Intensities of decimetric-wavelength radio recombination lines

International Nuclear Information System (INIS)

Parrish, A.; Pankonin, V.

1975-01-01

We summarize the intensity results of some of the 221 and 248α recombination-line observations taken with the Arecibo telescope, and report additional results including 166α observations from the NRAO 300-foot (91 m) telescope. The brightness temperatures of these lines increase sharply with wavelength. We show that these results require that the upper levels of the recombining atoms be overpopulated with respect to LTE conditions. The most reasonable interpretation of the results is that the line emission at these decimetric wavelengths is stimulated by a background source of continuum radiation

The helium line formation in late-type stars: Pt. 1

International Nuclear Information System (INIS)

Batalha, C.C.; De La Reza, R.

1989-01-01

The formation of helium lines and continua in an atmospheric model representing the medium quiet sun has been investigated considering principally the influence of: (i) changes in the temperature gradient at Transition Region (TR); (ii) the coronal radiation and (iii) the overlapping of He II Lyα at 304 A and the continuum radiation of He I at λ≤504 A. By diminishing the thermal gradient in the Transition Region a large part of the helium observations are reproduced. This is the case for the He II resonance λ304 line which is collisionally controlled and is formed at 1.0 x 10 5 K, and the He I resonance line at 584 A which is also collisionally controlled but is formed at deeper layers with a mean temperature of 2.5 x 10 4 K. The He II continuum at 228 A as well as the Lβ line at 256 A can be adjusted to observations if a characteristic solar coronal flux is incident on the optimized Transition Region. (author)

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.

Orion A helium abundance

International Nuclear Information System (INIS)

Tsivilev, A.P.; Ershov, A.A.; Smirnov, G.T.; Sorochenko, R.L.

1986-01-01

The 22.4-GHz (H,He)66-alpha and 36.5-GHz (H,He)56-alpha radio recombination lines have been observed at several Jaffe-Pankonin positions in the central part of the Orion A source. The measured relative abundance of ionized helium increases with distance, averaging 11.6 percent at peripheral points. The observed behavior is interpreted by a blister-type model nebula, which implies that Orion A has a true He abundance of 12 percent, is moving with a radial velocity of 5 km/sec, and is expanding. 18 references

A New Window into Escaping Exoplanet Atmospheres: 10830 Å Line of Helium

Science.gov (United States)

Oklopčić, Antonija; Hirata, Christopher M.

2018-03-01

Observational evidence for escaping exoplanet atmospheres has been obtained for a few exoplanets to date. It comes from strong transit signals detected in the ultraviolet, most notably in the wings of the hydrogen Lyα (Lyα) line. However, the core of the Lyα line is often heavily affected by interstellar absorption and geocoronal emission, limiting the information about the atmosphere that can be extracted from that part of the spectrum. Transit observations in atomic lines that are (a) sensitive enough to trace the rarefied gas in the planetary wind and (b) do not suffer from significant extinction by the interstellar medium could enable more detailed observations, and thus provide better constraints on theoretical models of escaping atmospheres. The absorption line of a metastable state of helium at 10830 Å could satisfy both of these conditions for some exoplanets. We develop a simple 1D model of escaping planetary atmospheres containing hydrogen and helium. We use it to calculate the density profile of helium in the 23S metastable excited state and the expected in-transit absorption at 10830 Å for two exoplanets known to have escaping atmospheres. Our results indicate that exoplanets similar to GJ 436b and HD 209458b should exhibit enhanced transit depths at 10830 Å, with ∼8% and ∼2% excess absorption in the line core, respectively.

Effect of multipulse waveform on gains of soft X-ray lines of lithium-like aluminum ions in recombining plasmas

International Nuclear Information System (INIS)

Okasaka, Kazunobu; Hara, Tamio; Yamaguchi, Naohiro; Ando, Kozo; Kawachi, Tetsuya; Oyama, Hitoshi

2000-01-01

Using the recombination plasma scheme, we investigated the amplified spontaneous emissions (ASE) from lithium-like aluminum plasmas produced by multipulse laser irradiation. Three types of multipulse waveforms of Nd-glass laser beam were treated. We measured the time-integrated intensities of the 3d-4f (15.5 nm) and the 3d-5f (10.6 nm) lines of lithium-like aluminum ions for 2.5-cm-long and 1.25-cm-long plasmas. The effective time-averaged gains estimated from these time-integrated intensities varied with the multipulse waveforms. using a hydrodynamic simulation, we discussed the time history of plasma parameters in the recombining plasma. We concluded that the modifying multipulse waveform contributed to the effective time-averaged gain by maintaining the helium-like ion density until the gain was generated. (author)

Luminescence in Primordial Helium Lines at the Pre-recombination Epoch

Science.gov (United States)

Dubrovich, V. K.; Grachev, S. I.

2018-04-01

The formation of luminescent subordinate He I lines by the absorption of radiation from a source in lines of the main He I series in an expanding Universe is considered. A burst of radiation in continuum is assumed to occur at some instant of time corresponding to redshift z 0. This radiation is partially absorbed at different z < z 0 in lines of the main He I series (different pumping channels) and then is partially converted into radiation in subordinate lines. If ν ik is the laboratory transition frequency of some subordinate line emerging at some z, then at the present epoch its frequency will be ν = ν ik /(1 + z). The quantum yield, i.e., the number of photons emitted in the subordinate line per initial excited atom, has been calculated for different z (and, consequently, for different ν). Several pumping channels have been considered. We show that the luminescent lines can be both emission and absorption ones; the same line can be an emission one for one of the pumping channels and an absorption one for another. For example, the 1s2s-1s2p (1S-1P*) line is an emission one for the 1s2-1s2p pumping and an absorption one for the 1s2-1s3p pumping. We show that in the frequency range 30-80 GHz the total quantum yield for the first and second of the above channels can reach +50 and -50%, respectively.

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...

A 110 m long prototype helium transfer line for the HERA project

International Nuclear Information System (INIS)

Horvath, I.; Ming, P.; Von Burg, M.; Horlitz, G.; Sindt, H.

1986-01-01

A prototype helium transfer line of 110-m length was designed and constructed at SIN for the HERA project. This rendered a study of the assembly and handling processes as well as the determination of the heat losses into the transfer line. In this paper the transfer line structure is described and first results of heat transfer measurement for the specially developed super-insulation are presented

Caenorhabditis briggsae recombinant inbred line genotypes reveal inter-strain incompatibility and the evolution of recombination.

Directory of Open Access Journals (Sweden)

Joseph A Ross

2011-07-01

Full Text Available The nematode Caenorhabditis briggsae is an emerging model organism that allows evolutionary comparisons with C. elegans and exploration of its own unique biological attributes. To produce a high-resolution C. briggsae recombination map, recombinant inbred lines were generated from reciprocal crosses between two strains and genotyped at over 1,000 loci. A second set of recombinant inbred lines involving a third strain was also genotyped at lower resolution. The resulting recombination maps exhibit discrete domains of high and low recombination, as in C. elegans, indicating these are a general feature of Caenorhabditis species. The proportion of a chromosome's physical size occupied by the central, low-recombination domain is highly correlated between species. However, the C. briggsae intra-species comparison reveals striking variation in the distribution of recombination between domains. Hybrid lines made with the more divergent pair of strains also exhibit pervasive marker transmission ratio distortion, evidence of selection acting on hybrid genotypes. The strongest effect, on chromosome III, is explained by a developmental delay phenotype exhibited by some hybrid F2 animals. In addition, on chromosomes IV and V, cross direction-specific biases towards one parental genotype suggest the existence of cytonuclear epistatic interactions. These interactions are discussed in relation to surprising mitochondrial genome polymorphism in C. briggsae, evidence that the two strains diverged in allopatry, the potential for local adaptation, and the evolution of Dobzhansky-Muller incompatibilities. The genetic and genomic resources resulting from this work will support future efforts to understand inter-strain divergence as well as facilitate studies of gene function, natural variation, and the evolution of recombination in Caenorhabditis nematodes.

Lifetime and quenching of CO /a super 3 pi/ produced by recombination of CO2 ions in a helium afterglow.

Science.gov (United States)

Wauchop, T. S.; Broida, H. P.

1972-01-01

Demonstration that rapid dissociative recombination of CO2(+) in a flowing, helium afterglow is an efficient source of CO in the a super 3 pi metastable state. Ions produced by mixing CO2 with He(2 super 3 S) recombine to produce a CO metastable afterglow with a number density as great as 10 to the 9th per sq cm. Monitoring of the (a super 3 pi-X super 1 sigma) Cameron transition in CO was used to study the lifetime and quenching of CO (a super 3 pi) by CO2, N2, NO, and He. Recombination of CO2(+) also produces CO in the d super 3 delta and a' super 3 sigma states.

Line intensity ratios of helium atom in an ionizing plasma

International Nuclear Information System (INIS)

Sasaki, Satoshi; Goto, Motoshi; Kato, Takako; Takamura, Shuichi

1998-10-01

Effective emission rate coefficients C em eff (λ), line intensity ratios, C em eff (λ 1 )/C em eff (λ 2 ), and S eff /C em eff (λ), with S eff the ionization rate coefficient, are obtained by the collisional radiative model for an ionizing plasma using new excitation and ionization rate coefficients. In the plasma with electron density n e > 10 4 cm -3 , C em eff (λ) for various lines are enlarged, since the normalized population densities for the metastable states, n(2 1,3 S)/n He , becomes large, and the excitation rate coefficients from 2 1,3 S, C 21,3S→i , are large compared to that from the ground state C 11S→i . In high n e plasma (n e > 10 12 cm -3 ), with frequent electron impacts on the excited heliums, n(i)/n He become constant to n e , which results in the decrease of C em eff (λ). Hot electrons and resonance scattering, which are often important for the experimental applications, are included in this model. A small amount of hot electrons (several percents) can enhance the line emission and ionization rates for low electron temperature plasma with T e (T e 1 S - n 1 P) and enlarges n 1 P and 2 1 S populations when the column density of helium gas n He x L exceeds 2x10 13 [cm -2 ]. (author)

Measurements of the Spectral Light Emission from Decaying High Pressure Helium Plasmas

Energy Technology Data Exchange (ETDEWEB)

Stevefelt, J; Johansson, J

1971-04-15

The rate of electron density decay has been determined in a helium pulsed discharge plasma at pressures ranging from 100 to 600 Torr, primarily during the early afterglow where the electron density is from 1019 to 2 x 1017/m3. Measurements of the electrical conductivity and the absolute intensity of the light emission were made. The effective recombination rate coefficient was found to increase faster than linearly with gas pressure. The total photon emission rate was significantly lower than the effective recombination rate. Below 400 Torr pressure the afterglow was dominated by He-bands, which were related to the recombination of He{sub 2+} and He{sub 3+} ions. At higher pressures the appearance of intense lines originating from the atomic n = 3 and 23 P states is proposed to result from the He{sub 4+} recombination. Absorption measurements of the atomic metastable concentration gave evidence for recombination directly into the 23 S state. The concentration of molecular metastables was surprisingly low. The light emission had a Techi dependence, with 0 < chi < 0.35 for the intense atomic lines and 0.78 < chi < 1.10 for the molecular bands

Measurements of the Spectral Light Emission from Decaying High Pressure Helium Plasmas

International Nuclear Information System (INIS)

Stevefelt, J.; Johansson, J.

1971-04-01

The rate of electron density decay has been determined in a helium pulsed discharge plasma at pressures ranging from 100 to 600 Torr, primarily during the early afterglow where the electron density is from 10 19 to 2 x 10 17 /m 3 . Measurements of the electrical conductivity and the absolute intensity of the light emission were made. The effective recombination rate coefficient was found to increase faster than linearly with gas pressure. The total photon emission rate was significantly lower than the effective recombination rate. Below 400 Torr pressure the afterglow was dominated by He-bands, which were related to the recombination of He 2 + and He 3 + ions. At higher pressures the appearance of intense lines originating from the atomic n = 3 and 2 3 P states is proposed to result from the He 4 + recombination. Absorption measurements of the atomic metastable concentration gave evidence for recombination directly into the 2 3 S state. The concentration of molecular metastables was surprisingly low. The light emission had a T e χ dependence, with 0 < χ < 0.35 for the intense atomic lines and 0.78 < χ < 1.10 for the molecular bands

Calculation of the density shift and broadening of the transition lines in pionic helium: Computational problems

Energy Technology Data Exchange (ETDEWEB)

Bakalov, Dimitar, E-mail: dbakalov@inrne.bas.bg [Bulgarian Academy of Sciences, INRNE (Bulgaria)

2015-08-15

The potential energy surface and the computational codes, developed for the evaluation of the density shift and broadening of the spectral lines of laser-induced transitions from metastable states of antiprotonic helium, fail to produce convergent results in the case of pionic helium. We briefly analyze the encountered computational problems and outline possible solutions of the problems.

Radio recombination lines from H II regions

International Nuclear Information System (INIS)

Silverglate, P.R.

1978-01-01

Radio recombination lines have been observed from forty-six H II regions. The Arecibo 1000-foot radio telescope was used to provide high sensitivity and high angular resolution at 1400 MHz (gain approx. 7.7 0 K/Jy, HPBW = 3:2) and 2372 MHZ (gain approx. 6.3 0 K/Jy, HPBW = 2'). Observations were made at 1400 MHz in the frequency switching mode, and at 2372 MHz in the total power mode. Gaussians were fit to be observed lines to derive velocities, line widths, and line temperatures. From the velocities kinematic distances were derived. For eleven sources H I absorption measurements were also made. The absorption spectra enabled the kinematic distance ambiguity to be resolved for some sources. The absorption spectra themselves were found to have extremely sharp, non-gaussian edges. One explanation for these is a model where the interstellar medium contains many H I cloudlets with T/sub s/less than or equal to 100 0 K and turbulent velocities less than or equal to 3 km/s. The H I absorption spectrum is then a superposition of many narrow gaussian profiles. It was also found from a comparison of H I absorption velocities with radio recombination line velocities that peculiar motions exist in the interstellar medium with velocities of up to 10 km/s. Using the measured line temperatures and continuum temperatures, estimates were desired of emission measures, electron temperatures, and electron densities, using a non-LTE analysis. Non-LTE effects were important only for the hottest and densest H II regions. The non-LTE calculations were checked through a comparison derivation of electron temperatures using hydrogen beta lines

Molecular and Recombination Lines in the Central Region of Sagittarius B2

Science.gov (United States)

Curtis, J.; Langston, G.

2005-12-01

We present observations of recombination and molecular lines towards Sgr B2 in the frequency range 12.4 to 15.0 GHz. In this frequency range, Hα , β , and γ lines, Heα recombination lines and emission from the SO molecule are detected. Molecular absorption lines from OH, H2CO, and CH3CO are detected at velocity 62±3 km/s. Measurements of the line widths and intensities are presented for the central region of Sgr B2. We detect two previously un-reported molecular absorption lines at 12388.0 and 14625.8 MHz (v=0. in LSR Frame). For selected recombination and molecular lines, we present images of a 10x10 arc-minute region centered on Sgr B2(M). We discuss the sources of three H2CO absorption features detected at 62±3, 6±5, and 100±10 km/s. This was done as a summer REU project in 2005 at the National Radio Astronomy Observatory's Green Bank site, and was funded by the National Science Foundation's REU program.

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)

Determining the Pressure Shift of Helium I Lines Using White Dwarf Stars

Science.gov (United States)

Camarota, Lawrence

This dissertation explores the non-Doppler shifting of Helium lines in the high pressure conditions of a white dwarf photosphere. In particular, this dissertation seeks to mathematically quantify the shift in a way that is simple to reproduce and account for in future studies without requiring prior knowledge of the star's bulk properties (mass, radius, temperature, etc.). Two main methods will be used in this analysis. First, the spectral line will be quantified with a continuous wavelet transformation, and the components will be used in a chi2 minimizing linear regression to predict the shift. Second, the position of the lines will be calculated using a best-fit Levy-alpha line function. These techniques stand in contrast to traditional methods of quantifying the center of often broad spectral lines, which usually assume symmetry on the parts of the lines.

Recombinant protein production from stable mammalian cell lines and pools.

Science.gov (United States)

Hacker, David L; Balasubramanian, Sowmya

2016-06-01

We highlight recent developments for the production of recombinant proteins from suspension-adapted mammalian cell lines. We discuss the generation of stable cell lines using transposons and lentivirus vectors (non-targeted transgene integration) and site-specific recombinases (targeted transgene integration). Each of these methods results in the generation of cell lines with protein yields that are generally superior to those achievable through classical plasmid transfection that depends on the integration of the transfected DNA by non-homologous DNA end-joining. This is the main reason why these techniques can also be used for the generation of stable cell pools, heterogenous populations of recombinant cells generated by gene delivery and genetic selection without resorting to single cell cloning. This allows the time line from gene transfer to protein production to be reduced. Copyright © 2016 Elsevier Ltd. All rights reserved.

On-line methanol sensor system development for recombinant ...

African Journals Online (AJOL)

On-line methanol sensor system development for recombinant human serum ... of the methanol sensor system was done in a medium environment with yeast cells ... induction at a low temperature and a pH where protease does not function.

Electron temperature measurement by a helium line intensity ratio method in helicon plasmas

International Nuclear Information System (INIS)

Boivin, R.F.; Kline, J.L.; Scime, E.E.

2001-01-01

Electron temperature measurements in helicon plasmas are difficult. The presence of intense rf fields in the plasma complicates the interpretation of Langmuir probe measurements. Furthermore, the non-negligible ion temperature in the plasma considerably shortens the lifetime of conventional Langmuir probes. A spectroscopic technique based on the relative intensities of neutral helium lines is used to measure the electron temperature in the HELIX (Hot hELicon eXperiment) plasma [P. A. Keiter et al., Phys. Plasmas 4, 2741 (1997)]. This nonintrusive diagnostic is based on the fact that electron impact excitation rate coefficients for helium singlet and triplet states differ as a function of the electron temperature. The different aspects related to the validity of this technique to measure the electron temperature in rf generated plasmas are discussed in this paper. At low plasma density (n e ≤10 11 cm -3 ), this diagnostic is believed to be very reliable since the population of the emitting level can be easily estimated with reasonable accuracy by assuming that all excitation originates from the ground state (steady-state corona model). At higher density, secondary processes (excitation transfer, excitation from metastable, cascading) become more important and a more complex collisional radiative model must be used to predict the electron temperature. In this work, different helium transitions are examined and a suitable transition pair is identified. For an electron temperature of 10 eV, the line ratio is measured as a function of plasma density and compared to values predicted by models. The measured line ratio function is in good agreement with theory and the data suggest that the excitation transfer is the dominant secondary process in high-density plasmas

Evaluation of Drought Tolerance of Bread Wheat Recombinant Inbred Lines

Directory of Open Access Journals (Sweden)

N Zafar Naderi

2014-10-01

Full Text Available To evaluateresponse of bread wheat recombinant inbred lines to water deficit, a split plot experiment arranged in randomized complete block design (CRBD was conducted using eight recombinant inbred lines and their parental cultivars (Roshan and Super Head with three replications under three irrigation levels (80, 120 and 160 mm evaporation from class A pan at the Agriculture Research Station of Islamic Azad University, Tabriz Branch during 2009. The results of analysis of variance data collected revealed significant difference among lines and irrigation levels for grain yield. While line × irrigation level interaction was non significant for grain yield. Based on SSI and TOL, drought tolerance indices lines number 1, 7, 41 and Roshan cultivar under 120 mm evaporation, and lines number 7 and 19 under 160 mm evaporation were the tolerant lines. Under both stress conditions according to STI, MP and GMP indices, lines number 37, 38 and Roshan cultivar were recognized as the tolerant lines to water deficiet. Cluster analyses based on grain yield and drought tolerance indices recognized the lines number 1, 30, 32, 37, 38, 41 and Roshan cultivar under 120 mm and lines number 30, 37 and 38 and Roshan under 160 mm evaporation as the most drought tolerants and higher producers.

Anisotropic electron velocity distribution in an ECR helium plasma as determined from polarization of emission lines

International Nuclear Information System (INIS)

Iwamae, A; Sato, T; Horimoto, Y; Inoue, K; Fujimoto, T; Uchida, M; Maekawa, T

2005-01-01

A helium plasma is produced by electron-cyclotron resonance heating in a cusp-configuration magnetic field. Several neutral helium lines are found polarized in the direction perpendicular to the magnetic field; the maximum polarization degree exceeds 10%. The polarization degree and intensity of the emission lines yield, respectively, the alignment and population of the upper levels. The population-alignment collisional-radiative model is developed, and the experimental result is interpreted in terms of an anisotropic electron velocity distribution; it is of a Saturn-type with the central thermal component of 14 eV and the 'ring' component displaced by 9.2 eV from the central component. The relative number of 'ring' electrons is 40%. (letter to the editor)

Aperture synthesis observations of recombination lines from compact HII regions

International Nuclear Information System (INIS)

Gorkom, J.H. van.

1980-01-01

This thesis describes a continuation of early attempts to attain a high spectral dynamic range in general and to study recombination lines from compact HII regions in particular. These observations are made with the WSRT, until recently, the only instrument with sufficient angular resolution and sensitivity to provide at 6 cm detailed line maps of compact HII regions. An investigation into the spectral stability of the WSRT is described. Chromatic errors were found and their effects on maps are shown. These errors were found in the 80 channel filter spectrometer which was still in use at that time. The advent of the digital line backend (DLB) improved the dynamic range by an order of magnitude. An experiment is described which was partially aimed at testing the spectral stability of the DLB. It concerns a search for HI emission from the high velocity system of NGC 1275. Recombination line observations of the compact components in five giant HII regions are presented. The author discusses the radiative transfer problem in recombination lines and shows that non-LTE effects and pressure broadening can be of importance in compact HII regions. Observations obtained with the DLB are also presented. Because of the much better instrumental quality and improved insight into calibration procedures, mapping the H110α emission of DR21 and both the H110α and H166α emission of W3 was succeeded. (Auth.)

Determination of helium and oxygen abundances in gaseous nebulae

International Nuclear Information System (INIS)

Pronik, V.I.

1975-01-01

A new method of determining the abudance of helium and oxygen is proposed. It is based on the statement that functions of atomic distribution with states of ionization may be determined to the sufficient precision by the amount of atoms in two states of ionization. The abudance of helium atoms in nebulae is determined with most probability, since of three possible states of ionization two states with the overwhelming majority atoms may be directly observed. The amount of He++ ions is determined from He 2 recombination lines, and the amount of He+ ions is from He1 lines. The total abudance of He atoms can be found from the observed ratios of I(4686)/I(Hsub(β)) and I(4471)/I(Hsub(β)) at any degree of ionization. These ratios slightly depend on the electron temperature. For oxygen, unlike helium, the observed ratios depend on the electron temperature of gas, and at high densities they also depend on the density of electrons (it is necessary to take account of deactivation of the excited level by electron impacts). Constructed are curves of equal abundance He/H=const for determining He/H according to the ratios observed I(4686)/I(Hsub(β)) and I(4471)/I(Hsub(β)) and curves of equal abudance O/H=const for determining O/H according to the ratios observed I(3727)/I(Hsub(/b)) and I(Nsub(1)+Nsub(2))/I(Hsub(β)), corrected preliminarily for density and temperature

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

The origin of radio recombination lines seen toward supernova remnants

International Nuclear Information System (INIS)

Pankonin, V.; Downes, D.

1976-01-01

New observations have been made of the 166 α spectrum in the direction of the supernova remnants G-0.6 - 0.1, 3 C 391 and W 49 B. The variation of the intensity of the hydrogen recombination lines with frequency indicates that the lines arise in extended, low-density H II regions and not in cold clouds. (orig.) [de

Stark broadening of the 1640- and 4686-A lines of ionized helium

International Nuclear Information System (INIS)

Greene, R.L.

1976-01-01

The Stark-broadened profiles of the 1640- and 4686-A lines of ionized helium have been calculated using an approximation to the electron broadening operator in the unified classical-path theory of Smith, Vidal, and Cooper. The approximation is such that the results reproduce the time-ordered impact-theory results in the line center, and the ionized-radiator quasistatic results in the far wings. Sample calculations at n/sub e/ = 10/sup 17/ cm/sup -3/ and T = 40 000 degreeK are found to give significantly more narrow profiles than the corresponding modified-impact-theory results because of a different treatment of the lower-state interaction. Indirect comparison with experiment indicates that the calculated lines are too narrow, but it is expected that the inclusion of neglected effects of ion dynamics and inelastic collisions would improve agreement

Neutral helium spectral lines in dense plasmas

International Nuclear Information System (INIS)

Omar, Banaz; Wierling, August; Roepke, Gerd; Guenter, Sibylle

2006-01-01

Shift and broadening of isolated neutral helium lines 7281 A ring (2 1 P-3 1 S), 7065 A ring (2 3 P-3 3 S), 6678 A ring (2 1 P-3 1 D), 5048 A ring (2 1 P-4 1 S), 4922 A ring (2 1 P-4 1 D), and 4713 A ring (2 3 P-4 3 S) in a dense plasma are investigated. Based on a quantum statistical theory, the electronic contributions to the shift and width are considered, using the method of thermodynamic Green functions. Dynamic screening of the electron-atom interaction is included. Compared to the width, the electronic shift is more affected by dynamical screening. This effect increases at high density. A cut-off procedure for strong collisions is used. The contribution of the ions is taken into account in a quasi-static approximation, with both the quadratic Stark effect and the quadrupole interaction included. The results for shift and width agree well with the available experimental and theoretical data

Comparative pharmacology of a new recombinant FSH expressed by a human cell line

DEFF Research Database (Denmark)

Koechling, Wolfgang; Plaksin, Daniel; Croston, Glenn E.

2017-01-01

Recombinant FSH proteins are important therapeutic agents for the treatment of infertility, including follitropin alfa expressed in Chinese Hamster Ovary (CHO) cells and, more recently, follitropin delta expressed in the human cell line PER.C6. These recombinant FSH proteins have distinct glycosy...

DIRECT EVALUATION OF THE HELIUM ABUNDANCES IN OMEGA CENTAURI

Energy Technology Data Exchange (ETDEWEB)

Dupree, A. K.; Avrett, E. H., E-mail: dupree@cfa.harvard.edu, E-mail: eavrett@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

2013-08-20

A direct measure of the helium abundances from the near-infrared transition of He I at 1.08 {mu}m is obtained for two nearly identical red giant stars in the globular cluster Omega Centauri. One star exhibits the He I line; the line is weak or absent in the other star. Detailed non-local thermal equilibrium semi-empirical models including expansion in spherical geometry are developed to match the chromospheric H{alpha}, H{beta}, and Ca II K lines, in order to predict the helium profile and derive a helium abundance. The red giant spectra suggest a helium abundance of Y {<=} 0.22 (LEID 54064) and Y = 0.39-0.44 (LEID 54084) corresponding to a difference in the abundance {Delta}Y {>=} 0.17. Helium is enhanced in the giant star (LEID 54084) that also contains enhanced aluminum and magnesium. This direct evaluation of the helium abundances gives observational support to the theoretical conjecture that multiple populations harbor enhanced helium in addition to light elements that are products of high-temperature hydrogen burning. We demonstrate that the 1.08 {mu}m He I line can yield a helium abundance in cool stars when constraints on the semi-empirical chromospheric model are provided by other spectroscopic features.

Helium induced fine structure in the electronic spectra of anthracene derivatives doped into superfluid helium nanodroplets

International Nuclear Information System (INIS)

Pentlehner, D.; Slenczka, A.

2015-01-01

Electronic spectra of organic molecules doped into superfluid helium nanodroplets show characteristic features induced by the helium environment. Besides a solvent induced shift of the electronic transition frequency, in many cases, a spectral fine structure can be resolved for electronic and vibronic transitions which goes beyond the expected feature of a zero phonon line accompanied by a phonon wing as known from matrix isolation spectroscopy. The spectral shape of the zero phonon line and the helium induced phonon wing depends strongly on the dopant species. Phonon wings, for example, are reported ranging from single or multiple sharp transitions to broad (Δν > 100 cm −1 ) diffuse signals. Despite the large number of example spectra in the literature, a quantitative understanding of the helium induced fine structure of the zero phonon line and the phonon wing is missing. Our approach is a systematic investigation of related molecular compounds, which may help to shed light on this key feature of microsolvation in superfluid helium droplets. This paper is part of a comparative study of the helium induced fine structure observed in electronic spectra of anthracene derivatives with particular emphasis on a spectrally sharp multiplet splitting at the electronic origin. In addition to previously discussed species, 9-cyanoanthracene and 9-chloroanthracene will be presented in this study for the first time

Polysome profiling of mAb producing CHO cell lines links translational control of cell proliferation and recombinant mRNA loading onto ribosomes with global and recombinant protein synthesis.

Science.gov (United States)

Godfrey, Charlotte L; Mead, Emma J; Daramola, Olalekan; Dunn, Sarah; Hatton, Diane; Field, Ray; Pettman, Gary; Smales, C Mark

2017-08-01

mRNA translation is a key process determining growth, proliferation and duration of a Chinese hamster ovary (CHO) cell culture and influences recombinant protein synthesis rate. During bioprocessing, CHO cells can experience stresses leading to reprogramming of translation and decreased global protein synthesis. Here we apply polysome profiling to determine reprogramming and translational capabilities in host and recombinant monoclonal antibody-producing (mAb) CHO cell lines during batch culture. Recombinant cell lines with the fastest cell specific growth rates were those with the highest global translational efficiency. However, total ribosomal capacity, determined from polysome profiles, did not relate to the fastest growing or highest producing mAb cell line, suggesting it is the ability to utilise available machinery that determines protein synthetic capacity. Cell lines with higher cell specific productivities tended to have elevated recombinant heavy chain transcript copy numbers, localised to the translationally active heavy polysomes. The highest titre cell line was that which sustained recombinant protein synthesis and maintained high recombinant transcript copy numbers in polysomes. Investigation of specific endogenous transcripts revealed a number that maintained or reprogrammed into heavy polysomes, identifying targets for potential cell engineering or those with 5' untranslated regions that might be utilised to enhance recombinant transcript translation. © 2017 The Authors. Biotechnology Journal published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.)

Space and time resolved spectroscopy of laser-produced plasmas: A study of density-sensitive x-ray transitions in helium-like and neon-like ions

Energy Technology Data Exchange (ETDEWEB)

Young, Bruce Kai Fong

1988-09-01

The determination of level populations and detailed population mechanisms in dense plasmas has become an increasingly important problem in atomic physics. In this work, the density variation of line intensities and level populations in aluminum K-shell and molybdenum and silver L-shell emission spectra have been measured from high-powered, laser-produced plasmas. For each case, the density dependence of the observed line emission is due to the effect of high frequency electron-ion collisions on metastable levels. The density dependent line intensities vary greatly in laser-produced plasmas and can be used to extract detailed information concerning the population kinetics and level populations of the ions. The laser-plasmas had to be fully characterized in order to clearly compare the observed density dependence with atomic theory predictions. This has been achieved through the combined use of new diagnostic instruments and microdot targets which provided simultaneously space, time, and spectrally resolved data. The plasma temperatures were determined from the slope of the hydrogen-like recombination continuum. The time resolved electron density profiles were measured using multiple frame holographic interferometry. Thus, the density dependence of K-shell spectral lines could be clearly examined, independent of assumptions concerning the dynamics of the plasma. In aluminum, the electron density dependence of various helium-like line intensity ratios were measured. Standard collisional radiative equilibrium models fail to account for the observed density dependence measured for the ''He/sub ..cap alpha..//IC'' ratio. Instead, a quasi-steady state atomic model based on a purely recombining plasma is shown to accurately predict the measured density dependence. This same recombining plasma calculation successfully models the density dependence of the high-n ''He/sub ..gamma..//He/sub ..beta../'' and ''He/sub delta

Space and time resolved spectroscopy of laser-produced plasmas: A study of density-sensitive x-ray transitions in helium-like and neon-like ions

International Nuclear Information System (INIS)

Young, Bruce Kai Fong.

1988-09-01

The determination of level populations and detailed population mechanisms in dense plasmas has become an increasingly important problem in atomic physics. In this work, the density variation of line intensities and level populations in aluminum K-shell and molybdenum and silver L-shell emission spectra have been measured from high-powered, laser-produced plasmas. For each case, the density dependence of the observed line emission is due to the effect of high frequency electron-ion collisions on metastable levels. The density dependent line intensities vary greatly in laser-produced plasmas and can be used to extract detailed information concerning the population kinetics and level populations of the ions. The laser-plasmas had to be fully characterized in order to clearly compare the observed density dependence with atomic theory predictions. This has been achieved through the combined use of new diagnostic instruments and microdot targets which provided simultaneously space, time, and spectrally resolved data. The plasma temperatures were determined from the slope of the hydrogen-like recombination continuum. The time resolved electron density profiles were measured using multiple frame holographic interferometry. Thus, the density dependence of K-shell spectral lines could be clearly examined, independent of assumptions concerning the dynamics of the plasma. In aluminum, the electron density dependence of various helium-like line intensity ratios were measured. Standard collisional radiative equilibrium models fail to account for the observed density dependence measured for the ''He/sub α//IC'' ratio. Instead, a quasi-steady state atomic model based on a purely recombining plasma is shown to accurately predict the measured density dependence. This same recombining plasma calculation successfully models the density dependence of the high-n ''He/sub γ//He/sub β/'' and ''He/sub δ//He/sub β/'' helium-like resonance line intensity ratios

INTERSTELLAR METASTABLE HELIUM ABSORPTION AS A PROBE OF THE COSMIC-RAY IONIZATION RATE

International Nuclear Information System (INIS)

Indriolo, Nick; McCall, Benjamin J.; Hobbs, L. M.; Hinkle, K. H.

