Stationary Population Inversion in an Expanding Argon Plasma Jet by Helium Puffing

International Nuclear Information System (INIS)

Akatsuka, H.; Kano, K.

2005-01-01

An experiment of He gas-contact for generating population inversion in a recombining Ar plasma jet is carried out. Population inversion between Ar I excited states 5s' → 4p'[1/2]1 and 5s' → 4p[3/2]1,2, [5/2]2,3 is created by helium gas-contact cooling of electrons, whereas it is not created without gas-contact. Ar I lines 1.14 μm, 1.34 μm, and 1.09 μm are strongly enhanced due to the He gas cooling. It is experimentally found that helium gas contact effectively lowers electron temperature of the Ar plasma jet. The mechanisms giving rise to population inversion are discussed in terms of atomic collisional processes of the recombining plasma. The experimental results of electron temperature and population densities are discussed by simple numerical analysis which we previously developed. It is shown that the experimental results are well explained by our modeling quantitatively for the case without gas contact, except that the agreement of number densities of lower lying non-LTE levels is qualitative for the case with the gas contact

Numerical modeling and validation of helium jet impingement cooling of high heat flux divertor components

International Nuclear Information System (INIS)

Koncar, Bostjan; Simonovski, Igor; Norajitra, Prachai

2009-01-01

Numerical analyses of jet impingement cooling presented in this paper were performed as a part of helium-cooled divertor studies for post-ITER generation of fusion reactors. The cooling ability of divertor cooled by multiple helium jets was analysed. Thermal-hydraulic characteristics and temperature distributions in the solid structures were predicted for the reference geometry of one cooling finger. To assess numerical errors, different meshes (hexagonal, tetra, tetra-prism) and discretisation schemes were used. The temperatures in the solid structures decrease with finer mesh and higher order discretisation and converge towards finite values. Numerical simulations were validated against high heat flux experiments, performed at Efremov Institute, St. Petersburg. The predicted design parameters show reasonable agreement with measured data. The calculated maximum thimble temperature was below the tile-thimble brazing temperature, indicating good heat removal capability of reference divertor design. (author)

Three electrode atmospheric pressure plasma jet in helium flow

Science.gov (United States)

Maletic, Dejan; Puac, Nevena; Malovic, Gordana; Petrovic, Zoran Lj.

2015-09-01

Plasma jets are widely used in various types of applications and lately more and more in the field of plasma medicine. However, it is not only their applicability that distinguishes them from other atmospheric plasma sources, but also the behavior of the plasma. It was shown that plasma plume is not continuous, but discrete set of plasma packages. Here we present iCCD images and current voltage characteristics of a three electrode plasma jet. Our plasma jet has a simple design with body made of glass tube and two transparent electrodes wrapped around it. The additional third metal tip electrode was positioned at 10 and 25 mm in front of the jet nozzle and connected to the same potential as the powered electrode. Power transmitted to the plasma was from 0.5 W to 4.0 W and the helium flow rate was kept constant at 4 slm. For the 10 mm configuration plasma is ignited on the metal tip in the whole period of the excitation signal and in the positive half cycle plasma ``bullet'' is propagating beyond the metal tip. In contrast to that, for the 25 mm configuration at the tip electrode plasma can be seen only in the minimum and maximum of the excitation signal, and there is no plasma ``bullet'' formation. This research has been supported by the Ministry of Education, Science and Technological Development, Republic of Serbia, under projects ON171037 and III41011.

The Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target

International Nuclear Information System (INIS)

Chipps, K.A.; Greife, U.; Bardayan, D.W.; Blackmon, J.C.; Kontos, A.; Linhardt, L.E.; Matos, M.; Pain, S.D.; Pittman, S.T.; Sachs, A.; Schatz, H.; Schmitt, K.T.; Smith, M.S.; Thompson, P.

2014-01-01

New radioactive ion beam (RIB) facilities will push further away from stability and enable the next generation of nuclear physics experiments. Of great importance to the future of RIB physics are scattering, transfer, and capture reaction measurements of rare, exotic, and unstable nuclei on light targets such as hydrogen and helium. These measurements require targets that are dense, highly localized, and pure. Targets must also accommodate the use of large area silicon detector arrays, high-efficiency gamma arrays, and heavy ion detector systems to efficiently measure the reaction products. To address these issues, the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) Collaboration has designed, built, and characterized a supersonic gas jet target, capable of providing gas areal densities on par with commonly used solid targets within a region of a few millimeters diameter. Densities of over 5×10 18 atoms/cm 2 of helium have been achieved, making the JENSA gas jet target the most dense helium jet achieved so far

Efficiency of an on-line isotope separator system employing cooled and NaCl-loaded He-jet methods

International Nuclear Information System (INIS)

Aeystoe, J.; Rantala, V.; Valli, K.; Hillebrand, S.; Kortelahti, M.; Eskola, K.; Raunemaa, T.

1976-01-01

A pure helium-jet at liquid nitrogen temperature coupled to a Nielsen type ion source, and a NaCl-loaded helium-jet coupled to a hollow-cathode ion source have been investigated as means to connect a cyclotron target chamber on-line to a mass separator. Technical details and performances of some critical parts of the system are described. Total separation efficiencies measured under various experimental conditions for several nuclides vary between 0.01 and 1.0%. (Auth.)

Development of methods of transport of nuclear reaction products by helium jet, in connection with the ALICE accelerator

International Nuclear Information System (INIS)

Deprun, C.; Gauvin, H.; Le Beyec, Y.

1976-01-01

The He-jet transport systems for use with the heavy-ion accelerator ALICE at Orsay are described in detail. The dependence of the gas flow rate on various parameters (pressure, length and diameter of the capillary) was investigated. Off-line measurements were carried out with a 252 Cf source. Effect on collection yield of UV radiation and additives to the helium was checked. The influence of the distance between the target and the capillary on the collection efficiency for short-lived isotopes of Yb was investigated. Some other useful details are also discussed (collector, volume of the reaction chamber, etc.). Various applications of the He-jet method are described: particle identification, angular distribution of reaction products, mass identification of radioactive nuclei. (Auth.)

Plasmid DNA damage induced by helium atmospheric pressure plasma jet

Science.gov (United States)

Han, Xu; Cantrell, William A.; Escobar, Erika E.; Ptasinska, Sylwia

2014-03-01

A helium atmospheric pressure plasma jet (APPJ) is applied to induce damage to aqueous plasmid DNA. The resulting fractions of the DNA conformers, which indicate intact molecules or DNA with single- or double-strand breaks, are determined using agarose gel electrophoresis. The DNA strand breaks increase with a decrease in the distance between the APPJ and DNA samples under two working conditions of the plasma source with different parameters of applied electric pulses. The damage level induced in the plasmid DNA is also enhanced with increased plasma irradiation time. The reactive species generated in the APPJ are characterized by optical emission spectra, and their roles in possible DNA damage processes occurring in an aqueous environment are also discussed.

The installation of helium auxiliary systems in HTGR

International Nuclear Information System (INIS)

Qin Zhenya; Fu Xiaodong

1993-01-01

The inert gas Helium was chosen as reactor coolant in high temperature gas coolant reactor, therefore a set of Special and uncomplex helium auxiliary systems will be installed, the safe operation of HTR-10 can be safeguarded. It does not effect the inherent safety of HTR-10 MW if any one of all those systems were damaged during operation condition. This article introduces the design function and the system principle of all helium auxiliary systems to be installed in HTR-10. Those systems include: helium purification and its regeneration system, helium supply and storage system, pressure control and release system of primary system, dump system for helium auxiliary system and fuel handling, gaseous waste storage system, water extraction system for helium auxiliary systems and evacuation system for primary system

Development of gas-jet transport systems for fission products and coupling these with methods for continuous separation of short-lived product nuclides

International Nuclear Information System (INIS)

Stender, E.

1979-01-01

The development of gas-jet transport systems for fission products as well as the coupling of these with continuous separation methods from aqueous solutions (SISAK) and with a mass separator for on-line separation of neutron-rich nuclides are described in this work. Nuclides from the fission of 235 U or other fission materials can be transported using gas-jet systems with thermal neutrons over larger distances (100 m and over). Aerosols (clusters) of either organic (e.g. ethylene) or inorganic nature (e.g. potassium chloride) serve as carrier for the nuclides. The clusters are passed through 1 mm capillaries with a transport gas (nitrogen, helium etc.) under laminar flow conditions. The diameter of the cluster fluctuates between 10 -7 and 10 -6 m. The time required from the production of a nuclide to its detection at the end of a 8 m long capillary tube is 0.8 s for the ethylene/nitrogen and potassium chloride/helium gas-jet systems. By coupling various gas-jet systems with the continuous extraction technique SISAK working with H centrifuges, the elements lanthanum, cerium, praseodymium, zirconium, niobium and technetium can be separated out of the complex fission product mixtures. The on-line technetium chemistry was used with neutron-rich 106 Tc (36 s), 107 Tc (21 s) and 108 Tc (5 s) for γγ(t) measurements. The coupling of a potassium chloride/helium gas jet with a mass separator equiped with a plasma ion source is described. The dependence of the transmission rate of various test parameters is investigated to optimize the system. (orig.) [de

DC-driven plasma gun: self-oscillatory operation mode of atmospheric-pressure helium plasma jet comprised of repetitive streamer breakdowns

Science.gov (United States)

Wang, Xingxing; Shashurin, Alexey

2017-02-01

This paper presents and studies helium atmospheric pressure plasma jet comprised of a series of repetitive streamer breakdowns, which is driven by pure DC high voltage (self-oscillatory behavior). The repetition frequency of the breakdowns is governed by the geometry of discharge electrodes/surroundings and gas flow rate. Each next streamer is initiated when the electric field on the anode tip recovers after the previous breakdown and reaches the breakdown threshold value of about 2.5 kV cm-1. One type of the helium plasma gun designed using this operational principle is demonstrated. The gun operates on about 3 kV DC high voltage and is comprised of the series of the repetitive streamer breakdowns at a frequency of about 13 kHz.

A new helium gas recovery and purification system

International Nuclear Information System (INIS)

Yamamotot, T.; Suzuki, H.; Ishii, J.; Hamana, I.; Hayashi, S.; Mizutani, S.; Sanjo, S.

1974-01-01

A helium gas recovery and purification system, based on the principle of gas permeation through a membrane, is described. The system can be used for the purification of helium gas containing air as a contaminant. The apparatus, operating at ambient temperature does not need constant attention, the recovery ratio of helium gas is satisfactory and running costs are low. Gases other than helium can be processed with the apparatus. (U.K.)

Bed system performance in helium circulation mode

Energy Technology Data Exchange (ETDEWEB)

Kim, Yean Jin; Jung, Kwang Jin; Ahn, Do Hee; Chung, Hong Suk [UST, Daejeon (Korea, Republic of); Kang, Hee Suk [KAERI, Daejeon (Korea, Republic of); Yun, Sei Hun [NFRI, Deajeon (Korea, Republic of)

2016-05-15

As a part of the International Thermonuclear Experimental Reactor (ITER) Project, We have conducted an experiment for storing hydrogen to depleted uranium and zirconium cobalt. The helium blanket effect has been observed in experiments using metal hydrides. The collapse of the hydrogen isotopes are accompanied by the decay heat and helium-3. Helium-3 dramatically reduces the hydrogen isotope storage capacity by surrounding the metal. This phenomenon is called a helium blanket effect. In addition the authors are working on the recovery and removal techniques of helium-3. In this paper, we discuss the equipment used to test the helium blanket effect and the results of a helium circulation experiment. The helium-3 produced surrounds the storage material surface and thus disturbs the reaction of the storage material and the hydrogen isotope. Even if the amount of helium-3 is small, the storage capacity of the SDS bed significantly drops. This phenomenon is the helium blanket effect. To resolve this phenomenon, a circulating loop was introduced. Using a circulating system, helium can be separated from the storage material. We made a helium loop that includes a ZrCo bed. Then using a metal bellows pump, we tested the helium circulation.

Preliminary Overview of a Helium Cooling System for the Secondary Helium Loop in VHTR-based SI Hydrogen Production Facilities

Energy Technology Data Exchange (ETDEWEB)

Shin, Youngjoon; Cho, Mintaek; Kim, Dahee; Lee, Taehoon; Lee, Kiyoung; Kim, Yongwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

Nuclear hydrogen production facilities consist of a very high temperature gas-cooled nuclear reactor (VHTR) system, intermediate heat exchanger (IHX) system, and a sulfur-iodine (SI) thermochemical process. This study focuses on the coupling system between the IHX system and SI thermochemical process. To prevent the propagation of the thermal disturbance owing to the abnormal operation of the SI process components from the IHX system to the VHTR system, a helium cooling system for the secondary helium of the IHX is required. In this paper, the helium cooling system has been studied. The temperature fluctuation of the secondary helium owing to the abnormal operation of the SI process was then calculated based on the proposed coupling system model. Finally, the preliminary conceptual design of the helium cooling system with a steam generator and forced-draft air-cooled heat exchanger to mitigate the thermal disturbance has been carried out. A conceptual flow diagram of a helium cooling system between the IHX and SI thermochemical processes in VHTR-based SI hydrogen production facilities has been proposed. A helium cooling system for the secondary helium of the IHX in this flow diagram prevents the propagation of the thermal disturbance from the IHX system to the VHTR system, owing to the abnormal operation of the SI process components. As a result of a dynamic simulation to anticipate the fluctuations of the secondary helium temperature owing to the abnormal operation of the SI process components with a hydrogen production rate of 60 mol·H{sub 2}/s, it is recommended that the maximum helium cooling capacity to recover the normal operation temperature of 450 .deg. C is 31,933.4 kJ/s. To satisfy this helium cooling capacity, a U-type steam generator, which has a heat transfer area of 12 m{sup 2}, and a forced-draft air-cooled condenser, which has a heat transfer area of 12,388.67 m{sup 2}, are required for the secondary helium cooling system.

Deuterium to helium plasma-wall change-over experiments in the JET MkII-gas box divertor

International Nuclear Information System (INIS)

Hillis, D.L.; Loarer, T.; Bucalossi, J.; Pospieszczyk, A.; Fundamenski, W.; Matthews, G.; Meigs, A.; Morgan, P.; Phillips, V.; Pitts, R.; Stamp, M.; Hellermann, M. von

2003-01-01

The deuterium and helium dynamics in the plasma and subdivertor regions of JET are compared during a sequence of similar ohmic and ICRH pulses where 100% He gas is injected into the JET vacuum vessel, whose graphite walls were previously saturated with deuterium. After the first six He fueled change-over discharges, only He plasma operation was performed. Following this investigation, the situation is reversed and the change-over from an initially saturated He wall is investigated when only D 2 plasma fuelling is used. The He concentration is measured in the subdivertor with a species selective Penning gauge. Comparison of the time dependence of the divertor concentrations with those at the edge and strike point shows significant differences during the first six discharges. This difference along with a global He particle balance is used to assess the status of the wall saturation over the initial 6-7 He change-over discharges

KSTAR Helium Refrigeration System Design and Manufacturing

International Nuclear Information System (INIS)

Dauguet, P.; Briend, P.; Abe, I.; Fauve, E.; Bernhardt, J.-M.; Andrieu, F.; Beauvisage, J.

2006-01-01

The tokamak developed in the KSTAR (Korean Superconducting Tokamak Advanced Research) project makes intensive use of superconducting magnets operated at 4.5 K. The cold components of the KSTAR tokamak require forced flow of supercritical helium for magnets/structure, boiling liquid helium for current leads, and gaseous helium for thermal shields. The cryogenic system will provide stable operation and full automatic control. A three-pressure helium cycle composed of six turbines has been customised design for this project. The '' design '' operating mode results with a system composed of a 9 kW refrigerator (including safety margin) and using gas and liquid storages for mass balancing. During Shot/Standby mode, the heat loads are highly time-dependent. A thermal damper is used to smooth these variations and will allow stable operation. (author)

A numerical study of shock-acceleration of a diffuse helium cylinder

International Nuclear Information System (INIS)

Greenough, J.A.; Bell, J.; Colella, P.

1995-08-01

The development of a shock-accelerated diffuse Helium cylindrical inhomogeneity is investigated using a new numerical method. The new algorithm is a higher-order Godunov implementation of the so-called multi-fluid equations. This system correctly models multiple component mixtures by accounting for differential compressibility effects. This base integrator is embedded in an implementation of adaptive mesh refinement (AMR) that allows efficient increase in resolution where the computational effort is concentrated where high accuracy, or increased resolution, are required. Qualitative and quantitative comparison with previous experimental data is excellent. The simulations show that counter-sign vortex blobs are deposited in the jet core by baroclinic generation of the curved shock wave as it traverses the jet. This vorticity deposition occurs over timescales that scale with the shock passage time (∼ 10μsec). Three phases of development are identified and characterized. The first is the weak deformation (WD) phase, where there is weak distortion of the Helium jet due to weak vorticity induced velocity effects. The second phase is the strong deformation (SD) phase where there is large distortion for the jet and the vortex blobs due to large induced velocity effects. The last is a relaxation/reorganization (RR) phase where the vorticity field reorganizes into point-like vortex pair

One- and zero-dimensional electron systems over liquid helium (Review article)

CERN Document Server

Kovdrya, Y Z

2003-01-01

Experimental and theoretical investigations of one-dimensional and zero-dimensional electron systems near the liquid helium surface are surveyed. The properties of electron states over the plane surface of liquid helium including thin layers of helium are considered. The methods of realization of one- and zero-dimensional electron systems are discussed, and the results of experimental and theoretical investigations of their properties are given. The experiments with localization processes in a quasi-one-dimensional electron systems on liquid helium are described. The collective effects in one-dimensional and quasi-one-dimensional electron systems are considered, and the point of possible application of low-dimensional electron systems on liquid helium in electron devices and quantum computers is discussed.

Installation and Commissioning of the Helium Refrigeration System for the HANARO-CNS

International Nuclear Information System (INIS)

Choi, Jung Woon; Kim, Young Ki; Wu, Sang Ik; Son, Woo Jung

2009-11-01

The cold neutron source (CNS), which will be installed in the vertical CN hole of the reflector tank at HANARO, makes thermal neutrons to moderate into the cold neutrons with the ranges of 0.1 ∼ 10 meV passing through a moderator at about 22K. A moderator to produce cold neutrons is liquid hydrogen, which liquefies by the heat transfer with cryogenic helium flowing from the helium refrigeration system. For the maintenance of liquid hydrogen in the IPA, the CNS system is mainly consisted of the hydrogen system to supply the hydrogen to the IPA, the vacuum system to keep the cryogenic liquid hydrogen in the IPA, and the helium refrigeration system to liquefy the hydrogen gas. The helium refrigeration system can be divided into two sections: one is the helium compression part from the low pressure gas to the high pressure gas and the other is the helium expansion part from the high temperature gas and pressure to low temperature and pressure gas by the expansion turbine. The helium refrigeration system except the warm helium pipe and the helium buffer tank has been manufactured by Linde Kryotechnik, AG in Switzerland and installed in the research reactor hall, HANARO. Other components have been manufactured in the domestic company. This technical report deals with the issues, its solutions, and other particular points while the helium refrigeration system was installed at site, verified its performance, and conducted its commissioning along the reactor operation. Furthermore, the operation procedure of the helium refrigeration system is included in here for the normal operation of the CNS

A comparison between characteristics of atmospheric-pressure plasma jets sustained by nanosecond- and microsecond-pulse generators in helium

International Nuclear Information System (INIS)

Zhang, Cheng; Shao, Tao; Wang, Ruixue; Yan, Ping; Zhou, Zhongsheng; Zhou, Yixiao

2014-01-01

Power source is an important parameter that can affect the characteristics of atmospheric-pressure plasma jets (APPJs), because it can play a key role on the discharge characteristics and ionization process of APPJs. In this paper, the characteristics of helium APPJs sustained by both nanosecond-pulse and microsecond-pulse generators are compared from the aspects of plume length, discharge current, consumption power, energy, and optical emission spectrum. Experimental results showed that the pulsed APPJ was initiated near the high-voltage electrode with a small curvature radius, and then the stable helium APPJ could be observed when the applied voltage increased. Moreover, the discharge current of the nanosecond-pulse APPJ was larger than that of the microsecond-pulse APPJ. Furthermore, although the nanosecond-pulse generator consumed less energy than the microsecond-pulse generator, longer plume length, larger instantaneous power per pulse and stronger spectral line intensity could be obtained in the nanosecond-pulse excitation case. In addition, some discussion indicated that the rise time of the applied voltage could play a prominent role on the generation of APPJs

Development of 18 K helium refrigeration system for CERN

CERN Document Server

CERN. Geneva

2004-01-01

The Conseil Europeen pour Ia Recherche Nucleaire (CERN) placed an order for a 1.8 K helium refrigeration system with IHI for the Large Hadron Collider project in 1999. IHI formed a consortium with Linde Kryotechnik AG (Switzerland), which has long experience with helium refrigeration systems. IHI designed and manufactured cold compressors based on leading technologies and expertise for turbo machinery. The cold compressor has the highest efficiency in the world. This paper describes the 1.8 K helium refrigeration system and performance test results at CERN. (5 refs).

Experimental Validation of the LHC Helium Relief System Flow Modeling

CERN Document Server

Fydrych, J; Riddone, G

2006-01-01

In case of simultaneous resistive transitions in a whole sector of magnets in the Large Hadron Collider, the helium would be vented from the cold masses to a dedicated recovery system. During the discharge the cold helium will eventually enter a pipe at room temperature. During the first period of the flow the helium will be heated intensely due to the pipe heat capacity. To study the changes of the helium thermodynamic and flow parameters we have simulated numerically the most critical flow cases. To verify and validate numerical results, a dedicated laboratory test rig representing the helium relief system has been designed and commissioned. Both numerical and experimental results allow us to determine the distributions of the helium parameters along the pipes as well as mechanical strains and stresses.

A quantitative experiment on the fountain effect in superfluid helium

Science.gov (United States)

Amigó, M. L.; Herrera, T.; Neñer, L.; Peralta Gavensky, L.; Turco, F.; Luzuriaga, J.

2017-09-01

Superfluid helium, a state of matter existing at low temperatures, shows many remarkable properties. One example is the so called fountain effect, where a heater can produce a jet of helium. This converts heat into mechanical motion; a machine with no moving parts, but working only below 2 K. Allen and Jones first demonstrated the effect in 1938, but their work was basically qualitative. We now present data of a quantitative version of the experiment. We have measured the heat supplied, the temperature and the height of the jet produced. We also develop equations, based on the two-fluid model of superfluid helium, that give a satisfactory fit to the data. The experiment has been performed by advanced undergraduate students in our home institution, and illustrates in a vivid way some of the striking properties of the superfluid state.

Helium refrigeration system for hydrogen liquefaction applications

Science.gov (United States)

Nair, J. Kumar, Sr.; Menon, RS; Goyal, M.; Ansari, NA; Chakravarty, A.; Joemon, V.

2017-02-01

Liquid hydrogen around 20 K is used as cold moderator for generating “cold neutron beam” in nuclear research reactors. A cryogenic helium refrigeration system is the core upon which such hydrogen liquefaction applications are built. A thermodynamic process based on reversed Brayton cycle with two stage expansion using high speed cryogenic turboexpanders (TEX) along with a pair of compact high effectiveness process heat exchangers (HX), is well suited for such applications. An existing helium refrigeration system, which had earlier demonstrated a refrigeration capacity of 470 W at around 20 K, is modified based on past operational experiences and newer application requirements. Modifications include addition of a new heat exchanger to simulate cryogenic process load and two other heat exchangers for controlling the temperatures of helium streams leading out to the application system. To incorporate these changes, cryogenic piping inside the cold box is suitably modified. This paper presents process simulation, sizing of new heat exchangers as well as fabrication aspects of the modified cryogenic process piping.

Measurement of air entrainment in plasma jets

International Nuclear Information System (INIS)

Fincke, J.R.; Rodriquez, R.; Pentecost, C.G.

1990-01-01

The concentration and temperature of air entrained into argon and helium plasma jets has been measured using coherent anti-Stokes Raman spectroscopy (CARS). The argon plasma flow field is characterized by a short region of well behaved laminar flow near the nozzle exit followed by an abrupt transition to turbulence. Once the transition of turbulence occurs, air is rapidly mixed into the jet core. The location of the transition region is determined by the rapid cooling of the jet and the resulting increase in Reynolds number. In contrast, the helium plasma flow field never exceeds a Reynolds number of 200 and remains laminar. The entrainment process in this case is controlled by molecular diffusion rather than turbulent mixing. 9 refs., 5 figs., 1 tab

A multimaterial electrohydrodynamic jet (E-jet) printing system

International Nuclear Information System (INIS)

Sutanto, E; Shigeta, K; Kim, Y K; Graf, P G; Hoelzle, D J; Barton, K L; Alleyne, A G; Ferreira, P M; Rogers, J A

2012-01-01

Electrohydrodynamic jet (E-jet) printing has emerged as a high-resolution alternative to other forms of direct solution-based fabrication approaches, such as ink-jet printing. This paper discusses the design, integration and operation of a unique E-jet printing platform. The uniqueness lies in the ability to utilize multiple materials in the same overall print-head, thereby enabling increased degrees of heterogeneous integration of different functionalities on a single substrate. By utilizing multiple individual print-heads, with a carrousel indexing among them, increased material flexibility is achieved. The hardware design and system operation for a relatively inexpensive system are developed and presented. Crossover interconnects and multiple fluorescent tagged proteins, demonstrating printed electronics and biological sensing applications, respectively. (paper)

Screw compressor system for industrial-scale helium refrigerators or industrial ammonia screw compressors for helium refrigeration systems; Schraubenkompressor-System fuer Helium-Grosskaelteanlage oder Ammoniak-Schraubenverdichter aus Industrieanwendungen fuer Helium-Kaelteanlagen

Energy Technology Data Exchange (ETDEWEB)

Fredrich, O.; Mosemann, D.; Zaytsev, D. [GEA Grasso GmbH Refrigeration Technology, Berlin (Germany)

2007-07-01

Material characteristics, requirements and measured data of ammonia and helium compression are compared. The compressor lines for industrial ammonia and helium refrigerators are presented, and important characteristics of the compressors are explained. The test stand for performance measurements with helium and ammonia is described, and results are presented. In spite of the different characteristics of the fluids, the compressor-specific efficiencies (supply characteristic, quality characteristic) were found to be largely identical. The values calculated for helium on the basis of NH3 test runs were found to be realistic, which means that the decades of experience with ammonia in industrial applications can be applied to helium compression as well. The design of screw compressor aggregates (skids) in industrial refrigeration is discussed and illustrated by examples. (orig.)

Investigation of impurity-helium solid phase decomposition

International Nuclear Information System (INIS)

Boltnev, R.E.; Gordon, E.B.; Krushinskaya, I.N.; Martynenko, M.V.; Pel'menev, A.A.; Popov, E.A.; Khmelenko, V.V.; Shestakov, A.F.

1997-01-01

The element composition of the impurity-helium solid phase (IHSP), grown by injecting helium gas jet, involving Ne, Ar, Kr, and Xe atoms and N 2 molecules, into superfluid helium, has been studied. The measured stoichiometric ratios, S = N H e / N I m, are well over the values expected from the model of frozen together monolayer helium clusters. The theoretical possibility for the freezing of two layers helium clusters is justified in the context of the model of IHSP helium subsystem, filled the space between rigid impurity centers. The process of decomposition of impurity-helium (IH)-samples taken out of liquid helium in the temperature range 1,5 - 12 K and the pressure range 10-500 Torr has been studied. It is found that there are two stages of samples decomposition: a slow stage characterized by sample self cooling and a fast one accompanied by heat release. These results suggest, that the IHSP consists of two types of helium - weakly bound and strongly bound helium - that can be assigned to the second and the first coordination helium spheres, respectively, formed around heavy impurity particles. A tendency for enhancement of IHSP thermo stability with increasing the impurity mass is observed. Increase of helium vapor pressure above the sample causes the improvement of IH sample stability. Upon destruction of IH samples, containing nitrogen atoms, a thermoluminescence induced by atom recombination has been detected in the temperature region 3-4,5 K. This suggests that numerous chemical reactions may be realized in solidified helium

Investigation of Jet Noise Using Optical Holography

Science.gov (United States)

1973-04-01

Holographic interferograms have been made of cold, laboratory scale, supersonic air and nitrogen jet in the mach number range of 2.1 ot 3.4, and of helium jets in the mach number range of 1.5 to 2.95. These holograms demonstrate that the acoustic fie...

Supersonic jets of hydrogen and helium for laser wakefield acceleration

CERN Document Server

Svensson, K.; Wojda, F.; Senje, L.; Burza, M.; Aurand, B.; Genoud, G.; Persson, A.; Wahlström, C.-G.; Lundh, O.

2016-01-01

The properties of laser wakefield accelerated electrons in supersonic gas flows of hydrogen and helium are investigated. At identical backing pressure, we find that electron beams emerging from helium show large variations in their spectral and spatial distributions, whereas electron beams accelerated in hydrogen plasmas show a higher degree of reproducibility. In an experimental investigation of the relation between neutral gas density and backing pressure, it is found that the resulting number density for helium is ∼30% higher than for hydrogen at the same backing pressure. The observed differences in electron beam properties between the two gases can thus be explained by differences in plasma electron density. This interpretation is verified by repeating the laser wakefield acceleration experiment using similar plasma electron densities for the two gases, which then yielded electron beams with similar properties.

Supersonic jets of hydrogen and helium for laser wakefield acceleration

Directory of Open Access Journals (Sweden)

K. Svensson

2016-05-01

Full Text Available The properties of laser wakefield accelerated electrons in supersonic gas flows of hydrogen and helium are investigated. At identical backing pressure, we find that electron beams emerging from helium show large variations in their spectral and spatial distributions, whereas electron beams accelerated in hydrogen plasmas show a higher degree of reproducibility. In an experimental investigation of the relation between neutral gas density and backing pressure, it is found that the resulting number density for helium is ∼30% higher than for hydrogen at the same backing pressure. The observed differences in electron beam properties between the two gases can thus be explained by differences in plasma electron density. This interpretation is verified by repeating the laser wakefield acceleration experiment using similar plasma electron densities for the two gases, which then yielded electron beams with similar properties.

Velocity slip of gas mixtures in free jet expansions

International Nuclear Information System (INIS)

Cattolica, R.J.; Talbot, L.; Coe, D.

1976-11-01

Velocity slip in gas mixtures of argon and helium in axisymmetric free jet expansions has been measured using a grating monochromator together with a computer-controlled Fabry-Perot interferometer to observe the fluorescence excited by an electron beam. The Doppler shift between the fluorescence observed parallel and perpendicular to the centerline of the free jet was used to measure the mean velocity of a particular species along the jet centerline, employing the 4880 A line for argon and the 5016 A line for helium. By alternately tracking the parallel and perpendicular fluorescence, the Doppler shift due to the mean velocity was measured directly with an accuracy of 1 percent. Flow field surveys have been made in the initial acceleration region where the flow becomes hypersonic and in the far field region. The differences between argon and helium mean velocities (velocity slip) are in good agreement with molecular beam data and show a correlation with an inverse Knudsen number

Helium-Hydrogen Recovery System, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Immense quantities of expensive liquefied helium are required at Stennis and Kennedy Space Centers for pre-cooling rocket engine propellant systems prior to filling...

Acquisition system testing with superfluid helium

International Nuclear Information System (INIS)

Anderson, J.E.; Fester, D.A.; DiPirro, M.J.

1988-01-01

NASA is evaluating both a thermomechanical pump and centrifugal pump for the SHOOT experiment using capillary fluid acquisition systems. Tests were conducted for these systems with superfluid helium under adverse operating conditions. Minus one-g outflow tests were run in conjunction with the thermomechanical pump. Both fine mesh screen and porous sponges were tested. A screen acquisition device was also tested with the low-NPSH centrifugal pump. Results to date show that the screen and sponge are capable of supplying superfluid helium to the thermomechanical pump inlet against a one-g head up to four cm. This is more than sufficient for the SHOOT application. Results with the sponge were reproducible while those with the screen could not always be repeated

A numerical study of shock-acceleration of a diffuse helium cylinder. Revision 1

International Nuclear Information System (INIS)

Greenough, J.A.; Jacobs, J.W.

1995-08-01

The development of a shock-accelerated diffuse Helium cylindrical inhomogeneity is investigated using a new numerical method. The new algorithm is a higher-order Godunov implementation of the so-called multi-fluid equations. This system correctly models multiple component mixtures by accounting for differential compressibility effects. This base integrator is embedded in an implementation of adaptive mesh refinement (AMR) that allows efficient increase in resolution by concentrating the computational effort where high accuracy, or increased resolution, are required. Qualitative and quantitative comparison with previous experimental data is excellent. The simulations show that counter-sign vortex blobs are deposited in the jet core by baroclinic generation of the curved shock wave as it traverses the jet. This vorticity deposition occurs over timescales that scale with the shock passage time (∼ 10microsec). Three phases of development are identified and characterized. The first is the weak deformation (WD) phase, where there is weak distortion of the Helium jet due to weak vorticity induced velocity effects. The second phase is the strong deformation (SD) phase where there is large distortion for the jet and the vortex blobs due to large induced velocity effects. The last is a relaxation/reorganization (RR) phase where the vorticity field is reorganized into point-like vortex pair. This class of problem has applications in such disparate fields as inertial confinement fusion (ICF) and high-speed combustion

Helium refrigerator-liquefier system for MHD generator

International Nuclear Information System (INIS)

Akiyama, Y.; Ishii, H.; Mori, Y.; Yamamoto, M.; Wada, R.; Ando, M.

1974-01-01

MHD power generators have been investigated in the Electro-Technical Laboratory as one of the National Research and Development Programmes. A helium refrigerator-liquefier system has been developed to cool the superconducting magnet for a 1000 kW class MHD power generator. The turboexpander with low temperature gas bearings and an alternator had been developed for the MHD project at the Electro-Technical Laboratory previously. The liquefaction capacity is 250 iota/h and the refrigeration power is 2.9 kW at 20 K. The superconducting magnet is 50 tons and the cryostat has a liquid helium volume of 2700 iota. The evaporation rate is 60 to 80 iota/h. It takes, in all 2 to 3 weeks to fill the cryostat with liquid helium. (author)

Gas Mixtures for Welding with Micro-Jet Cooling

OpenAIRE

Węgrzyn T.

2015-01-01

Welding with micro-jet cooling after was tested only for MIG and MAG processes. For micro-jet gases was tested only argon, helium and nitrogen. A paper presents a piece of information about gas mixtures for micro-jet cooling after in welding. There are put down information about gas mixtures that could be chosen both for MAG welding and for micro-jet process. There were given main information about influence of various micro-jet gas mixtures on metallographic structure of steel welds. Mechani...

Helium refrigeration system for BNL colliding beam accelerator

International Nuclear Information System (INIS)

Brown, D.P.; Farah, Y.; Gibbs, R.J.; Schlafke, A.P.; Schneider, W.J.; Sondericker, J.H.; Wu, K.C.

1983-01-01

A Helium Refrigeration System which will supply the cooling required for the Colliding Beam Accelerator at Brookhaven National Laboratory is under construction. Testing of the compressor system is scheduled for late 1983 and will be followed by refrigerator acceptance tests in 1984. The refrigerator has a design capacity of 24.8 kW at a temperature level near 4K while simultaneously producing 55 kW for heat shield loads at 55K. When completed, the helium refrigerator will be the world's largest. Twenty-five oil-injected screw compressors with an installed total of 23,250 horsepower will supply the gas required. One of the unique features of the cycle is the application of three centrifugal compressors used at liquid helium temperature to produce the low temperatures (2.5K) and high flow rates (4154 g/s) required for this service

Gas and heat dynamics of a micro-scaled atmospheric pressure plasma reference jet

International Nuclear Information System (INIS)

Kelly, Seán; Golda, Judith; Schulz-von der Gathen, Volker; Turner, Miles M

2015-01-01

Gas and heat dynamics of the ‘Cooperation on Science and Technology (COST) Reference Microplasma Jet’ (COST-jet), a European lead reference device for low temperature atmospheric pressure plasma application, are investigated. Of particular interest to many biomedical application scenarios, the temperature characteristics of a surface impacted by the jet are revealed. Schlieren imaging, thermocouple measurements, infrared thermal imaging and numerical modelling are employed. Temperature spatial profiles in the gas domain reveal heating primarily of the helium fraction of the gas mixture. Thermocouple and model temporal data show a bounded exponential temperature growth described by a single characteristic time parameter to reach  ∼63% or (1-1/e) fraction of the temperature increase. Peak temperatures occurred in the gas domain where the carrier jet exits the COST-jet, with values ranging from ambient temperatures to in excess of 100 °C in ‘α-mode’ operation. In a horizontal orientation of the COST-jet a curved trajectory of the helium effluent at low gas flows results from buoyant forces. Gas mixture profiles reveal significant containment of the helium concentrations for a surface placed in close proximity to the COST-jet. Surface heating of a quartz plate follows a similar bounded exponential temporal temperature growth as device heating. Spatial profiles of surface heating are found to correlate strongly to the impacting effluent where peak temperatures occur in regions of maximum surface helium concentration. (paper)

Gas and heat dynamics of a micro-scaled atmospheric pressure plasma reference jet

Science.gov (United States)

Kelly, Seán; Golda, Judith; Turner, Miles M.; Schulz-von der Gathen, Volker

2015-11-01

Gas and heat dynamics of the ‘Cooperation on Science and Technology (COST) Reference Microplasma Jet’ (COST-jet), a European lead reference device for low temperature atmospheric pressure plasma application, are investigated. Of particular interest to many biomedical application scenarios, the temperature characteristics of a surface impacted by the jet are revealed. Schlieren imaging, thermocouple measurements, infrared thermal imaging and numerical modelling are employed. Temperature spatial profiles in the gas domain reveal heating primarily of the helium fraction of the gas mixture. Thermocouple and model temporal data show a bounded exponential temperature growth described by a single characteristic time parameter to reach  ∼63% or (1-1/e) fraction of the temperature increase. Peak temperatures occurred in the gas domain where the carrier jet exits the COST-jet, with values ranging from ambient temperatures to in excess of 100 °C in ‘α-mode’ operation. In a horizontal orientation of the COST-jet a curved trajectory of the helium effluent at low gas flows results from buoyant forces. Gas mixture profiles reveal significant containment of the helium concentrations for a surface placed in close proximity to the COST-jet. Surface heating of a quartz plate follows a similar bounded exponential temporal temperature growth as device heating. Spatial profiles of surface heating are found to correlate strongly to the impacting effluent where peak temperatures occur in regions of maximum surface helium concentration.

Atmospheric nonequilibrium mini-plasma jet created by a 3D printer

Energy Technology Data Exchange (ETDEWEB)

Takamatsu, Toshihiro, E-mail: toshihiro@plasma.es.titech.ac.jp [Kobe University Graduate School of Medicine, Department of Gastroenterology, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017 (Japan); Tokyo Institute of Technology, Department of Energy Sciences, J2-32, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502 (Japan); Kawano, Hiroaki; Miyahara, Hidekazu; Okino, Akitoshi [Tokyo Institute of Technology, Department of Energy Sciences, J2-32, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502 (Japan); Azuma, Takeshi [Kobe University Graduate School of Medicine, Department of Gastroenterology, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017 (Japan)

2015-07-15

In this study, a small-sized plasma jet source with a 3.7 mm head diameter was created via a 3D printer. The jet’s emission properties and OH radical concentrations (generated by argon, helium, and nitrogen plasmas) were investigated using optical emission spectrometry (OES) and electron spin resonance (ESR). As such, for OES, each individual gas plasma propagates emission lines that derive from gases and ambient air inserted into the measurement system. For the case of ESR, a spin adduct of the OH radical is typically observed for all gas plasma treatment scenarios with a 10 s treatment by helium plasma generating the largest amount of OH radicals at 110 μM. Therefore, it was confirmed that a plasma jet source made by a 3D printer can generate stable plasmas using each of the aforementioned three gases.

Liquid helium target

International Nuclear Information System (INIS)

Fujii, Y.; Kitami, T.; Torikoshi, M.

1984-12-01

A liquid helium target system has been built and used for the experiment on the reaction 4 He(γ, p). The target system has worked satisfactorily; the consumption rate of liquid helium is 360 ml/h and the cryogenic system retains liquid helium for about ten hours. The structure, operation and performance of the target system are reported. (author)

Laser cutting technology using water jet waveguide

International Nuclear Information System (INIS)

Akiba, Miyuki; Shiihara, Katsunori; Chida, Itaru

2013-01-01

Laser with water jet is examined to cut in-vessel structure. However, it is necessary to increase the break-up length of water jet to cut a thick plate. Therefore, the effects of the water jet parameter (water pressure, assist gas, laser power) on break-up length were investigated. It was found from observation results of water jet that the longest break-up length is about 135mm under condition of water pressure 40 MPa, laser power 30W and helium assist gas 1L/min. (author)

Gas Mixtures for Welding with Micro-Jet Cooling

Directory of Open Access Journals (Sweden)

Węgrzyn T.

2015-04-01

Full Text Available Welding with micro-jet cooling after was tested only for MIG and MAG processes. For micro-jet gases was tested only argon, helium and nitrogen. A paper presents a piece of information about gas mixtures for micro-jet cooling after in welding. There are put down information about gas mixtures that could be chosen both for MAG welding and for micro-jet process. There were given main information about influence of various micro-jet gas mixtures on metallographic structure of steel welds. Mechanical properties of weld was presented in terms of various gas mixtures selection for micro-jet cooling.

Photoionization of helium dimers

International Nuclear Information System (INIS)

Havermeier, Tilo

2010-01-01

The helium dimer is one of the most weakly bound systems in the universe. This makes it an interesting quantum mechanical object for investigation. These Van der Waals Clusters can be produced in an expansion of a cryogenic gas jet through a small nozzle into vacuum. In the present experiment we examine the interaction of He dimers with synchrotron radiation at an energy range from 64 to 78 eV. We observed different pathways leading to single ionization of both He atoms of the dimer compound. This two close standing ions begin now to dissociate in cause of their coulomb potential. All charged fragments were detected in coincidence with a COLTRIMS system. Especially Interatomic Coulombic Decay (ICD) and the two step process (TS1) were clearly identified. Furthermore a distribution of the internuclear distance was obtained from the measured Kinetic Energy Release (KER). (orig.)

Self-deformation in a direct current driven helium jet micro discharge

International Nuclear Information System (INIS)

Xu, S. F.; Zhong, X. X.

2016-01-01

We report on the experimental observation of three dimensional self-deformation in an atmospheric micro discharge of the helium microjet through a tube into the ambient air upon a water electrode. The geometry of the discharge system is axial symmetric. While decreasing the discharge current, three dimensional collective motion of plasma filaments is directly observed. The three dimensional configuration of the discharge self changed from an axial symmetrical horn to a rectangular horn when the water acts as a cathode

Self-deformation in a direct current driven helium jet micro discharge

Energy Technology Data Exchange (ETDEWEB)

Xu, S. F.; Zhong, X. X., E-mail: xxzhong@sjtu.edu.cn [State Key Laboratory of Advanced Optical Communication Systems and Networks and Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China)

2016-01-15

We report on the experimental observation of three dimensional self-deformation in an atmospheric micro discharge of the helium microjet through a tube into the ambient air upon a water electrode. The geometry of the discharge system is axial symmetric. While decreasing the discharge current, three dimensional collective motion of plasma filaments is directly observed. The three dimensional configuration of the discharge self changed from an axial symmetrical horn to a rectangular horn when the water acts as a cathode.

Self-deformation in a direct current driven helium jet micro discharge

Science.gov (United States)

Xu, S. F.; Zhong, X. X.

2016-01-01

We report on the experimental observation of three dimensional self-deformation in an atmospheric micro discharge of the helium microjet through a tube into the ambient air upon a water electrode. The geometry of the discharge system is axial symmetric. While decreasing the discharge current, three dimensional collective motion of plasma filaments is directly observed. The three dimensional configuration of the discharge self changed from an axial symmetrical horn to a rectangular horn when the water acts as a cathode.

Status of helium-cooled nuclear power systems. [Development potential

Energy Technology Data Exchange (ETDEWEB)

Melese-d' Hospital, G.; Simnad, M

1977-09-01

Helium-cooled nuclear power systems offer a great potential for electricity generation when their long-term economic, environmental, conservation and energy self-sufficiency features are examined. The high-temperature gas-cooled reactor (HTGR) has the unique capability of providing high-temperature steam for electric power and process heat uses and/or high-temperature heat for endothermic chemical reactions. A variation of the standard steam cycle HTGR is one in which the helium coolant flows directly from the core to one or more closed cycle gas turbines. The effective use of nuclear fuel resources for electric power and nuclear process heat will be greatly enhanced by the gas-cooled fast breeder reactor (GCFR) currently being developed. A GCFR using thorium in the radial blanket could generate sufficient U-233 to supply the fuel for three HTGRs, or enough plutonium from a depleted uranium blanket to fuel a breeder economy expanding at about 10% per year. The feasibility of utilizing helium to cool a fusion reactor is also discussed. The status of helium-cooled nuclear energy systems is summarized as a basis for assessing their prospects. 50 references.

The cryogenic helium cooling system for the Tokamak physics experiment

International Nuclear Information System (INIS)

Felker, B.; Slack, D.S.; Wendland, C.R.

1995-01-01

The Tokamak Physics Experiment (TPX) will use supercritical helium to cool all the magnets and supply helium to the Vacuum cryopumping subsystem. The heat loads will come from the standard steady state conduction and thermal radiation sources and from the pulsed loads of the nuclear and eddy currents caused by the Central Solenoid Coils and the plasma positioning coils. The operations of the TPX will begin with pulses of up to 1000 seconds in duration every 75 minutes. The helium system utilizes a pulse load leveling scheme to buffer out the effects of the pulse load and maintain a constant cryogenic plant operation. The pulse load leveling scheme utilizes the thermal mass of liquid and gaseous helium stored in a remote dewar to absorb the pulses of the tokamak loads. The mass of the stored helium will buffer out the temperature pulses allowing 5 K helium to be delivered to the magnets throughout the length of the pulse. The temperature of the dewar will remain below 5 K with all the energy of the pulse absorbed. This paper will present the details of the heat load sources, of the pulse load leveling scheme operations, a partial helium schematic, dewar temperature as a function of time, the heat load sources as a function of time and the helium temperature as a function of length along the various components that will be cooled

Online helium inventory monitoring of JLab cryogenic systems

Science.gov (United States)

Hasan, N.; Knudsen, P.; Wright, M.

2017-12-01

There are five cryogenic plants at Jefferson Lab which support the LINAC, experiment hall end-stations and test facility. The majority of JLab’s helium inventory, which is around 15 tons, is allocated in the LINAC cryo-modules, with the majority of the balance of helium distributed at the cryogenic-plant level mainly as stored gas and liquid for stable operation. Due to the organic evolution of the five plants and independent actions within the experiment halls, the traditional inventory management strategy suffers from rapid identification of potential leaks. This can easily result in losses many times higher than the normally accepted (average) loss rate. A real-time program to quickly identify potential excessive leakage was developed and tested. This program was written in MATLAB© for portability, easy diagnostics and modification. It interfaces directly with EPICS to access the cryogenic system state, and with and NIST REFPROP© for real fluid properties. This program was validated against the actual helium offloaded into the system. The present paper outlines the details of the inventory monitoring program, its validation and a sample of the achieved results.

Transient thermal analysis of cryocondensation pump for JET

International Nuclear Information System (INIS)

Baxi, C.B.; Obert, W.

1993-08-01

A cryopump with pumping speed of 50,000 1/sec is planned to be installed in the Joint European Torus (JET) as part of the pumped divertor. The purpose of this pump is to control the plasma impurities. The pump consists of a helium panel cooled by supercritical helium and a nitrogen shield cooled by liquid nitrogen. This paper presents the following transient thermal flow analysis for this cryopump: 1. Consequences of loss of torus vacuum on helium panel. 2. Cool down of the nitrogen shield form 300 K to 80 K

Formation of excited states in high-Z helium-like systems

International Nuclear Information System (INIS)

Fritzsche, S.; Fricke, B.; Brinzanescu, O.

1999-12-01

High-Z helium-like ions represent the simplest multi-electron systems for studying the interplay between electron-electron correlations, relativistic as well as quantum electrodynamical effects in strong fields. In contrast to the adjacent lithium-like ions, however, almost no experimental information is available about the excited states in the high-Z domain of the helium sequence. Here, we present a theoretical analysis of the X-ray production and decay dynamics of the excited states in helium-like uranium. Emphasize has been paid particularly to the formation of the 3 P 0 and 3 P 2 levels by using electron capture into hydrogen-like U 91+ . Both states are of interest for precise measurements on high-Z helium-like ions in the future. (orig.)

Gaseous Helium storage and management in the cryogenic system for the LHC

CERN Document Server

Barranco-Luque, M

2000-01-01

The Large Hadron Collider (LHC) is presently under construction at CERN. Its main components are superconducting magnets which will operate in superfluid helium requiring cryogenics on a length of about 24 km around the machine ring with a total helium inventory of about 100 tonnes. As no permanent liquid helium storage is foreseen and for reasons of investment costs, only half of the total helium content can be stored in gaseous form in medium pressure vessels. During the LHC operation part of these vessels will be used as helium buffer in the case of multiple magnet quenches. This paper describes the storage, distribution and management of the helium, the layout and the connection to the surface and underground equipment of the cryogenic system.

Reactor helium system, design specification, operation and handling

International Nuclear Information System (INIS)

Badrljica, R.

1984-06-01

Apart from detailed design specification of the helium cover gas system of the Ra reactor, this document includes description of the operating regime, instructions for manipulations in the system with the aim of achieving and maintaining stationary gas circulation [sr

Micro-jet Cooling by Compressed Air after MAG Welding

Directory of Open Access Journals (Sweden)

Węgrzyn T.

2016-06-01

Full Text Available The material selected for this investigation was low alloy steel weld metal deposit (WMD after MAG welding with micro-jet cooling. The present investigation was aimed as the following tasks: analyze impact toughness of WMD in terms of micro-jet cooling parameters. Weld metal deposit (WMD was first time carried out for MAG welding with micro-jet cooling of compressed air and gas mixture of argon and air. Until that moment only argon, helium and nitrogen and its gas mixture were tested for micro-jet cooling.

Accident tolerant high-pressure helium injection system concept for light water reactors

International Nuclear Information System (INIS)

Massey, Caleb; Miller, James; Vasudevamurthy, Gokul

2016-01-01

Highlights: • Potential helium injection strategy is proposed for LWR accident scenarios. • Multiple injection sites are proposed for current LWR designs. • Proof-of-concept experimentation illustrates potential helium injection benefits. • Computational studies show an increase in pressure vessel blowdown time. • Current LOCA codes have the capability to include helium for feasibility calculations. - Abstract: While the design of advanced accident-tolerant fuels and structural materials continues to remain the primary focus of much research and development pertaining to the integrity of nuclear systems, there is a need for a more immediate, simple, and practical improvement in the severe accident response of current emergency core cooling systems. Current blowdown and reflood methodologies under accident conditions still allow peak cladding temperatures to approach design limits and detrimentally affect the integrity of core components. A high-pressure helium injection concept is presented to enhance accident tolerance by increasing operator response time while maintaining lower peak cladding temperatures under design basis and beyond design basis scenarios. Multiple injection sites are proposed that can be adapted to current light water reactor designs to minimize the need for new infrastructure, and concept feasibility has been investigated through a combination of proof-of-concept experimentation and computational modeling. Proof-of-concept experiments show promising cooling potential using a high-pressure helium injection concept, while the developed choked-flow model shows core depressurization changes with added helium injection. Though the high-pressure helium injection concept shows promise, future research into the evaluation of system feasibility and economics are needed.Classification: L. Safety and risk analysis

An advanced regulator for the helium pressurization systems of the Space Shuttle OMS and RCS

Science.gov (United States)

Wichmann, H.

