of the Green Book design guideline, respectively.

Conceptual design of multi-purpose accelerator-driven transmutation test facility

International Nuclear Information System (INIS)

Hirota, Koichi; Hida, Kenzo; Yokobori, Hitoshi; Kamishima, Yoshio

1999-01-01

The Japan Atomic Energy Research Institute (JAERI) has been developing a concept of accelerator-driven transmutation system using a high-power proton linac. To demonstrate the technical feasibility of this concept, accelerator-driven spallation experiments will be necessary. We believe our proposal of a multi-purpose test facility is a promising concept to clarify its feasibility from the basic neutronics and engineering standpoint. The main feature of our initial proposal is using an inclined beam injection. It enables to simplify the head of the test vessel as well as to facilitate easy replacing of the beam window and the testing device containing the test specimen, and also this system will minimize the complexity of the vessel head and surrounding structures. Next proposal is using an ordinary overhead beam injection system and is modified to be simple structural concept of the test vessel from inclined beam injection. At the first step, the basic neutronics experiments will be performed. At this step, the test device and the cooling device are simpler ones, due to only small heat will be generated. Then we plan using a gas cooling. At the following steps, the test device and the vessel internal structures will be remodeled or remade to adjust to the test purposes, if necessary. At these steps, target material tests and thermal hydraulic tests using some liquid metal coolants will be done. In this case, the natural circulation cooling will be done. To verify the transmutation technology, a larger heat will be generated, so a forced coolant circulation system will be installed in the test vessel. This system consists of a heat exchanger and a circulation pump. The vessel internal structure will be remade. Doing such step-wise remaking, initial construction cost of the proposed test facility will be expected to be reasonable. (author)

Desloratadine analysis: as a pharmaceutical preparation and after accelerating ageing

Directory of Open Access Journals (Sweden)

Bober Katarzyna

2015-09-01

Full Text Available Desloratadine is a biologically active compound that is not described in the Polish Pharmacopoeia IX, hence, its study is particular important. The aim of this work was to establish a procedure for desloratadine analysis by way of HPTLC in combination with densitometry, so as to be able to ascertain its presence and degree of presence within pharmaceutical preparations. In our work, a mixture of ethyl acetate, n-butanol, ammonia and methanol was used as the mobile phase. Moreover, HPTLC plates precoated with silica gel 60F254 were also employed. The proposed method was tested and subsequently validated. Spectrodensitometric analysis was then performed to determine the optimal wavelength for the quantitative determination (λ=276 nm, and following this, a quantitative analysis of desloratadine within certain pharmaceutical preparations was performed. Our research also took into consideration an analysis of the products of desloratadine decomposition that come about as a result of the accelerated aging of its solutions. The employed procedure for accelerating the aging of such desloratadine solutions consisted of heating these at 40℃ and then irradiating the solution surfaces with UV light. The changing color of these solutions after 2 hours of exposure served to indicate that degradation had occurred. Of note: as a result of irradiation with UV light, desloratadine content was seen to decrease with time, declining to almost zero after 30 hours. However, heating a solution of desloratadine alone did not induce a change in its content. Solutions of desloratadine that had previously undergone irradiation and heating were also analyzed to ascertain whether new substances were present. For this purpose, the GC-MS process was employed. As a result of this procedure, the spectrum of the solution after aging showed the presence of several new peaks that displayed retention several times larger and smaller than the normal desloratadine peak.

Probing electron acceleration and x-ray emission in laser-plasma accelerators

International Nuclear Information System (INIS)

Thaury, C.; Ta Phuoc, K.; Corde, S.; Brijesh, P.; Lambert, G.; Malka, V.; Mangles, S. P. D.; Bloom, M. S.; Kneip, S.

2013-01-01

While laser-plasma accelerators have demonstrated a strong potential in the acceleration of electrons up to giga-electronvolt energies, few experimental tools for studying the acceleration physics have been developed. In this paper, we demonstrate a method for probing the acceleration process. A second laser beam, propagating perpendicular to the main beam, is focused on the gas jet few nanosecond before the main beam creates the accelerating plasma wave. This second beam is intense enough to ionize the gas and form a density depletion, which will locally inhibit the acceleration. The position of the density depletion is scanned along the interaction length to probe the electron injection and acceleration, and the betatron X-ray emission. To illustrate the potential of the method, the variation of the injection position with the plasma density is studied

Effect of heat transfer on unsteady MHD flow of blood in a permeable vessel in the presence of non-uniform heat source

Directory of Open Access Journals (Sweden)

A. Sinha

2016-09-01

Full Text Available This paper presents a theoretical analysis of blood flow and heat transfer in a permeable vessel in the presence of an external magnetic field. The unsteadiness in the coupled flow and temperature fields is considered to be caused due to the time-dependent stretching velocity and the surface temperature of the vessel. The non-uniform heat source/sink effect on blood flow and heat transfer is taken into account. This study is of potential value in the clinical treatment of cardiovascular disorders accompanied by accelerated circulation. The problem is treated mathematically by reducing it to a system of coupled nonlinear differential equations, which have been solved by using similarity transformation and boundary layer approximation. The resulting nonlinear coupled ordinary differential equations are solved numerically by using an implicit finite difference scheme. Computational results are obtained for the velocity, temperature, the skin-friction coefficient and the rate of heat transfer in the vessel. The estimated results are compared with another analytical study reported earlier in scientific literatures. The present study reveals that the heat transfer rate is enhanced as the value of the unsteadiness parameter increases, but it reduces as the space-dependence parameter for heat source/sink increases.