2009-01-01

The ionization rate of interstellar material by cosmic rays has been a major source of controversy, with different estimates varying by three orders of magnitude. Observational constraints of this rate have all depended on analyzing the chemistry of various molecules that are produced following cosmic-ray ionization, and in many cases these analyses contain significant uncertainties. Even in the simplest case (H + 3 ), the derived ionization rate depends on an (uncertain) estimate of the absorption path length. In this paper, we examine the feasibility of inferring the cosmic-ray ionization rate using the 10830 A absorption line of metastable helium. Observations through the diffuse clouds toward HD 183143 are presented, but yield only an upper limit on the metastable helium column density. A thorough investigation of He + chemistry reveals that only a small fraction of He + will recombine into the triplet state and populate the metastable level. In addition, excitation to the triplet manifold of helium by secondary electrons must be accounted for as it is the dominant mechanism which produces He* in some environments. Incorporating these various formation and destruction pathways, we derive new equations for the steady state abundance of metastable helium. Using these equations in concert with our observations, we find ζ He -15 s -1 , an upper limit about 5 times larger than the ionization rate previously inferred for this sight line using H + 3 . While observations of interstellar He* are extremely difficult at present, and the background chemistry is not nearly as simple as previously thought, potential future observations of metastable helium would provide an independent check on the cosmic-ray ionization rate derived from H + 3 in diffuse molecular clouds, and, perhaps more importantly, allow the first direct measurements of the ionization rate in diffuse atomic clouds.

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

Radio recombination lines from diffuse interstellar gas in the Galaxy

International Nuclear Information System (INIS)

Cersosimo, J.C.; Onello, J.S.

1991-01-01

The paper reports the detection of the H159-alpha and H200-beta radio recombination lines at 1.62 GHz at l = 30.5 deg and 31.0 deg in the Galactic plane. Using the new observations obtained with the NRAO 43 m telescope a non-LTE analysis is presented to show that the observed LTE intensity ratio for these lines can arise from an inhomogeneous ionized nebula with a low-density component. 16 refs

Helium pressures in RHIC vacuum cryostats and relief valve requirements from magnet cooling line failure

Energy Technology Data Exchange (ETDEWEB)

Liaw, C.J.; Than, Y.; Tuozzolo, J.

2011-03-28

A catastrophic failure of the RHIC magnet cooling lines, similar to the LHC superconducting bus failure incident, would pressurize the insulating vacuum in the magnet and transfer line cryostats. Insufficient relief valves on the cryostats could cause a structural failure. A SINDA/FLUINT{reg_sign} model, which simulated the 4.5K/4 atm helium flowing through the magnet cooling system distribution lines, then through a line break into the vacuum cryostat and discharging via the reliefs into the RHIC tunnel, had been developed to calculate the helium pressure inside the cryostat. Arc flash energy deposition and heat load from the ambient temperature cryostat surfaces were included in the simulations. Three typical areas: the sextant arc, the Triplet/DX/D0 magnets, and the injection area, had been analyzed. Existing relief valve sizes were reviewed to make sure that the maximum stresses, caused by the calculated maximum pressures inside the cryostats, did not exceed the allowable stresses, based on the ASME Code B31.3 and ANSYS results. The conclusions are as follows: (1) The S/F simulation results show that the highest internal pressure in the cryostats, due to the magnet line failure, is {approx}37 psig (255115 Pa); (2) Based on the simulation, the temperature on the cryostat chamber, INJ Q8-Q9, could drop to 228 K, which is lower than the material minimum design temperature allowed by the Code; (3) Based on the ASME Code and ANSYS results, the reliefs on all the cryostats inside the RHIC tunnel are adequate to protect the vacuum chambers when the magnet cooling lines fail; and (4) In addition to the pressure loading, the thermal deformations, due to the temperature decrease on the cryostat chambers, could also cause a high stress on the chamber, if not properly supported.

Helium pressures in RHIC vacuum cryostats and relief valve requirements from magnet cooling line failure

International Nuclear Information System (INIS)

Liaw, C.J.; Than, Y.; Tuozzolo, J.

2011-01-01

A catastrophic failure of the RHIC magnet cooling lines, similar to the LHC superconducting bus failure incident, would pressurize the insulating vacuum in the magnet and transfer line cryostats. Insufficient relief valves on the cryostats could cause a structural failure. A SINDA/FLUINT(reg s ign) model, which simulated the 4.5K/4 atm helium flowing through the magnet cooling system distribution lines, then through a line break into the vacuum cryostat and discharging via the reliefs into the RHIC tunnel, had been developed to calculate the helium pressure inside the cryostat. Arc flash energy deposition and heat load from the ambient temperature cryostat surfaces were included in the simulations. Three typical areas: the sextant arc, the Triplet/DX/D0 magnets, and the injection area, had been analyzed. Existing relief valve sizes were reviewed to make sure that the maximum stresses, caused by the calculated maximum pressures inside the cryostats, did not exceed the allowable stresses, based on the ASME Code B31.3 and ANSYS results. The conclusions are as follows: (1) The S/F simulation results show that the highest internal pressure in the cryostats, due to the magnet line failure, is ∼37 psig (255115 Pa); (2) Based on the simulation, the temperature on the cryostat chamber, INJ Q8-Q9, could drop to 228 K, which is lower than the material minimum design temperature allowed by the Code; (3) Based on the ASME Code and ANSYS results, the reliefs on all the cryostats inside the RHIC tunnel are adequate to protect the vacuum chambers when the magnet cooling lines fail; and (4) In addition to the pressure loading, the thermal deformations, due to the temperature decrease on the cryostat chambers, could also cause a high stress on the chamber, if not properly supported.

Binary and ternary recombination of D3+ ions with electrons in He-D2 plasma

International Nuclear Information System (INIS)

Glosik, J.; Korolov, I.; Plasil, R.; Kotrik, T.; Dohnal, P.; Novotny, O.; Varju, J.; Roucka, S.; Greene, Chris H.; Kokoouline, V.

2009-01-01

An experimental study is reported about the recombination of D 3 + ions with electrons in a low-temperature plasma (200-300 K) consisting of He with a small admixture of D 2 . At several temperatures, the pressure dependence of the apparent binary recombination rate coefficient (α eff ) was measured over a broad range of helium pressures (200-2000 Pa). The binary and ternary recombination rate coefficients were obtained from measured pressure dependences of α eff . The binary recombination rate coefficient obtained α bin (300 K)=(2.7±0.9)x10 -8 cm 3 s -1 is in agreement with recent theory. The ternary recombination rate coefficient obtained is K He (300 K)=(1.8±0.6)x10 -25 cm 6 s -1 . In analogy with the recently described process of helium-assisted ternary recombination of H 3 + ions, it is suggested that the ternary helium-assisted recombination of D 3 + ions proceeds through the formation of a neutral long-lived highly excited Rydberg molecule D 3 followed by a collision with a He atom.

Binary and ternary recombination of D3+ ions with electrons in He-D2 plasma

Science.gov (United States)

Glosík, J.; Korolov, I.; Plašil, R.; Kotrík, T.; Dohnal, P.; Novotný, O.; Varju, J.; Roučka, Š.; Greene, Chris H.; Kokoouline, V.

2009-10-01

An experimental study is reported about the recombination of D3+ ions with electrons in a low-temperature plasma (200-300 K) consisting of He with a small admixture of D2 . At several temperatures, the pressure dependence of the apparent binary recombination rate coefficient (αeff) was measured over a broad range of helium pressures (200-2000 Pa). The binary and ternary recombination rate coefficients were obtained from measured pressure dependences of αeff . The binary recombination rate coefficient obtained αbin(300K)=(2.7±0.9)×10-8cm3s-1 is in agreement with recent theory. The ternary recombination rate coefficient obtained is KHe(300K)=(1.8±0.6)×10-25cm6s-1 . In analogy with the recently described process of helium-assisted ternary recombination of H3+ ions, it is suggested that the ternary helium-assisted recombination of D3+ ions proceeds through the formation of a neutral long-lived highly excited Rydberg molecule D3 followed by a collision with a He atom.

Screening of recombinant inbred lines for salinity tolerance in bread ...

African Journals Online (AJOL)

Screening a large number of plants for salinity tolerance is not easy, therefore this investigation was performed to evaluate and screen 186 F8 recombinant inbred lines (RILs) derived from a cross between Superhead#2 (Super Seri) and Roshan wheat varieties for salinity tolerance. All the individuals were evaluated under ...

Time-dependent analysis of visible helium line-ratios for electron temperature and density diagnostic using synthetic simulations on NSTX-U

Energy Technology Data Exchange (ETDEWEB)

Muñoz Burgos, J. M., E-mail: jmunozbu@pppl.gov; Stutman, D.; Tritz, K. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Barbui, T.; Schmitz, O. [Department of Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

2016-11-15

Helium line-ratios for electron temperature (T{sub e}) and density (n{sub e}) plasma diagnostic in the Scrape-Off-Layer (SOL) and edge regions of tokamaks are widely used. Due to their intensities and proximity of wavelengths, the singlet, 667.8 and 728.1 nm, and triplet, 706.5 nm, visible lines have been typically preferred. Time-dependency of the triplet line (706.5 nm) has been previously analyzed in detail by including transient effects on line-ratios during gas-puff diagnostic applications. In this work, several line-ratio combinations within each of the two spin systems are analyzed with the purpose of eliminating transient effects to extend the application of this powerful diagnostic to high temporal resolution characterization of plasmas. The analysis is done using synthetic emission modeling and diagnostic for low electron density NSTX SOL plasma conditions by several visible lines. Quasi-static equilibrium and time-dependent models are employed to evaluate transient effects of the atomic population levels that may affect the derived electron temperatures and densities as the helium gas-puff penetrates the plasma. The analysis of a wider range of spectral lines will help to extend this powerful diagnostic to experiments where the wavelength range of the measured spectra may be constrained either by limitations of the spectrometer or by other conflicting lines from different ions.

HIGH-n HYDROGEN RECOMBINATION LINES FROM THE FIRST GALAXIES

International Nuclear Information System (INIS)

Rule, E.; Loeb, A.; Strelnitski, V. S.

2013-01-01

We investigate the prospects of blind and targeted searches in the radio domain (10 MHz to 1 THz) for high-n hydrogen recombination lines from the first generation of galaxies, at z ∼ 4 km s –1 , allow us to assess the blind search time necessary for detection by a given facility. We show that the chances for detection are the highest in the millimeter and submillimeter domains, but finding spontaneous emission in a blind search, especially from redshifts z >> 1, is a challenge even with powerful facilities, such as the Actama Large Millimeter/Submillimeter Array and Square Kilometre Array. The probability of success is higher for a targeted search of lines with principal quantum number n ∼ 10 in Lyman-break galaxies amplified by gravitational lensing. Detection of more than one hydrogen line in such a galaxy will allow for line identification and a precise determination of the galaxy's redshift

The 21-cm Signal from the cosmological epoch of recombination

Energy Technology Data Exchange (ETDEWEB)

Fialkov, A. [Departement de Physique, Ecole Normale Superieure, CNRS, 24 rue Lhomond, Paris, 75005 (France); Loeb, A., E-mail: anastasia.fialkov@phys.ens.fr, E-mail: aloeb@cfa.harvard.edu [Department of Astronomy, Harvard University, 60 Garden Street, MS-51, Cambridge, MA, 02138 (United States)

2013-11-01

The redshifted 21-cm emission by neutral hydrogen offers a unique tool for mapping structure formation in the early universe in three dimensions. Here we provide the first detailed calculation of the 21-cm emission signal during and after the epoch of hydrogen recombination in the redshift range of z ∼ 500–1,100, corresponding to observed wavelengths of 100–230 meters. The 21-cm line deviates from thermal equilibrium with the cosmic microwave background (CMB) due to the excess Lyα radiation from hydrogen and helium recombinations. The resulting 21-cm signal reaches a brightness temperature of a milli-Kelvin, orders of magnitude larger than previously estimated. Its detection by a future lunar or space-based observatory could improve dramatically the statistical constraints on the cosmological initial conditions compared to existing two-dimensional maps of the CMB anisotropies.

The 21-cm Signal from the cosmological epoch of recombination

International Nuclear Information System (INIS)

Fialkov, A.; Loeb, A.

2013-01-01

The redshifted 21-cm emission by neutral hydrogen offers a unique tool for mapping structure formation in the early universe in three dimensions. Here we provide the first detailed calculation of the 21-cm emission signal during and after the epoch of hydrogen recombination in the redshift range of z ∼ 500–1,100, corresponding to observed wavelengths of 100–230 meters. The 21-cm line deviates from thermal equilibrium with the cosmic microwave background (CMB) due to the excess Lyα radiation from hydrogen and helium recombinations. The resulting 21-cm signal reaches a brightness temperature of a milli-Kelvin, orders of magnitude larger than previously estimated. Its detection by a future lunar or space-based observatory could improve dramatically the statistical constraints on the cosmological initial conditions compared to existing two-dimensional maps of the CMB anisotropies

The deduction of low-Z ion temperature and densities in the JET tokamak using charge exchange recombination spectroscopy

International Nuclear Information System (INIS)

Boileau, A.; Hellermann, M. von; Horton, L.D.; Spence, J.; Summers, H.P.

1989-01-01

A charge exchange recombination spectroscopy (CXRS) diagnostic has been established on JET to study fully stripped low-Z species. Ion temperature in the plasma centre is measured from visible lines of helium, carbon and oxygen excited by charge exchange with heating neutral beam particles. Coincident cold components produced at the plasma edge are apparent on helium and carbon spectra and most spectra are subject to accidental blending from other species' edge plasma emission. The charge exchange feature can be isolated from the various composite lines and all three impurities agree on the same temperature within experimental error. Observed column emissivities are converted into absolute impurity densities using a neutral beam attenuation code and charge exchange effective rate coefficients. Comprehensive new calculations have been performed to obtain the effective rate coefficients. The models take detailed account of cascading and the influence of the plasma environment in causing l-mixing, and allow the n-dependence of the rate coefficients to be addressed experimentally. The effective ion charge reconstructed from simultaneous measurements of the densities of dominant impurities shows good agreement with the value inferred from visible Bremsstrahlung. Some illustrative results are shown for helium (helium discharge or minority r.f.. heating), carbon and oxygen concentrations monitored during characteristic operating regimes. (author)

Electron temperature measurements in lowdensity plasmas by helium spectroscopy

International Nuclear Information System (INIS)

Brenning, N.

1977-09-01

This method to use relative intensities of singlet and triplet lines of neutral helium to measure electron temperature in low-density plasmas is examined. Calculations from measured and theoretical data about transitions in neutral helium are carried out and compared to experimental results. It is found that relative intensities of singlet and triplet lines from neutral helium only can be used for TE determination in low-density, short-duration plasmas. The most important limiting processes are excitation from the metastable 2 3 S level and excitation transfer in collisions between electrons and excited helium atoms. An evaluation method is suggested, which minimizes the effect of these processes. (author)

The Decay of Optically Thick Helium Plasmas, Taking into Account Ionizing Collisions between Metastable Atoms or Molecules

International Nuclear Information System (INIS)

Stevefelt, J.

1970-11-01

The effective recombination rate of a helium afterglow plasma, which is optically thick towards the resonance lines, is calculated from the coupled rate equations for the number densities of free electrons and of metastable atoms or molecules. The model employed is a neutral plasma, consisting of one kind of ions and one kind of metastables. The ions are lost by electron-ion recombination only, with subsequent formation of metastables, which are then deactivated in collisions with free electrons or with other metastables: in the latter case one electron is regained to the free state. When the rate constants for these various processes are time-independent, it is found that after a certain transition time a transient equilibrium between the number densities of electrons and metastables is attained. In a dense afterglow plasma, where the recombination coefficient may be large, the transient equilibrium density of metastables may become significantly higher than the qua si-equilibrium value obtained by equating the time derivative of the metastable density to zero, and the effective recombination coefficient may be reduced by much more than a factor of two

The Decay of Optically Thick Helium Plasmas, Taking into Account Ionizing Collisions between Metastable Atoms or Molecules

Energy Technology Data Exchange (ETDEWEB)

Stevefelt, J

1970-11-15

The effective recombination rate of a helium afterglow plasma, which is optically thick towards the resonance lines, is calculated from the coupled rate equations for the number densities of free electrons and of metastable atoms or molecules. The model employed is a neutral plasma, consisting of one kind of ions and one kind of metastables. The ions are lost by electron-ion recombination only, with subsequent formation of metastables, which are then deactivated in collisions with free electrons or with other metastables: in the latter case one electron is regained to the free state. When the rate constants for these various processes are time-independent, it is found that after a certain transition time a transient equilibrium between the number densities of electrons and metastables is attained. In a dense afterglow plasma, where the recombination coefficient may be large, the transient equilibrium density of metastables may become significantly higher than the qua si-equilibrium value obtained by equating the time derivative of the metastable density to zero, and the effective recombination coefficient may be reduced by much more than a factor of two

Recombination activating activity of XRCC1 analogous genes in X-ray sensitive and resistant CHO cell lines

International Nuclear Information System (INIS)

Golubnitchaya-Labudova, O.; Hoefer, M.; Portele, A.; Vacata, V.; Rink, H.; Lubec, G.

1997-01-01

The XRCC1 gene (X-ray repair cross complementing) complements the DNA repair deficiency of the radiation sensitive Chinese hamster ovary (CHO) mutant cell line EM9 but the mechanism of the correction is not elucidated yet. XRCC1 shows substantial homology to the RAG2 gene (recombination activating gene) and we therefore tried to answer the question, whether structural similarities (sequence of a putative recombination activating domain, aa 332-362 for XRCC1 and aa 286-316 in RAG2) would reflect similar functions of the homologous, putative recombination activating domain. PCR experiments revealed that no sequence homologous to the structural part of human XRCC1 was present in cDNA of CHO. Differential display demonstrated two putative recombination activating in the parental CHO line AA8 and one in the radiosensitive mutant EM9. Southern blot experiments showed the presence of several genes with partial homology to human XRCC1. Recombination studies consisted of expressing amplified target domains within chimeric proteins in recA - bacteria and subsequent detection of recombination events by sequencing the recombinant plasmids. Recombination experiments demonstrated recombination activating activity of all putative recombination activating domains amplified from AA8 and EM9 genomes as reflected by deletions within the inserts of the recombinant plasmids. The recombination activating activity of XRCC1 analogues could explain a mechanism responsible for the correction of the DNA repair defect in EM9. (author)

Why is observable radio recombination line emission from galactic HII regions always close to LTE

International Nuclear Information System (INIS)

Shaver, P.A.

1980-01-01

There is no evidence for significant deviations from LTE in single-dish observations of radio recombination line emission from galactic HII regions. This is in agreement with the known properties of HII regions, particularly their density variations and limited range of excitation parameters; the optimum configuration for strong observable non-LTE effects, low electron density and high emission measure, simply does not exist in galactic HII regions, and the observed lines are emitted under near-LTE conditions. Models of the Orion Nebulae and NGC 6604 are presented which fit all available data and show only weak stimulated emission. It is concluded that reliable electron temperatures can indeed be obtained from straightforward analysis of appropriate radio recombination lines. (orig.)

Dielectronic recombination and resonant transfer excitation processes for helium-like krypton

Institute of Scientific and Technical Information of China (English)

Hu Xiao-Li; Qu Yi-Zhi; Zhang Song-Bin; Zhang Yu

2012-01-01

The relativistic configuration interaction method is employed to calculate the dielectronic recombination (DR) cross sections of helium-like krypton via the 1s21nl' (n =2,3,...,15) resonances.Then,the resonant transfer excitation (RTE) processes of Kr34+ colliding with H,He,H2,and CHx (x =0-4) targets are investigated under the impulse approximation.The needed Compton profiles of targets are obtained from the Hartree-Fock wave functions.The RTE cross sections are strongly dependent on DR resonant energies and strengths,and the electron momentum distributions of the target.For H2 and H targets,the ratio of their RTE cross sections changes from 1.85 for the 1s2121' to 1.88 for other resonances,which demonstrates the weak molecular effects on the Compton profiles of H2.For CHx (x =0-4) targets,the main contribution to the RTE cross section comes from the carbon atom since carbon carries 6 electrons;as the number of hydrogen increases in CHx,the RTE cross section almost increases by the same value,displaying the strong separate atom character for the hydrogen.However,further comparison of the individual orbital contributions of C(2p,2s,ls) and CH4(1t2,2a1,1a1) to the RTE cross sections shows that the molecular effects induce differences of about 25.1％,19.9％,and 0.2％ between 2p-1t2,2s-2a1,and 1s-1a1 orbitals,respectively.

Transfer line from the PSB to the PS (recombination)

CERN Multimedia

CERN PhotoLab

1976-01-01

After sequential ejection of 5 bunches from each of the 4 rings of the Booster (originally 800 MeV, now 1.4 GeV), the 4 batches are brought to the same vertical level, so as to form a string of 20 bunches, filling the circumference of the PS. This vertical "recombination" is performed in the transfer line, using vertical bending magnets, septa and kickers. Here we see the section where the beam from ring 4 (the top one) is brought down to the level of ring 3, and the beam from ring 1 up to the level of ring 2. Further downstream (to the right, outside this picture), level 2 is brought up to level 3, identical to that of the PS. After this original recombination scheme, other ways of combining the 4 beams, vertically and/or longitudinally, were developed and used in operation.

Measurement of OH density and air-helium mixture ratio in an atmospheric-pressure helium plasma jet

International Nuclear Information System (INIS)

Yonemori, Seiya; Ono, Ryo; Nakagawa, Yusuke; Oda, Tetsuji

2012-01-01

The absolute density of OH radicals in an atmospheric-pressure helium plasma jet is measured using laser-induced fluorescence (LIF). The plasma jet is generated in room air by applying a pulsed high voltage onto a quartz tube with helium gas flow. The time-averaged OH density is 0.10 ppm near the quartz tube nozzle, decreasing away from the nozzle. OH radicals are produced from water vapour in the helium flow, which is humidified by water adsorbed on the inner surface of the helium line and the quartz tube. When helium is artificially humidified using a water bubbler, the OH density increases with humidity and reaches 2.5 ppm when the water vapour content is 200 ppm. Two-dimensional distribution of air-helium mixture ratio in the plasma jet is also measured using the decay rate of the LIF signal waveform which is determined by the quenching rate of laser-excited OH radicals. (paper)

Structure and dynamics of molecular complex He2*(a3Σu+) in condensed phases of helium

International Nuclear Information System (INIS)

Kafanov, S.G.; Parshin, A.Ya.; Tadoshchenko, I.A.

2000-01-01

The absorption spectra of the helium triplet metastable molecules in the a 3 Σ u + states in the liquid 4 He and 3 He by various pressures and in the 3 He dense gas are studied. The analysis of the spectrum, corresponding to the a 3 Σ u + → c 3 Σ g + transition, proves the conclusion on the availability of a microscopic bubble, surrounding the molecule in the liquid helium. Simple approximation of the wave function of the molecule valent electron is proposed and the bubble parameters under various experimental conditions are determined. The coefficient conditions are determined. The coefficient of the molecular recombination in the liquid 3 He and 4 He by different pressures and in the 3 He cold gas is experimentally determined. The obtained results agree well with the mutual recombination theory. It is shown, that molecular polarization in the helium condensed phases under the magnetic field effect does not lead to their mutual recombination [ru

Registration of Wyandot × PI 567301B soybean recombinant inbred line population

Science.gov (United States)

A soybean [Glycine max (L.) Merr] mapping population (Reg. No., SNL MAP) consisting of 357 F7-derived recombinant inbred lines (RILs) was jointly developed by the USDA-Agricultural Research Service and the Ohio Agricultural Research and Development Center (OARDC) in Wooster, OH. The population was ...

Advances in the helium-jet coupled on-line mass seperator RAMA

International Nuclear Information System (INIS)

Moltz, D.M.; Aeystoe, J.; Cable, M.D.; Parry, R.F.; Haustein, P.E.; Wouters, J.M.; Cerny, J.; California Univ., Berkeley

1981-01-01

General improvements to the on-line mass separator RAMA have yielded a greater reliability and efficiency for some elements. A new utilitarian helium-jet chamber has been installed to facilitate quick target and degrader foil changes in addition to a new ion source holder. A higher efficiency hollow-cathode, cathode-extraction ion source for lower melting point elements ( 0 C) has also been designed. Tests with the beta-delayed proton emitter 37 Ca showed a factor of five increase in yield over the old hollow-cathode, anode-extraction source. A differentially-pumped tape drive system compatible with both γ-γ and β-γ experiments has been incorporated into the general detection system. All major operating parameters will soon be monitored by a complete stand-alone microprocessor system which will eventually be upgraded to a closed-loop control system. (orig.)

Advances in the helium-jet coupled on-line mass separator RAMA

International Nuclear Information System (INIS)

Moltz, D.M.; Aysto, J.; Cable, M.D.; Parry, R.F.; Haustein, P.E.; Wouters, J.M.; Cerny, J.

1980-01-01

General improvements to the on-line mass separator RAMA (Recoil Atom Mass Analyzer) have yielded a greater reliability and efficiency for some elements. A new utilitarian helium-jet chamber has been installed to facilitate quick target and degrader foil changes in addition to a new ion source holder. A higher efficiency hollow-cathode, cathode-extraction ion source, for lower melting point elements ( 0 C) has also been designed. Tests with the beta-delayed proton emitter 37 Ca showed a factor of five increase in yield over the old hollow-cathode, anode-extraction source. A differentially-pumped-tape drive system compatible with both γ-γ and β-γ experiments has been incorporated into the general detection system. All major operating parameters will soon be monitored by a complete stand-alone microprocessor system which will eventually be upgraded to a closed-loop control system

Calculated L-shell x-ray line intensities for proton and helium ion impact

International Nuclear Information System (INIS)

Cohen, D.D.; Harrigan, M.

1986-01-01

Theoretical L-shell X-ray line intensities have been calculated for proton and helium bombardment of atoms from nickel (Z 2 = 28) to curium (Z 2 = 96). The ionization cross sections for the three L subshells were obtained from the recent calculations by Cohen and Harrigan in the ECPSSR theory, which uses the plane-wave Born approximation (PWBA) with corrections for energy loss (E), Coulomb deflection (C), perturbed-stationary-state (PSS), and relativistic (R) effects. The fluorescence yields and Coster-Kronig transition probabilities were taken from M. O. Krause (Phys. Chem. Ref. Data 8, 307 (1979)) and the L-subshell emission rates from S. I. Salem, S. L. Panosian, and R. A. Krause (Atomic Data and Nuclear Data Tables 14, 91 (1974)). The line intensities Ll, Lα, Leta, Lβ 1 to Lβ 6 , Lβ/sub 9,10/, and Lγ 1 to Lgg 6 are tabulated for selected ion energies from 0.2 to 10 MeV

Effects of chemical and physical agents on recombination events in cells of the germ line of male and female Drosophila melanogaster.

Science.gov (United States)

Würgler, F E

1991-01-01

Genotoxic agents can induce mutations as well as recombination in the genetic material. The fruit fly Drosophila melanogaster was one of the first assay systems to test physical and chemical agents for recombinogenic effects. Such effects can be observed in cells of the germ line as well as in somatic cells. At present information is available on 54 agents, among them 48 chemicals that have been tested in cells of the germ line of males and/or females. Effects on meiotic recombination in female germ cells cannot simply be classified as positive or negative since for a number of agents, depending on the chromosome region studied, recombination frequencies may be increased, unaffected or decreased. The male germ line of D. melanogaster represents a unique situation because meiotic recombination does not occur. Among 25 agents tested in male germ cells 24 did induce male recombination, among them alkylating, intercalating and cross-linking agents, direct-acting ones as well as compounds needing metabolic activation. With several compounds the frequency of induced recombination is highest in the heterochromatic regions near the centromeres. In brood pattern analyses, e.g., after exposure of adult males to ionizing radiation, the first appearance of crossover progeny is indicative of the sampling of exposed spermatocytes. In premeiotic cells of the male and the female germ line mitotic recombination can occur. Upon clonal expansion of the recombinant cells, clusters of identical crossovers can be observed.

Spectral survey of helium lines in a linear plasma device for use in HELIOS imaging

Science.gov (United States)

Ray, H. B.; Biewer, T. M.; Fehling, D. T.; Isler, R. C.; Unterberg, E. A.

2016-11-01

Fast visible cameras and a filterscope are used to examine the visible light emission from Oak Ridge National Laboratory's Proto-MPEX. The filterscope has been configured to perform helium line ratio measurements using emission lines at 667.9, 728.1, and 706.5 nm. The measured lines should be mathematically inverted and the ratios compared to a collisional radiative model (CRM) to determine Te and ne. Increasing the number of measurement chords through the plasma improves the inversion calculation and subsequent Te and ne localization. For the filterscope, one spatial chord measurement requires three photomultiplier tubes (PMTs) connected to pellicle beam splitters. Multiple, fast visible cameras with narrowband filters are an alternate technique for performing these measurements with superior spatial resolution. Each camera contains millions of pixels; each pixel is analogous to one filterscope PMT. The data can then be inverted and the ratios compared to the CRM to determine 2-dimensional "images" of Te and ne in the plasma. An assessment is made in this paper of the candidate He I emission lines for an imaging technique.

Signals from the epoch of cosmological recombination (Karl Schwarzschild Award Lecture 2008)

Science.gov (United States)

Sunyaev, R. A.; Chluba, J.

2009-07-01

The physical ingredients to describe the epoch of cosmological recombination are amazingly simple and well-understood. This fact allows us to take into account a very large variety of physical processes, still finding potentially measurable consequences for the energy spectrum and temperature anisotropies of the Cosmic Microwave Background (CMB). In this contribution we provide a short historical overview in connection with the cosmological recombination epoch and its connection to the CMB. Also we highlight some of the detailed physics that were studied over the past few years in the context of the cosmological recombination of hydrogen and helium. The impact of these considerations is two-fold: The associated release of photons during this epoch leads to interesting and unique deviations of the Cosmic Microwave Background (CMB) energy spectrum from a perfect blackbody, which, in particular at decimeter wavelength and the Wien part of the CMB spectrum, may become observable in the near future. Despite the fact that the abundance of helium is rather small, it still contributes a sizeable amount of photons to the full recombination spectrum, leading to additional distinct spectral features. Observing the spectral distortions from the epochs of hydrogen and helium recombination, in principle would provide an additional way to determine some of the key parameters of the Universe (e.g. the specific entropy, the CMB monopole temperature and the pre-stellar abundance of helium). Also it permits us to confront our detailed understanding of the recombination process with direct observational evidence. In this contribution we illustrate how the theoretical spectral template of the cosmological recombination spectrum may be utilized for this purpose. We also show that because hydrogen and helium recombine at very different epochs it is possible to address questions related to the thermal history of our Universe. In particular the cosmological recombination radiation may

Recombinant lines for less-spininess in steroid-bearing Solanum viarum using induced mutants as parents

International Nuclear Information System (INIS)

Krishnan, R.; Nanda Kumar, D.; Subhas Chander, M.

1988-01-01

In the domestication of the wild, spinous and steroid-bearing Solanum viarum (syn. S. khasianum var. chatterjeeanum) induced mutations play a major role. The development of Glaxo and BARC mutants catalysed commercial cultivation of this species for its berries containing solasodine, used in steroid industries. The commercially more popular Glaxo mutant population consists predominantly of plants that are totally free of spines in aerial parts except lamina where few straight spines develop. The BARC mutant still possesses spines on aerial parts including the persistent calyx. However, the laminary spines of the BARC mutant are curved and vestigial. Comparative studies on morphology, growth behaviour and agronomic characters of the two mutants, their wild progenitor and their hybrid progenies showed that the three types differ only for spine character. In F 2 generation of a cross involving the Glaxo and BARC mutants, a double mutant recombinant was recovered. The recombinant is devoid of spines in aerial parts like its Glaxo mutant parent, but possesses laminary curved vestigial spines like the BARC parent. The spine characters of the recombinant are inherited double recessive. Three advanced lines of this recombinant type (IIHR 2n - 1,2 and 3) were tested in replicated trials 1985 and 1986. They showed parity in berry yield and solasodine content with the Glaxo mutant and three promising lines evolved elsewhere viz. 'RRL (Bhuhaneswar) Y-14', 'RRL (Jorhat)' and 'Pusa'. The results indicate gainful use of induced mutants in hybridization leading to development of superior less-spiny lines of steroid bearing Solanum viarum

Displacements and intensities of the components of hydrogenic lines of the helium atom in the presence of exterior uniform electrical and magnetic fields

International Nuclear Information System (INIS)

Deutsch, C.; Herman, L.; Nguyen, H.; Drawin, H.W.