1973-01-01

The Space Shuttle Orbit Maneuvering System and Reaction Control System are pressure-fed rocket propulsion systems utilizing earth storable hypergolic propellants and featuring engines of 6000 lbs and 900 lbs thrust, respectively. The helium pressurization system requirements for these propulsion systems are defined and the current baseline pressurization systems are described. An advanced helium pressure regulator capable of meeting both OMS and RCS helium pressurization system requirements is presented and its operating characteristics and predicted performance characteristics are discussed.

PIV Validation of 3D Multicomponent Model for Cold Spray Within Nitrogen and Helium Supersonic Flow Field

Science.gov (United States)

Faizan-Ur-Rab, M.; Zahiri, S. H.; Masood, S. H.; Jahedi, M.; Nagarajah, R.

2017-06-01

This study presents the validation of a developed three-dimensional multicomponent model for cold spray process using two particle image velocimetry (PIV) experiments. The k- ɛ type 3D model developed for spherical titanium particles was validated with the measured titanium particle velocity within a nitrogen and helium supersonic jet. The 3D model predicted lower values of particle velocity than the PIV experimental study that used irregularly shaped titanium particles. The results of the 3D model were consistent with the PIV experiment that used spherical titanium powder. The 3D model simulation of particle velocity within the helium and nitrogen jet was coupled with an estimation of titanium particle temperature. This was achieved with the consideration of the fact that cold spray particle temperature is difficult and expensive to measure due to considerably lower temperature of particles than thermal spray. The model predicted an interesting pattern of particle size distribution with respect to the location of impact with a concentration of finer particles close to the jet center. It is believed that the 3D model outcomes for particle velocity, temperature and location could be a useful tool to optimize system design, deposition process and mechanical properties of the additively manufactured cold spray structures.

The JET vacuum interspace system

International Nuclear Information System (INIS)

Orchard, J.; Scales, S.

1999-01-01

In the past JET has suffered from a number of vacuum leaks on components such as bellows, windows and feedthroughs due, in part, to the adverse conditions, including high mechanical forces, which may prevail during plasma operation. Therefore before the recent Tritium experiments on JET it was deemed prudent to manufacture and install items with a secondary containment or interspace in order to minimise the effect of failure of the primary vacuum barrier on both the leak integrity of the machine and the outcome of the experiments. This paper describes the philosophy, logistics, method and implementation of an integrated connection and monitoring system on the 330 interspaces currently in position on the JET machine. Using the JET leak database comparisons are drawn of leak failure rates of the components allied to the number of operational hours, prior to the system being present and after installation and commissioning, and the case of detection compared to the previous situation. An argument is also presented on the feasibility and adaptability of this system to any large complex machine and the benefits to be obtained in reduction of leaks and operational down time. (author)

Target and ion source developments for a helium-jet type ISOL at the Kyoto university reactor

International Nuclear Information System (INIS)

Kawase, Yoichi; Okano, Kotoyuki; Funakoshi, Yoshihiro

1985-01-01

A target system and ion sources for a He-jet type ISOL have been successfully constructed and the characteristics have been studied. The beam intensities of short-lived fission products have been much improved by increasing the He gas pressure owing to a range effect of fission products in the He gas and a short transport time effect of aerosols in a target chamber and a capillary. An oscillating electron ion source has been coupled with the He-jet system and ten kinds of elements have been ionized with efficiencies of 0.4-2.4%. A high temperature thermal ion source has been studied to ionize the alkali, alkaline-earth and rare-earth elements. The effects of the He-jet on the ion source have been discussed. (orig.)

Micro-jet Cooling by Compressed Air after MAG Welding

OpenAIRE

Węgrzyn T.; Piwnik J.; Tarasiuk W.; Stanik Z.; Gabrylewski M.

2016-01-01

The material selected for this investigation was low alloy steel weld metal deposit (WMD) after MAG welding with micro-jet cooling. The present investigation was aimed as the following tasks: analyze impact toughness of WMD in terms of micro-jet cooling parameters. Weld metal deposit (WMD) was first time carried out for MAG welding with micro-jet cooling of compressed air and gas mixture of argon and air. Until that moment only argon, helium and nitrogen and its gas mixture were tested for mi...

Numerical and experimental study on a pulsed-dc plasma jet

Science.gov (United States)

Liu, X. Y.; Pei, X. K.; Lu, X. P.; Liu, D. W.

2014-06-01

A numerical and experimental study of plasma jet propagation in a low-temperature, atmospheric-pressure, helium jet in ambient air is presented. A self-consistent, multi-species, two-dimensional axially symmetric plasma model with detailed finite-rate chemistry of helium-air mixture composition is used to provide insights into the propagation of the plasma jet. The obtained simulation results suggest that the sheath forms near the dielectric tube inner surface and shields the plasma channel from the tube surface. The strong electric field at the edge of the dielectric field enhances the ionization in the air mixing layer; therefore, the streamer head becomes ring-shaped when the streamer runs out of the tube. The avalanche-to-streamer transition is the main mechanism of streamer advancement. Penning ionization dominates the ionization reactions and increases the electrical conductivity of the plasma channel. The simulation results are supported by experimental observations under similar discharge conditions.

Performance of the Helium Circulation System on a Commercialized MEG

International Nuclear Information System (INIS)

Takeda, T; Miyazaki, T; Okamoto, M; Katagiri, K

2012-01-01

We report the performance of a helium circulation system (HCS) mounted on a MEG (Magnetoencephalography) at Nagoya University, Japan. This instrument is the first commercialized version of an HCS. The HCS collects warm helium gas at approximately 300 K and then cools it to approximately 40 K. The gas is returned to the neck tube of a Dewar of the MEG to keep it cold. It also collects helium gas in the region just above the liquid helium surface while it is still cold, re-liquefies the gas and returns it to the Dewar. A special transfer tube (TT) of approximately 3 m length was developed to allow for dual helium streams. This tube separates the HCS using a MEG to reduce magnetic noise. A refiner was incorporated to effectively collect contaminating gases by freezing them. The refiner was equipped with an electric heater to remove the frozen contaminants as gases into the air. A gas flow controller was also developed, which automatically controlled the heater and electric valves to clean up contamination. The developed TT exhibited a very low heat inflow of less than 0.1 W/m to the liquid helium, ensuring efficient operation. The insert tube diameter, which was 1.5 in. was reduced to a standard 0.5 in. size. This dimensional change enabled the HCS to mount onto any commercialized MEG without any modifications to the MEG. The HCS can increase liquid helium in the Dewar by at least 3 liters/Day using two GM cryocoolers (SRDK-415D, Sumitomo Heavy Industries, Ltd.). The noise levels were virtually the same as before this installation.

Nitrogen And Oxygen Amount In Weld After Welding With Micro-Jet Cooling

OpenAIRE

Węgrzyn T.; Piwnik J.

2015-01-01

Micro-jet cooling after welding was tested only for MIG welding process with argon, helium and nitrogen as a shielded gases. A paper presents a piece of information about nitrogen and oxygen in weld after micro-jet cooling. There are put down information about gases that could be chosen both for MIG/MAG welding and for micro-jet process. There were given main information about influence of various micro-jet gases on metallographic structure of steel welds. Mechanical properties of weld was pr...

Limitations of superfluid helium droplets as host system revealed by electronic spectroscopy of embedded molecules

Energy Technology Data Exchange (ETDEWEB)

Premke, Tobias

2016-02-19

Superfluid helium nanodroplets serve a unique cryogenic host system ideal to prepare cold molecules and clusters. Structures as well as dynamic processes can be examined by means of high resolution spectroscopy. Dopant spectra are accompanied by helium-induced spectroscopic features which reveal information on the dopant to helium interaction. For this reason the experimental research focuses on the investigation of such helium-induced effects in order to provide new information on the microsolvation inside the droplets. Since the quantitative understanding of helium-induced spectral features is essential to interpret molecular spectra recorded in helium droplets, this study contributes further experimental details on microsolvation in superfluid helium droplets. For this purpose two contrary systems were examined by means of high resolution electronic spectroscopy. The first one, phthalocyanine (Pc), is a planar organic molecule offering a huge and planar surface to the helium atoms and thus, the non-superfluid helium solvation layer can form different structures. The second system is iodine and in contrast to Pc it is of simple molecular shape. That means that in this case different complex structures of the non-superfluid helium solvation layer and the dopant can be expected to be avoided. Thus, both molecules should show clear differences in their microsolvation behavior. In this work a detailed examination of different spectroscopic properties of phthalocyanine is given by means of fluorescence excitation and dispersed emission spectroscopy. It raises legitimate doubts about the assignment of experimentally observed signals to features predicted by the model of the microsolvation. Even though there are no experimental observations which disprove the empirical model for the solvation in helium droplets, an unambiguous assignment of the helium-induced spectroscopic structures is often not possible. In the second part of this work, the investigation of the

Comparing scrape-off layer and divertor physics in JET pure He and D discharges

NARCIS (Netherlands)

Pitts, R.A.; Andrew, P.; Andrew, Y.; Becoulet, M.; Coffey, I.; Coster, D.; McDonald, D. C.; Eich, T.; Erents, S.K.; Fenstermacher, M.E.; Fundamenski, W.; Haas, G.; Hermann, A.; Hidalgo, C.; Hillis, D.; Huber, A.; Ingesson, L. C.; Jachmich, S.; Kallenbach, A.; Korotkov, A.; Lawson, K.; Lomas, P.; Loarer, T.; Loarte, A.; Matthews, G. F.; McCracken, G.; Meigs, A.; Mertens, P.; O' Mullane, M.; Phillipps, V.; Porter, G.; Pospieszczyk, A.; Rapp, J.; Reiter, D.; Riccardo, V.; Saibene, G.; Sartori, R.; Stamp, M. F.; Tsitrone, E.; Wischmeier, W.; Gafert, J.

2003-01-01

Though helium plasmas are one option for the low activation phase of ITER, little effort has thus far been devoted to studying them in a large, diverted tokamak. A recent campaign on JET has therefore sought to address some of the important questions related to helium operation (He concentrations

Comparison between the water activation effects by pulsed and sinusoidal helium plasma jets

Science.gov (United States)

Xu, Han; Liu, Dingxin; Xia, Wenjie; Chen, Chen; Wang, Weitao; Liu, Zhijie; Wang, Xiaohua; Kong, Michael G.

2018-01-01

Comparisons between pulsed and sinusoidal plasma jets have been extensively reported for the discharge characteristics and gaseous reactive species, but rarely for the aqueous reactive species in water solutions treated by the two types of plasma jets. This motivates us to compare the concentrations of aqueous reactive species induced by a pulsed and a sinusoidal plasma jet, since it is widely reported that these aqueous reactive species play a crucial role in various plasma biomedical applications. Experimental results show that the aqueous H2O2, OH/O2-, and O2-/ONOO- induced by the pulsed plasma jet have higher concentrations, and the proportional difference increases with the discharge power. However, the emission intensities of OH(A) and O(3p5P) are higher for the sinusoidal plasma jet, which may be attributed to its higher gas temperature since more water vapor could participate in the plasma. In addition, the efficiency of bacterial inactivation induced by the pulsed plasma jet is higher than that for the sinusoidal plasma jet, in accordance with the concentration relation of aqueous reactive species for the two types of plasma jets.

Simulation of the Direct Digital Synthesis module for Helium RFQ LLRF system

Energy Technology Data Exchange (ETDEWEB)

Jeong, Hae-Seong; Ahn, Tae-Sung; Kim, Seong-Gu; Kwon, Hyeok-Jung; Kim, Han-Sung; Song, Young-Gi; Seol, Kyung-Tae; Cho, Yong-Sub [Korea Atomic Energy Research Institute, Gyeongju (Korea, Republic of)

2015-10-15

In this paper, the DDS module in the FPGA simulated and the analysis result will be introduced. Using Xilinx ISE design suite which is tool for developing the FPGA logic module, DDS module simulated. KOMAC (Korea Multi-purpose Accelerator Complex) has a plan to develop the helium irradiation system. This system includes the Ion source, LEBT, RFQ, MEBT systems to transport helium particles to the target. Especially, the RFQ (Radio Frequency Quadrupole) system should receive the 200 MHz RF within 1% amplitude error stability. For supplying stable 200 MHz RF to the RFQ, the LLRF (low-level radio frequency) should be controlled by control system. This helium RFQ LLRF control system have a concept to track the cavity resonance frequency. For tracking the cavity resonance frequency, the FPGA (Field Programmable Gate Array) in the digital board will tune the frequency of the output sinusoidal signal. In order to implement this frequency tracking concept, the DDS (Direct Digital Synthesis) module should be implemented in the FPGA. In the future, frequency tracking system will be tested using test cavity.

Operating Manual of Helium Refrigerator (Rev. 2)

Energy Technology Data Exchange (ETDEWEB)

Song, K.M.; Son, S.H.; Kim, K.S.; Lee, S.K.; Kim, M.S. [Korea Electric Power Research Institute, Taejon (Korea)

2002-07-01

A helium refrigerator was installed as a supplier of 20K cold helium to the cryogenic distillation system of WTRF pilot plant. The operating procedures of the helium refrigerator, helium compressor and auxiliary apparatus are described for the safety and efficient operation in this manual. The function of the helium refrigerator is to remove the impurities from the compressed helium of about 250psig, to cool down the helium from ambient temperature to 20K through the heat exchanger and expansion engine and to transfer the cold helium to the cryogenic distillation system. For the smoothly operation of helium refrigerator, the preparation, the start-up, the cool-down and the shut-down of the helium refrigerator are described in this operating manual. (author). 3 refs., 14 tabs.

Development of RF non-IQ sampling module for Helium RFQ LLRF system

Energy Technology Data Exchange (ETDEWEB)

Jeong, Hae-Seong; Ahn, Tae-Sung; Kim, Seong-Gu; Kwon, Hyeok-Jung; Kim, Han-Sung; Song, Young-Gi; Seol, Kyung-Tae; Cho, Yong-Sub [KOMAC, Gyeongju (Korea, Republic of)

2015-05-15

KOMAC (Korea Multi-purpose Accelerator Complex) has a plan to develop the helium irradiation system. This system includes the Ion source, LEBT, RFQ, MEBT systems to transport helium particles to the target. Especially, the RFQ (Radio Frequency Quadrupole) system should receive the 200MHz RF within 1% amplitude error stability. For supplying stable 200MHz RF to the RFQ, the low-level radio frequency (LLRF) should be controlled by control system. The helium RFQ LLRF control system adopted non- IQ sampling method to sample the analog input RF. Sampled input data will be calculated to get the I, Q values. These I, Q values will be used to monitor the amplitude and phase of the RF signal. In this paper, non-IQ sampling logic and amplitude and phase calculating logic of the FPGA will be introduced. Using Xilinx ISE design suite which is tool for developing the FPGA logic module, non-IQ sampling module and amplitude and phase computing module developed. In the future, PI gain module and frequency error computing module will be developed.

The maintenance record of the KSTAR helium refrigeration system

Energy Technology Data Exchange (ETDEWEB)

Moon, K. M.; Joo, J. J.; Kim, N. W. [National Fusion Research Institute, Daejeon (Korea, Republic of); and others

2013-12-15

Korea Superconducting Tokamak Advanced Research (KSTAR) has a helium refrigeration system (HRS) with the cooling capacity of 9 kW at 4.5 K. Main cold components are composed of 300 tons of superconducting (SC) magnets, main cryostat thermal shields, and SC current feeder system. The HRS comprises six gas storage tanks, a liquid nitrogen tank, the room temperature compression sector, the cold box (C/B), the 1st stage helium distribution box (DB no.1), the PLC base local control system interconnected to central control tower and so on. Between HRS and cold components, there is another distribution box (DB#2) nearby the KSTAR device. The entire KSTAR device was constructed in 2007 and has been operated since 2008. This paper will present the maintenance result of the KSTAR HRS during the campaign and discuss the operation record and maintenance history of the KSTAR HRS.

Helium turbo-expander with an alternator

International Nuclear Information System (INIS)

Akiyama, Yoshitane

1980-01-01

Study was made on a helium turbo-expander, the heart of helium refrigerator systems, in order to develop a system which satisfies the required conditions. A helium turbo-expander with externally pressurized helium gas bearings at the temperature of liquid nitrogen and an alternator as a brake have been employed. The essential difference between a helium turbo-expander and a nitrogen turbo-expander was clarified. The gas bearing lubricated with nitrogen at room temperature and the gas bearing lubricated with helium at low temperature were tested. The flow rate of helium in a helium refrigerator for a large superconducting magnet is comparatively small, therefore a helium turbine must be small, but the standard for large turbine design can be applied to such small turbine. Using the alternator as a brake, the turbo-expander was easily controllable electrically. The prototype turbo-expander was made, and the liquefaction test with it and MHD power generation test were carried out. (Kako, I.)

Photoionization of helium dimers; Photoionisation von Heliumdimeren

Energy Technology Data Exchange (ETDEWEB)

Havermeier, Tilo

2010-06-09

The helium dimer is one of the most weakly bound systems in the universe. This makes it an interesting quantum mechanical object for investigation. These Van der Waals Clusters can be produced in an expansion of a cryogenic gas jet through a small nozzle into vacuum. In the present experiment we examine the interaction of He dimers with synchrotron radiation at an energy range from 64 to 78 eV. We observed different pathways leading to single ionization of both He atoms of the dimer compound. This two close standing ions begin now to dissociate in cause of their coulomb potential. All charged fragments were detected in coincidence with a COLTRIMS system. Especially Interatomic Coulombic Decay (ICD) and the two step process (TS1) were clearly identified. Furthermore a distribution of the internuclear distance was obtained from the measured Kinetic Energy Release (KER). (orig.)

Mass spectrometric diagnosis of an atmospheric pressure helium microplasma jet

International Nuclear Information System (INIS)

McKay, K; Oh, J-S; Walsh, J L; Bradley, J W

2013-01-01

Ambient molecular beam mass spectrometry (MBMS) has been used to study how different capillary widths (530 µm and 2.4 mm) and excitation waveforms (continuous wave kHz and pulsed dc) affect the ionic composition of atmospheric pressure plasma jets. It is shown from time-averaged ion intensities that reducing the width of the jet capillary results in a significant increase in the variety of both positive and negative ions detected within the discharge. We discuss this in terms of changes in flow velocity and the onset of turbulence within the plasma plume. Changing the mode of excitation had little effect on the ionic species detected from the microplasma jet; however, there was a notable shift in dominance towards higher mass ions when operated in a continuous wave kHz mode. The temporal evolution of the ions within the microplasma jet was observed for both excitation sources, operated at 5 and 15 kHz. Positive ions were created during periods correlated with the positive and negative peaks in discharge current, while negative ions were predominantly created at times when the discharge current peak was negative. This phenomenon was independent of the driving waveform. For pulsed dc excitation, considerably fewer positive ions were created in periods related to the negative current peaks, especially at higher frequencies. We propose a simple explanation for these processes based on ideas of streamer propagation and the influence of self-induced electric fields in the plasma plume. (paper)

Automated recognition of helium speech. Phase I: Investigation of microprocessor based analysis/synthesis system

Science.gov (United States)

Jelinek, H. J.

1986-01-01

This is the Final Report of Electronic Design Associates on its Phase I SBIR project. The purpose of this project is to develop a method for correcting helium speech, as experienced in diver-surface communication. The goal of the Phase I study was to design, prototype, and evaluate a real time helium speech corrector system based upon digital signal processing techniques. The general approach was to develop hardware (an IBM PC board) to digitize helium speech and software (a LAMBDA computer based simulation) to translate the speech. As planned in the study proposal, this initial prototype may now be used to assess expected performance from a self contained real time system which uses an identical algorithm. The Final Report details the work carried out to produce the prototype system. Four major project tasks were: a signal processing scheme for converting helium speech to normal sounding speech was generated. The signal processing scheme was simulated on a general purpose (LAMDA) computer. Actual helium speech was supplied to the simulation and the converted speech was generated. An IBM-PC based 14 bit data Input/Output board was designed and built. A bibliography of references on speech processing was generated.

Exergy analysis of helium liquefaction systems based on modified Claude cycle with two-expanders

Science.gov (United States)

Thomas, Rijo Jacob; Ghosh, Parthasarathi; Chowdhury, Kanchan

2011-06-01

Large-scale helium liquefaction systems, being energy-intensive, demand judicious selection of process parameters. An effective tool for design and analysis of thermodynamic cycles for these systems is exergy analysis, which is used to study the behavior of a helium liquefaction system based on modified Claude cycle. Parametric evaluation using process simulator Aspen HYSYS® helps to identify the effects of cycle pressure ratio and expander flow fraction on the exergetic efficiency of the liquefaction cycle. The study computes the distribution of losses at different refrigeration stages of the cycle and helps in selecting optimum cycle pressures, operating temperature levels of expanders and mass flow rates through them. Results from the analysis may help evolving guidelines for designing appropriate thermodynamic cycles for practical helium liquefaction systems.

Implications of Upwells as Hydrodynamic Jets in a Pulse Jet Mixed System

Energy Technology Data Exchange (ETDEWEB)

Pease, Leonard F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bamberger, Judith A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Minette, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2017-02-28

This report evaluates the physics of the upwell flow in pulse jet mixed systems in the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Although the initial downward flow and radial flow from jets characteristic of pulse jet mixers (PJMs) has been analyzed, the upwells have received considerably less attention despite having significant implications for vessel mixing. Do the upwells behave like jets? How do the upwells scale? When will the central upwell break through? What proportion of the vessel is blended by the upwells themselves? Indeed, how the physics of the central upwell is affected by multiple PJMs (e.g., six in the proposed mixing vessels), non-Newtonian rheology, and significant multicomponent solids loadings remain unexplored.

Thirty years of screw compressors for helium; Dreissig Jahre Schraubenkompressoren fuer Helium

Energy Technology Data Exchange (ETDEWEB)

Wahl, H. [Kaeser Kompressoren GmbH, Coburg (Germany). Technisches Buero/Auftragskonstruktion

2007-07-01

KAESER helium compressors, as well as their other industrial compressors, will be further developed with the intention to improve the availability and reliability of helium liquefaction systems. Further improvement of compressor and control system efficiency will ensure a low and sustainable operating cost. Fast supply of replacement parts with several years of warranty is ensured by a world-wide distribution system and is also worked on continuously. (orig.)

Isotope separation in crossed-jet systems

Energy Technology Data Exchange (ETDEWEB)

Gallagher, R.J.; Anderson, J.B.

1978-11-01

The separation of isotopes in crossed-jet systems was investigated with Monte Carlo calculations of the separation effects for jets of Ne/Ar and /sup 235/UF/sub 6///sup 238/UF/sub 6/ mixtures entering a hydrogen stream. For the ideal condition of uniform stream velocities at zero temperature, the separation factor ..cap alpha.. was found to be 16.0 for Ne/Ar and 1.17 for /sup 235/UF/sub 6///sup 238/UF/sub 6/. For less ideal but more practical conditions, Monte Carlo calculations of the complete crossed-jet systems gave separation factors as high as 3.3 for Ne/Ar and ..cap alpha.. = 1.046 - 1.078 for /sup 235/UF/sub 6///sup 238/UF/sub 6/.

Optical Emission Spectroscopy of an Atmospheric Pressure Plasma Jet During Tooth Bleaching Gel Treatment.

Science.gov (United States)

Šantak, Vedran; Zaplotnik, Rok; Tarle, Zrinka; Milošević, Slobodan

2015-11-01

Optical emission spectroscopy was performed during atmospheric pressure plasma needle helium jet treatment of various tooth-bleaching gels. When the gel sample was inserted under the plasma plume, the intensity of all the spectral features increased approximately two times near the plasma needle tip and up to two orders of magnitude near the sample surface. The color change of the hydroxylapatite pastille treated with bleaching gels in conjunction with the atmospheric pressure plasma jet was found to be in correlation with the intensity of OH emission band (309 nm). Using argon as an additive to helium flow (2 L/min), a linear increase (up to four times) of OH intensity and, consequently, whitening (up to 10%) of the pastilles was achieved. An atmospheric pressure plasma jet activates bleaching gel, accelerates OH production, and accelerates tooth bleaching (up to six times faster).

Hybrid Reynolds-Averaged/Large-Eddy Simulations of a Coaxial Supersonic Free-Jet Experiment

Science.gov (United States)

Baurle, Robert A.; Edwards, Jack R.

2010-01-01

Reynolds-averaged and hybrid Reynolds-averaged/large-eddy simulations have been applied to a supersonic coaxial jet flow experiment. The experiment was designed to study compressible mixing flow phenomenon under conditions that are representative of those encountered in scramjet combustors. The experiment utilized either helium or argon as the inner jet nozzle fluid, and the outer jet nozzle fluid consisted of laboratory air. The inner and outer nozzles were designed and operated to produce nearly pressure-matched Mach 1.8 flow conditions at the jet exit. The purpose of the computational effort was to assess the state-of-the-art for each modeling approach, and to use the hybrid Reynolds-averaged/large-eddy simulations to gather insight into the deficiencies of the Reynolds-averaged closure models. The Reynolds-averaged simulations displayed a strong sensitivity to choice of turbulent Schmidt number. The initial value chosen for this parameter resulted in an over-prediction of the mixing layer spreading rate for the helium case, but the opposite trend was observed when argon was used as the injectant. A larger turbulent Schmidt number greatly improved the comparison of the results with measurements for the helium simulations, but variations in the Schmidt number did not improve the argon comparisons. The hybrid Reynolds-averaged/large-eddy simulations also over-predicted the mixing layer spreading rate for the helium case, while under-predicting the rate of mixing when argon was used as the injectant. The primary reason conjectured for the discrepancy between the hybrid simulation results and the measurements centered around issues related to the transition from a Reynolds-averaged state to one with resolved turbulent content. Improvements to the inflow conditions were suggested as a remedy to this dilemma. Second-order turbulence statistics were also compared to their modeled Reynolds-averaged counterparts to evaluate the effectiveness of common turbulence closure

Gas stratification break-up by a vertical jet: Simulations using the GOTHIC code

International Nuclear Information System (INIS)

Andreani, Michele; Kapulla, Ralf; Zboray, Robert

2012-01-01

Highlights: ► Simulations of experiments addressing helium stratification break-up with GOTHIC are presented. ► In the tests, the initial helium-rich layer in a large vessel is eroded by a vertical jet. ► A 3-D coarse mesh and various finer 2-D meshes have been used for the simulations. ► In general, the 3-D calculations predict too slow mixing in the vessel. ► A reasonable agreement between calculated and measured gas concentrations requires a fine mesh. - Abstract: The capability assessment of three-dimensional computational tools to predict the erosion and the break-up of stratified conditions that can build-up in a containment through the release of hydrogen during an early phase of a hypothetical severe accident is the focus of intense research worldwide. In conjunction with the OECD SETH-2 project, the GOTHIC code is assessed against experiments in which mass and/or heat sources or sinks cause mixing. This paper reports on simulation results of selected experiments where the initial helium stratification in a vessel is eroded by a vertical jet originating from an injection below the initial density interface. A 3-D coarse mesh, as well as various finer 2-D meshes, is used to simulate the evolution of the helium distribution generated by jets having different initial momentum. In general, the 3-D calculations predict too slow mixing in the vessel and a reasonable agreement between calculated and measured gas concentrations can only be achieved with a sufficiently fine mesh. These results can be explained by comparing the calculated velocity field with that measured using the PIV technique, which also provides valuable insight into the mechanisms of the interaction between the jet and the density interface.

Helium dilution refrigerator

International Nuclear Information System (INIS)

1973-01-01

A new system of continuous heat exchange for a helium dilution refrigerator is proposed. The 3 He effluent tube is concurrent with the affluent mixed helium tube in a vertical downward direction. Heat exchange efficiency is enhanced by placing in series a number of elements with an enlarged surface area

X-ray Jets in the CH Cyg Symbiotic System

Science.gov (United States)

Karovska, Margarita; Gaetz, T.; Lee, N.; Raymond, J.; Hack, W.; Carilli, C.

2009-09-01

Symbiotic binaries are interacting systems in which a compact stellar source accretes matter from the wind of the cool evolved companion. There are a few hundred symbiotic systems known today, but jet activity has been detected in only a few of them, including in CH Cyg. CH Cyg is a symbiotic system that has shown significant activity since the mid 1960s. Jets have been detected in optical and radio since 1984, and more recently in 2001 in X-rays using Chandra observations.In 2008 we carried out coordinated multi-wavelength observations of the CH Cyg system with Chandra, HST, and the VLA, in order to study the propagation and interaction with the circumbinary medium of the jet detected in 2001. We report here on the detection of the 2001 SE jet which has expanded in seven years from ˜350AU to ˜1400 AU. The apex of the loop delineating the region of interaction with the circumbinary matter is moving with a speed of ˜700 km/s. Assuming a linear expansion, the jet was launched during the 1999-2000 active phase. We also report on a detection of a powerful new jet in the SW direction, observed in X-ray, optical and radio wavelengths. The new jet has a multi-component structure including an inner jet and counter jet, and a SW component ending in several clumps extending up to a distance of about 750AU.

Stimulation of wound healing by helium atmospheric pressure plasma treatment

International Nuclear Information System (INIS)

Nastuta, Andrei Vasile; Topala, Ionut; Pohoata, Valentin; Popa, Gheorghe; Grigoras, Constantin

2011-01-01

New experiments using atmospheric pressure plasma have found large application in treatment of living cells or tissues, wound healing, cancerous cell apoptosis, blood coagulation on wounds, bone tissue modification, sterilization and decontamination. In this study an atmospheric pressure plasma jet generated using a cylindrical dielectric-barrier discharge was applied for treatment of burned wounds on Wistar rats' skin. The low temperature plasma jet works in helium and is driven by high voltage pulses. Oxygen and nitrogen based impurities are identified in the jet by emission spectroscopy. This paper analyses the natural epithelization of the rats' skin wounds and two methods of assisted epithelization, a classical one using polyurethane wound dressing and a new one using daily atmospheric pressure plasma treatment of wounds. Systemic and local medical data, such as haematological, biochemical and histological parameters, were monitored during entire period of study. Increased oxidative stress was observed for plasma treated wound. This result can be related to the presence in the plasma volume of active species, such as O and OH radicals. Both methods, wound dressing and plasma-assisted epithelization, provided positive medical results related to the recovery process of burned wounds. The dynamics of the skin regeneration process was modified: the epidermis re-epitelization was accelerated, while the recovery of superficial dermis was slowed down.

Nitrogen And Oxygen Amount In Weld After Welding With Micro-Jet Cooling

Directory of Open Access Journals (Sweden)

Węgrzyn T.

2015-06-01

Full Text Available Micro-jet cooling after welding was tested only for MIG welding process with argon, helium and nitrogen as a shielded gases. A paper presents a piece of information about nitrogen and oxygen in weld after micro-jet cooling. There are put down information about gases that could be chosen both for MIG/MAG welding and for micro-jet process. There were given main information about influence of various micro-jet gases on metallographic structure of steel welds. Mechanical properties of weld was presented in terms of nitrogen and oxygen amount in WMD (weld metal deposit.

21 CFR 876.4650 - Water jet renal stone dislodger system.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Water jet renal stone dislodger system. 876.4650... (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4650 Water jet renal stone dislodger system. (a) Identification. A water jet renal stone dislodger system is a device used to...

System evaluation of improved thermal stability jet fuels

Energy Technology Data Exchange (ETDEWEB)

Binns, K.E.; Dieterle, G.L.; Williams, T. [Univ. of Dayton Research Institute, OH (United States)

1995-05-01

A single-pass, single-tube heat exchanger device called the Phoenix rig and a single-pass, dual-heat exchanger system called the Extended Duration Thermal Stability Test system are specific devices/systems developed for evaluating jet fuel thermal stability. They have been used extensively in the evaluation of various jet fuels and thermal stability additives. The test results have indicated that additives can substantially improve the thermal stability of conventional jet fuels. Relationships of oxygen consumption, residence time, bulk, and wetted wall temperatures on coking deposits that form in the heated tubes have also been investigated.

A numerical study on transient high speed free jet into a confined enclosure

International Nuclear Information System (INIS)

Chae, K.M.; Yoo, S.Y.; Rhee, W.; Hangbok, Choi

2001-01-01

In a CANDU type reactor, one of the 2 independent shutdown systems is a liquid poison injection system (SDS2). The longest poison injector is 21 pitches long. There are 4 nozzle positions per lattice pitch (287.75 mm) and 4 holes per nozzle position. A numerical model is developed in this study to systematically and consistently estimate the concentration and diffusion of the poison injected from SDS2. In order to assess the source-jet model, a comparison was made against the real-jet calculation using actual boundary conditions. The simulation was performed in two-dimensional geometry with 4 nozzle holes aligned in 1 lattice pitch and an injection velocity of 20 m/s. The study has shown that the source-jet model agrees with the experimental results and real-jet simulation. It was also found that the source-jet model can be effectively used for the simulation of liquid poison injection through small holes, of which the simulation is restricted due to the limitation of number of grid points in the real-jet simulation. The source-term model of the liquid poison injection developed in this study is consistent with the actual poison injection system in a CANDU 6 reactor and, therefore, can generate poison concentration data for the safety analysis of the reactor. In the future, it is strongly recommended to perform further study to analyze the transient of the poison injection from helium tank to injection nozzle hole by applying Bernoulli equation

Low Alloy Steel Structures After Welding with Micro-Jet Cooling

Directory of Open Access Journals (Sweden)

Węgrzyn T.

2017-03-01

Full Text Available The paper focuses on low alloy steel after innovate welding method with micro-jet cooling. Weld metal deposit (WMD was carried out for welding and for MIG and MAG welding with micro-jet cooling. This method is very promising mainly due to the high amount of AF (acicular ferrite and low amount of MAC (self-tempered martensite, retained austenite, carbide phases in WMD. That structure corresponds with very good mechanical properties, ie. high impact toughness of welds at low temperature. Micro-jet cooling after welding can find serious application in automotive industry very soon. Until that moment only argon, helium and nitrogen were tested as micro-jet gases. In that paper first time various gas mixtures (gas mixtures Ar-CO2 were tested for micro-jet cooling after welding.

Noble gas enrichment studies at JET

International Nuclear Information System (INIS)

Groth, M.; Andrew, P.; Fundamenski, W.; Guo, H.Y.; Hillis, D.L.; Hogan, J.T.; Horton, L.D.; Matthews, G.F.; Meigs, A.G.; Morgan, P.M.; Stamp, M.F.; Hellermann, M. von

2001-01-01

Adequate helium exhaust has been achieved in reactor-relevant ELMy H-mode plasmas in JET performed in the MKII AP and MKII GB divertor geometry. The divertor-characteristic quantities of noble gas compression and enrichment have been experimentally inferred from Charge Exchange Recombination Spectroscopy measurements in the core plasma, and from spectroscopic analysis of a Penning gauge discharge in the exhaust gas. The retention of helium was found to be satisfactory for a next-step device, with enrichment factors exceeding 0.1. The helium enrichment decreases with increasing core plasma density, while the neon enrichment has the opposite behaviour. Analytic and numerical analyses of these plasmas using the divertor impurity code package DIVIMP/NIMBUS support the explanation that the enrichment of noble gases depends significantly on the penetration depth of the impurity neutrals with respect to the fuel atoms. Changes of the divertor plasma configuration and divertor geometry have no effect on the enrichment

The liquid helium system of ATLAS

International Nuclear Information System (INIS)

Nixon, J.M.; Bollinger, L.M.

1989-01-01

Starting in 1978 with one small refrigerator and distribution line, the LHe system of ATLAS has gradually grown into a complex network, as required by several enlargements of the superconducting linac. The cryogenic system now comprises 3 refrigerators, 11 helium compressors, /approximately/340 ft. of coaxial LHe transfer line, 3 1000-l dewars, and /approximately/76 LHe valves that deliver steady-state flowing LHe to 16 beam-line cryostats. In normal operation, the 3 refrigerators are linked so as to provide cooling where needed. LHe heat exchangers in distribution lines play an important role. This paper discusses design features of the system, including the logic of the controls that permit the coupled refrigerators to operate stably in the presence of large and sudden changes in heat load. 8 refs., 3 figs

The system architecture of the new JET Shape Controller

International Nuclear Information System (INIS)

Sartori, F.; Ambrosino, G.; Ariola, M.; Cenedese, A.; Crisanti, F.; Tommasi, G. De; Cullen, P. Mc; Piccolo, F.; Pironti, A.

2005-01-01

This paper describes the installation of the new JET Shape Controller System [M. Garribba, R. Litunovsky, P. Noll, S. Puppin, The new control scheme for the JET plasma position and current control system, in: Proceedings of the 15th SOFE Conference, Massachusetts, 1993, pp. 33-36; F. Sartori, A. Cenedese, Plasma position and current control management at JET, in: Proceedings of the 42nd IEEE Conference on Decision and Control, Maui, 2003] especially focusing on the addition of the Extreme Shape Controller [G. Ambrosino, et al., A new shape controller for extremely shaped plasmas in JET, Fusion Eng. Des. 66-68 (2003) 797-802]. The activity was performed by the JET Operator in co-operation with the ENEA-CREATE design team, and involved both changes in the hardware and system software of JET and tuning of the proposed Extreme Shape Controller (XSC) design to satisfy the practical requirements of tokamak operation. The application of 10 years experience of controller implementation and commissioning combined with a modern and efficient modelling and design methodology has allowed an unprecedented fast and easy commissioning of the new system

Lighting system with thermal management system having point contact synthetic jets

Science.gov (United States)

Arik, Mehmet; Weaver, Stanton Earl; Kuenzler, Glenn Howard; Wolfe, Jr., Charles Franklin; Sharma, Rajdeep

2013-12-10

Lighting system having unique configurations are provided. For instance, the lighting system may include a light source, a thermal management system and driver electronics, each contained within a housing structure. The light source is configured to provide illumination visible through an opening in the housing structure. The thermal management system includes a plurality of synthetic jets. The synthetic jets are arranged within the lighting system such that they are secured at contact points.

Helium heater design for the helium direct cycle component test facility. [for gas-cooled nuclear reactor power plant

Science.gov (United States)

Larson, V. R.; Gunn, S. V.; Lee, J. C.

1975-01-01

The paper describes a helium heater to be used to conduct non-nuclear demonstration tests of the complete power conversion loop for a direct-cycle gas-cooled nuclear reactor power plant. Requirements for the heater include: heating the helium to a 1500 F temperature, operating at a 1000 psia helium pressure, providing a thermal response capability and helium volume similar to that of the nuclear reactor, and a total heater system helium pressure drop of not more than 15 psi. The unique compact heater system design proposed consists of 18 heater modules; air preheaters, compressors, and compressor drive systems; an integral control system; piping; and auxiliary equipment. The heater modules incorporate the dual-concentric-tube 'Variflux' heat exchanger design which provides a controlled heat flux along the entire length of the tube element. The heater design as proposed will meet all system requirements. The heater uses pressurized combustion (50 psia) to provide intensive heat transfer, and to minimize furnace volume and heat storage mass.

Relation between the conditions of helium ion implantation and helium void equilibrium parameters

International Nuclear Information System (INIS)

Neklyudov, I.M.; Rybalko, V.F.; Ruzhitskij, V.V.; Tolstolutskaya, G.D.

1981-01-01

The conditions of helium thermodynamic equilibrium in a system of voids produced by helium ion bombardment of a metal sample are studied. As an initial equation for description of the equilibrium the Clapeyron equation was used. The equation is obtained relating basic parameters of helium voids (average diameter and density) to irradiation parameters (dose, ion energy (straggling)) and properties of the metal (surface tension coefficient, yield strength). Comparison of the calculations with experimental data on helium in nickel found in literature shows that the equation yields satisfactory resutls for the dose range 1.10 16 -1x10 17 cm -2 and temperatures T [ru

Theoretical Study of Triatomic Systems Involving Helium Atoms

International Nuclear Information System (INIS)

Suno, H.; Hiyama, E.; Kamimura, M.

2013-01-01

The triatomic 4 He system and its isotopic species 4 He 2 3 He are theoretically investigated. By adopting the best empirical helium interaction potentials, we calculate the bound state energy levels as well as the rates for the three-body recombination processes: 4 He + 4 He + 4 He → 4 He 2 + 4 He and 4 He + 4 He + 3 He → 4 He 2 + 3 He. We consider not only zero total angular momentum J = 0 states, but also J > 0 states. We also extend our study to mixed helium-alkali triatomic systems, that is 4 He 2 X with X = 7 Li, 23 Na, 39 K, 85 Rb, and 133 Cs. The energy levels of all the J ≥ 0 bound states for these species are calculated as well as the rates for three-body recombination processes such as 4 He + 4 He + 7 Li → 4 He 2 + 7 Li and 4 He + 4 He + 7 Li → 4 He 7 Li + 4 He. In our calculations, the adiabatic hyperspherical representation is employed but we also obtain preliminary results using the Gaussian expansion method. (author)

Magnetotransport in a quasi-one-dimensional electron system over superfluid helium

CERN Document Server

Nikolaenko, V A; Gladchenko, S P

2002-01-01

Magnetotransport in a nondegenerate quasi-one-dimensional electron system (Q1D) over superfluid helium is investigated experimentally. The experiments were carried out at perpendicular magnetic fields, B 0.9 K) and the electron-ripplon scattering (T 1(here omega sub c is the cyclotron frequency and t is the relaxation time of the electron system) agree qualitatively with the self-consistent Born approximation theory for a 2D electron system over helium. It is supposed that the quantitative discrepancies in the experimental and theoretical data are connected with different peculiar features of the investigated and analyzed electron systems. The experimental data on electron mobility at low temperatures and small magnetic fields coincide with the theoretical calculation made for the Q1D system. The negative magnetoresistance of the channels observed both in the electron-gas scattering and electron-ripplon scattering regions is supposed to be due to weak localization of carriers in the investigated electron syst...

Friendly fermions of helium-three

International Nuclear Information System (INIS)

Leggatt, T.

1976-01-01

The importance of helium in showing up the effects of atomic indistinguishability and as a material by which to test some of the most fundamental principles of quantum mechanics is discussed. Helium not only remains liquid down to zero temperature but of the two isotopes helium-three has intrinsic spin 1/2 and should therefore obey the Pauli principle, while helium-four has spin zero and is expected to undergo Bose condensation. Helium-three becomes superfluid at temperatures of a few thousandths of a degree above absolute zero by the bulk liquid collecting its atoms into spinning pairs. There are three different superfluid phases, now conveniently called A, B and A 1 and each is characterised by a different behaviour of the spin and/or relative angular motion of the atoms composing the Cooper pairs. Problems surrounding the complicated physical system of helium-three are discussed. It is suggested that the combined coherence and directionality of superfluid helium-three should create some fascinating physics. (U.K.)

Influence of MHD effects and edge conditions on ITER helium ash accumulation and sustained ignition

International Nuclear Information System (INIS)

Redi, M.H.; Cohen, S.A.

1990-06-01

Dilution of reacting species by build-up of helium ash and its effect on ignition in the ITER tokamak have been studies in a series of simulations with the one-dimensional BALDUR transport code. Thermal diffusivities, obtained from ITER scaling laws and with radial variations observed in JET, gave τ E ∼ 2--4 sec. Refueling of deuterium and tritium maintained constant electron density, while carbon recycling was 100% and the helium ash recycling was varied from 1.0 to 0.5. Including MHD effects, specifically sawteeth and beta limits, we find that ignition can be sustained for 200 seconds with R helium = 0.95. These simulations, the only non-zero-dimensional, time-dependent simulations thus far made for ITER plasmas, emphasize that edge plasma conditions, MHD behavior, and helium particle transport are critical synergistic issues for sustained ignition. 27 refs., 2 figs., 1 tab

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.

The design of an ECRH system for JET-EP

DEFF Research Database (Denmark)

Verhoeven, A.G.A.; Bongers, W.A.; Elzendoorn, B.S.Q.

2003-01-01

An electron cyclotron resonance heating (ECRH) system has been designed for JET in the framework of the JET enhanced performance project (JET-EP) under the European fusion development agreement. Due to financial constraints it has been decided not to implement this project. Nevertheless, the design...

The design of an ECRH system for JET-EP

NARCIS (Netherlands)

Verhoeven, A. G. A.; Bongers, W. A.; Elzendoorn, B. S. Q.; Graswinckel, M.; Hellingman, P.; Kooijman, W.; Kruijt, O. G.; Maagdenberg, J.; Ronden, D.; Stakenborg, J.; Sterk, A. B.; Tichler, J.; Alberti, S.; Goodman, T.; Henderson, M.; Hoekzema, J. A.; Oosterbeek, J. W.; Fernandez, A.; Likin, K.; Bruschi, A.; Cirant, S.; Novaks, S.; Piosczyk, B.; Thumm, M.; Bindslev, H.; Kaye, A.; Fleming, C.; Zohm, H.

2003-01-01

An electron cyclotron resonance heating (ECRH) system has been designed for JET in the framework of the JET enhanced performance project (JET-EP) under the European fusion development agreement. Due to financial constraints it has been decided not to implement this project. Nevertheless, the design

Dynamics of Superfluid Helium in Low-Gravity

Science.gov (United States)

Frank, David J.

1997-01-01

This report summarizes the work performed under a contract entitled 'Dynamics of Superfluid Helium in Low Gravity'. This project performed verification tests, over a wide range of accelerations of two Computational Fluid Dynamics (CFD) codes of which one incorporates the two-fluid model of superfluid helium (SFHe). Helium was first liquefied in 1908 and not until the 1930s were the properties of helium below 2.2 K observed sufficiently to realize that it did not obey the ordinary physical laws of physics as applied to ordinary liquids. The term superfluidity became associated with these unique observations. The low temperature of SFHe and it's temperature unifonrmity have made it a significant cryogenic coolant for use in space applications in astronomical observations with infrared sensors and in low temperature physics. Superfluid helium has been used in instruments such as the Shuttle Infrared Astronomy Telescope (IRT), the Infrared Astronomy Satellite (IRAS), the Cosmic Background Observatory (COBE), and the Infrared Satellite Observatory (ISO). It is also used in the Space Infrared Telescope (SIRTF), Relativity Mission Satellite formally called Gravity Probe-B (GP-B), and the Test of the Equivalence Principle (STEP) presently under development. For GP-B and STEP, the use of SFHE is used to cool Superconducting Quantum Interference Detectors (SQUIDS) among other parts of the instruments. The Superfluid Helium On-Orbit Transfer (SHOOT) experiment flown in the Shuttle studied the behavior of SFHE. This experiment attempted to get low-gravity slosh data, however, the main emphasis was to study the low-gravity transfer of SFHE from tank to tank. These instruments carried tanks of SFHE of a few hundred liters to 2500 liters. The capability of modeling the behavior of SFHE is important to spacecraft control engineers who must design systems that can overcome disturbances created by the movement of the fluid. In addition instruments such as GP-B and STEP are very

Diagnostics of an AC driven atmospheric pressure non-thermal plasma jet and its use for radially directed jet array

Science.gov (United States)

Zhu, W.; Wang, R.

2017-08-01

An alternating current atmospheric pressure plasma jet is generated with noble gas or noble gas/oxygen admixture as working gas. A "core plasma filament" is observed at the center of the dielectric tube and extends to the plasma jet at higher peak-to-peak voltages. This type of plasma jet is believed to be of the same nature with the reported plasma bullet driven by pulsed DC power sources. Double current probes are used to assess the speed of the plasma bullet and show that the speed is around 104-105 m/s. The time dependence of the downstream bullet speed is attributed to the gas heating and in turn the increase of the reduced electric field E/N. Optical emission spectra show the dependence of helium and oxygen emission intensities on the concentration of oxygen additive in the carrier gas, with peak values found at 0.5% O2. Multiple radial jets are realized on dielectric tubes of different sizes. As a case study, one of these multi-jet devices is used to treat B. aureus on the inner surface of a plastic beaker and is shown to be more effective than a single jet.

Hybrid Reynolds-Averaged/Large-Eddy Simulations of a Co-Axial Supersonic Free-Jet Experiment

Science.gov (United States)

Baurle, R. A.; Edwards, J. R.

2009-01-01

Reynolds-averaged and hybrid Reynolds-averaged/large-eddy simulations have been applied to a supersonic coaxial jet flow experiment. The experiment utilized either helium or argon as the inner jet nozzle fluid, and the outer jet nozzle fluid consisted of laboratory air. The inner and outer nozzles were designed and operated to produce nearly pressure-matched Mach 1.8 flow conditions at the jet exit. The purpose of the computational effort was to assess the state-of-the-art for each modeling approach, and to use the hybrid Reynolds-averaged/large-eddy simulations to gather insight into the deficiencies of the Reynolds-averaged closure models. The Reynolds-averaged simulations displayed a strong sensitivity to choice of turbulent Schmidt number. The baseline value chosen for this parameter resulted in an over-prediction of the mixing layer spreading rate for the helium case, but the opposite trend was noted when argon was used as the injectant. A larger turbulent Schmidt number greatly improved the comparison of the results with measurements for the helium simulations, but variations in the Schmidt number did not improve the argon comparisons. The hybrid simulation results showed the same trends as the baseline Reynolds-averaged predictions. The primary reason conjectured for the discrepancy between the hybrid simulation results and the measurements centered around issues related to the transition from a Reynolds-averaged state to one with resolved turbulent content. Improvements to the inflow conditions are suggested as a remedy to this dilemma. Comparisons between resolved second-order turbulence statistics and their modeled Reynolds-averaged counterparts were also performed.

Application of JLab 12GeV helium refrigeration system for the FRIB accelerator at MSU

International Nuclear Information System (INIS)

Ganni, V.; Knudsen, P.; Arenius, D.; Casagrande, F.

2014-01-01

The planned approach to have a turnkey helium refrigeration system for the MSU-FRIB accelerator system, encompassing the design, fabrication, installation and commissioning of the 4.5-K refrigerator cold box(es), cold compression system, warm compression system, gas management, oil removal and utility/ancillary systems, was found to be cost prohibitive. Following JLab’s suggestion, MSU-FRIB accelerator management made a formal request to evaluate the applicability of the recently designed 12GeV JLab cryogenic system for this application. The following paper will outline the findings and the planned approach for the FRIB helium refrigeration system

Evolving the JET virtual reality system for delivering the JET EP2 shutdown remote handling tasks

Energy Technology Data Exchange (ETDEWEB)

Williams, Adrian, E-mail: adrian.williams@oxfordtechnologies.co.uk [Oxford Technologies Ltd., 7 Nuffield Way, Abingdon, Oxon, OX14 1RJ (United Kingdom); JET-EFDA, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Sanders, Stephen [Oxford Technologies Ltd., 7 Nuffield Way, Abingdon, Oxon, OX14 1RJ (United Kingdom); JET-EFDA, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Weder, Gerard [Tree-C Technology BV, Buys Ballotstraat 8, 6716 BL Ede (Netherlands); JET-EFDA, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Bastow, Roger; Allan, Peter; Hazel, Stuart [CCFE, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); JET-EFDA, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom)

2011-10-15

The quality, functionality and performance of the virtual reality (VR) system used at JET for preparation and implementation of remote handling (RH) operations has been progressively enhanced since its first use in the original JET remote handling shutdown in 1998. As preparation began for the JET EP2 (Enhanced Performance 2) shutdown it was recognised that the VR system being used was unable to cope with the increased functionality and the large number of 3D models needed to fully represent the JET in-vessel components and tooling planned for EP2. A bespoke VR software application was developed in collaboration with the OEM, which allowed enhancements to be made to the VR system to meet the requirements of JET remote handling in preparation for EP2. Performance improvements required to meet the challenges of EP2 could not be obtained from the development of the new VR software alone. New methodologies were also required to prepare source, CATIA models for use in the VR using a collection of 3D software packages. In collaboration with the JET drawing office, techniques were developed within CATIA using polygon reduction tools to reduce model size, while retaining surface detail at required user limits. This paper will discuss how these developments have played an essential part in facilitating EP2 remote handling task development and examine their impact during the EP2 shutdown.