Microelectromechanical acceleration-sensing apparatus

Science.gov (United States)

Lee, Robb M [Albuquerque, NM; Shul, Randy J [Albuquerque, NM; Polosky, Marc A [Albuquerque, NM; Hoke, Darren A [Albuquerque, NM; Vernon, George E [Rio Rancho, NM

2006-12-12

An acceleration-sensing apparatus is disclosed which includes a moveable shuttle (i.e. a suspended mass) and a latch for capturing and holding the shuttle when an acceleration event is sensed above a predetermined threshold level. The acceleration-sensing apparatus provides a switch closure upon sensing the acceleration event and remains latched in place thereafter. Examples of the acceleration-sensing apparatus are provided which are responsive to an acceleration component in a single direction (i.e. a single-sided device) or to two oppositely-directed acceleration components (i.e. a dual-sided device). A two-stage acceleration-sensing apparatus is also disclosed which can sense two acceleration events separated in time. The acceleration-sensing apparatus of the present invention has applications, for example, in an automotive airbag deployment system.

Channel-accelerating gap interaction and beam acceleration and transport experiments with the recirculating linear accelerator (RLA)

International Nuclear Information System (INIS)

Mazarakis, M.G.; Smith, D.L.; Poukey, J.W.; Wagner, J.S.; Bennett, L.F.; Olson, W.R.; Turman, B.N.; Prestwich, K.R.; Wells, J.; Struve, K.

1992-01-01

The lifetime of the Ion Focusing Regime (IFR) channel following the pulsing of the post-accelerating gaps is critical for open-ended low energy devices. It dictates the number of allowable beam recirculations through the gaps. In the case of a closed racetrack configuration, it is significant but not as critical, since the presence of the electron beam focuses the ions and lengthens the lifetime of the ion channel. The authors have experimentally established that pulsing an accelerating gap perturbs the IFR channel. However for the parameters studied, the lifetime is long enough to allow at least four beam recirculations in a spiral device. In addition transparent grids of cusp fields positioned upstream and downstream from the gaps prevent them from perturbing the IFR channel. Experiments were performed with and without injected electron beams. For the experiments investigating the IFR channel interaction with the accelerating gap, the injector was removed and the beam line was extended downstream and upstream from the accelerating cavity. Only the first straight section of the RLA with one accelerating cavity (ET-2) was utilized. The acceleration and transport experiments were performed utilizing two injectors: first the low energy 1.3-MV Isolated Blumlein (IB) injector and most recently the new 4-MV 20-kA injector. Beams of 6--20 kA current were produced and successfully transported and accelerated through the ET-2 post-accelerating gap. For both injectors an apertured non-immersed ion-focused foilless diode was selected among various options. It is the simplest and easiest to operate and can be adjusted to provide variable beam impedance loads to the injector. The transport efficiencies were 90% for the low energy injector and 100% for the new 4-MV injector. The beam Gaussian profile and radius (5 mm) remain the same through acceleration. Experimental results will be presented and compared with numerical simulations

Air pollution prevention through urban heat island mitigation: An update on the urban heat island pilot project

Energy Technology Data Exchange (ETDEWEB)

Gorsevski, V.; Taha, H.; Quattrochi, D.; Luvall, J.

1998-07-01

Urban heat islands increase the demand for cooling energy and accelerate the formation of smog. They are created when natural vegetation is replaced by heat-absorbing surfaces such as building roofs and walls, parking lots, and streets. Through the implementation of measures designed to mitigate the urban heat island, communities can decrease their demand for energy and effectively cool the metropolitan landscape. In addition to the economic benefits, using less energy leads to reductions in emission of CO{sub 2}--a greenhouse gas--as well as ozone (smog) precursors such as NOx and VOCs. Because ozone is created when NOx and VOCs photochemically combine with heat and solar radiation, actions taken to lower ambient air temperature can significantly reduce ozone concentrations in certain areas. Measures to reverse the urban heat island include afforestation and the widespread use of highly reflective surfaces. To demonstrate the potential benefits of implementing these measures, EPA has teamed up with NASA and LBNL to initiate a pilot project with three US cities. As part of the pilot, NASA will use remotely-sensed data to quantify surface temperature, albedo, the thermal response number and NDVI vegetation of each city. This information will be used by scientists at Lawrence Berkeley National Laboratory (LBNL) along with other data as inputs to model various scenarios that will help quantify the potential benefits of urban heat island mitigation measures in terms of reduced energy use and pollution. This paper will briefly describe this pilot project and provide an update on the progress to date.

Accelerator reliability workshop

International Nuclear Information System (INIS)

Hardy, L.; Duru, Ph.; Koch, J.M.; Revol, J.L.; Van Vaerenbergh, P.; Volpe, A.M.; Clugnet, K.; Dely, A.; Goodhew, D.

2002-01-01

About 80 experts attended this workshop, which brought together all accelerator communities: accelerator driven systems, X-ray sources, medical and industrial accelerators, spallation sources projects (American and European), nuclear physics, etc. With newly proposed accelerator applications such as nuclear waste transmutation, replacement of nuclear power plants and others. Reliability has now become a number one priority for accelerator designers. Every part of an accelerator facility from cryogenic systems to data storage via RF systems are concerned by reliability. This aspect is now taken into account in the design/budget phase, especially for projects whose goal is to reach no more than 10 interruptions per year. This document gathers the slides but not the proceedings of the workshop

Accelerator reliability workshop

Energy Technology Data Exchange (ETDEWEB)

Hardy, L; Duru, Ph; Koch, J M; Revol, J L; Van Vaerenbergh, P; Volpe, A M; Clugnet, K; Dely, A; Goodhew, D

2002-07-01

About 80 experts attended this workshop, which brought together all accelerator communities: accelerator driven systems, X-ray sources, medical and industrial accelerators, spallation sources projects (American and European), nuclear physics, etc. With newly proposed accelerator applications such as nuclear waste transmutation, replacement of nuclear power plants and others. Reliability has now become a number one priority for accelerator designers. Every part of an accelerator facility from cryogenic systems to data storage via RF systems are concerned by reliability. This aspect is now taken into account in the design/budget phase, especially for projects whose goal is to reach no more than 10 interruptions per year. This document gathers the slides but not the proceedings of the workshop.