1967-01-01

The Waller-Foster method for hydrogenic lines of neutral helium is extended in order to take into account an external magnetic field (vector K) having an arbitrary angle with an external constant electric field (vector F). The diagonal correction has been evaluated numerically taking into account recent experimental data. A Fortran IV program written for the CDC 3600 computer allows to calculate the displacements and the intensities for any hydrogenic transition. Special attention is given to the {2-4} transitions in neutral helium. (authors) [fr

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.

4He abundances: Optical versus radio recombination line measurements

Science.gov (United States)

Balser, Dana S.; Rood, Robert T.; Bania, T. M.

2010-04-01

Accurate measurements of the 4He/H abundance ratio are important in constraining Big Bang nucleosynthesis, models of stellar and Galactic evolution, and H ii region physics. We discuss observations of radio recombination lines using the Green Bank Telescope toward a small sample of H ii regions and planetary nebulae. We report 4He/H abundance ratio differences as high as 15-20% between optical and ratio data that are difficult to reconcile. Using the H ii regions S206 and M17 we determine 4He production in the Galaxy to be dY/dZ = 1.71 ± 0.86.

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

Radiolysis study of actinide complexing agent by irradiation with helium ion beam

International Nuclear Information System (INIS)

Sugo, Yumi; Taguchi, Mitsumasa; Sasaki, Yuji; Hirota, Koichi; Kimura, Takaumi

2009-01-01

α-Radiolysis of N,N,N',N'-tetraoctyldiglycolamide (TODGA) in n-dodecane was investigated by the irradiation with helium ion beam provided by a tandem accelerator. The radiation chemical yield for the degradation of TODGA by helium ion beam irradiation was less than that by γ-rays irradiation. It is considered that the radical cations of n-dodecane, which contribute to the charge transfer reaction with the TODGA molecules, decrease by recombination in track by high LET radiations such as α-particles.

Spectral survey of helium lines in a linear plasma device for use in HELIOS imaging

Energy Technology Data Exchange (ETDEWEB)

Ray, H. B., E-mail: rayhb@ornl.gov [University of Tennessee, Knoxville, Tennessee 37996 (United States); Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Biewer, T. M.; Fehling, D. T.; Isler, R. C.; Unterberg, E. A. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2016-11-15

Fast visible cameras and a filterscope are used to examine the visible light emission from Oak Ridge National Laboratory’s Proto-MPEX. The filterscope has been configured to perform helium line ratio measurements using emission lines at 667.9, 728.1, and 706.5 nm. The measured lines should be mathematically inverted and the ratios compared to a collisional radiative model (CRM) to determine T{sub e} and n{sub e}. Increasing the number of measurement chords through the plasma improves the inversion calculation and subsequent T{sub e} and n{sub e} localization. For the filterscope, one spatial chord measurement requires three photomultiplier tubes (PMTs) connected to pellicle beam splitters. Multiple, fast visible cameras with narrowband filters are an alternate technique for performing these measurements with superior spatial resolution. Each camera contains millions of pixels; each pixel is analogous to one filterscope PMT. The data can then be inverted and the ratios compared to the CRM to determine 2-dimensional “images” of T{sub e} and n{sub e} in the plasma. An assessment is made in this paper of the candidate He I emission lines for an imaging technique.

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)

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

Temperature dependence of binary and ternary recombination of H3+ ions with electrons

International Nuclear Information System (INIS)

Glosik, J.; Plasil, R.; Korolov, I.; Kotrik, T.; Novotny, O.; Hlavenka, P.; Dohnal, P.; Varju, J.; Kokoouline, V.; Greene, Chris H.

2009-01-01

We study binary and the recently discovered process of ternary He-assisted recombination of H 3 + ions with electrons in a low-temperature afterglow plasma. The experiments are carried out over a broad range of pressures and temperatures of an afterglow plasma in a helium buffer gas. Binary and He-assisted ternary recombination are observed and the corresponding recombination rate coefficients are extracted for temperatures from 77 to 330 K. We describe the observed ternary recombination as a two-step mechanism: first, a rotationally excited long-lived neutral molecule H 3 * is formed in electron-H 3 + collisions. Second, the H 3 * molecule collides with a helium atom that leads to the formation of a very long-lived Rydberg state with high orbital momentum. We present calculations of the lifetimes of H 3 * and of the ternary recombination rate coefficients for para- and ortho-H 3 + . The calculations show a large difference between the ternary recombination rate coefficients of ortho- and para-H 3 + at temperatures below 300 K. The measured binary and ternary rate coefficients are in reasonable agreement with the calculated values.

Temperature dependence of binary and ternary recombination of H3+ ions with electrons

Science.gov (United States)

Glosík, J.; Plašil, R.; Korolov, I.; Kotrík, T.; Novotný, O.; Hlavenka, P.; Dohnal, P.; Varju, J.; Kokoouline, V.; Greene, Chris H.

2009-05-01

We study binary and the recently discovered process of ternary He-assisted recombination of H3+ ions with electrons in a low-temperature afterglow plasma. The experiments are carried out over a broad range of pressures and temperatures of an afterglow plasma in a helium buffer gas. Binary and He-assisted ternary recombination are observed and the corresponding recombination rate coefficients are extracted for temperatures from 77 to 330 K. We describe the observed ternary recombination as a two-step mechanism: first, a rotationally excited long-lived neutral molecule H3∗ is formed in electron- H3+ collisions. Second, the H3∗ molecule collides with a helium atom that leads to the formation of a very long-lived Rydberg state with high orbital momentum. We present calculations of the lifetimes of H3∗ and of the ternary recombination rate coefficients for para- and ortho- H3+ . The calculations show a large difference between the ternary recombination rate coefficients of ortho- and para- H3+ at temperatures below 300 K. The measured binary and ternary rate coefficients are in reasonable agreement with the calculated values.

QTL analysis of seed dormancy in Arabidopsis using recombinant inbred lines and MQM mapping

NARCIS (Netherlands)

Schaar, Wybe van der; Alonso-Blanco, Carlos; Léon-Kloosterziel, Karen M.; Jansen, Ritsert C.; Ooijen, Johan W. van; Koornneef, Maarten

1997-01-01

The genetic differences for seed germination between two commonly used Arabidopsis thaliana ecotypes Ler and Col, both showing a low level of seed dormancy, were investigated. The analysis was performed with 98 recombinant inbred lines (RILs) derived from the cross between the two ecotypes, and

Genetic Analysis of Recombinant Inbred Lines for Sorghum bicolor ? Sorghum propinquum

OpenAIRE

Kong, Wenqian; Jin, Huizhe; Franks, Cleve D.; Kim, Changsoo; Bandopadhyay, Rajib; Rana, Mukesh K.; Auckland, Susan A.; Goff, Valorie H.; Rainville, Lisa K.; Burow, Gloria B.; Woodfin, Charles; Burke, John J.; Paterson, Andrew H.

2013-01-01

We describe a recombinant inbred line (RIL) population of 161 F5 genotypes for the widest euploid cross that can be made to cultivated sorghum (Sorghum bicolor) using conventional techniques, S. bicolor ? Sorghum propinquum, that segregates for many traits related to plant architecture, growth and development, reproduction, and life history. The genetic map of the S. bicolor ? S. propinquum RILs contains 141 loci on 10 linkage groups collectively spanning 773.1 cM. Although the genetic map ha...

Study of a microwave discharge in argon/helium mixtures

International Nuclear Information System (INIS)

Saada, Serge

1983-01-01

A discharge created by a surface wave in Argon-Helium mixture is studied. First, the helium influence on plasma parameters has been studied (electron density, electric field, effective collision frequency, etc...), then, on excitation processes in the discharge. Relations between plasma lines, electron density and electric field have been established. [fr

Low-frequency Carbon Radio Recombination Lines. I. Calculations of Departure Coefficients

Energy Technology Data Exchange (ETDEWEB)

Salgado, F.; Morabito, L. K.; Oonk, J. B. R.; Salas, P.; Toribio, M. C.; Röttgering, H. J. A.; Tielens, A. G. G. M. [Leiden Observatory, University of Leiden, P.O. Box 9513, 2300 RA Leiden (Netherlands)

2017-03-10

In the first paper of this series, we study the level population problem of recombining carbon ions. We focus our study on high quantum numbers, anticipating observations of carbon radio recombination lines to be carried out by the Low Frequency Array. We solve the level population equation including angular momentum levels with updated collision rates up to high principal quantum numbers. We derive departure coefficients by solving the level population equation in the hydrogenic approximation and including low-temperature dielectronic capture effects. Our results in the hydrogenic approximation agree well with those of previous works. When comparing our results including dielectronic capture, we find differences that we ascribe to updates in the atomic physics (e.g., collision rates) and to the approximate solution method of the statistical equilibrium equations adopted in previous studies. A comparison with observations is discussed in an accompanying article, as radiative transfer effects need to be considered.

Biological insights into the expression of translation initiation factors from recombinant CHOK1SV cell lines and their relationship to enhanced productivity.

Science.gov (United States)

Mead, Emma J; Masterton, Rosalyn J; Feary, Marc; Obrezanova, Olga; Zhang, Lin; Young, Robert; Smales, C Mark

2015-12-15

Translation initiation is on the critical pathway for the production of monoclonal antibodies (mAbs) by mammalian cells. Formation of a closed loop structure comprised of mRNA, a number of eukaryotic initiation factors (eIFs) and ribosomal proteins has been proposed to aid re-initiation of translation and therefore increase global translational efficiency. We have determined mRNA and protein levels of the key components of the closed loop, eIFs (eIF3a, eIF3b, eIF3c, eIF3h, eIF3i and eIF4G1), poly(A)-binding protein (PABP) 1 and PABP-interacting protein 1 (PAIP1), across a panel of 30 recombinant mAb-producing GS-CHOK1SV cell lines with a broad range of growth characteristics and production levels of a model recombinant mAb. We have used a multi-level statistical approach to investigate the relationship between key performance indicators (cell growth and recombinant antibody productivity) and the intracellular amounts of target translation initiation factor proteins and the mRNAs encoding them. We show that high-producing cell lines maintain amounts of the translation initiation factors involved in the formation of the closed loop mRNA, maintaining these proteins at appropriate levels to deliver enhanced recombinant protein production. We then utilize knowledge of the amounts of these factors to build predictive models for and use cluster analysis to identify, high-producing cell lines. The present study therefore defines the translation initiation factor amounts that are associated with highly productive recombinant GS-CHOK1SV cell lines that may be targets for screening highly productive cell lines or to engineer new host cell lines with the potential for enhanced recombinant antibody productivity. © 2015 Authors; published by Portland Press Limited.

On the dynamic response of pressure transmission lines in the research of helium-charged free piston Stirling engines

Science.gov (United States)

Miller, Eric L.; Dudenhoefer, James E.

1989-01-01

The signal distortion inherent to pressure transmission lines in free-piston Stirling engine research is discussed. Based on results from classical analysis, guidelines are formulated to describe the dynamic response properties of a volume-terminated transmission tube for applications involving the helium-charged free-piston Stirling engines. The underdamped flow regime is described, the primary resonance frequency is derived, and the pressure phase and amplitude distortion are discussed. The scope and limitation of the dynamic response analysis are considered.

Plasma polarization spectroscopy on the ECR helium plasma in a cusp magnetic field

International Nuclear Information System (INIS)

Sato, T.; Iwamae, A.; Fujimoto, T.; Uchida, M.; Maekawa, T.

2004-01-01

Helium emission lines have been observed on the ECR plasma in a cusp field with the polarized components resolved. The polarization map is constructed for the 501.6 nm (2 1 S-3 1 P) line emission. Lines from n 1 P and n 1 D levels are strongly polarized and those from n 3 D levels are weakly polarized. As the helium pressure increases the polarization degree decreases. (author)

Helium bubbles aggravated defects production in self-irradiated copper

Science.gov (United States)

Wu, FengChao; Zhu, YinBo; Wu, Qiang; Li, XinZhu; Wang, Pei; Wu, HengAn

2017-12-01

Under the environment of high radiation, materials used in fission and fusion reactors will internally accumulate numerous lattice defects and bubbles. With extensive studies focused on bubble resolution under irradiation, the mutually effects between helium bubbles and displacement cascades in irradiated materials remain unaddressed. Therefore, the defects production and microstructure evolution under self-irradiation events in vicinity of helium bubbles are investigated by preforming large scale molecular dynamics simulations in single-crystal copper. When subjected to displacement cascades, distinguished bubble resolution categories dependent on bubble size are observed. With the existence of bubbles, radiation damage is aggravated with the increasing bubble size, represented as the promotion of point defects and dislocations. The atomic mechanisms of heterogeneous dislocation structures are attributed to different helium-vacancy cluster modes, transforming from the resolved gas trapped with vacancies to the biased absorption of vacancies by the over-pressured bubble. In both cases, helium impedes the recombination of point defects, leading to the accelerated formation of interstitial loops. The results and insight obtained here might contribute to understand the underlying mechanism of transmutant solute on the long-term evolution of irradiated materials.

An efficient continuous flow helium cooling unit for Moessbauer experiments

International Nuclear Information System (INIS)

Herbert, I.R.; Campbell, S.J.

1976-01-01

A Moessbauer continuous flow cooling unit for use with liquid helium over the temperature range 4.2 to 300K is described. The cooling unit can be used for either absorber or source studies in the horizontal plane and it is positioned directly on top of a helium storage vessel. The helium transfer line forms an integral part of the cooling unit and feeds directly into the storage vessel so that helium losses are kept to the minimum. The helium consumption is 0.12 l h -1 at 4.2 K decreasing to 0.055 l h -1 at 40 K. The unit is top loading and the exchange gas cooled samples can be changed easily and quickly. (author)

Comment on theories for helium-assisted void nucleation

International Nuclear Information System (INIS)

Russell, K.C.

1976-01-01

Voids form by agglomeration of irradiation-induced vacancies which remain after preferential absorption of self interstitials at dislocation lines. Helium which is formed by (n,α) transmutations and, in simulation studies, may be ion-implanted, often plays an important, but puzzling role. In some materials, very few voids form in the absence of helium, even after intense irradiation. In many other materials , voids form readily under a variety of irradiation conditions, even in the absence of helium. Why some materials require helium - typically in the 10 -6 apa (atom per atom) range - and others do not, and the reason for that particular level are by no means clear. The physics of void nucleation, particularly the role of helium, have been the subject of several theoretical papers. This note presents a critique of these theories, and then briefly outlines a new analysis which is not subject to their limitations. (Auth.)

Genetic Analysis of Health-Related Secondary Metabolites in a Brassica rapa Recombinant Inbred Line Population

NARCIS (Netherlands)

Bagheri, H.; Soda, El M.; Kim, H.K.; Fritsche, S.; Jung, C.; Aarts, M.G.M.

2013-01-01

The genetic basis of the wide variation for nutritional traits in Brassica rapa is largely unknown. A new Recombinant Inbred Line (RIL) population was profiled using High Performance Liquid Chromatography (HPLC) and Nuclear Magnetic Resonance (NMR) analysis to detect quantitative trait loci (QTLs)

Advances in Mammalian Cell Line Development Technologies for Recombinant Protein Production

Directory of Open Access Journals (Sweden)

Say Kong Ng

2013-04-01

Full Text Available From 2006 to 2011, an average of 15 novel recombinant protein therapeutics have been approved by US Food and Drug Administration (FDA annually. In addition, the expiration of blockbuster biologics has also spurred the emergence of biosimilars. The increasing numbers of innovator biologic products and biosimilars have thus fuelled the demand of production cell lines with high productivity. Currently, mammalian cell line development technologies used by most biopharmaceutical companies are based on either the methotrexate (MTX amplification technology or the glutamine synthetase (GS system. With both systems, the cell clones obtained are highly heterogeneous, as a result of random genome integration by the gene of interest and the gene amplification process. Consequently, large numbers of cell clones have to be screened to identify rare stable high producer cell clones. As such, the cell line development process typically requires 6 to 12 months and is a time, capital and labour intensive process. This article reviews established advances in protein expression and clone screening which are the core technologies in mammalian cell line development. Advancements in these component technologies are vital to improve the speed and efficiency of generating robust and highly productive cell line for large scale production of protein therapeutics.

Murine leukemia virus-derived retroviral vector has differential integration patterns in human cell lines used to produce recombinant factor VIII

Directory of Open Access Journals (Sweden)

Marcela Cristina Correa de Freitas

2014-06-01

Full Text Available OBJECTIVE: Nowadays recombinant factor VIII is produced in murine cells including in Chinese hamster ovary (CHO and baby hamster kidney cells (BHK. Previous studies, using the murine leukemia virus-derived retroviral vector pMFG-FVIII-P140K, modified two recombinant human cell lines, HepG2 and Hek293 to produce recombinant factor VIII. In order to characterize these cells, the present study aimed to analyze the integration pattern of retroviral vector pMFG-FVIII-P140K.METHODS: This study used ligation-mediated polymerase chain reaction to locate the site of viral vector integration by sequencing polymerase chain reaction products. The sequences were compared to genomic databases to characterize respective clones.RESULTS: The retroviral vector presented different and non-random profiles of integration between cells lines. A preference of integration for chromosomes 19, 17 and 11 was observed for HepG2FVIIIdB/P140K and chromosome 9 for Hek293FVIIIdB/P140K. In genomic regions such as CpG islands and transcription factor binding sites, there was no difference in the integration profiles for both cell lines. Integration in intronic regions of encoding protein genes (RefSeq genes was also observed in both cell lines. Twenty percent of integrations occurred at fragile sites in the genome of the HepG2 cell line and 17% in Hek293.CONCLUSION: The results suggest that the cell type can affect the profile of chromosomal integration of the retroviral vector used; these differences may interfere in the level of expression of recombinant proteins.

Flow visualization in superfluid helium-4 using He2 molecular tracers

Science.gov (United States)

Guo, Wei

Flow visualization in superfluid helium is challenging, yet crucial for attaining a detailed understanding of quantum turbulence. Two problems have impeded progress: finding and introducing suitable tracers that are small yet visible; and unambiguous interpretation of the tracer motion. We show that metastable He2 triplet molecules are outstanding tracers compared with other particles used in helium. These molecular tracers have small size and relatively simple behavior in superfluid helium: they follow the normal fluid motion at above 1 K and will bind to quantized vortex lines below about 0.6 K. A laser-induced fluorescence technique has been developed for imaging the He2 tracers. We will present our recent experimental work on studying the normal-fluid motion by tracking thin lines of He2 tracers created via femtosecond laser-field ionization in helium. We will also discuss a newly launched experiment on visualizing vortex lines in a magnetically levitated superfluid helium drop by imaging the He2 tracers trapped on the vortex cores. This experiment will enable unprecedented insight into the behavior of a rotating superfluid drop and will untangle several key issues in quantum turbulence research. We acknowledge the support from the National Science Foundation under Grant No. DMR-1507386 and the US Department of Energy under Grant No. DE-FG02 96ER40952.

Survey of atomic data base needs and accuracies for helium beam stopping and alpha particle diagnostics for ITER

International Nuclear Information System (INIS)

Summers, H.P.; Hellermann, M. von.

1992-01-01

This report is concerned with establishing a recommended collection of atomic collision data for the modelling, experimental investigation and exploitation of helium beams. The motivation stems from proposals for diagnostic beams for the ITER tokamak, targeted at alpha particle measurement via double charge transfer, neutralized alpha particle analysis and spectroscopic analysis of recombination radiation. The report discusses the beam energies, species involved in collisions with the helium atom beam (fuel, helium ash and plasma impurities) and plasma conditions prevailing in large tokamak devices. It also lists the required cross-section data

Effective selection criteria for screening drought tolerant recombinant inbred lines of sunflower

Directory of Open Access Journals (Sweden)

Abdi Nishtman

2013-01-01

Full Text Available In this study, seventy two sunflower recombinant inbred lines were tested for their yielding ability under both water-stressed and well-watered states. The inbred lines were evaluated in a rectangular 8´9 lattice design with two replications in both well-watered and water-stressed conditions, separately. Eight drought tolerance indices including stability tolerance index (STI, mean productivity (MP, geometric mean productivity (GMP, harmonic mean (HM, stress susceptibility index (SSI, tolerance index (TOL, yield index (YI and yield stability index (YSI were calculated based on grain yield for every genotype. Results showed the highest values of mean productivity (MP index, geometric mean productivity (GMP, yield index (YI, harmonic mean (HM and stress tolerance index (STI indices for ‘C134a’ inbred line and least values of stress susceptibility index (SSI and tolerance (TOL for C61 inbred line. According to correlation of indices with yield performance under both drought stress and non-stress states and principle component analysis, indices including HM, MP, GMP and STI could properly distinguish drought tolerant sunflower inbred lines with high yield performance under both states. Cluster analysis of inbred lines using Ys, Yp and eight indices, categorized them into four groups including 19, 6, 26 and 19 inbred lines.

Helium emission in the middle chromosphere

International Nuclear Information System (INIS)

Livshits, M.A.

1976-01-01

Slitless spectrograms obtained during the eclipse of 10 June 1972 have been analyzed to determine the height distribution of the D 3 He line intensity. For undisturbed regions the maximum of D 3 line intensity is confirmed to exist at about 1700 km above the limb. Besides the above mentioned maximum, in plages a considerable intensity may be observed at low heights (h 1000 km has been carried out within the low temperature mechanism of triplet helium emission taking into account the helium ionization by XUV radiation. The density dependence of the 2 3 S level population at different XUV flux values has been calculated. The observations give Nsub(e) approximately 2x10 10 cm -3 in the chromosphere at h = 2000 km. The probable coincidence of the H and He emission small filaments in the middle chromosphere is discussed. (Auth.)

Closely related glycosylation patterns of recombinant human IL-2 expressed in a CHO cell line and natural IL-2

International Nuclear Information System (INIS)

Vita, N.; Magazin, M.; Marchese, E.; Lupker, J.; Ferrara, P.

1990-01-01

We report here the study of the glycosylation pattern of human recombinant (r) IL2 expressed in a Chinese hamster ovary (CHO) cell line. The human rIL2 secreted by this high-producing recombinant CHO cell line was metabolically radiolabelled with [35S]-methionine, or with [3H]-glucosamine and [3H]-galactose, purified to homogeneity, and then characterized. The electrophoretic analysis of the [35S]-methionine-labelled proteins present in the culture medium of the CHO cell line showed that the rIL2 represents approximately 12% of the total secreted proteins. Furthermore, pulse-chase experiments showed that the glycosylated rIL2 is synthesized and secreted within 30 min. The point of attachment and the structure of the carbohydrate moiety of the rIL2 was determined by: amino-terminal sequencing and fingerprint analysis of the 3H-labelled rIL2, mass spectroscopy of the amino-terminal tryptic octapeptide, and carbohydrate analysis after enzymatic (Vibrio cholerae neuraminidase and Aspergillus oryzae beta-galactosidase) or sulfuric acid hydrolysis. The results indicate that the recombinant protein possesses a sugar moiety O-linked to the threonine residue at position 3 of the polypeptide chain, and that sialic acid, galactose and N-acetyl galactosamine are components of this carbohydrate moiety. Taken together these results suggest that the recombinant molecule is identical to natural IL2

Collisional broadening of alkali doublets by helium perturbers

Energy Technology Data Exchange (ETDEWEB)

Mullamphy, D F T [School of Mathematics, Physics and Information Technology, James Cook University, Townsville 4811 (Australia); Peach, G [Department of Physics and Astronomy, University College London WC1E 6BT (United Kingdom); Venturi, V [School of Mathematics, Physics and Information Technology, James Cook University, Townsville 4811 (Australia); Whittingham, I B [School of Mathematics, Physics and Information Technology, James Cook University, Townsville 4811 (Australia); Gibson, S J [School of Mathematics, Physics and Information Technology, James Cook University, Townsville 4811 (Australia)

2007-03-28

We report results for the Lorentzian profiles of the Li I, Na I and K I doublets and the Na I subordinate doublet broadened by helium perturbers for temperatures up to 3000 K. They have been obtained from a fully quantum-mechanical close-coupling description of the colliding atoms, the Baranger theory of line shapes and new ab initio potentials for the alkali-helium interaction. For all lines except the 769.9 nm K I line, the temperature dependence of the widths over the range 70 {<=} T {<=} 3000 K is accurately represented by the power law form w = aT{sup bb} with 0.38 < b < 0.43. The 769.9 nm K I line has this form for 500 {<=} T {<=} 3000 K with b having the higher value of 0.49. Although the shifts have a more complex temperature dependence, they all have the general feature of increasing with temperature above T {approx} 500 K apart from the 769.9 K I line whose shift decreases with temperature.

A high-yielding, generic fed-batch process for recombinant antibody production of GS-engineered cell lines

DEFF Research Database (Denmark)

Fan, Li; Zhao, Liang; Sun, Yating

2009-01-01

An animal component-free and chemically defined fed-batch process for GS-engineered cell lines producing recombinant antibodies has been developed. The fed-batch process relied on supplying sufficient nutrients to match their consumption, simultaneously minimizing the accumulation of byproducts....... This generic and high-yielding fed-batch process would shorten development time, and ensure process stability, thereby facilitating the manufacture of therapeutic antibodies by GS-engineered cell lines....

High resolution spectroscopy of six new extreme helium stars

Science.gov (United States)

Heber, U.; Jones, G.; Drilling, J. S.

1986-01-01

High resolution spectra of six newly discovered extreme helium stars are presented. LSS 5121 is shown to be a spectroscopical twin of the hot extreme helium star HD 160641. A preliminary LTE analysis of LSS 3184 yielded an effective temperature of 22,000 K and a surface gravity of log g = 3.2. Four stars form a new subgroup, classified by sharp-lined He I spectra and pronounced O II spectra, and it is conjectured that these lie close to the Eddington limit. The whole group of extreme helium stars apparently is inhomogeneous with respect to luminosity to mass ratio and chemical composition.

Genetic analysis of recombinant inbred lines for Sorghum bicolor × Sorghum propinquum.

Science.gov (United States)

Kong, Wenqian; Jin, Huizhe; Franks, Cleve D; Kim, Changsoo; Bandopadhyay, Rajib; Rana, Mukesh K; Auckland, Susan A; Goff, Valorie H; Rainville, Lisa K; Burow, Gloria B; Woodfin, Charles; Burke, John J; Paterson, Andrew H

2013-01-01

We describe a recombinant inbred line (RIL) population of 161 F5 genotypes for the widest euploid cross that can be made to cultivated sorghum (Sorghum bicolor) using conventional techniques, S. bicolor × Sorghum propinquum, that segregates for many traits related to plant architecture, growth and development, reproduction, and life history. The genetic map of the S. bicolor × S. propinquum RILs contains 141 loci on 10 linkage groups collectively spanning 773.1 cM. Although the genetic map has DNA marker density well-suited to quantitative trait loci mapping and samples most of the genome, our previous observations that sorghum pericentromeric heterochromatin is recalcitrant to recombination is highlighted by the finding that the vast majority of recombination in sorghum is concentrated in small regions of euchromatin that are distal to most chromosomes. The advancement of the RIL population in an environment to which the S. bicolor parent was well adapted (indeed bred for) but the S. propinquum parent was not largely eliminated an allele for short-day flowering that confounded many other traits, for example, permitting us to map new quantitative trait loci for flowering that previously eluded detection. Additional recombination that has accrued in the development of this RIL population also may have improved resolution of apices of heterozygote excess, accounting for their greater abundance in the F5 than the F2 generation. The S. bicolor × S. propinquum RIL population offers advantages over early-generation populations that will shed new light on genetic, environmental, and physiological/biochemical factors that regulate plant growth and development.

ON THE APPARENT NARROWING OF RADIO RECOMBINATION LINES AT HIGH PRINCIPAL QUANTUM NUMBERS

International Nuclear Information System (INIS)

Alexander, J.; Gulyaev, S.

2012-01-01

We critically analyze the Bell et al. findings on 'anomalous' widths of high-order hydrogen radio recombination lines in the Orion Nebula at 6 GHz. We review their method of modified frequency switching and show that the way this method is used for large Δn is not optimal and can lead to misinterpretation of measured spectral line parameters. Using a model of the Orion Nebula, conventional broadening theory, and Monte Carlo simulation, we determine a transition zone n = 224, ..., 241 (Δn = 11, ..., 14), where measurement errors grow quickly with n and become comparable with the measurement values themselves. When system noise and spectrum channelization are accounted for, our simulation predicts 'processed' line narrowing in the transition zone similar to that reported by Bell et al. We find good agreement between our simulation results and their findings, both in line temperatures and widths. We conclude, therefore, that Bell et al.'s findings do not indicate a need to revise Stark broadening theory.

Low-Frequency Carbon Recombination Lines in the Orion Molecular Cloud Complex

Science.gov (United States)

Tremblay, Chenoa D.; Jordan, Christopher H.; Cunningham, Maria; Jones, Paul A.; Hurley-Walker, Natasha

2018-05-01

We detail tentative detections of low-frequency carbon radio recombination lines from within the Orion molecular cloud complex observed at 99-129 MHz. These tentative detections include one alpha transition and one beta transition over three locations and are located within the diffuse regions of dust observed in the infrared at 100 μm, the Hα emission detected in the optical, and the synchrotron radiation observed in the radio. With these observations, we are able to study the radiation mechanism transition from collisionally pumped to radiatively pumped within the H ii regions within the Orion molecular cloud complex.

Evaluation of Spring Wheat Recombinant Inbred Lines under Drought Stress

Directory of Open Access Journals (Sweden)

M. Moghaddaszadeh-Ahrabi

2012-07-01

Full Text Available Iran is one of arid and semi-arid regions of the world. Wheat as a strategic agricultural products faces water deficiency in most areas of the country. Therefore, identification of the resistant varieties to drought stress is one of main aims for breeders. To assess effect of drought stress at heading on 72 spring wheat recombinant inbred lines derived from American Yecora Rojo (high yielder, dwarf and early maturity as paternal parent and Iranian No. 49 line (tall and late maturiting as maternal parent cross were studied. The experiment was conducted at the Research Station of the University of Tabriz using a randomized complete block design with two replications during 2009 growing season. Based on the results from combined analysis of variance significant difference was observed among lines for all of traits studied, except for harvest index, grain number per spike and days to heading. There was significant difference between normal and drought stress conditions. Since the interaction between line and conditions was insignificant for all traits, it does therefore, provide the possibility of comparing the lines without regard to irrigation levels. Based on the means of, the traits it was found that the lines 96, 122, 123 and 155 were superior. MP, GMP and STI indices were recognized to be suitable indices to identify superior lines. With respect to these indices, lines 96, 122, 123, 138, 149 and 155 were found superior as compared with remaining lines. Based on stepwise regression analysis of grain yield with other traits, respectively grain number per spike, number of spikes/m2 and 1000 kernel weight were inserted into final model as effective variables on grain yield, which made 81/9 percent of the grain yield variation. Path analysis of grain yield and related traits, based on stepwise regression, demonstrated the significant positive direct effect for grain number per spike, number of spikes/m2 and 1000 kernel weight on grain yield

Binary and ternary recombination of [image omitted] and [image omitted] ions with electrons in low temperature plasma

Science.gov (United States)

Glosík, J.; Plašil, R.; Kotrík, T.; Dohnal, P.; Varju, J.; Hejduk, M.; Korolov, I.; Roučka, Š.; Kokoouline, V.

2010-09-01

Measurements of recombination rate coefficients of binary and ternary recombination of ? and ? ions with electrons in a low temperature plasma are described. The experiments were carried out in the afterglow plasma in helium with a small admixture of Ar and parent gas (H2 or D2). For both ions a linear increase of measured apparent binary recombination rate coefficients (αeff) with increasing helium density was observed: αeff = αBIN + K He[He]. From the measured dependencies, we have obtained for both ions the binary (αBIN) and the ternary (K He) rate coefficients and their temperature dependence. For the description of observed ternary recombination a mechanism with two subsequent rate determining steps is proposed. In the first step, in ? + e- (or ? + e-) collision, a rotationally excited long-lived Rydberg molecule ? (or ? ) is formed. In the following step ? (or ? ) collides with a He atom of the buffer gas and this collision prevents autoionization of ? (or ? ). Lifetimes of the formed ? (or ? ) and corresponding ternary recombination rate coefficients have been calculated. The theoretical and measured binary and ternary recombination rate coefficients obtained for ? and ? ions are in good agreement.

The HI/OH/Recombination line survey of the inner Milky Way (THOR). Survey overview and data release 1

Science.gov (United States)

Beuther, H.; Bihr, S.; Rugel, M.; Johnston, K.; Wang, Y.; Walter, F.; Brunthaler, A.; Walsh, A. J.; Ott, J.; Stil, J.; Henning, Th.; Schierhuber, T.; Kainulainen, J.; Heyer, M.; Goldsmith, P. F.; Anderson, L. D.; Longmore, S. N.; Klessen, R. S.; Glover, S. C. O.; Urquhart, J. S.; Plume, R.; Ragan, S. E.; Schneider, N.; McClure-Griffiths, N. M.; Menten, K. M.; Smith, R.; Roy, N.; Shanahan, R.; Nguyen-Luong, Q.; Bigiel, F.