Evolving the JET virtual reality system for delivering the JET EP2 shutdown remote handling tasks

International Nuclear Information System (INIS)

Williams, Adrian; Sanders, Stephen; Weder, Gerard; Bastow, Roger; Allan, Peter; Hazel, Stuart

2011-01-01

The quality, functionality and performance of the virtual reality (VR) system used at JET for preparation and implementation of remote handling (RH) operations has been progressively enhanced since its first use in the original JET remote handling shutdown in 1998. As preparation began for the JET EP2 (Enhanced Performance 2) shutdown it was recognised that the VR system being used was unable to cope with the increased functionality and the large number of 3D models needed to fully represent the JET in-vessel components and tooling planned for EP2. A bespoke VR software application was developed in collaboration with the OEM, which allowed enhancements to be made to the VR system to meet the requirements of JET remote handling in preparation for EP2. Performance improvements required to meet the challenges of EP2 could not be obtained from the development of the new VR software alone. New methodologies were also required to prepare source, CATIA models for use in the VR using a collection of 3D software packages. In collaboration with the JET drawing office, techniques were developed within CATIA using polygon reduction tools to reduce model size, while retaining surface detail at required user limits. This paper will discuss how these developments have played an essential part in facilitating EP2 remote handling task development and examine their impact during the EP2 shutdown.

Programmable System-on-Chip (PSoC) Embedded Readout Designs for Liquid Helium Level Sensors.

Science.gov (United States)

Parasakthi, C; Gireesan, K; Usha Rani, R; Sheela, O K; Janawadkar, M P

2014-08-01

This article reports the development of programmable system-on-chip (PSoC)-based embedded readout designs for liquid helium level sensors using resistive liquid vapor discriminators. The system has been built for the measurement of liquid helium level in a concave-bottomed, helmet-shaped, fiber-reinforced plastic cryostat for magnetoencephalography. This design incorporates three carbon resistors as cost-effective sensors, which are mounted at desired heights inside the cryostat and were used to infer the liquid helium level by measuring their temperature-dependent resistance. Localized electrical heating of the carbon resistors was used to discriminate whether the resistor is immersed in liquid helium or its vapor by exploiting the difference in the heat transfer rates in the two environments. This report describes a single PSoC chip for the design and development of a constant current source to drive the three carbon resistors, a multiplexer to route the sensor outputs to the analog-to-digital converter (ADC), a buffer to avoid loading of the sensors, an ADC for digitizing the data, and a display using liquid crystal display cum light-emitting diode modules. The level sensor readout designed with a single PSoC chip enables cost-effective and reliable measurement system design. © 2014 Society for Laboratory Automation and Screening.

Magnetotransport in a quasi-one-dimensional electron system over superfluid helium

International Nuclear Information System (INIS)

Nikolaenko, V.A.; Kovdrya, Yu.Z.; Gladchenko, S.P.

2002-01-01

Magnetotransport in a nondegenerate quasi-one-dimensional electron system (Q1D) over superfluid helium is investigated experimentally. The experiments were carried out at perpendicular magnetic fields, B xx of the conducting channels mainly grows with increasing B for both the electron-gas atom scattering (T > 0.9 K) and the electron-ripplon scattering (T c τ>1(here ω c is the cyclotron frequency and t is the relaxation time of the electron system) agree qualitatively with the self-consistent Born approximation theory for a 2D electron system over helium. It is supposed that the quantitative discrepancies in the experimental and theoretical data are connected with different peculiar features of the investigated and analyzed electron systems. The experimental data on electron mobility at low temperatures and small magnetic fields coincide with the theoretical calculation made for the Q1D system. The negative magnetoresistance of the channels observed both in the electron-gas scattering and electron-ripplon scattering regions is supposed to be due to weak localization of carriers in the investigated electron system

Experimental studies on helium release and stratification within the AIHMS facility

International Nuclear Information System (INIS)

Prabhakar, Aneesh; Agrawal, Nilesh; Raghavan, V.; Das, Sarit K.

2015-01-01

Hydrogen is generated during core meltdown accidents in nuclear power plants. The study of hydrogen release and mixing within the containment is an important area of safety research. An experimental setup called the AERB-IIT Madras Hydrogen Mixing Studies (AIHMS) facility is setup at IIT Madras to study the distribution of helium (an inert surrogate to hydrogen) subsequent to release as a jet. The present paper gives details of the design, fabrication and instrumentation of the AIHMS facility. It then compares the features of the facility with respect to other facilities existing for hydrogen mitigation studies. Then it gives details of the experiments on concentration build-up studies as a result of injection of gases (air and helium) performed in this experimental facility. (author)

Helium leak and chemical impurities control technology in HTTR

International Nuclear Information System (INIS)

Tochio, Daisuke; Shimizu, Atsushi; Hamamoto, Shimpei; Sakaba, Nariaki

2014-01-01

Japan Atomic Energy Agency (JAEA) has designed and developed high-temperature gas-cooled reactor (HTGR) hydrogen cogeneration system named gas turbine high-temperature reactor (GTHTR300C) as a commercial HTGR. Helium gas is used as the primary coolant in HTGR. Helium gas is easy to leak, and the primary helium leakage should be controlled tightly from the viewpoint of preventing the release of radioactive materials to the environment. Moreover from the viewpoint of preventing the oxidization of graphite and metallic material, the helium coolant chemistry should be controlled tightly. The primary helium leakage and the helium coolant chemistry during the operation is the major factor in the HTGR for commercialization of HTGR system. This paper shows the design concept and the obtained operational experience on the primary helium leakage control and primary helium impurity control in the high-temperature engineering test reactor (HTTR) of JAEA. Moreover, the future plan to obtain operational experience of these controls for commercialization of HTGR system is shown. (author)

Numerical study of the influence of dielectric tube on propagation of atmospheric pressure plasma jet based on coplanar dielectric barrier discharge

Science.gov (United States)

Haixin, HU; Feng, HE; Ping, ZHU; Jiting, OUYANG

2018-05-01

A 2D fluid model was employed to simulate the influence of dielectric on the propagation of atmospheric pressure helium plasma jet based on coplanar dielectric barrier discharge (DBD). The spatio-temporal distributions of electron density, ionization rate, electrical field, spatial charge and the spatial structure were obtained for different dielectric tubes that limit the helium flow. The results show that the change of the relative permittivity of the dielectric tube where the plasma jet travels inside has no influence on the formation of DBD itself, but has great impact on the jet propagation. The velocity of the plasma jet changes drastically when the jet passes from a tube of higher permittivity to one of lower permittivity, resulting in an increase in jet length, ionization rate and electric field, as well as a change in the distribution of space charges and discharge states. The radius of the dielectric tube has a great influence on the ring-shaped or solid bullet structure. These results can well explain the behavior of the plasma jet from the dielectric tube into the ambient air and the hollow bullet in experiments.

Surface electrons of helium films

International Nuclear Information System (INIS)

Studart, N.; Hipolito, O.

1986-01-01

Theoretical calculations of some properties of two-dimensional electrons on a liquid helium film adsorbed on a solid substrate are reviewed. We describe the spectrum of electron bound states on bulk helium as well on helium films. The correlational properties, such as the structure factor and correlation energy, are determined as functions of the film thickness for different types of substrates in the framework of a Generalized Random-Phase Approximation. The collective excitations of this system are also described. The results for electrons on the surface of thin films and bulk helium are easily obtained. we examine the electron interaction with the excitations of the liquid helium surface resulting in a new polaron state, which was observed very recently. The ground state energy and the effective mass of this polaron are determined by using the path-integral formalism and unitary-transformation method. Recent speculations about the phase diagram of electrons on the helium film are also discussed. (Author) [pt

High-temperature helium-loop facility

International Nuclear Information System (INIS)

Tokarz, R.D.

1981-09-01

The high-temperature helium loop is a facility for materials testing in ultrapure helium gas at high temperatures. The closed loop system is capable of recirculating high-purity helium or helium with controlled impurities. The gas loop maximum operating conditions are as follows: 300 psi pressure, 500 lb/h flow rate, and 2100 0 F temperature. The two test sections can accept samples up to 3.5 in. diameter and 5 ft long. The gas loop is fully instrumented to continuously monitor all parameters of loop operation as well as helium impurities. The loop is fully automated to operate continuously and requires only a daily servicing by a qualified operator to replenish recorder charts and helium makeup gas. Because of its versatility and high degree of parameter control, the helium loop is applicable to many types of materials research. This report describes the test apparatus, operating parameters, peripheral systems, and instrumentation system. The experimental capabilities and test conand presents the results that have been obtained. The study has been conducted using a four-phase approach. The first phase develops the solution to the steady-state radon-diffusion equation in one-dimensieered barriers; disposal charge analysis; analysis of spent fuel policy implementation; spent f water. Field measurements and observations are reported for each site. Analytical data and field measurements are presented in tables and maps. Uranium concentrations in the sediments which were above detection limits ranged from 0.10 t 51.2 ppM. The mean of the logarithms of the uranium concentrations was 0.53. A group of high uranium concentrations occurs near the junctions of quadrangles AB, AC, BB, a 200 mK. In case 2), x-ray studies of isotopic phase separation in 3 He-- 4 He bcc solids were carried out by B. A. Fraass

Stationary Population Inversion in an Expanding Argon Plasma Jet by Helium Puffing

National Research Council Canada - National Science Library

Akatsuka, H; Kano, K

2005-01-01

... out. Population inversion between Ar I excited states 5s'->4p'[1/2]1 and 5s'->4p[3/2]1,2, [5/2]2,3 is created by helium gas-contact cooling of electrons, whereas it is not created without gas-contact. Ar I lines 1.14 m, 1.34 m...

Hydrogen extraction from liquid lithium-lead alloy by bubbling with rotational jet nozzle

International Nuclear Information System (INIS)

Xie Bo; Yang Tongzai; Guan Rui; Weng Kuiping

2010-01-01

The technology of tritium extraction from lithium-lead alloy has been simulated, hydrogen extraction from lithium-lead alloy by bubbling with rotational jet nozzle being used to simulate tritium in the study based on the introduction of fluid dynamics to establish algebraic model. The results show that the higher than lithium-lead melting temperature, the higher cumulative hydrogen extraction efficiency, and gas holdup of bubble column is little affected by the impeller diameter. Gas holdup when using small aperture is slightly higher when using large aperture only at a high helium flow rate, but the smaller the aperture, the greater the bubble surface area, and a marked increase in intensity of flow circulation for liquid lithium-lead with the increase of helium flow rate, hydrogen extraction rate increases too. Moreover, influence of the jet rotational velocity on hydrogen extraction is limited. (authors)

A numerical model for diffusion of helium in a hydrogen plasma

International Nuclear Information System (INIS)

Potters, J.H.H.M.

1983-07-01

A quasi-cylindrical steady-state numerical model for the diffusion of helium in a hydrogen plasma is presented, adopting collisional plus either ALCATOR-INTOR- or ASDEX-like anomalous transport for the charged species. The coupled momentum and conservation equations for H + , He + and He ++ are solved to obtain radial profiles of their densities, consistent with those of the neutral species. For the neutrals, a diffusion equation is used for the transport of H, whereas He is assumed to enter the plasma with an energy equal to the temperature of the plasma immediately in front of the wall. A stable numerical scheme for the solution of the coupled ion and electron energy balances is discussed. Results are presented for the JET-tokamak, using prescribed temperature profiles. Collisional effects are shown to produce an enhancement of the alpha particle density about 10 centimetres in front of the wall, especially in combination with ALCATOR-INTOR-like scaling. The neutral helium density that accumulates in the outer plasma is too low to allow for pumping helium from a cool plasma/gas blanket

Cold atmospheric plasma jet in an axial DC electric field

Energy Technology Data Exchange (ETDEWEB)

Lin, Li, E-mail: lilin@gwu.edu, E-mail: keidar@gwu.edu; Keidar, Michael, E-mail: lilin@gwu.edu, E-mail: keidar@gwu.edu [Department of Mechanical and Aerospace Engineering, School of Engineering and Applied Science, The George Washington University, Washington, DC 20052 (United States)

2016-08-15

Cold atmospheric plasma (CAP) jet is currently intensively investigated as a tool for new and potentially transformative cancer treatment modality. However, there are still many unknowns about the jet behavior that requires attention. In this paper, a helium CAP jet is tested in an electrostatic field generated by a copper ring. Using Rayleigh microwave scattering method, some delays of the electron density peaks for different ring potentials are observed. Meanwhile, a similar phenomenon associated with the bullet velocity is found. Chemical species distribution along the jet is analyzed based on the jet optical emission spectra. The spectra indicate that a lower ring potential, i.e., lower DC background electric field, can increase the amount of excited N{sub 2}, N{sub 2}{sup +}, He, and O in the region before the ring, but can decrease the amount of excited NO and HO almost along the entire jet. Combining all the results above, we discovered that an extra DC potential mainly affects the temporal plasma jet properties. Also, it is possible to manipulate the chemical compositions of the jet using a ring with certain electric potentials.

Analysis of helium purification system capability during water ingress accident in RDE

Science.gov (United States)

Sriyono; Kusmastuti, Rahayu; Bakhri, Syaiful; Sunaryo, Geni Rina

2018-02-01

The water ingress accident caused by steam generator tube rupture (SGTR) in RDE (Experimental Power Reactor) must be anticipated. During the accident, steam from secondary system diffused and mixed with helium gas in the primary coolant. To avoid graphite corrosion in the core, steam will be removed by Helium purification system (HPS). There are two trains in HPS, first train for normal operation and the second for the regeneration and accident. The second train is responsible to clean the coolant during accident condition. The second train is equipped with additional component, i.e. water cooler, post accident blower, and water separator to remove this mixture gas. During water ingress, the water release from rupture tube is mixed with helium gas. The water cooler acts as a steam condenser, where the steam will be separated by water separator from the helium gas. This paper analyses capability of HPS during water ingress accident. The goal of the research is to determine the time consumed by HPS to remove the total amount of water ingress. The method used is modelling and simulation of the HPS by using ChemCAD software. The BDBA and DBA scenarios will be simulated. In BDBA scenario, up to 110 kg of water is assumed to infiltrate to primary coolant while DBA is up to 35 kg. By using ChemCAD simulation, the second train will purify steam ingress maximum in 0.5 hours. The HPS of RDE has a capability to anticipate the water ingress accident.

Asteroseismic estimate of helium abundance of a solar analog binary system

Energy Technology Data Exchange (ETDEWEB)

Verma, Kuldeep; Antia, H. M. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Faria, João P.; Monteiro, Mário J. P. F. G. [Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Basu, Sarbani [Astronomy Department, Yale University, P. O. Box 208101, New Haven, CT 065208101 (United States); Mazumdar, Anwesh [Homi Bhabha Centre for Science Education, TIFR, V. N. Purav Marg, Mankhurd, Mumbai 400088 (India); Appourchaux, Thierry [Institut d' Astrophysique Spatiale, Université Paris XI-CNRS (UMR8617), Batiment 121, F-91405 Orsay Cedex (France); Chaplin, William J. [School of Physics and Astronomy, University of Birmingham, B15 2TT (United Kingdom); García, Rafael A. [Laboratoire AIM, CEA/DSM, CNRS, Université Paris Diderot, IRFU/SAp, Centre de Saclay, F-91191 Gif-sur-Yvette Cedex (France); Metcalfe, Travis S. [Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark)

2014-08-01

16 Cyg A and B are among the brightest stars observed by Kepler. What makes these stars more interesting is that they are solar analogs. 16 Cyg A and B exhibit solar-like oscillations. In this work we use oscillation frequencies obtained using 2.5 yr of Kepler data to determine the current helium abundance of these stars. For this we use the fact that the helium ionization zone leaves a signature on the oscillation frequencies and that this signature can be calibrated to determine the helium abundance of that layer. By calibrating the signature of the helium ionization zone against models of known helium abundance, the helium abundance in the envelope of 16 Cyg A is found to lie in the range of 0.231 to 0.251 and that of 16 Cyg B lies in the range of 0.218 to 0.266.

Closed-loop helium circulation system for actuation of a continuously operating heart catheter pump.

Science.gov (United States)

Karabegovic, Alen; Hinteregger, Markus; Janeczek, Christoph; Mohl, Werner; Gföhler, Margit

2017-06-09

Currently available, pneumatic-based medical devices are operated using closed-loop pulsatile or open continuous systems. Medical devices utilizing gases with a low atomic number in a continuous closed loop stream have not been documented to date. This work presents the construction of a portable helium circulation addressing the need for actuating a novel, pneumatically operated catheter pump. The design of its control system puts emphasis on the performance, safety and low running cost of the catheter pump. Static and dynamic characteristics of individual elements in the circulation are analyzed to ensure a proper operation of the system. The pneumatic circulation maximizes the working range of the drive unit inside the catheter pump while reducing the total size and noise production.Separate flow and pressure controllers position the turbine's working point into the stable region of the pressure creation element. A subsystem for rapid gas evacuation significantly decreases the duration of helium removal after a leak, reaching subatmospheric pressure in the intracorporeal catheter within several milliseconds. The system presented in the study offers an easy control of helium mass flow while ensuring stable behavior of its internal components.

Gas jet studies towards an optimization of the IGISOL LIST method

CERN Document Server

Reponen, M; Kurpeta, J; Sonnenschein, V; Pohjalainen, I; Aysto, J; Kessler, T; Piszczek, S; Karvonen, P; Marsh, B

2011-01-01

Gas jets emitted from an ion guide have been studied as a function of nozzle type and gas cell-to-background pressure ratio in order to obtain a low divergent, uniform jet over a distance of several cm. The jet has been probed by imaging the light emitted from excited argon or helium gas atoms. For a simple exit hole or converging-diverging nozzle, the jet diameter was found to be insensitive to the nozzle shape and inlet pressure. Sonic jets with a FWHM below 6 mm were achieved with a background pressure larger than 1 mbar in the expansion chamber. The measurements are supported by the detection of radioactive (219)Rn recoils from an alpha recoil source mounted within the gas cell. A Laval nozzle produced a well-collimated supersonic jet at low background pressures with a FWHM of similar to 6 mm over a distance of 14 cm. Direct Pitot probe measurements, on-axis, revealed a non-uniform pressure distribution in the gas jet of the Laval nozzle, supporting the visual observations. All measurements are motivated ...

Aerial Deployment and Inflation System for Mars Helium Balloons

Science.gov (United States)

Lachenmeler, Tim; Fairbrother, Debora; Shreves, Chris; Hall, Jeffery, L.; Kerzhanovich, Viktor V.; Pauken, Michael T.; Walsh, Gerald J.; White, Christopher V.

2009-01-01

A method is examined for safely deploying and inflating helium balloons for missions at Mars. The key for making it possible to deploy balloons that are light enough to be buoyant in the thin, Martian atmosphere is to mitigate the transient forces on the balloon that might tear it. A fully inflated Mars balloon has a diameter of 10 m, so it must be folded up for the trip to Mars, unfolded upon arrival, and then inflated with helium gas in the atmosphere. Safe entry into the Martian atmosphere requires the use of an aeroshell vehicle, which protects against severe heating and pressure loads associated with the hypersonic entry flight. Drag decelerates the aeroshell to supersonic speeds, then two parachutes deploy to slow the vehicle down to the needed safe speed of 25 to 35 m/s for balloon deployment. The parachute system descent dynamic pressure must be approximately 5 Pa or lower at an altitude of 4 km or more above the surface.

20 K Helium Refrigeration System for NASA-JSC Chamber-A

Science.gov (United States)

Homan, J.; Redman, R.; Ganni, V.; Sidi-Yekhelef, A.; Knudsen, P.; Norton, R.; Lauterbach, J.; Linza, R.; Vargas, G.

2013-01-01

A new 20 K helium refrigerator installed at NASA Johnson Space Center's Space Environment Simulation Laboratory (SESL) was successfully commissioned and tested in 2012. The refrigerator is used to create a deep space environment within SESL s Chamber A to perform ground testing of the James Webb Space Telescope. The chamber previously and currently still has helium cryopumping panels (CPP) and LN2 shrouds used to create Low Earth Orbit environments. Now with the new refrigerator and new helium shrouds (45 x 65 ) the chamber can create a deep space environment. The process design, system analysis, specification development, and commissioning oversight were performed by the cryogenics department at Jefferson Labs, while the contracts and system installation was performed by the ESC group at JSC. Commissioning data indicate a inverse coefficient of performance better than 70 W/W for a 18 KW load at 20 K (accounting for liquid nitrogen precooling power) that remains essentially constant down to 1/3 of this load. Even at 10 percent of the maximum capacity, the performance is better than 140 W/W at 20K. The refrigerator exceeded all design goals and demonstrated the ability to support a wide load range from 10kW at 15 K to 100 kW at 100K. The refrigerator is capable of operating at any load temperature from 15K to ambient with tight temperature stability. The new shroud (36 tons of aluminum) can be cooled from room temperature to 20 K in 24 hours. This paper will outline the process design and commissioning results.

Mathematical Model of the Jet Engine Fuel System

Directory of Open Access Journals (Sweden)

Klimko Marek

2015-01-01

Full Text Available The paper discusses the design of a simplified mathematical model of the jet (turbo-compressor engine fuel system. The solution will be based on the regulation law, where the control parameter is a fuel mass flow rate and the regulated parameter is the rotational speed. A differential equation of the jet engine and also differential equations of other fuel system components (fuel pump, throttle valve, pressure regulator will be described, with respect to advanced predetermined simplifications.

Mathematical Model of the Jet Engine Fuel System

Science.gov (United States)

Klimko, Marek

2015-05-01

The paper discusses the design of a simplified mathematical model of the jet (turbo-compressor) engine fuel system. The solution will be based on the regulation law, where the control parameter is a fuel mass flow rate and the regulated parameter is the rotational speed. A differential equation of the jet engine and also differential equations of other fuel system components (fuel pump, throttle valve, pressure regulator) will be described, with respect to advanced predetermined simplifications.

CFD Analysis on the Passive Heat Removal by Helium and Air in the Canister of Spent Fuel Dry Storage System

Energy Technology Data Exchange (ETDEWEB)

Shin, Do Young; Jeong, Ui Ju; Kim, Sung Joong [Hanyang University, Seoul (Korea, Republic of)

2016-05-15

In the current commercial design, the canister of the dry storage system is mainly backfilled with helium gas. Helium gas shows very conductive behavior due to high thermal conductivity and small density change with temperature. However, other gases such as air, argon, or nitrogen are expected to show effective convective behavior. Thus these are also considered as candidates for the backfill gas to provide effective coolability. In this study, to compare the dominant cooling mechanism and effectiveness of cooling between helium gas and air, a computational fluid dynamics (CFD) analysis for the canister of spent fuel dry storage system with backfill gas of helium and air is carried out. In this study, CFD simulations for the helium and air backfilled gas for dry storage system canister were carried out using ANSYS FLUENT code. For the comparison work, two backfilled fluids were modeled with same initial and boundary conditions. The observed major difference can be summarized as follows. - The simulation results showed the difference in dominant heat removal mechanism. Conduction for helium, and convection for air considering Reynolds number distribution. - The temperature gradient inside the fuel assembly showed that in case of air, more effective heat mixing occurred compared to helium.

Design of helium-gas supplying facility of out-of-pile demonstration test for HTTR heat utilization system

Energy Technology Data Exchange (ETDEWEB)

Hino, Ryutaro; Fujisaki, Katsuo; Kobayashi, Toshiaki [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment] [and others

1996-09-01

One of the objectives of the High-Temperature Engineering Test Reactor (HTTR) is to demonstrate effectiveness of high-temperature heat utilization. Prior to connect a heat utilization system to the HTTR, a series of out-of-pile demonstration test is indispensable to improve components` performance, to demonstrate operation, control and safety technologies and to verify analysis codes for design and safety evaluation. After critical review and discussion on the out-of-pile demonstration test, a test facility have been designed. In this report, a helium-gas supplying facility simulated the HTTR system was described in detail, which supplies High-temperature helium-gas of 900degC to a steam reforming facility mocking-up the HTTR heat utilization system. Components of the Helium Engineering Demonstration Loop (HENDEL) were selected to reuse in the helium-gas supplying facility in order to decrease construction cost. Structures and specifications of new components such as a high-temperature heater and a preheater were decided after evaluation of thermal and hydraulic performance and strength. (author)

Correlated wave functions for three-particle systems with Coulomb interaction - The muonic helium atom

Science.gov (United States)

Huang, K.-N.

1977-01-01

A computational procedure for calculating correlated wave functions is proposed for three-particle systems interacting through Coulomb forces. Calculations are carried out for the muonic helium atom. Variational wave functions which explicitly contain interparticle coordinates are presented for the ground and excited states. General Hylleraas-type trial functions are used as the basis for the correlated wave functions. Excited-state energies of the muonic helium atom computed from 1- and 35-term wave functions are listed for four states.

Measurement of helium production cross sections of iron for d-T neutrons by helium accumulation method

Energy Technology Data Exchange (ETDEWEB)

Takao, Yoshiyuki; Kanda, Yukinori; Nagae, Koji; Fujimoto, Toshihiro [Kyushu Univ., Fukuoka (Japan); Ikeda, Yujiro

1997-03-01

Helium production cross sections of Iron were measured by helium accumulation method for neutron energies from 13.5 to 14.9 MeV. Iron samples were irradiated with FNS, an intense d-T neutron source of JAERI. As the neutron energy varies according to the emission angle at the neutron source, the samples were set around the neutron source and were irradiated by neutrons of different energy depending on each sample position. The amount of helium produced in a sample was measured by Helium Atoms Measurement System at Kyushu University. The results of this work are in good agreement with other experimental data in the literature and also compared with the evaluated values in JENDL-3. (author)

The JET high temperature in-vessel inspection system

International Nuclear Information System (INIS)

Businaro, T.; Cusack, R.; Calbiati, L.; Raimondi, T.

1989-01-01

The JET In-vessel Inspection System (IVIS) has been enhanced for operation under the following nominal conditions: vacuum vessel at 350 degC; vacuum vessel evacuated (∼10 -9 mbar); radiation dose during D-T phase 10 rads. The target resolution of the pictures is 2 mm at 5 m distance and tests on radiation resistance of the IVIS system are being carried out. Since June 1988, the new system is installed in the JET machine and the first inspections of the intire vessel at 250 degC have been satisfactory done. (author). 3 refs.; 6 figs.; 1 tab

Helium turbomachine design for GT-MHR power plant

International Nuclear Information System (INIS)

McDonald, C.F.; Orlando, R.J.

1994-07-01

The power conversion system in the gas turbine modular helium reactor (GT-MHR) power plant is based on a highly recuperated closed Brayton cycle. The major component in the direct cycle system is a helium closed-cycle gas turbine rated at 286 MW(e). The rotating group consists of an intercooled helium turbocompressor coupled to a synchronous generator. The vertical rotating assembly is installed in a steel vessel, together with the other major components (i.e., recuperator, precooler, intercooler, and connecting ducts and support structures). The rotor is supported on an active magnetic bearing system. The turbine operates directly on the reactor helium coolant, and with a temperature of 850 degree C (1562 degree F) the plant efficiency is over 47%. This paper addresses the design and development planning of the helium turbomachine, and emphasizes that with the utilization of proven technology, this second generation nuclear power plant could be in service in the first decade of the 21st century

Optomechanics in a Levitated Droplet of Superfluid Helium

Science.gov (United States)

Brown, Charles; Harris, Glen; Harris, Jack

2017-04-01

A critical issue common to all optomechanical systems is dissipative coupling to the environment, which limits the system's quantum coherence. Superfluid helium's extremely low optical and mechanical dissipation, as well as its high thermal conductivity and its ability cool itself via evaporation, makes the mostly uncharted territory of superfluid optomechanics an exciting avenue for exploring quantum effects in macroscopic objects. I will describe ongoing work that aims to exploit the unique properties of superfluid helium by constructing an optomechanical system consisting of a magnetically levitated droplet of superfluid helium., The optical whispering gallery modes (WGMs) of the droplet, as well as the mechanical oscillations of its surface, should offer exceptionally low dissipation, and should couple to each other via the usual optomechanical interactions. I will present recent progress towards this goal, and also discuss the background for this work, which includes prior demonstrations of magnetic levitation of superfluid helium, high finesse WGMs in liquid drops, and the self-cooling of helium drops in vacuum.

Decontamination using the high-pressure wet jet system

International Nuclear Information System (INIS)

Brandt, D.

1985-01-01

For decontaminating machine components, tools, instruments and scrap in nuclear plants the most varying decontamination procedures are used. At the nuclear power plant Wuergassen a mobile high-pressure wet jet unit, developed by Ernst Schmutz GmbH, was successfully used for the first time in extensive decontamination work. The recycling system integrated in the decontamination unit substantially reduces secondary waste, which is usually produced in large quantities by the dry jet method, and continually extracts the contaminated dirt thus guaranteeing full utilisation of the jet agent while preventing secondary contamination of the components to be treated. (orig.) [de

Forced two phase helium cooling of large superconducting magnets

International Nuclear Information System (INIS)

Green, M.A.; Burns, W.A.; Taylor, J.D.

1979-08-01

A major problem shared by all large superconducting magnets is the cryogenic cooling system. Most large magnets are cooled by some variation of the helium bath. Helium bath cooling becomes more and more troublesome as the size of the magnet grows and as geometric constraints come into play. An alternative approach to cooling large magnet systems is the forced flow, two phase helium system. The advantages of two phase cooling in many magnet systems are shown. The design of a two phase helium system, with its control dewar, is presented. The paper discusses pressure drop of a two phase system, stability of a two phase system and the method of cool down of a two phase system. The results of experimental measurements at LBL are discussed. Included are the results of cool down and operation of superconducting solenoids

Maintenance of the JET active gas handling system

International Nuclear Information System (INIS)

Brennan, P.D.; Bell, A.C.; Brown, K.; Cole, C.; Cooper, B.; Gibbons, C.; Harris, M.; Jones, G.; Knipe, S.; Lewis, J.; Manning, C.; Miller, A.; Perevezentsev, A.; Skinner, N.; Stagg, R.; Stead, M.; Thomas, R.; Yorkshades, J.

2003-01-01

The JET active gas handling system (AGHS) has been in operation in conjunction with the JET machine since Spring 1997. The tritium levels within the vessel have remained sufficiently high, 6.2 g at the end of the DTE1 experiment and currently 1.5 g, such that the AGHS has been required to operate continuously to detritiate gases liberated during D-D operations and to maintain discharges to the environment to ALARP. Maintaining the system to ensure continued operation has been a key factor in guaranteeing the continued availability of the essential sub-systems. The operational history of the JET AGHS has been previously documented in a number of papers [R. Laesser, et al. Proc. of the 19th SOFT Conf. 1 (1996) 227; R. Laesser, et al., Fusion Eng. Des. 46 (1999) 307; P.D. Brennan, et al., 18th Symp. on Fusion Eng., 1999]. Operational downtime is minimised through well-engineered sub-systems that use high integrity components. Outage, contamination and operator dosage are minimised through pre-planned and prepared maintenance operations. The reliability of sub-system critical condition fault detection is demonstrated through routine testing of hard-wired alarms and interlocks

The Use of Compressed Air for Micro-Jet Cooling After MIG Welding

Directory of Open Access Journals (Sweden)

Hadryś D.

2016-09-01

Full Text Available The material selected for this investigation was low alloy steel weld metal deposit (WMD after MIG welding with micro-jet cooling. The present investigation was aimed as the following tasks: obtained WMD with various amount of acicular ferrite and further analyze impact toughness of WMD in terms of acicular ferrite amount in it. Weld metal deposit (WMD was first time carried out for MIG welding with micro-jet cooling of compressed air and gas mixture of argon and air. Until that moment only argon, helium and nitrogen were tested as micro-jet gases for MIG/MAG processes. An important role in the interpretation of the results can give methods of artificial intelligence.

Implications of Upwells as Hydrodynamic Jets in a Pulse Jet Mixed System

Energy Technology Data Exchange (ETDEWEB)

Pease, Leonard F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bamberger, Judith A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Minette, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2015-08-01

This report evaluates the physics of the upwell flow in pulse jet mixed systems in the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Although the initial downward flow and radial flow from pulse jet mixers (PJMs) has been analyzed in some detail, the upwells have received considerably less attention despite having significant implications for vessel mixing. Do the upwells behave like jets? How do the upwells scale? When will the central upwell breakthrough? What proportion of the vessel is blended by the upwells themselves? Indeed, how the physics of the central upwell is affected by multiple PJMs (e.g., six in the proposed mixing vessels), non-Newtonian rheology, and significant multicomponent solids loadings remain unexplored. The central upwell must satisfy several criteria to be considered a free jet. First, it must travel for several diameters in a nearly constant direction. Second, its velocity must decay with the inverse of elevation. Third, it should have an approximately Gaussian profile. Fourth, the influence of surface or body forces must be negligible. A combination of historical data in a 12.75 ft test vessel, newly analyzed data from the 8 ft test vessel, and conservation of momentum arguments derived specifically for PJM operating conditions demonstrate that the central upwell satisfies these criteria where vigorous breakthrough is achieved. An essential feature of scaling from one vessel to the next is the requirement that the underlying physics does not change adversely. One may have confidence in scaling if (1) correlations and formulas capture the relevant physics; (2) the underlying physics does not change from the conditions under which it was developed to the conditions of interest; (3) all factors relevant to scaling have been incorporated, including flow, material, and geometric considerations; and (4) the uncertainty in the relationships is sufficiently narrow to meet required specifications. Although the central upwell

Time-resolved Thomson scattering on high-intensity laser-produced hot dense helium plasmas

International Nuclear Information System (INIS)

Sperling, P; Liseykina, T; Bauer, D; Redmer, R

2013-01-01

The introduction of brilliant free-electron lasers enables new pump–probe experiments to characterize warm and hot dense matter states, i.e. systems at solid-like densities and temperatures of one to several hundred eV. Such extreme conditions are relevant for high-energy density studies such as, e.g., in planetary physics and inertial confinement fusion. We consider here a liquid helium jet pumped with a high-intensity optical short-pulse laser that is subsequently probed with brilliant soft x-ray radiation. The optical short-pulse laser generates a strongly inhomogeneous helium plasma which is characterized with particle-in-cell simulations. We derive the respective Thomson scattering spectrum based on the Born–Mermin approximation for the dynamic structure factor considering the full density and temperature-dependent Thomson scattering cross section throughout the target. We observe plasmon modes that are generated in the interior of the target and study their temporal evolution. Such pump–probe experiments are promising tools to measure the important plasma parameters density and temperature. The method described here can be applied to various pump–probe scenarios by combining optical lasers, soft x-rays and hard x-ray sources. (paper)

New data storage and retrieval systems for JET data

Energy Technology Data Exchange (ETDEWEB)

Layne, Richard E-mail: richard.layne@ukaea.org.uk; Wheatley, Martin E-mail: martin.wheatley@ukaea.org.uk

2002-06-01

Since the start of the Joint European Torus (JET), an IBM mainframe has been the main platform for data analysis and storage (J. Comput. Phys. 73 (1987) 85). The mainframe was removed in June 2001 and Solaris and Linux are now the main data storage and analysis platforms. New data storage and retrieval systems have therefore been developed: the Data Warehouse, the JET pulse file server, and the processed pulse file system. In this paper, the new systems will be described, and the design decisions that led to the final systems will be outlined.

New data storage and retrieval systems for JET data

International Nuclear Information System (INIS)

Layne, Richard; Wheatley, Martin

2002-01-01

Since the start of the Joint European Torus (JET), an IBM mainframe has been the main platform for data analysis and storage (J. Comput. Phys. 73 (1987) 85). The mainframe was removed in June 2001 and Solaris and Linux are now the main data storage and analysis platforms. New data storage and retrieval systems have therefore been developed: the Data Warehouse, the JET pulse file server, and the processed pulse file system. In this paper, the new systems will be described, and the design decisions that led to the final systems will be outlined

Considerations on the design of a helium circulator for a high temperature modular reactor system

International Nuclear Information System (INIS)

Dumm, K.; Donaldson, J.

1988-01-01

A modular helium cooled, high temperature reactor system with a thermal output of 200 MW per reactor has been developed by the KWU group for cogeneration of electricity and process steam. The flow of the reactor coolant - Helium at 60 bars and 250/700 deg. C is maintained by one circulator per reactor. The circulator is driven by a variable speed Siemens asynchronous motor and is submerged in the helium primary system. For operational reasons high reliability and availability of the circulator is required. The operational requirements for the circulator design are presented in this paper. The actual design has been carried out in close cooperation with the designer and manufacturer of all submerged circulators operating in AGR plants in Great Britain, James Howden Co. Renfrew, Scotland. Design solutions received so far and mainly based on sufficiently proven components - such as oil bath lubricated bearing systems - will be described. Special attention will be paid on the necessary test work; especially for the prototype to confirm the lay out. (author). 9 figs

Capacity enhancement of indigenous expansion engine based helium liquefier

Science.gov (United States)

Doohan, R. S.; Kush, P. K.; Maheshwari, G.

2017-02-01

Development of technology and understanding for large capacity helium refrigeration and liquefaction at helium temperature is indispensable for coming-up projects. A new version of helium liquefier designed and built to provide approximately 35 liters of liquid helium per hour. The refrigeration capacity of this reciprocating type expansion engine machine has been increased from its predecessor version with continuous improvement and deficiency debugging. The helium liquefier has been built using components by local industries including cryogenic Aluminum plate fin heat exchangers. Two compressors with nearly identical capacity have been deployed for the operation of system. Together they consume about 110 kW of electric power. The system employs liquid Nitrogen precooling to enhance liquid Helium yield. This paper describes details of the cryogenic expander design improvements, reconfiguration of heat exchangers, performance simulation and their experimental validation.

Plasma bullet current measurements in a free-stream helium capillary jet

Science.gov (United States)

Oh, Jun-Seok; Walsh, James L.; Bradley, James W.

2012-06-01

A commercial current monitor has been used to measure the current associated with plasma bullets created in both the positive and negative half cycles of the sinusoidal driving voltage sustaining a plasma jet. The maximum values of the positive bullet current are typically ˜750 µA and persist for 10 µs, while the peaks in the negative current of several hundred μA are broad, persisting for about 40 µs. From the time delay of the current peaks with increasing distance from the jet nozzle, an average bullet propagation speed has been measured; the positive and negative bullets travel at 17.5 km s-1 and 3.9 km s-1 respectively. The net space charge associated with the bullet(s) has also been calculated; the positive and negative bullets contain a similar net charge of the order of 10-9 C measured at all monitor positions, with estimated charged particle densities nb of ˜1010-1011 cm-3 in the bullet.

Separation of compressor oil from helium

International Nuclear Information System (INIS)

Strauss, R.; Perrotta, K.A.

1982-01-01

Compression of helium by an oil-sealed rorary screw compressor entrains as much as 4000 parts per million by weight of liquid and vapor oil impurities in the gas. The reduction below about 0.1 ppm for cryogenic applications is discussed. Oil seperation equipment designed for compressed air must be modified significantly to produce the desired results with helium. The main differences between air and helium filtration are described. A description of the coalescers is given with the continuous coalescing of liquid mist from air or other gas illustrated. Oil vapor in helium is discussed in terms of typical compressor oils, experimental procedure for measuring oil vapor concentration, measured volatile hydrocarbons in the lubricants, and calculated concentration of oil vapor in Helium. Liquid oil contamination in helium gas can be reduced well below 0.1 ppm by a properly designed multiple state coalescing filter system containing graded efficiency filter elements. The oil vapor problem is best attached by efficiently treating the oil to remove most of the colatiles before charging the compressor

Development test procedure High Pressure Water Jet System

International Nuclear Information System (INIS)

Crystal, J.B.

1995-01-01

Development testing will be performed on the water jet cleaning fixture to determine the most effective arrangement of water jet nozzles to remove contamination from the surfaces of canisters and other debris. The following debris may be stained with dye to simulate surface contaminates: Mark O, Mark I, and Mark II Fuel Storage Canisters (both stainless steel and aluminum), pipe of various size, (steel, stainless, carbon steel and aluminum). Carbon steel and stainless steel plate, channel, angle, I-beam and other surfaces, specifically based on the Scientific Ecology Group (SEG) inventory and observations of debris within the basin. Test procedure for developmental testing of High Pressure Water Jet System

Measurement of ozone production scaling in a helium plasma jet with oxygen admixture

Science.gov (United States)

Sands, Brian; Ganguly, Biswa

2012-10-01

Capillary dielectric barrier plasma jet devices that generate confined streamer-like discharges along a rare gas flow can produce significant quantities of reactive oxygen species with average input powers ranging from 100 mW to >1 W. We have measured spatially-resolved ozone production in a He plasma jet with O2 admixture concentrations up to 5% using absorption spectroscopy of the O3 Hartley band system. A 20-ns risetime, 10-13 kV positive unipolar voltage pulse train was used to power the discharge, with pulse repetition rates varied from 1-20 kHz. The discharge was operated in a transient glow mode to scale the input power by adjusting the gap width between the anode and downstream cathodic plane. Peak ozone number densities in the range of 10^16 - 10^17 cm-3 were measured. At a given voltage, the density of ozone increased monotonically up to 3% O2 admixture (6 mm gap) as the peak discharge current decreased by an order of magnitude. Ozone production increased with distance from the capillary, consistent with observations by other groups. Atomic oxygen production inferred from O-atom 777 nm emission intensity did not scale with ozone as the input power was increased. The spatial distribution of ozone and scaling with input power will be presented.

Exergy Analysis of the Cryogenic Helium Distribution System for the Large Hadron Collider (LHC)

CERN Document Server

Claudet, S; Tavian, L; Wagner, U

2010-01-01

The Large Hadron Collider (LHC) at CERN features the world’s largest helium cryogenic system, spreading over the 26.7 km circumference of the superconducting accelerator. With a total equivalent capacity of 145 kW at 4.5 K including 18 kW at 1.8 K, the LHC refrigerators produce an unprecedented exergetic load, which must be distributed efficiently to the magnets in the tunnel over the 3.3 km length of each of the eight independent sectors of the machine. We recall the main features of the LHC cryogenic helium distribution system at different temperature levels and present its exergy analysis, thus enabling to qualify second-principle efficiency and identify main remaining sources of irreversibility..

EXERGY ANALYSIS OF THE CRYOGENIC HELIUM DISTRIBUTION SYSTEM FOR THE LARGE HADRON COLLIDER (LHC)

International Nuclear Information System (INIS)

Claudet, S.; Lebrun, Ph.; Tavian, L.; Wagner, U.

2010-01-01

The Large Hadron Collider (LHC) at CERN features the world's largest helium cryogenic system, spreading over the 26.7 km circumference of the superconducting accelerator. With a total equivalent capacity of 145 kW at 4.5 K including 18 kW at 1.8 K, the LHC refrigerators produce an unprecedented exergetic load, which must be distributed efficiently to the magnets in the tunnel over the 3.3 km length of each of the eight independent sectors of the machine. We recall the main features of the LHC cryogenic helium distribution system at different temperature levels and present its exergy analysis, thus enabling to qualify second-principle efficiency and identify main remaining sources of irreversibility.

Reduction and degradation of amyloid aggregates by a pulsed radio-frequency cold atmospheric plasma jet

International Nuclear Information System (INIS)

Bayliss, D L; Walsh, J L; Iza, F; Kong, M G; Shama, G

2009-01-01

Surface-borne amyloid aggregates with mature fibrils are used as a non-infectious prion model to evaluate cold atmospheric plasmas (CAPs) as a prion inactivation strategy. Using a helium-oxygen CAP jet with pulsed radio-frequency (RF) excitation, amyloid aggregates deposited on freshly cleaved mica discs are reduced substantially leaving only a few spherical fragments of sub-micrometer sizes in areas directly treated by the CAP jet. Outside the light-emitting part of the CAP jet, plasma treatment results in a 'skeleton' of much reduced amyloid stacks with clear evidence of fibril fragmentation. Analysis of possible plasma species and the physical configuration of the jet-sample interaction suggests that the skeleton structures observed are unlikely to have arisen as a result of physical forces of detachment, but instead by progressive diffusion of oxidizing plasma species into porous amyloid aggregates. Composition of chemical bonds of this reduced amyloid sample is very different from that of intact amyloid aggregates. These suggest the possibility of on-site degradation by CAP treatment with little possibility of spreading contamination elsewhere , thus offering a new reaction chemistry route to protein infectivity control with desirable implications for the practical implementation of CAP-based sterilization systems.

PIP-II Cryogenic System and the evolution of Superfluid Helium Cryogenic Plant Specifications

Energy Technology Data Exchange (ETDEWEB)

Chakravarty, Anindya [Fermilab; Rane, Tejas [Fermilab; Klebaner, Arkadiy [Fermilab

2017-07-06

The PIP-II cryogenic system consists of a Superfluid Helium Cryogenic Plant (SHCP) and a Cryogenic Distribution System (CDS) connecting the SHCP to the Superconducting (SC) Linac consisting of 25 cryomodules. The dynamic heat load of the SC cavities for continuous wave (CW) as well as pulsed mode of operation has been listed out. The static heat loads of the cavities along with the CDS have also been discussed. Simulation study has been carried out to compute the supercritical helium (SHe) flow requirements for each cryomodule. Comparison between the flow requirements of the cryomodules for the CW and pulsed modes of operation have also been made. From the total computed heat load and pressure drop values in the CDS, the basic specifications for the SHCP, required for cooling the SC Linac, have evolved.

Implementation of a new Disruption Mitigation System into the control system of JET

Energy Technology Data Exchange (ETDEWEB)

Jachmich, Stefan, E-mail: s.jachmich@fz-juelich.de [Laboratory for Plasma Physics, Ecole Royale Militaire/Koninklijke Militaire School, B-1000 Brussels (Belgium); Kruezi, Uron; Card, Peter; Deakin, Kieron; Kinna, David [Culham Centre for Fusion Energy, Abingdon, Oxon OX14 3DB (United Kingdom); Koslowski, Hans Rudolf; Lambertz, Horst Toni [Forschungszentrum Jülich GmbH, IEK-4, 52425 Jülich (Germany); Lehnen, Michael [ITER Organization, Route de Vinon-sur-Verdon, CS90046, 13067 St Paul Lez Durance Cedex (France)

2015-10-15

Highlights: • A new Disruption Mitigation System based on Massive Gas Injection has been installed at JET. • The control of the attached gas handling system had to be integrated into the JET-operation. • An interlock system has been built to cope with the interaction of the DMS with other auxiliary systems. • The system has been commissioned and first example of DMS used to ameliorate a disruption are shown. - Abstract: A new Disruption Mitigation System (DMS) based on Massive Gas Injections (MGI) has been installed at the JET-tokamak. The key component of this system is a fast eddy current driven valve, which is capable of injecting up to 4.6 × 10{sup −3} MPa m{sup 3} in less than 5 ms. Along with this valve a new gas handling system has been installed, whose control had to be integrated into the JET-operation. The operation of the DMS requires interaction with several other systems. Although Massive Gas Injections are used to ameliorate potentially severe damage to the tokamak plant and plasma facing components caused by disruptions, they introduce a high risk for example to auxiliary heating systems or diagnostics, which could be damaged by high vacuum pressures. In addition to this, the presence of high pressure (of noble and flammable gases) in combination with high voltages represents a risk not only to the actual DMS plant itself (in case of a failure) but also to personnel in the vicinity. These varieties of risks have been addressed and are described in this article.

Turbulent viscosity and scale laws in turbulent jets with variable density; Viscosite turbulente et lois d`echelles dans les jets turbulents a masse volumique variable

Energy Technology Data Exchange (ETDEWEB)

Pietri, L.; Amielh, M.; Anselmet, F.; Fulachier, L. [Institut de Recherche sur les Phinomenes Hors Equilibre Equipe Turbulence, 13 - Marseille (France)

1997-12-31

Turbulent flows with strong density variations, like helium jets in the ambient air, have specific properties linked with the difference of gas densities. This paper presents some experimental results of turbulence properties inside such flows: the Reynolds tensions and the associated turbulent viscosity, and some characteristics linked with the statistical properties of the different turbulence scales. These last results allows to show the complexity of such flows characterized by the influence of external parameters (Reynolds number, initial density ratio, initial momentum flux) that govern the evolution of these parameters inside the jet from the nozzle up to regions where similarity properties are reached. (J.S.) 12 refs.

The JET diagnostic fast central acquisition and trigger system (abstract)

Science.gov (United States)

Edwards, A. W.; Blackler, K.

1995-01-01

Most plasma physics diagnostics sample at a fixed frequency that is normally matched to available memory limits. This technique is not appropriate for long pulse machines such as JET where sampling frequencies of hundreds of kHz are required to diagnose very fast events. As a result of work using real-time event selection within the previous JET soft x-ray diagnostic, a single data acquisition and event triggering system for all suitable fast diagnostics, the fast central acquisition and trigger system (Fast CATS), has been developed for JET. The front-end analog-to-digital conversion (ADC) part samples all channels at 250 kHz, with a 100 kHz pass band and a stop band of 125 kHz. The back-end data collection system is based around Texas Instruments TMS320C40 microprocessors. Within this system, two levels of trigger algorithms are able to evaluate data. The first level typically analyzes data on a per diagnostic and individual channel basis. The second level looks at the data from one or more diagnostics in a window around the time of interest flagged by the first level system. Selection criteria defined by the diagnosticians are then imposed on the results from the second level to decide whether that data should be kept. The use of such a system involving intelligent real time trigger algorithms and fast data analysis will improve both the quantity and quality of JET diagnostic data, while providing valuable input to the design of data acquisition systems for very long pulse machines such as ITER. This paper will give an overview of the various elements of this new system. In addition, first results from this system following the restart of JET operation will be presented.

Cryogenic filter method produces super-pure helium and helium isotopes

Science.gov (United States)

Hildebrandt, A. F.

1964-01-01

Helium is purified when cooled in a low pressure environment until it becomes superfluid. The liquid helium is then filtered through iron oxide particles. Heating, cooling and filtering processes continue until the purified liquid helium is heated to a gas.

High temperature reactor and helium turbine for naval propeller (Study of feasibility and performances of the system)

International Nuclear Information System (INIS)

Brisbois, J.; Malherbe, J.; Rastoin, J.; Courau; Metayer.

1976-01-01

The nuclear reactor HTGR can get an outlet helium temperature greater than 800 deg C. That gives the means to use an helium turbine in a direct cycle. This type of reactor has been studied for a supply-ship (25,000t, 85,000Cv) and feasibility of such a system can be proved without employing any unknown materials. Because the weakness of helium activity, only the core can be shielded. All the propeller system is inside a containment which has to stand with a small over pressure after a core depressurisation. An efficiency of 35% is realized in a compact set up. This nuclear propeller get a very long core life 860FPD with constant worth- and very flexible working conditions. The HTGR direct cycle make a naval propeller very attractive [fr

Retention of hydrogen isotopes and helium in nickel

Energy Technology Data Exchange (ETDEWEB)

Okada, Mitsumasa; Sato, Rikiya; Yamaguchi, Kenji; Yamawaki, Michio [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

1996-10-01

In the present study, a thin foil of nickel was irradiated by H{sub 2}{sup +}, D{sub 2}{sup +} and He{sup +} to a fluence of 1.2-6.0x10{sup 20}/m{sup 2} using the TBTS (Tritium Beam Test System) apparatus. The thermal desorption spectroscopy (TDS) technique was employed to evaluate the total amount of retained hydrogen isotope and helium atoms in nickel. In the spectra, two peaks appeared at 440-585K and 720-735K for helium. Hydrogen isotopes irradiation after helium preirradiation were found to enhance the helium release and to decrease the peak temperatures. Helium irradiation after hydrogen isotopes preirradiation were found to enhance the helium release, but the peak temperature showed little difference from that without preirradiation. (author)

Unexpected O and O3 production in the effluent of He/O2 microplasma jets emanating into ambient air

International Nuclear Information System (INIS)

Ellerweg, D; Von Keudell, A; Benedikt, J

2012-01-01

Microplasma jets are commonly used to treat samples in ambient air. The effect of admixing air into the effluent may severely affect the composition of the emerging species. Here, the effluent of a He/O 2 microplasma jet has been analyzed in a helium and in an air atmosphere by molecular beam mass spectrometry. First, the composition of the effluent in air was recorded as a function of the distance to determine how fast air admixes into the effluent. Then, the spatial distribution of atomic oxygen and ozone in the effluent was recorded in ambient air and compared with measurements in a helium atmosphere. Additionally, a fluid model of the gas flow with reaction kinetics of reactive oxygen species in the effluent was constructed. In ambient air, the O density declines only slightly faster with distance compared with a helium atmosphere. In contrast, the O 3 density in ambient air increases significantly faster with distance compared with a helium atmosphere. This unexpected behavior cannot be explained by simple recombination reactions of O atoms with O 2 molecules. A reaction scheme involving the reaction of plasma-produced excited O 2 * species of unknown identity with ground state O 2 molecules is proposed as a possible explanation for these observations. (paper)

Applicability of ASST-A helium refrigeration system for JLab End Station Refrigerator

Science.gov (United States)

Hasan, N.; Knudsen, P.; Ganni, V.