Turbulent heavy liquid metal heat transfer along a heated rod in an annular cavity

International Nuclear Information System (INIS)

Lefhalm, C.-H.; Tak, N.-I.; Piecha, H.; Stieglitz, R.

2004-01-01

Heavy liquid metals (HLM) are considered as coolant and spallation material in accelerator driven systems (ADS), because of their good molecular heat conductivity. This property leads to a separation of the spatial extension of thermal and viscous boundary layers. Commercially available computational fluid dynamic codes (CFD) assume an analogy of momentum and energy transfer, which is problematic for liquid metals flow. Therefore, benchmark experiments are required, in order to validate codes or modify existing models used therein. Within this article an experimental and numerical study of a thermally developing turbulent lead bismuth (PbBi) flow along a uniformly heated rod in a circular tube is presented. Local temperatures and velocity distributions are measured using thermocouples and Pitot tubes. The data are compared to simulation results computed with the CFX code package. The measured velocity profiles coincide nearly perfect with the simulation results. However, discrepancies up to 7% between the measured and computed temperatures appear. A minor part of the deviations can be explained by the imperfect experimental set-up. But, the measured shape of the thermal boundary is different to the calculated one, indicating the inadequateness of the presently used models describing the turbulent heat transport within the thermal boundary layer

Future accelerator technology

International Nuclear Information System (INIS)

Sessler, A.M.

1986-05-01

A general discussion is presented of the acceleration of particles. Upon this foundation is built a categorization scheme into which all accelerators can be placed. Special attention is devoted to accelerators which employ a wake-field mechanism and a restricting theorem is examined. It is shown how the theorem may be circumvented. Comments are made on various acceleration schemes

Accelerator conceptual design and needs of nuclear data for boron neutron capture therapy

International Nuclear Information System (INIS)

Sasaki, Makoto; Yamanaka, Toshiyuki; Yokobori, Hitoshi

1999-01-01

An optimization study has been made on an accelerator-based facility for the boron neutron capture therapy. The energy of the incident proton and the arrangement of the moderator assemblies are optimized. The beam current and the accelerating voltage are determined so that the accelerator power becomes minimum. The proposed facility is equipped with a 2.5 MeV proton accelerator of 10-25 mA, a lithium target, and a heavy water moderator contained in an aluminum tank. Each of these equipment is feasible, if proper R and D works have been done. Our new design requires the beam power of less than a hundred kW for the accelerator, although that of our previous design was 1 MW. The reduction of the beam power makes the cooling system for the target much simpler. The essential issues for realization of this concept are long-life lithium targets under high heat flux and high current proton accelerators with average currents of more than 10 mA. It is necessary for the reasonable design of a small-sized and low cost facility to get good accuracy nuclear reaction data. Especially, the latest Li/Be(p, n) neutron yield data in a range of threshold energy - few MeV are required for exact evaluation of neutron energy spectrum used therapy. And damage data by low energy proton beam are also important to evaluate integrity of target material. (author)

Detection of the Acceleration Site in a Solar Flare

Science.gov (United States)

Fleishman, Gregory D.; Kontar, E. P.; Nita, G. M.; Gary, D. E.

2011-05-01

We report the observation of an unusual cold, tenuous solar flare (ApJL, v. 731, p. L19, 2011), which reveals itself via numerous and prominent non-thermal manifestations, while lacking any noticeable thermal emission signature. RHESSI hard X-rays and 0.1-18 GHz radio data from OVSA and Phoenix-2 show copious electron acceleration (1035 electrons per second above 10 keV) typical for GOES M-class flares with electrons energies up to 100 keV, but GOES temperatures not exceeding 6.1 MK. The HXR footpoints and coronal radio sources belong, supposedly, to a single magnetic loop, which departs strongly from the corresponding potential loop (obtained from a photospheric extrapolation) in agreement with the apparent need of a non-potential magnetic field structure to produce a flare. The imaging, temporal, and spectral characteristics of the flare have led us to a firm conclusion that the bulk of the microwave continuum emission from this flare was produced directly in the acceleration region. We found that the electron acceleration efficiency is very high in the flare, so almost all available thermal electrons are eventually accelerated. However, given a relatively small flaring volume and rather low thermal density at the flaring loop, the total energy release turned out to be insufficient for a significant heating of the coronal plasma or for a prominent chromospheric response giving rise to chromospheric evaporation. Some sort of stochastic acceleration process is needed to account for an approximately energy-independent lifetime of about 3 s for the electrons in the acceleration region. This work was supported in part by NSF grants AGS-0961867, AST-0908344, and NASA grants NNX10AF27G and NNX11AB49G to New Jersey Institute of Technology. This work was supported by a UK STFC rolling grant, STFC/PPARC Advanced Fellowship, and the Leverhulme Trust, UK. Financial support by the European Commission through the SOLAIRE and HESPE Networks is gratefully acknowledged.

Accelerating Inspire

CERN Document Server

AUTHOR|(CDS)2266999

2017-01-01

CERN has been involved in the dissemination of scientific results since its early days and has continuously updated the distribution channels. Currently, Inspire hosts catalogues of articles, authors, institutions, conferences, jobs, experiments, journals and more. Successful orientation among this amount of data requires comprehensive linking between the content. Inspire has lacked a system for linking experiments and articles together based on which accelerator they were conducted at. The purpose of this project has been to create such a system. Records for 156 accelerators were created and all 2913 experiments on Inspire were given corresponding MARC tags. Records of 18404 accelerator physics related bibliographic entries were also tagged with corresponding accelerator tags. Finally, as a part of the endeavour to broaden CERN's presence on Wikipedia, existing Wikipedia articles of accelerators were updated with short descriptions and links to Inspire. In total, 86 Wikipedia articles were updated. This repo...

Requirements of a proton beam accelerator for an accelerator-driven reactor

International Nuclear Information System (INIS)

Takahashi, H.; Zhao, Y.; Tsoupas, N.; An, Y.; Yamazaki, Y.