2016-10-01

Context. The past decade has witnessed a large number of Galactic plane surveys at angular resolutions below 20''. However, no comparable high-resolution survey exists at long radio wavelengths around 21 cm in line and continuum emission. Aims: We remedy this situation by studying the northern Galactic plane at 20'' resolution in emission of atomic, molecular, and ionized gas. Methods: Employing the Karl G. Jansky Very Large Array (VLA) in the C-array configuration and a large program, we observe the HI 21 cm line, four OH lines, nineteen Hnα radio recombination lines as well as the continuum emission from 1 to 2 GHz in full polarization over a large part of the first Galactic quadrant. Results: Covering Galactic longitudes from 14.5 to 67.4 deg and latitudes between ± 1.25 deg, we image all of these lines and the continuum at 20'' resolution. These data allow us to study the various components of the interstellar medium (ISM): from the atomic phase, traced by the HI line, to the molecular phase, observed by the OH transitions, to the ionized medium, revealed by the cm continuum and the Hnα radio recombination lines. Furthermore, the polarized continuum emission enables magnetic field studies. In this overview paper, we discuss the survey outline and present the first data release as well as early results from the different datasets. We now release the first half of the survey; the second half will follow later after the ongoing data processing has been completed. The data in fits format (continuum images and line data cubes) can be accessed through the project web-page. Conclusions: The HI/OH/Recombination line survey of the Milky Way (THOR) opens a new window to the different parts of the ISM. It enables detailed studies of molecular cloud formation, conversion of atomic to molecular gas, and feedback from Hii regions as well as the magnetic field in the Milky Way. It is highly complementary to other surveys of our Galaxy, and comparing the different datasets

Sensitivity of breast cancer cell lines to recombinant thiaminase I.

Science.gov (United States)

Liu, Shuqian; Monks, Noel R; Hanes, Jeremiah W; Begley, Tadhg P; Yu, Hui; Moscow, Jeffrey A

2010-05-01

We have previously shown that the expression of the thiamine transporter THTR2 is decreased sevenfold in breast cancer, which may leave breast cancer cells vulnerable to acute thiamine starvation. This concept was supported by the observation that MDA231 breast cancer xenografts demonstrated growth inhibition in mice fed a thiamine-free diet. We purified recombinant Bacillus thiaminolyticus thiaminase I enzyme, which digests thiamine, to study acute thiamine starvation in breast cancer. Thiaminase I enzyme was cytotoxic in six breast cancer cell lines with IC(50)s ranging from 0.012 to 0.022 U/ml. The growth inhibitory effects of the combination of thiaminase I with either doxorubicin or paclitaxel were also examined. Over a wide range of drug concentrations, thiaminase 1 was consistently synergistic or additive with doxorubicin and paclitaxel in MCF-7, ZR75, HS578T and T47D cell lines, with most combinations having a calculated combination index (CI) of less than 0.8, indicating synergy. Although thiaminase I exposure did not stimulate the energy-sensing signaling kinases AKT, AMPK and GSK-3beta in MCF-7, ZR75, HS578T and T47D cell lines, thiaminase I exposure did stimulate expression of the ER stress response protein GRP78. In summary, thiaminase I is cytotoxic in breast cancer cell lines and triggers the unfolded protein response. These findings suggest that THTR2 down-regulation in breast tumors may present a nutritional vulnerability that could be exploited by thiaminase I enzyme therapy.

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

Chicken line-dependent mortality after experimental infection with three type IIxIII recombinant Toxoplasma gondii clones.

Science.gov (United States)

Schares, G; Herrmann, D C; Maksimov, P; Matzkeit, B; Conraths, F J; Moré, G; Preisinger, R; Weigend, S

2017-09-01

Three genetically different clones of Toxoplasma gondii, also different in mouse virulence, were studied by experimental infection in chickens. For the experiments, four chicken lines were used, which differed in phylogenetic origin and performance level: two white egg layer lines, one with high laying performance (WLA), one with low (R11) and two brown layer lines, also displaying high (BLA) and low (L68) egg number. Chickens were intraperitoneally infected with three different T. gondii isolates representing type IIxIII recombinant clones, i.e. showing both, type II- and type III-specific alleles. These clones (K119/2 2C10, B136/1 B6H6, K119/2 A7) had exhibited virulence differences in a mouse model. In chickens, a significantly higher mortality was observed in white layer lines, but not in brown layer lines, suggesting that differences in the phylogenetic background may influence the susceptibility of chickens for toxoplasmosis. In addition, antibody (IgY) levels varied in surviving chickens at 31 days post infection. While low to intermediate antibody levels were observed in white layers, intermediate to high levels were measured in brown layers. Infection with a T. gondii clone showing low chicken virulence resulted in higher antibody levels in all chicken lines compared to infection with T. gondii clones of intermediate or high chicken virulence. This was in agreement with the parasite load as determined by real-time PCR. Overall, results show that progeny resulting from natural sexual recombination of T. gondii clonal lineages, may differ in their virulence for mice and chickens. Copyright © 2016 Elsevier Inc. All rights reserved.

The Genetic Basis of Plant Architecture in 10 Maize Recombinant Inbred Line Populations.

Science.gov (United States)

Pan, Qingchun; Xu, Yuancheng; Li, Kun; Peng, Yong; Zhan, Wei; Li, Wenqiang; Li, Lin; Yan, Jianbing

2017-10-01

Plant architecture is a key factor affecting planting density and grain yield in maize ( Zea mays ). However, the genetic mechanisms underlying plant architecture in diverse genetic backgrounds have not been fully addressed. Here, we performed a large-scale phenotyping of 10 plant architecture-related traits and dissected the genetic loci controlling these traits in 10 recombinant inbred line populations derived from 14 diverse genetic backgrounds. Nearly 800 quantitative trait loci (QTLs) with major and minor effects were identified as contributing to the phenotypic variation of plant architecture-related traits. Ninety-two percent of these QTLs were detected in only one population, confirming the diverse genetic backgrounds of the mapping populations and the prevalence of rare alleles in maize. The numbers and effects of QTLs are positively associated with the phenotypic variation in the population, which, in turn, correlates positively with parental phenotypic and genetic variations. A large proportion (38.5%) of QTLs was associated with at least two traits, suggestive of the frequent occurrence of pleiotropic loci or closely linked loci. Key developmental genes, which previously were shown to affect plant architecture in mutant studies, were found to colocalize with many QTLs. Five QTLs were further validated using the segregating populations developed from residual heterozygous lines present in the recombinant inbred line populations. Additionally, one new plant height QTL, qPH3 , has been fine-mapped to a 600-kb genomic region where three candidate genes are located. These results provide insights into the genetic mechanisms controlling plant architecture and will benefit the selection of ideal plant architecture in maize breeding. © 2017 American Society of Plant Biologists. All Rights Reserved.

Temperature dependent recombination dynamics in InP/ZnS colloidal nanocrystals

DEFF Research Database (Denmark)

Shirazi, Roza; Kopylov, Oleksii; Kovács, András

2012-01-01

In this letter, we investigate exciton recombination in InP/ZnS core-shell colloidal nanocrystals over a wide temperature range. Over the entire range between room temperature and liquid helium temperature, multi-exponential exciton decay curves are observed and well explained by the presence...

Laboratory Measurements Of Charge-exchange Produced X-ray Emission From K-shell Transitions In Hydrogenic And Helium-like Fe

Science.gov (United States)

Brown, Gregory V.; Beiersdorfer, P.; Boyce, K. R.; Chen, H.; Gu, M. F.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S.; Thorn, D.; Wargelin, B.

2006-09-01

We have used a microcalorimeter and solid state detectors to measure x-ray emission produced by charge exchange reactions between bare and hydrogenic Fe colliding with neutral helium, hydrogen, and nitrogen gas. We show the measured spectral signature produced by different neutral donors and compare our results to theory where available. We also compare our results to measurements of the Fe K line emission from the Galactic Center measured by the XIS on the Suzaku x-ray observatory. This comparison shows that charge exchange recombination between highly charged ions (either cosmic rays or thermal ions) and neutral gas is probably not the dominant source of diffuse line emission in the Galactic Center. This work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48, and is also supported by NASA APRA grants to LLNL, GSFC, Harvard-Smithsonian CfA, and Stanford University.

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

Analysis of detached recombining plasmas by collisonal-radiative model with energetic electron component

International Nuclear Information System (INIS)

Ohno, N.; Motoyama, M.; Takamura, S.

2001-01-01

Investigation of plasma detachment is still one of the most important subjects in the edge plasma of magnetically confined fusion devices. It was found that volumetric plasma recombination plays an essential role on reduction of particle flux in detached plasmas. The volumetric plasma recombination process has been confirmed in several diverted tokamaks and linear simulators by observing line emission from highly excited states due to three-body recombination process and continuum emission due to radiative recombination process. Electron temperature and density in the detached plasma were also evaluated from analysis of the light emission. To determine the electron temperature, the line emission spectrum is analyzed to calculate the population densities of excited levels. The population distribution among the highly excited states follows the Saha-Boltzmann distribution very closely. This implies that those states are in local thermal equilibrium (LTE) condition with free electrons in plasma so that the electron temperature can be obtained by using method of Boltzmann plot. Another method to determine the electron temperature is to compare the observed continuum spectrum with the theoretically calculated one. In our experiments using the linear diverter simulator, however, there is a clear difference for two evaluated values. One of the possible reasons is thought to be that there is a small amount of energetic electrons existing in detached recombining region. In order to evaluate the electron temperature more preciously, we need to investigate the influence of the energetic electrons on the evaluation of bulk electron temperature in a detached plasma. Collisonal-radiative (GR) model has been utilized for analyzing the light emission intensities from plasma. However, Maxwellian electron distribution function is usually assumed in the CR model. In this paper, we report a quantitative analysis of the line emission spectrum in the detached recombining plasmas by

The Chalk River helium jet and skimmer system

International Nuclear Information System (INIS)

Schmeing, H.; Koslowsky, V.; Wightman, M.; Hardy, J.C.; MacDonald, J.A.; Faestermann, T.; Andrews, H.R.; Geiger, J.S.; Graham, R.L.

1976-01-01

A helium jet and skimmer system intended as an interface between a target location at the Chalk River tandem accelerator and the ion source of an on-line separator presently under construction has been developed. The system consists of a target chamber, a 125 cm long capillary, and a one stage skimmer chamber. The designs of the target and skimmer chambers allow one to vary a large number of independent flow and geometrical parameters with accurate reproducibility. Experiments with the β-delayed proton emitter 25 Si (tsub(1/2)=218 ms) produced in the reaction 24 Mg( 3 He,2n) 25 Si show that under optimized conditions about 75% of the reaction products leaving the target are transported to the skimmer. Of those, more than 90% pass through the skimmer orifice, which separates off 97.5% of the transport gas, helium. By introducing an additional helium flow across the skimming orifice the amount of helium separated off the transport jet can be increased to beyond 99.85%, leaving the high throughput of recoils unaffected. (Auth.)

Heavy metal incorporated helium ion active hybrid non-chemically amplified resists: Nano-patterning with low line edge roughness

Directory of Open Access Journals (Sweden)

Pulikanti Guruprasad Reddy

2017-08-01

Full Text Available Helium (He ion lithography is being considered as one of the most promising and emerging technology for the manufacturing of next generation integrated circuits (ICs at nanolevel. However, He-ion active resists are rarely reported. In this context, we are introducing a new non-chemically amplified hybrid resist (n-CAR, MAPDSA-MAPDST, for high resolution He-ion beam lithography (HBL applications. In the resist architecture, 2.15 % antimony is incorporated as heavy metal in the form of antimonate. This newly developed resists has successfully used for patterning 20 nm negative tone features at a dose of 60 μC/cm2. The resist offered very low line edge roughness (1.27±0.31 nm for 20 nm line features. To our knowledge, this is the first He-ion active hybrid resist for nanopatterning. The contrast (γ and sensitivity (E0 of this resist were calculated from the contrast curve as 0.73 and 7.2 μC/cm2, respectively.

Heavy metal incorporated helium ion active hybrid non-chemically amplified resists: Nano-patterning with low line edge roughness

Science.gov (United States)

Reddy, Pulikanti Guruprasad; Thakur, Neha; Lee, Chien-Lin; Chien, Sheng-Wei; Pradeep, Chullikkattil P.; Ghosh, Subrata; Tsai, Kuen-Yu; Gonsalves, Kenneth E.

2017-08-01

Helium (He) ion lithography is being considered as one of the most promising and emerging technology for the manufacturing of next generation integrated circuits (ICs) at nanolevel. However, He-ion active resists are rarely reported. In this context, we are introducing a new non-chemically amplified hybrid resist (n-CAR), MAPDSA-MAPDST, for high resolution He-ion beam lithography (HBL) applications. In the resist architecture, 2.15 % antimony is incorporated as heavy metal in the form of antimonate. This newly developed resists has successfully used for patterning 20 nm negative tone features at a dose of 60 μC/cm2. The resist offered very low line edge roughness (1.27±0.31 nm) for 20 nm line features. To our knowledge, this is the first He-ion active hybrid resist for nanopatterning. The contrast (γ) and sensitivity (E0) of this resist were calculated from the contrast curve as 0.73 and 7.2 μC/cm2, respectively.

A new set of BXD recombinant inbred lines from advanced intercross populations in mice

Directory of Open Access Journals (Sweden)

Gu Jing

2004-04-01

Full Text Available Abstract Background Recombinant inbred (RI strains are an important resource for mapping complex traits in many species. While large RI panels are available for Arabidopsis, maize, C. elegans, and Drosophila, mouse RI panels typically consist of fewer than 30 lines. This is a severe constraint on the power and precision of mapping efforts and greatly hampers analysis of epistatic interactions. Results In order to address these limitations and to provide the community with a more effective collaborative RI mapping panel we generated new BXD RI strains from two independent advanced intercrosses (AI between C57BL/6J (B6 and DBA/2J (D2 progenitor strains. Progeny were intercrossed for 9 to 14 generations before initiating inbreeding, which is still ongoing for some strains. Since this AI base population is highly recombinant, the 46 advanced recombinant inbred (ARI strains incorporate approximately twice as many recombinations as standard RI strains, a fraction of which are inevitably shared by descent. When combined with the existing BXD RI strains, the merged BXD strain set triples the number of previously available unique recombinations and quadruples the total number of recombinations in the BXD background. Conclusion The combined BXD strain set is the largest mouse RI mapping panel. It is a powerful tool for collaborative analysis of quantitative traits and gene function that will be especially useful to study variation in transcriptome and proteome data sets under multiple environments. Additional strains also extend the value of the extensive phenotypic characterization of the previously available strains. A final advantage of expanding the BXD strain set is that both progenitors have been sequenced, and approximately 1.8 million SNPs have been characterized. This provides unprecedented power in screening candidate genes and can reduce the effective length of QTL intervals. It also makes it possible to reverse standard mapping strategies and

Study of Yield and Effective Traits in Bread Wheat Recombinant Inbred Lines (Triticum aestivum L. under Water Deficit Condition

Directory of Open Access Journals (Sweden)

S. Mohammad zadeh

2013-11-01

Full Text Available The effects some traits on seed yield of recombinant inbred lines of wheat under water deficit stress was studied. This research was done at the Agricultural Research Stations, Islamic Azad University, Tabriz Branch in 2010- 2011. 28 recombinant inbred lines of wheat bread with two parents (Norstar and Zagros in split plot experiment based on a randomized complete block design with three replications at two irrigation levels (70 and 140 mm evaporation from pan class A were studied. Analysis of variance indicated a significant genetic differences in all traits under study among the lines. Lines No. 32, 163 and 182 produced highest yield under both irrigation levels. Number of spikes, grains per spike and harvest index had the highest positive correlation with grain yield. Path analysis based on stepwise regression showed that under the normal irrigation conditions, number spike (0.556, number of grains per spike (0.278, weight of 1000 grain (0.259 and the drought stress number spike (0.430, straw yield (0.276 and peduncle length (0.323 had the most direct and positive effect on yield respectively.

Two 100 m Invar® Transfer Lines at CERN : Design Principles and Operating Experience for Helium Refrigeration

CERN Document Server

Claudet, S; Millet, F; Roussel, E; Sengelin, J P

2005-01-01

The distribution of helium for the Large Hadron Collider (LHC), at CERN, will require a large variety of transfer lines. At the time of qualification of possible technologies, Invar® was investigated as potential material for internal tubes. Intensive developments were made in industry to qualify the use of Invar® M93 and its associated welding parameters. Although all tests showed good perspective, the risk associated with the lack of proven reference turned out to be dissuasive with respect to the possible cost savings for the LHC cryogenic system. However, since DN100 transfer lines were necessary for the supply and return of a test facility over a distance of 100 m, an Invar® based solution was considered, as repair or exchange would have been less dramatic than in the LHC accelerator tunnel. After recalling the technical requirements, the required material qualification will be presented as well as the design principles and operating features. This equipment has been first cooled-down to 4.5 K and acc...

Laser Induced Fluorescence of Helium Ions in a Helicon Plasma

Science.gov (United States)

Compton, C. S.; Biloui, C.; Hardin, R. A.; Keesee, A. M.; Scime, E. E.; Boivin, R.

2003-10-01

The lack of a suitable Laser Induced Fluorescence (LIF) scheme for helium ions at visible wavelengths has prevented LIF from being employed in helium plasmas for measurements of ion temperature and bulk ion flow speeds. In this work, we will discuss our attempts to perform LIF of helium ions in a helicon source plasma using an infrared, tunable diode laser operating at 1012.36 nm. The infrared transition corresponds to excitation from the n = 4 level (4f ^2F) to the n = 5 (5g ^2G) level of singly ionized helium and therefore requires substantial electron temperatures (> 10 eV) to maintain an adequate ion population in the n = 4 state. Calculations using a steady state coronal model predict that the n = 4 state population will be 25% larger than the n = 5 population for our experimental conditions. The fluorescence decay from the n = 5 (5f ^2F) level of singly ionized helium level to the n = 3 (3d ^2D) level at 320.31 nm is monitored as the diode laser is swept through 10 GHz around the 1012.36 nm line. Note that the fluorescence emission requires a collisionally coupled transition between two different n = 5 quantum states. We will also present measurements of the emission intensities of both the 1012.36 nm and the 320.31 nm lines as a function of source neutral pressure, rf power, and plasma density. This work supported by the U.S. DoE EPSCoR Lab Partnership Program.

Radio recombination lines from H+ regions and cold interstellar clouds: computation of the bsub(n) factors

International Nuclear Information System (INIS)

Brocklehurst, M.; Salem, M.

1977-01-01

Emission lines produced by the recombination of hydrogen and hydrogenic ions are observed from many astronomical sources; maser amplification is frequently present. The recombination line spectrum depends upon the populations of the energy levels of the emitting species. The present program computes the ratio, bsub(n), of the population of energy level n to the (known) population in thermodynamic equilibrium for given values of electron temperature and density. A background radiation field may be present. The results are accurate for the range of temperatures and densities associated with cold clouds, H + regions, and planetary nebulae (10-20000 K, 10 -4 -10 6 cm -3 ). The method is that described by Brocklehurst but with the collision cross-sections of Gee et al. In statistical equilibrium, the rates of population and depopulation of each of the infinitely many energy levels must be equal. The infinite system of linear algebraic equations thus defined is truncated, and correction terms are added to compensate for the omitted levels. The resulting system is condensed to a smaller size and solved. The equations of radiative transfer must in principle be solved simultaneously with the population equations. In practice it is uaually sufficient to consider the optical depth for each line to be either zero (no absorption) or infinite (on-the-spot absorption). (Auth.)

A forward model for the helium plume effect and the interpretation of helium charge exchange measurements at ASDEX Upgrade

Science.gov (United States)

Kappatou, A.; McDermott, R. M.; Pütterich, T.; Dux, R.; Geiger, B.; Jaspers, R. J. E.; Donné, A. J. H.; Viezzer, E.; Cavedon, M.; the ASDEX Upgrade Team

2018-05-01

The analysis of the charge exchange measurements of helium is hindered by an additional emission contributing to the spectra, the helium ‘plume’ emission (Fonck et al 1984 Phys. Rev. A 29 3288), which complicates the interpretation of the measurements. The plume emission is indistinguishable from the active charge exchange signal when standard analysis of the spectra is applied and its intensity is of comparable magnitude for ASDEX Upgrade conditions, leading to a significant overestimation of the He2+ densities if not properly treated. Furthermore, the spectral line shape of the plume emission is non-Gaussian and leads to wrong ion temperature and flow measurements when not taken into account. A kinetic model for the helium plume emission has been developed for ASDEX Upgrade. The model is benchmarked against experimental measurements and is shown to capture the underlying physics mechanisms of the plume effect, as it can reproduce the experimental spectra and provides consistent values for the ion temperature, plasma rotation, and He2+ density.

Discrete Visible Luminescence of Helium Atoms and Molecules Desorbing from Helium Clusters: The Role of Electronic, Vibrational, and Rotational Energy Transfer

International Nuclear Information System (INIS)

von Haeften, K.; von Pietrowski, R.; Moeller, T.; Joppien, M.; Moussavizadeh, L.; de Castro, A.R.

1997-01-01

Discrete visible and near-infrared luminescence of a beam of photoexcited helium clusters is reported. The emission lines are attributed to free helium atoms and molecules desorbing from clusters in electronically excited states. Depending on the excitation energy, various atomic and molecular singlet and triplet states are involved in the relaxation process. With increasing cluster size the intensity of molecular transitions becomes dominant. The temperature of ejected molecules could be estimated to T vib ∼2500 K and T rot ∼450 K and is much higher than that of the cluster itself. copyright 1997 The American Physical Society

The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere VI. Helium in the Chromosphere

Directory of Open Access Journals (Sweden)

Robitaille P.-M.

2013-07-01

Full Text Available Molecular hydrogen and hydrides have recently been advanced as vital agents in the generation of emission spectra in the chromosphere. This is a result of the role they play in the formation of condensed hydrogen structures (CHS within the chromosphere (P.M. Robitaille. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere IV. On the Nature of the Chromosphere. Progr. Phys., 2013, v. 3, 15–21. Next to hydrogen, helium is perhaps the most intriguing component in this region of the Sun. Much like other elements, which combine with hydrogen to produce hydrides, helium can form the well-known helium hydride molecular ion, HeH+, and the excited neutral helium hydride molecule, HeH∗. While HeH+ is hypothesized to be a key cosmologicalmolecule, its possible presence in the Sun, and that of its excited neutral counterpart, has not been considered. Still, these hydrides are likely to play a role in the synthesis of CHS, as the He I and He II emission lines strongly suggest. In this regard, the study of helium emission spectra can provide insight into the condensed nature of the Sun, especially when considering the 10830 Å line associated with the 23P→2 3S triplet state transition. This line is strong in solar prominences and can be seen clearly on the disk. The excessive population of helium triplet states cannot be adequately explained using the gaseous models, since these states should be depopulated by collisional processes. Conversely, when He-based molecules are used to build CHS in a liquid metallic hydrogen model, an ever increasing population of the 23S and 23P states might be expected. The overpopulation of these triplet states leads to the conclusion that these emission lines are unlikely to be produced through random collisional or photon excitation, as required by the gaseous models. This provides a significant hurdle for these models. Thus, the strong 23P→2 3S lines and the overpopulation of the helium triplet

Knocking out Ornithine Decarboxylase Antizyme 1 (OAZ1 Improves Recombinant Protein Expression in the HEK293 Cell Line

Directory of Open Access Journals (Sweden)

Laura Abaandou

2018-06-01

Full Text Available Creating efficient cell lines is a priority for the biopharmaceutical industry, which produces biologicals for various uses. A recent approach to achieving this goal is the use of non-coding RNAs, microRNA (miRNA and small interfering RNA (siRNA, to identify key genes that can potentially improve production or growth. The ornithine decarboxylase antizyme 1 (OAZ1 gene, a negative regulator of polyamine biosynthesis, was identified in a genome-wide siRNA screen as a potential engineering target, because its knock down by siRNA increased recombinant protein expression from human embryonic kidney 293 (HEK293 cells by two-fold. To investigate this further, the OAZ1 gene in HEK293 cells was knocked out using CRISPR genome editing. The OAZ1 knockout cell lines displayed up to four-fold higher expression of both stably and transiently expressed proteins, with comparable growth and metabolic activity to the parental cell line; and an approximately three-fold increase in intracellular polyamine content. The results indicate that genetic inactivation of OAZ1 in HEK293 cells is an effective strategy to improve recombinant protein expression in HEK293 cells.

Superfluid helium on on-orbit transfer (SHOOT) flight experiment

International Nuclear Information System (INIS)

DiPirro, M.J.; Kittel, P.

1988-01-01

The SHOOT flight demonstration is being undertaken to verify component and system level technology necessary to resupply large superfluid helium dewars in space. The baseline configuration uses two identical 210 liter dewars connected by a transfer line which contains a quick disconnect coupling. The helium is transferred back and forth between the dewars under various conditions of flow rate, parasitic heat load, and temperature. An astronaut Extra-Vehicular Activity is also planned to manually mate and demate the coupling. The components necessary for the flight and currently being developed are described

Experimental and in silico modelling analyses of the gene expression pathway for recombinant antibody and by-product production in NS0 cell lines.

Science.gov (United States)

Mead, Emma J; Chiverton, Lesley M; Spurgeon, Sarah K; Martin, Elaine B; Montague, Gary A; Smales, C Mark; von der Haar, Tobias

2012-01-01

Monoclonal antibodies are commercially important, high value biotherapeutic drugs used in the treatment of a variety of diseases. These complex molecules consist of two heavy chain and two light chain polypeptides covalently linked by disulphide bonds. They are usually expressed as recombinant proteins from cultured mammalian cells, which are capable of correctly modifying, folding and assembling the polypeptide chains into the native quaternary structure. Such recombinant cell lines often vary in the amounts of product produced and in the heterogeneity of the secreted products. The biological mechanisms of this variation are not fully defined. Here we have utilised experimental and modelling strategies to characterise and define the biology underpinning product heterogeneity in cell lines exhibiting varying antibody expression levels, and then experimentally validated these models. In undertaking these studies we applied and validated biochemical (rate-constant based) and engineering (nonlinear) models of antibody expression to experimental data from four NS0 cell lines with different IgG4 secretion rates. The models predict that export of the full antibody and its fragments are intrinsically linked, and cannot therefore be manipulated individually at the level of the secretory machinery. Instead, the models highlight strategies for the manipulation at the precursor species level to increase recombinant protein yields in both high and low producing cell lines. The models also highlight cell line specific limitations in the antibody expression pathway.

Time evolution of cascade processes of muonic atoms in hydrogen-helium mixtures

International Nuclear Information System (INIS)

Bystritskij, V.; Czaplinski, W.; Filipowicz, M.; Gula, E.; Popov, N.

1999-01-01

Time dependence of population of muonic hydrogen states in hydrogen-helium mixtures is calculated for principal quantum number n. Number of muons transferred to helium nuclei is also determined. Dependence of population of the ground state of muonic hydrogen q ls He on time and target density and helium concentration is also considered. The results are in agreement with recent experimental data. The comparison of the calculated yield of K lines of x-ray in pure hydrogen and deuterium with experimental data indicates on essential role of Coulomb de-excitation process. Possible Stark mixing is also analyzed

Ion temperature anisotropy in high power helium neutral beam fuelling experiments in JET

Energy Technology Data Exchange (ETDEWEB)

Maas, A C; Core, W G.F.; Gerstel, U C; Von Hellermann, M G; Koenig, R W.T.; Marcus, F B [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking

1994-07-01

During helium beam fuelling experiments in JET, distinctive anisotropic features have been observed in the velocity distribution function describing both fast and thermal alpha particle populations. During the initial fuelling phase the central helium ion temperature observed perpendicular to the magnetic field is higher than the central electron temperature, while the central helium ion temperature observed parallel to the magnetic field is lower than or equal to the central electron temperature. In order to verify temperature measurements of both perpendicular and parallel lines of sight, other independent methods of deducing the ion temperature are investigated: deuterium ion temperature, deuterium density, comparison with neutron rates and profiles (influence of a possible metastable population of helium). 6 refs., 7 figs.

Propagative modes along a superfluid helium-4 meniscus

International Nuclear Information System (INIS)

Poujade, M.; Guthmann, C.; Rolley, E.

2002-01-01

We have studied the dynamics of a superfluid helium-4 meniscus on a solid substrate. In a pseudo-non-wetting situation, there is no hysteresis of the contact angle. We show that distortions of a liquid meniscus do propagate along the contact line. We have analyzed the propagation of pulses. We find a good agreement with theoretical predictions by Brochard for the dispersion relation of oscillation modes of the contact line. (authors)

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.

Membrane pumping technology, helium and hydrogen isotopes separation in the fusion hydrogen

International Nuclear Information System (INIS)

Pigarov, A.Yu.; Pistunovich, V.I.; Busnyuk, A.O.

1994-01-01

A gas pumping system for the ITER, improved by implementation of superpermeable membranes for selective hydrogen isotope exhaust, is considered. The study of the pumping capability of a niobium membrane for a hydrogen-helium mixture has been fulfilled. The membrane superpermeability can be only realized for atomic hydrogen. Helium does not pass through the membrane, and its presence does not affect the hydrogen pumping. A detailed Monte Carlo simulation of gas behavior for the experimental facility has been done. The probability of permeation for a hydrogen atom for one collision with the membrane is ∼0.1; the same probability of molecule permeation is ∼10 -5 . The probability for atomization, i.e. re-emission of an atomizer is ∼0.2; the probability of recombination of an atom is ∼0.2

Ejecta Particle-Size Measurements in Vacuum and Helium Gas using Ultraviolet In-Line Fraunhofer Holography

Energy Technology Data Exchange (ETDEWEB)

Sorenson, Danny S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pazuchanics, Peter [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Johnson, Randall P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Malone, R. M. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Kaufman, M. I. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Tibbitts, A. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Tunnell, T. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Marks, D. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Capelle, G. A. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Grover, M. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Marshall, B. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Stevens, G. D. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Turley, W. D. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); LaLone, B. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States)

2014-06-25

An Ultraviolet (UV) in-line Fraunhofer holography diagnostic has been developed for making high-resolution spatial measurements of ejecta particles traveling at many mm/μsec. This report will discuss the development of the diagnostic including the high-powered laser system and high-resolution optical relay system. In addition, the system required to reconstruct the images from the hologram and the corresponding analysis of those images to extract particles will also be described. Finally, results from six high-explosive (HE), shock-driven Sn ejecta experiments will be presented. Particle size distributions will be shown that cover most of the ejecta velocities for experiments conducted in a vacuum, and helium gas environments. In addition, a modification has been made to the laser system that produces two laser pulses separated by 6.8 ns. This double-pulsed capability allows a superposition of two holograms to be acquired at two different times, thus allowing ejecta velocities to be measured directly. Results from this double pulsed experiment will be described.

A new approach to systematic uncertainties and self-consistency in helium abundance determinations

International Nuclear Information System (INIS)

Aver, Erik; Olive, Keith A.; Skillman, Evan D.

2010-01-01

Tests of big bang nucleosynthesis and early universe cosmology require precision measurements for helium abundance determinations. However, efforts to determine the primordial helium abundance via observations of metal poor H II regions have been limited by significant uncertainties (compared with the value inferred from BBN theory using the CMB determined value of the baryon density). This work builds upon previous work by providing an updated and extended program in evaluating these uncertainties. Procedural consistency is achieved by integrating the hydrogen based reddening correction with the helium based abundance calculation, i.e., all physical parameters are solved for simultaneously. We include new atomic data for helium recombination and collisional emission based upon recent work by Porter \\etal and wavelength dependent corrections to underlying absorption are investigated. The set of physical parameters has been expanded here to include the effects of neutral hydrogen collisional emission. It is noted that Hγ and Hδ allow better isolation of the collisional effects from the reddening. Because of a degeneracy between the solutions for density and temperature, the precision of the helium abundance determinations is limited. Also, at lower temperatures (T ∼ p as 0.2561 ± 0.0108, in broad agreement with the WMAP result. Alternatively, a simple average of the data yields Y p 0.2566 ± 0.0028. Tests with synthetic data show a potential for distinct improvement, via removal of underlying absorption, using higher resolution spectra. A small bias in the abundance determination can be reduced significantly and the calculated helium abundance error can be reduced by ∼ 25%

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

Determination of electron temperature and density at plasma edge in the Large Helical Device with opacity-incorporated helium collisional-radiative model

International Nuclear Information System (INIS)

Goto, M.; Sawada, K.