2017-12-01

The MØLLER experiment at Jefferson Lab (JLab) is a high power (5 kW) liquid hydrogen target scheduled to be operational in the 12 GeV-era. At present, cryogenic loads and targets at three of JLab’s four experimental halls are supported by the End Station Refrigerator (ESR) - a CTI/Helix 1.5 kW 4.5 K refrigerator. It is not capable of supporting the high power target load and a capacity upgrade of the ESR cryogenic system is essential. The ASST-A helium refrigeration system is a 4 kW 4.5 K refrigerator. It was designed and used for the Superconducting Super Collider Lab (SSCL) magnet string test and later obtained by JLab after the cancellation of that project. The modified ASST-A refrigeration system, which will be called ESR-II along with a support flow from JLab’s Central Helium Liquefier (CHL) is considered as an option for the End Station Refrigerator capacity upgrade. The applicability of this system for ESR-II under varying load conditions is investigated. The present paper outlines the findings of this process study.

Plasma bullet current measurements in a free-stream helium capillary jet

International Nuclear Information System (INIS)

Oh, Jun-Seok; Walsh, James L; Bradley, James W

2012-01-01

A commercial current monitor has been used to measure the current associated with plasma bullets created in both the positive and negative half cycles of the sinusoidal driving voltage sustaining a plasma jet. The maximum values of the positive bullet current are typically ∼750 µA and persist for 10 µs, while the peaks in the negative current of several hundred μA are broad, persisting for about 40 µs. From the time delay of the current peaks with increasing distance from the jet nozzle, an average bullet propagation speed has been measured; the positive and negative bullets travel at 17.5 km s −1 and 3.9 km s −1 respectively. The net space charge associated with the bullet(s) has also been calculated; the positive and negative bullets contain a similar net charge of the order of 10 −9 C measured at all monitor positions, with estimated charged particle densities n b of ∼10 10 –10 11 cm −3 in the bullet. (special)

Design, Fabrication, Installation and Commissioning of the Helium Refrigeration system Supporting Superconducting Radio Frequency Testing at Facility for Rare Isotope Beams at Michigan State University

Science.gov (United States)

Casagrande, F.; Fila, A.; Nguyen, C.; Tatsumoto, H.

2017-12-01

The Facility for Rare Isotope Beams (FRIB) will be a scientific user facility for the Office of Nuclear Physics in the U.S. Department of Energy Office of Science (DOE-SC). The FRIB linear accelerator (LINAC) will be comprised of cryomodules each with multiple Superconducting Radio Frequency (SRF) cavities operating at 2 K. A helium refrigeration system was designed, fabricated, installed and commissioned in the SRF high bay building to test and certify these cavities and cryomodules before installation in the FRIB LINAC tunnel. The helium refrigeration system includes a helium refrigerator which has nominal capacity of 900 W at 4 K, 5000 L liquid helium storage Dewar, helium gas storage, two room temperature vacuum pumps capable of 2.5 g/s each for 2 K testing, purifier, purifier recovery compressor, and the distribution system for liquid nitrogen and helium. The helium refrigeration system is now operational supporting three below grade cavity testing Dewars and one cryomodule testing bunker meeting the required throughput of 1 cavity per day.

Exploring the isopycnal mixing and helium-heat paradoxes in a suite of Earth system models

Science.gov (United States)

Gnanadesikan, A.; Pradal, M.-A.; Abernathey, R.

2015-07-01

This paper uses a suite of Earth system models which simulate the distribution of He isotopes and radiocarbon to examine two paradoxes in Earth science, each of which results from an inconsistency between theoretically motivated global energy balances and direct observations. The helium-heat paradox refers to the fact that helium emissions to the deep ocean are far lower than would be expected given the rate of geothermal heating, since both are thought to be the result of radioactive decay in Earth's interior. The isopycnal mixing paradox comes from the fact that many theoretical parameterizations of the isopycnal mixing coefficient ARedi that link it to baroclinic instability project it to be small (of order a few hundred m2 s-1) in the ocean interior away from boundary currents. However, direct observations using tracers and floats (largely in the upper ocean) suggest that values of this coefficient are an order of magnitude higher. Helium isotopes equilibrate rapidly with the atmosphere and thus exhibit large gradients along isopycnals while radiocarbon equilibrates slowly and thus exhibits smaller gradients along isopycnals. Thus it might be thought that resolving the isopycnal mixing paradox in favor of the higher observational estimates of ARedi might also solve the helium paradox, by increasing the transport of mantle helium to the surface more than it would radiocarbon. In this paper we show that this is not the case. In a suite of models with different spatially constant and spatially varying values of ARedi the distribution of radiocarbon and helium isotopes is sensitive to the value of ARedi. However, away from strong helium sources in the southeastern Pacific, the relationship between the two is not sensitive, indicating that large-scale advection is the limiting process for removing helium and radiocarbon from the deep ocean. The helium isotopes, in turn, suggest a higher value of ARedi below the thermocline than is seen in theoretical

Five second helium neutral beam injection using argon-frost cryopumping techniques

International Nuclear Information System (INIS)

Phillips, J.C.; Kellman, D.H.; Hong, R.; Kim, J.; Laughon, G.M.

1995-01-01

High power helium neutral beams for the heating of tokamak discharges can now be provided for 5 s by using argon cryopumping (of the helium gas) in the beamlines. The DIII-D neutral beam system has routinely provided up to 20 MW of deuterium neutral beam heating in support of experiments on the DIII-D tokamak. Operation of neutral beams with helium has historically presented a problem in that pulse lengths have been limited to 500 ms due to reliance solely on volume pumping of the helium gas. Helium is not condensed on the cryopanels. A system has now been installed to deposit a layer of argon frost on the DIII-D neutral beam cryopanels, between tokamak injection pulses. The layer serves to trap helium on the cryopanels providing sufficient pumping speed for 5 s helium beam extraction. The argon frosting hardware is now present on two of four DIII-D neutral beamlines, allowing injection of up to 6 MW of helium neutral beams per discharge, with pulse lengths of up to 5 s. The argon frosting system is described, along with experimental results demonstrating its effectiveness as a method of economically extending the capabilities of cryogenic pumping panels to allow multi-second helium neutral beam injection

Helium cryogenics

CERN Document Server

Van Sciver, Steven W

2012-01-01

Twenty five years have elapsed since the original publication of Helium Cryogenics. During this time, a considerable amount of research and development involving helium fluids has been carried out culminating in several large-scale projects. Furthermore, the field has matured through these efforts so that there is now a broad engineering base to assist the development of future projects. Helium Cryogenics, 2nd edition brings these advances in helium cryogenics together in an updated form. As in the original edition, the author's approach is to survey the field of cryogenics with emphasis on helium fluids. This approach is more specialized and fundamental than that contained in other cryogenics books, which treat the associated range of cryogenic fluids. As a result, the level of treatment is more advanced and assumes a certain knowledge of fundamental engineering and physics principles, including some quantum mechanics. The goal throughout the work is to bridge the gap between the physics and engineering aspe...

Liquid helium

CERN Document Server

Atkins, K R

1959-01-01

Originally published in 1959 as part of the Cambridge Monographs on Physics series, this book addresses liquid helium from the dual perspectives of statistical mechanics and hydrodynamics. Atkins looks at both Helium Three and Helium Four, as well as the properties of a combination of the two isotopes. This book will be of value to anyone with an interest in the history of science and the study of one of the universe's most fundamental elements.

Performance of cold compressors in a cooling system of an R and D superconducting coil cooled with subcooled helium

International Nuclear Information System (INIS)

Hamaguchi, S.; Imagawa, S.; Yanagi, N.; Takahata, K.; Maekawa, R.; Mito, T.

2006-01-01

The helical coils of large helical device (LHD) have been operated in saturated helium at 4.4 K and plasma experiments have been carried out at magnetic fields lower than 3 T for 8 years. Now, it is considered that the cooling system of helical coils will be improved to enhance magnetic fields in 2006. In the improvement, the helical coils will be cooled with subcooled helium and the operating temperature of helical coils will be lowered to achieve the designed field of 3 T and enhance cryogenic stabilities. Two cold compressors will be used in the cooling system of helical coils to generate subcooled helium. In the present study, the performance of cold compressors has been investigated, using a cooling system of R and D coil, to apply cold compressors to the cooling system of helical coils. Actual surge lines of cold compressors were observed and the stable operation area was obtained. Automatic operations were also performed within the area. In the automatic operations, the suitable pressure of a saturated helium bath, calculated from the rotation speed of the 1st cold compressor, was regulated by bypass valve. From these results, stable operations will be expected in the cooling system of helical coils

Improvement of In-Flight Alumina Spheroidization Process Using a Small Power Argon DC-RF Hybrid Plasma Flow System by Helium Mixture

Science.gov (United States)

Takana, Hidemasa; Jang, Juyong; Igawa, Junji; Nakajima, Tomoki; Solonenko, Oleg P.; Nishiyama, Hideya

2011-03-01

For the further improvement of in-flight alumina spheroidization process with a low-power direct-current radiofrequency (DC-RF) hybrid plasma flow system, the effect of a small amount of helium gas mixture in argon main gas and also the effect of increasing DC nozzle diameter on powder spheroidization ratio have been experimentally clarified with correlating helium gas mixture percentage, plasma enthalpy, powder in-flight velocity, and temperature. The alumina spheroidization ratio increases by helium gas mixture as a result of enhancement of plasma enthalpy. The highest spheroidization ratio is obtained by 4% mixture of helium in central gas with enlarging nozzle diameter from 3 to 4 mm, even under the constant low input electric power given to a DC-RF hybrid plasma flow system.

CALCULATED REGENERATOR PERFORMANCE AT 4 K WITH HELIUM-4 AND HELIUM-3

International Nuclear Information System (INIS)

Radebaugh, Ray; Huang Yonghua; O'Gallagher, Agnes; Gary, John

2008-01-01

The helium-4 working fluid in regenerative cryocoolers operating with the cold end near 4 K deviates considerably from an ideal gas. As a result, losses in the regenerator, given by the time-averaged enthalpy flux, are increased and are strong functions of the operating pressure and temperature. Helium-3, with its lower boiling point, behaves somewhat closer to an ideal gas in this low temperature range and can reduce the losses in 4 K regenerators. An analytical model is used to find the fluid properties that strongly influence the regenerator losses as well as the gross refrigeration power. The thermodynamic and transport properties of helium-3 were incorporated into the latest NIST regenerator numerical model, known as REGEN3.3, which was used to model regenerator performance with either helium-4 or helium-3. With this model we show how the use of helium-3 in place of helium-4 can improve the performance of 4 K regenerative cryocoolers. The effects of operating pressure, warm-end temperature, and frequency on regenerators with helium-4 and helium-3 are investigated and compared. The results are used to find optimum operating conditions. The frequency range investigated varies from 1 Hz to 30 Hz, with particular emphasis on higher frequencies

Pressurized helium II-cooled magnet test facility

International Nuclear Information System (INIS)

Warren, R.P.; Lambertson, G.R.; Gilbert, W.S.; Meuser, R.B.; Caspi, S.; Schafer, R.V.

1980-06-01

A facility for testing superconducting magnets in a pressurized bath of helium II has been constructed and operated. The cryostat accepts magnets up to 0.32 m diameter and 1.32 m length with current to 3000 A. In initial tests, the volume of helium II surrounding the superconducting magnet was 90 liters. Minimum temperature reached was 1.7 K at which point the pumping system was throttled to maintain steady temperature. Helium II reservoir temperatures were easily controlled as long as the temperature upstream of the JT valve remained above T lambda; at lower temperatures control became difficult. Positive control of the temperature difference between the liquid and cold sink by means of an internal heat source appears necessary to avoid this problem. The epoxy-sealed vessel closures, with which we have had considerable experience with normal helium vacuum, also worked well in the helium II/vacuum environment

Apparatus to measure low level helium for neutron dosimetry

Energy Technology Data Exchange (ETDEWEB)

Ozaki, Shuji; Takao, Yoshiyuki; Muramasu, Masatomo; Hida, Tomoya; Sou, Hirofumi; Nakashima, Hideki [Kyushu Univ., Fukuoka (Japan); Kanda, Yukinori

1998-03-01

An apparatus to measure low level helium in a solid sample for neutron dosimetry in the practical use such as area monitoring in the long-term and reactor surveillance was reported. In our previous work, the helium atoms measurement system (HAMS) was developed. A sample was evaporated in the furnace and the released gas from the sample was analyzed with the mass spectrometer of the system to determine the amount of helium contained in it. The system has been improved to advance the lower helium measurement limit in a solid sample for its application to an area monitoring system. The mass of a solid is up to 100mg. Two important points should be considered to advance the lower limit. One was to produce a high quality vacuum in the system chamber for suppressing background gases during the sample measurement. The other important point was to detect very small output from the mass spectrometer. A pulse counting system was used to get high sensitivity in the mass 4 analyzing. (author)

Spent Nuclear Fuel (SNF) Project Cask and MCO Helium Purge System Design Review Completion Report - Project A.5 and A.6

International Nuclear Information System (INIS)

ARD, K.E.

2000-01-01

This report documents the results of the design verification performed on the Cask and Multiple Canister Over-pack (MCO) Helium Purge System. The helium purge system is part of the Spent Nuclear Fuel (SNF) Project Cask Loadout System (CLS) at 100K area. The design verification employed the ''Independent Review Method'' in accordance with Administrative Procedure (AP) EN-6-027-01

Simulation of helium release in the Battelle Model Containment facility using OpenFOAM

Energy Technology Data Exchange (ETDEWEB)

Wilkening, Heinz; Ammirabile, Luca, E-mail: luca.ammirabile@ec.europa.eu

2013-12-15

Highlights: • The HYJET Jx7 hydrogen release experiment at BMC facility is studied using OpenFOAM. • The SST model and 2nd order numerics for momentum and species concentration are used. • The behaviour is captured well but helium concentration is generally over-predicted. • OpenFOAM needs smaller time steps, higher resolution, more CPU time compared to CFX. • The study shows the potential of open source CFD codes in some nuclear application. - Abstract: The open source CFD code OpenFOAM has been validated against an experiment of jet release phenomena in the Battelle Model Containment facility (BMC), and benchmarked with the Ansys CFX5.7 results. In the selected test, HYJET Jx7, helium was released into the containment at a speed of 42 m/s over a time of 200 s. The SST turbulence model was applied to model helium release and dispersion with both codes. The overall behaviour is captured adequately. However, there are still some noticeable differences between the CFX and OpenFOAM solutions. The study confirms the potential of using open source codes like OpenFOAM in some nuclear applications. Nevertheless further investigations and improvements are needed.

Simulation of helium release in the Battelle Model Containment facility using OpenFOAM

International Nuclear Information System (INIS)

Wilkening, Heinz; Ammirabile, Luca

2013-01-01

Highlights: • The HYJET Jx7 hydrogen release experiment at BMC facility is studied using OpenFOAM. • The SST model and 2nd order numerics for momentum and species concentration are used. • The behaviour is captured well but helium concentration is generally over-predicted. • OpenFOAM needs smaller time steps, higher resolution, more CPU time compared to CFX. • The study shows the potential of open source CFD codes in some nuclear application. - Abstract: The open source CFD code OpenFOAM has been validated against an experiment of jet release phenomena in the Battelle Model Containment facility (BMC), and benchmarked with the Ansys CFX5.7 results. In the selected test, HYJET Jx7, helium was released into the containment at a speed of 42 m/s over a time of 200 s. The SST turbulence model was applied to model helium release and dispersion with both codes. The overall behaviour is captured adequately. However, there are still some noticeable differences between the CFX and OpenFOAM solutions. The study confirms the potential of using open source codes like OpenFOAM in some nuclear applications. Nevertheless further investigations and improvements are needed

Experimental investigations of flow distribution in coolant system of Helium-Cooled-Pebble-Bed Test Blanket Module

Energy Technology Data Exchange (ETDEWEB)

Ilić, M.; Schlindwein, G., E-mail: georg.schlindwein@kit.edu; Meyder, R.; Kuhn, T.; Albrecht, O.; Zinn, K.

2016-02-15

Highlights: • Experimental investigations of flow distribution in HCPB TBM are presented. • Flow rates in channels close to the first wall are lower than nominal ones. • Flow distribution in central chambers of manifold 2 is close to the nominal one. • Flow distribution in the whole manifold 3 agrees well with the nominal one. - Abstract: This paper deals with investigations of flow distribution in the coolant system of the Helium-Cooled-Pebble-Bed Test Blanket Module (HCPB TBM) for ITER. The investigations have been performed by manufacturing and testing of an experimental facility named GRICAMAN. The facility involves the upper poloidal half of HCPB TBM bounded at outlets of the first wall channels, at outlet of by-pass pipe and at outlets of cooling channels in breeding units. In this way, the focus is placed on the flow distribution in two mid manifolds of the 4-manifold system: (i) manifold 2 to which outlets of the first wall channels and inlet of by-pass pipe are attached and (ii) manifold 3 which supplies channels in breeding units with helium coolant. These two manifolds are connected with cooling channels in vertical/horizontal grids and caps. The experimental facility has been built keeping the internal structure of manifold 2 and manifold 3 exactly as designed in HCPB TBM. The cooling channels in stiffening grids, caps and breeding units are substituted by so-called equivalent channels which provide the same hydraulic resistance and inlet/outlet conditions, but have significantly simpler geometry than the real channels. Using the conditions of flow similarity, the air pressurized at 0.3 MPa and at ambient temperature has been used as working fluid instead of HCPB TBM helium coolant at 8 MPa and an average temperature of 370 °C. The flow distribution has been determined by flow rate measurements at each of 28 equivalent channels, while the pressure distribution has been obtained measuring differential pressure at more than 250 positions. The

Reduction of hydrocarbon impurities in 200 l/h helium liquefier-refrigerator system

Science.gov (United States)

Yamada, Shuichi; Mito, Toshiyuki; Nishimura, Arata; Takahata, Kazuya; Satoh, Sadao; Yamamoto, Junya; Yamamura, Hidemasa; Masuda, Kaoru; Kashihara, Shinichirou; Fukusada, Katsuaki

1993-11-01

A cryogenic system with the capacity of 200 l/h or 500 W at 4.4 K was developed in order to supply the superconducting conductors and coils of the LHD. As a by-product of operating the cryogenic system, the impurity densities of hydrocarbon gases in the circulating helium gas became much larger than the expected values for this cryogenic system. So much larger in fact, that it became necessary to carefully monitor the operational conditions of the circulating compressor by means of gas chromatography. Impurity gas densities of oxygen, nitrogen, and ethane increased significantly when the output capacity of the compressor was reduced. In a two-stage oil injected compression system, with a variable stroke mechanism for a first stage, a reduction in the capacity of the first stage leads to a larger compression ratio for the second stage, and the temperature of the injected oil becomes higher. The production of the impurities in the helium might be caused by decomposition of the injected oil in the compressor. The compressor, therefore, was reconstructed such that the injection oil is supplied sufficiently, and the compression ratio division becomes even for each stage. It was confirmed that the impurities were not produced after the modification.

Computer-to-process interface in JET's control and diagnostic systems

International Nuclear Information System (INIS)

Fullard, K.; Dorling, S.; Van Montfoort, J.

1987-01-01

The JET Control and Data Acquisition System, CODAS, uses some 40,000 electrical signals to control and monitor JET's various systems. This paper describes the electronic equipment and the data transmission techniques which are used to route these signals to and from the centrally-located computers. Special emphasis has been placed on the practical aspects of building and maintaining such a large system of approaching 8,000 modules. Quantities and costs of the various classes of modules and cables are given together with an outline of the quality assurance and organisational techniques adopted

New helium spectrum variable and a new helium-rich star

International Nuclear Information System (INIS)

Walborn, N.R.

1974-01-01

HD 184927, known previously as a helium-rich star, has been found to have a variable helium spectrum; the equivalent widths of five He I lines are larger by an average of 46 percent on a 1974 spectrogram than on one obtained with the same equipment in 1970. HD 186205 has been found to be a new, pronounced helium-rich star. (auth)

Jet plume injection and combustion system for internal combustion engines

Science.gov (United States)

Oppenheim, Antoni K.; Maxson, James A.; Hensinger, David M.

1993-01-01

An improved combustion system for an internal combustion engine is disclosed wherein a rich air/fuel mixture is furnished at high pressure to one or more jet plume generator cavities adjacent to a cylinder and then injected through one or more orifices from the cavities into the head space of the cylinder to form one or more turbulent jet plumes in the head space of the cylinder prior to ignition of the rich air/fuel mixture in the cavity of the jet plume generator. The portion of the rich air/fuel mixture remaining in the cavity of the generator is then ignited to provide a secondary jet, comprising incomplete combustion products which are injected into the cylinder to initiate combustion in the already formed turbulent jet plume. Formation of the turbulent jet plume in the head space of the cylinder prior to ignition has been found to yield a higher maximum combustion pressure in the cylinder, as well as shortening the time period to attain such a maximum pressure.

The gas introduction system of JET

International Nuclear Information System (INIS)

Boschi, A.; Dietz, K.J.; Rebut, P.H.

1984-01-01

The Gas Introduction System of JET is designed to handle, measure, transfer and inject into the machine, at given rates and times, the quantities of gases required to feel the plasma discharges. The System is composed by a Gas Handling Unit for the gas preparation, and four identical Gas Introduction Modules which are positioned symmetrically at the machine. The lay-out and design of the different components is described and operational experience is presented. (author)

Reduction and degradation of amyloid aggregates by a pulsed radio-frequency cold atmospheric plasma jet

Energy Technology Data Exchange (ETDEWEB)

Bayliss, D L; Walsh, J L; Iza, F; Kong, M G [Department of Electronic and Electrical Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom); Shama, G [Department of Chemical Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)], E-mail: m.g.kong@lboro.ac.uk

2009-11-15

Surface-borne amyloid aggregates with mature fibrils are used as a non-infectious prion model to evaluate cold atmospheric plasmas (CAPs) as a prion inactivation strategy. Using a helium-oxygen CAP jet with pulsed radio-frequency (RF) excitation, amyloid aggregates deposited on freshly cleaved mica discs are reduced substantially leaving only a few spherical fragments of sub-micrometer sizes in areas directly treated by the CAP jet. Outside the light-emitting part of the CAP jet, plasma treatment results in a 'skeleton' of much reduced amyloid stacks with clear evidence of fibril fragmentation. Analysis of possible plasma species and the physical configuration of the jet-sample interaction suggests that the skeleton structures observed are unlikely to have arisen as a result of physical forces of detachment, but instead by progressive diffusion of oxidizing plasma species into porous amyloid aggregates. Composition of chemical bonds of this reduced amyloid sample is very different from that of intact amyloid aggregates. These suggest the possibility of on-site degradation by CAP treatment with little possibility of spreading contamination elsewhere , thus offering a new reaction chemistry route to protein infectivity control with desirable implications for the practical implementation of CAP-based sterilization systems.

Cryogenic system with GM cryocooler for krypton, xenon separation from hydrogen-helium purge gas

Energy Technology Data Exchange (ETDEWEB)

Chu, X. X.; Zhang, D. X.; Qian, Y.; Liu, W. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800 (China); Zhang, M. M.; Xu, D. [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China)

2014-01-29

In the thorium molten salt reactor (TMSR), fission products such as krypton, xenon and tritium will be produced continuously in the process of nuclear fission reaction. A cryogenic system with a two stage GM cryocooler was designed to separate Kr, Xe, and H{sub 2} from helium purge gas. The temperatures of two stage heat exchanger condensation tanks were maintained at about 38 K and 4.5 K, respectively. The main fluid parameters of heat transfer were confirmed, and the structural heat exchanger equipment and cold box were designed. Designed concentrations after cryogenic separation of Kr, Xe and H{sub 2} in helium recycle gas are less than 1 ppb.

Systems for the safe operation of the JET tokamak with tritium

International Nuclear Information System (INIS)

Stork, D.; Ageladarakis, P.; Bell, A.C.

1999-01-01

In 1997, the JET device was operated for an extensive campaign with deuterium-tritium (D-T) plasmas (the DTE1 campaign). A comprehensive network of machine protection systems was necessary so that this experimental campaign could be executed safely without damage to the machine or release of activated material. This network had been developed over many years of JET deuterium plasma operation and therefore the modifications for D-T operation was not a significant problem. The DTE1 campaign was executed successfully and safely and the machine protection systems proved reliable and robust and, in the limited cases where they were required to act, functioned correctly. The machine protection systems at JET are described and their categorisation and development over time are summarised. The management, commissioning and operational experience during DTE1 are discussed and some examples of fault scenarios are described. The experience with protection systems at JET highlights the importance of correct design and philosophy decisions being taken at an early stage. It is shown that this experience will be invaluable data input to the safe operation of future large fusion machines. (orig.)

Helium the disappearing element

CERN Document Server

Sears, Wheeler M

2015-01-01

The subject of the book is helium, the element, and its use in myriad applications including MRI machines, particle accelerators, space telescopes, and of course balloons and blimps. It was at the birth of our Universe, or the Big Bang, where the majority of cosmic helium was created; and stellar helium production continues. Although helium is the second most abundant element in the Universe, it is actually quite rare here on Earth and only exists because of radioactive elements deep within the Earth. This book includes a detailed history of the discovery of helium, of the commercial industry built around it, how the helium we actually encounter is produced within the Earth, and the state of the helium industry today. The gas that most people associate with birthday party balloons is running out. “Who cares?” you might ask. Well, without helium, MRI machines could not function, rockets could not go into space, particle accelerators such as those used by CERN could not operate, fiber optic cables would not...

Performance Testing of Jefferson Lab 12 GeV Helium Screw Compressors

Science.gov (United States)

Knudsen, P.; Ganni, V.; Dixon, K.; Norton, R.; Creel, J.

2015-08-01

Oil injected screw compressors have essentially superseded all other types of compressors in modern helium refrigeration systems due to their large displacement capacity, reliability, minimal vibration, and capability of handling helium's high heat of compression. At the present state of compressor system designs for helium refrigeration systems, typically two-thirds of the lost input power is due to the compression system. It is important to understand the isothermal and volumetric efficiencies of these machines to help properly design the compression system to match the refrigeration process. It is also important to identify those primary compressor skid exergetic loss mechanisms which may be reduced, thereby offering the possibility of significantly reducing the input power to helium refrigeration processes which are extremely energy intensive. This paper summarizes the results collected during the commissioning of the new compressor system for Jefferson Lab's (JLab's) 12 GeV upgrade. The compressor skid packages were designed by JLab and built to print by industry. They incorporate a number of modifications not typical of helium screw compressor packages and most importantly allow a very wide range of operation so that JLab's patented Floating Pressure Process can be fully utilized. This paper also summarizes key features of the skid design that allow this process and facilitate the maintenance and reliability of these helium compressor systems.

Jet Riemann-Lagrange Geometry Applied to Evolution DEs Systems from Economy

OpenAIRE

Neagu, Mircea

2007-01-01

The aim of this paper is to construct a natural Riemann-Lagrange differential geometry on 1-jet spaces, in the sense of nonlinear connections, generalized Cartan connections, d-torsions, d-curvatures, jet electromagnetic fields and jet Yang-Mills energies, starting from some given non-linear evolution DEs systems modelling economic phenomena, like the Kaldor model of the bussines cycle or the Tobin-Benhabib-Miyao model regarding the role of money on economic growth.

Five second helium neutral beam injection using argon-frost cryopumping techniques

International Nuclear Information System (INIS)

Phillips, J.C.; Kellman, D.H.; Hong, R.; Kim, J.; Laughon, G.M.

1995-10-01

High power helium neutral beams for the heating of tokamak discharges can now be provided for 5 s by using argon cryopumping (of the helium gas) in the beamlines. A system has now been installed to deposit a layer of argon frost on the DIII-D neutral beam cryopanels, between tokamak injection pulses. The layer serves to trap helium on the cryopanels providing sufficient pumping speed for 5 s helium beam extraction. The argon frosting hardware is now present on two of four DIII-D neutral beamlines, allowing injection of up to 6 MW of helium neutral beams per discharge, with pulse lengths of up to 5 s. The argon frosting system is described, along with experimental results demonstrating its effectiveness as a method of economically extending the capabilities of cryogenic pumping panels to allow multi-second helium neutral beam injection

Helium atmospheric pressure plasma jets touching dielectric and metal surfaces

Science.gov (United States)

Norberg, Seth A.; Johnsen, Eric; Kushner, Mark J.

2015-07-01

Atmospheric pressure plasma jets (APPJs) are being investigated in the context plasma medicine and biotechnology applications, and surface functionalization. The composition of the surface being treated ranges from plastics, liquids, and biological tissue, to metals. The dielectric constant of these materials ranges from as low as 1.5 for plastics to near 80 for liquids, and essentially infinite for metals. The electrical properties of the surface are not independent variables as the permittivity of the material being treated has an effect on the dynamics of the incident APPJ. In this paper, results are discussed from a computational investigation of the interaction of an APPJ incident onto materials of varying permittivity, and their impact on the discharge dynamics of the plasma jet. The computer model used in this investigation solves Poisson's equation, transport equations for charged and neutral species, the electron energy equation, and the Navier-Stokes equations for the neutral gas flow. The APPJ is sustained in He/O2 = 99.8/0.2 flowing into humid air, and is directed onto dielectric surfaces in contact with ground with dielectric constants ranging from 2 to 80, and a grounded metal surface. Low values of relative permittivity encourage propagation of the electric field into the treated material and formation and propagation of a surface ionization wave. High values of relative permittivity promote the restrike of the ionization wave and the formation of a conduction channel between the plasma discharge and the treated surface. The distribution of space charge surrounding the APPJ is discussed.

A new prototype of an electronic jet-ventilator and its humidification system

Science.gov (United States)

Kraincuk, Paul; Kepka, Anton; Ihra, Gerald; Schabernig, Christa; Aloy, Alexander

1999-01-01

Background: Adequate humidification in long-term jet ventilation is a critical aspect in terms of clinical safety. Aim: To assess a prototype of an electronic jet-ventilator and its humidification system. Methods: Forty patients with respiratory insufficiency were randomly allocated to one of four groups. The criterion for inclusion in this study was respiratory insufficiency exhibiting a Murray score above 2. The four groups of patients were ventilated with three different respirators and four different humidification systems. Patients in groups A and B received superimposed high-frequency jet ventilation (SHFJV) by an electronic jet-ventilator either with (group A) or without (group B) an additional humidification system. Patients in group C received high-frequency percussive ventilation (HFPV) by a pneumatic high-frequency respirator, using a hot water humidifier for warming and moistening the inspiration gas. Patients in group D received conventional mechanical ventilation using a standard intensive care unit respirator with a standard humidification system. SHFJV and HFPV were used for a period of 100 h (4days). Results: A significantly low inspiration gas temperature was noted in patients in group B, initially (27.2 ± 2.5°C) and after 2 days (28.0 ± 1.6°C) (P humidification associated with jet ventilation can be fully prevented by using this new jet-ventilator. These data were sustained by nondeteriorating MIS values at the end of the 4-day study period in groups A, C and D. PMID:11056732

The Local Helium Compound Transfer Lines for the Large Hadron Collider Cryogenic System

CERN Document Server

Parente, C; Munday, A; Wiggins, P

2006-01-01

The cryogenic system for the Large Hadron Collider (LHC) under construction at CERN will include twelve new local helium transfer lines distributed among five LHC points in underground caverns. These lines, being manufactured and installed by industry, will connect the cold boxes of the 4.5-K refrigerators and the 1.8-K refrigeration units to the cryogenic interconnection boxes. The lines have a maximum of 30-m length and may possess either small or large re-distribution units to allow connection to the interface ports. Due to space restrictions the lines may have complex routings and require several elbowed sections. The lines consist of a vacuum jacket, a thermal shield and either three or four helium process pipes. Specific internal and external supporting and compensation systems were designed for each line to allow for thermal contraction of the process pipes (or vacuum jacket, in case of a break in the insulation vacuum) and to minimise the forces applied to the interface equipment. Whenever possible, f...

Sonic Helium Detectors in the Fermilab Tevatron

Science.gov (United States)

Bossert, R. J.

2006-04-01

In the Fermilab Tevatron cryogenic system there are many remotely located low-pressure plate relief valves that must vent large volumes of cold helium gas when magnet quenches occur. These valves can occasionally stick open or not reseat completely, resulting in a large helium loss. As such, the need exists for a detector to monitor the relief valve's discharge area for the presence of helium. Due to the quantity needed, cost is an important factor. A unit has been developed and built for this purpose that is quite inexpensive. Its operating principle is based on the speed of sound, where two closely matched tubes operate at their acoustic resonant frequency. When helium is introduced into one of these tubes, the resulting difference in acoustic time of flight is used to trigger an alarm. At present, there are 39 of these units installed and operating in the Tevatron. They have detected many minor and major helium leaks, and have also been found useful in detecting a rise in the helium background in the enclosed refrigerator buildings. This paper covers the construction, usage and operational experience gained with these units over the last several years.

Sonic helium detectors in the Fermilab Tevatron

International Nuclear Information System (INIS)

Bossert, R.J.; Fermilab

2006-01-01

In the Fermilab Tevatron cryogenic system there are many remotely located low-pressure plate relief valves that must vent large volumes of cold helium gas when magnet quenches occur. These valves can occasionally stick open or not reseat completely, resulting in a large helium loss. As such, the need exists for a detector to monitor the relief valve's discharge area for the presence of helium. Due to the quantity needed, cost is an important factor. A unit has been developed and built for this purpose that is quite inexpensive. Its operating principle is based on the speed of sound, where two closely matched tubes operate at their acoustic resonant frequency. When helium is introduced into one of these tubes, the resulting difference in acoustic time of flight is used to trigger an alarm. At present, there are 39 of these units installed and operating in the Tevatron. They have detected many minor and major helium leaks, and have also been found useful in detecting a rise in the helium background in the enclosed refrigerator buildings. This paper covers the construction, usage and operational experience gained with these units over the last several years

The gas introduction system of JET

International Nuclear Information System (INIS)

Boschi, A.; Dietz, K.J.; Rebut, P.H.

1985-01-01

The Gas Introduction System of JET is designed to handle, measure, transfer and inject into the machine, at given rates and times, the quantitites of gases required to feed the plasma discharges. The System is composed by a Gas Handling Unit for the gas preparation, and four identical Gas Introduction Modules which are positioned symmetrically at the machine. In this paper the lay-out and design of the different components is described and operational experience is presented

Helium crystals

International Nuclear Information System (INIS)

Lipson, S.G.

1987-01-01

Hexagonal close-packed helium crystals in equilibrium with superfluid have been found to be one of the few systems in which an anisotropic solid comes into true thermodynamic equilibrium with its melt. The discovery of roughening transitions at the liquid-solid interface have shown this system to be ideal for the study of the statistical mechanics of interface structures. We describe the effect of roughening on the shape and growth of macroscopic crystals from both the theoretical and experimental points of view. (author)

Active control of continuous air jet with bifurcated synthetic jets

Directory of Open Access Journals (Sweden)

Dančová Petra

2017-01-01

Full Text Available The synthetic jets (SJs have many significant applications and the number of applications is increasing all the time. In this research the main focus is on the primary flow control which can be used effectively for the heat transfer increasing. This paper deals with the experimental research of the effect of two SJs worked in the bifurcated mode used for control of an axisymmetric air jet. First, the control synthetic jets were measured alone. After an adjustment, the primary axisymmetric jet was added in to the system. For comparison, the primary flow without synthetic jets control was also measured. All experiments were performed using PIV method whereby the synchronization between synthetic jets and PIV system was necessary to do.

Computer-to-process interface in JET's control and diagnostic systems

International Nuclear Information System (INIS)

Fullard, K.; Dorling, S.E.; Montfoort, J.E. van

1986-01-01

The JET Control and Data Acquisition System, CODAS, uses some 40,000 electrical signals to control and monitor JET's various systems. This paper describes the electronic equipment and the data transmission techniques which are used to route these signals to and from the centrally-located computers is described. Special emphasis has been placed on the practical aspects of building and maintaining such a large system of approaching 8,000 modules. Quantities and costs of the various classes of modules and cables are given together with an outline of the quality assurance and organisational techniques adopted. (author)

Development of a gas-jet-coupled multitarget system for multitracer production

International Nuclear Information System (INIS)

Haba, H.; Kaji, D.; Kanayama, Y.; Igarashi, K.; Enomoto, S.

2005-01-01

de021741792A new multitracer production system, which consists of a gas-jet-coupled multitarget system for short-lived radioactive tracers and a gas- and water-cooled target system for intense beam irradiations, has been installed on a beam line of the K540-MeV RIKEN Ring Cyclotron. The performance of the gas-jet system was investigated with 50 radionuclides of 18 elements produced in the 135 MeV nucl. -1 - 14 N induced reaction on nat Cu. The gas-jet efficiencies of the nuclides varying from 61 Cu to 24 Na, except for the chlorine isotopes, show a smooth variation as a function of the mass difference between a product and a target. The multitracers on the nat Ag and 197 Au targets were also produced by the 135 MeV nucl. -1 - 14 N beam with the intensity of 0.7 pμA, which was more than seven times the limit of the previous system. (orig.)

The assessment of helium purification system of small power HTGR

International Nuclear Information System (INIS)

Siti Alimah; Sriyono

2016-01-01

The helium purification system (HPS) is one of safety system of High Temperature Gas-cooled Reactor. HPS removes impurities in the primary coolant, so that the impact on structure, system and component (SSC) is minimized. The two impurity types are particulates (carbon dust, fission products (Kr, Xe, Cs etc.) and the gases (O_2, N_2, H_2O, CH_4, CO, CO_2 and H_2). Every reactor has a different impurity limit during normal operation, depends on the reactor power, energy conversion system and fuel type. This paper discusses the HPS on HTR-10, HTTR and Indonesian RDE conceptual design. The purpose of this assessment is to determine the optimum HPS design as a role model for Indonesian RDE. The utilized methodology is a literature study based on the operating experiences of both HTR-10 and HTTR as well as the evaluation of RDE conceptual design. This study focuses on the impurities limit during normal operation, the main components of HPS, mass flow-rate and regeneration process. The main component that used in HPS for HTR-10, HTTR and RDE are similar i.e. filter, CuO column, water cooler, molecular sieve bed and cryogenic activated carbon bed. Refer to the HTR-10 and HTTR operational experiences, both of those reactors have a purification systems that capable to maintain the helium purity, even though the impurities limit are different. The HPS of HTTR Japan has a stricter impurities limit that N_2, CH_4, and O_2 should not be contained at all during normal operation and the pre-charcoal trap is used to adsorb the fine dust below 0.1 micron. Both of these parameters can be adopted to the RDE's HPS design to minimize the effect of impurities to SSC. (author)

A liquid helium saver

International Nuclear Information System (INIS)

Avenel, O.; Der Nigohossian, G.; Roubeau, P.

1976-01-01

A cryostat equipped with a 'liquid helium saver' is described. A mass flow rate M of helium gas at high pressure is injected in a counter-flow heat exchanger extending from room to liquid helium temperature. After isenthalpic expansion through a calibrated flow impedance this helium gas returns via the low pressure side of the heat exchanger. The helium boil-off of the cryostat represents a mass flow rate m, which provides additional precooling of the incoming helium gas. Two operating regimes appear possible giving nearly the same efficiency: (1) high pressure (20 to 25 atm) and minimum flow (M . L/W approximately = 1.5) which would be used in an open circuit with helium taken from a high pressure cylinder; and (2) low pressure (approximately = 3 atm), high flow (M . L/W > 10) which would be used in a closed circuit with a rubber diaphragm pumping-compressing unit; both provide a minimum theoretical boil-off factor of about 8%. Experimental results are reported. (U.K.)

Design and analysis of Helium Brayton cycle for energy conversion system of RGTT200K

International Nuclear Information System (INIS)

Ignatius Djoko Irianto

2016-01-01

The helium Brayton cycle for the design of cogeneration energy conversion system for RGTT200K have been analyzed to obtain the higher thermal efficiency and energy utilization factor. The aim of this research is to analyze the potential of the helium Brayton cycle to be implemented in the design of cogeneration energy conversion system of RGTT200K. Three configuration models of cogeneration energy conversion systems have been investigated. In the first configuration model, an intermediate heat exchanger (IHX) is installed in series with the gas turbine, while in the second configuration model, IHX and gas turbines are installed in parallel. The third configuration model is similar to the first configuration, but with two compressors. Performance analysis of Brayton cycle used for cogeneration energy conversion system of RGTT200K has been done by simulating and calculating using CHEMCAD code. The simulation result shows that the three configuration models of cogeneration energy conversion system give the temperature of thermal energy in the secondary side of IHX more than 800 °C at the reactor coolant mass flow rate of 145 kg/s. Nevertheless, the performance parameters, which include thermal efficiency and energy utilization factor (EUF), are different for each configuration model. By comparing the performance parameter in the three configurations of helium Brayton cycle for cogeneration energy conversion systems RGTT200K, it is found that the energy conversion system with a first configuration has the highest thermal efficiency and energy utilization factor (EUF). Thermal efficiency and energy utilization factor for the first configuration of the reactor coolant mass flow rate of 145 kg/s are 35.82 % and 80.63 %. (author)

The Role of the JET Project in Global Fusion Research

DEFF Research Database (Denmark)

Jensen, Vagn Orla

1983-01-01

The aim of nuclear fusion research is to make fusion energy available as a new energy source. Fusion processes occur naturally in the sun, where hydrogen nuclei release energy by combining to form helium. A fusion reactor on earth will require even higher temperatures than in the interior...... of the sun, and it will be based on deuterium and tritium reactions. JET (Joint European Torus) is a major fusion experiment now under construction near Abingdon in the UK It is aimed at producing conditions approximating those necessary in a fusion reactor. The results expected from JET should permit...... a realistic evaluation of the prospects for fusion power and serve as a basis for the design of the next major fusion experiment....

The new Ex-Vessel Magnetic Diagnostics System for JET

International Nuclear Information System (INIS)

Coccorese, V.; Artaserse, G.; Quercia, A.; Chitarin, G.; Peruzzo, S.; Edlington, T.; Gerasimov, S.; Sowden, C.

2006-01-01

A new system of magnetic probes was installed during the 2005 shutdown and was commissioned during the 2005/06 restart phase of JET. The system has been developed in the framework of the JET enhancement project on Magnetic Diagnostics, which aims to improve the equilibrium reconstruction and the real time control in JET, by means of 98 new field measurements as well as of new software tools. The subsystem presented in the paper includes probes located outside the vessel and it is made of 8 pickup coils, 8 Hall probes and 6 flux loops. The objective of this subsystem is twofold: i) provide experimental data for a better modelling of the iron in the axisymmetric codes for plasma equilibrium reconstruction; ii) test the reliability of direct field measurements. The new sensors are located very near to the iron structure, so to provide useful information for the online tuning of the code parameters representing the iron characteristics. Direct field measurements from Hall probes are used to correct the drift of the integrators of the pickup coils signals. This feature will be crucial for future ITER-like devices, where long lasting flat top phases are expected, in a high neutron yield and a high temperature environment. After a general overview of the system, the paper describes the major manufacturing and installation issues, including the construction of the supports and probes as well as the acceptance tests before and after installation. The functional commissioning of the system, which was successfully concluded during the restart phase, is also illustrated. It includes the integration of the new signals in the JET CODAS system and the analysis of several discharges with and without plasma. The critical aspects of the assessment of the reliability of the signals are shown and commented on. (author)

Conceptual design of helium experimental loop

International Nuclear Information System (INIS)

Yu Xingfu; Feng Kaiming

2007-01-01

In a future demonstration fusion power station (DEMO), helium is envisaged as coolant for plasma facing components, such as blanket and dive,or. All these components have a very complex geometry, with many parallel cooling channels, involving a complex helium flow distribution. Test blanket modules (TBM) of this concept will under go various tests in the experimental reactor ITER. For the qualification of TBM, it is indispensable to test mock-ups in a helium loop under realistic pressure and temperature profiles, in order to validate design codes, especially regarding mass flow and heat transition processes in narrow cooling channels. Similar testing must be performed for DEMO blanket, currently under development. A Helium Experimental Loop (HELOOP) is planed to be built for TBM tests. The design parameter of temperature, pressure, flow rate is 550 degree C, 10 MPa, l kg/s respectively. In particular, HELOOP is able to: perform full-scale tests of TBM under realistic conditions; test other components of the He-cooling system in ITER; qualify the purification circuit; obtain information for the design of the ITER cooling system. The main requirements and characteristics of the HELOOP facility and a preliminary conceptual design are described in the paper. (authors)

Disruption mitigation with high-pressure helium gas injection on EAST tokamak

Science.gov (United States)

Chen, D. L.; Shen, B.; Granetz, R. S.; Qian, J. P.; Zhuang, H. D.; Zeng, L.; Duan, Y.; Shi, T.; Wang, H.; Sun, Y.; Xiao, B. J.

2018-03-01

High pressure noble gas injection is a promising technique to mitigate the effect of disruptions in tokamaks. In this paper, results of mitigation experiments with low-Z massive gas injection (helium) on the EAST tokamak are reported. A fast valve has been developed and successfully implemented on EAST, with valve response time  ⩽150 μs, capable of injecting up to 7 × 1022 particles, corresponding to 300 times the plasma inventory. Different amounts of helium gas were injected into stable plasmas in the preliminary experiments. It is seen that a small amount of helium gas (N_He≃ N_plasma ) can not terminate a discharge, but can trigger MHD activity. Injection of 40 times the plasma inventory impurity (N_He≃ 40× N_plasma ) can effectively radiate away part of the thermal energy and make the electron density increase rapidly. The mitigation result is that the current quench time and vertical displacement can both be reduced significantly, without resulting in significantly higher loop voltage. This also reduces the risk of runaway electron generation. As the amount of injected impurity gas increases, the gas penetration time decreases slowly and asymptotes to (˜7 ms). In addition, the impurity gas jet has also been injected into VDEs, which are more challenging to mitigate that stable plasmas.

New jet-aeration system using 'Supercavitation'.

Science.gov (United States)

Schmid, Andreas

2010-03-01

A newly developed fine bubble aeration system, by which air is transferred under supercavitation conditions, shows a clearly better performance than traditional, well-known aerators that rely on the jet-pump principle and its performance can be compared to oxygen transfer rates achieved in membrane and foil plate aerators. A prototype supercavitation aerator installed at a sewage treatment plant revealed an air input rate, which was about one third lower than that of the jet-pump system, which it replaced. In spite of this low air input rate, the daily demand of pure oxygen for the additionally installed membrane aeration system went down by approximately 49%, from the original level of about 1,200 m(3)/day to about 600 m(3)/day-and this over a test period of more than 7 months. The observed high oxygen transfer rates cannot be explained by traditional mass transfer mechanisms. It is assumed that a large amount of water being transferred into the gas phase by supercavitation contacting directly oxygen also in the gas phase and thereby overcoming mass transfer hindrances which might be favoured by hydroxyl radicals. With this new aerator, during the first 3 months of test phase, already more than 10,000 Euros had been saved because of the reduced pure oxygen demand.

Atmospheric pressure He-air plasma jet: Breakdown process and propagation phenomenon

International Nuclear Information System (INIS)

Begum, Asma; Laroussi, Mounir; Pervez, Mohammad Rasel

2013-01-01

In this paper He-discharge (plasma jet/bullet) in atmospheric pressure air and its progression phenomenon has been studied experimentally using ICCD camera, optical emission spectroscopy (OES) and calibrated dielectric probe measurements. The repetitive nanosecond pulse has applied to a plasma pencil to generate discharge in the helium gas channel. The discharge propagation speed was measured from the ICCD images. The axial electric field distribution in the plasma jet is inferred from the optical emission spectroscopic data and from the probe measurement. The correlation between the jet velocities, jet length with the pulse duration is established. It shows that the plasma jet is not isolated from the input voltage along its propagation path. The discharge propagation speed, the electron density and the local and average electric field distribution along the plasma jet axis predicted from the experimental results are in good agreement with the data predicted by numerical simulation of the streamer propagation presented in different literatures. The ionization phenomenon of the discharge predicts the key ionization parameters, such as speed, peak electric field in the front, and electron density. The maximum local electric field measured by OES is 95 kV/cm at 1.3 cm of the jet axis, and average EF measured by probe is 24 kV/cm at the same place of the jet. The average and local electron density estimated are in the order of 10 11 cm -3 and it reaches to the maximum of 10 12 cm -3 .

Battery-Powered RF Pre-Ionization System for the Caltech Magnetohydrodynamically-Driven Jet Experiment: RF Discharge Properties and MHD-Driven Jet Dynamics

Science.gov (United States)

Chaplin, Vernon H.

This thesis describes investigations of two classes of laboratory plasmas with rather different properties: partially ionized low pressure radiofrequency (RF) discharges, and fully ionized high density magnetohydrodynamically (MHD)-driven jets. An RF pre-ionization system was developed to enable neutral gas breakdown at lower pressures and create hotter, faster jets in the Caltech MHD-Driven Jet Experiment. The RF plasma source used a custom pulsed 3 kW 13.56 MHz RF power amplifier that was powered by AA batteries, allowing it to safely float at 4-6 kV with the cathode of the jet experiment. The argon RF discharge equilibrium and transport properties were analyzed, and novel jet dynamics were observed. Although the RF plasma source was conceived as a wave-heated helicon source, scaling measurements and numerical modeling showed that inductive coupling was the dominant energy input mechanism. A one-dimensional time-dependent fluid model was developed to quantitatively explain the expansion of the pre-ionized plasma into the jet experiment chamber. The plasma transitioned from an ionizing phase with depressed neutral emission to a recombining phase with enhanced emission during the course of the experiment, causing fast camera images to be a poor indicator of the density distribution. Under certain conditions, the total visible and infrared brightness and the downstream ion density both increased after the RF power was turned off. The time-dependent emission patterns were used for an indirect measurement of the neutral gas pressure. The low-mass jets formed with the aid of the pre-ionization system were extremely narrow and collimated near the electrodes, with peak density exceeding that of jets created without pre-ionization. The initial neutral gas distribution prior to plasma breakdown was found to be critical in determining the ultimate jet structure. The visible radius of the dense central jet column was several times narrower than the axial current channel

High Reynolds number flows using liquid and gaseous helium

International Nuclear Information System (INIS)

Donnelly, R.J.

1991-01-01

Consideration is given to liquid and gaseous helium as test fluids, high Reynolds number test requirements in low speed aerodynamics, the measurement of subsonic flow around an appended body of revolution at cryogenic conditions in the NTF, water tunnels, flow visualization, the six component magnetic suspension system for wind tunnel testing, and recent aerodynamic measurements with magnetic suspension systems. Attention is also given to application of a flow visualization technique to a superflow experiment, experimental investigations of He II flows at high Reynolds numbers, a study of homogeneous turbulence in superfluid helium, and thermal convection in liquid helium

Dynamic modeling and simulation of the superconducting super collider cryogenic helium system

International Nuclear Information System (INIS)

Hartzog, D.G.; Fox, V.G.; Mathias, P.M.; Nahmias, D.; McAshan, M.; Carcagno, R.