1997-01-01

When the authors first proposed an accelerator-driven reactor, the concept was opposed by physicists who had earlier used the accelerator for their physics experiments. This opposition arose because they had nuisance experiences in that the accelerator was not reliable, and very often disrupted their work as the accelerator shut down due to electric tripping. This paper discusses the requirements for the proton beam accelerator. It addresses how to solve the tripping problem and how to shape the proton beam

An LCLC resonant topology based filament power supply for 300 KeV DC accelerator

International Nuclear Information System (INIS)

Kasliwal, A.; Gauttam, V.K.; Banwari, R.; Pandit, T.G.; Thakurta, A.C.

2013-01-01

A compact, low energy dc accelerator for industrial applications requiring beam energy in the range of 100 to 300 keV is under development at Raja Ramanna Centre for Advanced Technology, Indore. The accelerator uses an indirectly heated LaB6 disc type filament of 4 mm diameter as an electron emitter which is floating at terminal voltage of the accelerator. A power supply is required to heat the filament for its full range of emission. A high frequency inverter operating at fixed frequency feeds the power to the filament through high frequency transformers and capacitive isolation column. A buck chopper controls the dc bus voltage of the inverter so as to control the terminal voltage of the filament thus controlling the beam current. This paper presents the analysis and design of the filament supply that implements a 40 kHz high order LCLC series parallel resonant inverter that utilizes the reflected capacitance of the HV transformer and capacitive isolation column as its tank circuit component. The operating characteristics and analysis of series resonant (SRC), parallel resonant (PRC) and series parallel (SPRC) resonant converters have been reported for fixed frequency operation. It has been shown that SPRC takes the advantage of both SRC and PRC curtailing their disadvantages. Hence a series parallel LCLC combination has been used as it gives the advantage of low device currents and a better load regulation. (author)

Assessment of CHF enhancement mechanisms in a curved, rectangular channel subjected to concave heating

International Nuclear Information System (INIS)

Sturgis, J.C.; Mudawar, I.

1999-01-01

An experimental study was undertaken to examine the enhancement in critical heat flux (CHF) provided by streamwise curvature. Curved and straight rectangular flow channels were fabricated with identical 5.0 x 2.5 mm cross sections and heated lengths of 101.6 mm in which the heat was applied to only one wall--the concave wall (32.3 mm radius) in the curved channel and a side wall in the straight. Tests were conducted using FC-72 liquid with mean inlet velocity and outlet subcooling of 0.25 to 10 m s -1 and 3 to 29 C, respectively. Centripetal acceleration for curved flow reached 315 times earth's gravitational acceleration. Critical heat flux was enhanced due to flow curvature at all conditions but the enhancement decreased with increasing subcooling. For near-saturated conditions, the enhancement was approximately 60% while for highly subcooled flow it was only 20%. The causes for the enhancement were identified as (1) increased pressure on the liquid-vapor interface at wetting fronts, (2) buoyancy forces and (3) increased subcooling at the concave wall. Flow visualization tests were conducted in transparent channels to explore the role of buoyancy forces in enhancing the critical heat flux. These forces were observed to remove vapor from the concave wall and distribute it throughout the cross section. Vapor removal was only effective at near-saturated conditions, yielding the observed substantial enhancement in CHF relative to the straight channel

North–South debate on district heating: Evidence from a household survey

International Nuclear Information System (INIS)

Guo, Jin; Huang, Ying; Wei, Chu

2015-01-01

There has been a long debate on whether South China should supply district heating for the residential sector, a system that is widely used in North China. The major concern is that it may further accelerate China's energy demand. Using a unique urban household level dataset, the China Residential Energy Consumption Survey (CRECS), we investigate residential energy consumption for heating and examine the energy intensity and energy cost of distributed heating in South China and district heating in North China during the 2012 heating season. Our results show that the total energy consumption for distributed heating system users in southern cities is significantly lower than for users of district heating systems in northern cities. However, when accounting for the heating area and heating season, the distributed heating households in the South consumed 32% more energy and paid 189% higher cost per unit area and per hour, but had lower comfort than district heating users in the North. These findings suggest promoting the district heating market in appropriate areas in South China. This not only can improve residential welfare, but also can indirectly reduce energy consumption and financial burdens. - Highlights: • The debate on whether Southern China apply district heating is present. • The household data in 2012 is used to compare the energy efficient and cost. • South resident use more energy and higher cost but less comfort than North. • Government should not prevent the district heating market.

SALOME: An Accelerator for the Practical Course in Accelerator Physics

OpenAIRE

Miltchev, Velizar; Riebesehl, Daniel; Roßbach, Jörg; Trunk, Maximilian; Stein, Oliver

2014-01-01

SALOME (Simple Accelerator for Learning Optics and the Manipulation of Electrons) is a short low energy linear electron accelerator built by the University of Hamburg. The goal of this project is to give the students the possibility to obtain hands-on experience with the basics of accelerator physics. In this contribution the layout of the device will be presented. The most important components of the accelerator will be discussed and an overview of the planned demonstration experiments will ...

Superconductors for pulsed rf accelerators

International Nuclear Information System (INIS)

Campisi, I.E.; Farkas, Z.D.

1985-04-01

The choice of superconducting materials for accelerator rf cavities has been determined in the past only in part by basic properties of the superconductors, such as the critical field, and to a larger extent by criteria which include fabrication processes, surface conditions, heat transfer capabilities and so on. For cw operated cavities the trend has been toward choosing materials with higher critical temperatures and lower surface resistance, from Lead to Niobium, from Niobium to Nb 3 Sn. This trend has been dictated by the specific needs of storage ring cw system and by the relatively low fields which could be reached without breakdown. The work performed at SLAC on superconducting cavities using microsecond long high power rf pulses has shown that in Pb, Nb, and Nb 3 Sn fields close to the critical magnetic fields can be reached without magnetic breakdown

Social-emotional characteristics of gifted accelerated and non-accelerated students in the Netherlands.