2014-01-01

Spectra of neutral helium in the visible wavelength range are measured for a discharge in the Large Helical Device (LHD). The electron temperature (T e ) and density (n e ) are derived from the intensity distribution of helium emission lines. For that purpose, a collisional-radiative model developed by Sawada et al. [Plasma and Fusion Res. 2010;5:001] which takes the reabsorption effect into account is used. It is found that incorporation of the reabsorption effect is necessary to obtain a set of T e and n e giving consistent line intensity distribution with the measurement, and that those parameters obtained vary as the line-averaged n e changes in the course of time. The position where the helium line emission dominantly takes place is located with the help of T e and n e profiles measured by the Thomson scattering system. The result indicates that the emission position is almost fixed at the place where the connection length of the magnetic field lines to the divertor plate leaps beyond 10 m. Because intense neutral atom line emission suggests the vigorous ionization of neutral atoms, the helium line emission location determined here can be regarded as the effective boundary of the plasma. - Highlights: • The reabsorption effect is included in the helium collisional-radiative model. • Electron temperature and density are derived for the Large Helical Device (LHD). • Line emission location is found to be little changed during the discharge. • This measurement method can be used to determine the position of effective plasma boundary

Evaluation of Grain Quality in Bread Wheat Recombinant Inbred Lines Under Drought Stress Conditions

Directory of Open Access Journals (Sweden)

H. Shahbazi

2014-04-01

Full Text Available To study drought stress effect on grain quality properties of wheat, an experiment was conductedusing 169 recombinant inbreed lines (RILS under water stress and non-stress condition and with two separated lattice designs. Grain yield, protein yield, protein content, volume of Zeleny sediment, grain hardness, water absorption, grain moisture content and grain dry matter were evaluated. Analysis of variance showed that there were significant differences among the lines for all traits. Moreover, comparison between two lines in two environmental conditions showed, the quality in bread wheat under drought stress conditions due to increment of protein yield is improved. Protein yield in both irrigation regimes has a significant and negative correlation with grain moisture and in the other hand, significant and positive correlation with the grain hardiness dry matter, Zeleny sedimentation and water intake in both conditions. The results showed that the identification of favorable quality characteristics in optimum and stressed conditions were possible and the lines with high grain quality can be used in breeding programs for improving of baking quality. Although some drought sensitive genotypes possessed a favorable baking quality but their grain yield was low.

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...

Space and time resolved measurements of ion temperature with the CVI 5292 A charge exchange recombination line after subtracting background radiation

International Nuclear Information System (INIS)

Ida, K.; Hidekuma, S.

1988-08-01

An ion temperature profile has been obtained with the CVI 5292 A (n = 8 - 7) charge exchange recombination (CXR) line using a space and wave-length resolving visible spectrometer installed on the JIPP TII-U tokamak. Two sets of 50 channels optical fiber arrays: one viewing a fast neutral hydrogen beam (CXR channels) and the other viewing off the neutral beam line (background channels), is arranged on the entrance slit of the spectrometer. This spectrometer is coupled to an image intensifier and CCD detector at the focal plane and provides temperature profile every 1/60 second. An ion temperature is derived from the Doppler broadened line profile after subtracting the simultaneously measured cold component (background channels), which is due to electron-excitation and/or charge exchange recombination in the plasma periphery. Alternative approach to obtain the ion temperature profile without CXR is also demonstrated. This method is based on an Abel inversion technique for each wavelength separately. (author)

Generation of a Chinese Hamster Ovary Cell Line Producing Recombinant Human Glucocerebrosidase

Science.gov (United States)

Novo, Juliana Branco; Morganti, Ligia; Moro, Ana Maria; Paes Leme, Adriana Franco; Serrano, Solange Maria de Toledo; Raw, Isaias; Ho, Paulo Lee

2012-01-01

Impaired activity of the lysosomal enzyme glucocerebrosidase (GCR) results in the inherited metabolic disorder known as Gaucher disease. Current treatment consists of enzyme replacement therapy by administration of exogenous GCR. Although effective, it is exceptionally expensive, and patients worldwide have a limited access to this medicine. In Brazil, the public healthcare system provides the drug free of charge for all Gaucher's patients, which reaches the order of $ 84 million per year. However, the production of GCR by public institutions in Brazil would reduce significantly the therapy costs. Here, we describe a robust protocol for the generation of a cell line producing recombinant human GCR. The protein was expressed in CHO-DXB11 (dhfr−) cells after stable transfection and gene amplification with methotrexate. As expected, glycosylated GCR was detected by immunoblotting assay both as cell-associated (~64 and 59 kDa) and secreted (63–69 kDa) form. Analysis of subclones allowed the selection of stable CHO cells producing a secreted functional enzyme, with a calculated productivity of 5.14 pg/cell/day for the highest producer. Although being laborious, traditional methods of screening high-producing recombinant cells may represent a valuable alternative to generate expensive biopharmaceuticals in countries with limited resources. PMID:23091360

Generation of a Chinese Hamster Ovary Cell Line Producing Recombinant Human Glucocerebrosidase

Directory of Open Access Journals (Sweden)

Juliana Branco Novo

2012-01-01

Full Text Available Impaired activity of the lysosomal enzyme glucocerebrosidase (GCR results in the inherited metabolic disorder known as Gaucher disease. Current treatment consists of enzyme replacement therapy by administration of exogenous GCR. Although effective, it is exceptionally expensive, and patients worldwide have a limited access to this medicine. In Brazil, the public healthcare system provides the drug free of charge for all Gaucher’s patients, which reaches the order of $ 84 million per year. However, the production of GCR by public institutions in Brazil would reduce significantly the therapy costs. Here, we describe a robust protocol for the generation of a cell line producing recombinant human GCR. The protein was expressed in CHO-DXB11 (dhfr− cells after stable transfection and gene amplification with methotrexate. As expected, glycosylated GCR was detected by immunoblotting assay both as cell-associated (~64 and 59 kDa and secreted (63–69 kDa form. Analysis of subclones allowed the selection of stable CHO cells producing a secreted functional enzyme, with a calculated productivity of 5.14 pg/cell/day for the highest producer. Although being laborious, traditional methods of screening high-producing recombinant cells may represent a valuable alternative to generate expensive biopharmaceuticals in countries with limited resources.

Helium shell flashes and ionization of planetary nebulae. Pt. 2. FG Sge

International Nuclear Information System (INIS)

Tylenda, R.

1980-01-01

Theoretical models have been constructed to study time-dependent effects in the nebulae (He 1-5) associated with FG Sge. Two cases have been considered: recombination of an initially stationary nebula of moderate excitation (Case A), and nonequilibrium ionization (and subsequent recombination) of an initially neutral nebula by a thermal pulse in the central star (Case B). Comparison with the observed spectrum does not allow to distinguish definitely between both cases. There are slight indications that the present state of He 1-5 is better reproduced in Case B which is also preferable from the point of view of the present theoretical knowledge of observational appearances of helium shell flashes in planetary nebula nuclei. The nebula has a normal chemical composition. (author)

Study and simulation of the behaviour under irradiation of helium in uranium dioxide; Etude et modelisation du comportement sous irradiation de l'helium dans le dioxyde d'uranium

Energy Technology Data Exchange (ETDEWEB)

Martin, G

2007-06-15

Large quantities of helium are produced from {alpha}-decay of actinides in nuclear fuels during its in-pile operating and its storage. It is important to understand the behaviour of helium in these matrix in order to well simulate the evolution and the resistance of the fuel element. During this thesis, we have used nuclear reaction analyses (NRA) to follow the evolution of the helium implanted in polycrystalline and monocrystalline uranium dioxide (UO{sub 2}). An experimental rig was developed to follow the on-line helium release in UO{sub 2} and the evolution of {sup 3}He profiles as a function of annealing temperature. An automated procedure taking into account the evolution of the depth resolution was developed. Analyses performed with a nuclear microprobe allowed to characterise the spatial distribution of helium at the grain scale and to study the influence of the sample microstructure on the helium migration. This work put into evidence the particular role of grain boundaries and irradiation defects in the helium release process. The analyse of experimental results with a diffusion model corroborates these interpretations. It allowed to determine quantitatively physical properties that characterise the helium behaviour in uranium dioxide (diffusion coefficient, activation energy..). (author)

Displacements and intensities of the components of hydrogenic lines of the helium atom in the presence of exterior uniform electrical and magnetic fields; Deplacements et intensites des composantes des raies hydrogenoides de l'atome d'helium en presence de champs exterieurs electrique et magnetique uniformes

Energy Technology Data Exchange (ETDEWEB)

Deutsch, C; Herman, L; Nguyen, H [Laboratoire de Recherches Physiques, 75 - Paris (France); Drawin, H W [Commissariat a l' Energie Atomique, Association Euratom-CEA, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1967-07-01

The Waller-Foster method for hydrogenic lines of neutral helium is extended in order to take into account an external magnetic field (vector K) having an arbitrary angle with an external constant electric field (vector F). The diagonal correction has been evaluated numerically taking into account recent experimental data. A Fortran IV program written for the CDC 3600 computer allows to calculate the displacements and the intensities for any hydrogenic transition. Special attention is given to the {l_brace}2-4{r_brace} transitions in neutral helium. (authors) [French] La methode de perturbation de Waller et Foster est generalisee afin de tenir compte d'un champ magnetique exterieur (vecteurK) faisant un angle quelconque avec un champ electrique exterieur (vecteurF). La correction diagonale des matrices de perturbation est evaluee numeriquement a l'aide des donnees atomiques les plus recentes. Un programme ecrit pour l'ordinateur CDC 3600 permet le calcul des deplacements et des intensites pour des transitions hydrogenoides quelconques. Les transitions [2-4]d'helium neutre ont ete etudiees plus particulierement. (auteurs)

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.

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

DETECTION OF FORBIDDEN LINE COMPONENTS OF LITHIUM-LIKE CARBON IN STELLAR SPECTRA

Energy Technology Data Exchange (ETDEWEB)

Werner, Klaus; Rauch, Thomas; Hoyer, Denny [Institute for Astronomy and Astrophysics, Kepler Center for Astro and Particle Physics, Eberhard Karls University Tübingen, Sand 1, D-72076 Tübingen (Germany); Quinet, Pascal [Physique Atomique et Astrophysique, Université de Mons—UMONS, B-7000 Mons (Belgium)

2016-08-10

We report the first identification of forbidden line components from an element heavier than helium in the spectrum of astrophysical plasmas. So far, these components were identified only in laboratory plasmas and not in astrophysical objects. Forbidden components are well known for neutral helium lines in hot stars, particularly in helium-rich post-AGB stars and white dwarfs. We discovered that two hitherto unidentified lines in the ultraviolet spectra of hot hydrogen-deficient (pre-) white dwarfs can be identified as forbidden line components of triply ionized carbon (C iv). The forbidden components (3p–4f and 3d–4d) appear in the blue and red wings of the strong, Stark broadened 3p–4d and 3d–4f lines at 1108 Å and 1169 Å, respectively. They are visible over a wide effective temperature range (60,000–200,000 K) in helium-rich (DO) white dwarfs and PG 1159 stars that have strongly oversolar carbon abundances.

The Story of Helium and the Birth of Astrophysics

CERN Document Server

Nath, Biman B

2013-01-01

Biman Nath The Story of Helium and the Birth of Astrophysics Helium was the first element ever discovered by astronomers. Its presence was first indicated in the Sun and not on Earth. Further, its discovery marked the birth of the new science of astrophysics. However, it turns out that the events leading to the discovery of helium have been rather misrepresented in books, journals, and even encyclopedias. The usual story about its joint discovery during a solar eclipse in 1868 by French astronomer Pierre Janssen and late in England by Norman Lockyer, is far from the truth. Janssen never mentioned any new spectral line in his reports. The actual story turns out to be as dramatic as in fiction. This book tells the story without jargon, using the words of the scientists themselves (from their letters and reports), and rescues the real story from the backwaters of history.

The influence of continuum radiation fields on hydrogen radio recombination lines

Science.gov (United States)

Prozesky, Andri; Smits, Derck P.

2018-05-01

Calculations of hydrogen departure coefficients using a model with the angular momentum quantum levels resolved that includes the effects of external radiation fields are presented. The stimulating processes are important at radio frequencies and can influence level populations. New numerical techniques with a solid mathematical basis have been incorporated into the model to ensure convergence of the solution. Our results differ from previous results by up to 20 per cent. A direct solver with a similar accuracy but more efficient than the iterative method is used to evaluate the influence of continuum radiation on the hydrogen population structure. The effects on departure coefficients of continuum radiation from dust, the cosmic microwave background, the stellar ionising radiation, and free-free radiation are quantified. Tables of emission and absorption coefficients for interpreting observed radio recombination lines are provided.

Germline recombination in a novel Cre transgenic line, Prl3b1-Cre mouse.

Science.gov (United States)

Al-Soudy, Al-Sayed; Nakanishi, Tsuyoshi; Mizuno, Seiya; Hasegawa, Yoshikazu; Shawki, Hossam H; Katoh, Megumi C; Basha, Walaa A; Ibrahim, Abdelaziz E; El-Shemy, Hany A; Iseki, Hiroyoshi; Yoshiki, Atsushi; Hiromori, Youhei; Nagase, Hisamitsu; Takahashi, Satoru; Oishi, Hisashi; Sugiyama, Fumihiro

2016-07-01

Spermatogenesis is a complex and highly regulated process by which spermatogonial stem cells differentiate into spermatozoa. To better understand the molecular mechanisms of the process, the Cre/loxP system has been widely utilized for conditional gene knockout in mice. In this study, we generated a transgenic mouse line that expresses Cre recombinase under the control of the 2.5 kbp of the Prolactin family 3, subfamily b, member 1 (Prl3b1) gene promoter (Prl3b1-cre). Prl3b1 was initially reported to code for placental lactogen 2 (PL-2) protein in placenta along with increased expression toward the end of pregnancy. PL-2 was found to be expressed in germ cells in the testis, especially in spermatocytes. To analyze the specificity and efficiency of Cre recombinase activity in Prl3b1-cre mice, the mice were mated with reporter R26GRR mice, which express GFP ubiquitously before and tdsRed exclusively after Cre recombination. The systemic examination of Prl3b1-cre;R26GRR mice revealed that tdsRed-positive cells were detected only in the testis and epididymis. Fluorescence imaging of Prl3b1-cre;R26GRR testes suggested that Cre-mediated recombination took place in the germ cells with approximately 74% efficiency determined by in vitro fertilization. In conclusion, our results suggest that the Prl3b1-cre mice line provides a unique resource to understand testicular germ-cell development. genesis 54:389-397, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Binary and ternary recombination of D3+ ions at 80-130 K: Application of laser absorption spectroscopy

Science.gov (United States)

Dohnal, Petr; Hejduk, Michal; Rubovič, Peter; Varju, Jozef; Roučka, Štěpán; Plašil, Radek; Glosík, Juraj

2012-11-01

Recombination of D_3^+ ions with electrons at low temperatures (80-130 K) was studied using spectroscopic determination of D_3^+ ions density in afterglow plasmas. The use of cavity ring-down absorption spectroscopy enabled an in situ determination of the abundances of the ions in plasma and the translational and the rotational temperatures of the recombining ions. Two near infrared transitions at (5792.70 ± 0.01) cm-1 and at (5793.90 ± 0.01) cm-1 were used to probe the number densities of the lowest ortho state and of one higher lying rotational state of the vibrational ground state of D_3^+ ion. The results show that D_3^+ recombination with electrons consists of the binary and the third-body (helium) assisted process. The obtained binary recombination rate coefficients are in agreement with a recent theoretical prediction for electron-ion plasma in thermodynamic equilibrium with αbin(80 K) = (9.2 ± 2.0) × 10-8 cm3 s-1. The measured helium assisted ternary rate coefficients KHe are in agreement with our previously measured flowing afterglow data giving a value of KHe(80 K) = (1.2 ± 0.3) × 10-25 cm6 s-1.

Binary and ternary recombination of D3+ ions at 80-130 K: application of laser absorption spectroscopy.

Science.gov (United States)

Dohnal, Petr; Hejduk, Michal; Rubovič, Peter; Varju, Jozef; Roučka, Štěpán; Plašil, Radek; Glosík, Juraj

2012-11-21

Recombination of D(3)(+) ions with electrons at low temperatures (80-130 K) was studied using spectroscopic determination of D(3)(+) ions density in afterglow plasmas. The use of cavity ring-down absorption spectroscopy enabled an in situ determination of the abundances of the ions in plasma and the translational and the rotational temperatures of the recombining ions. Two near infrared transitions at (5792.70 ± 0.01) cm(-1) and at (5793.90 ± 0.01) cm(-1) were used to probe the number densities of the lowest ortho state and of one higher lying rotational state of the vibrational ground state of D(3)(+) ion. The results show that D(3)(+) recombination with electrons consists of the binary and the third-body (helium) assisted process. The obtained binary recombination rate coefficients are in agreement with a recent theoretical prediction for electron-ion plasma in thermodynamic equilibrium with α(bin)(80 K) = (9.2 ± 2.0) × 10(-8) cm(3) s(-1). The measured helium assisted ternary rate coefficients K(He) are in agreement with our previously measured flowing afterglow data giving a value of K(He)(80 K) = (1.2 ± 0.3) × 10(-25) cm(6) s(-1).

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...

Characterization of an Sf-rhabdovirus-negative Spodoptera frugiperda cell line as an alternative host for recombinant protein production in the baculovirus-insect cell system.

Science.gov (United States)

Maghodia, Ajay B; Geisler, Christoph; Jarvis, Donald L

2016-06-01

Cell lines derived from the fall armyworm, Spodoptera frugiperda (Sf), are widely used as hosts for recombinant protein production in the baculovirus-insect cell system (BICS). However, it was recently discovered that these cell lines are contaminated with a virus, now known as Sf-rhabdovirus [1]. The detection of this adventitious agent raised a potential safety issue that could adversely impact the BICS as a commercial recombinant protein production platform. Thus, we examined the properties of Sf-RVN, an Sf-rhabdovirus-negative Sf cell line, as a potential alternative host. Nested RT-PCR assays showed Sf-RVN cells had no detectable Sf-rhabdovirus over the course of 60 passages in continuous culture. The general properties of Sf-RVN cells, including their average growth rates, diameters, morphologies, and viabilities after baculovirus infection, were virtually identical to those of Sf9 cells. Baculovirus-infected Sf-RVN and Sf9 cells produced equivalent levels of three recombinant proteins, including an intracellular prokaryotic protein and two secreted eukaryotic glycoproteins, and provided similar N-glycosylation patterns. In fact, except for the absence of Sf-rhabdovirus, the only difference between Sf-RVN and Sf9 cells was SF-RVN produced higher levels of infectious baculovirus progeny. These results show Sf-RVN cells can be used as improved, alternative hosts to circumvent the potential safety hazard associated with the use of Sf-rhabdovirus-contaminated Sf cells for recombinant protein manufacturing with the BICS. Copyright © 2016 Elsevier Inc. All rights reserved.

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)

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.)

A statistical study of coronal densities from X-ray line ratios of helium-like ions - Ne IX and Mg XI

Science.gov (United States)

Linford, G. A.; Lemen, J. R.; Strong, K. T.

1988-01-01

Since the repair of the Solar Maximum Mission (SMM) spacecraft, the Flat Crystal Spectrometer (FCS) has recorded many high temperature spectra of helium-like ions under a wide variety of coronal conditions including active regions, long duration events, compact events, and double flares. The plasma density and temperature are derived from the ratios R and G, where R = f/i, G = (f + i)/r, and r, f, and i denote the resonance, forbidden, and intercombination line fluxes. A new method for obtaining the density and temperature for events observed with the FCS aboard SMM is presented. The results for these events are presented and compared to earlier results, and the method is evaluated based on these comparisons.

The use of cryogenic helium for classical turbulence: Promises and hurdles

International Nuclear Information System (INIS)

Niemela, J.J.; Sreenivasan, K.R.

2006-12-01

Fluid turbulence is a paradigm for non-linear systems with many degrees of freedom and important in numerous applications. Because the analytical understanding of the equations of motion is poor, experiments and, lately, direct numerical simulations of the equations of motion, have been fundamental to making progress. In this vein, a concerted experimental effort has been made to take advantage of the unique properties of liquid and gaseous helium at low temperatures near or below the critical point. We discuss the promise and impact of results from recent helium experiments and identify the current technical barriers which can perhaps be removed by low temperature researchers. We focus mainly on classical flows that utilize helium above the lambda line, but touch on those aspects below that exhibit quasi-classical behavior. (author)

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.

Damage, trapping and desorption at the implantation of helium and deuterium in graphite, diamond and silicon carbide

International Nuclear Information System (INIS)

Lopez, G.A.R.

1995-07-01

The production, thermal stability and structure of ion induced defects have been studied by Rutherford backscattering in channeling geometry for the implantation of helium and deuterium in graphite, diamond and silicon carbide with energies of 8 and 20 keV. At the implantation of deuterium and helium ions more defects were measured in graphite than in diamond or silicon carbide at equal experimental conditions. This is due to increased backscattering in graphite, which is caused by the splitting and tilting of crystallites and a local reordering of lattice atoms around defects. At 300 K, Helium produces more defects in all three materials than deuterium with equal depth distribution of defects. The ratio of the defects produced by helium and deuterium agrees very well with the corresponding ratio of the energy deposited in nuclear collisions. In graphite, only small concentrations of deuterium induced defects anneal below 800 K, while in diamond small concentrations of deuterium as well as of helium induced defects anneal mostly below 800 K. This annealing behavior is considered to be due to recombination of point defects. The buildup of helium and deuterium in graphite is different. The trapping of deuterium proceeds until saturation is reached, while in the case of helium trapping is interrupted by flaking. In diamond, deuterium as well as helium are trapped almost completely until at higher fluences reemission starts and saturation is reached. Two desorption mechanisms were identified for the thermal desorption of helium from base-oriented graphite. Helium implanted at low fluences desorbs diffusing to the surface, while for the implantation of high fluences the release of helium due to blistering dominates. The desorption of deuterium from graphite and diamond shows differences. While in graphite the desorption starts already at 800 K, in diamond up to 1140 K only little desorption can be observed. These differences can be explained by the different transport

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

Two-dimensional imaging of edge plasma electron density and temperature by the passive helium emission ratio technique in TJ-II

International Nuclear Information System (INIS)

De la Cal, E; Guasp, J

2011-01-01

An intensified visible camera looks tangentially at a poloidal limiter where helium recycles, acting as a wide neutral source, and the atomic line emission due to plasma excitation becomes strongly localized there. It includes a bifurcated coherent bundle, each end with a different interference filter to select helium atomic lines, so that two simultaneous filtered images are captured in one single frame. The object of the proposed technique is to apply the well-known helium-beam line-ratio technique to obtain from selected filtered images the two-dimensional (2D) edge plasma n e and T e . The code EIRENE was used to demonstrate that the helium emission from recycling neutrals dominates the emission for the lines of view passing close above the limiter. Since these chords are nearly parallel to magnetic field lines in the emission region, the images can be approximated to poloidal cuts of the plasma emission within the tolerances discussed in the paper. The absolute radial profiles of T e and n e obtained with the method presented here were checked in the TJ-II stellarator to be in relatively good agreement with other diagnostics within a wide range of plasma parameters for both ECRH and NBI plasmas. The method is finally used to get 2D images of edge plasma T e and n e .

Influence of the helium-pressure on diode-pumped alkali-vapor laser

Science.gov (United States)

Gao, Fei; Chen, Fei; Xie, Ji-jiang; Zhang, Lai-ming; Li, Dian-jun; Yang, Gui-long; Guo, Jing

2013-05-01

Diode-pumped alkali-vapor laser (DPAL) is a kind of laser attracted much attention for its merits, such as high quantum efficiency, excellent beam quality, favorable thermal management, and potential scalability to high power and so on. Based on the rate-equation theory of end-pumped DPAL, the performances of DPAL using Cs-vapor collisionally broadened by helium are simulated and studied. With the increase of helium pressure, the numerical results show that: 1) the absorption line-width increases and the stimulated absorption cross-section decreases contrarily; 2) the threshold pumping power decreases to minimum and then rolls over to increase linearly; 3) the absorption efficiency rises to maximum initially due to enough large stimulated absorption cross-section in the far wings of collisionally broadened D2 transition (absorption transition), and then begins to reduce; 4) an optimal value of helium pressure exists to obtain the highest output power, leading to an optimal optical-optical efficiency. Furthermore, to generate the self-oscillation of laser, a critical value of helium pressure occurs when small-signal gain equals to the threshold gain.

Theory of surface recombination of spin-polarized hydrogen

International Nuclear Information System (INIS)

Christou, C.T.; Haftel, M.I.

1989-01-01

A theory is presented, based on the Faddeev equations, for direct two-body recombination of hydrogen atoms on a liquid helium surface. The equations developed are applicable to hydrogen or deuterium atoms in any spin state, but are applied in particular to dipolar recombination of b state hydrogen atoms. The equations yield terms corresponding to one- and two-step processes. These terms are calculated for low temperatures (T = 0.1 to 1.1 K) and high field strengths (B = 4 to 14 T). The one-step term increases slowly with B, while the two-step term is rapidly decreasing. While the overall rate is quite small (∼5 x 10 -18 cm 2 /s) compared to recombination by two-body spin-relaxation, the results have important consequences in understanding the experimentally measured three-atom dipolar surface recombination rates. In three-atom recombination, where the role of spin-relaxation and the two-atom one-step processes are repressed, the role of the underlying two-atom, two-step process is enhanced. The field dependence of the process relevant to the three-atom system is calculated and found to be in fairly good agreement with the experimental three-atom data. The role of possible liquid excitations in enhancing the contribution of the two-step processes is also discussed. 33 refs.; 1 figure; 6 tabs

Dissection of Recombination Attributes for Multiple Maize Populations Using a Common SNP Assay

Directory of Open Access Journals (Sweden)

Haiying Guan

2017-11-01

Full Text Available Recombination is a vital characteristic for quantitative trait loci mapping and breeding to enhance the yield potential of maize. However, recombination characteristics in globally used segregating populations have never been evaluated at similar genetic marker densities. This study aimed to divulge the characteristics of recombination events, recombinant chromosomal segments, and recombination frequency for four dissimilar populations. These populations were doubled haploid (DH, recombination inbred line (RIL, intermated B73xMo17 (IBM, and multi-parent advanced generation inter-cross (MAGIC, using the Illumina MaizeSNP50 BeadChip to provide markers. Our results revealed that the average number of recombination events was 16, 41, 72, and 86 per line in DH, RIL, IBM, and MAGIC populations, respectively. Accordingly, the average length of recombinant chromosomal segments was 84.8, 47.3, 29.2, and 20.4 Mb in DH, RIL, IBM, and MAGIC populations, respectively. Furtherly, the recombination frequency varied in different genomic regions and population types [DH (0–12.7 cM/Mb, RIL (0–15.5 cM/Mb, IBM (0–24.1 cM/Mb, MAGIC (0–42.3 cM/Mb]. Utilizing different sub-sets of lines, the recombination bin number and size were analyzed in each population. Additionally, different sub-sets of markers and lines were employed to estimate the recombination bin number and size via formulas for relationship in these populations. The relationship between recombination events and recombination bin length was also examined. Our results contribute to determining the most suitable number of genetic markers, lines in each population, and population type for successful mapping and breeding.

Laser spectroscopy of Ag atoms in liquid helium and gaseous helium at low temperatures

International Nuclear Information System (INIS)

Hui, Q.; Persson, J. L.; Jakubek, Z. J.; Takami, M.

1998-01-01

Neutral Ag atoms are dispersed in liquid and gaseous helium by laser ablation and dissociation. Following the excitation of the D2 line, a broad emission band is observed to the red side of the D1 emission line. This band is assigned to the A 2 Π 3/2 → X 2 Σ + bound-free transition of the AgHe 2 exciplex. The assignment has been confirmed by an ab initio calculation on the AgHe 2 complex. The temperature and the pressure dependences of the D1 emission and the broad emission in the gas phase indicate that the 4d 9 5s 2 2 D 5/2 level may play an important role in the 5p 2 P 3/2 → 5p 2 1/2 non-radiative relaxation and the exciplex formation processes

Collisional-radiative model including recombination processes for W27+ ion★

Science.gov (United States)

Murakami, Izumi; Sasaki, Akira; Kato, Daiji; Koike, Fumihiro

2017-10-01

We have constructed a collisional-radiative (CR) model for W27+ ions including 226 configurations with n ≤ 9 and ł ≤ 5 for spectroscopic diagnostics. We newly include recombination processes in the model and this is the first result of extreme ultraviolet spectrum calculated for recombining plasma component. Calculated spectra in 40-70 Å range in ionizing and recombining plasma components show similar 3 strong lines and 1 line weak in recombining plasma component at 45-50 Å and many weak lines at 50-65 Å for both components. Recombination processes do not contribute much to the spectrum at around 60 Å for W27+ ion. Dielectronic satellite lines are also minor contribution to the spectrum of recombining plasma component. Dielectronic recombination (DR) rate coefficient from W28+ to W27+ ions is also calculated with the same atomic data in the CR model. We found that larger set of energy levels including many autoionizing states gave larger DR rate coefficients but our rate agree within factor 6 with other works at electron temperature around 1 keV in which W27+ and W28+ ions are usually observed in plasmas. Contribution to the Topical Issue "Atomic and Molecular Data and their Applications", edited by Gordon W.F. Drake, Jung-Sik Yoon, Daiji Kato, and Grzegorz Karwasz.

Magneto-optical trap for metastable helium at 389 nm

NARCIS (Netherlands)

Koelemeij, J.C.J.; Stas, R.J.W.; Hogervorst, W.; Vassen, W.

2003-01-01

We have constructed a magneto-optical trap (MOT) for metastable triplet helium atoms utilizing the 2 S-3(1)-->3 P-3(2) line at 389 nm as the trapping and cooling transition. The far-red-detuned MOT (detuning Delta=-41 MHz) typically contains few times 10(7) atoms at a relatively high (similar

Genetic mapping of QTLs associated with seed macronutrients accumulation in 'MD96-5722' by 'Spencer' recombinant inbred lines of soybean

Science.gov (United States)

Research of genetic mapping of QTLs for macronutrient accumulation in soybean seed is limited. Therefore, the objective of this research was to identify QTLs related to macronutrients (N, C, S, P, K, Ca, and Mg) in seeds in 92 F5:7 recombinant inbred lines developed from a cross between MD 96-5722 (...

Helium leak testing of superconducting magnets, thermal shields and cryogenic lines of SST -1

International Nuclear Information System (INIS)

Thankey, P.L.; Joshi, K.S.; Semwal, P.; Pathan, F.S.; Raval, D.C.; Khan, Z.; Patel, R.J.; Pathak, H.A.

2005-01-01

Tokamak SST - 1 is under commissioning at Institute for Plasma Research. It comprises of a toroidal doughnut shaped plasma chamber, surrounded by liquid helium cooled superconducting magnets, housed in a cryostat chamber. The cryostat has two cooling circuits, (1) liquid nitrogen cooling circuit operating at 80 K to minimize the radiation heat load on the magnets, and (2) liquid helium cooling circuit to cool magnets and cold mass support structure to 4.5 K. In this paper we describe (a) the leak testing of copper - SS joints, brazing joints, interconnecting joints of the superconducting magnets, and (b) the leak testing of the liquid nitrogen cooling circuit, comprising of the main supply header, the thermal shields, interconnecting pipes, main return header and electrical isolators. All these tests were carried out using both vacuum and sniffer methods. (author)

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.

Non-equilibrium thermodynamics, heat transport and thermal waves in laminar and turbulent superfluid helium

Science.gov (United States)

Mongiovì, Maria Stella; Jou, David; Sciacca, Michele

2018-01-01

This review paper puts together some results concerning non equilibrium thermodynamics and heat transport properties of superfluid He II. A one-fluid extended model of superfluid helium, which considers heat flux as an additional independent variable, is presented, its microscopic bases are analyzed, and compared with the well known two-fluid model. In laminar situations, the fundamental fields are density, velocity, absolute temperature, and heat flux. Such a theory is able to describe the thermomechanical phenomena, the propagation of two sounds in liquid helium, and of fourth sound in superleak. It also leads in a natural way to a two-fluid model on purely macroscopical grounds and allows a small amount of entropy associated with the superfluid component. Other important features of liquid He II arise in rotating situations and in superfluid turbulence, both characterized by the presence of quantized vortices (thin vortex lines whose circulation is restricted by a quantum condition). Such vortices have a deep influence on the transport properties of superfluid helium, as they increase very much its thermal resistance. Thus, heat flux influences the vortices which, in turn, modify the heat flux. The dynamics of vortex lines is the central topic in turbulent superfluid helium. The model is generalized to take into account the vortices in different cases of physical interest: rotating superfluids, counterflow superfluid turbulence, combined counterflow and rotation, and mass flow in addition to heat flow. To do this, the averaged vortex line density per unit volume L, is introduced and its dynamical equations are considered. Linear and non-linear evolution equations for L are written for homogeneous and inhomogeneous, isotropic and anisotropic situations. Several physical experiments are analyzed and the influence of vortices on the effective thermal conductivity of turbulent superfluid helium is found. Transitions from laminar to turbulent flows, from diffusive to

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

Study of a decaying helium plasma having a high neutral particle density; Etude d'un plasma d'helium, a forte densite de neutres, en regime de relaxation

Energy Technology Data Exchange (ETDEWEB)

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

1968-07-01

We have shown theoretically, in a high pressure, decaying helium plasma, the effect at low energy of inelastic collisions between neutral particles on the population densities of excited molecules and electron-ion recombination coefficient. The formalism of Bates (1962) has been used, taking into account simultaneously collisional mechanisms with electrons, collisional mechanisms with neutrals and radiative processes. The variation of the population densities and electron-ion recombination coefficient with respect to the pressure is given for different values of electron density and temperature. These theoretical results indicate an effect of pressure large enough to be measured and allow us to define the most favorable experimental conditions. (author) [French] L'effet des collisions inelastiques entre particules neutres dans un plasma d'helium, en regime de relaxation, a basse temperature electronique et forte densite de neutres, a ete mis en evidence, theoriquement, aussi bien dans le calcul des densites de population des molecules excitees que dans la determination du coefficient de recombinaison electron-ion. Nous avons utilise le formalisme de Bates (1962) en tenant compte simultanement des mecanismes collisionnels avec les electrons, des mecanismes collisionnels avec les neutres et des phenomenes radiatifs. La variation des densites de population et du coefficient de recombinaison electron-ion en fonction de la pression est donnee pour differentes valeurs de la densite electronique et de la temperature. Ces resultats theoriques laissent prevoir un effet de la pression suffisamment important pour qu'il puisse etre mesure et permettent de definir les conditions experimentales les plus favorables. (auteur)

A Nestin-cre transgenic mouse is insufficient for recombination in early embryonic neural progenitors

Directory of Open Access Journals (Sweden)

Huixuan Liang

2012-09-01

Nestin-cre transgenic mice have been widely used to direct recombination to neural stem cells (NSCs and intermediate neural progenitor cells (NPCs. Here we report that a readily utilized, and the only commercially available, Nestin-cre line is insufficient for directing recombination in early embryonic NSCs and NPCs. Analysis of recombination efficiency in multiple cre-dependent reporters and a genetic mosaic line revealed consistent temporal and spatial patterns of recombination in NSCs and NPCs. For comparison we utilized a knock-in Emx1cre line and found robust recombination in NSCs and NPCs in ventricular and subventricular zones of the cerebral cortices as early as embryonic day 12.5. In addition we found that the rate of Nestin-cre driven recombination only reaches sufficiently high levels in NSCs and NPCs during late embryonic and early postnatal periods. These findings are important when commercially available cre lines are considered for directing recombination to embryonic NSCs and NPCs.