1989-01-01

To study the operation of the Superconducting Super Collider (SSC) cryogenic system during transient operating conditions, they have developed and programmed in FORTRAN, a time-dependent, nonlinear, homogeneous, lumped-parameter simulation model of the SSC cryogenic system. This dynamic simulator has a modular structure so that process flowsheet modifications can be easily accommodated with minimal recoding. It uses the LSODES integration package to advance the solution in time. For helium properties it uses Air Products implementation of the standard thermodynamic model developed by the NBS. Two additional simplified helium thermodynamic models developed by Air Products are available as options to reduce computation time. To facilitate the interpretation of output, they have linked the simulator to the speakeasy conversational language. The authors present a flowsheet of the process simulated, and the material and energy balances used in the engineering models. They then show simulation results for three transient operating scenarios: startup of the refrigeration system from standby to full load; the loss of 4K refrigeration caused by the tripping of one of two parallel compressors in a sector; and a full-field quench of a single magnet half-cell. They discuss the response of the fluid within the cryogenic circuits during these scenarios. 14 refs., 19 figs., 2 tabs

Canada's helium output rising fast

Energy Technology Data Exchange (ETDEWEB)

1966-12-01

About 12 months from now, International Helium Limited will be almost ready to start up Canada's second helium extraction plant at Mankota, in Saskatchewan's Wood Mountain area about 100 miles southwest of Moose Jaw. Another 80 miles north is Saskatchewan's (and Canada's) first helium plant, operated by Canadian Helium and sitting on a gas deposit at Wilhelm, 9 miles north of Swift Current. It contains almost 2% helium, some COD2U, and the rest nitrogen. One year in production was apparently enough to convince Canadian Helium that the export market (it sells most of its helium in W. Europe) can take a lot more than it's getting. Construction began this summer on an addition to the Swift Current plant that will raise its capacity from 12 to 36MMcf per yr when it goes on stream next spring. Six months later, International Helium's 40 MMcf per yr plant to be located about 4 miles from its 2 Wood Mountain wells will double Canada's helium output again.

Diffusion of helium and nucleation-growth of helium-bubbles in metallic materials

International Nuclear Information System (INIS)

Zhang Chonghong; Chen Keqin; Wang Yinshu

2001-01-01

Studies of diffusion and aggregation behaviour of helium in metallic materials are very important to solve the problem of helium embrittlement in structural materials used in the environment of nuclear power. Experimental studies on helium diffusion and aggregation in austenitic stainless steels in a wide temperature range have been performed in authors' research group and the main results obtained are briefly summarized. The mechanism of nucleation-growth of helium-bubbles has been discussed and some problems to be solved are also given

The scientific success of JET

International Nuclear Information System (INIS)

Keilhacker, M.; Gibson, A.; Gormezano, C.; Rebut, P.H.

2001-01-01

The paper highlights the JET work in physics and technology during the period of the JET Joint Undertaking (1978-1999), with special emphasis on what has been learned for extrapolation to a NEXT STEP device. - Global confinement scaling has been extended to high currents and heating powers. Dimensionless scaling experiments of ELMy H mode plasmas suggest that bulk plasma transport is gyro-Bohm and predict ignition for a device with ITER-FDR parameters. Experiments in which the plasma elongation and triangularity were varied independently show a strong increase of confinement time with elongation (τ E ∼κ α 0.8±0.3 ), thus supporting a basic design principle of ITER-FEAT. With the Pellet Enhanced Performance (PEP) mode, JET has discovered the beneficial effect of reversed magnetic shear on confinement, opening the possibility of advanced tokamak scenarios. - With a three stage programme of progressively more closed divertors, JET has demonstrated the benefits of divertor closure, in particular, of high divertor neutral pressure which facilitates helium removal. It has also shown that in detached (or semidetached) radiative divertor plasmas the average power load on the target plates of a NEXT STEP device should be tolerable but, in addition, that the transient power loads during ELMs could cause problems. - In 1991 JET has demonstrated the first ever controlled production of a megawatt of fusion power. More extensive D-T experiments in 1997 (DTE1) have established new records in fusion performance: 16 MW transient fusion power with Q in =0.62 (i.e. close to breakeven, Q in =1) and 4 MW steady state fusion power with Q in =0.18 for 4 s. DTE1 has also allowed a successful test of various reactor ICRF heating schemes and a clear demonstration of alpha particle heating, consistent with classical expectations. - JET has developed and tested some of the most important technologies for a NEXT STEP and a reactor, in particular the safe handling of tritium and the

Reduction of hydrocarbon impurities in 200 L/H helium liquefier-refrigerator system

International Nuclear Information System (INIS)

Yamada, Shuichi; Mito, Toshiyuki; Nishimura, Arata

1993-11-01

A cryogenic system with the capacity of 200 1/h or 500 W at 4.4 K has been operated to develop the superconducting conductors and coils for the LHD. The system has contributed in various superconducting technologies along with the dc 75kA power supply and 10 MN mechanical testing machine, and completed the basic R and D works of the LHD. On the way of operating the cryogenic system, impurity densities of hydrocarbon gases in circulating helium gas became much larger than the expected values for this cryogenic system, so that the densities of some impurity gases were carefully monitored in reference to the operational conditions of circulating compressor by using a gas chromatography. Impurity gas densities of oxygen, nitrogen and ethane increased obviously, when the output capacity of the compressor was reduced. In a two-stage oil injected compression system with a variable stroke mechanism for a first stage, a reduction in the capacity of the first stage leads to a larger compression ratio for the second stage, and the temperature of the injected oil becomes higher. The production of the impurities in the helium might be caused by cracking a part of injected oil in the compressor. The compressor, therefore, was reconstructed such that the injection oil is supplied sufficiently and the compression ratio division becomes even for each stage. It was confirmed that the impurities are not produced now after modification. (author)

Development of non-thermal plasma jet and its potential application for color degradation of organic pollutant in wastewater treatment

Science.gov (United States)

Pirdo Kasih, Tota; Kharisma, Angel; Perdana, Muhammad Kevin; Murphiyanto, Richard Dimas Julian

2017-12-01

This paper presents the development of non-thermal plasma-based AOPs for color degradation in wastewater treatment. The plasma itself was generated by an in-house high voltage power supply (HVPS). Instead of gas-phase plasma system, we applied plasma jet system underwater during wastewater treatment without additional any chemicals (chemical-free processing). The method is thought to maximize the energy transfer and increase the efficient interaction between plasma and solution during the process. Our plasma jet system could proceed either by using helium (He), argon (Ar) and air as the medium in an open air atmosphere. Exploring the developed plasma to be applied in organic wastewater treatment, we demonstrated that the plasma jet could be generated underwater and yields in color degradation of methylene blue (MB) wastewater model. When using Ar gas as a medium, the color degradation of MB could be achieved within 90 minutes. Whereas, by using Ar with an admixing of oxygen (O2) gas, the similar result could be accomplished within 60 minutes. Additional O2 gas in the latter might produce more hydroxyl radicals and oxygen-based species which speed up the oxidative reaction with organic pollutants, and hence accelerate the process of color degradation.

Commissioning of a 20 K Helium Refrigeration System for NASA-JSC Chamber A

Science.gov (United States)

Homan, J.; Redman, R.; Ganni, V.; Sidi-Yekhlef, A.; Knudsen, P.; Norton, R.; Lauterbach, J.; Linza, R.; Vargas, G.

2013-01-01

A new 20 K helium refrigerator installed at NASA Johnson Space Center s Space Environment Simulation Laboratory (SESL) was successfully commissioned and tested in 2012. The refrigerator is used to create a deep space environment within SESL s Chamber A to perform ground testing of the James Webb Space Telescope (JWST). The chamber previously and currently still has helium cryo-pumping panels (CPP) and liquid nitrogen shrouds used to create low earth orbit environments. Now with the new refrigerator and new helium shrouds the chamber can create a deep space environment. The process design, system analysis, specification development, and commissioning oversight were performed by the cryogenics department at Jefferson Lab, while the contracts and system installation was performed by the ESC group at JSC. Commissioning data indicate an inverse coefficient of performance better than 70 W/W for a 18 kW load at 20 K (accounting for liquid nitrogen pre-cooling power) that remains essentially constant down to one third of this load. Even at 10 percent of the maximum capacity, the performance is better than 150 W/W at 20 K. The refrigerator exceeded all design goals and demonstrated the ability to support a wide load range from 10 kW at 15 K to 100 kW at 100 K. The refrigerator is capable of operating at any load temperature from 15 K to ambient with tight temperature stability. The new shroud (36 tons of aluminum) can be cooled from room temperature to 20 K in 24 hours. This paper will outline the process design and commissioning results.

submitter Superconducting instrumentation for high Reynolds turbulence experiments with low temperature gaseous helium

CERN Document Server

Pietropinto, S; Baudet, C; Castaing, B; Chabaud, B; Gagne, Y; Hébral, B; Ladam, Y; Lebrun, P; Pirotte, O; Roche, P

2003-01-01

Turbulence is of common experience and of high interest for industrial applications, despite its physical grounds is still not understood. Cryogenic gaseous helium gives access to extremely high Reynolds numbers (Re). We describe an instrumentation hosted in CERN, which provides a 6 kW @ 4.5 K helium refrigerator directly connected to the experiment. The flow is a round jet; the flow rates range from 20 g/s up to 260 g/s at 4.8 K and about 1.2 bar, giving access to the highest controlled Re flow ever developed. The experimental challenge lies in the range of scales which have to be investigated: from the smallest viscous scale η, typically 1 μm at Re=107 to the largest L∼10 cm. The corresponding frequencies: f=v/η can be as large as 1 MHz. The development of an original micrometric superconducting anemometer using a hot spot and its characteristics will be discussed together with its operation and the perspectives associated with superconducting anemometry.

A prestressed concrete pressure vessel for helium high temperature reactor system

International Nuclear Information System (INIS)

Horner, R.M.W.; Hodzic, A.

1976-01-01

A novel prestressed concrete pressure vessel has been developed to provide the primary containment for a fully integrated system comprising a high temperature nuclear reactor, three horizontally mounted helium turbines, associated heat exchangers and inter-connecting ducts. The design and analysis of the pressure vessel is described. Factors affecting the final choice of layout are discussed, and earlier development work seeking to resolve the conflicting requirements of the structural, mechanical, and system engineers outlined. Proposals to increase the present output of about 1000 MW of electrical power to over 3000 MW, by incorporating four turbines in a single pressure vessel are presented. (author)

Gas mixing under the influence of thermal-dynamic parameters such as buoyancy, jet momentum and fan-induced convection

International Nuclear Information System (INIS)

Chan, C.K.; Jones, S.C.A.

1994-01-01

Various scaling parameters for simulating mixing under the influence of buoyancy, jet momentum, and fan-induced convection were examined. Their significance was assessed by comparing the mixing of helium (a simulant for hydrogen) with air in a large-scale enclosure (1.8 m x 1.8 m x 1.8 m) to the mixing of salt-water with fresh-water in a small-scale enclosure (1/6 the size). The advantage of using the salt-water/freshwater technique is that it allows the characteristic flow regime (either turbulent or laminar flow) in the full-scale containment to be maintained in the reduced scale containment. A smoke technique for flow visualization was used to examine the mixing of the helium with air. For the small-scale salt-water/fresh-water experiment, fluorescent dye was used to provide a means to visualize the mixing process. The mixing behaviour in both sets of experiments were analyzed based on video records and concentration measurements in ten locations. Measurements showed that depending on the recirculation and jet flow rates, the injected salt-water (in small-scale experiments) and helium (in large-scale experiments) can disperse sufficiently quickly to produce an essentially 'well mixed' condition rendering the concentration measurements insensitive to the variation in the Froude or the Grashof Numbers. (author)

Consolidated Laser-Induced Fluorescence Diagnostic Systems for the NASA Ames Arc Jet Facilities

Science.gov (United States)

Grinstead, Jay; Wilder, Michael C.; Porter, Barry; Brown, Jeff; Yeung, Dickson; Battazzo, Steve; Brubaker, Tim

2016-01-01

The spectroscopic diagnostic technique of two photon absorption laser-induced fluorescence (TALIF) of atomic species for non-intrusive arc jet flow property measurement was first implemented at NASA Ames in the mid-1990s. Use of TALIF expanded at NASA Ames and to NASA Johnsons arc jet facility in the late 2000s. In 2013-2014, NASA combined the agency's large-scale arc jet test capabilities at NASA Ames. Concurrent with that effort, the agency also sponsored a project to establish two comprehensive LIF diagnostic systems for the Aerodynamic Heating Facility (AHF) and Interaction Heating Facility (IHF) arc jets. The scope of the project enabled further engineering development of the existing IHF LIF system as well as the complete reconstruction of the original AHF LIF system. The updated LIF systems are identical in design and capability. They represent the culmination of over 20 years of development experience in transitioning a specialized laboratory research tool into a measurement system for large-scale, high-demand test facilities. This paper documents the overall system design from measurement requirements to implementation. Representative data from the redeveloped AHF and IHF LIF systems are also presented.

NASA Jet Noise Research

Science.gov (United States)

Henderson, Brenda

2016-01-01

The presentation highlights NASA's jet noise research for 2016. Jet-noise modeling efforts, jet-surface interactions results, acoustic characteristics of multi-stream jets, and N+2 Supersonic Aircraft system studies are presented.

Modelling third harmonic ion cyclotron acceleration of deuterium beams for JET fusion product studies experiments

DEFF Research Database (Denmark)

Schneider, M.; Johnson, T.; Dumont, R.

2016-01-01

Recent JET experiments have been dedicated to the studies of fusion reactions between deuterium (D) and Helium-3 (3He) ions using neutral beam injection (NBI) in synergy with third harmonic ion cyclotron radio-frequency heating (ICRH) of the beam. This scenario generates a fast ion deuterium tail...... enhancing DD and D3He fusion reactions. Modelling and measuring the fast deuterium tail accurately is essential for quantifying the fusion products. This paper presents the modelling of the D distribution function resulting from the NBI+ICRF heating scheme, reinforced by a comparison with dedicated JET fast...

Detection Damage in Bearing System of Jet Engine Using the Vibroacoustic Method

Directory of Open Access Journals (Sweden)

Żokowski Mariusz

2017-09-01

Full Text Available The article discusses typical, operational systems for monitoring vibrations of jet engines, which constitute the propulsion of combat aircraft of the Armed Forces of the Republic of Poland. After that, the paper presents the stage of installing vibration measuring sensors in the direct area of one of the jet engine bearings, which is a support system for its rotor. The article discusses results of carried out analyses of data gathered during tests of the engine in the conditions a jet engine test bed. Results of detecting damages to the bear-ing, using sensors built in the direct area will be presented.

Prodigious degassing of a billion years of accumulated radiogenic helium at Yellowstone

Science.gov (United States)

Lowenstern, Jacob B.; Evans, William C.; Bergfeld, D.; Hunt, Andrew G.

2014-01-01

Helium is used as a critical tracer throughout the Earth sciences, where its relatively simple isotopic systematics is used to trace degassing from the mantle, to date groundwater and to time the rise of continents1. The hydrothermal system at Yellowstone National Park is famous for its high helium-3/helium-4 isotope ratio, commonly cited as evidence for a deep mantle source for the Yellowstone hotspot2. However, much of the helium emitted from this region is actually radiogenic helium-4 produced within the crust by α-decay of uranium and thorium. Here we show, by combining gas emission rates with chemistry and isotopic analyses, that crustal helium-4 emission rates from Yellowstone exceed (by orders of magnitude) any conceivable rate of generation within the crust. It seems that helium has accumulated for (at least) many hundreds of millions of years in Archaean (more than 2.5 billion years old) cratonic rocks beneath Yellowstone, only to be liberated over the past two million years by intense crustal metamorphism induced by the Yellowstone hotspot. Our results demonstrate the extremes in variability of crustal helium efflux on geologic timescales and imply crustal-scale open-system behaviour of helium in tectonically and magmatically active regions.

Plasma position and current control system enhancements for the JET ITER-like wall

Energy Technology Data Exchange (ETDEWEB)

De Tommasi, G. [Associazione EURATOM-ENEA-CREATE, Univ. di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy); Maviglia, F. [Associazione EURATOM-ENEA-CREATE, Via Claudio 21, 80125 Napoli (Italy); Neto, A.C. [Ass. EURATOM-IST, Instituto de Plasmas e Fusão Nuclear, IST, 1049-001 Lisboa (Portugal); Lomas, P.J.; McCullen, P.; Rimini, F.G. [Euratom-CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom)

2014-03-15

Highlights: • JET plasma position and current control system enhanced for the JET ITER like wall. • Vertical stabilization system enhanced to speed up its response and to withstand larger perturbations. • Improved termination management system. • Implementation of the current limit avoidance system. • Implementation of PFX-on-early-task. - Abstract: The upgrade of Joint European Torus (JET) to a new all-metal wall, the so-called ITER-like wall (ILW), has posed a set of new challenges regarding both machine operation and protection. The plasma position and current control (PPCC) system plays a crucial role in minimizing the possibility that the plasma could permanently damage the ILW. The installation of the ILW has driven a number of upgrades of the two PPCC components, namely the Vertical Stabilization (VS) system and the Shape Controller (SC). The VS system has been enhanced in order to speed up its response and to withstand larger perturbations. The SC upgrade includes three new features: an improved termination management system, the current limit avoidance system, and the PFX-on-early-task. This paper describes the PPCC upgrades listed above, focusing on the implementation issues and on the experimental results achieved during the 2011–12 JET experimental campaigns.

Dynamics of cold helium flow inside a cryoline used for large cryogenic distribution system

International Nuclear Information System (INIS)

Kumar, Uday; Jadon, Mohit; Choukekar, Ketan; Shukla, Vinit; Patel, Pratik; Kapoor, Himanshu; Shah, Nitin; Muralidhara, Srinivasa; Sarkar, Biswanath

2015-01-01

The Cryolines, which by definition transfers cryogens from the source, normally a cryogenic plant, to several systems requiring cooling at cryogenic temperature to the level of 4 K and 80 K. The operations of cryolines are normally assumed to be steady state following a cool down from room temperature to the cryogenic temperature. It is to be noted that in a distributed cryogenic system, especially in a nuclear facility such as ITER having confinement definition due to the regulatory requirements, do also attract the attention in the system design that the release from safety valves cannot be allowed inside a building. Therefore, all safety valves need to be discharged inside a confined space, which is a specific space requiring fulfillment of definition for a cryogenic line. The specificity in such cases is that such cryogenic lines will realize dynamic conditions for each release of safety valves or a combination of safety valves in terms of pressure, temperature and flow, leading to unexpected failures. Such operating scenarios also lead to serious impact on fatigue with a question mark on the reliability. Therefore, one can define such cryolines as Relief Collection Header (RCH) which collects discharged helium and transport it to the appropriate place as defined in the system design. The discharges of cold helium from safety relief discharge ports of equipment can result into significantly unsteady and compressible flow in RCH. The proper design of the RCH has to be supported by detailed dynamic of expected flow phenomena for specific cases. The paper presents the dynamics of cold helium flow inside the typical RCH that has been performed to investigate the variation in flow parameters (pressure, temperature, velocity and density) along the axis of RCH and predictions on its reliability. (author)

Development of 'popup' Langmuir probe system for the JET MkIIa divertor

International Nuclear Information System (INIS)

Davies, S.; Tellier, X.; Matthews, G.

1999-01-01

The successful operation of a 'popup' Langmuir probe system, which was installed in the JET MkIIa divertor, is described. The system utilises the ambient magnetic field in tokamak plasmas to act on a current carrying coil and pop up a rail containing Langmuir probes. Measurements were made using 'Pin-Plate' probes which, owing to their relatively large exposed area, are ideally suited for use with such a system. Details of the design, testing, measurements and potential applications of JET's 'popup' system are given. (author)

Multiwavelength Study of Powerful New Jet Activity in the Symbiotic Binary System R Aqr

Science.gov (United States)

Karovska, Margarita

2016-09-01

We propose to carry out coordinated high-spatial resolution Chandra ACIS-S and HST/WFC3 observations of R Aqr, a very active symbiotic interacting binary system. Our main goal is to study the physical characteristics of multi-scale components of the powerful jet; from near the central binary (within a few AU) to the jet-circumbinary material interaction region (2500 AU) and beyond , and especially of the recently discovered inner jet, to gain insight on early jet formation and propagation, such as jet kinematics and precession.

Multiwavelength Study of Powerful New Jet Activity in the Symbiotic System R AQR

Science.gov (United States)

Karovska, Margarita

2016-10-01

We propose to carry out coordinated high-spatial resolution Chandra ACIS-S and multiwavelength (UV-Optical) HST/WFC3 observations of R Aqr, a very active symbiotic interacting binary system. Our main goal is to study the physical characteristics of the multi-scale components of the powerful jet; from the vicinity of the central binary (within a few AU) to the jet-circumbinary material interaction region (2500 AU) and beyond, and especially of the recently discovered new component of the inner jet (likely due to recent ejection of material). Our main goal is to gain new insight on early jet formation and propagation, including jet kinematics and precession.

The Chemistry of Protostellar Jet-Disk Systems

Science.gov (United States)

Codella, Claudio

2017-11-01

The birth of a Sun-like star is a complex game played by several participants whose respective roles are not yet entirely clear. On the one hand, the star-to-be accretes matter from a collapsing envelope. The gravitational energy released in the process heats up the material surrounding the protostar, creating warm regions enriched by interstellar complex organic molecules (iCOMs, at least 6 atoms) called hot-corinos. On the other hand, the presence of angular momentum and magnetic fields leads to two consequences: (i) the formation of circumstellar disks; and (ii) substantial episodes of matter ejection, as e.g. collimated jets. Thanks to the combination of the high-sensitivities and high-angular resolu- tions provided by the advent of new telescopes such as ALMA and NOEMA, it is now possible to image in details the earliest stages of the Sun-like star formation, thus inspecting the inner ( effects connected with the accreting disk. In other words, it is time to study the protostellar jet-disk system as a whole. Several still unanswered questions can be addressed. What is the origin of the chemically enriched hot corinos: are they jet-driven shocked regions? What is the origin of the ejections: are they due to disk or stellar winds? Shocks are precious tool to attack these questions, given they enrich the gas phase with the species deposited onto the dust mantles and/or locked in the refractory dust cores. Basically, we have to deal with two kind of shocks: (i) high-velocity shocks produced by protostellar jets, and (ii) slow accretion shocks located close to the centrifugal barrier of the accretion disks. Both shocks are factories of iCOMs, which can be then efficiently used to follow both the kinematics and the chemistry of the inner protostellar systems. With this in mind, we will discuss recent results obtained in the framework of different observational campaigns at mm and sub-mm wavelengths.

Atmospheric pressure He-air plasma jet: Breakdown process and propagation phenomenon

Energy Technology Data Exchange (ETDEWEB)

Begum, Asma [Independent University, Bangladesh, School of Engineering and Computer Science, Bashundhara, Dhaka (Bangladesh); Laroussi, Mounir [Old Dominion University, Department of Electrical and Computer Engineering, Norfolk, Virginia (United States); Pervez, Mohammad Rasel [Master Mind College, Department of Physics, Dhanmondi, Dhaka (Bangladesh)

2013-06-15

In this paper He-discharge (plasma jet/bullet) in atmospheric pressure air and its progression phenomenon has been studied experimentally using ICCD camera, optical emission spectroscopy (OES) and calibrated dielectric probe measurements. The repetitive nanosecond pulse has applied to a plasma pencil to generate discharge in the helium gas channel. The discharge propagation speed was measured from the ICCD images. The axial electric field distribution in the plasma jet is inferred from the optical emission spectroscopic data and from the probe measurement. The correlation between the jet velocities, jet length with the pulse duration is established. It shows that the plasma jet is not isolated from the input voltage along its propagation path. The discharge propagation speed, the electron density and the local and average electric field distribution along the plasma jet axis predicted from the experimental results are in good agreement with the data predicted by numerical simulation of the streamer propagation presented in different literatures. The ionization phenomenon of the discharge predicts the key ionization parameters, such as speed, peak electric field in the front, and electron density. The maximum local electric field measured by OES is 95 kV/cm at 1.3 cm of the jet axis, and average EF measured by probe is 24 kV/cm at the same place of the jet. The average and local electron density estimated are in the order of 10{sup 11} cm{sup -3} and it reaches to the maximum of 10{sup 12} cm{sup -3}.

Turbulent jet erosion of a stably stratified gas layer in a nuclear reactor test containment

Energy Technology Data Exchange (ETDEWEB)

Ishay, Liel [Department of Mechanical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Bieder, Ulrich [Commissariat à l’énergie atomique et aux énergies alternatives, Centre de SACLAY DEN/SAC/DANS/DM2S/STMF/LMSF, F-91191 Gif-sur-Yvette (France); Ziskind, Gennady [Department of Mechanical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Rashkovan, Alex, E-mail: rashbgu@gmail.com [Physics Department, Nuclear Research Center Negev (NRCN), PO Box 9001, Beer-Sheva 84190 (Israel)

2015-10-15

Highlights: • We model stably stratified layer erosion by vertical turbulent round jet. • Separate effect studies are performed as a platform for choosing modeling approach. • A test performed in MISTRA facility, CEA, Saclay is modeled using Fluent and Trio-U codes. • The proposed modeling approach showed good agreement with the MISTRA facility LOWMA-3 test. - Abstract: A number of integral and separate effect experiments were performed in the last two decades for validation of containment computational tools. The main goal of these benchmark experiments was to assess the ability of turbulence models and computational fluid dynamics codes to predict hydrogen concentration distribution and steam condensation rate in a nuclear reactor containment in the course of severe accidents. It appears from the published literature that the predictive capability of the existing computational tools still needs to be improved. This work examines numerically the temporal evolution of helium concentration in the experiment called LOWMA-3, performed in the MISTRA facility of CEA-Saclay, France. In the experiment, helium is used to mimic hydrogen of a real-case accident. The aim of this separate effect experiment, where steam condensation was not involved, is to predict helium concentration field. The conditions of the experiment are such that both the momentum transport and molecular diffusion contributions to the mixing process are of the same order of magnitude (Fr ∼ 1). A commercial CFD code, Fluent, and a CEA in-house code, Trio-U, are used for flow and helium concentration fields temporal evolution prediction in the present study. The preliminary separate effect studies provide guidance to an optimal modeling approach for the LOWMA-3 experiment. Temporal evolution of helium concentration in the stratification layer is shown, and a comparison to the experiment is discussed. It is shown that correct modeling of the round jet flowfield is essential for a reliable

Turbulent jet erosion of a stably stratified gas layer in a nuclear reactor test containment

International Nuclear Information System (INIS)

Ishay, Liel; Bieder, Ulrich; Ziskind, Gennady; Rashkovan, Alex

2015-01-01

Highlights: • We model stably stratified layer erosion by vertical turbulent round jet. • Separate effect studies are performed as a platform for choosing modeling approach. • A test performed in MISTRA facility, CEA, Saclay is modeled using Fluent and Trio-U codes. • The proposed modeling approach showed good agreement with the MISTRA facility LOWMA-3 test. - Abstract: A number of integral and separate effect experiments were performed in the last two decades for validation of containment computational tools. The main goal of these benchmark experiments was to assess the ability of turbulence models and computational fluid dynamics codes to predict hydrogen concentration distribution and steam condensation rate in a nuclear reactor containment in the course of severe accidents. It appears from the published literature that the predictive capability of the existing computational tools still needs to be improved. This work examines numerically the temporal evolution of helium concentration in the experiment called LOWMA-3, performed in the MISTRA facility of CEA-Saclay, France. In the experiment, helium is used to mimic hydrogen of a real-case accident. The aim of this separate effect experiment, where steam condensation was not involved, is to predict helium concentration field. The conditions of the experiment are such that both the momentum transport and molecular diffusion contributions to the mixing process are of the same order of magnitude (Fr ∼ 1). A commercial CFD code, Fluent, and a CEA in-house code, Trio-U, are used for flow and helium concentration fields temporal evolution prediction in the present study. The preliminary separate effect studies provide guidance to an optimal modeling approach for the LOWMA-3 experiment. Temporal evolution of helium concentration in the stratification layer is shown, and a comparison to the experiment is discussed. It is shown that correct modeling of the round jet flowfield is essential for a reliable

Self-trapping of helium in metals

International Nuclear Information System (INIS)

Wilson, W.D.; Bisson, C.L.; Baskes, M.I.

1981-01-01

Atomistic calculations are presented which demonstrate that helium atoms in a metal lattice are able to cluster with each other, producing vacancies and nearby self-interstitial defects. Even a small number of helium atoms is found to be sufficient to create these large distortions. As few as five interstitial helium can spontaneously produce a lattice vacancy and nearby self-interstitial. An eight-helium-atom cluster gives rise to two such defects, and 16 helium atoms to more than five self-interstitial vacancy pairs. It was noted that the self-interstitials prefer to agglomerate on the same ''side'' of the helium cluster rather than to spread themselves out uniformly. The binding energy of each additional helium atom to these clusters increases with helium concentration and the trap is apparently unsaturable. A rate theory using these atomistic binding energies has been used to calculate the kinetics of helium-bubble nucleation and growth. The results are consistent with measurements of the properties of helium resulting from tritium decay

A Brief Study on the Ignition of the Non-Thermal Atmospheric Pressure Plasma Jet from a Double Dielectric Barrier Configured Plasma Pencil

International Nuclear Information System (INIS)

Begum, Asma; Laroussi, Mounir; Pervez, M. R.

2013-01-01

To understand the self sustained propagation of the plasma jet/bullet in air under atmospheric pressure, the ignition of the plasma jet/bullet, the plasma jet/bullet ignition point in the plasma pencil, the formation time and the formation criteria from a dielectric barrier configured plasma pencil were investigated in this study. The results were confirmed by comparing these results with the plasma jet ignition process in the plasma pencil without a dielectric barrier. Electrical, optical, and imaging techniques were used to study the formation of the plasma jet from the ignition of discharge in a double dielectric barrier configured plasma pencil. The investigation results show that the plasma jet forms at the outlet of the plasma pencil as a donut shaped discharge front because of the electric field line along the outlet's surface. It is shown that the required time for the formation of the plasma jet changes with the input voltage of the discharge. The input power calculation for the gap discharge and for the whole system shows that 56% of the average input power is used by the first gap discharge. The estimated electron density inside the gap discharge is in the order of 10 11 cm −3 . If helium is used as a feeding gas, a minimum 1.48×10 −8 C charge is required per pulse in the gap discharge to generate a plasma jet

Development of the jet-target system of the MAGIX experiment

Energy Technology Data Exchange (ETDEWEB)

Stephan, Aulenbacher [Institut fuer Kernphysik, JGU, Mainz (Germany); Collaboration: Magix/MESA-Collaboration

2016-07-01

Since the new accelerator MESA which will be built up in Mainz in the next years operates at low Energies (100 MeV), but at high beam currents (1 mA), a thin windowless target is required. Therefore the MAGIX collaboration is developing a Jet-Target. This target blasts a Gas-Jet perpendicular to the beam through the scattering chamber of MAGIX. This talk is about the development of this Target System.

Development of helium isotopic database in Japan

International Nuclear Information System (INIS)

Kusano, Tomohiro; Asamori, Koichi; Umeda, Koji

2012-09-01

We constructed “Helium Isotopic Database in Japan”, which includes isotope ratios of noble gases and chemical compositions of gas samples collected from hot springs and drinking water wells. The helium isotopes are excellent natural tracers for indicating the presence of mantle derived volatiles, because they are chemically inert and thus conserved in crustal rock-water systems. It is common knowledge that mantle degassing does not occur homogeneously over the Earth's surface. The 3 He/ 4 He ratios higher than the typical crustal values are interpreted to indicate that transfer of mantle volatiles into the crust by processes or mechanisms such as magmatic intrusion, faulting. In particular the spatial variation of helium isotope ratios could provide a valuable information to identify volcanic regions and tectonically active areas. The database was compiled geochemical data of hot spring gas etc. from 108 published papers. As a result of the data compiling, the database has 1728 helium isotopic data. A CD-ROM is attached as an appendix. (author)

Hybrid Circuit QED with Electrons on Helium

Science.gov (United States)

Yang, Ge

Electrons on helium (eHe) is a 2-dimensional system that forms naturally at the interface between superfluid helium and vacuum. It has the highest measured electron mobility, and long predicted spin coherence time. In this talk, we will first review various quantum computer architecture proposals that take advantage of these exceptional properties. In particular, we describe how electrons on helium can be combined with superconducting microwave circuits to take advantage of the recent progress in the field of circuit quantum electrodynamics (cQED). We will then demonstrate how to reliably trap electrons on these devices hours at a time, at millikelvin temperatures inside a dilution refrigerator. The coupling between the electrons and the microwave resonator exceeds 1 MHz, and can be reproduced from the design geometry using our numerical simulation. Finally, we will present our progress on isolating individual electrons in such circuits, to build single-electron quantum dots with electrons on helium.

The design, fabrication, operation and maintenance of (41) 400 H.P.-600 SCFM helium screw compressor systems (Five-year operation report)

International Nuclear Information System (INIS)

Pallaver, C.

1988-12-01

Fermi National Accelerator Laboratory (Fermilab) uses thirty-four (34) identical compressor systems connected to a common header to supply clean high pressure helium gas feeding 26 refrigerators supplying liquid helium to 777 super conducting magnets. There are seven (7) similar compressor packages in other locations. The purpose of this paper is (after five years of operation) to present all the problems, modifications and experiences associated with the design and operation of these compressor systems

Jet Joint Undertaking

International Nuclear Information System (INIS)

Keen, B.E.; O'Hara, G.W.; Pollard, I.E.

1988-07-01

The paper presents the Jet Joint Undertaking annual report 1987. A description is given of the JET and Euratom and International Fusion Programmes. The technical status of JET is outlined, including the development and improvements made to the system in 1987. The results of JET Operation in 1987 are described within the areas of: density effects, temperature improvements, energy confinement studies and other material effects. The contents also contain a summary of the future programme of JET. (U.K.)

Convective mixing in helium white dwarfs

International Nuclear Information System (INIS)

Vauclair, G.; Fontaine, G.

1979-01-01

The conditions under which convective mixing episodes take place between the helium envelopes and the underlying carbon layers in helium-rich white dwarfs are investigated. It is found that, for essentially any value of the initial helium content less than the maximum mass a helium convection zone can have, mixing does occur, and leads, in the vast majority of cases, to an almost pure carbon superficial composition. Mixing products that show only traces of carbon while retaining helium-dominated envelopes are possible only if the initial helium content is quite close to the maximum possible mass of the helium convection zone. In the presence of turbulence, this restriction could be relaxed, however, and the helium-rich lambda4670 stars may possibly be explained in this fashion

A free Hg jet system for use in a high-power target experiment

CERN Document Server

Spampinato, Philip; Gabriel, Tony A; Graves, Van; Haseroth, H; Kirk, Harold G; Lettry, Jacques; McDonald, Kirk T; Rennich, Mark; Simos, Nikolaos; Titus, P; Tsang, Thomas

2005-01-01

We describe a mercury jet system that is suitable for insertion into the 15cm diameter bore of a high-field solenoid magnet. The device features a hermetically sealed primary containment volume which is enclosed in a secondary containment system to insure isolation of mercury vapors from the remaining experimental environment. The jet diameter is 1-cm while the jet velocity will be up to 20 m/s. Optical diagnostics is incorporated into the target design to allow observation of the dispersal of the mercury as a result of interaction with a 24 GeV proton beam with up to 20 x 10

Parametric study on density stratification erosion caused by a horizontal steam jet interacting with a vertical plate obstruction

Energy Technology Data Exchange (ETDEWEB)

Paranjape, S., E-mail: Sidharth.paranjape@psi.ch; Kapulla, R., E-mail: ralf.kapulla@psi.ch; Mignot, G., E-mail: guillaume.mignot@psi.ch; Paladino, D., E-mail: domenico.paladino@psi.ch

2017-02-15

Highlights: • Helium layer breakup by horizontal steam jet impinging on vertical plate. • A small change in geometric configuration lead to a large change in flow pattern. • The functional dependence of erosion front motion on time. • Creation of a concentration stratification in adjacent vessel. - Abstract: During postulated severe accident scenarios in nuclear power plants, a hydrogen-rich layer might form at the top of the reactor containment. Various flow patterns resulting from the release of steam from the primary circuit might break the layer and redistribute hydrogen in the containment. The prediction of the gas transport during the accident requires detailed modeling of the processes involved. Advanced lumped parameter codes or computational fluid dynamics codes are used for this purpose. These codes need to be validated against experimental data obtained in large scale experimental facilities, where scale distortions are reduced. In order to obtain the required data with high spatial and temporal resolution, experiments were carried out in the PANDA facility in Switzerland as a part of OECD/HYMERES (HYdrogen Mitigation Experiments for Reactor Safety) project. The present experiments address the breakup of a layer rich in helium (used as simulant for hydrogen), under steam environment and its redistribution in two interconnected vessels (total volume of 183.3 m{sup 3}) under the action of a diffused flow resulting from the interaction of a horizontal steam jet with a vertical plate obstruction. The influence of the distance between the jet exit and the obstruction on the flow pattern was investigated. Spatial and temporal distribution of the gas concentration, the temperature and local gas velocity field were measured. It was found that a small change in the geometric configuration lead to a large change in the flow pattern. Reducing the jet-obstruction distance slowed down the helium-layer erosion process by a factor of two. Additionally, the

Single capture and transfer ionization in collisions of Clq+ projectile ions incident on helium

International Nuclear Information System (INIS)

Wong, K.L.; Ben-Itzhak, I.; Cocke, C.L.; Giese, J.P.; Richard, P.

1995-01-01

The Kansas State University linac has been used to measure the ratio of the cross sections for the processes of transfer ionization (TI) and single capture (SC) for 2 MeV/amu Cl q+ where q=7, 9, 13, 14, and 15 projectile ions incident on a helium target. The ratio was determined using a helium gas jet target by measuring coincidences between projectile-ion and recoil-ion final charge states. The σ TI /σ SC for Cl q+ were compared to measurements of bare F 9+ and hydrogenlike F 8+ and O 7+ taken at the same velocity. The ratios deviate from a q 2 scaling which is predicted in the perturbative regime. This deviation is attributed to screening by the projectile electrons for low q=7 and 9, and to the collision being non-perturbative for high q. A possible saturation effect in the ratio was observed for q similar 14. (orig.)

The JET fast central acquisition and trigger system

International Nuclear Information System (INIS)

Blackler, K.; Edwards, A.W.

1994-01-01

This paper describes a new data acquisition system at JET which uses Texas TMS320C40 parallel digital signal processors and the HELIOS parallel operating system to reduce the large amounts of experimental data produced by fast diagnostics. This unified system features a two level trigger system which performs real-time activity detection together with asynchronous event classification and selection. This provides automated data reduction during an experiment. The system's application to future fusion machines which have almost continuous operation is discussed

Optimization of a He-jet activity transport system to use at LAMPF

International Nuclear Information System (INIS)

Talbert, W.L. Jr.; Bunker, M.E.; Starner, J.W.

1986-01-01

As part of an assessment of the feasibility for a He-jet coupled on-line mass separator at LAMPF, we have studied performance characteristics of a gas activity transport system under conditions simulating those expected on the main LAMPF beam line. In experiments utilizing a side beam at LAMPF, we have measured absolute transport efficiencies, transit times, aerosol properties, and dependences on beam intensity. Further experiments with a He-jet system at the Omega West Reactor have indicated an optimum configuration of a target chamber to be placed in the LAMPF main beam. The results of these studies suggest that a He-jet activity transport system should work well at LAMPF in the 800-MeV, 1-mA proton beam that is spread over ∼40 cm 2 near the beam stop. 19 refs., 8 figs

Impurity production and transport at the JET belt limiter

International Nuclear Information System (INIS)

Pitcher, C.S.; McCracken, G.M.; Strangeby, P.C.; Toronto Univ., ON; Summers, D.D.R.

1989-01-01

Under certain operating conditions in JET the impurity content of the discharge can be high, thus reducing the fusion reaction rate through the dilution of the hydrogenic fuel. The dilution in most discharges is predominantly due to carbon impurities. In order to understand how carbon impurities are produced and transported into the plasma, detailed measurements with interference filters centered on intense spectral lines of the low ionization states of carbon (C I, C II, C III) as well as the fuel species (Dα) and helium (He I). (author) 6 refs., 4 figs

Mockup experiments to investigate the leak rate correlation between mercury and helium for the mercury target system of J-PARC

International Nuclear Information System (INIS)

Haga, Katsuhiro; Naoe, Takashi; Kogawa, Hiroyuki; Wakui, Takashi; Futakawa, Masatoshi

2009-01-01

Checking the seal performance of the mercury piping network is very important for the mercury target system operation of J-PARC, and the test method for leaks using the pressure change measurement is preferable for this purpose because it can be carried out easily and precisely by measuring the pressure change, and it is free from the risk of mercury contamination. The piping network is pressurized by helium gas. Thus, the correlation between the helium leak rate and mercury leak flow rate was investigated experimentally by carrying out leak tests for helium and mercury with an identical mockup flange model. The results showed that the mercury leak flow rates of the experimental data were lower than those of the estimated value by 64% on average. It was also found that the threshold of the helium leak rate at which good seal performance for mercury can be obtained exists between 2.18 x 10 -4 and 1.01 x 10 -2 Pa.m 3 /s. This fact confirmed the sufficient safety margin of the mercury target system against the mercury leak, where 1 x 10 -6 Pa.m 3 /s was adopted as the seal performance criterion. (author)

Characterizations of atmospheric pressure low temperature plasma jets and their applications

Science.gov (United States)

Karakas, Erdinc

2011-12-01

Atmospheric pressure low temperature plasma jets (APLTPJs) driven by short pulses have recently received great attention because of their potential in biomedical and environmental applications. This potential is due to their user-friendly features, such as low temperature, low risk of arcing, operation at atmospheric pressure, easy handheld operation, and low concentration of ozone generation. Recent experimental observations indicate that an ionization wave exists and propagates along the plasma jet. The plasma jet created by this ionization wave is not a continuous medium but rather consists of a bullet-like-structure known as "Plasma Bullet". More interestingly, these plasma bullets actually have a donut-shaped makeup. The nature of the plasma bullet is especially interesting because it propagates in the ambient air at supersonic velocities without any externally applied electric field. In this dissertation, experimental insights are reported regarding the physical and chemical characteristics of the APLTPJs. The dynamics of the plasma bullet are investigated by means of a high-speed ICCD camera. A plasma bullet propagation model based on the streamer theory is confirmed with adequate explanations. It is also found that a secondary discharge, ignited by the charge accumulation on the dielectric electrode surfaces at the end of the applied voltage, interrupts the plasma bullet propagation due to an opposing current along the ionization channel. The reason for this interesting phenomenon is explained in detail. The plasma bullet comes to an end when the helium mole fraction along the ionization channel, or applied voltage, or both, are less than some critical values. The presence of an inert gas channel in the surrounding air, such as helium or argon, has a critical role in plasma bullet formation and propagation. For this reason, a fluid dynamics study is employed by a commercially available simulation software, COMSOL, based on finite element method. Spatio

Blistering effects in neutral injection systems operated with helium and hydrogen gases: a preliminary assessment

International Nuclear Information System (INIS)

Hamilton, G.W.

1977-01-01

The practical effects of blistering and flaking in neutral injection systems are studied. These effects will soon be more important because of energy increases in systems now under development and because of their operation with fast helium ions as well as hydrogen and deuterium ions. Two main effects were studied: enhanced erosion rate and possible voltage breakdown from sharp flakes and gas emission

Ultrafast quenching of metals to liquid-helium temperatures - investigation of the low-temperature mobility of hydrogen in niobium

International Nuclear Information System (INIS)

Blanz, M.; Blocher, R.; Carstanjen, H.D.; Messer, R.; Plachke, D.; Seeger, A.

1989-01-01

A novel technique for ultrafast quenching from 300 K to 4.2 K has been developed. It employs a fast jet of liquid helium with a speed of about 10 2 m/s and allows us to quench metal samples in about 6 ms. This corresponds to a quenching rate of about 4.5x10 4 K/s, which exceeds that achievable by conventional quenching in liquid helium by more than one order of magnitude. The technique has been used for a resistometric study of the behaviour of hydrogen in niobium quenched-in from the α-phase by means of isochronal and isothermal annealing. Even in the low-temperature region below 20 K a considerable recovery of the resistivity has been found, which cannot be seen in conventional quenching experiments. (orig.)

Design and study of Engineering Test Facility - Helium Circulator

International Nuclear Information System (INIS)

Jiang Huijing; Ye Ping; Zhao Gang; Geng Yinan; Wang Jie

2015-01-01

Helium circulator is one of the key equipment of High-temperature Gas-cooled Reactor Pebble-bed Module (HTR-PM). In order to simulate most normal and accident operating conditions of helium circulator in HTR-PM, a full scale, rated flow rate and power, engineering test loop, which was called Engineering Test Facility - Helium Circulator (ETF-HC), was designed and established. Two prototypes of helium circulator, which was supported by Active Magnetic Bearing (AMB) or sealed by dry gas seals, would be tested on ETF-HC. Therefore, special interchangeable design was under consideration. ETF-HC was constructed compactly, which consisted of eleven sub-systems. In order to reduce the flow resistance of the circuit, special ducts, elbows, valves and flowmeters were selected. Two stages of heat exchange loops were designed and a helium - high pressure pure water heat exchanger was applied to ensure water wouldn't be vaporized while simulating accident conditions. Commissioning tests were carried out and operation results showed that ETF-HC meets the requirement of helium circulator operation. On this test facility, different kinds of experiments were supposed to be held, including mechanical and aerodynamic performance tests, durability tests and so on. These tests would provide the features and performance of helium circulator and verify its feasibility, availability and reliability. (author)

Jet flow analysis of liquid poison injection in a CANDU reactor using source term

International Nuclear Information System (INIS)

Chae, Kyung Myung; Choi, Hang Bok; Rhee, Bo Wook

2001-01-01

For the performance analysis of Canadian deuterium uranium (CANDU) reactor shutdown system number 2 (SDS2), a computational fluid dynamics model of poison jet flow has been developed to estimate the flow field and poison concentration formed inside the CANDU reactor calandria. As the ratio of calandria shell radius over injection nozzle hole diameter is so large (1055), it is impractical to develop a full-size model encompassing the whole calandria shell. In order to reduce the model to a manageable size, a quarter of one-pitch length segment of the shell was modeled using symmetric nature of the jet; and the injected jet was treated as a source term to avoid the modeling difficulty caused by the big difference of the hole sizes. For the analysis of an actual CANDU-6 SDS2 poison injection, the grid structure was determined based on the results of two-dimensional real- and source-jet simulations. The maximum injection velocity of the liquid poison is 27.8 m/s and the mass fraction of the poison is 8000 ppm (mg/kg). The simulation results have shown well-established jet flow field. In general, the jet develops narrowly at first but stretches rapidly. Then, the flow recirculates a little in r-x plane, while it recirculates largely in r-θ plane. As the time goes on, the adjacent jets contact each other and form a wavy front such that the whole jet develops in a plate form. his study has shown that the source term model can be effectively used for the analysis of the poison injection and the simulation result of the CANDU reactor is consistent with the model currently being used for the safety analysis. In the future, it is strongly recommended to analyze the transient (from helium tank to injection nozzle hole) of the poison injection by applying Bernoulli equation with real boundary conditions

Helium in inert matrix dispersion fuels

International Nuclear Information System (INIS)

Veen, A. van; Konings, R.J.M.; Fedorov, A.V.

2003-01-01

The behaviour of helium, an important decay product in the transmutation chains of actinides, in dispersion-type inert matrix fuels is discussed. A phenomenological description of its accumulation and release in CERCER and CERMET fuel is given. A summary of recent He-implantation studies with inert matrix metal oxides (ZrO 2 , MgAl 2 O 4 , MgO and Al 2 O 3 ) is presented. A general picture is that for high helium concentrations helium and vacancy defects form helium clusters which convert into over-pressurized bubbles. At elevated temperature helium is released from the bubbles. On some occasions thermal stable nano-cavities or nano-pores remain. On the basis of these results the consequences for helium induced swelling and helium storage in oxide matrices kept at 800-1000 deg. C will be discussed. In addition, results of He-implantation studies for metal matrices (W, Mo, Nb and V alloys) will be presented. Introduction of helium in metals at elevated temperatures leads to clustering of helium to bubbles. When operational temperatures are higher than 0.5 melting temperature, swelling and helium embrittlement might occur

Design of a power conversion system for an indirect cycle, helium cooled pebble bed reactor system

International Nuclear Information System (INIS)

Wang, C.; Ballinger, R.G.; Stahle, P.W.; Demetri, E.; Koronowski, M.

2002-01-01

A design is presented for the turbomachinery for an indirect cycle, closed, helium cooled modular pebble bed reactor system. The design makes use of current technology and will operate with an overall efficiency of 45%. The design uses an intermediate heat exchanger which isolated the reactor cycle from the turbomachinery. This design excludes radioactive fission products from the turbomachinery. This minimizes the probability of an air ingress accident and greatly simplifies maintenance. (author)

On the Dynamical Structure of the Jet System in the Disk with the Keplerian Rotation

Directory of Open Access Journals (Sweden)

Kyung-Sook Jeong

1989-06-01

Full Text Available The classical sloar wind theory proposed by Parker(1963 explains well the dynamics of the wind pheonomena such as stellar wind accretion disk. While the stellar wind system like the solar wind has the spherically symmetric wind structure, there are various jet phenomena which collimate the system into the narrow space. We can find these dynamical structures in SS433, in the optical jet of M87, and around the active galactic nulei. We present the dynamical structure of the jet system in disks, which conserves the angular momentum, with the Keplerian rotation and the strong relation between the geometrical cross section and the physical change of the jet stream on the basis of the hydrodynamic equations.

Liquid helium cooling of the MFTF superconducting magnets

International Nuclear Information System (INIS)

VanSant, J.H.; Zbasnik, J.P.

1986-09-01

During acceptance testing of the Mirror Fusion Test Facility (MFTF), we measured these tests: liquid helium heat loads and flow rates in selected magnets. We used the data from these tests to estimate helium vapor quality in the magnets so that we could determine if adequate conductor cooling conditions had occurred. We compared the measured quality and flow with estimates from a theoretical model developed for the MFTF magnets. The comparison is reasonably good, considering influences that can greatly affect these values. This paper describes the methods employed in making the measurements and developing the theoretical estimates. It also describes the helium system that maintained the magnets at required operating conditions

A 3-D model of superfluid helium suitable for numerical analysis

CERN Document Server

Darve, C; Van Sciver, S W

2009-01-01

The two-fluid description is a very successful phenomenological representation of the properties of Helium II. A 3-D model suitable for numerical analysis based on the Landau-Khalatnikov description of Helium II is proposed. In this paper we introduce a system of partial differential equations that is both complete and consistent as well as practical, to be used for a 3-D solution of the flow of Helium II. The development of a 3-D numerical model for Helium II is motivated by the need to validate experimental results obtained by observing the normal component velocity distribution in a Helium II thermal counter-flow using the Particle Image Velocimetry (PIV) technique.

A proposed neutron spectrometer system for JET

International Nuclear Information System (INIS)

Elevant, T.; Hellbom, G.; Scheffel, J.; Malmskog, S.

1979-12-01

A neutron spectrometer system is proposed primarily for measurements of ion temperature and density and ion beam energy distribution in extended fusion plasmas like e.g. in JET. Three different spectrometers are involved: time of flight, proton recoil and 3 He. Energy resolutions of a few percent both for DD and DT neutrons are provided. Six order of magnitudes in flux ranges will be covered by the system when employing multi-target systems. A neutron collimator and shielding system will be desirable in order to obtain relevant information. Due to the entire differences in energy and fluxes for DD and DT plasmas a flexible collimator-shielding system is recommended

A Universal Scaling for the Energetics of Relativistic Jets From Black Hole Systems

Science.gov (United States)

Nemmen, R. S.; Georganopoulos, M.; Guiriec, S.; Meyer, E. T.; Gehrels, N.; Sambruna, R. M.