Science.gov (United States)

Hoogeveen, Lianne; van Hell, Janet G; Verhoeven, Ludo

2012-12-01

In the studies of acceleration conducted so far a multidimensional perspective has largely been neglected. No attempt has been made to relate social-emotional characteristics of accelerated versus non-accelerated students in perspective of environmental factors. In this study, social-emotional characteristics of accelerated gifted students in the Netherlands were examined in relation to personal and environmental factors. Self-concept and social contacts of accelerated (n = 148) and non-accelerated (n = 55) gifted students, aged 4 to 27 (M = 11.22, SD = 4.27) were measured. Self-concept and social contacts of accelerated and non-accelerated gifted students were measured using a questionnaire and a diary, and parents of these students evaluated their behavioural characteristics. Gender and birth order were studied as personal factors and grade, classroom, teachers' gender, teaching experience, and the quality of parent-school contact as environmental factors. The results showed minimal differences in the social-emotional characteristics of accelerated and non-accelerated gifted students. The few differences we found favoured the accelerated students. We also found that multiple grade skipping does not have negative effects on social-emotional characteristics, and that long-term effects of acceleration tend to be positive. As regards the possible modulation of personal and environmental factors, we merely found an impact of such factors in the non-accelerated group. The results of this study strongly suggest that social-emotional characteristics of accelerated gifted students and non-accelerated gifted students are largely similar. These results thus do not support worries expressed by teachers about the acceleration of gifted students. Our findings parallel the outcomes of earlier studies in the United States and Germany in that we observed that acceleration does not harm gifted students, not even in the case of multiple grade skipping. On the contrary, there is a

The miniature accelerator

CERN Multimedia

Antonella Del Rosso

2015-01-01

The image that most people have of CERN is of its enormous accelerators and their capacity to accelerate particles to extremely high energies. But thanks to some cutting-edge studies on beam dynamics and radiofrequency technology, along with innovative construction techniques, teams at CERN have now created the first module of a brand-new accelerator, which will be just 2 metres long. The potential uses of this miniature accelerator will include deployment in hospitals for the production of medical isotopes and the treatment of cancer. It’s a real David-and-Goliath story.   Serge Mathot, in charge of the construction of the "mini-RFQ", pictured with the first of the four modules that will make up the miniature accelerator. The miniature accelerator consists of a radiofrequency quadrupole (RFQ), a component found at the start of all proton accelerator chains around the world, from the smallest to the largest. The LHC is designed to produce very high-intensity beams ...

Accelerators for energy

International Nuclear Information System (INIS)

Inoue, Makoto

2000-01-01

A particle accelerator is a device to consume energy but not to produce it. Then, the titled accelerator seems to mean an accelerator for using devices related to nuclear energy. For an accelerator combined to nuclear fissionable fuel, neutron sources are D-T type, (gamma, n) reaction using electron beam type spallation type, and so forth. At viewpoints of powers of incident beam and formed neutron, a spallation type source using high energy proton is told to be effective but others have some advantages by investigation on easy operability, easy construction, combustion with target, energy and directivity of neutron, and so forth. Here were discussed on an accelerator for research on accelerator driven energy system by dividing its researching steps, and on kind, energy, beam intensity, and so forth of an accelerator suitable for it. And, space electric charge effect at beam propagation direction controlled by beam intensity of cyclotron was also commented. (G.K.)

Vasculature of the hive: heat dissipation in the honey bee ( Apis mellifera) hive

Science.gov (United States)

Bonoan, Rachael E.; Goldman, Rhyan R.; Wong, Peter Y.; Starks, Philip T.

2014-06-01

Eusocial insects are distinguished by their elaborate cooperative behavior and are sometimes defined as superorganisms. As a nest-bound superorganism, individuals work together to maintain favorable nest conditions. Residing in temperate environments, honey bees ( Apis mellifera) work especially hard to maintain brood comb temperature between 32 and 36 °C. Heat shielding is a social homeostatic mechanism employed to combat local heat stress. Workers press the ventral side of their bodies against heated surfaces, absorb heat, and thus protect developing brood. While the absorption of heat has been characterized, the dissipation of absorbed heat has not. Our study characterized both how effectively worker bees absorb heat during heat shielding, and where worker bees dissipate absorbed heat. Hives were experimentally heated for 15 min during which internal temperatures and heat shielder counts were taken. Once the heat source was removed, hives were photographed with a thermal imaging camera for 15 min. Thermal images allowed for spatial tracking of heat flow as cooling occurred. Data indicate that honey bee workers collectively minimize heat gain during heating and accelerate heat loss during cooling. Thermal images show that heated areas temporarily increase in size in all directions and then rapidly decrease to safe levels (<37 °C). As such, heat shielding is reminiscent of bioheat removal via the cardiovascular system of mammals.

Modelling of heat transfer to fluids at a supercritical pressure

International Nuclear Information System (INIS)

Shuisheng, He

2014-01-01

A key feature of Supercritical Water-cooled Reactor (SCWR) is that, by raising the pressure of the reactor coolant fluid above the critical value, a phase change crisis is avoided. However, the changes in water density as it flows through the core of an SCWR are actually much higher than in the current water-cooled reactors. In a typical design, the ratio of the density of water at the core inlet to that at exit is as high as 7:1. Other fluid properties also vary significantly, especially around the pseudo-critical temperature (at which the specific heat capacity peaks). As a result, turbulent flow and heat transfer behaviour in the core is extremely complex and under certain conditions, significant heat transfer deterioration can potentially occur. Consequently, understanding and being able to predict flow and heat transfer phenomena under normal steady operation conditions and in start-up and hypothetical fault conditions are fundamental to the design of SCWR. There have been intensive studies on flow and heat transfer to fluids at supercritical pressure recently and several excellent review papers have been published. In the talk, we will focus on some turbulence modelling issues encountered in CFD simulations. The talk will first discuss some flow and heat transfer issues related to fluids at supercritical pressures and their potential implications in SCWR, and some recent developments in the understanding and modelling techniques of such problems, which will be followed by an outlook for some future developments.Factors which have a major influence on the flow and will be discussed are buoyancy and flow acceleration due to thermal expansion (both are due to density variations but involve different mechanisms) and the nonuniformity of other fluid properties. In addition, laminar-turbulent flow transition coupled with buoyancy and flow acceleration plays an important role in heat transfer effectiveness and wall temperature in the entrance region but such

Experimental study of rf pulsed heating

CERN Document Server

Laurent, L; Nantista, C; Dolgashev, V; Higashi, Y; Aicheler, M; Tantawi, S; Wuensch, W

2011-01-01

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 (R), copper silver, and silver plated co...