Effect of recombinant adenovirus encoding human p53 tumor suppressor gene combined with radiation therapy on human lymphoma cells lines

International Nuclear Information System (INIS)

Yu Zeyang; Fan Wo; Li Dongqing; Zhu Ran; Wan Jianmei; Wang Yongqing; Wu Jinchang

2008-01-01

This paper analyzes the inhibitory effect and radiation sensitization of recombinant adenovirus encoding human p53 tumor suppressor gene (rAd-p53) on human lymphoma cell lines. Human lymphoma cell lines were treated with rAd-p53, radiation therapy and combined treatment, respectively. The cell growth inhibition was assessed by MTF. The cell cycle and apoptosis were detected by flow cytometry, and the p53 protein expression was detected by Western blotting. The results showed that extrinsic p53 gene have expressed to some degree, but not at high level. The role of inhibition and radiation sensitivity of rAd-p53 was not significant to human lymphoma cell lines. (authors)

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

Stabilization of burn conditions in an ITER FEAT like Tokamak with uncertainties in the helium ash confinement time

International Nuclear Information System (INIS)

Vitela, J.E.

2004-01-01

In this work we demonstrate using a two-temperature volume averaged 0-D model that robust stabilization, with regard the helium ash confinement time, of the burn conditions of a tokamak reactor with the ITER FEAT design parameters can be achieved using Radial Basis Neural Networks (RBNN). Alpha particle thermalization time delay is taken into account in this model. The control actions implemented by means of a RBNN, include the modulation of the D-T (deuterium and tritium) refueling rate, a neutral He-4 injection beam and auxiliary heating powers to ions and electrons; all of them constrained to lie within allowable range values. Here we assume that the tokamak follows the IPB98(y,2) scaling for the energy confinement time, while helium ash confinement time is assumed to be independently estimated on-line. The D-T and helium ash particle confinement times are assumed to keep a constant relationship at all times. An on-line noisy estimation of the helium ash confinement time due to measurements is simulated by corrupting it with pseudo Gaussian noise. (author)

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.)

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.)

Characterization of the binding of radioiodinated hybrid recombinant IFN-alpha A/D to murine and human lymphoid cell lines

International Nuclear Information System (INIS)

Faltynek, C.R.; Princler, G.L.; Schwabe, M.; Shata, M.T.; Lewis, G.K.; Kamin-Lewis, R.M.

1990-01-01

The hybrid recombinant human interferon (IFN) rIFN-alpha A/D was radioiodinated. Specific binding of [125I]rIFN-alpha A/D was observed with both human and murine cell lines. The binding of [125I]rIFN-alpha A/D to human Daudi cells had similar characteristics to the previously described binding of [125I]rIFN-alpha A or -alpha 2. The following lines of evidence demonstrated that [125I]rIFN-alpha A/D bound with high affinity to the same receptor on murine cells as murine IFN-alpha and -beta: (i) the binding of [125I]rIFN-alpha A/D to murine LBRM cells was inhibited to a similar extent by natural murine IFN-alpha, natural murine IFN-beta, and rIFN-A/D; (ii) the Kd (approximately 2 X 10(-10) M) obtained from both competition experiments and saturation binding experiments with [125I]rIFN-alpha A/D was comparable to the previously reported Kd for the binding of natural murine IFN-alpha and -beta to other murine cell lines; (iii) the size of the cross-linked [125I]rIFN-alpha A/D receptor complex formed on murine LBRM cells was similar to the previously reported cross-linked complex formed after binding radioiodinated natural murine IFN-beta to other murine cell lines. Due to the current lack of readily available recombinant murine IFN-alpha or -beta for radiolabeling and the previously demonstrated biological activity of rIFN-alpha A/D on murine cells, [125I]rIFN-alpha A/D should prove to be a useful reagent for further studies of murine IFN receptors

First-principles study of Frenkel pair recombination in tungsten

International Nuclear Information System (INIS)

Qin, Shi-Yao; Jin, Shuo; Li, Yu-Hao; Zhou, Hong-Bo; Zhang, Ying; Lu, Guang-Hong

2017-01-01

The recombination of one Frenkel pair in tungsten has been investigated through first-principles simulation. Two different recombination types have been identified: instantaneous and thermally activated. The small recombination barriers for thermally activated recombination cases indicate that recombination can occur easily with a slightly increased temperature. For both of the two recombination types, recombination occurs through the self-interstitial atom moving towards the vacancy. The recombination process can be direct or through replacement sequences, depending on the vertical distance between the vacancy and the 〈1 1 1〉 line of self-interstitial atom pair.

Analysis of recombinant Schistosoma mansoni antigen rSmp28 by on-line liquid chromatography-mass spectrometry combined with sodium dodecyl sulfate polyacrylamide gel electrophoresis

NARCIS (Netherlands)

Klarskov, K.; Roecklin, D.; Bouchon, B.; Sabatie, J.; Van Dorsselaer, A.; Bischoff, Rainer

1994-01-01

A recombinant Schistosoma mansoni antigen produced in Saccharomyces cerevisiae and purified by glutathione-Sepharose affinity chromatography was analyzed by tryptic peptide mapping using on-line reversed-phase high-performance liquid chromatography pneumatically assisted electrospray mass

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

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.

A summary of processes relevant for the particle balance of a cold plasma blanket contaminated with a small amount of helium

International Nuclear Information System (INIS)

Potters, J.H.H.M.; Goedheer, W.J.

1982-04-01

A summary is given of the atomic processes which are relevant for the ionization balance and for the transport in a plasma consisting of hydrogen with a small admixture of helium. Attention is paid mainly to processes in plasmas with temperatures below 100 eV and electron densities between 3x10 13 and 3x10 14 cm -3 conditions which prevail in a so-called cold plasma blanket. The species considered are electrons, protons, hydrogen atoms (ground state and excited), α-particles, He + -ions (ground state and excited), and helium atoms (ground state and excited). The discussed processes are charge exchange, ionization, recombination, (de-) excitation, and elastic scattering

Radio Recombination Line Surveys of the inner Galactic Plane: SIGGMA and GDIGS

Science.gov (United States)

Liu, Bin; Anderson, Loren Dean; Luisi, Matteo; Balser, Dana; Bania, Thomas; Wenger, Trey; Haffner, Lawrence Matthew; Minchin, Robert; Roshi, Anish; Churchwell, Edward; Terzian, Yervant; McIntyre, Travis; Lebron, Mayra; SIGGMA team, GDIGS team

2018-01-01

Ionized gas is one of the primary components of the interstellar medium (ISM) and plays a crucial role in star formation and galaxy evolution. Radio recombination lines (RRLs) can directly trace ionized gas in HII regions and warm ionized medium (WIM) without being affected by interstellar extinction. Single-dish telescopes like Arecibo Observatory and the Green Bank Telescope (GBT) are sensitive to low surface brightness emission, and are therefore powerful tools for the study of HII regions and the WIM. We report here on two large surveys of RRL emission: The Survey of Ionized Gas in the Galaxy, Made with the Arecibo telescope (SIGGMA) and the GBT Diffuse Ionized Gas Survey (GDIGS). These are the first large-scale fully-sampled RRL surveys, and together cover nearly the entire first quadrant of the Galactic plane at ~arcmin spatial resolution (l = -5 - 32 deg. for GDIGS and l = 32 - 70 deg. for SIGGMA). SIGGMA is performed with the Arecibo L-band Feed Array (ALFA) receiver, whose bandpass covers twelve hydrogen alpha lines from H163α to H174α. By stacking the α-lines and smoothing to 4 km/s velocity resolution, the final SIGGMA spectra have a mean rms level of ~0.65 mJy per beam. The GDIGS data were taken with the GBT C-band receiver and the VEGAS backend and include RRLs from H95α to H117α, and when stacked and smoothed to 5 km/s resolution achieve 1 mJy per beam rms. Here, we report on early analysis of the SIGGMA and GDIGS data, and present first scientific results.

Diagnostics of helium plasmas under special consideration of the continuous spectrum

International Nuclear Information System (INIS)

Einfeld, D.

1974-01-01

From measurements of the spectral beam density of the helium plasma in the region 290 nm to 650 nm, transition probabilities, Gaunt factors, line broadening parameters and deviations from the state of local thermodynamic equilibrium (L.T.E.) were determined and compared with theoretical data. Using the Gaunt factors experimentally secured in this work for the term n = 3, the electron density could be determined with an uncertainty of +-10% from the emission coefficients of the continuous spectrum. Assuming steady transition of the spectral emission coefficients over the series limit, a numerical method has been given according to which, amongst others, the Gaunt factors for the various series limits can be determined from the transition probabilities of these series. By determining the overpopulation factors of the ground states of the helium atom and the helium ion, a deviation from the L.T.E. state is experimentally detected and quantitatively described. (orig./LH) [de

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

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

EXTREMELY BROAD RADIO RECOMBINATION MASER LINES TOWARD THE HIGH-VELOCITY IONIZED JET IN CEPHEUS A HW2

International Nuclear Information System (INIS)

Jimenez-Serra, I.; Patel, N.; Martin-Pintado, J.; Baez-Rubio, A.; Thum, C.

2011-01-01

We present the first detection of the H40α, H34α, and H31α radio recombination lines (RRLs) at millimeter wavelengths toward the high-velocity ionized jet in the Cepheus A HW2 star-forming region. From our single-dish and interferometric observations, we find that the measured RRLs show extremely broad asymmetric line profiles with zero-intensity line widths of ∼1100 km s -1 . From the line widths, we estimate a terminal velocity for the ionized gas in the jet of ≥500 km s -1 , consistent with that obtained from the proper motions of the HW2 radio jet. The total integrated line-to-continuum flux ratios of the H40α, H34α, and H31α lines are 43, 229, and 280 km s -1 , clearly deviating from LTE predictions. These ratios are very similar to those observed for the RRL masers toward MWC349A, suggesting that the intensities of the RRLs toward HW2 are affected by maser emission. Our radiative transfer modeling of the RRLs shows that their asymmetric profiles could be explained by maser emission arising from a bi-conical radio jet with a semi-opening angle of 18 deg., electron density distribution varying as r -2.11 , and turbulent and expanding wind velocities of 60 and 500 km s -1 .

Numerical and experimental investigation of laser induced plasma spectrum of aluminum in the presence of a noble gas

International Nuclear Information System (INIS)

Rezaei, Fatemeh; Tavassoli, Seyed Hassan

2012-01-01

Laser-induced plasma emission of an aluminum target in helium gas at 1 atm pressure is numerically and experimentally investigated. A laser pulse at wavelength of 266 nm and pulse duration of 10 ns has been considered. Laser ablation is calculated by a one dimensional model based on thermal evaporation mechanism. Spatial and temporal parameters of plasma expansion are determined by using hydrodynamic equations. Three kinds of plasma emission, including Bremsstrahlung, recombination and spectral emissions are considered for modeling the spectrum. Strong lines of aluminum and helium in wavelength interval of 200 to 450 nm are selected. Aluminum spectrum in UV range is depicted and compared with other spectral ranges. Temporal and spatial evolution of plasma emission up to 200 ns after the laser irradiation is studied. The effect of laser energy on the plasma spectrum is studied. An experimental set-up is arranged to compare numerical calculations with experimental results. Experimental and numerical results illustrate that helium line widths and peak intensities become narrower and weaker with time, respectively. Spatial distribution of spectrum shows that for closer distance to the sample surface, an intense continuous emission is observed, while at the farther distance, continuous emission decreases and spectral lines become sharper. A good coincidence is observed between experimental and numerical results. - Highlights: ► Aluminum plasma emission in helium is numerically and experimentally studied. ► Spectral, Bremsstrahlung and recombination emissions in spectrum are calculated. ► All strong lines of aluminum and helium are chosen for spectrum simulation. ► Line widths and peak intensities at later times become narrower and weaker. ► At specific optimum position, the maximum of signal peaks is acquired.

Functional Coding Variation in Recombinant Inbred Mouse Lines Reveals Novel Serotonin Transporter-Associated Phenotypes

Energy Technology Data Exchange (ETDEWEB)

Carneiro, Ana [Vanderbilt University; Airey, David [University of Tennessee Health Science Center, Memphis; Thompson, Brent [Vanderbilt University; Zhu, C [Vanderbilt University; Rinchik, Eugene M [ORNL; Lu, Lu [University of Tennessee Health Science Center, Memphis; Chesler, Elissa J [ORNL; Erikson, Keith [University of North Carolina; Blakely, Randy [Vanderbilt University

2009-01-01

The human serotonin (5-hydroxytryptamine, 5-HT) transporter (hSERT, SLC6A4) figures prominently in the etiology or treatment of many prevalent neurobehavioral disorders including anxiety, alcoholism, depression, autism and obsessive-compulsive disorder (OCD). Here we utilize naturally occurring polymorphisms in recombinant inbred (RI) lines to identify novel phenotypes associated with altered SERT function. The widely used mouse strain C57BL/6J, harbors a SERT haplotype defined by two nonsynonymous coding variants (Gly39 and Lys152 (GK)). At these positions, many other mouse lines, including DBA/2J, encode Glu39 and Arg152 (ER haplotype), assignments found also in hSERT. Synaptosomal 5-HT transport studies revealed reduced uptake associated with the GK variant. Heterologous expression studies confirmed a reduced SERT turnover rate for the GK variant. Experimental and in silico approaches using RI lines (C57Bl/6J X DBA/2J=BXD) identifies multiple anatomical, biochemical and behavioral phenotypes specifically impacted by GK/ER variation. Among our findings are multiple traits associated with anxiety and alcohol consumption, as well as of the control of dopamine (DA) signaling. Further bioinformatic analysis of BXD phenotypes, combined with biochemical evaluation of SERT knockout mice, nominates SERT-dependent 5-HT signaling as a major determinant of midbrain iron homeostasis that, in turn, dictates ironregulated DA phenotypes. Our studies provide a novel example of the power of coordinated in vitro, in vivo and in silico approaches using murine RI lines to elucidate and quantify the system-level impact of gene variation.

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.

End of the line to build a circle

CERN Multimedia

2006-01-01

The installation of the cryogenic distribution line in the LHC tunnel is finally finished! All the sectors have undergone pressure and helium leak tests at room temperature, and one complete sector was cold tested in cryogenic conditions. Some of the QRL team in UJ22 of the LHC tunnel, where the last sector of the cryogenic distribution line was installed.It must have been a joyous moment in UJ22 of the LHC tunnel (near Point 2, Saint Genis Pouilly) on 19 October. This was where the last external weld of the cryogenic distribution line, also known as QRL, was made, thus completing the full distribution ring. The QRL is a circle built in 8 sectors, each approximately 3 km in length. It will circulate helium in liquid and gas phases, at different temperatures and pressures, to provide the cryogenic conditions for the superconducting magnets in the LHC tunnel. The last sector installed (sector 1-2) passed the pressure and helium leak tests at room temperature on 28 October. As part of the warm test, each sector...

Particle and energy transport studies on TFTR and implications for helium ash in future fusion devices

International Nuclear Information System (INIS)

Synakowski, E.J.; Efthimion, P.C.; Rewoldt, G.; Stratton, B.C.; Tang, W.M.; Bell, R.E.; Grek, B.; Hulse, R.A.; Johnson, D.W.; Hill, K.W.; Mansfield, D.K.; McCune, D.; Mikkelsen, D.R.; Park, H.K.; Ramsey, A.T.; Scott, S.D.; Taylor, G.; Timberlake, J.; Zarnstorff, M.C.

1992-01-01

Particle and energy transport in tokamak plasmas have long been subjects of vigorous investigation. Present-day measurement techniques permit radially resolved studies of the transport of electron perturbations, low- and high-Z impurities, and energy. In addition, developments in transport theory provide tools that can be brought to bear on transport issues. Here, we examine local particle transport measurements of electrons, fully-stripped thermal helium, and helium-like iron in balanced-injection L-mode and enhanced confinement deuterium plasmas on TFTR of the same plasma current, toroidal field, and auxiliary heating power. He 2+ and Fe 24+ transport has been studied with charge exchange recombination spectroscopy, while electron transport has been studied by analyzing the perturbed electron flux following the same helium puff used for the He 2+ studies. By examining the electron and He 2+ responses following the same gas puff in the same plasmas, an unambiguous comparison of the transport of the two species has been made. The local energy transport has been examined with power balance analysis, allowing for comparisons to the local thermal fluxes. Some particle and energy transport results from the Supershot have been compared to a transport model based on a quasilinear picture of electrostatic toroidal drift-type microinstabilities. Finally, implications for future fusion reactors of the observed correlation between thermal transport and helium particle transport is discussed

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.

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

Binary and ternary recombination of para-H3(+) and ortho-H3(+) with electrons: state selective study at 77-200 K.

Science.gov (United States)

Dohnal, Petr; Hejduk, Michal; Varju, Jozef; Rubovič, Peter; Roučka, Štěpán; Kotrík, Tomáš; Plašil, Radek; Glosík, Juraj; Johnsen, Rainer

2012-06-28

Measurements in H(3)(+) afterglow plasmas with spectroscopically determined relative abundances of H(3)(+) ions in the para-nuclear and ortho-nuclear spin states provide clear evidence that at low temperatures (77-200 K) para-H(3)(+) ions recombine significantly faster with electrons than ions in the ortho state, in agreement with a recent theoretical prediction. The cavity ring-down absorption spectroscopy used here provides an in situ determination of the para/ortho abundance ratio and yields additional information on the translational and rotational temperatures of the recombining ions. The results show that H(3)(+) recombination with electrons occurs by both binary recombination and third-body (helium) assisted recombination, and that both the two-body and three-body rate coefficients depend on the nuclear spin states. Electron-stabilized (collisional-radiative) recombination appears to make only a small contribution.

Binary and ternary recombination of para-H3+ and ortho-H3+ with electrons: State selective study at 77-200 K

Science.gov (United States)

Dohnal, Petr; Hejduk, Michal; Varju, Jozef; Rubovič, Peter; Roučka, Štěpán; Kotrík, Tomáš; Plašil, Radek; Glosík, Juraj; Johnsen, Rainer

2012-06-01

Measurements in H_3^+ afterglow plasmas with spectroscopically determined relative abundances of H_3^+ ions in the para-nuclear and ortho-nuclear spin states provide clear evidence that at low temperatures (77-200 K) para-H_3^+ ions recombine significantly faster with electrons than ions in the ortho state, in agreement with a recent theoretical prediction. The cavity ring-down absorption spectroscopy used here provides an in situ determination of the para/ortho abundance ratio and yields additional information on the translational and rotational temperatures of the recombining ions. The results show that H_3^+ recombination with electrons occurs by both binary recombination and third-body (helium) assisted recombination, and that both the two-body and three-body rate coefficients depend on the nuclear spin states. Electron-stabilized (collisional-radiative) recombination appears to make only a small contribution.

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

NON-EQUILIBRIUM HELIUM IONIZATION IN AN MHD SIMULATION OF THE SOLAR ATMOSPHERE

International Nuclear Information System (INIS)

Golding, Thomas Peter; Carlsson, Mats; Leenaarts, Jorrit

2016-01-01

The ionization state of the gas in the dynamic solar chromosphere can depart strongly from the instantaneous statistical equilibrium commonly assumed in numerical modeling. We improve on earlier simulations of the solar atmosphere that only included non-equilibrium hydrogen ionization by performing a 2D radiation-magnetohydrodynamics simulation featuring non-equilibrium ionization of both hydrogen and helium. The simulation includes the effect of hydrogen Lyα and the EUV radiation from the corona on the ionization and heating of the atmosphere. Details on code implementation are given. We obtain helium ion fractions that are far from their equilibrium values. Comparison with models with local thermodynamic equilibrium (LTE) ionization shows that non-equilibrium helium ionization leads to higher temperatures in wavefronts and lower temperatures in the gas between shocks. Assuming LTE ionization results in a thermostat-like behavior with matter accumulating around the temperatures where the LTE ionization fractions change rapidly. Comparison of DEM curves computed from our models shows that non-equilibrium ionization leads to more radiating material in the temperature range 11–18 kK, compared to models with LTE helium ionization. We conclude that non-equilibrium helium ionization is important for the dynamics and thermal structure of the upper chromosphere and transition region. It might also help resolve the problem that intensities of chromospheric lines computed from current models are smaller than those observed

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

Expression of recombinant Antibodies

Directory of Open Access Journals (Sweden)

André eFrenzel

2013-07-01

Full Text Available Recombinant antibodies are highly specific detection probes in research, diagnostics and have emerged over the last two decades as the fastest growing class of therapeutic proteins. Antibody generation has been dramatically accelerated by in vitro selection systems, particularly phage display. An increasing variety of recombinant production systems have been developed, ranging from Gram-negative and positive bacteria, yeasts and filamentous fungi, insect cell lines, mammalian cells to transgenic plants and animals. Currently, almost all therapeutic antibodies are still produced in mammalian cell lines in order to reduce the risk of immunogenicity due to altered, non-human glycosylation patterns. However, recent developments of glycosylation-engineered yeast, insect cell lines and transgenic plants are promising to obtain antibodies with human-like post-translational modifications. Furthermore, smaller antibody fragments including bispecific antibodies without any glycosylation are successfully produced in bacteria and have advanced to clinical testing. The first therapeutic antibody products from a non-mammalian source can be expected in coming next years. In this review, we focus on current antibody production systems including their usability for different applications.

The Genetic Architecture of Natural Variation in Recombination Rate in Drosophila melanogaster.

Science.gov (United States)

Hunter, Chad M; Huang, Wen; Mackay, Trudy F C; Singh, Nadia D

2016-04-01

Meiotic recombination ensures proper chromosome segregation in many sexually reproducing organisms. Despite this crucial function, rates of recombination are highly variable within and between taxa, and the genetic basis of this variation remains poorly understood. Here, we exploit natural variation in the inbred, sequenced lines of the Drosophila melanogaster Genetic Reference Panel (DGRP) to map genetic variants affecting recombination rate. We used a two-step crossing scheme and visible markers to measure rates of recombination in a 33 cM interval on the X chromosome and in a 20.4 cM interval on chromosome 3R for 205 DGRP lines. Though we cannot exclude that some biases exist due to viability effects associated with the visible markers used in this study, we find ~2-fold variation in recombination rate among lines. Interestingly, we further find that recombination rates are uncorrelated between the two chromosomal intervals. We performed a genome-wide association study to identify genetic variants associated with recombination rate in each of the two intervals surveyed. We refined our list of candidate variants and genes associated with recombination rate variation and selected twenty genes for functional assessment. We present strong evidence that five genes are likely to contribute to natural variation in recombination rate in D. melanogaster; these genes lie outside the canonical meiotic recombination pathway. We also find a weak effect of Wolbachia infection on recombination rate and we confirm the interchromosomal effect. Our results highlight the magnitude of population variation in recombination rate present in D. melanogaster and implicate new genetic factors mediating natural variation in this quantitative trait.

Sustained productivity in recombinant Chinese Hamster Ovary (CHO) cell lines: proteome analysis of the molecular basis for a process-related phenotype

LENUS (Irish Health Repository)

Meleady, Paula

2011-07-24

Abstract Background The ability of mammalian cell lines to sustain cell specific productivity (Qp) over the full duration of bioprocess culture is a highly desirable phenotype, but the molecular basis for sustainable productivity has not been previously investigated in detail. In order to identify proteins that may be associated with a sustained productivity phenotype, we have conducted a proteomic profiling analysis of two matched pairs of monoclonal antibody-producing Chinese hamster ovary (CHO) cell lines that differ in their ability to sustain productivity over a 10 day fed-batch culture. Results Proteomic profiling of inherent differences between the two sets of comparators using 2D-DIGE (Difference Gel Electrophoresis) and LC-MS\\/MS resulted in the identification of 89 distinct differentially expressed proteins. Overlap comparisons between the two sets of cell line pairs identified 12 proteins (AKRIB8, ANXA1, ANXA4, EIF3I, G6PD, HSPA8, HSP90B1, HSPD1, NUDC, PGAM1, RUVBL1 and CNN3) that were differentially expressed in the same direction. Conclusion These proteins may have an important role in sustaining high productivity of recombinant protein over the duration of a fed-batch bioprocess culture. It is possible that many of these proteins could be useful for future approaches to successfully manipulate or engineer CHO cells in order to sustain productivity of recombinant protein.

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

Radiative and three-body recombination in the Alcator C-Mod divertor

International Nuclear Information System (INIS)

Lumma, D.; Terry, J.L.; Lipschultz, B.

1997-01-01

Significant recombination of the majority ion species has been observed in the divertor region of Alcator C-Mod [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)] under detached conditions. This determination is made by analysis of the visible spectrum from the divertor, in particular the Balmer series line emission and the observed recombination continuum, including an apparent recombination edge at ∼375 nm. The analysis shows that the electron temperature in the recombining plasma is 0.8 endash 1.5 eV. The measured volume recombination rate is comparable to the rate of ion collection at the divertor plates. The dominant recombination mechanism is three-body recombination into excited states (e+e+D + Right-arrow D 0 +e), although radiative recombination (e+D + Right-arrow D 0 +hν) contributes ∼5% to the total rate. Analysis of the Balmer series line intensities (from n upper =3 through 10) shows that the upper levels of these transitions are populated primarily by recombination. Thus the brightnesses of the Balmer series (and Lyman series) are directly related to the recombination rate. copyright 1997 American Institute of Physics

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
...

Applicability of the dielectric barrier discharge for helium ash measurements in the divertor region

Directory of Open Access Journals (Sweden)

Książek Ireneusz

2016-06-01

Full Text Available Controlled fusion based on the magnetic confinement of the plasma is one of the main aims of the Euro-fusion programme. In the fusion device, the hydrogen isotopes, in nuclear reactions, will produce helium nuclei. The products, as the ash, will be removed from the plasma in the region of the so-called divertor. Controlling the helium to hydrogen ratio in this ‘exhaust gas’ will provide information about the efficiency of the fusion process as well as of the efficiency of the helium removal system. One of the methods to perform this task is to study the properties of the discharge conducted in such exhaust gas. In this paper, the applicability of the dielectric barrier discharge (DBD is studied. This preliminary experiment shows a great potential in applicability of this kind of discharge. The optical as well as pulse-height spectra were studied, both revealing very promising properties. In the optical spectrum, one can observe well separated hydrogen and helium spectral lines, with intensities of the same order of magnitude. Moreover, in the registered spectral region, the molecular spectra are negligible. The pulse-height spectra reveal very distinct shape in helium and hydrogen. Checking of this spectrum could provide parallel (redundant information about the partial pressure of helium in the magnetic confinement fusion (MCF device exhaust gas.

A NEW RADIO RECOMBINATION LINE MASER OBJECT TOWARD THE MonR2 H II REGION

Energy Technology Data Exchange (ETDEWEB)

Jimenez-Serra, I.; Zhang, Q.; Dierickx, M.; Patel, N. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Baez-Rubio, A.; Rivilla, V. M.; Martin-Pintado, J., E-mail: ijimenez-serra@cfa.harvard.edu, E-mail: qzhang@cfa.harvard.edu, E-mail: mdierickx@cfa.harvard.edu, E-mail: npatel@cfa.harvard.edu, E-mail: ryvendel@gmail.com, E-mail: jmartin@cab.inta-csic.es, E-mail: baezra@cab.inta-csic.es [Centro de Astrobiologia (CSIC/INTA), Ctra. de Torrejon a Ajalvir km 4, E-28850 Torrejon de Ardoz, Madrid (Spain)

2013-02-10

We report the detection of a new radio recombination line (RRL) maser object toward the IRS2 source in the MonR2 ultracompact H II region. The continuum emission at 1.3 mm and 0.85 mm and the H30{alpha} and H26{alpha} lines were observed with the Submillimeter Array (SMA) at angular resolutions of {approx}0.''5-3''. The SMA observations show that the MonR2-IRS2 source is very compact and remains unresolved at spatial scales {<=}400 AU. Its continuum power spectrum at millimeter wavelengths is almost flat ({alpha} = -0.16, with S{sub {nu}}{proportional_to}{nu}{sup {alpha}}), indicating that this source is dominated by optically thin free-free emission. The H30{alpha} and H26{alpha} RRL emission is also compact and peaks toward the position of the MonR2-IRS2 source. The measured RRL profiles are double peaked with the H26{alpha} line showing a clear asymmetry in its spectrum. Since the derived line-to-continuum flux ratios ({approx}80 and 180 km s{sup -1} for H30{alpha} and H26{alpha}, respectively) exceed the LTE predictions, the RRLs toward MonR2-IRS2 are affected by maser amplification. The amplification factors are, however, smaller than those found toward the emission-line star MWC349A, indicating that MonR2-IRS2 is a weakly amplified maser. Radiative transfer modeling of the RRL emission toward this source shows that the RRL masers arise from a dense and collimated jet embedded in a cylindrical ionized wind, oriented nearly along the direction of the line of sight. High-angular resolution observations at submillimeter wavelengths are needed to unveil weakly amplified RRL masers in very young massive stars.

Impact of process parameters and design options on heat leaks of straight cryogenic distribution lines

CERN Document Server

Duda, Pawel; Chorowski, Maciej Pawel; Polinski, J

2017-01-01

The Future Circular Collider (FCC) accelerator will require a helium distribution system that will exceed the presently exploited transfer lines by almost 1 order of magnitude. The helium transfer line will contain five process pipes protected against heat leaks by a common thermal shield. The design pressure of the FCC process pipe with supercritical helium will be equal to 5.0 MPa, significantly exceeding the 2.0 MPa value in the present, state-of–art transfer lines. The increase of the design pressure requires construction changes to be introduced to the support system, the vacuum barriers and the compensation bellows. This will influence heat flows to the helium. The paper analyses the impact of the increased design pressure on the heat flow. The paper also offers a discussion of the design modifications to the compensation system, including the replacement of stainless steel with Invar—aimed at mitigating the pressure increase.

Superconducting cable cooling system by helium gas at two pressures

International Nuclear Information System (INIS)

Dean, J.W.

1977-01-01

Thermally contacting, oppositely streaming, cryogenic fluid streams in the same enclosure in a closed cycle changes the fluid from a cool high pressure helium gas to a cooler reduced pressure helium gas in an expander so as to be at different temperature ranges and pressures respectively in go and return legs that are in thermal contact with each other and in thermal contact with a longitudinally extending superconducting transmission line enclosed in the same cable enclosure that insulates the line from the ambient at a temperature T 1 . By first circulating the fluid from a refrigerator at one end of the line as a cool gas at a temperature range T 2 to T 3 in the go leg, then circulating the gas through an expander at the other end of the line where the gas becomes a cooler gas at a reduced pressure and at a reduced temperature T 4 and finally by circulating the cooler gas back again to the refrigerator in a return leg at a temperature range T 4 to T 5 , while in thermal contact with the gas in the go leg, and in the same enclosure therewith for compression into a higher pressure gas at T 2 in a closed cycle, where T 2 greater than T 3 and T 5 greater than T 4 , the fluid leaves the enclosure in the go leg as a gas at its coldest point in the go leg, and the temperature distribution is such that the line temperature decreases along its length from the refrigerator due to the cooling from the gas in the return leg

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

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

Precision Measurement of the Energies and Line Shapes of Antiprotonic Lyman and Balmer Transitions From Hydrogen and Helium Isotopes

CERN Multimedia

2002-01-01

% PS207 \\\\ \\\\ For the study of the antiproton-proton and antiproton-nuclear spin-spin and spin-orbital interaction at threshold a high resolution measurement is proposed of the line shapes and energy shifts of antiprotonic K$\\alpha$ and L$\\alpha$ transitions of hydrogen and helium isotopes. The intense LEAR beam, stopped in the cyclotron trap at low gas pressure, provides a unique~X-ray~source with sufficient brightness. Charge coupled devices with their excellent background rejection and energy resolution allow a precise determination of the strong shifts and widths of the 1s hyperfine states of protonium, in addition the detection of the $\\bar{p}$D K$\\alpha$ transition should be possible. A focussing crystal spectrometer with a resolution $\\Delta$E/E of about l0$ ^- ^{4} $, which is superior in the accuracy of the energy determination by two orders of magnitude as compared to the present detection methods, will be used to measure the energies of the L$\\alpha$ transitions. This permits a first direct measure...