2013-01-01

Black holes generate collimated, relativistic jets which have been observed in gamma-ray bursts (GRBs), microquasars, and at the center of some galaxies (active galactic nuclei; AGN). How jet physics scales from stellar black holes in GRBs to the supermassive ones in AGNs is still unknown. Here we show that jets produced by AGNs and GRBs exhibit the same correlation between the kinetic power carried by accelerated particles and the gamma-ray luminosity, with AGNs and GRBs lying at the low and high-luminosity ends, respectively, of the correlation. This result implies that the efficiency of energy dissipation in jets produced in black hole systems is similar over 10 orders of magnitude in jet power, establishing a physical analogy between AGN and GRBs.

Helium Leak Test for the PLS Storage Ring Chamber

International Nuclear Information System (INIS)

Choi, M. H.; Kim, H. J.; Choi, W. C.

1993-01-01

The storage ring vacuum system for the Pohang Light Source (PLS) has been designed to maintain the vacuum pressure of 10 1 0 Torr which requires UHV welding to have helium leak rate less than 1x10 1 0 Torr·L/sec. In order to develop new technique (PLS) welding technique), a prototype vacuum chamber has been welded by using Tungsten Inert Gas welding method and all the welded joints have been tested with a non-destructive method, so called helium leak detection, to investigate the vacuum tightness of the weld joints. The test was performed with a detection limit of 1x10 1 0 Torr·L/sec for helium and no detectable leaks were found for all the welded joints. Thus the performance of welding technique is proven to meet the criteria of helium leak rate required in the PLS Storage Ring. Both the principle and the procedure for the helium leak detection are also discussed

Helium-flow measurement using ultrasonic technique

International Nuclear Information System (INIS)

Sondericker, J.H.

1983-01-01

While designing cryogenic instrumentation for the Colliding Beam Accelerator (CBA) helium-distribution system it became clear that accurate measurement of mass flow of helium which varied in temperature from room to sub-cooled conditions would be difficult. Conventional venturi flow meters full scale differential pressure signal would decrease by more than an order of magnitude during cooldown causing unacceptable error at operating temperature. At sub-cooled temperatures, helium would be pumped around cooling loops by an efficient, low head pressure circulating compressor. Additional pressure drop meant more pump work was necessary to compress the fluid resulting in a higher outlet temperature. The ideal mass flowmeter for this application was one which did not add pressure drop to the system, functioned over the entire temperature range, has high resolution and delivers accurate mass flow measurement data. Ultrasonic flow measurement techniques used successfully by the process industry, seemed to meet all the necessary requirements. An extensive search for a supplier of such a device found that none of the commercial stock flowmeters were adaptable to cryogenic service so the development of the instrument was undertaken by the CBA Cryogenic Control and Instrumentation Engineering Group at BNL

Research and development for the high-temperature helium-leak detection system (Joint research). Part 2. Development of temperature sensors using optical fibre for the HTTR

Energy Technology Data Exchange (ETDEWEB)

Sakaba, Nariaki; Nakazawa, Toshio; Kawasaki, Kozo [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Urakami, Masao; Saisyu, Sadanori [Japan Atomic Power Co., Tokyo (Japan)

2003-03-01

In the second stage of the research and development for a high-temperature helium-leak detection system, the temperature sensor using optical fibres was studied. The sensor detects the helium leakage by the temperature increase surrounded optical fibre with or without heat insulator. Moreover, the applicability of high temperature equipments as the HTTR system was studied. With the sensor we detected 5.0-20.0 cm{sup 3}/s helium leakages within 60 minutes. Also it was possible to detect earlier when the leakage level is at 20.0 cm {sup 3}/s. (author)

Jet inclusive cross sections

International Nuclear Information System (INIS)

Del Duca, V.

1992-11-01

Minijet production in jet inclusive cross sections at hadron colliders, with large rapidity intervals between the tagged jets, is evaluated by using the BFKL pomeron. We describe the jet inclusive cross section for an arbitrary number of tagged jets, and show that it behaves like a system of coupled pomerons

Helium transport and exhaust studies in enhanced confinement regimes in DIII-D

International Nuclear Information System (INIS)

Wade, M.R.; Hillis, D.L.; Hogan, J.T.; Mahdavi, M.A.; Maingi, R.; West, W.P.; Burrell, K.H.; Finkenthal, D.F.; Gohil, P.; Groebner, R.J.

1995-02-01

A better understanding of helium transport in the plasma core and edge in enhanced confinement regimes is now emerging from recent experimental studies on DIII-D. Overall, the results are encouraging. Significant helium exhaust (τ* He /τ E ∼ 11) has been obtained in a diverted, ELMing H-mode plasma simultaneous with a central source of helium. Detailed analysis of the helium profile evolution indicates that the exhaust rate is limited by the exhaust efficiency of the pump (∼5%) and not by the intrinsic helium transport properties of the plasma. Perturbative helium transport studies using gas puffing have shown that D He /X eff ∼1 in all confinement regimes studied to date (including H-mode and VH-mode). Furthermore, there is no evidence of preferential accumulation of helium in any of these regimes. However, measurements in the core and pumping plenum show a significant dilution of helium as it flows from the plasma core to the pumping plenum. Such dilution could be the limiting factor in the overall removal rate of helium in a reactor system

Helium behaviour in nuclear glasses

International Nuclear Information System (INIS)

Fares, T.

2011-01-01

The present thesis focuses on the study of helium behavior in R7T7 nuclear waste glass. Helium is generated by the minor actinides alpha decays incorporated in the glass matrix. Therefore, four types of materials were used in this work. These are non radioactive R7T7 glasses saturated with helium under pressure, glasses implanted with 3 He + ions, glasses doped with curium and glasses irradiated in nuclear reactor. The study of helium solubility in saturated R7T7 glass has shown that helium atoms are inserted in the glass free volume. The results yielded a solubility of about 10 16 at. cm -3 atm. -1 . The incorporation limit of helium in this type of glass has been determined; its value amounted to about 2*10 21 at. cm -3 , corresponding to 2.5 at.%. Diffusion studies have shown that the helium migration is controlled by the single population dissolved in the glass free volume. An ideal diffusion model was used to simulate the helium release data which allowed to determine diffusion coefficients obeying to the following Arrhenius law: D = D 0 exp(-E a /kBT), where D 0 = 2.2*10 -2 and 5.4*10 -3 cm 2 s -1 and E a = 0.61 eV for the helium saturated and the curium doped glass respectively. These results reflect a thermally activated diffusion mechanism which seems to be not influenced by the glass radiation damage and helium concentrations studied in the present work (up to 8*10 19 at. g -1 , corresponding to 0.1 at.%). Characterizations of the macroscopic, structural and microstructural properties of glasses irradiated in nuclear reactor did not reveal any impact associated with the presence of helium at high concentrations. The observed modifications i.e. a swelling of 0.7 %, a decrease in hardness by 38 %, an increase between 8 and 34 % of the fracture toughness and a stabilization of the glass structure under irradiation, were attributed to the glass nuclear damage induced by the irradiation in reactor. Characterizations by SEM and TEM of R7T7 glasses implanted

Development of pop-up Langmuir probe system for the JET MkIIa divertor

International Nuclear Information System (INIS)

Davies, S.J.; Tellier, X.; Matthews, G.F.; Wilson, C.H.

1999-01-01

The successful operation of a pop-up Langmuir probe system, which was installed in the JET MkIIa divertor, is described. The system utilises the ambient magnetic field in tokamak plasmas to act on a current carrying coil and pop up a rail containing Langmuir probes. Measurements were made using pin-plate probes which, owing to their relatively large exposed area, are ideally suited for use with such a system. Details of the design, testing, measurements and potential applications of JET's pop-up system are given. (orig.)

Cooling with Superfluid Helium

Energy Technology Data Exchange (ETDEWEB)

Lebrun, P; Tavian, L [European Organization for Nuclear Research, Geneva (Switzerland)

2014-07-01

The technical properties of helium II (‘superfluid’ helium) are presented in view of its applications to the cooling of superconducting devices, particularly in particle accelerators. Cooling schemes are discussed in terms of heat transfer performance and limitations. Large-capacity refrigeration techniques below 2 K are reviewed, with regard to thermodynamic cycles as well as process machinery. Examples drawn from existing or planned projects illustrate the presentation. Keywords: superfluid helium, cryogenics.

Development of liquid poison injection system (SDS-2) for 500 MWe PHWRs

International Nuclear Information System (INIS)

Nawathe, Shirish; Umashankari, P.; Balakrishnan, Kamala; Mahajan, S.C.; Kakodkar, A.

1991-01-01

A secondary shut-down system (SDS-2) in the form of a mecahnism for introducing poison into the moderator of the PHWR is under development in Reactor Engineering Division of BARC. The system, as conceived, consists of a tank containing pressurised helium connected to poison tanks through quick opening solenoid valves. The tanks are connected to horizontal injection tubes in the calandria. On system actuation, gadolinium nitrate solution from the tanks passes to the injection tubes which have a number of holes through which the poison enters the moderator. This report details the development work being done on this poison injection system. An experimental facility was set up to measure the poison jet growth rate and the jet spread after injection, and mathematical models were developed to convert the observed jets into reactivity worth values. A description of the work and the computed results are presented. (author). 21 graphs. , 15 tabs

Design and Experiment of a Solder Paste Jetting System Driven by a Piezoelectric Stack

Directory of Open Access Journals (Sweden)

Shoudong Gu

2016-06-01

Full Text Available To compensate for the insufficiency and instability of solder paste dispensing and printing that are used in the SMT (Surface Mount Technology production process, a noncontact solder paste jetting system driven by a piezoelectric stack based on the principle of the nozzle-needle-system is introduced in this paper, in which a miniscule gap exists between the nozzle and needle during the jetting process. Here, the critical jet ejection velocity is discussed through theoretical analysis. The relations between ejection velocity and needle structure, needle velocity, and nozzle diameter were obtained by FLUENT software. Then, the prototype of the solder paste jetting system was fabricated, and the performance was verified by experiments. The effects of the gap between nozzle and needle, the driving voltage, and the nozzle diameter on the jetting performance and droplet diameter were obtained. Solder paste droplets 0.85 mm in diameter were produced when the gap between the nozzle and needle was adjusted to 10 μm, the driving voltage to 80 V, the nozzle diameter to 0.1 mm, and the variation of the droplet diameter was within ±3%.

Evaluation, Comparison and Optimization of the Compact Recuperator for the High Temperature Gas-Cooled Reactor (HTGR) Helium Turbine System

International Nuclear Information System (INIS)

Hao Haoran; Yang Xiaoyong; Wang Jie; Ye Ping; Yu Xiaoli; Zhao Gang

2014-01-01

Helium turbine system is a promising method to covert the nuclear power generated by the High Temperature Gas Cooled Reactor (HTGR) into electricity with inherent safety, compact configuration and relative high efficiency. And the recuperator is one of the key components for the HTGR helium turbine system. It is used to recover the exhaust heat out of turbine and pass it to the helium from high pressure compressor, and hence increase the cycle’s efficiency dramatically. On the other hand, the pressure drop within the recuperator will reduce the cycle efficiency, especially on low pressure side of recuperator. It is necessary to optimize the design of recuperator to achieve better performance of HTGR helium turbine system. However, this optimization has to be performed with the restriction of the size of the pressure vessel which contains the power conversion unit. This paper firstly presents an analysis to investigate the effects of flow channel geometry, recuperator’s power and size on heat transfer and pressure drop. Then the relationship between the recuperator design and system performance is established with an analytical model, followed by the evaluations of the current recuperator designs of GT-MHR, GTHTR300 and PBMR, in which several effective technical measures to optimize the recuperator are compared. Finally it is found that the most important factors for optimizing recuperator design, i.e. the cross section dimensions and tortuosity of flow channel, which can also be extended to compact intermediate heat exchangers. It turns out that a proper optimization can increase the cycle’s efficiency by 1~2 percentage, which could also raise the economy and competitiveness of future commercial HTGR plants. (author)

First experimental results with the Current Limit Avoidance System at the JET tokamak

Energy Technology Data Exchange (ETDEWEB)

De Tommasi, G. [Associazione EURATOM-ENEA-CREATE, Università di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy); Galeani, S. [Dipartimento di Informatica, Sistemi e Produzione, Università di Roma, Tor Vergata, Rome (Italy); Jachmich, S. [Association EURATOM-Belgian State, Koninklijke Militaire School - Ecole Royale Militaire, B-1000 Brussels (Belgium); Joffrin, E. [IRFM-CEA, Centre de Cadarache, 13108 Saint-paul-lez-Durance (France); Lennholm, M. [EFDA Close Support Unit, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); European Commission, B-1049 Brussels (Belgium); Lomas, P.J. [Euratom-CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Neto, A.C. [Associazione EURATOM-IST, Instituto de Plasmas e Fusao Nuclear, IST, 1049-001 Lisboa (Portugal); Maviglia, F. [Associazione EURATOM-ENEA-CREATE, Via Claudio 21, 80125 Napoli (Italy); McCullen, P. [Euratom-CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Pironti, A. [Associazione EURATOM-ENEA-CREATE, Università di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy); Rimini, F.G. [Euratom-CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Sips, A.C.C. [European Commission, B-1049 Brussels (Belgium); Varano, G.; Vitelli, R. [Dipartimento di Informatica, Sistemi e Produzione, Università di Roma, Tor Vergata, Rome (Italy); Zaccarian, L. [CNRS, LAAS, 7 Avenue du Colonel Roche, F-31400 Toulouse (France); Universitè de Toulouse, LAAS, F-31400 Toulouse (France)

2013-06-15

The Current Limit Avoidance System (CLA) has been recently deployed at the JET tokamak to avoid current saturations in the poloidal field (PF) coils when the eXtreme Shape Controller is used to control the plasma shape. In order to cope with the current saturation limits, the CLA exploits the redundancy of the PF coils system to automatically obtain almost the same plasma shape using a different combination of currents in the PF coils. In the presence of disturbances it tries to avoid the current saturations by relaxing the constraints on the plasma shape control. The CLA system has been successfully implemented on the JET tokamak and fully commissioned in 2011. This paper presents the first experimental results achieved in 2011–2012 during the restart and the ITER-like wall campaigns at JET.

Connection of a He-jet recoil transport system to an ion source

International Nuclear Information System (INIS)

Sheppard, G.A.

1977-02-01

In an effort to make non-gaseous fission products available for on-line separation and study with the TRISTAN facility, an investigation of the operational characteristics of a He-jet recoil transport system and a TRISTAN-type ion source was conducted after interfacing them with a skimmer. So that experimental results could be understood and controlled, studies of the dynamics of choked flow in a capillary and of the transport characteristics were made. Satisfactory performance of the He-jet system was obtained, but large temperature and pressure gradients thwarted early attempts to efficiently couple the He-jet to the ion source. The pressure-related difficulties have been overcome by employing a skimmer to remove extraneous gases before injection of the activities into the ion source, but efforts to conquer the temperature-related problems continue

The experience with JET's combined dc/Rf glow discharge cleaning (GDC) system

International Nuclear Information System (INIS)

Pearce, R.J.H.; Andrew, P.; Bryan, S.

1996-01-01

The JET Tokamak was fitted with four new electrodes of novel design, each powered from individual computer controlled dc and RF supplies. Details of enhancements and problems from 15 months experience with the system are outlined. Experiments were performed to assess the effect of RF on the glow discharge characteristics, and to establish stable glow at low pressure and high voltage. JET combined RF/dc glow discharge cleaning (GDC) had no significant advantages over pure dc GDC, provided highly stable dc current control was obtained. In fact, the mechanically weak electrode inductor spiral required to allow RF posed a distinct disadvantage. The electrodes were converted to simple plates, following damage caused by halo currents during Tokamak plasma disruptions. The performance of these electrodes was assessed. Future developments in the JET GDC system are outlined. (Author)

High temperature helium test rig with prestressed concrete pressure vessel

International Nuclear Information System (INIS)

Schmidl, H.

1975-10-01

The report gives a short description of the joint project prestressed concrete vessel-helium test station as there is the building up of the concrete structure, the system of instrumentation, the data processing, the development of the helium components as well as the testing programs. (author)

Helium supply demand in future years

International Nuclear Information System (INIS)

Laverick, C.

1975-01-01

Adequate helium will be available to the year 2000 AD to meet anticipated helium demands for present day applications and the development of new superconducting technologies of potential importance to the nation. It is almost certain that there will not be enough helium at acceptable financial and energy cost after the turn of the century to meet the needs of the many promising helium based technologies now under development. Serious consideration should be given to establishing priorities in development and application based upon their relative value to the country. In the first half of the next century, three ways of estimating helium demand lead to cumulative ranges of from 75 to 125 Gcf (economic study), 89 to 470 Gcf (projected national energy growth rates) and 154 to 328 Gcf (needs for new technologies). These needs contrast with estimated helium resources in natural gas after 2000 AD which may be as low as 10 or 126 Gcf depending upon how the federal helium program is managed and the nation's natural gas resources are utilized. The technological and financial return on a modest national investment in further helium storage and a rational long term helium program promises to be considerable

A MARTe based simulator for the JET Vertical Stabilization system

Energy Technology Data Exchange (ETDEWEB)

Bellizio, Teresa, E-mail: teresa.bellizio@unina.it [Associazione EURATOM-ENEA-CREATE, University di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy); De Tommasi, Gianmaria; Risoli, Nicola; Albanese, Raffaele [Associazione EURATOM-ENEA-CREATE, University di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy); Neto, Andre [Associacao EURATOM/IST, Inst. de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior, Tecnico, P-1049-001 Lisboa (Portugal)

2011-10-15

Validation by means of simulation is a crucial step when developing real-time control systems. Modeling and simulation are an essential tool since the early design phase, when the control algorithms are designed and tested. This phase is commonly carried out in off-line environments such as Matlab and Simulink. A MARTe-based simulator has been recently developed to validate the new JET Vertical Stabilization (VS) system. MARTe is the multi-thread framework used at JET to deploy hard real-time control systems. This paper presents the software architecture of the MARTe-based simulator and it shows how this tool has been effectively used to evaluate the effects of Edge Localized Modes (ELMs) on the VS system. By using the simulator it is possible to analyze different plasma configurations, extrapolating the limit of the new vertical amplifier in terms of the energy of the largest rejectable ELM.

Quantum dissipative dynamics and decoherence of dimers on helium droplets

International Nuclear Information System (INIS)

Schlesinger, Martin

2011-01-01

In this thesis, quantum dynamical simulations are performed in order to describe the vibrational motion of diatomic molecules in a highly quantum environment, so-called helium droplets. We aim to reproduce and explain experimental findings which were obtained from dimers on helium droplets. Nanometer-sized helium droplets contain several thousands of 4 He atoms. They serve as a host for embedded atoms or molecules and provide an ultracold ''refrigerator'' for them. Spectroscopy of molecules in or on these droplets reveals information on both the molecule and the helium environment. The droplets are known to be in the superfluid He II phase. Superfluidity in nanoscale systems is a steadily growing field of research. Spectra obtained from full quantum simulations for the unperturbed dimer show deviations from measurements with dimers on helium droplets. These deviations result from the influence of the helium environment on the dimer dynamics. In this work, a well-established quantum optical master equation is used in order to describe the dimer dynamics effectively. The master equation allows to describe damping fully quantum mechanically. By employing that equation in the quantum dynamical simulation, one can study the role of dissipation and decoherence in dimers on helium droplets. The effective description allows to explain experiments with Rb 2 dimers on helium droplets. Here, we identify vibrational damping and associated decoherence as the main explanation for the experimental results. The relation between decoherence and dissipation in Morse-like systems at zero temperature is studied in more detail. The dissipative model is also used to investigate experiments with K 2 dimers on helium droplets. However, by comparing numerical simulations with experimental data, one finds that further mechanisms are active. Here, a good agreement is obtained through accounting for rapid desorption of dimers. We find that decoherence occurs in the electronic manifold of the

Effect of cold atmospheric pressure He-plasma jet on DNA change and mutation

Science.gov (United States)

Yaopromsiri, C.; Yu, L. D.; Sarapirom, S.; Thopan, P.; Boonyawan, D.

2015-12-01

Cold atmospheric pressure plasma jet (CAPPJ) effect on DNA change was studied for assessment of its safety. The experiment utilized a home-developed CAPPJ using 100% helium to directly treat naked DNA plasmid pGFP (plasmid green fluorescent protein). A traversal electric field was applied to separate the plasma components and both dry and wet sample conditions were adopted to investigate various factor roles in changing DNA. Plasma species were measured by using optical emission spectroscopy. DNA topological form change was analyzed by gel electrophoresis. The plasma jet treated DNA was transferred into bacterial Escherichia coli cells for observing mutation. The results show that the He-CAPPJ could break DNA strands due to actions from charge, radicals and neutrals and potentially cause genetic modification of living cells.

Effect of cold atmospheric pressure He-plasma jet on DNA change and mutation

Energy Technology Data Exchange (ETDEWEB)

Yaopromsiri, C. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D., E-mail: yuld@thep-center.org [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Sarapirom, S. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Faculty of Science, Maejo University, Bang Khen, Chiang Mai 50290 (Thailand); Thopan, P.; Boonyawan, D. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

2015-12-15

Cold atmospheric pressure plasma jet (CAPPJ) effect on DNA change was studied for assessment of its safety. The experiment utilized a home-developed CAPPJ using 100% helium to directly treat naked DNA plasmid pGFP (plasmid green fluorescent protein). A traversal electric field was applied to separate the plasma components and both dry and wet sample conditions were adopted to investigate various factor roles in changing DNA. Plasma species were measured by using optical emission spectroscopy. DNA topological form change was analyzed by gel electrophoresis. The plasma jet treated DNA was transferred into bacterial Escherichia coli cells for observing mutation. The results show that the He-CAPPJ could break DNA strands due to actions from charge, radicals and neutrals and potentially cause genetic modification of living cells.

Helium sequestration at nanoparticle-matrix interfaces in helium + heavy ion irradiated nanostructured ferritic alloys

Energy Technology Data Exchange (ETDEWEB)

Parish, C.M., E-mail: parishcm@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Unocic, K.A.; Tan, L. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Zinkle, S.J. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); University of Tennessee, Knoxville, TN 37996 (United States); Kondo, S. [Institute of Advanced Energy, Kyoto University, Uji, Kyoto, 611-0011 (Japan); Snead, L.L. [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Hoelzer, D.T.; Katoh, Y. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

2017-01-15

We irradiated four ferritic alloys with energetic Fe and He ions: one castable nanostructured alloy (CNA) containing Ti-W-Ta-carbides, and three nanostructured ferritic alloys (NFAs). The NFAs were: 9Cr containing Y-Ti-O nanoclusters, and two Fe-12Cr-5Al NFAs containing Y-Zr-O or Y-Hf-O clusters. All four were subjected to simultaneous dual-beam Fe + He ion implantation (650 °C, ∼50 dpa, ∼15 appm He/dpa), simulating fusion-reactor conditions. Examination using scanning/transmission electron microscopy (STEM) revealed high-number-density helium bubbles of ∼8 nm, ∼10{sup 21} m{sup −3} (CNA), and of ∼3 nm, 10{sup 23} m{sup −3} (NFAs). STEM combined with multivariate statistical analysis data mining suggests that the precipitate-matrix interfaces in all alloys survived ∼50 dpa at 650 °C and serve as effective helium trapping sites. All alloys appear viable structural material candidates for fusion or advanced fission energy systems. Among these developmental alloys the NFAs appear to sequester the helium into smaller bubbles and away from the grain boundaries more effectively than the early-generation CNA.

A helium regenerative compressor

International Nuclear Information System (INIS)

Swift, W.L.; Nutt, W.E.; Sixsmith, H.

1994-01-01

This paper discusses the design and performance of a regenerative compressor that was developed primarily for use in cryogenic helium systems. The objectives for the development were to achieve acceptable efficiency in the machine using conventional motor and bearing technology while reducing the complexity of the system required to control contamination from the lubricants. A single stage compressor was built and tested. The compressor incorporates aerodynamically shaped blades on a 218 mm (8.6 inches) diameter impeller to achieve high efficiency. A gas-buffered non-contact shaft seal is used to oppose the diffusion of lubricant from the motor bearings into the cryogenic circuit. Since it is a rotating machine, the flow is continuous and steady, and the machine is very quiet. During performance testing with helium, the single stage machine has demonstrated a pressure ratio of 1.5 at a flow rate of 12 g/s with measured isothermal efficiencies in excess of 30%. This performance compares favorably with efficiencies generally achieved in oil flooded screw compressors

r-process nucleosynthesis in dynamic helium-burning environments

International Nuclear Information System (INIS)

Cowan, J.J.; Cameron, A.G.W.; Truran, J.W.

1985-01-01

The results of an extended examination of r-process nucleosynthesis in helium-burning environments are presented. Using newly calculated nuclear rates, dynamical r-process calculations have been made of thermal runaways in helium cores typical of low-mass stars and in the helium zones of stars undergoing supernova explosions. These calculations show that, for a sufficient flux of neutrons produced by the 13 C neutron source, r-process nuclei in solar proportions can be produced. The conditions required for r-process production are found to be: 10 20 --10 21 neutrons cm -3 for times of 0.01--0.1 s and neutron number densities in excess of 10 19 cm -3 for times of approx.1 s. The amount of 13 C required is found to be exceedingly high: larger than is found to occur in any current stellar evolutionary model. It is thus unlikely that these helium-burning environments are responsible for producing the bulk of the r-process elements seen in the solar system

Direct photon production and jet energy-loss in small systems

Energy Technology Data Exchange (ETDEWEB)

Shen, Chun; Park, Chanwook [Department of Physics, McGill University, 3600 University Street, Montreal, QC, H3A 2T8 (Canada); Paquet, Jean-François [Department of Physics, McGill University, 3600 University Street, Montreal, QC, H3A 2T8 (Canada); Department of Physics & Astronomy, Stony Brook University, Stony Brook, NY 11733 (United States); Denicol, Gabriel S. [Department of Physics, McGill University, 3600 University Street, Montreal, QC, H3A 2T8 (Canada); Physics Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Jeon, Sangyong; Gale, Charles [Department of Physics, McGill University, 3600 University Street, Montreal, QC, H3A 2T8 (Canada)

2016-12-15

Two types of penetrating probes, direct photon and QCD jets, are investigated in the background of a small and rapidly expanding droplet of quark-gluon plasma. The additional thermal electromagnetic radiation results in a ∼50% enhancement of the direct photons. In high multiplicity p+Pb collisions, jets can lose a sizeable fraction of their initial energy, leading to a charged hadron R{sub pA} of ∼0.8 at a transverse momentum around 10 GeV. Those two proposed measurements can help understand the apparent collective behaviour observed in small collision systems.

Backscattered Helium Spectroscopy in the Helium Ion Microscope: Principles, Resolution and Applications

NARCIS (Netherlands)

van Gastel, Raoul; Hlawacek, G.; Dutta, S.; Poelsema, Bene

2015-01-01

We demonstrate the possibilities and limitations for microstructure characterization using backscattered particles from a sharply focused helium ion beam. The interaction of helium ions with matter enables the imaging, spectroscopic characterization, as well as the nanometer scale modification of

A Precessing Jet in the CH Cyg Symbiotic System

Science.gov (United States)

Karovska, Margarita; Gaetz, Terrance J.; Carilli, Christopher L.; Hack, Warren; Raymond, John C.; Lee, Nicholas P.

2010-02-01

Jets have been detected in only a few symbiotic binaries to date, and CH Cyg is one of them. In 2001, a non-relativistic jet was detected in CH Cyg for the first time in X-rays. We carried out coordinated Chandra, Hubble Space Telescope (HST), and VLA observations in 2008 to study the propagation of this jet and its interaction with the circumbinary medium. We detected the jet with Chandra and HST and determined that the apex has expanded to the south from ~300 AU to ~1400 AU, with the shock front propagating with velocity <100 km s-1. The shock front has significantly slowed down since 2001. Unexpectedly, we also discovered a powerful jet in the NE-SW direction, in the X-ray, optical and radio. This jet has a multi-component structure, including an inner jet and a counterjet at ~170 AU, and a SW component ending in several clumps extending out to ~750 AU. The structure of the jet and the curvature of the outer portion of the SW jet suggest an episodically powered precessing jet or a continuous precessing jet with occasional mass ejections or pulses. We carried out detailed spatial mapping of the X-ray emission and correlation with the optical and radio emission. X-ray spectra were extracted from the central source, inner NE counterjet, and the brightest clump at a distance of ~500 AU from the central source. We discuss the initial results of our analyses, including the multi-component spectral fitting of the jet components and of the central source.

A PRECESSING JET IN THE CH Cyg SYMBIOTIC SYSTEM

International Nuclear Information System (INIS)

Karovska, Margarita; Gaetz, Terrance J.; Raymond, John C.; Lee, Nicholas P.; Carilli, Christopher L.; Hack, Warren

2010-01-01

Jets have been detected in only a few symbiotic binaries to date, and CH Cyg is one of them. In 2001, a non-relativistic jet was detected in CH Cyg for the first time in X-rays. We carried out coordinated Chandra, Hubble Space Telescope (HST), and VLA observations in 2008 to study the propagation of this jet and its interaction with the circumbinary medium. We detected the jet with Chandra and HST and determined that the apex has expanded to the south from ∼300 AU to ∼1400 AU, with the shock front propagating with velocity -1 . The shock front has significantly slowed down since 2001. Unexpectedly, we also discovered a powerful jet in the NE-SW direction, in the X-ray, optical and radio. This jet has a multi-component structure, including an inner jet and a counterjet at ∼170 AU, and a SW component ending in several clumps extending out to ∼750 AU. The structure of the jet and the curvature of the outer portion of the SW jet suggest an episodically powered precessing jet or a continuous precessing jet with occasional mass ejections or pulses. We carried out detailed spatial mapping of the X-ray emission and correlation with the optical and radio emission. X-ray spectra were extracted from the central source, inner NE counterjet, and the brightest clump at a distance of ∼500 AU from the central source. We discuss the initial results of our analyses, including the multi-component spectral fitting of the jet components and of the central source.

Helium turbomachinery operating experience from gas turbine power plants and test facilities

International Nuclear Information System (INIS)

McDonald, Colin F.

2012-01-01

The closed-cycle gas turbine, pioneered and deployed in Europe, is not well known in the USA. Since nuclear power plant studies currently being conducted in several countries involve the coupling of a high temperature gas-cooled nuclear reactor with a helium closed-cycle gas turbine power conversion system, the experience gained from operated helium turbomachinery is the focus of this paper. A study done as early as 1945 foresaw the use of a helium closed-cycle gas turbine coupled with a high temperature gas-cooled nuclear reactor, and some two decades later this was investigated but not implemented because of lack of technology readiness. However, the first practical use of helium as a gas turbine working fluid was recognized for cryogenic processes, and the first two small fossil-fired helium gas turbines to operate were in the USA for air liquefaction and nitrogen production facilities. In the 1970's a larger helium gas turbine plant and helium test facilities were built and operated in Germany to establish technology bases for a projected future high efficiency large nuclear gas turbine power plant concept. This review paper covers the experience gained, and the lessons learned from the operation of helium gas turbine plants and related test facilities, and puts these into perspective since over three decades have passed since they were deployed. An understanding of the many unexpected events encountered, and how the problems, some of them serious, were resolved is important to avoid them being replicated in future helium turbomachines. The valuable lessons learned in the past, in many cases the hard way, particularly from the operation in Germany of the Oberhausen II 50 MWe helium gas turbine plant, and the technical know-how gained from the formidable HHV helium turbine test facility, are viewed as being germane in the context of current helium turbomachine design work being done for future high efficiency nuclear gas turbine plant concepts. - Highlights: �

Effect of helium gas pressure on dc conduction mechanism and EMI shielding properties of nanocrystalline carbon thin films

Energy Technology Data Exchange (ETDEWEB)

Rawal, Ishpal, E-mail: rawalishpal@gmail.com [Department of Physics, Kirori Mal College, University of Delhi, Delhi 110007 (India); Panwar, O.S., E-mail: ospanwar@mail.nplindia.ernet.in [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Tripathi, R.K. [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Singh, Avanish Pratap; Dhawan, S.K. [Polymeric and Soft Materials Group, Physics Engineering of Carbon, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Srivastava, A.K. [Electron and Ion Microscopy, Sophisticated and Analytical Instruments, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India)

2015-05-05

This paper reports the effect of helium partial pressures ∼1.2 × 10{sup −5} (base pressure), 1.4 × 10{sup −4}, 8.6 × 10{sup −3} and 0.1 mbar on the variable range hopping conduction in nanocrystalline carbon thin films deposited by filtered cathodic jet carbon arc technique. High resolution transmission electron microscopy studies suggest the random distribution of nanocrystallites (∼3–7 nm) in the amorphous matrix. The DC conduction behavior of the deposited nanocrystalline films has been studied in the light of Mott's variable range hopping (VRH) model and found to obey three dimensional VRH conduction. The randomly distributed nanocrystallites in amorphous matrix may lead to change in the distribution of density of states near Fermi level and hence, the conduction behavior. The enhanced electrical conductivity of the deposited films due to the helium environment makes them suitable for electromagnetic interference shielding applications. The sample deposited at a helium partial pressure of 0.1 mbar has a value of shielding effectiveness ∼7.84 dB at 18 GHz frequency. - Highlights: • Nanocrystalline carbon thin films (NCTF) has been deposited by FCJCA technique. • Effect of helium gas pressure has been studied on the properties of NCTF. • Investigation of EMI shielding properties of NCTF has been carried out.

High-brightness high-order harmonic generation at 13 nm with a long gas jet

International Nuclear Information System (INIS)

Kim, Hyung Taek; Kim, I Jong; Lee, Dong Gun; Park, Jong Ju; Hong, Kyung Han; Nam, Chang Hee

2002-01-01

The generation of high-order harmonics is well-known method producing coherent extreme-ultraviolet radiation with pulse duration in the femtosecond regime. High-order harmonics have attracted much attention due to their unique features such as coherence, ultrashort pulse duration, and table-top scale system. Due to these unique properties, high-order harmonics have many applications of atomic and molecular spectroscopy, plasma diagnostics and solid-state physics. Bright generation of high-order harmonics is important for actual applications. Especially, the generation of strong well-collimated harmonics at 13 nm can be useful for the metrology of EUV lithography optics because of the high reflectivity of Mo-Si mirrors at this wavelength. The generation of bright high-order harmonics is rather difficult in the wavelength region below 15nm. Though argon and xenon gases have large conversion efficiency, harmonic generation from these gases is restricted to wavelengths over 20 nm due to low ionization potential. Hence, we choose neon for the harmonic generation around 13 nm; it has larger conversion efficiency than helium and higher ionization potential than argon. In this experiment, we have observed enhanced harmonic generation efficiency and low beam divergence of high-order harmonics from a elongated neon gas jet by the enhancement of laser propagation in an elongated gas jet. A uniform plasma column was produced when the gas jet was exposed to converging laser pulses.

PG-100 helium loop in the MR reactor

International Nuclear Information System (INIS)

Ponomarev-Stepnoj, N.N.; Yakovlev, V.V.; Tikhonov, N.I.

1983-01-01

Main systems and production equipment units of PG-100 helium loop in the MR reactor are described. Possible long-term synchronizing operation of loop and reactor as well as possibility of carrying out life-time tests of spherical fuel elements and materials are shown. Serviceability of spherical fuel elements under conditions similar to the ones of HTGR-50 operation as well as high serviceability of cleanup system accepted for HTGR are verified. Due to low radiation dose the loop is operated without limits, helium losses in the loop don't exceed 0.5%/24 h, taking account of experimental gas sampling

HeREF-2003: Helium Refrigeration Techniques

CERN Multimedia

2003-01-01

CERN Technical Training 2003: Learning for the LHC ! Theory, Technology, Maintenance and Control of Helium Refrigerators HeREF-2003 is a course in the framework of the 2002 Technical Training Programme, that will provide a complete introduction to Helium refrigeration, with a practical approach to theory, technology, maintenance and control of Helium refrigeration installations. Theoretical aspects and equations will be limited to a minimum. HeREF-2003 targets an audience of technicians and operators of Helium refrigeration plants at CERN, as well as physicists and engineers needing an overview of current Helium refrigeration techniques. HeREF-2003 will address, among other, issues related to component technology, installation maintenance, process control and Helium purity. A commented visit to a couple of CERN Helium refrigeration or liquefaction plants will also take place. Duration: 7 half days (4 mornings and 3 afternoons), 6-10 October, 2003 Cost per participant: 500.- CHF Language: Bilingual English...

HeREF-2003 : Helium Refrigeration Techniques

CERN Multimedia

2003-01-01

CERN Technical Training 2003: Learning for the LHC ! Theory, Technology, Maintenance and Control of Helium Refrigerators HeREF-2003 is a course in the framework of the 2002 Technical Training Programme, that will provide a complete introduction to Helium refrigeration, with a practical approach to theory, technology, maintenance and control of Helium refrigeration installations. Theoretical aspects and equations will be limited to a minimum. HeREF-2003 targets an audience of technicians and operators of Helium refrigeration plants at CERN, as well as physicists and engineers needing an overview of current Helium refrigeration techniques. HeREF-2003 will address, among other, issues related to component technology, installation maintenance, process control and Helium purity. A commented visit to a couple of CERN Helium refrigeration or liquefaction plants will also take place. • Duration: 7 half days (4 mornings and 3 afternoons), 6-10 October, 2003 • Cost per participant: 500.- CHF
...

Assessing the feasibility of a high-temperature, helium-cooled vacuum vessel and first wall for the Vulcan tokamak conceptual design

International Nuclear Information System (INIS)

Barnard, H.S.; Hartwig, Z.S.; Olynyk, G.M.; Payne, J.E.

2012-01-01

The Vulcan conceptual design (R = 1.2 m, a = 0.3 m, B 0 = 7 T), a compact, steady-state tokamak for plasma–material interaction (PMI) science, must incorporate a vacuum vessel capable of operating at 1000 K in order to replicate the temperature-dependent physical chemistry that will govern PMI in a reactor. In addition, the Vulcan divertor must be capable of handling steady-state heat fluxes up to 10 MW m −2 so that integrated materials testing can be performed under reactor-relevant conditions. A conceptual design scoping study has been performed to assess the challenges involved in achieving such a configuration. The Vulcan vacuum system comprises an inner, primary vacuum vessel that is thermally and mechanically isolated from the outer, secondary vacuum vessel by a 10 cm vacuum gap. The thermal isolation minimizes heat conduction between the high-temperature helium-cooled primary vessel and the water-cooled secondary vessel. The mechanical isolation allows for thermal expansion and enables vertical removal of the primary vessel for maintenance or replacement. Access to the primary vessel for diagnostics, lower hybrid waveguides, and helium coolant is achieved through ∼1 m long intra-vessel pipes to minimize temperature gradients and is shown to be commensurate with the available port space in Vulcan. The isolated primary vacuum vessel is shown to be mechanically feasible and robust to plasma disruptions with analytic calculations and finite element analyses. Heat removal in the first wall and divertor, coupled with the ability to perform in situ maintenance and replacement of divertor components for scientific purposes, is achieved by combining existing helium-cooled techniques with innovative mechanical attachments of plasma facing components, either in plate-type helium-cooled modules or independently bolted, helium-jet impingement-cooled tiles. The vacuum vessel and first wall design enables a wide range of potential PFC materials and configurations to

A new Disruption Mitigation System for deuterium–tritium operation at JET

Energy Technology Data Exchange (ETDEWEB)

Kruezi, Uron, E-mail: uron.kruezi@ccfe.ac.uk [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Jachmich, Stefan [Laboratory for Plasma Physic, ERM/KMS, B-1000 Brussels (Belgium); Koslowski, Hans Rudolf [Forschungszentrum Jülich GmbH, IEK-4, 52425 Jülich (Germany); Lehnen, Michael [ITER Organization, Route de Vinon-sur-Verdon, CS90046, 13067 St. Paul Lez Durance Cedex (France); Brezinsek, Sebastijan [Forschungszentrum Jülich GmbH, IEK-4, 52425 Jülich (Germany); Matthews, Guy [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

2015-10-15

Highlights: • A Disruption Mitigation System based on massive gas injections has been designed. • The DMS has been installed at the JET-tokamak for routine machine protection. • The DMS is capable of a throughput of up to 4.6 kPa m{sup 3}. • The new DMS is compatible with the deuterium–tritium operation at JET. - Abstract: Disruptions, the fast accidental losses of plasma current and stored energy in tokamaks, represent a significant risk to the mechanical structure as well as the plasma facing components of reactor-scale fusion facilities like ITER. At JET, the tokamak experiment closest to ITER in terms of operating parameters and size, massive gas injection has been established as a disruption mitigation method. As a “last resort” measure it reduces thermal and electromagnetic loads during disruptions which can potentially have a serious impact on the beryllium and tungsten plasma-facing materials of the main chamber and divertor. For the planned deuterium–tritium experiments, a new Disruption Mitigation System (DMS) has been designed and installed and is presented in this article. The new DMS at JET consists of an all metal gate valve compatible with gas injections, a fast high pressure eddy current driven valve, a high voltage power supply and a gas handling system providing six supply lines for pure and mixed noble and flammable gases (Ar, Ne, Kr, D{sub 2}, etc.). The valve throughput varies with the injection pressure and gas type (efficiency – injected/charged gas 50–97%); the maximum injected amount of gas is approximately 4.6 kPa m{sup 3} (at maximum system pressure of 5.0 MPa).

A new Disruption Mitigation System for deuterium–tritium operation at JET

International Nuclear Information System (INIS)

Kruezi, Uron; Jachmich, Stefan; Koslowski, Hans Rudolf; Lehnen, Michael; Brezinsek, Sebastijan; Matthews, Guy

2015-01-01

Highlights: • A Disruption Mitigation System based on massive gas injections has been designed. • The DMS has been installed at the JET-tokamak for routine machine protection. • The DMS is capable of a throughput of up to 4.6 kPa m"3. • The new DMS is compatible with the deuterium–tritium operation at JET. - Abstract: Disruptions, the fast accidental losses of plasma current and stored energy in tokamaks, represent a significant risk to the mechanical structure as well as the plasma facing components of reactor-scale fusion facilities like ITER. At JET, the tokamak experiment closest to ITER in terms of operating parameters and size, massive gas injection has been established as a disruption mitigation method. As a “last resort” measure it reduces thermal and electromagnetic loads during disruptions which can potentially have a serious impact on the beryllium and tungsten plasma-facing materials of the main chamber and divertor. For the planned deuterium–tritium experiments, a new Disruption Mitigation System (DMS) has been designed and installed and is presented in this article. The new DMS at JET consists of an all metal gate valve compatible with gas injections, a fast high pressure eddy current driven valve, a high voltage power supply and a gas handling system providing six supply lines for pure and mixed noble and flammable gases (Ar, Ne, Kr, D_2, etc.). The valve throughput varies with the injection pressure and gas type (efficiency – injected/charged gas 50–97%); the maximum injected amount of gas is approximately 4.6 kPa m"3 (at maximum system pressure of 5.0 MPa).

Jet observables without jet algorithms

Energy Technology Data Exchange (ETDEWEB)

Bertolini, Daniele; Chan, Tucker; Thaler, Jesse [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States)

2014-04-02

We introduce a new class of event shapes to characterize the jet-like structure of an event. Like traditional event shapes, our observables are infrared/collinear safe and involve a sum over all hadrons in an event, but like a jet clustering algorithm, they incorporate a jet radius parameter and a transverse momentum cut. Three of the ubiquitous jet-based observables — jet multiplicity, summed scalar transverse momentum, and missing transverse momentum — have event shape counterparts that are closely correlated with their jet-based cousins. Due to their “local” computational structure, these jet-like event shapes could potentially be used for trigger-level event selection at the LHC. Intriguingly, the jet multiplicity event shape typically takes on non-integer values, highlighting the inherent ambiguity in defining jets. By inverting jet multiplicity, we show how to characterize the transverse momentum of the n-th hardest jet without actually finding the constituents of that jet. Since many physics applications do require knowledge about the jet constituents, we also build a hybrid event shape that incorporates (local) jet clustering information. As a straightforward application of our general technique, we derive an event-shape version of jet trimming, allowing event-wide jet grooming without explicit jet identification. Finally, we briefly mention possible applications of our method for jet substructure studies.

Helium localization around the microscopic impurities embedded to liquid helium

International Nuclear Information System (INIS)

Gordon, E.B.; Shestakov, A.F.

2000-01-01

The structure and properties of the environment round the impurity atoms (Im) embedded in liquid helium are considered. It is shown that there are two qualitatively different types of structure of the He atom layer next to Im - attraction and repulsion structures. For the center attraction structure (strong Im-He interaction) the Im-He separation is longer than the equilibrium one for the pair Im-He potential, and the density and localization of He atoms are higher than in the bulk. It this case the He atom content in the layer, n, is almost independent of applied pressure. In the repulsion structure realized for alkaline metal atoms the Im-He separation is shorter than the equilibrium one and the density is lower than in the helium bulk. At T approx 1 K occupied are several states with different n and their energies differ only by approx 0.1 K, an increase in pressure resulting in a considerable reduction of n. The optical and EPR spectra of the atoms embedded to liquid and solid helium are interpreted on the basis of the analysis carried out. A simple model is proposed to evaluate the helium surroundings characteristics from the experimental pressure dependences of atomic line shifts in the absorption and emission spectra. The attraction structures in 3 He - 4 He mixtures are suggested to be highly enriched by 4 He atoms which the repulsion structures - by 3 He atoms. a possibility for existence of phase transitions in helium shells surrounding impurity atoms is considered

Experimental study of elliptical jet from supercritical to subcritical conditions using planar laser induced fluorescence

Energy Technology Data Exchange (ETDEWEB)

Muthukumaran, C. K.; Vaidyanathan, Aravind, E-mail: aravind7@iist.ac.in [Department of Aerospace Engineering, Indian Institute of Space Science and Technology, Trivandrum, Kerala 695547 (India)

2015-03-15

The study of fluid jet dynamics at supercritical conditions involves strong coupling between fluid dynamic and thermodynamic phenomena. Beyond the critical point, the liquid-vapor coexistence ceases to exist, and the fluid exists as a single phase known as supercritical fluid with its properties that are entirely different from liquids and gases. At the critical point, the liquids do not possess surface tension and latent heat of evaporation. Around the critical point, the fluid undergoes large changes in density and possesses thermodynamic anomaly like enhancement in thermal conductivity and specific heat. In the present work, the transition of the supercritical and near-critical elliptical jet into subcritical as well as supercritical environment is investigated experimentally with nitrogen and helium as the surrounding environment. Under atmospheric condition, a liquid jet injected from the elliptical orifice exhibits axis switching phenomena. As the injection temperature increases, the axis switching length also increases. Beyond the critical temperature, the axis switching is not observed. The investigation also revealed that pressure plays a major role in determining the thermodynamic transition of the elliptical jet only for the case of supercritical jet injected into subcritical chamber conditions. At larger pressures, the supercritical jet undergoes disintegration and formation of droplets in the subcritical environment is observed. However, for supercritical jet injection into supercritical environment, the gas-gas like mixing behavior is observed.

Experimental study of elliptical jet from supercritical to subcritical conditions using planar laser induced fluorescence

International Nuclear Information System (INIS)

Muthukumaran, C. K.; Vaidyanathan, Aravind

2015-01-01

The study of fluid jet dynamics at supercritical conditions involves strong coupling between fluid dynamic and thermodynamic phenomena. Beyond the critical point, the liquid-vapor coexistence ceases to exist, and the fluid exists as a single phase known as supercritical fluid with its properties that are entirely different from liquids and gases. At the critical point, the liquids do not possess surface tension and latent heat of evaporation. Around the critical point, the fluid undergoes large changes in density and possesses thermodynamic anomaly like enhancement in thermal conductivity and specific heat. In the present work, the transition of the supercritical and near-critical elliptical jet into subcritical as well as supercritical environment is investigated experimentally with nitrogen and helium as the surrounding environment. Under atmospheric condition, a liquid jet injected from the elliptical orifice exhibits axis switching phenomena. As the injection temperature increases, the axis switching length also increases. Beyond the critical temperature, the axis switching is not observed. The investigation also revealed that pressure plays a major role in determining the thermodynamic transition of the elliptical jet only for the case of supercritical jet injected into subcritical chamber conditions. At larger pressures, the supercritical jet undergoes disintegration and formation of droplets in the subcritical environment is observed. However, for supercritical jet injection into supercritical environment, the gas-gas like mixing behavior is observed

Diagnostics of helium plasma by collisional-radiative modeling and optical emission spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Lee, Wonwook; Kwon, Duck-Hee [KAERI, Daejeon (Korea, Republic of)

2015-05-15

Optical diagnostics for the electron temperature (T{sub e}) and the electron density (n{sub e}) of fusion plasma is important for understanding and controlling the edge and the divertor plasmas in tokamak. Since the line intensity ratio method using the collisional-radiative modeling and OES (optical emission spectroscopy) is simple and does not disturb the plasma, many fusion devices with TEXTOR, JET, JT-60U, LHD, and so on, have employed the line intensity ratio method as a basic diagnostic tool for neutral helium (He I). The accuracy of the line intensity ratio method depends on the reliability of the cross sections and rate coefficients. We performed state-of-the-art R-matrix calculations including couplings up to n=7 states and the distorted wave (DW) calculations for the electron-impact excitation (EIE) cross sections of He I using the flexible atomic code (FAC). The collisional-radiative model for He I was constructed using the calculated the cross sections. The helium collisional-radiative model for He I was constructed to diagnose the electron temperature and the electron density of the plasma. The electron temperature and density were determined by using the line intensity ratio method.

Functional Analysis of the Distribution Box of the KSTAR Helium Refrigerator

International Nuclear Information System (INIS)

Chang, H. S.; Kim, Y. S.; Bak, J. S.

2005-01-01

KSTAR (Korea Superconducting Tokamak Advanced Research) is a tokamak device with 30 superconducting (SC) magnet coils. The main duty of the KSTAR helium refrigerator is to keep all cold components of KSTAR (SC magnet coils, magnet structures, SC bus-lines, current lead system, and thermal shields) at suitable temperatures in order to operate the SC magnet coils consistent with the operation scenario of KSTAR. A distribution box (D/B) which is equipped with helium-property-measuring sensors, cryogenic valves (CV's), cryogenic circulators, and heat exchangers (HX's) submerged in a huge liquid helium (LHe) bath (thermal damper), intervenes the cryogenic helium via cryogenic transfer lines (TL's) between the refrigerator cold box (C/B) and the KSTAR cold components. The major functions of the D/B can be classified as listed below: i) Supplying the proper cryogen to the respective cold components of KSTAR during various operation modes (including the idle mode). ii) Cool/re-cool down of the KSTAR cold components from any temperature down to their operating cryogenic temperature within the constraints of time and temperature difference between the components. iii) Protection of the KSTAR cold components and refrigerator from damaging in case of probable abnormal events. iv) Simulation of the temporal variation of the thermal load and pressure drops occurring in the KSTAR cold components to pre-commission the refrigerator and test the cryogenic circulators. v) SC coil/bus-line cable-in-conduit conductor (CICC) cleaning. Since the helium flow in the thermal shields (TS's) is rather routine and the current lead (CL) system has its own helium distribution system, in this proceeding mainly the supercritical helium (SHe) circuits of the SC magnets and bus-lines will be discussed

Test of a cryogenic helium pump

International Nuclear Information System (INIS)

Lue, J.W.; Miller, J.R.; Walstrom, P.L.; Herz, W.