Electrostatic accelerators

OpenAIRE

Hinterberger, F

2006-01-01

The principle of electrostatic accelerators is presented. We consider Cockcroft– Walton, Van de Graaff and Tandem Van de Graaff accelerators. We resume high voltage generators such as cascade generators, Van de Graaff band generators, Pelletron generators, Laddertron generators and Dynamitron generators. The speci c features of accelerating tubes, ion optics and methods of voltage stabilization are described. We discuss the characteristic beam properties and the variety of possible beams. We ...

Circular Bioassay Platforms for Applications in Microwave-Accelerated Techniques.

Science.gov (United States)

Mohammed, Muzaffer; Clement, Travis C; Aslan, Kadir

2014-12-02

In this paper, we present the design of four different circular bioassay platforms, which are suitable for homogeneous microwave heating, using theoretical calculations (i.e., COMSOL™ multiphysics software). Circular bioassay platforms are constructed from poly(methyl methacrylate) (PMMA) for optical transparency between 400-800 nm, has multiple sample capacity (12, 16, 19 and 21 wells) and modified with silver nanoparticle films (SNFs) to be used in microwave-accelerated bioassays (MABs). In addition, a small monomode microwave cavity, which can be operated with an external microwave generator (100 W), for use with the bioassay platforms in MABs is also developed. Our design parameters for the circular bioassay platforms and monomode microwave cavity during microwave heating were: (i) temperature profiles, (ii) electric field distributions, (iii) location of the circular bioassay platforms inside the microwave cavity, and (iv) design and number of wells on the circular bioassay platforms. We have also carried out additional simulations to assess the use of circular bioassay platforms in a conventional kitchen microwave oven (e.g., 900 W). Our results show that the location of the circular bioassay platforms in the microwave cavity was predicted to have a significant effect on the homogeneous heating of these platforms. The 21-well circular bioassay platform design in our monomode microwave cavity was predicted to offer a homogeneous heating pattern, where inter-well temperature was observed to be in between 23.72-24.13°C and intra-well temperature difference was less than 0.21°C for 60 seconds of microwave heating, which was also verified experimentally.

A cryogenic pump with a long continuous run without filling intended for a particle accelerator

International Nuclear Information System (INIS)

Bottiglioni, F.; Coutant, J.; Fois, M.; Duthil, R.; Gelebart, J.C.; Lottin, J.C.

1977-06-01

A cryogenic pump is described, specially designed to be used in an electrostatic particle accelerator. The same tubular liquid helium bath provides pumping in the accelerating tube and around the beam. The temperature of the bath can be adjusted between 2.2 and 4.2 deg K, the liquid helium level, in the low pressure bath, is keeped constant through a feeding system made of an heat exchanger and an expansion valve. An auxiliary container for liquid nitrogen and liquid helium, at atmospheric pressure, allows a several days continuous run without filling. This system allows refilling of the container without changing the pressure on the bath [fr

Engineering design of the interaction waveguide for high-power accelerator-driven microwave free-electron lasers

International Nuclear Information System (INIS)

Hopkins, D.B.; Clay, H.W.; Stallard, B.W.; Throop, A.L.; Listvinsky, G.; Makowski, M.A.

1989-01-01

Linear induction accelerators (LIAs) operating at beam energies of a few million electron volts and currents of a few thousand amperes are suitable drivers for free-electron lasers (FELs). Such lasers are capable of producing gigawatts of peak power and megawatts of average power at microwave frequencies. Such devices are being studied as possible power sources for future high-gradient accelerators and are being constructed for plasma heating applications. At high power levels, the engineering design of the interaction waveguide presents a challenge. This paper discusses several concerns, including electrical breakdown and metal fatigue limits, choice of material, and choice of operating propagation mode. 13 refs., 3 figs

Transient analysis for lead-bismuth-cooled accelerator-driven system proposed by JAEA

International Nuclear Information System (INIS)

Sugawara, T.; Nishihara, K.; Tsujimoto, K.

2015-01-01

It is supposed that an Accelerator-driven System (ADS) is safer than conventional critical reactors since an ADS is driven by the external neutron source in the subcritical state. In this study, the transient analyses for the lead-bismuth cooled ADS proposed by JAEA were performed using the SIMMER-III and RELAP5/mod3.2 codes to investigate the possibility of core damage. In this research, 3 accidents: the protected loss of heat sink, the protected overcooling and the unprotected blockage accident were considered as typical ADS accidents. Through these calculations, it was confirmed that all calculation results, except for the protected loss of heat sink, fulfilled the no-damage criteria. In the protected loss of heat sink, the cladding tube temperature reached its melting temperature after 18-21 hours, although the calculation condition was very conservative. These results have led to requirements to design a safety system of the ADS to decrease the frequencies of accidents. (authors)

Superconducting accelerator technology

International Nuclear Information System (INIS)

Grunder, H.A.; Hartline, B.K.

1986-01-01

Modern and future accelerators for high energy and nuclear physics rely increasingly on superconducting components to achieve the required magnetic fields and accelerating fields. This paper presents a practical overview of the phenomenon of superconductivity, and describes the design issues and solutions associated with superconducting magnets and superconducting rf acceleration structures. Further development and application of superconducting components promises increased accelerator performance at reduced electric power cost

Sector ring accelerator ''RESATRON''

International Nuclear Information System (INIS)

Schwabe, E.