X-ray emission lines from photoionized plasmas

International Nuclear Information System (INIS)

Liedahl, D.A.

1992-11-01

Plasma emission codes have become a standard tool for the analysis of spectroscopic data from cosmic X-ray sources. However, the assumption of collisional equilibrium, typically invoked in these codes, renders them inapplicable to many important astrophysical situations, particularly those involving X-ray photoionized nebulae, which are likely to exist in the circumsource environments of compact X-ray sources. X-ray line production in a photoionized plasma is primarily the result of radiative cascades following recombination. Through the development of atomic models of several highly-charged ions, this work extends the range of applicability of discrete spectral models to plasmas dominated by recombination. Assuming that ambient plasma conditions lie in the temperature range 10 5 --10 6 K and the density range 10 11 --10 16 cm -3 , X-ray line spectra are calculated over the wavelength range 5--45 angstrom using the HULLAC atomic physics package. Most of the work focuses on the Fe L-shell ions. Line ratios of the form (3s-2p)/(3d-2p) are shown to characterize the principal mode of line excitation, thereby providing a simple signature of photoionization. At electron densities exceeding 10 12 cm -3 , metastable state populations in the ground configurations approach their LTE value, resulting in the enrichment of the Fe L-shell recombination spectrum and a set of density-sensitive X-ray line ratios. Radiative recombination continua and emission lines produced selectively by Δn = 0 dielectronic recombination are shown to provide two classes of temperature diagnostics. Because of the extreme overionization, the recombination continua are expected to be narrow (ΔE/E much-lt 1), with ΔE = kT. Dielectronic recombination selectively drives radiative transitions that originate on states with vacancies in the 2s subshell, states that are inaccessible under pure RR population kinetics

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)

The Genetic Architecture of Natural Variation in Recombination Rate in Drosophila melanogaster.

Directory of Open Access Journals (Sweden)

Chad M Hunter

2016-04-01

Full Text Available Meiotic recombination ensures proper chromosome segregation in many sexually reproducing organisms. Despite this crucial function, rates of recombination are highly variable within and between taxa, and the genetic basis of this variation remains poorly understood. Here, we exploit natural variation in the inbred, sequenced lines of the Drosophila melanogaster Genetic Reference Panel (DGRP to map genetic variants affecting recombination rate. We used a two-step crossing scheme and visible markers to measure rates of recombination in a 33 cM interval on the X chromosome and in a 20.4 cM interval on chromosome 3R for 205 DGRP lines. Though we cannot exclude that some biases exist due to viability effects associated with the visible markers used in this study, we find ~2-fold variation in recombination rate among lines. Interestingly, we further find that recombination rates are uncorrelated between the two chromosomal intervals. We performed a genome-wide association study to identify genetic variants associated with recombination rate in each of the two intervals surveyed. We refined our list of candidate variants and genes associated with recombination rate variation and selected twenty genes for functional assessment. We present strong evidence that five genes are likely to contribute to natural variation in recombination rate in D. melanogaster; these genes lie outside the canonical meiotic recombination pathway. We also find a weak effect of Wolbachia infection on recombination rate and we confirm the interchromosomal effect. Our results highlight the magnitude of population variation in recombination rate present in D. melanogaster and implicate new genetic factors mediating natural variation in this quantitative trait.

Contrasting characteristics of sub-microsecond pulsed atmospheric air and atmospheric pressure helium-oxygen glow discharges

International Nuclear Information System (INIS)

Walsh, J L; Liu, D X; Iza, F; Kong, M G; Rong, M Z

2010-01-01

Glow discharges in air are often considered to be the ultimate low-temperature atmospheric pressure plasmas for numerous chamber-free applications. This is due to the ubiquitous presence of air and the perceived abundance of reactive oxygen and nitrogen species in air plasmas. In this paper, sub-microsecond pulsed atmospheric air plasmas are shown to produce a low concentration of excited oxygen atoms but an abundance of excited nitrogen species, UV photons and ozone molecules. This contrasts sharply with the efficient production of excited oxygen atoms in comparable helium-oxygen discharges. Relevant reaction chemistry analysed with a global model suggests that collisional excitation of O 2 by helium metastables is significantly more efficient than electron dissociative excitation of O 2 , electron excitation of O and ion-ion recombination. These results suggest different practical uses of the two oxygen-containing atmospheric discharges, with air plasmas being well suited for nitrogen and UV based chemistry and He-O 2 plasmas for excited atomic oxygen based chemistry. (fast track communication)

Numerical and experimental investigation of laser induced plasma spectrum of aluminum in the presence of a noble gas

Energy Technology Data Exchange (ETDEWEB)

Rezaei, Fatemeh, E-mail: f_rezaei@sbu.ac.ir; Tavassoli, Seyed Hassan

2012-12-01

Laser-induced plasma emission of an aluminum target in helium gas at 1 atm pressure is numerically and experimentally investigated. A laser pulse at wavelength of 266 nm and pulse duration of 10 ns has been considered. Laser ablation is calculated by a one dimensional model based on thermal evaporation mechanism. Spatial and temporal parameters of plasma expansion are determined by using hydrodynamic equations. Three kinds of plasma emission, including Bremsstrahlung, recombination and spectral emissions are considered for modeling the spectrum. Strong lines of aluminum and helium in wavelength interval of 200 to 450 nm are selected. Aluminum spectrum in UV range is depicted and compared with other spectral ranges. Temporal and spatial evolution of plasma emission up to 200 ns after the laser irradiation is studied. The effect of laser energy on the plasma spectrum is studied. An experimental set-up is arranged to compare numerical calculations with experimental results. Experimental and numerical results illustrate that helium line widths and peak intensities become narrower and weaker with time, respectively. Spatial distribution of spectrum shows that for closer distance to the sample surface, an intense continuous emission is observed, while at the farther distance, continuous emission decreases and spectral lines become sharper. A good coincidence is observed between experimental and numerical results. - Highlights: Black-Right-Pointing-Pointer Aluminum plasma emission in helium is numerically and experimentally studied. Black-Right-Pointing-Pointer Spectral, Bremsstrahlung and recombination emissions in spectrum are calculated. Black-Right-Pointing-Pointer All strong lines of aluminum and helium are chosen for spectrum simulation. Black-Right-Pointing-Pointer Line widths and peak intensities at later times become narrower and weaker. Black-Right-Pointing-Pointer At specific optimum position, the maximum of signal peaks is acquired.

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

Impact of process parameters and design options on heat leaks of straight cryogenic distribution lines

Directory of Open Access Journals (Sweden)

P. Duda

2017-03-01

Full Text Available The Future Circular Collider (FCC accelerator will require a helium distribution system that will exceed the presently exploited transfer lines by almost 1 order of magnitude. The helium transfer line will contain five process pipes protected against heat leaks by a common thermal shield. The design pressure of the FCC process pipe with supercritical helium will be equal to 5.0 MPa, significantly exceeding the 2.0 MPa value in the present, state-of–art transfer lines. The increase of the design pressure requires construction changes to be introduced to the support system, the vacuum barriers and the compensation bellows. This will influence heat flows to the helium. The paper analyses the impact of the increased design pressure on the heat flow. The paper also offers a discussion of the design modifications to the compensation system, including the replacement of stainless steel with Invar®—aimed at mitigating the pressure increase.

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

Primordial helium abundance determination using sulphur as metallicity tracer

Science.gov (United States)

Fernández, Vital; Terlevich, Elena; Díaz, Angeles I.; Terlevich, Roberto; Rosales-Ortega, F. F.

2018-05-01

The primordial helium abundance YP is calculated using sulphur as metallicity tracer in the classical methodology (with YP as an extrapolation of Y to zero metals). The calculated value, YP, S = 0.244 ± 0.006, is in good agreement with the estimate from the Planck experiment, as well as, determinations in the literature using oxygen as the metallicity tracer. The chemical analysis includes the sustraction of the nebular continuum and of the stellar continuum computed from simple stellar population synthesis grids. The S+2 content is measured from the near infrared [SIII]λλ9069Å, 9532Å lines, while an ICF(S3 +) is proposed based on the Ar3 +/Ar2 + fraction. Finally, we apply a multivariable linear regression using simultaneously oxygen, nitrogen and sulphur abundances for the same sample to determine the primordial helium abundance resulting in YP - O, N, S = 0.245 ± 0.007.

Evaluation of software sensors for on-line estimation of culture conditions in an Escherichia coli cultivation expressing a recombinant protein.

Science.gov (United States)

Warth, Benedikt; Rajkai, György; Mandenius, Carl-Fredrik

2010-05-03

Software sensors for monitoring and on-line estimation of critical bioprocess variables have mainly been used with standard bioreactor sensors, such as electrodes and gas analyzers, where algorithms in the software model have generated the desired state variables. In this article we propose that other on-line instruments, such as NIR probes and on-line HPLC, should be used to make more reliable and flexible software sensors. Five software sensor architectures were compared and evaluated: (1) biomass concentration from an on-line NIR probe, (2) biomass concentration from titrant addition, (3) specific growth rate from titrant addition, (4) specific growth rate from the NIR probe, and (5) specific substrate uptake rate and by-product rate from on-line HPLC and NIR probe signals. The software sensors were demonstrated on an Escherichia coli cultivation expressing a recombinant protein, green fluorescent protein (GFP), but the results could be extrapolated to other production organisms and product proteins. We conclude that well-maintained on-line instrumentation (hardware sensors) can increase the potential of software sensors. This would also strongly support the intentions with process analytical technology and quality-by-design concepts. 2010 Elsevier B.V. All rights reserved.

(Anti)hydrogen recombination studies in a nested Penning trap

International Nuclear Information System (INIS)

Quint, W.; Kaiser, R.; Hall, D.; Gabrielse, G.

1993-01-01

Extremely cold antiprotons, stored in Penning trap at 4 K, open the way toward the production and study of cold antihydrogen. We have begun experimentally investigating the possibility to recombine cold positrons and antiprotons within nested Penning traps. Trap potentials are adjusted to allow cold trapped protons (and positive helium ions) to pass through cold trapped electrons. Electrons, protons and ions are counted by ejecting them to a cold channel plate and by nondestructive radiofrequency techniques. The effect of the space charge of one trapped species upon another trapped species passing through is clearly observed. (orig.)

Molecular requirements for radiation-activated recombination

International Nuclear Information System (INIS)

Stevens, Craig W.; Zeng Ming; Stamato, Thomas; Cerniglia, George

1997-01-01

Purpose/Objective: The major stumbling block to successful gene therapy today is poor gene transfer. We hypothesized that ionizing radiation might activate cellular recombination, and so improve stable gene transfer. We further hypothesized that known DNA-damage-repair proteins might also be important in radiation-activated recombination. Materials and Methods: The effect of irradiation on stable gene transfer efficiency was determined in human (A549 and 39F) and rodent (NIH/3T3) cell lines. Continuous low dose rate and multiple radiation fractions were also tested. Nuclear extracts were made and the effect of irradiation on inter-plasmid recombination/ligation determined. Multiple DNA damage-repair deficient cell lines were tested for radiation-activated recombination. Results: A significant radiation dose-dependent improvement in stable plasmid transfection (by as much as 1300 fold) is demonstrated in neoplastic and primary cells. An improvement in transient plasmid transfection is also seen, with as much as 85% of cells transiently expressing b-galactosidase (20-50 fold improvement). Stable transfection is only improved for linearized or nicked plasmids. Cells have improved gene transfer for at least 96 hours after irradiation. Both fractionated and continuous low dose rate irradiation are effective at improving stable gene transfer in mammalian cells, thus making relatively high radiation dose delivery clinically feasible. Inter-plasmid recombination is radiation dose dependent in nuclear extract assays, and the type of overhang (3', 5' or blunt end) significantly affects recombination efficiency and the type of product. The most common end-joining activity involves filling-in of the overhang followed by blunt end ligation. Adenovirus is a linear, double stranded DNA virus. We demonstrate that adenoviral infection efficiency is increased by irradiation. The duration of transgene expression is lengthened because the virus integrates with high efficiency (∼10

Phenomena of non-thermal electrons from the X-ray imaging crystal spectrometer on J-TEXT tokamak

International Nuclear Information System (INIS)

Yan, W.; Chen, Z.Y.; Jin, W.; Huang, D.W.; Lee, S.G.; Shi, Y.J.; Tong, R.H.; Wang, S.Y.; Wei, Y.N.; Ma, T.K.; Zhuang, G.

2016-01-01

Highlights: • Some lines from X-ray imaging crystal spectrometer (XICS) can be enhanced by non-thermal electrons, such as q, r satellite lines and z lines. • Analyze the non-thermal phenomena can reduce the error of electron temperature deduced from the intensity ratio of different lines of the He-like argon spectra from XICS. • XICS can be a tool to measure the non-thermal phenomena from these enhanced lines. - Abstract: A high spectra resolution X-ray imaging crystal spectrometer has been implemented on J-TEXT Tokamak for the measurements of K_α spectra of helium-like argon and its satellite lines. The wavelength range of K_α spectra of helium-like argon is from 3.9494 Å to 3.9944 Å that includes the resonance line w, intercombination lines x and y, forbidden line z and numerous satellite lines, referenced using standard Gabriel notation. In low-density discharge, the intensity of q, r satellite lines and z lines can be significantly enhanced by non-thermal electrons. Non-thermal electrons are produced due to the low plasma density. The high hard X-ray flux from NaI detector and significant downshift electron cyclotron emissions from energetic runaway electrons also indicated that there is a large population of runaway electrons in the low-density discharge. The non-thermal part of electrons can affect the excitation/transition equilibrium or ionization/recombination equilibrium. The q line is mainly produced by inner-shell excitation of lithium-like argon, and the r line is partially produced by inner-shell excitation of lithium-like argon and dielectronic recombination of helium-like argon.

Phenomena of non-thermal electrons from the X-ray imaging crystal spectrometer on J-TEXT tokamak

Energy Technology Data Exchange (ETDEWEB)

Yan, W. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan (China); Chen, Z.Y., E-mail: zychen@hust.edu.cn [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan (China); Jin, W. [Center of Interface Dynamics for Sustainability, China Academy of Engineering Physics, Chengdu 610200, Sichuan (China); Huang, D.W. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan (China); Lee, S.G.; Shi, Y.J. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Tong, R.H.; Wang, S.Y.; Wei, Y.N.; Ma, T.K.; Zhuang, G. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan (China)

2016-11-01

Highlights: • Some lines from X-ray imaging crystal spectrometer (XICS) can be enhanced by non-thermal electrons, such as q, r satellite lines and z lines. • Analyze the non-thermal phenomena can reduce the error of electron temperature deduced from the intensity ratio of different lines of the He-like argon spectra from XICS. • XICS can be a tool to measure the non-thermal phenomena from these enhanced lines. - Abstract: A high spectra resolution X-ray imaging crystal spectrometer has been implemented on J-TEXT Tokamak for the measurements of K{sub α} spectra of helium-like argon and its satellite lines. The wavelength range of K{sub α} spectra of helium-like argon is from 3.9494 Å to 3.9944 Å that includes the resonance line w, intercombination lines x and y, forbidden line z and numerous satellite lines, referenced using standard Gabriel notation. In low-density discharge, the intensity of q, r satellite lines and z lines can be significantly enhanced by non-thermal electrons. Non-thermal electrons are produced due to the low plasma density. The high hard X-ray flux from NaI detector and significant downshift electron cyclotron emissions from energetic runaway electrons also indicated that there is a large population of runaway electrons in the low-density discharge. The non-thermal part of electrons can affect the excitation/transition equilibrium or ionization/recombination equilibrium. The q line is mainly produced by inner-shell excitation of lithium-like argon, and the r line is partially produced by inner-shell excitation of lithium-like argon and dielectronic recombination of helium-like argon.

Recombination epoch revisited

International Nuclear Information System (INIS)

Krolik, J.H.

1989-01-01

Previous studies of cosmological recombination have shown that this process produces as a by-product a highly superthermal population of Ly-alpha photons which retard completion of recombination. Cosmological redshifting was thought to determine the frequency distribution of the photons, while two-photon decay of hydrogen's 2s state was thought to control their numbers. It is shown here that frequency diffusion due to photon scattering dominate the cosmological redshift in the frequency range near line center which fixes the ratio of ground state to excited state population, while incoherent scattering into the far-red damping wing effectively destroys Ly-alpha photons as a rate which is competitive with two-photon decay. The former effect tends to hold back recombination, while the latter tends to accelerate it; the net results depends on cosmological parameters, particularly the combination Omega(b) h/sq rt (2q0), where Omega(b) is the fraction of the critical density provided by baryons. 18 references

Observations of giant recombination edges on PLT tokamak induced by particle transport

International Nuclear Information System (INIS)

Brau, K.; von Goeler, S.; Bitter, M.; Cowan, R.D.; Eames, D.; Hill, K.; Sauthoff, N.; Silver, E.; Stodiek, W.

1980-03-01

Characteristic steps in the continum spectrum of high temperature tokamak plasmas associated with recombination radiation from impurity ions were observed. During special argon-seeded discharges on the Princeton Large Torus (PLT) tokamak the x-ray spectrum exhibited large enhancements over the bremsstrahlung continuum beginning with energies of 4.1 keV. This corresponds to the radiative capture of free electrons by hydrogen-like argon into the ground state of helium-like argon. A simple particle diffusion model is proposed, with the Ar XVIII radial profiles evaluated from the size of the recombination edges. For the case of moderate density ( approx. 3 x 10 13 cm -3 ) and temperature [T/sub e/(0) approx. 1.5 keV] discharges the outward radial transport velocity is found to be approximately 10 m/sec

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.

QTLs for agronomic traits in the Mediterranean environment identified in recombinant inbred lines of the cross 'Arta' × ¤H. spontaneum¤ 41-1

DEFF Research Database (Denmark)

Baum, M.; Grando, S.; Backes, G.

2003-01-01

A genetic linkage map has been developed for recombinant inbred lines (RILs) of the cross 'Arta' x Hordeum spontaneum 41-1. One hundred and ninety four RILs, randomly chosen from a population of 494 RILs, were mapped with 189 markers including one morphological trait (btr = brittle rachis locus...

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...

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...

Workshop report of problems relating to multi-electron excited ions in plasma

International Nuclear Information System (INIS)

Fujimoto, Takashi; Suzuki, Hiroshi; Takayanagi, Toshinobu; Koike, Fumihiro; Nakamura, Koji.

1979-08-01

A workshop was held to discuss the problems relating to multiple electron-excited ions in plasma. The first part of this report deals with the problems of satellite lines. The satellite lines from laser plasma and vacuum sparks are discussed. Review papers on satellite lines and bielectronic recombination are also presented. The second part of this report deals with the problems of autoionization. Theory, comment on the compound state, observation of autoionization and resonance scattering, excitation cross-section, inner shell ionization, excitation through autoionization, and the bielectronic recombination of helium-like ions are discussed. (Kato, T.)

Experimental evolution across different thermal regimes yields genetic divergence in recombination fraction but no divergence in temperature associated plastic recombination.

Science.gov (United States)

Kohl, Kathryn P; Singh, Nadia D

2018-04-01

Phenotypic plasticity is pervasive in nature. One mechanism underlying the evolution and maintenance of such plasticity is environmental heterogeneity. Indeed, theory indicates that both spatial and temporal variation in the environment should favor the evolution of phenotypic plasticity under a variety of conditions. Cyclical environmental conditions have also been shown to yield evolved increases in recombination frequency. Here, we use a panel of replicated experimental evolution populations of D. melanogaster to test whether variable environments favor enhanced plasticity in recombination rate and/or increased recombination rate in response to temperature. In contrast to expectation, we find no evidence for either enhanced plasticity in recombination or increased rates of recombination in the variable environment lines. Our data confirm a role of temperature in mediating recombination fraction in D. melanogaster, and indicate that recombination is genetically and plastically depressed under lower temperatures. Our data further suggest that the genetic architectures underlying plastic recombination and population-level variation in recombination rate are likely to be distinct. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

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

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

Study of volume recombination and radiation opacity effects in Alcator C-Mod

International Nuclear Information System (INIS)

Terry, J.L.; Lipschultz, B.; Pigarov, A.Y.; Boswell, C.; Krasheninnikov, S.I.; LaBombard, B.; Pappas, D.A.

1998-01-01

Observations of significant volume recombination within the Alcator C-Mod divertor plasma and in the edge plasma (MARFE) are described. The recombination occurs in regions where T e approx-lt 1 eV and n e approx-gt 1x10 21 m -3 . The determinations of the recombination rates are made by measuring the D 0 Lyman and/or Balmer spectra and by using a collisional radiative model describing the level populations, ionization and recombination of D 0 . In regions of strong recombination the upper levels (n approx-gt 4) populations are close to those determined by Saha-Boltzmann distribution and are independent of the ground state density. Thus the intensities of lines from these levels are related to the recombination rate, and curves determining the number of open-quote recombinations per photon close-quote are calculated. Ly β line emission is shown to be trapped in some cases, meaning that Ly α can be strongly trapped. Since opacity affects the recombination rates, the effects of the trapping of Ly α,β photons on the open-quote recombinations per photon close-quote curves are calculated and considered in the recombination rate determinations. Total recombination rates in the detached divertor plasma and in MARFEs located at the periphery of the main plasma are determined. Recombination can be a significant sink for ions. copyright 1998 American Institute of Physics

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...

Are sdAs helium core stars?

Directory of Open Access Journals (Sweden)

Pelisoli Ingrid

2017-12-01

Full Text Available Evolved stars with a helium core can be formed by non-conservative mass exchange interaction with a companion or by strong mass loss. Their masses are smaller than 0.5 M⊙. In the database of the Sloan Digital Sky Survey (SDSS, there are several thousand stars which were classified by the pipeline as dwarf O, B and A stars. Considering the lifetimes of these classes on the main sequence, and their distance modulus at the SDSS bright saturation, if these were common main sequence stars, there would be a considerable population of young stars very far from the galactic disk. Their spectra are dominated by Balmer lines which suggest effective temperatures around 8 000-10 000 K. Several thousand have significant proper motions, indicative of distances smaller than 1 kpc. Many show surface gravity in intermediate values between main sequence and white dwarf, 4.75 < log g < 6.5, hence they have been called sdA stars. Their physical nature and evolutionary history remains a puzzle. We propose they are not H-core main sequence stars, but helium core stars and the outcomes of binary evolution. We report the discovery of two new extremely-low mass white dwarfs among the sdAs to support this statement.

Helium hammer in superfluid transfer

Science.gov (United States)

Tward, E.; Mason, P. V.

1984-01-01

Large transient pressure pulses, referred to as a helium hammer, which occurred in the transfer line of the main cryogenic tank during the development tests of the Infrared Astronomical Satellite, launched on January 25, 1983, are analyzed, and the measures taken to prevent a failure described. The modifications include an installation of a 2.3-liter surge tank upstream, and a back-up relief valve downstream, of a burst disk. The surge tank is designed to attenuate a 0.33-MPa pressure pulse at the inlet down to 0.092 MPa at the outlet. A mechanism of the pulse generation is suggested, which involves flashing and rapid recondensation of the small amount of liquid entering the warm section of a transition to room temperature.

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.

Commissioning of the helium cryogenic system for the HIE- ISOLDE accelerator upgrade at CERN

CERN Document Server

Delruelle, N; Leclercq, Y; Pirotte, O; Williams, L

2015-01-01

The High Intensity and Energy ISOLDE (HIE-ISOLDE) project is a major upgrade of the existing ISOLDE and REX-ISOLDE facilities at CERN. The most significant improvement will come from replacing the existing REX accelerating structure by a superconducting linear accelerator (SC linac) composed ultimately of six cryo-modules installed in series, each containing superconducting RF cavities and solenoids operated at 4.5 K. In order to provide the cooling capacity at all temperature levels between 300 K and 4.5 K for the six cryo-modules, an existing helium refrigerator, manufactured in 1986 and previously used to cool the ALEPH magnet during LEP operation from 1989 to 2000, has been refurbished, reinstalled and recommissioned in a dedicated building located next to the HIE-ISOLDE experimental hall. This helium refrigerator has been connected to a new cryogenic distribution line, consisting of a 30-meter long vacuum-insulated transfer line, a 2000-liter storage dewar and six interconnecting valve boxes, one for eac...

Interpretation of x-ray emission from lithium-like ions in collisions with helium

International Nuclear Information System (INIS)

Armen, G.B.; Aaberg, T.

1994-01-01

We consider the continuous x-ray distribution on the low-energy side of the K α line in projectile spectra coincident with single-electron loss in collision of lithium-like ions with helium. We demonstrate that the observed distributions are due to two-photon emission rather than to the radiative Auger effect. (author)

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

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.

Helium storage and control system for the PBMR

International Nuclear Information System (INIS)

Verkerk, E.C.

1997-01-01

The power conversion unit will convert the heat energy in the reactor core to electrical power. The direct-closed cycle recuperated Brayton Cycle employed for this concept consists of a primary helium cycle with helium powered turbo compressors and a power turbine. The helium is actively cooled with water before the compression stages. A recuperator is used to preheat the helium before entering the core. The start of the direct cycle is initiated by a mass flow from the helium inventory and control system via a jet pump. When the PBMR is connected to the grid, changes in power demand can be followed by changing the helium flow and pressure inside the primary loop. Small rapid adjustments can be performed without changing the helium inventory of the primary loop. The stator blade settings on the turbines and compressors are adjustable and it is possible to bypass reactor and turbine. This temporarily reduces the efficiency at which the power conversion unit is operating. Larger or long term adjustments require storage or addition of helium in order to maintain a sufficient level of efficiency in the power conversion unit. The helium will be temporarily stored in high pressure tanks. After a rise in power demand it will be injected back into the system. Some possibilities how to store the helium are presented in this paper. The change of helium inventory will cause transients in the primary helium loop in order to acquire the desired power level. At this stage, it seems that the change of helium inventory does not strongly effect the stability of the power conversion unit. (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

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.

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

Theoretical pulsation of metallic-line stars

International Nuclear Information System (INIS)

Cox, A.N.; King, D.S.; Hodson, S.W.

1979-01-01

The linear-theory radial-pulsation stability of low-helium delta Scuti variable models (1.0--2.5 Msun) has been investigated to see if metallicism and pulsation can occur simultaneously. Metallicism, which occurs in slowly rotating stars after the gravitational settling of He and the loss of the He II convection zone and its deep mixing for Y< or approx. =0.1, can then be established rapidly compared with the evolution time scale. Pulsation can still occur with driving due to the residual helium and the enhanced hydrogen. With the reduced helium giving no connection zone, the pulsation instability strip, whose blue and edges are estimated in this paoer, is about half as wide as with a normal helium abundance. Zero helium in the surface driving regions, however, produces blue edges so red that probably no instability strip exists at all. The red edge, predicted theoretically on the basis of the importance of convection in the outer zone, agrees well with the observational one. Cool, low-helium and metallic-line stars are then predicted to pulsate in a 200--500 K wide strip that is widest between the main-sequence luminosity of 5 Lsun and 15 Lsun. This strip reasonably includes the observed pulsating delta Del and mild Am stars, but there may be conflicts. Since blue edges for varying ionization-zone helium content occur across the entire instability strip, bluer first and higher overtone pulsations are also predicted everywhere from less than 7000 K to over 8000 K, the redder ones probably showing metallicism

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)

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

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

Influence of the collisional recombination on the electrostatic fluctuation spectrum in an helium plasma

International Nuclear Information System (INIS)

Baravian, G.; Bretagne, J.; Godart, J.; Sultan, G.

1975-01-01

The collisional recombination, in the afterglow of a dense plasma, is regarded as a source process for an overpopulation of the high energy tail of the electron velocity distribution function. The perturbation of the distribution function leads to an important enhancement of the fluctuations of the electrostatic field in a narrow range near the plasma frequency ωsub(p). (orig.) [de

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.

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.)

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

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.)

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.)

Energy transfer in O collisions with He isotopes and helium escape from Mars

Science.gov (United States)

Bovino, S.; Zhang, P.; Kharchenko, V.; Dalgarno, A.

2010-12-01

Helium is one of the dominant constituents in the upper atmosphere of Mars [1]. Thermal (Jeans’) escape of He is negligible on Mars [2] and major mechanism of escape is related to the collisional ejection of He atoms by energetic oxygen. Collisional ejection dominates over ion-related mechanisms [3] and evaluation of the escape flux of neutral He becomes an important issue. The dissociative recombination of O2+ is considered to be the major source of energetic oxygen atoms [4]. We report accurate data on energy-transfer collisions between hot oxygen atoms and the atmospheric helium gas. Angular dependent scattering cross sections for elastic collisions of O(3P) and O(1D) atoms with helium gas have been calculated quantum mechanically and found to be surprisingly similar. Cross sections, computed for collisions with both helium isotopes, 3He and 4He, have been used to construct the kernel of the Boltzmann equation, describing the energy relaxation of hot oxygen atoms. Computed rates of energy transfer in O + He collisions have been used to evaluate the flux of He atoms escaping from the Mars atmosphere at different solar conditions. We have identified atmospheric layers mostly responsible for production of the He escape flux. Our results are consistent with recent data from Monte Carlo simulations of the escape of O atoms: strong angular anisotropy of atomic cross sections leads to an increased transparency of the upper atmosphere for escaping O flux [5] and stimulate the collisional ejection of He atoms. References [1] Krasnopolsky, V. A., and G. R. Gladstone (2005), Helium on Mars and Venus: EUVE observations and modeling, Icarus, 176, 395. [2] Chassefiere E. and F. Leblanc (2004), Mars atmospheric escape and evolution; interaction with the solar wind, Planetary and Space Science, 52, 1039 [3] Krasnopolsky, V. (2010), Solar activity variations of thermospheric temperatures on Mars and a problem of CO in the lower atmoshpere, Icarus, 207, 638. [4] Fox, J. L

Genetic analysis of morphological traits in a new, versatile, rapid-cycling Brassica rapa recombinant inbred line population

Directory of Open Access Journals (Sweden)

Hedayat eBagheri

2012-08-01

Full Text Available A recombinant inbred line (RIL population was produced based on a wide cross between the rapid-cycling and self-compatible genotypes L58, a Caixin vegetable type, and R-o-18, a yellow sarson oil type. A linkage map based on 160 F7 lines was constructed using 100 SNP, 130 AFLP®, 27 InDel and 13 publicly available SSR markers. The map covers a total length of 1150 cM with an average resolution of 4.3 cM/marker. To demonstrate the versatility of this new population, 17 traits, related to plant architecture and seed characteristics, were subjected to QTL analysis. A total of 47 QTLs were detected, each explaining between 6 to 54% of the total phenotypic variance for the concerned trait. The genetic analysis shows that this population is a useful new tool for analyzing genetic variation for interesting traits in B. rapa, and for further exploitation of the recent availability of the B. rapa whole genome sequence for gene cloning and gene function analysis.

Helium trapping in aluminum and sintered aluminum powders

International Nuclear Information System (INIS)

Das, S.K.; Kaminsky, M.; Rossing, T.

1975-01-01

The surface erosion of annealed aluminum and of sintered aluminum powder (SAP) due to blistering from implantation of 100-keV 4 He + ions at room temperature has been investigated. A substantial reduction in the blistering erosion rate in SAP was observed from that in pure annealed aluminum. In order to determine whether the observed reduction in blistering is due to enhanced helium trapping or due to helium released, the implanted helium profiles in annealed aluminum and in SAP have been studied by Rutherford backscattering. The results show that more helium is trapped in SAP than in aluminum for identical irradiation conditions. The observed reduction in erosion from helium blistering in SAP is more likely due to the dispersion of trapped helium at the large Al-Al 2 O 3 interfaces and at the large grain boundaries in SAP than to helium release

Emission profiles of K-He exciplexes in cold helium gas

International Nuclear Information System (INIS)

Allard, N F

2012-01-01

Emission spectra of exciplexes composed of a light alkali atom in the first excited state and 4 He atoms have been observed in cryogenic gas in the spectral range from the atomic D lines to 6300 cm −1 . A unified semi-classical theory of line broadening has been used to determine the total profile from the center to the far wings of emission profiles of potassium perturbed by helium at low temperatures and high He density. The agreement of the theoretical peak positions of K*He n exciplexes compared to the experimental determinations is fairly good. Such comparisons provide a critical test of the calculated molecular potentials and the relevance of the theoretical approach which has been used.

Helium cooling of fusion reactors

International Nuclear Information System (INIS)

Wong, C.P.C.; Baxi, C.; Bourque, R.; Dahms, C.; Inamati, S.; Ryder, R.; Sager, G.; Schleicher, R.

1994-01-01

On the basis of worldwide design experience and in coordination with the evolution of the International Thermonuclear Experimental Reactor (ITER) program, the application of helium as a coolant for fusion appears to be at the verge of a transition from conceptual design to engineering development. This paper presents a review of the use of helium as the coolant for fusion reactor blanket and divertor designs. The concept of a high-pressure helium cooling radial plate design was studied for both ITER and PULSAR. These designs can resolve many engineering issues, and can help with reaching the goals of low activation and high performance designs. The combination of helium cooling, advanced low-activation materials, and gas turbine technology may permit high thermal efficiency and reduced costs, resulting in the environmental advantages and competitive economics required to make fusion a 21st century power source. ((orig.))