1981-01-01

The design of a cryogenic helium pump for circulating liquid helium in a magnet and the design of a test loop for measuring the pump performance in terms of mass flow vs pump head at various pump speeds are described. A commercial cryogenic helium pump was tested successfully. Despite flaws in the demountable connections, the piston pump itself has performed satisfactorily. A helium pump of this type is suitable for the use of flowing supercritical helium through Internally Cooled Superconductor (ICS) magnets. It has pumped supercritical helium up to 7.5 atm with a pump head up to 2.8 atm. The maximum mass flow rate obtained was about 16 g/s. Performance of the pump was degraded at lower pumping speeds

Radiation and gas conduction heat transport across a helium dewer multilayer insulation system

Energy Technology Data Exchange (ETDEWEB)

Green, M.A. [Lawrence Berkeley Lab., CA (United States)

1995-02-01

This report describes a method for calculating mixed heat transfer through the multilayer insulation used to insulated a 4K liquid helium cryostat. The method described permits one to estimate the insulation potential for a multilayer insulation system from first principles. The heat transfer regimes included are: radiation, conduction by free molecule gas conduction, and conduction through continuum gas conduction. Heat transfer in the transition region between the two gas conduction regimes is also included.

Cryopumping of deuterium hydrogen and helium mixtures on smooth 4.2 K surfaces

International Nuclear Information System (INIS)

Chou, T.S.; Halama, H.J.

1977-01-01

The large quantities of deuterium and hydrogen to be pumped in a fusion reactor and its subsystems favor cryopumping over other pumping methods. Cryogen consumption and the operating pressure will not only depend on the gas to be pumped, but also on the amount of helium gas present in the system. In fact, residual helium pressure between pulses will determine the power dissipation of the pump, and hence, influence the choice of cryocondensation or cryosorption. In this paper we will present the results of our studies on (1) cryotrapping of helium in thick D 2 and H 2 films and hydrogen in D 2 films at 4.2 K; (2) diffusion of He and H 2 from D 2 films; (3) steady-state liquid helium consumption; (4) liquid helium consumption as a function of D 2 and H 2 fluxes being pumped; (5) liquid helium consumption as a function of He partial pressure in the system. Finally, these measurements will suggest maximum permissible He to D 2 and He to H 2 ratios in a cryocondensation pump

First Study of Helium Gas Purification System as Primary Coolant of Co-Generation Reactor

International Nuclear Information System (INIS)

Piping Supriatna

2009-01-01

The technological progress of NPP Generation-I on 1950’s, Generation-II, Generation-III recently on going, and Generation-IV which will be implemented on next year 2025, concept of nuclear power technology implementation not only for generate electrical energy, but also for other application which called cogeneration reactor. Commonly the type of this reactor is High Temperature Reactor (HTR), which have other capabilities like Hydrogen production, desalination, Enhanced Oil Recovery (EOR), etc. The cogeneration reactor (HTR) produce thermal output higher than commonly Nuclear Power Plant, and need special Heat Exchanger with helium gas as coolant. In order to preserve heat transfer with high efficiency, constant purity of the gas must be maintained as well as possible, especially contamination from its impurities. In this report has been done study for design concept of HTR primary coolant gas purification system, including methodology by sampling He gas from Primary Coolant and purification by using Physical Helium Splitting Membrane. The examination has been designed in physical simulator by using heater as reactor core. The result of study show that the of Primary Coolant Gas Purification System is enable to be implemented on cogeneration reactor. (author)

Post-giant evolution of helium stars

International Nuclear Information System (INIS)

Schoenberner, D.

1977-01-01

Extremely hydrogen deficient stars (helium stars and R Coronae Borealis variables) are considered to be remnants of double shell source stars (of the asymptotic giant branch). The evolution of stars with a condensed C/O-core and a helium envelope is followed numerically from the red giant stage to the white dwarf domain, crossing the regions of R CrB- and helium stars (so far analyzed). They have typically masses M/M(sun) = 0.7 and luminosities log L/L(sun) = 4.1. The time for crossing the helium star domain is some 10 3 years. The corresponding times in the R CrB-region amounts up to several 10 4 years. The lower limit of the death rate of helium stars is estimated to be 4 x 10 -14 pc -3 yr -1 . This value is only a factor of ten lower than the birth rate of all non-DA white dwarfs. It is therefore possible that the helium stars are the precursors of helium rich white dwarfs. As a consequence, a significant fraction of all stars which end their lives as white dwarfs should pass through the helium star phase. (orig.) [de

New helium sniffing device for locating very fine leaks

International Nuclear Information System (INIS)

Murakami, Y.; Shimomura, Y.; Abe, T.; Obara, K.

1984-01-01

A new helium sniffing method for leak checking large vacuum vessels is described. The low sensitivity problem of the conventional helium sniffing method has been overcome by increasing the gas draw rate from around leaks into the detector up to about 0.1 Pa m 3 /s. The devised system consists of a flexible stainless steel capillary tube 0.6 mm i.d. and 10 m long, a sorption pump using molecular sieve, and a helium leak detector in series. This method is particularly useful for locating very fine leaks down to 10 -11 Pa m 3 /s. Relevant theoretical considerations and experimental results are presented

Liquid helium plant in Dubna

International Nuclear Information System (INIS)

Agapov, N.N.; Baldin, A.M.; Kovalenko, A.D.

1995-01-01

The liquid-helium cooling capacity installed at the Laboratory of High Energies is about 5 kw at a 4.5 K temperature level. It is provided with four industrial helium liquefiers of 1.6 kw/4.5 K each. They have been made by the Russian enterprise NPO GELYMASH and upgraded by the specialists of the Laboratory. The first one was put into operation in 1980, the two others in 1991, and the last one is under commissioning. The development of the LHE cryoplant was concerned with the construction of the new superconducting accelerator Nuclotron aimed to accelerate nuclei and heavy ions up to energies of 6 GeV/u. The first test run at the Nuclotron was carried out in March 1993, and the total running time has been about 2000 hours up to now. Since 1992 the cryoplant has been intensively used by the users outside the Laboratory. More than a million liters of liquid helium was provided in 1993 for such users. The reliability of the cryoplant system was as high as 98 percent for 4500 hours of operation in 1993-1994. 7 refs., 4 figs., 1 tab

Small machinery for pumping and compressing helium near 40K

International Nuclear Information System (INIS)

Swift, W.L.; Sixsmith, H.

1984-01-01

There is a significant need for small, reliable pumps and compressors suitable for circulating helium at temperatures near 4 0 K. Most pumps or compressors which have been developed to data for these applications are designed for relatively limited use. They are generally used in laboratory environments where life requirements for the experiments may be relatively short, being of the order of several hundred hours. In recent years, several applications have been identified where pumps or compressors (at liquid helium temperatures) must have high reliability if they are to be used successfully. These applications include liquid helium circulation systems through superconducting magnets and transmission lines, and cold compression applications where the compressor is used as a vacuum pump to lower the temperature of a liquid helium bath. This paper discusses the technical considerations which must be taken into account in the design and development of machinery to meet these needs. The design of a centrifugal machine which can act as a helium pump or compressor is presented

The JET real-time plasma-wall load monitoring system

International Nuclear Information System (INIS)

Valcárcel, D.F.; Alves, D.; Card, P.; Carvalho, B.B.; Devaux, S.; Felton, R.; Goodyear, A.; Lomas, P.J.; Maviglia, F.; McCullen, P.; Reux, C.; Rimini, F.; Stephen, A.; Zabeo, L.

2014-01-01

Highlights: • The paper describes the JET real-time system monitoring the first-wall plasma loads. • It presents the motivation, physics basis, design and implementation of the system. • It also presents the integration in the JET CODAS. • Operational results are presented. - Abstract: In the past, the Joint European Torus (JET) has operated with a first-wall composed of Carbon Fibre Composite (CFC) tiles. The thermal properties of the wall were monitored in real-time during plasma operations by the WALLS system. This software routinely performed model-based thermal calculations of the divertor and Inner Wall Guard Limiter (IWGL) tiles calculating bulk temperatures and strike-point positions as well as raising alarms when these were beyond operational limits. Operation with the new ITER-like wall presents a whole new set of challenges regarding machine protection. One example relates to the new beryllium limiter tiles with a melting point of 1278 °C, which can be achieved during a plasma discharge well before the bulk temperature rises to this value. This requires new and accurate power deposition and thermal diffusion models. New systems were deployed for safe operation with the new wall: the Real-time Protection Sequencer (RTPS) and the Vessel Thermal Map (VTM). The former allows for a coordinated stop of the pulse and the latter uses the surface temperature map, measured by infra-red (IR) cameras, to raise alarms in case of hot-spots. Integration of WALLS with these systems is required as RTPS responds to raised alarms and VTM, the primary protection system for the ITER-like wall, can use WALLS as a vessel temperature provider. This paper presents the engineering design, implementation and results of WALLS towards D-T operation, where it will act as a primary protection system when the IR cameras are blinded by the fusion reaction neutrons. The first operational results, with emphasis on its performance, are also presented

The JET real-time plasma-wall load monitoring system

Energy Technology Data Exchange (ETDEWEB)

Valcárcel, D.F., E-mail: daniel.valcarcel@ipfn.ist.utl.pt [Associação EURATOM/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, P-1049-001 Lisboa (Portugal); Alves, D. [Associação EURATOM/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, P-1049-001 Lisboa (Portugal); Card, P. [Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Carvalho, B.B. [Associação EURATOM/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, P-1049-001 Lisboa (Portugal); Devaux, S. [Max-Planck-Institut für Plasmaphysik, EURATOM-Assoziation, D-85748 Garching (Germany); Felton, R.; Goodyear, A.; Lomas, P.J. [Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Maviglia, F. [Associazione EURATOM-ENEA-CREATE, Univ. di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy); McCullen, P. [Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Reux, C. [Ecole Polytechnique, LPP, CNRS UMR 7648, 91128 Palaiseau (France); Rimini, F.; Stephen, A. [Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Zabeo, L. [ITER Organization, Route de Vinon sur Verdon, 13115 St., Paul Lez Durance (France); and others

2014-03-15

Highlights: • The paper describes the JET real-time system monitoring the first-wall plasma loads. • It presents the motivation, physics basis, design and implementation of the system. • It also presents the integration in the JET CODAS. • Operational results are presented. - Abstract: In the past, the Joint European Torus (JET) has operated with a first-wall composed of Carbon Fibre Composite (CFC) tiles. The thermal properties of the wall were monitored in real-time during plasma operations by the WALLS system. This software routinely performed model-based thermal calculations of the divertor and Inner Wall Guard Limiter (IWGL) tiles calculating bulk temperatures and strike-point positions as well as raising alarms when these were beyond operational limits. Operation with the new ITER-like wall presents a whole new set of challenges regarding machine protection. One example relates to the new beryllium limiter tiles with a melting point of 1278 °C, which can be achieved during a plasma discharge well before the bulk temperature rises to this value. This requires new and accurate power deposition and thermal diffusion models. New systems were deployed for safe operation with the new wall: the Real-time Protection Sequencer (RTPS) and the Vessel Thermal Map (VTM). The former allows for a coordinated stop of the pulse and the latter uses the surface temperature map, measured by infra-red (IR) cameras, to raise alarms in case of hot-spots. Integration of WALLS with these systems is required as RTPS responds to raised alarms and VTM, the primary protection system for the ITER-like wall, can use WALLS as a vessel temperature provider. This paper presents the engineering design, implementation and results of WALLS towards D-T operation, where it will act as a primary protection system when the IR cameras are blinded by the fusion reaction neutrons. The first operational results, with emphasis on its performance, are also presented.

The hydraulic jump and ripples in liquid helium

International Nuclear Information System (INIS)

Rolley, E.; Guthmann, C.; Pettersen, M.S.

2007-01-01

We have studied the characteristics of the circular hydraulic jump using liquid helium. Surprisingly, the radius of the jump does not change at the superfluid transition. We think that the flow is still dissipative below the lambda point because the velocity exceeds the critical one. The jump radius R j is compared with various models. In our parameter range, we find that the jump can be treated as a shock, and that capillary effects are important. Below the superfluid transition, we observed a standing capillary wave between the impact of the jet and the jump. Assuming that the superfluid flow can be described with an effective viscosity, we calculate the wave vector and thus obtain the value of the liquid thickness, which is in reasonable agreement with predictions. However, the spatial variation of the wave amplitude depends much more strongly on temperature than we calculate

THE RADIO JET ASSOCIATED WITH THE MULTIPLE V380 ORI SYSTEM

Energy Technology Data Exchange (ETDEWEB)

Rodríguez, Luis F.; Yam, J. Omar; Carrasco-González, Carlos [Instituto de Radioastronomía y Astrofísica, UNAM, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Michoacán, México (Mexico); Anglada, Guillem [Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía, s/n, E-18008, Granada (Spain); Trejo, Alfonso, E-mail: l.rodriguez@crya.unam.mx [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China)

2016-10-01

The giant Herbig–Haro object 222 extends over ∼6′ in the plane of the sky, with a bow shock morphology. The identification of its exciting source has remained uncertain over the years. A non-thermal radio source located at the core of the shock structure was proposed to be the exciting source. However, Very Large Array studies showed that the radio source has a clear morphology of radio galaxy and a lack of flux variations or proper motions, favoring an extragalactic origin. Recently, an optical–IR study proposed that this giant HH object is driven by the multiple stellar system V380 Ori, located about 23′ to the SE of HH 222. The exciting sources of HH systems are usually detected as weak free–free emitters at centimeter wavelengths. Here, we report the detection of an elongated radio source associated with the Herbig Be star or with its close infrared companion in the multiple V380 Ori system. This radio source has the characteristics of a thermal radio jet and is aligned with the direction of the giant outflow defined by HH 222 and its suggested counterpart to the SE, HH 1041. We propose that this radio jet traces the origin of the large scale HH outflow. Assuming that the jet arises from the Herbig Be star, the radio luminosity is a few times smaller than the value expected from the radio–bolometric correlation for radio jets, confirming that this is a more evolved object than those used to establish the correlation.

THE RADIO JET ASSOCIATED WITH THE MULTIPLE V380 ORI SYSTEM

International Nuclear Information System (INIS)

Rodríguez, Luis F.; Yam, J. Omar; Carrasco-González, Carlos; Anglada, Guillem; Trejo, Alfonso

2016-01-01

The giant Herbig–Haro object 222 extends over ∼6′ in the plane of the sky, with a bow shock morphology. The identification of its exciting source has remained uncertain over the years. A non-thermal radio source located at the core of the shock structure was proposed to be the exciting source. However, Very Large Array studies showed that the radio source has a clear morphology of radio galaxy and a lack of flux variations or proper motions, favoring an extragalactic origin. Recently, an optical–IR study proposed that this giant HH object is driven by the multiple stellar system V380 Ori, located about 23′ to the SE of HH 222. The exciting sources of HH systems are usually detected as weak free–free emitters at centimeter wavelengths. Here, we report the detection of an elongated radio source associated with the Herbig Be star or with its close infrared companion in the multiple V380 Ori system. This radio source has the characteristics of a thermal radio jet and is aligned with the direction of the giant outflow defined by HH 222 and its suggested counterpart to the SE, HH 1041. We propose that this radio jet traces the origin of the large scale HH outflow. Assuming that the jet arises from the Herbig Be star, the radio luminosity is a few times smaller than the value expected from the radio–bolometric correlation for radio jets, confirming that this is a more evolved object than those used to establish the correlation.

Principles behind a He-jet system and its application for isotope separation

International Nuclear Information System (INIS)

Wollnik, H.

1976-01-01

The functioning of a He-jet transport system in explained paying special attention to the use of aerosols. Three applications of such a He-jet for an isotope separation are discussed: the use behind a recoil fission product separator, the transportation of activity into the ion source of a conventional mass separator, and the transportation into an α- or β-recoil time-of-flight spectrometer. (Auth.)

Structure design and simulation research of active magnetic bearing for helium centrifugal cold compressor

Science.gov (United States)

Y Zhang, S.; Pan, W.; Wei, C. B.; Wu, J. H.

2017-12-01

Helium centrifugal cold compressors are utilized to pump gaseous helium from saturated liquid helium tank to obtain super-fluid helium in cryogenic refrigeration system, which is now being developed at TIPC, CAS. Active magnetic bearing (AMB) is replacing traditional oil-fed bearing as the optimal supporting assembly for cold compressor because of its many advantages: free of contact, high rotation speed, no lubrication and so on. In this paper, five degrees of freedom for AMB are developed for the helium centrifugal cold compressor application. The structure parameters of the axial and radial magnetic bearings as well as hardware and software of the electronic control system is discussed in detail. Based on modal analysis and critical speeds calculation, a control strategy combining PID arithmetic with other phase compensators is proposed. Simulation results demonstrate that the control method not only stables AMB system but also guarantees good performance of closed-loop behaviour. The prior research work offers important base and experience for test and application of AMB experimental platform for system centrifugal cold compressor.

Miniature rainbow schlieren deflectometry system for quantitative measurements in microjets and flames

International Nuclear Information System (INIS)

Satti, Rajani P.; Kolhe, Pankaj S.; Olcmen, Semih; Agrawal, Ajay K.

2007-01-01

Recent interest in small-scale flow devices has created the need for miniature instruments capable of measuring scalar flow properties with high spatial resolution. We present a miniature rainbow schlieren deflectometry system to nonintrusively obtain quantitative species concentration and temperature data across the whole field. The optical layout of the miniature system is similar to that of a macroscale system, although the field of view is smaller by an order of magnitude. Employing achromatic lenses and a CCD array together with a camera lens and extension tubes, we achieved spatial resolution down to 4 μm. Quantitative measurements required a careful evaluation of the optical components. The capability of the system is demonstrated by obtaining concentration measurements in a helium microjet (diameter, d=650 μm) and temperature and concentration measurements in a hydrogen jet diffusion flame from a microinjector(d=50 μm). Further, the flow field of underexpanded nitrogen jets is visualized to reveal details of the shock structures existing downstream of the jet exit

Mixed helium-3 - helium-4 calorimeter. Very low temperature calorimetry; Calorimetre mixte a helium-3 et helium-4. Calorimetrie a tres basse temperature

Energy Technology Data Exchange (ETDEWEB)

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

1966-06-01

A description is given of a double-racket calorimeter using helium-4 and helium-3 as the cryogenic fluids and making it possible to vary the temperature continuously from 0.35 K to 4.2 K. By using an electric thermal regulator together with liquid hydrogen it is possible to extend this range up to about 30 K. In the second part, a review is made of the various, methods available for measuring specific heats. The method actually used in the apparatus previously described is described in detail. The difficulties arising from the use of an exchange gas for the thermal contact have been solved by the use of adsorption pumps. (author) [French] On decrit un calorimetre a double enceinte utilisant comme fluide cryogenique l'helium-4 et l'helium-3 et permettant de varier continuement la temperature de 0,35 K a 4,2 K. L'utilisation d'un regulateur thermique electrique ainsi que celle d'hydrogene, liquide permettent d'etendre cette gamme jusqu'a 30 K environ. Dans une deuxieme partie, on passe en revue les diverses methodes de mesure des chaleurs specifiques. La methode concrete utilisee dans l'appareil precedemment decrit est exposee en detail. Les difficultes inherentes a l'utilisation de gaz d'echange comme agent de contact thermique ont ete levees par la mise en oeuvre de pompes a adsorbant. (auteur)

Operations aspects of the Fermilab Central Helium Liquefier facility

International Nuclear Information System (INIS)

Geynisman, M.G.; Makara, J.N.

1996-09-01

The Fermilab Central Helium Liquefier (CHL) facility consists of helium and nitrogen reliquefier plants operated 24 hours-a-day to supply LHe at 4.6 K and LN 2 for the Fermilab Tevatron superconducting proton-antiproton collider ring and to recover warm return gases. Operating aspects of CHL, including different equipment and systems reliability, availability, maintenance experience, safety concerns, and economics aspects are discussed

Operations aspects of the Fermilab Central Helium Liquefier Facility

International Nuclear Information System (INIS)

Geynisman, M.G.; Makara, J.N.

1995-03-01

The Fermilab Central Helium Liquefier (CHL) facility consists of helium and nitrogen reliquefier plants operated 24 hours-a-day to supply LHe at 4.6 degrees K and LN 2 for the Fermilab Tevatron superconducting proton-antiproton collider ring and to recover warm return gases. Operating aspects of CHL, including different equipment and systems reliability, availability, maintenance experience, safety concerns, and economics aspects are discussed

A new high speed, Ultrascale+ based board for the ATLAS jet calorimeter trigger system

CERN Document Server

Rocco, Elena; The ATLAS collaboration

2018-01-01

A new high speed Ultrascale+ based board for the ATLAS jet calorimeter trigger system To cope with the enhanced luminosity at the Large Hadron Collider (LHC) in 2021, the ATLAS collaboration is planning a major detector upgrade. As a part of this, the Level 1 trigger based on calorimeter data will be upgraded to exploit the fine granularity readout using a new system of Feature EXtractors (FEX), which each reconstruct different physics objects for the trigger selection. The jet FEX (jFEX) system is conceived to provide jet identification (including large area jets) and measurements of global variables within a latency budget of less then 400ns. It consists of 6 modules. A single jFEX module is an ATCA board with 4 large FPGAs of the Xilinx Ultrascale+ family, that can digest a total input data rate of ~3.6 Tb/s using up to 120 Multi Gigabit Transceiver (MGT), 24 electrical optical devices, board control and power on the mezzanines to allow flexibility in upgrading controls functions and components without aff...

Effect of a helium environment on the mechanical properties of HTGR primary system metals

International Nuclear Information System (INIS)

Chow, J.G.Y.; Soo, P.; Sabatini, R.L.

1978-01-01

Creep and high cycle fatigue tests have been carried out on Incoloy 800H and Hastelloy X in a helium environment containing 40 μ atm of H 2 O, 200 μ atm H 2 , 40 μ atm CO, 20 μ atm CH 4 and 10 μ atm CO 2 . The creep behavior of Incoloy 800H does not appear to show significant differences from that measured in air. However, the Hastelloy X at the maximum test temperature studied (871 0 C, 1600 0 F) shows behavior which is inferior. With respect to high cycle fatigue, the Incoloy 800H is weaker in the helium environment at a test temperature of 649 0 C (1200 0 F). At 760 0 C (1400 0 F) the strength in helium is higher but there is a tendency to lose strength more rapidly than for the air tests as the test time increases. Hastelloy X tested at 871 0 C (1600 0 F) also shows higher strength in helium for short test times but for extended tests the strengths in air and helium become similar. Scanning electron microprobe analyses have been carried out to correlate the strength measurements with surface oxidation characteristics and internal structural changes

D0 Silicon Upgrade: Commissioning Test Results for D-Zero's Helium Refrigerator

International Nuclear Information System (INIS)

Rucinski, Russ

1997-01-01

The test objectives are: (1) Make liquid helium and measure refrigerator capacity; (2) Measure liquid helium dewar heat leak, transfer line heat leak, and liquid nitrogen consumption rates; (3) Operate all cryogenic transfer lines; (4) Get some running time on all components; (5) Debug mechanical components, instrumentation, DMACs user interface, tune loops, and otherwise shake out any problems; (6) Get some operating time in to get familiar with system behavior; (7) Revise and/or improve operating procedures to actual practice; and (8) Identify areas for future improvement. D-Zero's stand alone helium refrigerator (STAR) liquified helium at a rate of 114 L/hr. This is consistent with other STAR installations. Refrigeration capacity was not measured due to lack of a calibrated heat load. Measured heat leaks were within design values. The helium dewar loss was measured at 2 to 4 watts or 9% per day, the solenoid and VLPC helium transfer lines had a heat leak of about 20 watts each. The liquid nitrogen consumption rates of the mobile purifier, STAR, and LN2 subcooler were measured at 20 gph, 20 to 64 gph, and 3 gph respectively. All cryogenic transfer lines including the solenoid and visible light photon counter (VLPC) transfer lines were cooled to their cryogenic operating temperatures. This included independent cooling of nitrogen shields and liquid helium components. No major problems were observed. The system ran quite well. Many problems were identified and corrected as they came up. Areas for improvement were noted and will be implemented in the future. The instrumentation and control system operated commendably during the test. The commissioning test run was a worthwhile and successful venture.

Determination of helium in beryl minerals

International Nuclear Information System (INIS)

Souza Barcellos, E. de.

1985-08-01

In order to obtain the diffusion coefficients of helium in beryl and phenacite samples at various temperatures, helium leak rates were measured in these minerals at these temperatures. Mass spectrometry (MS) was used to obtain helium leak rates and the gas flow was plotted against time. The gas quantity determined by MS was first obtained at various temperatures until no helium leak rate was detected. After that, these samples were irradiated with fast neutrons to produce helium which was measured again. This procedure was used to estimate the experimental error. The quantity of helium produced by interaction of gamma radiation with beryl minerals was theoretically calculated from the amount of thorium-232 at the neighbourhood of the samples. The quantity of helium produced in the minerals due to uranium and thorium decay was calculated using the amount of these heavy elements, and the results were compared with the amounts determined by MS. The amount of potassium-40 was determined in order to derive the quantity of argonium-40, since some workers found argonium in excess in these minerals. The quantity of helium in the beryl samples (s) was determined in the center and in the surface of the samples in order to obtain informations about the effectiveness of the Be(α, η) He reaction. Beryl and phenacite minerals were choosen in this research since they are opposite each other with respect to the helium contents. Both have beryllium in their compositon but beryl hold a large amount of helium while phenacite, in spite of having about three times more beryllium than beryl, do not hold the gas. (author) [pt

Helium localisation in tritides

International Nuclear Information System (INIS)

Flament, J.L.; Lozes, G.

1982-06-01

Study of titanium and LaNi 5 type alloys tritides lattice parameters evolution revealed that helium created by tritium decay remains in interstitial sites up to a limit material dependant concentration. Beyond this one exceeding helium precipites in voids [fr

Molecular beams with extremely narrow velocity spreads from free jet expansions

International Nuclear Information System (INIS)

Buck, U.; Dueker, M.; Pauly, H.; Pust, D.

1974-01-01

Velocity distributions in molecular beams from free jets of light gases (He, H 2 and mixtures of 1% Xe in H 2 ) were studied as a function of the source Knudsen number. They were found to be narrower than what would be expected from previous studies. Mach numbers of 50 were observed for helium at a source temperature of T=85 deg K. The speed ratio for sources at room temperature was found to be S=29 for pure H 2 and 35 for a 1% Xe-99% H 2 mixture

Very forward jet, Mueller Navelet jets and jet gap jet measurements in CMS

CERN Document Server

Cerci, Salim

2018-01-01

The measurements of very forward jet, Mueller-Navelet jets and jet-gap-jet events are presented for different collision energies. The analyses are based on data collected with the CMS detector at the LHC. Jets are defined through the anti-$k_\\mathrm{t}$ clustering algorithm for different cone sizes. Jet production studies provide stringent tests of quantum chromodynamics (QCD) and contribute to tune Monte Carlo (MC) simulations and phenomenological models. The measurements are compared to predictions from various Monte Carlo event generators.

r-process nucleosynthesis in dynamic helium-burning environments

Science.gov (United States)

Cowan, J. J.; Cameron, A. G. W.; Truran, J. W.

1985-01-01

The results of an extended examination of r-process nucleosynthesis in helium-burning enviroments are presented. Using newly calculated nuclear rates, dynamical r-process calculations have been made of thermal runaways in helium cores typical of low-mass stars and in the helium zones of stars undergoing supernova explosions. These calculations show that, for a sufficient flux of neutrons produced by the C-13 neutron source, r-process nuclei in solar proportions can be produced. The conditions required for r-process production are found to be 10 to the 20th-10 to the 21st neutrons per cubic centimeter for times of 0.01-0.1 s and neutron number densities in excess of 10 to the 19th per cubic centimeter for times of about 1 s. The amount of C-13 required is found to be exceedingly high - larger than is found to occur in any current stellar evolutionary model. It is thus unlikely that these helium-burning environments are responsible for producing the bulk of the r-process elements seen in the solar system.

Studying the non-thermal plasma jet characteristics and application on bacterial decontamination

Science.gov (United States)

Al-rawaf, Ali F.; Fuliful, Fadhil Khaddam; Khalaf, Mohammed K.; Oudah, Husham. K.

2018-04-01

Non-thermal atmospheric-pressure plasma jet represents an excellent approach for the decontamination of bacteria. In this paper, we want to improve and characterize a non-thermal plasma jet to employ it in processes of sterilization. The electrical characteristics was studied to describe the discharge of the plasma jet and the development of plasma plume has been characterized as a function of helium flow rate. Optical emission spectroscopy was employed to detect the active species inside the plasma plume. The inactivation efficiency of non-thermal plasma jet was evaluated against Staphylococcus aureus bacteria by measuring the diameter of inhibition zone and the number of surviving cells. The results presented that the plasma plume temperature was lower than 34° C at a flow rate of 4 slm, which will not cause damage to living tissues. The diameter of inhibition zone is directly extended with increased exposure time. We confirmed that the inactivation mechanism was unaffected by UV irradiation. In addition, we concluded that the major reasons for the inactivation process of bacteria is because of the action of the reactive oxygen and nitrogen species which formed from ambient air, while the charged particles played a minor role in the inactivation process.

Orion Exploration Flight Test Reaction Control System Jet Interaction Heating Environment from Flight Data

Science.gov (United States)

White, Molly E.; Hyatt, Andrew J.

2016-01-01

The Orion Multi-Purpose Crew Vehicle (MPCV) Reaction Control System (RCS) is critical to guide the vehicle along the desired trajectory during re-­-entry. However, this system has a significant impact on the convective heating environment to the spacecraft. Heating augmentation from the jet interaction (JI) drives thermal protection system (TPS) material selection and thickness requirements for the spacecraft. This paper describes the heating environment from the RCS on the afterbody of the Orion MPCV during Orion's first flight test, Exploration Flight Test 1 (EFT-1). These jet plumes interact with the wake of the crew capsule and cause an increase in the convective heating environment. Not only is there widespread influence from the jet banks, there may also be very localized effects. The firing history during EFT-1 will be summarized to assess which jet bank interaction was measured during flight. Heating augmentation factors derived from the reconstructed flight data will be presented. Furthermore, flight instrumentation across the afterbody provides the highest spatial resolution of the region of influence of the individual jet banks of any spacecraft yet flown. This distribution of heating augmentation across the afterbody will be derived from the flight data. Additionally, trends with possible correlating parameters will be investigated to assist future designs and ground testing programs. Finally, the challenges of measuring JI, applying this data to future flights and lessons learned will be discussed.

Thermal-hydraulic optimization of flexible transfer lines for liquid helium; Thermohydraulische Optimierung flexibler Transferleitungen fuer Fluessighelium

Energy Technology Data Exchange (ETDEWEB)

Dittmar, Nico; Haberstroh, Christoph; Hesse, U. [Technische Univ. Dresden (Germany). Bitzer-Stiftungsprofessur fuer Kaelte-, Kryo- und Kompressorentechnik; Wolfram, M.; Krzyzowski, M.; Raccanelli, A. [CryoVac Gesellschaft fuer Tieftemperaturtechnik mbH und Co. KG, Troisdorf (Germany)

2014-07-01

Cooling systems and applications at very low temperatures are based on the use of liquid helium as cryogenic agent; the normal boiling temperature of helium-4 is 4.2 K. Due to the restricted economic production possibilities and the high energetic expenditure for helium liquefaction an efficient and sustainable handling with the resources is recommended. In university facilities the liquid helium is usually stored in containers and filled into smaller containers for transport using cryogenic transfer lines. This procedure can cause 20% loss by evaporation due to heat input and friction pressure losses. The gaseous helium has to be collected for re-liquefaction. The contribution shows that using systematic measurements an increase of the transfer rate and the efficiency of the helium filling system can be reached by a modified transfer line design.

Leak detection on the DIII-D tokamak using helium entrainment techniques

International Nuclear Information System (INIS)

Brooks, N.H.; Baxi, C.; Anderson, P.

1988-01-01

The entrainment of helium in a viscous gas flow was utilized to compartmentalize, and then to pinpoint, a leak across the inner skin of the double-walled DIII-D vacuum vessel. Inaccessible from the outside, the leak connected the cooling channels in the wall interspace with the primary vacuum chamber. By entraining helium in the pressurized flow from the single-pass gas circulation system, well-defined portions of the wall were exposed to helium without disassembly of the poorly accessible cooling manifolds. Varying the helium injection point permitted the localization of the leak to a single 30 0 toroidal sector of the vessel. The exact location of the leak was found from inside the vessel by spraying helium on suspect regions, while sweeping the contents of the cooling channels to the foreline of a Varian Contraflow leak detector with a 0.1 Pa m 3 /s flow of nitrogen. Flow speed calculations were used to predict the response time to entrained helium of the actual leak detection setup

A New Generation of Real-Time Systems in the JET Tokamak

Science.gov (United States)

Alves, Diogo; Neto, Andre C.; Valcarcel, Daniel F.; Felton, Robert; Lopez, Juan M.; Barbalace, Antonio; Boncagni, Luca; Card, Peter; De Tommasi, Gianmaria; Goodyear, Alex; Jachmich, Stefan; Lomas, Peter J.; Maviglia, Francesco; McCullen, Paul; Murari, Andrea; Rainford, Mark; Reux, Cedric; Rimini, Fernanda; Sartori, Filippo; Stephen, Adam V.; Vega, Jesus; Vitelli, Riccardo; Zabeo, Luca; Zastrow, Klaus-Dieter

2014-04-01

Recently, a new recipe for developing and deploying real-time systems has become increasingly adopted in the JET tokamak. Powered by the advent of x86 multi-core technology and the reliability of JET's well established Real-Time Data Network (RTDN) to handle all real-time I/O, an official Linux vanilla kernel has been demonstrated to be able to provide real-time performance to user-space applications that are required to meet stringent timing constraints. In particular, a careful rearrangement of the Interrupt ReQuests' (IRQs) affinities together with the kernel's CPU isolation mechanism allows one to obtain either soft or hard real-time behavior depending on the synchronization mechanism adopted. Finally, the Multithreaded Application Real-Time executor (MARTe) framework is used for building applications particularly optimised for exploring multi-core architectures. In the past year, four new systems based on this philosophy have been installed and are now part of JET's routine operation. The focus of the present work is on the configuration aspects that enable these new systems' real-time capability. Details are given about the common real-time configuration of these systems, followed by a brief description of each system together with results regarding their real-time performance. A cycle time jitter analysis of a user-space MARTe based application synchronizing over a network is also presented. The goal is to compare its deterministic performance while running on a vanilla and on a Messaging Real time Grid (MRG) Linux kernel.

Helium leak testing of large pressure vessels or subassemblies

International Nuclear Information System (INIS)

Hopkins, J.S.; Valania, J.J.

1977-01-01

Specifications for pressure-vessel components [such as the intermediate heat exchangers (IHX)] for service in the liquid metal fast breeder reactor facilities require helium leak testing of pressure boundaries to very exacting standards. The experience of Foster Wheeler Energy Corporation (FWEC) in successfully leak-testing the IHX shells and bundle assemblies now installed in the Fast Flux Test Facility at Richland, WA is described. Vessels of a somewhat smaller size for the closed loop heat exchanger system in the Fast Flux Test Facility have also been fabricated and helium leak tested for integrity of the pressure boundary by FWEC. Specifications on future components call for helium leak testing of the tube to tubesheet welds of the intermediate heat exchangers

Measurement of electric field distribution along the plasma column in Microwave jet discharges at atmospheric pressure

International Nuclear Information System (INIS)

Razzak, M. Abdur; Takamura, Shuichi; Tsujikawa, Takayuki; Shibata, Hideto; Hatakeyama, Yuto

2009-01-01

A new technique for the direct measurement of electric field distribution along the plasma column in microwave jet discharges is developed and employed. The technique is based on a servomotor-controlled reciprocating antenna moving along the nozzle axis and plasma column. The measurement technique is applied to a rectangular waveguide-based 2.45 GHz argon and helium plasma jets generated by using the modified TIAGO nozzle at atmospheric pressure with a microwave power of less than 500 W. The measurement has been done with and without igniting the plasma jet in order to investigate the standing wave propagation along the nozzle axis and plasma column. It is observed that the electric field decay occurs slowly in space with plasma ignition than that of without plasma, which indicates the surface electromagnetic wave propagation along the plasma column in order to sustain the plasma jet. This study enables one to design, determine and optimize the size and structure of launcher nozzle, which plays an important role for the stable and efficient microwave plasma generators. (author)

Resistivity studies of interstitial helium mobility in niobium

International Nuclear Information System (INIS)

Chen, C.G.; Birnbaum, H.K.; Johnson, A.B. Jr.

1979-01-01

The mobility of interstitial helium in Nb and Nb-O alloys was studied in the temperature range of 10-383 K using resistivity measurements. The helium was introduced by radioactive decay of solute tritium (approximately 1 at%). At T < 100 K the resistivity increased due to conversion of tritium trapped at oxygen interstititals to helium. The formation of helium caused a very significant resistance increase at room temperature and above. The results suggest that helium is mobile at temperatures above 295 K and that the precipitation of large helium bubbles occurs along grain boundaries. The mobile helium species may either be single interstitials or small helium clusters. The activation enthalpy for the diffusion of the mobile helium species was estimated to be about 55 kJ/mol (0.66 eV). (Auth.)

Helium-induced hardening effect in polycrystalline tungsten

Science.gov (United States)

Kong, Fanhang; Qu, Miao; Yan, Sha; Zhang, Ailin; Peng, Shixiang; Xue, Jianming; Wang, Yugang

2017-09-01

In this paper, helium induced hardening effect of tungsten was investigated. 50 keV He2+ ions at fluences vary from 5 × 1015 cm-2 to 5 × 1017 cm-2 were implanted into polycrystalline tungsten at RT to create helium bubble-rich layers near the surface. The microstructure and mechanical properties of the irradiated specimens were studied by TEM and nano-indentor. Helium bubble rich layers are formed in near surface region, and the layers become thicker with the rise of fluences. Helium bubbles in the area of helium concentration peak are found to grow up, while the bubble density is almost unchanged. Obvious hardening effect is induced by helium implantation in tungsten. Micro hardness increases rapidly with the fluence firstly, and more slowly when the fluence is above 5 × 1016 cm-2. The hardening effect of tungsten can be attributed to helium bubbles, which is found to be in agreement with the Bacon-Orowan stress formula. The growing diameter is the major factor rather than helium bubbles density (voids distance) in the process of helium implantation at fluences below 5 × 1017 cm-2.

Low helium flux from the mantle inferred from simulations of oceanic helium isotope data

Science.gov (United States)

Bianchi, Daniele; Sarmiento, Jorge L.; Gnanadesikan, Anand; Key, Robert M.; Schlosser, Peter; Newton, Robert

2010-09-01

The high 3He/ 4He isotopic ratio of oceanic helium relative to the atmosphere has long been recognized as the signature of mantle 3He outgassing from the Earth's interior. The outgassing flux of helium is frequently used to normalize estimates of chemical fluxes of elements from the solid Earth, and provides a strong constraint to models of mantle degassing. Here we use a suite of ocean general circulation models and helium isotope data obtained by the World Ocean Circulation Experiment to constrain the flux of helium from the mantle to the oceans. Our results suggest that the currently accepted flux is overestimated by a factor of 2. We show that a flux of 527 ± 102 mol year - 1 is required for ocean general circulation models that produce distributions of ocean ventilation tracers such as radiocarbon and chlorofluorocarbons that match observations. This new estimate calls for a reevaluation of the degassing fluxes of elements that are currently tied to the helium fluxes, including noble gases and carbon dioxide.

The effect of ethanol gas impurity on the discharge mode and discharge products of argon plasma jet at atmospheric pressure

Science.gov (United States)

Xia, Wenjie; Liu, Dingxin; Xu, Han; Wang, Xiaohua; Liu, Zhijie; Rong, Mingzhe; Kong, Michael G.

2018-05-01

Argon is a widely used working gas of plasmas, which is much cheaper than helium but on the other hand much more difficult to generate diffuse discharge at atmospheric pressure. In order to meet the application requirements, plenty of researches have been reported to facilitate the diffuse discharge happening for argon plasmas, and in this paper an approach of using ethanol gas (EtOH) impurity is investigated. The discharge characteristics of Ar + EtOH plasma jet are studied as a function of the applied voltage and the concentration of EtOH, from which the concentration of EtOH between ∼200 and ∼3300 parts per million (ppm) is determined necessary for the generation of diffuse discharge. Compared with the helium plasma jet in literature, it is deduced that the diffuse discharge is probably caused by the Penning ionization happening between the metastable argon and EtOH. The discharge products of Ar + EtOH (672 ppm) plasma jet are measured and the corresponding chemistry pathways are analyzed. About 20% of EtOH is decomposed via complex chemical reactions to form more than a dozen of neutral species, such as CH3CHO, CH3COOH, CO, H2O, and C n H2n+2 (n ≥ 3), and various kinds of ionic species, including C+, CH+, ArH+, {{{{O}}}2}-, CH3CH2O‑, etc.

Determination of migration of ion-implanted helium in silica by proton backscattering spectrometry

Energy Technology Data Exchange (ETDEWEB)

Szakacs, G. [KFKI Research Institute for Particle and Nuclear Physics, P.O. Box 49, H-1525 Budapest (Hungary); Szilagyi, E. [KFKI Research Institute for Particle and Nuclear Physics, P.O. Box 49, H-1525 Budapest (Hungary)], E-mail: szilagyi@rmki.kfki.hu; Paszti, F.; Kotai, E. [KFKI Research Institute for Particle and Nuclear Physics, P.O. Box 49, H-1525 Budapest (Hungary)

2008-04-15

Understanding the processes caused by ion implantation of light ions in dielectric materials such as silica is important for developing the diagnostic systems used in fusion and fission environments. Recently, it has been shown that ion-implanted helium is able to escape from SiO{sub 2} films. To study this process in details, helium was implanted into the central part of a buried SiO{sub 2} island up to a fluence of 4 x 10{sup 17} He/cm{sup 2}. The implanted helium could be detected in the SiO{sub 2} island, if the oxide was insulated properly from the vacuum. The shape of the helium depth distributions was far from SRIM simulation because helium distributed in the whole 1 {mu}m thick oxide layer. After the ion implantation, helium was observed only on the implanted spot. After nine months the implanted helium filled out the whole oxide island as it was expected from the high diffusivity.

Determination of migration of ion-implanted helium in silica by proton backscattering spectrometry

International Nuclear Information System (INIS)

Szakacs, G.; Szilagyi, E.; Paszti, F.; Kotai, E.

2008-01-01

Understanding the processes caused by ion implantation of light ions in dielectric materials such as silica is important for developing the diagnostic systems used in fusion and fission environments. Recently, it has been shown that ion-implanted helium is able to escape from SiO 2 films. To study this process in details, helium was implanted into the central part of a buried SiO 2 island up to a fluence of 4 x 10 17 He/cm 2 . The implanted helium could be detected in the SiO 2 island, if the oxide was insulated properly from the vacuum. The shape of the helium depth distributions was far from SRIM simulation because helium distributed in the whole 1 μm thick oxide layer. After the ion implantation, helium was observed only on the implanted spot. After nine months the implanted helium filled out the whole oxide island as it was expected from the high diffusivity

Observation of visible emission from the molecular helium ion in the afterglow of a dense helium Z-pinch plasma

International Nuclear Information System (INIS)

Tucker, J.E.; Brake, M.L.; Gilgenbach, R.M.

1986-01-01

The authors present the results of axial and radial time resolved visible emission spectroscopy from the afterglow of a dense helium Z-pinch. These results show that the visible emissions in the pinch afterglow are dominated by line emissions from molecular helium and He II. Axial spectroscopy measurements show the occurrence of several absorption bands which cannot be identified as molecular or atomic helium nor impurities from the discharge chamber materials. The authors believe that these absorption bands are attributable to the molecular helium ion which is present in the discharge. The molecular ion has been observed by others in low pressure and temperature helium discharges directly by means of mass spectrometry and indirectly by the presence of helium atoms in the 2/sup 3/S state, (the He 2/sup 3/S state is believed to result from molecular helium ion recombination). However, the molecular helium ion has not previously been observed spectroscopically

Development Status of the Helium Circulator for the HCS of HCCR-TBS

International Nuclear Information System (INIS)

Lee, Eo Hwak; Jin, Hyung Gon; Yoon, Jae Sung; Kim, Suk Kwon; Lee, Dong Won; Lee, Si Woo; Cho, Seung Yon

2016-01-01

The calculated eddy current loss on the stainless steel sealing cap of the magnetic coupling device is very high. To solve the eddy current loss problem of the sealing cap, a glass fiber composite, non-conductive and high strength material, is adapted as a material of the sealing cap. The HCCR TBM will be cooled down by HCS (Helium Cooling System), supply high pressure (8 MPa) and temperature (300 .deg. C) helium coolant with 1.15 kg/s of mass flow for nominal operation. The real-scale helium circulator, which is main component of the HCS, has been developed since 2014. In present study, design and manufacture progress of the helium circulator and its verification test plan are described. The real-scale circulator has been developed to provide high temperature and pressure of helium flow as a coolant of the HCCR TBM. To prevent helium leakage, magnetic coupling design was adapted between the shaft and the impeller

Deformations of free jets

Science.gov (United States)

Paruchuri, Srinivas

This thesis studies three different problems. First we demonstrate that a flowing liquid jet can be controllably split into two separate subfilaments through the applications of a sufficiently strong tangential stress to the surface of the jet. In contrast, normal stresses can never split a liquid jet. We apply these results to observations of uncontrolled splitting of jets in electric fields. The experimental realization of controllable jet splitting would provide an entirely novel route for producing small polymeric fibers. In the second chapter we present an analytical model for the bending of liquid jets and sheets from temperature gradients, as recently observed by Chwalek et al. [Phys. Fluids, 14, L37 (2002)]. The bending arises from a local couple caused by Marangoni forces. The dependence of the bending angle on experimental parameters is presented, in qualitative agreement with reported experiments. The methodology gives a simple framework for understanding the mechanisms for jet and sheet bending. In chapter 4 we address the discrepancy between hydrodynamic theory of liquid jets, and the snap-off of narrow liquid jets observed in molecular dynamics (MD) simulations [23]. This has been previously attributed to the significant role of thermal fluctuations in nanofluidic systems. We argue that hydrodynamic description of such systems should include corrections to the Laplace pressure which result from the failure of the sharp interface assumption when the jet diameter becomes small enough. We show that this effect can in principle give rise to jet shapes similar to those observed in MD simulations, even when thermal fluctuations are completely neglected. Finally we summarize an algorithm developed to simulate droplet impact on a smooth surface.

Production of radiatively cooled hypersonic plasma jets and links to astrophysical jets

International Nuclear Information System (INIS)

Lebedev, S V; Ciardi, A; Ampleford, D J; Bland, S N; Bott, S C; Chittenden, J P; Hall, G N; Rapley, J; Jennings, C; Sherlock, M; Frank, A; Blackman, E G

2005-01-01

We present results of high energy density laboratory experiments on the production of supersonic radiatively cooled plasma jets with dimensionless parameters (Mach number ∼30, cooling parameter ∼1 and density contrast ρ j /ρ a ∼ 10) similar to those in young stellar objects jets. The jets are produced using two modifications of wire array Z-pinch driven by 1 MA, 250 ns current pulse of MAGPIE facility at Imperial College, London. In the first set of experiments the produced jets are purely hydrodynamic and are used to study deflection of the jets by the plasma cross-wind, including the structure of internal oblique shocks in the jets. In the second configuration the jets are driven by the pressure of the toroidal magnetic field and this configuration is relevant to the astrophysical models of jet launching mechanisms. Modifications of the experimental configuration allowing the addition of the poloidal magnetic field and angular momentum to the jets are also discussed. We also present three-dimensional resistive magneto-hydrodynamic simulations of the experiments and discuss the scaling of the experiments to the astrophysical systems

Helium Extraction from LNG End Flash

OpenAIRE

Kim, Donghoi

2014-01-01

Helium is an invaluable element as it is widely used in industry such as cryo-genics and welding due to its unique properties. However, helium shortage is expected in near future because of increasing demand and the anxiety of sup-ply. Consequently, helium production has attracted the attention of industry. The main source of He is natural gas and extracting it from LNG end-flash is considered as the most promising way of producing crude helium. Thus, many process suppliers have proposed proc...

Modular helium reactor for non-electric applications

International Nuclear Information System (INIS)

Shenoy, A.

1997-01-01

The high temperature gas-cooled Modular Helium Reactor (MHR) is an advanced, high efficiency reactor system which can play a vital role in meeting the future energy needs of the world by contributing not only to the generation of electric power, but also the non-electric energy traditionally served by fossil fuels. This paper summarizes work done over 20 years, by several people at General Atomics, how the Modular Helium Reactor can be integrated to provide different non-electric applications during Process Steam/Cogeneration for industrial application, Process Heat for transportation fuel development and Hydrogen Production for various energy applications. The MHR integrates favorably into present petrochemical and primary metal process industries, heavy oil recovery, and future shale oil recovery and synfuel processes. The technical fit of the Process Steam/Cogeneration Modular Helium Reactor (PS/C-MHR) into these processes is excellent, since it can supply the required quantity and high quality of steam without fossil superheating. 12 refs, 25 figs, 2 tabs

Feasibility of lunar Helium-3 mining

Science.gov (United States)

Kleinschneider, Andreas; Van Overstraeten, Dmitry; Van der Reijnst, Roy; Van Hoorn, Niels; Lamers, Marvin; Hubert, Laurent; Dijk, Bert; Blangé, Joey; Hogeveen, Joel; De Boer, Lennaert; Noomen, Ron

With fossil fuels running out and global energy demand increasing, the need for alternative energy sources is apparent. Nuclear fusion using Helium-3 may be a solution. Helium-3 is a rare isotope on Earth, but it is abundant on the Moon. Throughout the space community lunar Helium-3 is often cited as a major reason to return to the Moon. Despite the potential of lunar Helium-3 mining, little research has been conducted on a full end-to-end mission. This abstract presents the results of a feasibility study conducted by students from Delft University of Technology. The goal of the study was to assess whether a continuous end-to-end mission to mine Helium-3 on the Moon and return it to Earth is a viable option for the future energy market. The set requirements for the representative end-to-end mission were to provide 10% of the global energy demand in the year 2040. The mission elements have been selected with multiple trade-offs among both conservative and novel concepts. A mission architecture with multiple decoupled elements for each transportation segment (LEO, transfer, lunar surface) was found to be the best option. It was found that the most critical element is the lunar mining operation itself. To supply 10% of the global energy demand in 2040, 200 tons of Helium-3 would be required per year. The resulting regolith mining rate would be 630 tons per second, based on an optimistic concentration of 20 ppb Helium-3 in lunar regolith. Between 1,700 to 2,000 Helium-3 mining vehicles would be required, if using University of Wisconsin’s Mark III miner. The required heating power, if mining both day and night, would add up to 39 GW. The resulting power system mass for the lunar operations would be in the order of 60,000 to 200,000 tons. A fleet of three lunar ascent/descent vehicles and 22 continuous-thrust vehicles for orbit transfer would be required. The costs of the mission elements have been spread out over expected lifetimes. The resulting profits from Helium

Track Reconstruction and b-Jet Identification for the ATLAS Trigger System

CERN Document Server

Coccaro, A; The ATLAS collaboration

2011-01-01

A sophisticated trigger system, capable of real-time track reconstruction, is in place in the ATLAS experiment, to reject most of the events containing uninteresting background collisions while preserving as much as possible the interesting physics signals. The strategy adopted for fast reconstruction of charged tracks and in particular its application to the selection of jets from the hadronization of b-quarks is reviewed. Track reconstruction is routinely used for selection based on various physics objects while b-jet triggers are actively selecting events from the beginning of the 2011 LHC data-taking campaign.

Use of separating nozzles or ultra-centrifuges for obtaining helium from gas mixtures containing helium

International Nuclear Information System (INIS)

Reimann, T.

1987-01-01

To obtain helium from gas mixtures containing helium, particularly from natural gas, it is proposed to match the dimensions of the separation devices for a ratio of the molecular weights to be separated of 4:1 of more, which ensures a higher separation factor and therefore a smaller number of separation stages to be connected in series. The process should make reasonably priced separation of helium possible. (orig./HP) [de

Helium diffusion in nickel at high temperatures

International Nuclear Information System (INIS)

Philipps, V.