1980-01-01

Project of sector ring accelerator RESATRON is described. The curiosity of this accelerator is the second cycle of acceleration of the beam after stripping it on the foil. In such an accelerator heavy ions with a different ratio Z to A can be accelerated. (S.B.)

Wave propagation model of heat conduction and group speed

Science.gov (United States)

Zhang, Long; Zhang, Xiaomin; Peng, Song

2018-03-01

In view of the finite relaxation model of non-Fourier's law, the Cattaneo and Vernotte (CV) model and Fourier's law are presented in this work for comparing wave propagation modes. Independent variable translation is applied to solve the partial differential equation. Results show that the general form of the time spatial distribution of temperature for the three media comprises two solutions: those corresponding to the positive and negative logarithmic heating rates. The former shows that a group of heat waves whose spatial distribution follows the exponential function law propagates at a group speed; the speed of propagation is related to the logarithmic heating rate. The total speed of all the possible heat waves can be combined to form the group speed of the wave propagation. The latter indicates that the spatial distribution of temperature, which follows the exponential function law, decays with time. These features show that propagation accelerates when heated and decelerates when cooled. For the model media that follow Fourier's law and correspond to the positive heat rate of heat conduction, the propagation mode is also considered the propagation of a group of heat waves because the group speed has no upper bound. For the finite relaxation model with non-Fourier media, the interval of group speed is bounded and the maximum speed can be obtained when the logarithmic heating rate is exactly the reciprocal of relaxation time. And for the CV model with a non-Fourier medium, the interval of group speed is also bounded and the maximum value can be obtained when the logarithmic heating rate is infinite.

2014 Joint International Accelerator School: Beam Loss and Accelerator Protection

CERN Document Server

JAS - Joint US-CERN-Japan-Russia Accelerator School

2016-01-01

Many particle accelerators operate with very high beam power and very high energy stored in particle beams as well as in magnet systems. In the future, the beam power in high intensity accelerators will further increase. The protection of the accelerator equipment from the consequences of uncontrolled release of the energy is essential. This was the motivation for organizing a first school on beam losses and accelerator protection (in general referred to as machine protection). During the school the methods and technologies to identify, mitigate, monitor and manage the technical risks associated with the operation of accelerators with high-power beams or subsystems with large stored energy were presented. At the completion of the school the participants should have been able to understand the physical phenomena that can damage machine subsystems or interrupt operations and to analyze an accelerator facility to produce a register of technical risks and the corresponding risk mitigation and management strategie...

Status of the 1 MeV Accelerator Design for ITER NBI

Science.gov (United States)

Kuriyama, M.; Boilson, D.; Hemsworth, R.; Svensson, L.; Graceffa, J.; Schunke, B.; Decamps, H.; Tanaka, M.; Bonicelli, T.; Masiello, A.; Bigi, M.; Chitarin, G.; Luchetta, A.; Marcuzzi, D.; Pasqualotto, R.; Pomaro, N.; Serianni, G.; Sonato, P.; Toigo, V.; Zaccaria, P.; Kraus, W.; Franzen, P.; Heinemann, B.; Inoue, T.; Watanabe, K.; Kashiwagi, M.; Taniguchi, M.; Tobari, H.; De Esch, H.

2011-09-01

The beam source of neutral beam heating/current drive system for ITER is needed to accelerate the negative ion beam of 40A with D- at 1 MeV for 3600 sec. In order to realize the beam source, design and R&D works are being developed in many institutions under the coordination of ITER organization. The development of the key issues of the ion source including source plasma uniformity, suppression of co-extracted electron in D beam operation and also after the long beam duration time of over a few 100 sec, is progressed mainly in IPP with the facilities of BATMAN, MANITU and RADI. In the near future, ELISE, that will be tested the half size of the ITER ion source, will start the operation in 2011, and then SPIDER, which demonstrates negative ion production and extraction with the same size and same structure as the ITER ion source, will start the operation in 2014 as part of the NBTF. The development of the accelerator is progressed mainly in JAEA with the MeV test facility, and also the computer simulation of beam optics also developed in JAEA, CEA and RFX. The full ITER heating and current drive beam performance will be demonstrated in MITICA, which will start operation in 2016 as part of the NBTF.

Status of the 1 MeV Accelerator Design for ITER NBI

International Nuclear Information System (INIS)

Kuriyama, M.; Boilson, D.; Hemsworth, R.; Svensson, L.; Graceffa, J.; Schunke, B.; Decamps, H.; Tanaka, M.; Bonicelli, T.; Masiello, A.; Bigi, M.; Chitarin, G.; Luchetta, A.; Marcuzzi, D.; Pasqualotto, R.; Pomaro, N.; Serianni, G.; Sonato, P.; Toigo, V.; Zaccaria, P.

2011-01-01

The beam source of neutral beam heating/current drive system for ITER is needed to accelerate the negative ion beam of 40A with D - at 1 MeV for 3600 sec. In order to realize the beam source, design and R and D works are being developed in many institutions under the coordination of ITER organization. The development of the key issues of the ion source including source plasma uniformity, suppression of co-extracted electron in D beam operation and also after the long beam duration time of over a few 100 sec, is progressed mainly in IPP with the facilities of BATMAN, MANITU and RADI. In the near future, ELISE, that will be tested the half size of the ITER ion source, will start the operation in 2011, and then SPIDER, which demonstrates negative ion production and extraction with the same size and same structure as the ITER ion source, will start the operation in 2014 as part of the NBTF. The development of the accelerator is progressed mainly in JAEA with the MeV test facility, and also the computer simulation of beam optics also developed in JAEA, CEA and RFX. The full ITER heating and current drive beam performance will be demonstrated in MITICA, which will start operation in 2016 as part of the NBTF.