1980-09-01

Helium has been implanted at certain temperatures between 800 and 1250 0 C into single and polycrystalline Ni-samples with implantation depths between 15 and 90 μm. Simultaneously the helium reemission from the sample is measured by a mass-spectrometer. It has been shown that the time dependence of the observed reemission rate is governed by volume diffusion of the helium. Measuring this time dependence as a function of temperature the helium diffusion constant has been determined. The He-diffusion is interpreted as a interstitial diffusion hindered by thermal vacancies. Depending on the implantation depth more or less of the implanted helium remains in the sample and forms large helium bubbles. (orig./GSCH)

Neutron-induced helium implantation in GCFR cladding

International Nuclear Information System (INIS)

Yamada, H.; Poeppel, R.B.; Sevy, R.H.

1980-10-01

The neutron-induced implantation of helium atoms on the exterior surfaces of the cladding of a prototypic gas-cooled fast reactor (GCFR) has been investigated analytically. A flux of recoil helium particles as high as 4.2 x 10 10 He/cm 2 .s at the cladding surface has been calculated at the peak power location in the core of a 300-MWe GCFR. The calculated profile of the helium implantation rates indicates that although some helium is implanted as deep as 20 μm, more than 99% of helium particles are implanted in the first 2-μm-deep layer below the cladding surface. Therefore, the implanted helium particles should mainly affect surface properties of the GCFR cladding

Simulation of liquid helium

International Nuclear Information System (INIS)

Ceperley, D.M.

1985-07-01

The author discusses simulation methods for quantum mechanical systems at finite temperatures. Recently it has been shown that static properties of some quantum systems can be obtained by simulation in a straightforward manner using path integrals, albeit with an order of magnitude more computing effort needed than for the corresponding classical systems. Some dynamical information can be gleaned from these simulations as will be discussed below. But this is very limited - there is no quantum version of the molecular dynamics method. The path integral method is illustrated by discussing the application to liquid helium. 12 refs., 8 figs

Cyclotron resonance for electrons over helium in resonator

CERN Document Server

Shikin, V B

2002-01-01

The problem on the cyclotron resonance (CR) for electrons on the helium film, positioned in the resonator lower part, is solved. It is shown, that it relates to one of the examples of the known problem on the oscillations of the coupled oscillators system. The coupling constant between these oscillators constituting the variable function of the problem parameters. It is minimal in the zero magnetic field and reaches its maximum under the resonance conditions, when the cyclotron frequency coincides with one of the resonator modes. The CR details of the Uhf CR-energy absorption coupled by the electrons + resonator system, are calculated. The applications of the obtained results to the available CR experiments for electrons over helium

Diffuse Helium Emission as a Precursory Sign of Volcanic Unrest

Science.gov (United States)

Padron, E.; Perez, N.; Hernandez Perez, P. A.; Sumino, H.; Melian Rodriguez, G.; Barrancos, J.; Nolasco, D.; Padilla, G.; Dionis, S.; Rodriguez, F.; Hernandez, I.; Calvo, D.; Peraza, M.; Nagao, K.

2012-12-01

Since July 16, 2011, an anomalous seismicity at El Hierro island, the youngest and smallest of the Canary Islands, was recorded by IGN seismic network. After the occurrence of more than 10,000 seismic events, volcanic tremor was recorded since 05:15 of the October 10, by all of the seismic stations on the island, with highest amplitudes recorded in the southernmost station. During the afternoon of October 12 a large light-green coloured area was observed in the sea to the souht of La Restinga village (at the southernmost part of El Hierro island), suggesting the existence of a submarine eruption. Since October 12, frequent episodes of, turbulent gas emission and foaming, and the appearance of steamy lava fragments has been observed on the sea surface. As part of the volcanic surveillance of the island, the Instituto Volcanologico de Canarias (INVOLCAN) geochemical monitoring program is carrying out diffuse helium surveys on the surface environment of El Hierro (soil atmosphere). This nobel gas has been investigated because it has been considered an almost ideal geochemical indicator because it is chemically inert, physically stable, nonbiogenic, sparingly soluble in water under ambient conditions and almost non-adsorbable. At each survey, 600 sampling sites covering the whole island and following an homogeneous distribution are selected for helium measurements in the soil gases, The helium concentration gradients with respect to its value on air (5.24 ppm) allow us to estimate a pure diffusive emission rate of helium throughout the island. The first survey was carried out on the summer of 2003, when the island was on a quiescence period. At this survey, the amount of helium released by the volcanic system of El Hierro was estimated in 6 kg/d. Since the beginning of the seismic unrest, 13 helium emission surveys have been carried out. The helium emission rate has shown an excellent agreement with the evolution of the volcanic crisis of the island, reaching 30 kg

Effects of weak localization in quasi-one-dimensional electronic system over liquid helium

CERN Document Server

Kovdrya, Y Z; Gladchenko, S P

2001-01-01

One measured rho sub x sub x magnetoresistance of a quasi-one-dimensional electronic system over liquid helium within gas scattering range (1.3-2.0 K temperature range). It is shown that with increase of magnetic field the magnetoresistance is reduced at first and them upon passing over minimum it begins to increase from rho sub x sub x approx B sup 2 law. One anticipated that the negative magnetoresistance detected in the course of experiments resulted from the effects of weak localization. The experiment results are in qualitative conformity with the theoretical model describing processes of weak localization in single-dimensional nondegenerate electronic systems

Single-jet gas cooling of in-beam foils or specimens: Prediction of the convective heat-transfer coefficient

Science.gov (United States)

Steyn, Gideon; Vermeulen, Christiaan

2018-05-01

An experiment was designed to study the effect of the jet direction on convective heat-transfer coefficients in single-jet gas cooling of a small heated surface, such as typically induced by an accelerated ion beam on a thin foil or specimen. The hot spot was provided using a small electrically heated plate. Heat-transfer calculations were performed using simple empirical methods based on dimensional analysis as well as by means of an advanced computational fluid dynamics (CFD) code. The results provide an explanation for the observed turbulent cooling of a double-foil, Havar beam window with fast-flowing helium, located on a target station for radionuclide production with a 66 MeV proton beam at a cyclotron facility.

Quantum statistics and liquid helium 3 - helum 4 mixtures

International Nuclear Information System (INIS)

Cohen, E.G.D.

1979-01-01

The behaviour of liquid helium 3-helium 4 mixtures is considered from the point of view of manifestation of quantum statistics effects in macrophysics. The Boze=Einstein statistics is shown to be of great importance for understanding superfluid helium-4 properties whereas the Fermi-Dirac statistics is of importance for understanding helium-3 properties. Without taking into consideration the interaction between the helium atoms it is impossible to understand the basic properties of liquid helium 33 - helium 4 mixtures at constant pressure. Proposed is a simple model of the liquid helium 3-helium 4 mixture, namely the binary mixture consisting of solid spheres of two types subjecting to the Fermi-Dirac and Bose-Einstein statistics relatively. This model predicts correctly the most surprising peculiarities of phase diagrams of concentration dependence on temperature for helium solutions. In particular, the helium 4 Bose-Einstein statistics is responsible for the phase lamination of helium solutions at low temperatures. It starts in the peculiar critical point. The helium 4 Fermi-Dirac statistics results in incomplete phase lamination close to the absolute zero temperatures, that permits operation of a powerful cooling facility, namely refrigerating machine on helium solution

A new diagnostic for the tritium phase of JET covering the visible and UV wavelength range

International Nuclear Information System (INIS)

Morsi, H.W.; Hatzky, R.; Hellermann, M. von

1991-01-01

The objectives of an active-phase direct optical link between the JET tokamak and spectral instruments beyond the biological shield are manifold. The present optical fibre links, which are used as a standard at JET, may be subjected to much enhanced radiation levels in future operations with D-T plasmas, and a direct optical link, based on a system of remotely controllable relay mirrors, will be a vital test for future activated fusion devices. A further aim is to extend the spectral range of exploitable charge exchange (CX) lines to shorter wavelengths, which is presently limited by the transmission of quartz fibres to CX lines above 4000 A. The latter aspect is particularly relevant in the case of HeII where the sole CX line of HeII (n = 4 to 3) in the visible, is superimposed by a BeIV CX line (n = 8 to 6) at the same wavelength (4685 A). This fact constraints the present helium analysis to plasma conditions with n(Be)<0.3·n(He). For future alpha particle studies, especially at low alpha particle densities, this constraint may require either sophisticated analysis procedures or alternatively the use of other less ''disturbed'' lines, possibly in the UV wavelength range. Finally the UV link is intended to provide an optical transfer channel for short optical jumpers to other JET observation ports - for example coherent fibre bundles imaging the X-point strike zone - to the diagnostic instruments in the roof laboratory of JET. (author) 1 ref., 6 figs

High Efficiency Regenerative Helium Compressor, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Helium plays several critical rolls in spacecraft propulsion. High pressure helium is commonly used to pressurize propellant fuel tanks. Helium cryocoolers can be...

Shock and vibration protection of submerged jet impingement cooling systems: Theory and experiment

International Nuclear Information System (INIS)

Haji Hosseinloo, Ashkan; Tan, Siow Pin; Yap, Fook Fah; Toh, Kok Chuan

2014-01-01

In the recent years, advances in high power density electronics and computing systems have pushed towards more advanced thermal management technologies and higher-capacity cooling systems. Among different types of cooling systems, jet impingement technology has gained attention and been widely used in different industries for its adaptability, cooling uniformity, large heat capacity, and ease of its localization. However, these cooling systems may not function properly in dynamically harsh environment inherent in many applications such as land, sea and air transportation. In this research article, a novel double-chamber jet impingement cooling system is fabricated and its performance is studied in harsh environment. Using the authors' previous studies, isolators with optimum properties are selected to ruggedize the chassis containing the cooling chamber against shock and random vibration. Experiments are conducted on both hard-mounted and isolated chassis and the cooling performance of the system is assessed using the inlet, and impingement surface temperatures of the cooling chamber. The experimental results show the isolation system prevents any failure that otherwise would occur, and also does not compromise the thermal performance of the system. - Highlights: • A novel double-chamber jet impingement cooling system was designed and fabricated. • Comprehensive set of random vibration and shock tests are conducted. • The isolation system proved to protect the cooling system properly against mechanical failure. • Cooling system performance was not significantly affected by the input random vibration and shock

Seismological measurement of solar helium abundance

International Nuclear Information System (INIS)

Vorontsov, S.V.; Pamyatnykh, A.A.

1991-01-01

The internal structure and evolution of the Sun depends on its chemical composition, particularly the helium abundance. In addition, the helium abundance in the solar envelope is thought to represent the protosolar value, making it a datum of cosmological significance. Spectroscopic measurements of the helium abundance are uncertain, and the most reliable estimates until now have come from the calibration of solar evolutionary models. The frequencies of solar acoustic oscillations are sensitive, however, to the behaviour of the speed of sound in the Sun's helium ionization zone, which allows a helioseismological determination of the helium abundance. Sound-speed inversion of helioseismological data can be used for this purpose, but precise frequency measurements of high-degree oscillation modes are needed. Here we describe a new approach based on an analysis of the phase shift of acoustic waves of intermediate-degree modes. From the accurate intermediate-mode data now available, we obtain a helium mass fraction Y=0.25±0.01 in the solar convection zone, significantly smaller than the value Y=0.27-0.29 predicted by recent solar evolutionary models. The discrepancy indicates either that initial helium abundance was reduced in the envelope by downward diffusion or that the protosolar value was lower than currently accepted. (author)

Review of Membranes for Helium Separation and Purification

Directory of Open Access Journals (Sweden)

Colin A. Scholes

2017-02-01

Full Text Available Membrane gas separation has potential for the recovery and purification of helium, because the majority of membranes have selectivity for helium. This review reports on the current state of the research and patent literature for membranes undertaking helium separation. This includes direct recovery from natural gas, as an ancillary stage in natural gas processing, as well as niche applications where helium recycling has potential. A review of the available polymeric and inorganic membranes for helium separation is provided. Commercial gas separation membranes in comparable gas industries are discussed in terms of their potential in helium separation. Also presented are the various membrane process designs patented for the recovery and purification of helium from various sources, as these demonstrate that it is viable to separate helium through currently available polymeric membranes. This review places a particular focus on those processes where membranes are combined in series with another separation technology, commonly pressure swing adsorption. These combined processes have the most potential for membranes to produce a high purity helium product. The review demonstrates that membrane gas separation is technically feasible for helium recovery and purification, though membranes are currently only applied in niche applications focused on reusing helium rather than separation from natural sources.

Helium production cross section Measurement of Pb and Sn for 14.9 MeV neutrons

Energy Technology Data Exchange (ETDEWEB)

Takao, Yoshiyuki; Fujimoto, Toshihiro; Ozaki, Shuji; Muramasu, Masatomo; Nakashima, Hideki [Kyushu Univ., Fukuoka (Japan); Kanda, Yukinori; Ikeda, Yujiro

1998-03-01

Helium production cross sections of lead and tin for 14.9 MeV neutrons were measured by helium accumulation method. Lead and tin samples were irradiated with FNS, an intense d-T neutron source of JAERI. The amount of helium produced in the samples by the neutron irradiation was measured with the Helium Atoms Measurement System (HAMS) at Kyushu University. As the samples contained a small amount of helium because of their small helium production cross sections at 14.9 MeV, the samples were evaporated by radiation from a tungsten filament to decrease background gases at helium measurement. Uncertainties of the present results were less than {+-}4.4%. The results were compared with other experimental data in the literature and also compared with the evaluated values in JENDL-3.2. (author)

Generation of stable and low-divergence 10-MeV quasimonoenergetic electron bunch using argon gas jet

Directory of Open Access Journals (Sweden)

M. Mori

2009-08-01

Full Text Available The pointing stability and divergence of a quasimonoenergetic electron bunch generated in a self-injected laser-plasma acceleration regime using 4 TW laser is studied. A pointing stability of 2.4 mrad root-mean-square (rms and a beam divergence of 10.6 mrad (rms were obtained using an argon gas-jet target for 50 sequential shots, while these values were degraded by a factor of 3 at the optimum condition using helium. The peak electron energies were 8.5±0.7 and 24.8±3.6  MeV using argon and helium, respectively. The experimental results indicate that the different propagation condition could be generated with the different material, although it is performed with the same irradiation condition.

Elevated temperature and high pressure large helium gas loop

International Nuclear Information System (INIS)

Sakasai, Minoru; Midoriyama, Shigeru; Miyata, Toyohiko; Nakase, Tsuyoshi; Izaki, Makoto

1979-01-01

The development of high temperature gas-cooled reactors especially aiming at the multi-purpose utilization of nuclear heat energy is carried out actively in Japan and West Germany. In Japan, the experimental HTGR of 50 MWt and 1000 deg C outlet temperature is being developed by Japan Atomic Energy Research Institute and others since 1969, and the development of direct iron-making technology utilizing high temperature reducing gas was started in 1973 as the large project of Ministry of Internalional Trade and Industry. Kawasaki Heavy Industries, Ltd., Has taken part in these development projects, and has developed many softwares for nuclear heat design, system design and safety design of nuclear reactor system and heat utilization system. In hardwares also, efforts have been exerted to develop the technologies of design and manufacture of high temperature machinery and equipments. The high temperature, high pressure, large helium gas loop is under construction in the technical research institute of the company, and it is expected to be completed in December, 1979. The tests planned are that of proving the dynamic performances of the loop and its machinery and equipments and the verification of analysis codes. The loop is composed of the main circulation system, the objects of testing, the helium gas purifying system, the helium supplying and evacuating system, instruments and others. (Kako, I.)

High level helium leak testing methods developed at ICSI Rm. Valcea

International Nuclear Information System (INIS)

Saros, Gili; Armeanu, Adrian; Saros, Irina; Ciortea, Constantin

2007-01-01

Full text: Helium leak detection is one of the most widely used methods of nondestructive testing in use today. In principle two methods are applied for leak testing and localization of leaks, the 'Vacuum method' and the 'Overpressure method'. In case of the 'Vacuum method' the object to be examined for leaks is evacuated and filled instead with Helium. The gas penetrates through any leaks found in the object and is detected by the leak test instrument. In case of the 'Overpressure method' the object to be examined for leaks is filled with Helium, under slight overpressure. The gas escapes through any leaks present and it is detected by a detector probe. This detector probe sometimes called a 'sniffer' acting as a gas sampling probe. Varian 979 Helium Leak Detector has a built-in turbo pump and an externally mounted dry forepump located below the system. The leak detector is configured for the evacuation type leak testing. In this case, the vacuum system under test is evacuated by the leak detector. Helium is then sprayed on the outside of the vacuum system and is pumped into the leak detector if a leak is present. The leak detector is capable to detect leaks down to 10 -9 atm-cc/sec range. The Specton 300E is a strong, rugged leak detector designed to operate in dirty industrial conditions as well as clean research areas. A number of applications are mentioned: - Generators; - Buried Pipelines; - Chemical and power plants; - Vacuum furnace installations; - Heat Exchangers; - Tank Floors; - Nuclear research centers; - Refrigeration installations; - Any type of industrial vacuum system. (authors)

Numerical simulation on stir system of jet ballast in high level liquid waste storage tank

International Nuclear Information System (INIS)

Lu Yingchun

2012-01-01

The stir system of jet ballast in high level liquid waste storage tank was simulation object. Gas, liquid and solid were air, sodium nitrate liquor and titanium whitening, respectively. The mathematic model based on three-fluid model and the kinetic theory of particles was established for the stir system of jet ballast in high level liquid waste storage tank. The CFD commercial software was used for solving this model. The detail flow parameters as three phase velocity, pressure and phase loadings were gained. The calculated results agree with the experimental results, so they can well define the flow behavior in the tank. And this offers a basic method for the scale-up and optimization design of the stir system of jet ballast in high level liquid waste storage tank. (author)

Applying rotary jet heads for mixing and mass transfer in a forced recirculation tank reactor system

DEFF Research Database (Denmark)

Nordkvist, Mikkel; Grotkjær, Thomas; Hummer, J.S.

2003-01-01

or an external loop.In this study, we determine mixing times in water and CMC solutions and oxygen mass transfer coefficients in water for a tank reactor system where a small fraction of the total liquid volume is rapidly circulated through an external loop and injected through the nozzles of rotary jet heads....... The system has a very simple design with no internal baffles or heat exchange area, and between batches the rotary jet heads are used for cleaning in place.Mixing time decreases and mass transfer increases with increasing circulation flow rate. For nozzle diameters between 5.5 and 10 mm and with one or two...... rotary jet heads, it is shown that a remarkable saving in power input for a fixed mixing time or mass transfer coefficient can be obtained by using a large nozzle diameter and two rather than one rotary jet heads.At the experimental conditions of the study the system is scaleable by simple formulas...

EDITORIAL: Plasma jets and plasma bullets Plasma jets and plasma bullets

Science.gov (United States)

Kong, M. G.; Ganguly, B. N.; Hicks, R. F.

2012-06-01

to material processing applications, possibly because chaotic patterns of reaction chemistry could be undesirable for sample-sample reproducibility of application efficacy. Nevertheless, the lack of reproducibility in the presence of chaos may actually offer an advantage in tackling drug resistance in the new field of plasma medicine. As a material processing tool, it is important to characterize the reaction chemistry of plasma jets at a downstream point. Four special issue papers report measurement of argon and helium metastable atoms, ozone, oxygen atoms and UV irradiation using a variety of diagnostic tools including laser absorption spectroscopy, molecular beam mass spectrometry, optical emission and UV absorption spectrometry [32]-[35]. There is, however, a gap in these measurements of key reactive plasma species and characterization of plasma bullet formation [20]-[26], both in this special issue and elsewhere in the literature. Whilst atmospheric plasma modes are known to operate in bullet and non-bullet modes, it is unclear whether electron excitation of helium and/or argon metastables is different in the bullet mode from the non-bullet mode. Similarly, it remains little known whether the bullet mode facilitates a particularly efficient production of reactive plasma species [36]. An encouraging sign of our ability to address this and other knowledge gaps is evident from three excellent modelling investigations, looking into the behaviours of ionization waves [37], interaction of two counter-propagating streamers [38], and the two-dimensional structure of streamers [39]. Considerable detail unravelled from these and similar simulation studies is likely to not only uncover the physics of plasma bullet formation, but also link it to the design and manipulation of downstream reaction chemistry. In fact, very recent studies have combined experimental characterization of plasma jets with their numerical modelling [40].

Acceptance test procedure for High Pressure Water Jet System

International Nuclear Information System (INIS)

Crystal, J.B.

1995-01-01

The overall objective of the acceptance test is to demonstrate a combined system. This includes associated tools and equipment necessary to perform cleaning in the 105 K East Basin (KE) for achieving optimum reduction in the level of contamination/dose rate on canisters prior to removal from the KE Basin and subsequent packaging for disposal. Acceptance tests shall include necessary hardware to achieve acceptance of the cleaning phase of canisters. This acceptance test procedure will define the acceptance testing criteria of the high pressure water jet cleaning fixture. The focus of this procedure will be to provide guidelines and instructions to control, evaluate and document the acceptance testing for cleaning effectiveness and method(s) of removing the contaminated surface layer from the canister presently identified in KE Basin. Additionally, the desired result of the acceptance test will be to deliver to K Basins a thoroughly tested and proven system for underwater decontamination and dose reduction. This report discusses the acceptance test procedure for the High Pressure Water Jet

Economics of Large Helium Cryogenic Systems experience from Recent Projects at CERN

CERN Document Server

Claudet, S; Lebrun, P; Tavian, L; Wagner, U

1999-01-01

Large projects based on applied superconductivity, such as particle accelerators, tokamaks or SMES, require powerful and complex helium cryogenic systems, the cost of which represents a significant, if not dominant fraction of the total capital and operational expenditure. It is therefore important to establish guidelines and scaling laws for costing such systems, based on synthetic estimators of their size and performance. Although such data has already been published for many years, the experience recently gathered at CERN with the LEP and LHC projects, which have de facto turned the laboratory into a major world cryogenic center, can be exploited to update this information and broaden the range of application of the scaling laws. We report on the economics of 4.5 K and 1.8 K refrigeration, cryogen distribution and storage systems, and indicate paths towards their cost-to-performance optimisation.

Supersonic Combustion of Hydrogen Jets System in Hypersonic Stream

International Nuclear Information System (INIS)

Zhapbasbaev, U.K.; Makashev, E.P.

2003-01-01

The data of calculated theoretical investigations of diffusive combustion of plane supersonic hydrogen jets in hypersonic stream received with Navier-Stokes parabola equations closed by one-para metrical (k-l) model of turbulence and multiply staged mechanism of hydrogen oxidation are given. Combustion mechanisms depending on the operating parameters are discussing. The influences of air stream composition and ways off fuel feed to the length of ignition delay and level quantity of hydrogen bum-out have been defined. The calculated theoretical results of investigations permit to make the next conclusions: 1. The diffusive combustion of the system of plane supersonic hydrogen jets in hypersonic flow happens in the cellular structures with alternation zones of intensive running of chemical reactions with their inhibition zones. 2. Gas dynamic and heat Mach waves cause a large - scale viscous formation intensifying mixing of fuel with oxidizer. 3. The system ignition of plane supersonic hydrogen jets in hypersonic airy co-flow happens with the formation of normal flame front of hydrogen airy mixture with transition to the diffusive combustion. 4. The presence of active particles in the flow composition initiates the ignition of hydrogen - airy mixture, provides the intensive running of chemical reactions and shortens the length of ignition delay. 5. The supersonic combustion of hydrogel-airy mixture is characterized by two zones: the intensive chemical reactions with an active energy heat release is occurring in the first zone and in the second - a slow hydrogen combustion limited by the mixing of fuel with oxidizer. (author)

Safety in handling helium and nitrogen

International Nuclear Information System (INIS)

Schmauch, G.; Lansing, L.; Santay, T.; Nahmias, D.

1991-01-01

Based upon the authors' industrial experience and practices, they have provided an overview of safety in storage, handling, and transfer of both laboratory and bulk quantities of gaseous and liquid forms of nitrogen and helium. They have addressed the properties and characteristics of both the gaseous and liquid fluids, typical storage and transport containers, transfer techniques, and the associated hazards which include low temperatures, high pressures, and asphyxiation. Methods and procedures to control and eliminate these hazards are described, as well as risk remediation through safety awareness training, personal protective equipment, area ventilation, and atmosphere monitoring. They have included as an example a recent process hazards analysis performed by Air Products on the asphyxiation hazard associated with the use of liquid helium in MRI magnet systems

Nuclear fuel rod helium leak inspection apparatus and method

International Nuclear Information System (INIS)

Ahmed, H.J.

1991-01-01

This patent describes an inspection apparatus for testing nuclear fuel rods for helium leaks. It comprises a test chamber being openable and closable for receiving at least one nuclear fuel rod; means separate from the fuel rod for supplying helium and constantly leaking helium at a predetermined known positive value into the test chamber to constantly provide an atmosphere of helium at the predetermined known positive value in the test chamber; and means for sampling the atmosphere within the chamber and measuring the helium in the atmosphere such that a measured helium value below a preset minimum helium value substantially equal to the predetermined known positive value of the atmosphere of helium being constantly provided in the test chamber indicates a malfunction in the inspection apparatus, above a preset maximum helium value greater than the predetermined known positive in the test chamber indicates the existence of a helium leak from the fuel rod, or between the preset minimum and maximum helium values indicates the absence of a helium leak from the fuel rod

Helium behaviour in implanted boron carbide

Directory of Open Access Journals (Sweden)

Motte Vianney

2015-01-01

Full Text Available When boron carbide is used as a neutron absorber in nuclear power plants, large quantities of helium are produced. To simulate the gas behaviour, helium implantations were carried out in boron carbide. The samples were then annealed up to 1500 °C in order to observe the influence of temperature and duration of annealing. The determination of the helium diffusion coefficient was carried out using the 3He(d,p4He nuclear reaction (NRA method. From the evolution of the width of implanted 3He helium profiles (fluence 1 × 1015/cm2, 3 MeV corresponding to a maximum helium concentration of about 1020/cm3 as a function of annealing temperatures, an Arrhenius diagram was plotted and an apparent diffusion coefficient was deduced (Ea = 0.52 ± 0.11 eV/atom. The dynamic of helium clusters was observed by transmission electron microscopy (TEM of samples implanted with 1.5 × 1016/cm2, 2.8 to 3 MeV 4He ions, leading to an implanted slab about 1 μm wide with a maximum helium concentration of about 1021/cm3. After annealing at 900 °C and 1100 °C, small (5–20 nm flat oriented bubbles appeared in the grain, then at the grain boundaries. At 1500 °C, due to long-range diffusion, intra-granular bubbles were no longer observed; helium segregates at the grain boundaries, either as bubbles or inducing grain boundaries opening.

Dynamic simulation for scram of high temperature gas-cooled reactor with indirect helium turbine cycle system

International Nuclear Information System (INIS)

Li Wenlong; Xie Heng

2011-01-01

A dynamic analysis code for this system was developed after the mathematical modeling and programming of important equipment of 10 MW High Temperature Gas Cooled Reactor Helium Turbine Power Generation (HTR-10GT), such as reactor core, heat exchanger and turbine-compressor system. A scram accident caused by a 0.1 $ reactivity injection at 5 second was simulated. The results show that the design emergency shutdown plan for this system is safe and reasonable and that the design of bypass valve has a large safety margin. (authors)

Modeling the pressure increase in liquid helium cryostats after failure of the insulating vacuum

Energy Technology Data Exchange (ETDEWEB)

Heidt, C.; Grohmann, S. [Karlsruhe Institute of Technology, Institute for Technical Physics, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany and Karlsruhe Institute of Technology, Institute for Technical Thermodynamics and Refrigeration, Engler-Bunte (Germany); Süßer, M. [Karlsruhe Institute of Technology, Institute for Technical Physics, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany)

2014-01-29

The pressure relief system of liquid helium cryostats requires a careful design, due to helium's low enthalpy of vaporization and due to the low operating temperature. Hazard analyses often involve the failure of the insulating vacuum in the worst-case scenario. The venting of the insulating vacuum and the implications for the pressure increase in the helium vessel, however, have not yet been fully analyzed. Therefore, the dimensioning of safety devices often requires experience and reference to very few experimental data. In order to provide a better foundation for the design of cryogenic pressure relief systems, this paper presents an analytic approach for the strongly dynamic process induced by the loss of insulating vacuum. The model is based on theoretical considerations and on differential equation modeling. It contains only few simplifying assumptions, which will be further investigated in future experiments. The numerical solutions of example calculations are presented with regard to the heat flux into the helium vessel, the helium pressure increase and the helium flow rate through the pressure relief device. Implications concerning two-phase flow and the influence of kinetic energy are discussed.

Experimental evidence of the statistical intermittency in a cryogenic turbulent jet of normal and superfluid Helium

International Nuclear Information System (INIS)

Duri, D.

2012-01-01

This experimental work is focused on the statistical study of the high Reynolds number turbulent velocity field in an inertially driven liquid helium axis-symmetric round jet at temperatures above and below the lambda transition (between 2.3 K and 1.78 K) in a cryogenic wind tunnel. The possibility to finely tune the fluid temperature allows us to perform a comparative study of the quantum He II turbulence within the classical framework of the Kolmogorov turbulent cascade in order to have a better understanding of the energy cascade process in a superfluid. In particular we focused our attention on the intermittency phenomena, in both He I and He II phases, by measuring the high order statistics of the longitudinal velocity increments by means of the flatness and the skewness statistical estimators. A first phase consisted in developing the cryogenic facility, a closed loop pressurized and temperature regulated wind tunnel, and adapting the classic hot-wire anemometry technique in order to be able to work in such a challenging low temperature environment. A detailed calibration procedure of the fully developed turbulent flow was the carried out at 2.3 K at Reynolds numbers based on the Taylor length scale up to 2600 in order to qualify our testing set-up and to identify possible facility-related spurious phenomena. This procedure showed that the statistical properties of the longitudinal velocity increments are in good agreement with respect to previous results. By further reducing the temperature of the working fluid (at a constant pressure) below the lambda point down to 1.78 K local velocity measurements were performed at different superfluid density fractions. The results show a classic behaviour of the He II energy cascade at large scales while, at smaller scales, a deviation has been observed. The occurrence of this phenomenon, which requires further investigation and modelling, is highlighted by the observed changing sign of the third order structure

The design of an isotope separation system for JET

International Nuclear Information System (INIS)

Sherman, R.H.

1987-10-01

Cryogenic distillation is planned as one of the processes to be used for isotope separation at JET. Three possible configurations of columns for this service are presented and discussed. The ability to easily control a system of columns must weigh heavily in the final selection of a process for construction. 5 refs., 6 figs., 6 tabs

Technologies of 1.8 K / 2.4 kW helium refrigerators and cold compressors for LHC

International Nuclear Information System (INIS)

Saji, Nobuyoshi; Yoshinaga, Seiichirou; Asakura, Hiroshi; Shimba, Toru; Honda, Tadaaki; Mori, Mikio

2005-01-01

For the LHC (Large Hadron Collider) project of the CERN (Conseil Europeen pour la Recherche Nucleaire), the Swiss-Japanese consortium IHI/Linde Kryotechnik AG delivered a 1.8 K helium refrigeration system. Linde has produced many helium refrigeration systems and IHI has designed and manufactured cold compressors that utilize many advanced technologies and innovative ideas for turbo machinery. The compressor has the characteristics of the highest efficiency in the world. This paper describes the 1.8 K helium refrigeration system and performance test results at CERN. (author)

Helium behaviour in aluminium under hydrostatic pressure

International Nuclear Information System (INIS)

Sokurskij, Yu.N.; Tebus, V.N.; Zudilin, V.A.; Tumanova, G.M.

1989-01-01

Effect of hydrostatic compression on equilibrium helium bubbles in low aluminium-lithium alloy irradiated in reactor at 570 K is investigated. Measurements of hydrostatic density and electron-microscopic investigations have shown, that application of up to 2 GPa pressure reduces equilibrium size of helium bubbles and reduces helium swelling. Kinetics and thermodynamics of the process are considered with application of 'rigid sphere' equation which describes helium state in bubbles

Feasibility of high-helium natural gas exploration in the Presinian strata, Sichuan Basin

Directory of Open Access Journals (Sweden)

Jian Zhang

2015-01-01

Full Text Available Helium in China highly depends on import at present, so the most practical way to change the situation is searching for medium-to-large natural gas fields with high helium content. Therefore, the hydrocarbon accumulation mechanism and the helium origin of the Weiyuan high-helium natural gas reservoir have been analyzed to find out the feasibility of finding natural gas field with high helium content in the Presinian strata of the Sichuan Basin. Based on twelve outcrop sections and drilling data of four wells encountering the Presinian strata, the petrological features, sedimentary facies and source rocks of Presinian strata were systematically analyzed, which shows that the sedimentary formation developed in the Presinian is the Nanhua system, and the stratigraphic sequence revealed by outcrop section in the eastern margin includes the Nantuo, Datangpo, Gucheng and Liantuo Fms, and it is inferred that the same stratigraphic sequence may occur inside the basin. The Nantuo, Gucheng and Liantuo Fms are mainly glacial deposits of glutenite interbedded with mudstone; the Datangpo Fm is interglacial deposits of sandstone and shale, the lower part shale, rich in organic matter, is fairly good source rock. Further study showed that the Nantuo coarse-grained clastic reservoir, Datangpo source rock and the intruded granite “helium source rock” make up a good high-helium gas system. Controlled by the early rift, the thick Presinian sedimentary rocks occur primarily inside the rift. The distribution of sedimentary rocks and granite in the basin was predicted by use of the seismic data, which shows that the feasibility of finding high-helium gas reservoirs in Ziyang area of the Sichuan Basin is great.

Nucleation path of helium bubbles in metals during irradiation

International Nuclear Information System (INIS)

Morishita, Kazunori

2008-01-01

Thermodynamical formalization is made for description of the nucleation and growth of helium bubbles in metals during irradiation. The proposed formalization is available or evaluating both microstructural changes in fusion first wall materials where helium is produced by (n, α) nuclear transmutation reactions, and those in fusion divertor materials where helium particles with low energy are directly implanted. Calculated nucleation barrier is significantly reduced by the presence of helium, showing that a helium bubble with an appropriate number of helium atoms depending on bubble size can nucleate without any large nucleation barriers, even at a condition where an empty void has very large nucleation barrier without helium. With the proposed thermodynamical formalization, the nucleation and growth process of helium bubbles in iron during irradiation is simulated by the kinetic Monte-Carlo (KMC) technique. It shows the nucleation path of a helium bubble on the (N He , N V ) space as functions of temperatures and the concentration of helium in the matrix, where N He and N V are the number of helium atoms and vacancies in the helium bubble, respectively. Bubble growth rates depend on the nucleation path and suggest that two different mechanisms operate for bubble growth: one is controlled by vacancy diffusion and the other is controlled by interstitial helium diffusion. (author)

Helium mobility in advanced nuclear ceramics

International Nuclear Information System (INIS)

Agarwal, Shradha

2014-01-01

The main goal of this work is to improve our knowledge on the mechanisms able to drive the helium behaviour in transition metal carbides and nitrides submitted to thermal annealing or ion irradiation. TiC, TiN and ZrC polycrystals were implanted with 3 MeV 3 He ions at room temperature in the fluence range 2 * 10 15 et 6 * 10 16 cm -2 . Some of them have been pre-irradiated with self-ions (14 MeV Ti or Zr). Fully controlled thermal annealing tests were subsequently carried out in the temperature range 1000 - 1600 C for two hours. The evolution of the helium depth distribution in function of implantation dose, temperature and pre-irradiation dose was measured thanks to the deuteron-induced nuclear reaction 3 He(d, p 0 ) 4 He between 900 keV and 1.8 MeV. The microstructure of implanted and annealed samples was investigated by transmission electron microscopy on thin foils prepared using the FIB technique. Additional characterization tools, as X-ray diffraction and Raman microspectrometry, have been also applied in order to obtain complementary information. Among the most relevant results obtained, the following have to be outlined: - double-peak helium depth profile was measured on as implanted sample for the three compounds. The first peak is located near the end of range and includes the major part of helium, a second peak located close to the surface corresponds to the helium atoms trapped by the native vacancies; - the helium retention capacity in transition metal carbides and nitrides submitted to fully controlled thermal treatments varies according to ZrC 0.92 ≤ TiC 0.96 ≤ TiN 0.96 ; - whatever the investigated material, a self-ion-induced pre-damaging does not modify the initial helium profile extent. The influence of the post-implantation thermal treatment remains preponderant in any case; - the apparent diffusion coefficient of helium is in the range 4 * 10 -18 - 2 * 10 -17 m 2 s -1 in TiC0.96 and 3.5 * 10 -19 - 5.3 * 10 -18 m 2 s -1 in TiN 0.96 between

Impulse approximation in solid helium

International Nuclear Information System (INIS)

Glyde, H.R.

1985-01-01

The incoherent dynamic form factor S/sub i/(Q, ω) is evaluated in solid helium for comparison with the impulse approximation (IA). The purpose is to determine the Q values for which the IA is valid for systems such a helium where the atoms interact via a potential having a steeply repulsive but not infinite hard core. For 3 He, S/sub i/(Q, ω) is evaluated from first principles, beginning with the pair potential. The density of states g(ω) is evaluated using the self-consistent phonon theory and S/sub i/(Q,ω) is expressed in terms of g(ω). For solid 4 He resonable models of g(ω) using observed input parameters are used to evaluate S/sub i/(Q,ω). In both cases S/sub i/(Q, ω) is found to approach the impulse approximation S/sub IA/(Q, ω) closely for wave vector transfers Q> or approx. =20 A -1 . The difference between S/sub i/ and S/sub IA/, which is due to final state interactions of the scattering atom with the remainder of the atoms in the solid, is also predominantly antisymmetric in (ω-ω/sub R/), where ω/sub R/ is the recoil frequency. This suggests that the symmetrization procedure proposed by Sears to eliminate final state contributions should work well in solid helium

Effect of helium on void swelling in vanadium

International Nuclear Information System (INIS)

Brimhall, J.L.; Simonen, E.P.

1975-01-01

Little difference in void microstructural swelling of vanadium is observed when helium is injected simultaneously with a 46- or 5-MeV nickel beam as compared to no helium injection, at least at high dose rates. At lower dose rates, a strong helium effect is seen when the helium is injected prior to heavy ion bombardment. The effect of the helium is shown to be a strong function of the overall displacement damage rate

Computational fluid dynamics (CFD) in the design of a water-jet-drive system

Science.gov (United States)

Garcia, Roberto

1994-01-01

NASA/Marshall Space Flight Center (MSFC) has an ongoing effort to transfer to industry the technologies developed at MSFC for rocket propulsion systems. The Technology Utilization (TU) Office at MSFC promotes these efforts and accepts requests for assistance from industry. One such solicitation involves a request from North American Marine Jet, Inc. (NAMJ) for assistance in the design of a water-jet-drive system to fill a gap in NAMJ's product line. NAMJ provided MSFC with a baseline axial flow impeller design as well as the relevant working parameters (rpm, flow rate, etc.). This baseline design was analyzed using CFD, and significant deficiencies identified. Four additional analyses were performed involving MSFC changes to the geometric and operational parameters of the baseline case. Subsequently, the impeller was redesigned by NAMJ and analyzed by MSFC. This new configuration performs significantly better than the baseline design. Similar cooperative activities are planned for the design of the jet-drive inlet.

Microplasma jet treatment of bovine serum albumin coatings for controlling enzyme and cell attachmenttype="fn" rid="FN1">

Science.gov (United States)

Szili, Endre J.; Becker, Stefanie; Short, Robert D.; Al-Bataineh, Sameer A.

2017-08-01

We investigated a new approach to control protein and cell attachment inside 96-well polystyrene plates. The wells were first coated with bovine serum albumin (BSA) to inhibit cell and protein attachment. The BSA-coated wells were then treated with a helium microplasma jet for increasing times that resulted in gradual removal of BSA from the surface. It was found that the amount of enzyme and cell attachment could be controlled in the wells where BSA was only partially removed by the microplasma jet. In addition to the surface coverage of BSA, the new surface chemistry induced by the microplasma jet treatment also had an important role in the control of enzyme and cell attachment. In summary, microplasma jet treatment of BSA-coated polystyrene wells is a simple and effective method for controlling enzyme and cell attachment. This might find use for high-throughput screening of new cell culture platforms where control over the level protein, enzyme or cell adherence is needed in order to maintain a specific cell function.

The evolution of real-time control systems at JET

Energy Technology Data Exchange (ETDEWEB)

Goodyear, A.; Dorling, S.; Felton, R

2001-07-01

Real-time feedback control of the JET experiment is based upon a collection of diagnostics providing signals which are processed by various controllers that manipulate actuator parameters for plasma current, shape and heating. The real-time data network (RTDN) connects the diagnostic, controller and actuator systems to form a flexible feedback and protection system for plasma monitoring and control. The controllers are mainly VME systems based on the Motorola 680X0 (68K) processor with some computationally intensive systems utilising Texas Instruments TMS320C40 (C40) digital signal processors (DSP), though lately there has been a move towards PowerPC 750 based processors. The majority of 68K VME systems use VxWorks, a hard real time operating system. There is an ongoing requirement to improve the efficiency of the real-time control systems at JET. This is driven by a desire to either add more input signals, reduce the feedback cycle time or increase algorithm complexity. New technology has a major role to play in the upgrade of the real-time control systems but the novel redeployment of existing equipment can also be used to enhance performance. This paper examines the configuration of existing systems, both hardware and software, and how new technology can be gradually integrated without jeopardising the current functionality. The adoption of Asynchronous Transfer Mode (ATM) as the connection medium for the RTDN is key to the evolutional development of the control systems. The ATM network is extremely flexible to configure and benefits from low message latency and deterministic delivery time, essential properties for a real-time network. (author)

Clustering of Helium Atoms at a ½

NARCIS (Netherlands)

Berg, F. v.d.; Heugten, W. v.; Caspers, L.M.; Veen, A. v.; Hosson, J.Th.M. de

1977-01-01

Atomistic calculations on a ½<111>{110} edge dislocation show a restricted tendency of clustering of helium atom along this dislocation. Clusters with up to 4 helium atoms have been studied. A cluster with 3 helium proved to be most stable.

The upgraded JET toroidal Alfvén eigenmode diagnostic system

Science.gov (United States)

Puglia, P.; Pires de Sa, W.; Blanchard, P.; Dorling, S.; Dowson, S.; Fasoli, A.; Figueiredo, J.; Galvão, R.; Graham, M.; Jones, G.; Perez von Thun, C.; Porkolab, M.; Ruchko, L.; Testa, D.; Woskov, P.; Albarracin-Manrique, M. A.; Contributors, JET

2016-11-01

The main characteristics of toroidal Alfvén eigenmodes (TAEs) have been successfully investigated in JET (Joint European Torus) using the scheme of sweeping-frequency external excitation with tracking of the synchronously-detected resonances. However, due to technical limitations, only modes with low values of the toroidal mode number n≤slant 7 could be effectively excited and unambiguously identified by the Alfvén Eigenmode Active Diagnostic (AEAD) system. This represents a serious restriction because theoretical models indicate that medium-n Alfvén eigenmodes (AEs) are the most prone to be destabilized by energetic particles in ignited plasmas and, therefore, reliable measurement of their damping rates remains a relevant issue to properly access their effect in ignited plasmas. For this reason, a major upgrade of the AEAD system has been carried out aiming at providing a state-of-the-art excitation and real-time detection system for the planned DT campaign in JET. This required the development of a new type of radio frequency amplifier and filter, not commercially available, and also a control system. In this paper, details of the concepts that are relevant to understand the operation of the new system in the next experimental campaigns are presented, as are the results of numerical simulations to model its performance.

Effect of helium on void formation in nickel

International Nuclear Information System (INIS)

Brimhall, J.L.; Simonen, E.P.

1977-01-01

This study examines the influence of helium on void formation in self-ion irradiated nickel. Helium was injected either simultaneously with, or prior to, the self-ion bombardment. The void microstructure was characterized as a function of helium deposition rate and the total heavy-ion dose. In particular, at 575 0 C and 5 X 10 -3 displacements per atom per second the void density is found to be proportional to the helium deposition rate. The dose dependence of swelling is initially dominated by helium driven nucleation. The void density rapidly saturates after which swelling continues with increasing dose only from void growth. It is concluded that helium promotes void nucleation in nickel with either helium implantation technique, pre-injection or simultaneous injection. Qualitative differences, however, are recognized. (Auth.)

Commercial helium reserves, continental rifting and volcanism

Science.gov (United States)

Ballentine, C. J.; Barry, P. H.; Hillegonds, D.; Fontijn, K.; Bluett, J.; Abraham-James, T.; Danabalan, D.; Gluyas, J.; Brennwald, M. S.; Pluess, B.; Seneshens, D.; Sherwood Lollar, B.

2017-12-01

Helium has many industrial applications, but notably provides the unique cooling medium for superconducting magnets in medical MRI scanners and high energy beam lines. In 2013 the global supply chainfailed to meet demand causing significant concern - the `Liquid Helium Crisis' [1]. The 2017 closure of Quatar borders, a major helium supplier, is likely to further disrupt helium supply, and accentuates the urgent need to diversify supply. Helium is found in very few natural gas reservoirs that have focused 4He produced by the dispersed decay (a-particle) of U and Th in the crust. We show here, using the example of the Rukwa section of the Tanzanian East African Rift, how continental rifting and local volcanism provides the combination of processes required to generate helium reserves. The ancient continental crust provides the source of 4He. Rifting and associated magmatism provides the tectonic and thermal mechanism to mobilise deep fluid circulation, focusing flow to the near surface along major basement faults. Helium-rich springs in the Tanzanian Great Rift Valley were first identified in the 1950's[2]. The isotopic compositions and major element chemistry of the gases from springs and seeps are consistent with their release from the crystalline basement during rifting [3]. Within the Rukwa Rift Valley, helium seeps occur in the vicinity of trapping structures that have the potential to store significant reserves of helium [3]. Soil gas surveys over 6 prospective trapping structures (1m depth, n=1486) show helium anomalies in 5 out of the 6 at levels similar to those observed over a known helium-rich gas reservoir at 1200m depth (7% He - Harley Dome, Utah). Detailed macroseep gas compositions collected over two days (n=17) at one site allows us to distinguish shallow gas contributions and shows the deep gas to contain between 8-10% helium, significantly increasing resource estimates based on uncorrected values (1.8-4.2%)[2,3]. The remainder of the deep gas is

A solution for the helium problem. Cryogen-free cooling systems for low temperatures; Eine Loesung fuer das Heliumproblem. Kryogenfreie Kuehlsysteme fuer tiefe Temperaturen

Energy Technology Data Exchange (ETDEWEB)

Good, Jeremy [Cryogenic Limited, London (United Kingdom)

2014-09-15

Pulse tube or Gifford-McMahon coolers are related to Stirling engines. Extremely low temperatures - 1 K can be reached with these devices. As a cryogen-free system the devices need only small amounts of helium as working gas. This fact reduces the gaseous and liquid helium consumption of research labs considerably and allows new applications. The cost-efficiency of this alternative technique is important for research facilities that use superconducting magnets.

Neutronic calculations for JET. Performed with the FURNACE2 program. (Final report JET contract JEO/9004)

International Nuclear Information System (INIS)

Verschuur, K.A.

1996-10-01

Neutron-transport calculations with the FURNACE(2) program system, in support of the Neutron Diagnostic Group at JET, have been performed since 1980, i.e. since the construction phase of JET. FURNACE(2) is a ray-tracing/multiple-reflection transport program system for toroidal geometries, that orginally was developed for blanket neutronics studies and which then was improved and extended for application to the neutron-diagnostics at JET. (orig./WL)

A compact quadrupole ion filter for helium detection

International Nuclear Information System (INIS)

Pereira, E.B.

1981-01-01

A compact quadrupole ion filter was conceived and constructed for optimum performance at the mass four region of the mass spectra. It was primarely designed for geological applications in the measurements of helium of soil-gases. The whole ion filter structure is 15 cm long by 3.5 cm diameter, including ion source and collecting plate. The sensitivity to helium is of the order of 10 - 2 A.torr - 1 measured at a total pressure of 6x10 - 6 torr and resolution 6. The system can be easily adapted to work as a dynamic residual gas analyser for other purposes. (Author) [pt

Mass spectrometric analysis of helium in stainless steel

International Nuclear Information System (INIS)

Isagawa, Hiroto; Wada, Yukio; Asakura, Yoshiro; Tsuji, Nobuo; Sato, Hitoshi; Tsutsumi, Kenichi

1974-01-01

Vacuum fusion mass-spectrometry was adopted for the analysis of helium in stainless steel. Samples were heated in a vacuum crucible, and helium in the samples was extracted and collected into a reservoir tank. The gas was then introduced through an orifice into a mass spectrometer, where the amount of helium was determined. The maspeq 070 quadrupole type mass spectrometer made by Shimazu Seisakusho, Ltd. was used. The resolving power was 150, and the mass range of the apparatus was 0-150. The determination limit of helium was about 2 x 10 -3 μg when standard helium gas was analyzed, and was about 10 -2 μg when the helium in stainless steel was analyzed. The relative standard deviation of helium intensity in repetitive measurement was about 2% in the amount of helium of 0.05 μg. Helium was injected into stainless steel by means of alpha particle irradiation with a cyclotron. The amount of helium in stainless steel was then determined. The energy of alpha particles was 34 MeV, and the beam area was 10 mm x 10 mm. The experimental data were higher than the expected value in one case, and were lower in the other case. This difference was attributable to the fluctuation of alpha particle beam, misplacement of sample plates, and unevenness of the alpha beam. (Fukutomi, T.)

Design and operation of remote maintenance systems in JET

International Nuclear Information System (INIS)

Raimondi, T.

1987-01-01

The JET tokamak is a joint European project aimed at proving the viability of nuclear fusion as a source of energy. A remote handling system is being developed for this large experimental facility. Force feedback servomanipulators and TV cameras are positioned at work locations by large transporters. Positioning and tele-operation are computer-assisted. Special tools are being devised to facilitate difficult tasks

The near infrared imaging system for the real-time protection of the JET ITER-like wall

Science.gov (United States)

Huber, A.; Kinna, D.; Huber, V.; Arnoux, G.; Balboa, I.; Balorin, C.; Carman, P.; Carvalho, P.; Collins, S.; Conway, N.; McCullen, P.; Jachmich, S.; Jouve, M.; Linsmeier, Ch; Lomanowski, B.; Lomas, P. J.; Lowry, C. G.; Maggi, C. F.; Matthews, G. F.; May-Smith, T.; Meigs, A.; Mertens, Ph; Nunes, I.; Price, M.; Puglia, P.; Riccardo, V.; Rimini, F. G.; Sergienko, G.; Tsalas, M.; Zastrow, K.-D.; contributors, JET

2017-12-01

This paper describes the design, implementation and operation of the near infrared (NIR) imaging diagnostic system of the JET ITER-like wall (JET-ILW) plasma experiment and its integration into the existing JET protection architecture. The imaging system comprises four wide-angle views, four tangential divertor views, and two top views of the divertor covering 66% of the first wall and up to 43% of the divertor. The operation temperature ranges which must be observed by the NIR protection cameras are, for the materials used on JET: Be 700 °C-1400 °C W coating 700 °C-1370 °C W bulk 700 °C-1400 °C. The Real-Time Protection system operates routinely since 2011 and successfully demonstrated its capability to avoid the overheating of the main chamber beryllium wall as well as of the divertor W and W-coated carbon fibre composite (CFC) tiles. During this period, less than 0.5% of the terminated discharges were aborted by a malfunction of the system. About 2%-3% of the discharges were terminated due to the detection of actual hot spots.

Preliminary study on application of Pd composite membrane in helium purification system of high-temperature gas-cooled reactor