Linear Accelerators

International Nuclear Information System (INIS)

Vretenar, M

2014-01-01

The main features of radio-frequency linear accelerators are introduced, reviewing the different types of accelerating structures and presenting the main characteristics aspects of linac beam dynamics

Accelerator structure for a charged particle linear accelerator working in standing wave mode

International Nuclear Information System (INIS)

Tran, D.T.; Tronc, Dominique.

1977-01-01

Charged particle accelerators generally include a pre-grouping or pre-accelerating structure associated with the accelerator structure itself. But pre-grouping or pre-accelerating structures of known type (Patent application No. 70 39261 for example) present electric and dimensional characteristics that rule them out for accelerators working at high frequencies (C or X bands for example), since the distance separating the interaction spaces becomes very small in this case. The accelerator structure mentioned in this invention can be used to advantage for such accelerators [fr

Development of bipolar pulse accelerator for intense pulsed ion beam acceleration

International Nuclear Information System (INIS)

Fujioka, Y.; Mitsui, C.; Kitamura, I.; Takahashi, T.; Masugata, K.; Tanoue, H.; Arai, K.

2003-01-01

To improve the purity of an intense pulsed ion beams a new type of pulsed ion beam accelerator named 'bipolar pulse accelerator (BPA)' was proposed. In the accelerator purity of the beam is expected. To confirm the principle of the accelerator experimental system was developed. The system utilizes B y type magnetically insulated acceleration gap and operated with single polar negative pulse. A coaxial gas puff plasma gun placed in the grounded anode was used as an ion source, and source plasma (nitrogen) of current density approx. = 25 A/cm 2 , duration approx. = 1.5 μs was injected into the acceleration gap. The ions are successfully accelerated from the grounded anode to the drift tube by applying negative pulse of voltage 180 kV, duration 60 ns to the drift tube. Pulsed ion beam of current density approx. = 40 A/cm 2 , duration approx. 60 ns was obtained at 42 mm downstream from the anode surface. (author)

Heating and generation of suprathermal particles at collisionless shocks

International Nuclear Information System (INIS)

Thomsen, M.F.

1985-01-01

Collisionless plasma shocks are different from ordinary collisional fluid shocks in several important respects. They do not in general heat the electrons and ions equally, nor do they produce Maxwellian velocity distributions downstream. Furthermore, they commonly generate suprathermal particles which propagate into the upstream region, giving advance warning of the presence of the shock and providing a ''seed'' population for further acceleration to high energies. Recent space observations and theory have revealed a great deal about the heating mechanisms which occur in collisionless shocks and about the origin of the various suprathermal particle populations which are found in association with them. An overview of the present understanding of these subjects is presented herein. 83 refs., 8 figs

Experimental investigation of convection heat transfer of CO2 at supercritical pressures in a vertical circular tube at high Re

International Nuclear Information System (INIS)

Li Zhihui; Jiang Peixue

2008-01-01

Convection heat transfer during the upward flow of CO 2 at supercritical pressures in a vertical circular tube (d in = 2 mm) at high Reynolds numbers was investigated experimentally, and the effects of heat fluxes, mass fluxes, inlet temperatures, pressures, buoyancy and thermal acceleration on the convection heat transfer was analyzed. The results show that the tube wall temperature occurs abnormally distribution for high heat-fluxes with upward flow. The degree of deteriorated heat transfer increases with increasing heat flux. Increasing of the mass flux delays the occurrence of the deterioration of heat transfer and weakens the deterioration of heat transfer down-stream section. The inlet temperature strongly influences the heat transfer. The deterioration degree of heat transfer decreases with increasing pressure. (authors)

Collisionless shock formation and the prompt acceleration of solar flare ions

Science.gov (United States)

Cargill, P. J.; Goodrich, C. C.; Vlahos, L.

1988-01-01

The formation mechanisms of collisionless shocks in solar flare plasmas are investigated. The priamry flare energy release is assumed to arise in the coronal portion of a flare loop as many small regions or 'hot spots' where the plasma beta locally exceeds unity. One dimensional hybrid numerical simulations show that the expansion of these 'hot spots' in a direction either perpendicular or oblique to the ambient magnetic field gives rise to collisionless shocks in a few Omega(i), where Omega(i) is the local ion cyclotron frequency. For solar parameters, this is less than 1 second. The local shocks are then subsequently able to accelerate particles to 10 MeV in less than 1 second by a combined drift-diffusive process. The formation mechanism may also give rise to energetic ions of 100 keV in the shock vicinity. The presence of these energetic ions is due either to ion heating or ion beam instabilities and they may act as a seed population for further acceleration. The prompt acceleration of ions inferred from the Gamma Ray Spectrometer on the Solar Maximum Mission can thus be explained by this mechanism.

KEK digital accelerator

Directory of Open Access Journals (Sweden)

T. Iwashita

2011-07-01

Full Text Available The High Energy Accelerator Research Organization KEK digital accelerator (KEK-DA is a renovation of the KEK 500 MeV booster proton synchrotron, which was shut down in 2006. The existing 40 MeV drift tube linac and rf cavities have been replaced by an electron cyclotron resonance (ECR ion source embedded in a 200 kV high-voltage terminal and induction acceleration cells, respectively. A DA is, in principle, capable of accelerating any species of ion in all possible charge states. The KEK-DA is characterized by specific accelerator components such as a permanent magnet X-band ECR ion source, a low-energy transport line, an electrostatic injection kicker, an extraction septum magnet operated in air, combined-function main magnets, and an induction acceleration system. The induction acceleration method, integrating modern pulse power technology and state-of-art digital control, is crucial for the rapid-cycle KEK-DA. The key issues of beam dynamics associated with low-energy injection of heavy ions are beam loss caused by electron capture and stripping as results of the interaction with residual gas molecules and the closed orbit distortion resulting from relatively high remanent fields in the bending magnets. Attractive applications of this accelerator in materials and biological sciences are discussed.