Microstructural observation on helium injected and creep ruptured JPCA

International Nuclear Information System (INIS)

Yamamoto, N.; Shiraishi, H.; Hishinuma, A.

1986-01-01

Detailed and quantitative TEM observation was performed on high temperature helium injected and creep ruptured JPCA to seek the prominent TiC distribution developed for suppression of helium embrittlement. Three different preinjection treatments were adopted for changing the TiC distribution. Considerable degradation in creep rupture strength by helium occurred in solution-annealed specimens, although there was much less effect of other treatments which included aging prior to injection. The concentration of helium at grain boundaries and the promotion of precipitation by helium during injection were responsible for the degradation. Therefore, the presence of TiC precipitates before helium introduction will help prevent degradation. On the other hand, the rupture elongation was reduced by helium after all treatments, although helium trapping by TiC precipitates in the matrix was successfully achieved. Consequently, the combined use of several methods may be necessary for further suppression of helium embrittlement. (orig.)

The future of helium as a natural resource

CERN Document Server

Glowacki, Bartek A; Nuttall, William J

2012-01-01

The book reveals the changing dynamics of the helium industry on both the supply-side and the demand-side. The helium industry has a long-term future and this important gas will have a role to play for many decades to come. Major new users of helium are expected to enter the market, especially in nuclear energy (both fission and fusion). Prices and volumes supplied and expected to rise and this will prompt greater efforts towards the development of new helium sources and helium conservation and recycling.

Electronic properties of physisorbed helium

International Nuclear Information System (INIS)

Kossler, Sarah

2011-01-01

This thesis deals with electronic excitations of helium physisorbed on metal substrates. It is studied to what extent the electronic properties change compared to the gas phase due to the increased helium density and the proximity of the metal. Furthermore, the influence of different substrate materials is investigated systematically. To this end, up to two helium layers were adsorbed onto Ru (001), Pt (111), Cu (111), and Ag (111) surfaces in a custom-made cryostat. These samples were studied spectroscopically using synchrotron radiation and a time-of-flight detector. The experimental results were then analyzed in comparison with extensive theoretical model calculations.

Electronic properties of physisorbed helium

Energy Technology Data Exchange (ETDEWEB)

Kossler, Sarah

2011-09-22

This thesis deals with electronic excitations of helium physisorbed on metal substrates. It is studied to what extent the electronic properties change compared to the gas phase due to the increased helium density and the proximity of the metal. Furthermore, the influence of different substrate materials is investigated systematically. To this end, up to two helium layers were adsorbed onto Ru (001), Pt (111), Cu (111), and Ag (111) surfaces in a custom-made cryostat. These samples were studied spectroscopically using synchrotron radiation and a time-of-flight detector. The experimental results were then analyzed in comparison with extensive theoretical model calculations.

Broad-lined Supernova 2016coi with a Helium Envelope

Energy Technology Data Exchange (ETDEWEB)

Yamanaka, Masayuki [Department of Physics, Faculty of Science and Engineering, Konan University, Okamoto, Kobe, Hyogo 658-8501 (Japan); Nakaoka, Tatsuya; Kawabata, Miho [Department of Physical Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526 (Japan); Tanaka, Masaomi [National Astronomical Observatory of Japan, National Institutes of Natural Sciences, Osawa, Mitaka, Tokyo 181-8588 (Japan); Maeda, Keiichi [Department of Astronomy, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Honda, Satoshi; Hosoya, Kensuke; Karita, Mayu; Morihana, Kumiko [Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, 407-2 Nishigaichi, Sayo-cho, Sayo, Hyogo 679-5313 (Japan); Hanayama, Hidekazu [Ishigakijima Astronomical Observatory, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 1024-1 Arakawa, Ishigaki, Okinawa 907-0024 (Japan); Morokuma, Tomoki [Institute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Imai, Masataka [Department of Cosmosciences, Graduate School of Science, Hokkaido University, Kita 10 Nishi8, Kita-ku, Sapporo 060-0810 (Japan); Kinugasa, Kenzo [Nobeyama Radio Observatory, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 462-2 Nobeyama, Minamimaki, Minamisaku, Nagano 384-1305 (Japan); Murata, Katsuhiro L. [Department of Astrophysics, Nagoya University, Chikusa-ku, Nagoya 464-8602 (Japan); Nishimori, Takefumi; Gima, Hirotaka; Ito, Ayano; Morikawa, Yuto; Murakami, Kotone [Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065 (Japan); Hashimoto, Osamu, E-mail: yamanaka@center.konan-u.ac.jp [Gunma Astronomical Observatory, Takayama, Gunma 377-0702 (Japan); and others

2017-03-01

We present the early-phase spectra and the light curves of the broad-lined (BL) supernova (SN) 2016coi from t = 7 to 67 days after the estimated explosion date. This SN was initially reported as a BL Type SN Ic (SN Ic-BL). However, we found that spectra up to t = 12 days exhibited the He i λ 5876, λ 6678, and λ 7065 absorption lines. We show that the smoothed and blueshifted spectra of normal SNe Ib are remarkably similar to the observed spectrum of SN 2016coi. The line velocities of SN 2016coi were similar to those of SNe Ic-BL and significantly faster than those of SNe Ib. Analyses of the line velocity and light curve suggest that the kinetic energy and the total ejecta mass of SN 2016coi are similar to those of SNe Ic-BL. Together with BL SNe 2009bb and 2012ap, for which the detection of He i was also reported, these SNe could be transitional objects between SNe Ic-BL and SNe Ib, and be classified as BL Type “Ib” SNe (SNe “Ib”-BL). Our work demonstrates the diversity of the outermost layer in BL SNe, which should be related to the variety of the evolutionary paths.

Direct-write three-dimensional nanofabrication of nanopyramids and nanocones on Si by nanotumefaction using a helium ion microscope

Science.gov (United States)

Zhang, L.; Heinig, N. F.; Bazargan, S.; Abd-Ellah, M.; Moghimi, N.; Leung, K. T.

2015-06-01

The recently commercialized helium ion microscope (HIM) has already demonstrated its outstanding imaging capabilities in terms of resolution, surface sensitivity, depth of field and ease of charge compensation. Here, we show its exceptional patterning capabilities by fabricating dense lines and three-dimensional (3D) nanostructures on a Si substrate. Small focusing spot size and confined ion-Si interaction volume of a high-energy helium ion beam account for the high resolution in HIM patterning. We demonstrate that a set of resolvable parallel lines with a half pitch as small as 3.5 nm can be achieved. During helium ion bombardment of the Si surface, implantation outperforms milling due to the small mass of the helium ions, which produces tumefaction instead of depression in the Si surface. The Si surface tumefaction is the result of different kinetic processes including diffusion, coalescence and nanobubble formation of the implanted ions, and is found to be very stable structurally at room temperature. Under appropriate conditions, a linear dependence of the surface swollen height on the ion doses can be observed. This relation has enabled us to fabricate nanopyramids and nanocones, thus demonstrating that HIM patterning provides a new ‘bottom-up’ approach to fabricate 3D nanostructures. This surface tumefaction method is direct, both positioning and height accurate, and free of resist, etch, mode and precursor, and it promises new applications in nanoimprint mold fabrication and photomask clear defect reparation.

Direct-write three-dimensional nanofabrication of nanopyramids and nanocones on Si by nanotumefaction using a helium ion microscope

International Nuclear Information System (INIS)

Zhang, L; Heinig, N F; Bazargan, S; Abd-Ellah, M; Moghimi, N; Leung, K T

2015-01-01

The recently commercialized helium ion microscope (HIM) has already demonstrated its outstanding imaging capabilities in terms of resolution, surface sensitivity, depth of field and ease of charge compensation. Here, we show its exceptional patterning capabilities by fabricating dense lines and three-dimensional (3D) nanostructures on a Si substrate. Small focusing spot size and confined ion–Si interaction volume of a high-energy helium ion beam account for the high resolution in HIM patterning. We demonstrate that a set of resolvable parallel lines with a half pitch as small as 3.5 nm can be achieved. During helium ion bombardment of the Si surface, implantation outperforms milling due to the small mass of the helium ions, which produces tumefaction instead of depression in the Si surface. The Si surface tumefaction is the result of different kinetic processes including diffusion, coalescence and nanobubble formation of the implanted ions, and is found to be very stable structurally at room temperature. Under appropriate conditions, a linear dependence of the surface swollen height on the ion doses can be observed. This relation has enabled us to fabricate nanopyramids and nanocones, thus demonstrating that HIM patterning provides a new ‘bottom-up’ approach to fabricate 3D nanostructures. This surface tumefaction method is direct, both positioning and height accurate, and free of resist, etch, mode and precursor, and it promises new applications in nanoimprint mold fabrication and photomask clear defect reparation. (paper)

Extreme ultraviolet spectroscopy of low pressure helium microwave driven discharges

Science.gov (United States)

Espinho, Susana; Felizardo, Edgar; Tatarova, Elena; Alves, Luis Lemos

2016-09-01

Surface wave driven discharges are reliable plasma sources that can produce high levels of vacuum and extreme ultraviolet radiation (VUV and EUV). The richness of the emission spectrum makes this type of discharge a possible alternative source in EUV/VUV radiation assisted applications. However, due to challenging experimental requirements, publications concerning EUV radiation emitted by microwave plasmas are scarce and a deeper understanding of the main mechanisms governing the emission of radiation in this spectral range is required. To this end, the EUV radiation emitted by helium microwave driven plasmas operating at 2.45 GHz has been studied for low pressure conditions. Spectral lines from excited helium atoms and ions were detected via emission spectroscopy in the EUV/VUV regions. Novel data concerning the spectral lines observed in the 23 - 33 nm wavelength range and their intensity behaviour with variation of the discharge operational conditions are presented. The intensity of all the spectral emissions strongly increases with the microwave power delivered to the plasma up to 400 W. Furthermore, the intensity of all the ion spectral emissions in the EUV range decreases by nearly one order of magnitude as the pressure was raised from 0.2 to 0.5 mbar. Work funded by FCT - Fundacao para a Ciencia e a Tecnologia, under Project UID/FIS/50010/2013 and grant SFRH/BD/52412/2013 (PD-F APPLAuSE).

Laser spectroscopy of antiprotonic helium

CERN Document Server

Hori, M

2005-01-01

When antiprotons (i.e. the antimatter counterpart of protons) are stopped in helium gas, 97% of them annihilate within picoseconds by reacting with the helium nuclei; a 3% fraction, however, survive with an anomalously long lifetime of several microseconds. This longevity is due to the formation of antiprotonic helium, which is a three-body Rydberg atom composed of an antiproton, electron, and helium nucleus. The ASACUSA experimental collaboration has recently synthesized large numbers of these atoms using CERN's Antiproton Decelerator facility, and measured the atom's transition frequencies to 60 parts per billion by laser spectroscopy. By comparing the experimental results with recent three-body QED calculations and the known antiproton cyclotron frequency, we were able to show that the antiproton mass and charge are the same as the corresponding proton values to a precision of 10 parts per billion. Ongoing and future series of experiments will further improve the experimental precision by using chirp-compe...

FAST TRACK COMMUNICATION: Contrasting characteristics of sub-microsecond pulsed atmospheric air and atmospheric pressure helium-oxygen glow discharges

Science.gov (United States)

Walsh, J. L.; Liu, D. X.; Iza, F.; Rong, M. Z.; Kong, M. G.

2010-01-01

Glow discharges in air are often considered to be the ultimate low-temperature atmospheric pressure plasmas for numerous chamber-free applications. This is due to the ubiquitous presence of air and the perceived abundance of reactive oxygen and nitrogen species in air plasmas. In this paper, sub-microsecond pulsed atmospheric air plasmas are shown to produce a low concentration of excited oxygen atoms but an abundance of excited nitrogen species, UV photons and ozone molecules. This contrasts sharply with the efficient production of excited oxygen atoms in comparable helium-oxygen discharges. Relevant reaction chemistry analysed with a global model suggests that collisional excitation of O2 by helium metastables is significantly more efficient than electron dissociative excitation of O2, electron excitation of O and ion-ion recombination. These results suggest different practical uses of the two oxygen-containing atmospheric discharges, with air plasmas being well suited for nitrogen and UV based chemistry and He-O2 plasmas for excited atomic oxygen based chemistry.

Femtosecond spectroscopy on alkali-doped helium nanodroplets; Femtosekundenspektroskopie an alkalidotierten Helium-Nanotroepfchen

Energy Technology Data Exchange (ETDEWEB)

Claas, P.

2006-01-15

In the present thesis first studies on the short-time dynamics in alkali dimers and microclusters, which were bound on the surface of superfluid helium droplets, were presented. The experiments comprehended pump-probe measurements on the fs scale on the vibration dynamics on the dimers and on the fragmentation dynamics on the clusters. Generally by the studies it was shown that such extremely short slopes can also be observed on helium droplets by means of the femtosecond spectroscopy.

Helium 3 precipitation in AISI 316L stainless steel induced by radioactive decay of tritium: Microstructural study of helium bubble precipitation

International Nuclear Information System (INIS)

Brass, A.M.; Chene, J.

1994-01-01

The development of the thermonuclear technology has given rise to a renewed interest in the study of the behavior of helium in metals. A great amount of work is still required for the understanding of the role of helium on the mechanical properties of structural materials for fusion technology, especially austenitic stainless steels. This article deals with the study of the influence of thermomechanical heat treatments, aging conditions (temperature and time), and helium concentration of helium bubble precipitation in a 316L austenitic steel. Helium was generated by the radioactive decay of tritium (tritium trick). Helium bubbles impede the grain growth in 316L steel aged at 1,373 K and also the recrystallization reaction at this temperature if cold working is performed prior to aging. Transmission electron microscopy (TEM) observations indicated a weak helium precipitation at 1,073 and 1,223 K, presumably due to the presence of trapping sites for tritium, and no bubble growth after aging up to 100 hours. Precipitation sites are mainly dislocations in the matrix at 1,073 K and grain boundaries and individual dislocations in the matrix at 1,223 K. The large bubble size (50 nm) observed at 1,373 K, even for short aging times (0.083), can partly be attributed to bubble dragging by dislocations toward the grain boundaries. Cold deformation prior to aging leads to a larger bubble size due to growth enhancement during recrystallization. Decreasing the helium content leads to a smaller helium bubble size and density. Tritium trapping at helium bubbles may favor helium 3 accumulation on defects such as grain boundaries, as observed by tritium autoradiography

The adsorption of helium atoms on coronene cations

Energy Technology Data Exchange (ETDEWEB)

Kurzthaler, Thomas; Rasul, Bilal; Kuhn, Martin; Scheier, Paul, E-mail: Paul.Scheier@uibk.ac.at, E-mail: andrew.ellis@le.ac.uk [Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck (Austria); Lindinger, Albrecht [Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin (Germany); Ellis, Andrew M., E-mail: Paul.Scheier@uibk.ac.at, E-mail: andrew.ellis@le.ac.uk [Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)

2016-08-14

We report the first experimental study of the attachment of multiple foreign atoms to a cationic polycyclic aromatic hydrocarbon (PAH). The chosen PAH was coronene, C{sub 24}H{sub 12}, which was added to liquid helium nanodroplets and then subjected to electron bombardment. Using mass spectrometry, coronene cations decorated with helium atoms were clearly seen and the spectrum shows peaks with anomalously high intensities (“magic number” peaks), which represent ion-helium complexes with added stability. The data suggest the formation of a rigid helium layer consisting of 38 helium atoms that completely cover both faces of the coronene ion. Additional magic numbers can be seen for the further addition of 3 and 6 helium atoms, which are thought to attach to the edge of the coronene. The observation of magic numbers for the addition of 38 and 44 helium atoms is in good agreement with a recent path integral Monte Carlo prediction for helium atoms on neutral coronene. An understanding of how atoms and molecules attach to PAH ions is important for a number of reasons including the potential role such complexes might play in the chemistry of the interstellar medium.

Helium release from radioisotope heat sources

Energy Technology Data Exchange (ETDEWEB)

Peterson, D.E.; Early, J.W.; Starzynski, J.S.; Land, C.C.

1984-05-01

Diffusion of helium in /sup 238/PuO/sub 2/ fuel was characterized as a function of the heating rate and the fuel microstructure. The samples were thermally ramped in an induction furnace and the helium release rates measured with an automated mass spectrometer. The diffusion constants and activation energies were obtained from the data using a simple diffusion model. The release rates of helium were correlated with the fuel microstructure by metallographic examination of fuel samples. The release mechanism consists of four regimes, which are dependent upon the temperature. Initially, the release is controlled by movement of point defects combined with trapping along grain boundaries. This regime is followed by a process dominated by formation and growth of helium bubbles along grain boundaries. The third regime involves volume diffusion controlled by movement of oxygen vacancies. Finally, the release at the highest temperatures follows the diffusion rate of intragranular bubbles. The tendency for helium to be trapped within the grain boundaries diminishes with small grain sizes, slow thermal pulses, and older fuel.

Recent developments in liquid helium 3

International Nuclear Information System (INIS)

Ramarao, I.

1977-01-01

The current status of the theories for the ground state of liquid helium 3, are reviewed. To begin with, a brief summary of the experimental results on the thermodynamic properties of liquid helium 3 including its recently discovered superfulid phases is given. The basic ideas of the Landau theory of a normal Fermi liquid are then introduced. A qualitative discussion of the current understanding of the anisotropic phases of superfluid helium 3 is given, the microscopic calculaations for the binding energy of liquid helium 3 are reviewed and the results obtained for the two-body contributions to the binding energy using the Brueckner-Goldstone formulation and that of Mohling and his collaborators are summarized and discussed. The importance of a proper estimate of the three-body contributions to the binding energy is stressed. The results obtained in the literature using variational methods and constrained variational methods are discussed. A critical analysis of the results by various methods is given. Despite much effort the basic problem of the ground state of liquid helium 3, remains unresolved. (author)

Helium release from radioisotope heat sources

International Nuclear Information System (INIS)

Peterson, D.E.; Early, J.W.; Starzynski, J.S.; Land, C.C.

1984-05-01

Diffusion of helium in 238 PuO 2 fuel was characterized as a function of the heating rate and the fuel microstructure. The samples were thermally ramped in an induction furnace and the helium release rates measured with an automated mass spectrometer. The diffusion constants and activation energies were obtained from the data using a simple diffusion model. The release rates of helium were correlated with the fuel microstructure by metallographic examination of fuel samples. The release mechanism consists of four regimes, which are dependent upon the temperature. Initially, the release is controlled by movement of point defects combined with trapping along grain boundaries. This regime is followed by a process dominated by formation and growth of helium bubbles along grain boundaries. The third regime involves volume diffusion controlled by movement of oxygen vacancies. Finally, the release at the highest temperatures follows the diffusion rate of intragranular bubbles. The tendency for helium to be trapped within the grain boundaries diminishes with small grain sizes, slow thermal pulses, and older fuel

Cosmological helium production simplified

International Nuclear Information System (INIS)

Bernstein, J.; Brown, L.S.; Feinberg, G.

1988-01-01

We present a simplified model of helium synthesis in the early universe. The purpose of the model is to explain clearly the physical ideas relevant to the cosmological helium synthesis, in a manner that does not overlay these ideas with complex computer calculations. The model closely follows the standard calculation, except that it neglects the small effect of Fermi-Dirac statistics for the leptons. We also neglect the temperature difference between photons and neutrinos during the period in which neutrons and protons interconvert. These approximations allow us to express the neutron-proton conversion rates in a closed form, which agrees to 10% accuracy or better with the exact rates. Using these analytic expressions for the rates, we reduce the calculation of the neutron-proton ratio as a function of temperature to a simple numerical integral. We also estimate the effect of neutron decay on the helium abundance. Our result for this quantity agrees well with precise computer calculations. We use our semi-analytic formulas to determine how the predicted helium abundance varies with such parameters as the neutron life-time, the baryon to photon ratio, the number of neutrino species, and a possible electron-neutrino chemical potential. 19 refs., 1 fig., 1 tab

Low-temperature centrifugal helium compressor

International Nuclear Information System (INIS)

Kawada, M.; Togo, S.; Akiyama, Y.; Wada, R.

1974-01-01

A centrifugal helium compressor with gas bearings, which can be operated at the temperature of liquid nitrogen, has been investigated. This compressor has the advantages that the compression ratio should be higher than the room temperature operation and that the contamination of helium could be eliminated. The outer diameter of the rotor is 112 mm. The experimental result for helium gas at low temperature shows a flow rate of 47 g/s and a compression ratio of 1.2 when the inlet pressure was 1 ata and the rotational speed 550 rev/s. The investigation is now focused on obtaining a compression ratio of 1.5. (author)

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)

Photographs of quantized vortex lines in rotating superfluid helium

International Nuclear Information System (INIS)

Williams, G.A.

1974-01-01

The spatial positions of quantized vortex lines in rotating He II have been determined using a photographic technique. Electrons are trapped on the vortices and then extracted through the liquid surface and accelerated into a phosphor screen. The light from the phosphor is transmitted to room temperature with coherent fiber optics and photographed with an image intensifier camera. Photographs taken with pure 4 He at T = 0.3 K were complete blurs. These blurs are attributed to nonequilibrium motion of the vortices, arising from the lack of normal fluid damping at this temperature. To resolve the individual vortex lines it was found necessary to add 3 He to the 4 He sample to damp the vortex motion. Photographs are presented for 3 He concentrations up to 1.6 percent. The number of vortices visible varies linearly with rotation speed, but is only about one-half the number expected from theory. The vortex lines in the apparatus were not observed to form a stable array

Application of NIR - CRDS for state selective study of recombination of para and ortho H3+ ions with electrons in low temperature plasma

Science.gov (United States)

Varju, J.; Roučka, Š.; Kotrík, T.; Plašil, R.; Glosík, J.

2010-05-01

We present a study of H3+ recombination performed at 77 K on the two lowest rotational levels of this ion, which belong to its two different nuclear spin states of the studied ion. A near infrared cavity ring-down spectrometer (~1381 nm, CRDS arrangement) has been used to obtain the time evolution of concentration of both states. From the overall ion density decay during the afterglow we obtained the binary recombination rate coefficient αbin (77 K) = 1.2×10-7 cm3s-1. We have also observed ternary helium assisted recombination of both para and ortho H3+. The process is very slow (at 77 K) and the obtained ternary recombination rate coefficient is in contradiction with the theoretical prediction. It is the first time that the binary and ternary H3+ recombination rate coefficient was measured at a known population of para and ortho H3+ ions in decaying plasma.

Application of NIR - CRDS for state selective study of recombination of para and ortho H3+ ions with electrons in low temperature plasma

International Nuclear Information System (INIS)

Varju, J; Roucka, S; KotrIk, T; Plasil, R; Glosik, J

2010-01-01

We present a study of H 3 + recombination performed at 77 K on the two lowest rotational levels of this ion, which belong to its two different nuclear spin states of the studied ion. A near infrared cavity ring-down spectrometer (∼1381 nm, CRDS arrangement) has been used to obtain the time evolution of concentration of both states. From the overall ion density decay during the afterglow we obtained the binary recombination rate coefficient α bin (77 K) = 1.2x10 -7 cm 3 s -1 . We have also observed ternary helium assisted recombination of both para and ortho H 3 + . The process is very slow (at 77 K) and the obtained ternary recombination rate coefficient is in contradiction with the theoretical prediction. It is the first time that the binary and ternary H 3 + recombination rate coefficient was measured at a known population of para and ortho H 3 + ions in decaying plasma.

Helium sources to groundwater in active volcanic terrain, and implications for tritium-helium dating at Mount St. Helens

Energy Technology Data Exchange (ETDEWEB)

Gates, John B. [Department of Earth and Atmospheric Sciences, University of Nebraska-Lincoln, 217 Bessey Hall, Lincoln NE 68588 (United States)

2013-07-01

Groundwater helium sources and residence times were investigated using groundwater discharging from springs surrounding Mount St. Helens in the Cascades region of the United States. Significant contributions of mantle helium were found in all samples and are attributable to interaction between groundwater and magmatic gases. Bounding calculations for residence times were made on the basis of helium isotope mixing plots and historical tritium data. (authors)

Explosive helium burning in white dwarf stars

Energy Technology Data Exchange (ETDEWEB)

Khokhlov, A.M. (AN SSSR, Moscow. Astronomicheskij Sovet)

1984-04-01

Helium burning kinetics in white dwarfs has been considered at constant temperatures T >= 10/sup 9/ K and densities rho >10/sup 5/ g/cm/sup 3/. It is found, that helium detonation in white dwarfs does not lead to formation of light (A < 56) elements. Thus, helium white dwarf model for supernova 1 is inconsistent with observations.

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.)

Role of the Coronal Alfvén Speed in Modulating the Solar-wind Helium Abundance

Science.gov (United States)

Wang, Y.-M.

2016-12-01

The helium abundance He/H in the solar wind is relatively constant at ˜0.04 in high-speed streams, but varies in phase with the sunspot number in slow wind, from ˜0.01 at solar minimum to ˜0.04 at maximum. Suggested mechanisms for helium fractionation have included frictional coupling to protons and resonant interactions with high-frequency Alfvénic fluctuations. We compare He/H measurements during 1995-2015 with coronal parameters derived from source-surface extrapolations of photospheric field maps. We find that the near-Earth helium abundance is an increasing function of the magnetic field strength and Alfvén speed v A in the outer corona, while being only weakly correlated with the proton flux density. Throughout the solar cycle, fast wind is associated with short-term increases in v A near the source surface; resonance with Alfvén waves, with v A and the relative speed of α-particles and protons decreasing with increasing heliocentric distance, may then lead to enhanced He/H at 1 au. The modulation of helium in slow wind reflects the tendency for the associated coronal Alfvén speeds to rise steeply from sunspot minimum, when this wind is concentrated around the source-surface neutral line, to sunspot maximum, when the source-surface field attains its peak strengths. The helium abundance near the source surface may represent a balance between collisional decoupling from protons and Alfvén wave acceleration.

ROLE OF THE CORONAL ALFVÉN SPEED IN MODULATING THE SOLAR-WIND HELIUM ABUNDANCE

Energy Technology Data Exchange (ETDEWEB)

Wang, Y.-M., E-mail: yi.wang@nrl.navy.mil [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)

2016-12-20

The helium abundance He/H in the solar wind is relatively constant at ∼0.04 in high-speed streams, but varies in phase with the sunspot number in slow wind, from ∼0.01 at solar minimum to ∼0.04 at maximum. Suggested mechanisms for helium fractionation have included frictional coupling to protons and resonant interactions with high-frequency Alfvénic fluctuations. We compare He/H measurements during 1995–2015 with coronal parameters derived from source-surface extrapolations of photospheric field maps. We find that the near-Earth helium abundance is an increasing function of the magnetic field strength and Alfvén speed v {sub A} in the outer corona, while being only weakly correlated with the proton flux density. Throughout the solar cycle, fast wind is associated with short-term increases in v {sub A} near the source surface; resonance with Alfvén waves, with v {sub A} and the relative speed of α -particles and protons decreasing with increasing heliocentric distance, may then lead to enhanced He/H at 1 au. The modulation of helium in slow wind reflects the tendency for the associated coronal Alfvén speeds to rise steeply from sunspot minimum, when this wind is concentrated around the source-surface neutral line, to sunspot maximum, when the source-surface field attains its peak strengths. The helium abundance near the source surface may represent a balance between collisional decoupling from protons and Alfvén wave acceleration.

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)

Sound velocity and equation-of-state measurements in high pressure fluid and solid helium

International Nuclear Information System (INIS)

Liebenberg, D.H.; Mills, R.L.; Bronson, J.C.

1979-01-01

A piston--cylinder apparatus was used to obtain P, V, T, and simultaneous values of longitudinal sound velocity in helium fluid throughout the ranges 75 to 300 0 K and 3 to 20 kbar. Some 670 data sets were obtained for the fluid and used in a double-process least-squares fit to an equation of state of the Benedict type. Additional measurements extended across the melting line into the solid phase at pressures up to 18 kbar. Measurements of the compressibility are compared with those obtained by Stewart along the 4 0 K isotherm up to 20 kbar. We discuss the use of helium as a pressure medium in high-pressure diamond anvil cells. Essentially no data are given

Cloning of a Recombinant Plasmid Encoding Thiol-Specific Antioxidant Antigen (TSA) Gene of Leishmania majorand Expression in the Chinese Hamster Ovary Cell Line.

Science.gov (United States)

Fatemeh, Ghaffarifar; Fatemeh, Tabatabaie; Zohreh, Sharifi; Abdolhosein, Dalimiasl; Mohammad Zahir, Hassan; Mehdi, Mahdavi

2012-01-01

TSA (thiol-specific antioxidant antigen) is the immune-dominant antigen of Leishmania major and is considered to be the most promising candidate molecule for a recombinant or DNA vaccine against leishmaniasis. The aim of the present work was to express a plasmid containing the TSA gene in eukaryotic cells. Genomic DNA was extracted, and the TSA gene was amplified by polymerase chain reaction (PCR). The PCR product was cloned into the pTZ57R/T vector, followed by subcloning into the eukaryotic expression vector pcDNA3 (EcoRI and HindIII sites). The recombinant plasmid was characterised by restriction digest and PCR. Eukaryotic Chinese hamster ovary cells were transfected with the plasmid containing the TSA gene. Expression of the L. major TSA gene was confirmed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blotting. The plasmid containing the TSA gene was successfully expressed, as demonstrated by a band of 22.1 kDa on Western blots. The plasmid containing the TSA gene can be expressed in a eukaryotic cell line. Thus, the recombinant plasmid may potentially be used as a DNA vaccine in animal models.

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.

High frequency induction of mitotic recombination by ionizing radiation in Mlh1 null mouse cells

International Nuclear Information System (INIS)

Wang Qi; Ponomareva, Olga N.; Lasarev, Michael; Turker, Mitchell S.

2006-01-01

Mitotic recombination in somatic cells involves crossover events between homologous autosomal chromosomes. This process can convert a cell with a heterozygous deficiency to one with a homozygous deficiency if a mutant allele is present on one of the two homologous autosomes. Thus mitotic recombination often represents the second mutational step in tumor suppressor gene inactivation. In this study we examined the frequency and spectrum of ionizing radiation (IR)-induced autosomal mutations affecting Aprt expression in a mouse kidney cell line null for the Mlh1 mismatch repair (MMR) gene. The mutant frequency results demonstrated high frequency induction of mutations by IR exposure and the spectral analysis revealed that most of this response was due to the induction of mitotic recombinational events. High frequency induction of mitotic recombination was not observed in a DNA repair-proficient cell line or in a cell line with an MMR-independent mutator phenotype. These results demonstrate that IR exposure can initiate a process leading to mitotic recombinational events and that MMR function suppresses these events from occurring

A reciprocating liquid helium pump used for forced flow of supercritical helium

International Nuclear Information System (INIS)

Krafft, G.; Zahn, G.

1978-01-01

The performance of a small double acting piston pump for circulating helium in a closed heat transfer loop is described. The pump was manufactured by LINDE AG, Munich, West Germany. The measured flow rate of supercritical helium was about 17 gs -1 (500 lhr -1 ) with a differential pressure of Δp = 0.5 x 10 5 Nm -2 at a working pressure of p = 6 x 10 5 Nm -2 . At differential pressures beyond 0.5 x 10 5 Nm -2 the volumetric efficiency decreases. (author)

Investigation of helium-induced embrittlement

International Nuclear Information System (INIS)

Sabelova, V.; Slugen, V.; Krsjak, V.

2014-01-01

In this work, the hardness of Fe-9%(wt.) Cr binary alloy implanted by helium ions up to 1000 nm was investigated. The implantations were performed using linear accelerator at temperatures below 80 grad C. Isochronal annealing up to 700 grad C with the step of 100 grad C was applied on the helium implanted samples in order to investigate helium induced embrittlement of material. Obtained results were compared with theoretical calculations of dpa profiles. Due to the results, the nano-hardness technique results to be an appropriate approach to the hardness determination of thin layers of implanted alloys. Both, experimental and theoretical calculation techniques (SRIM) show significant correlation of measured results of induced defects. (authors)

A review of recent theoretical developments in the understanding of the migration of helium in metals and its interaction with lattice defects

International Nuclear Information System (INIS)

Reed, D.J.

1977-01-01

Recent theoretical calculations of the properties of rare gases, and in particular helium, in the common f.c.c. and b.c.c. metals, are reviewed from the viewpoint of the investigator concerned with the behaviour of rare gas in such radiation damage processes as surface blistering and void swelling. Particular attention is paid to mechanisms by which helium may migrate in a damaged metal lattice during irradiation and to the properties of small gas and vacancy clusters which may represent bubble or void nuclei. Initially the proposed rapid migration of interstitial helium is discussed together with the substitutional de-trapping mechanism, whereby thermally activated helium jumps from a substitutional to an interstitial position. This enables a mechanism of substitutional helium diffusion to be proposed which may proceed at temperatures below those of self-diffusion. The formation, binding, migration and dissociation energies of gas-vacancy clusters have been reviewed. The relevance of the predicted trend towards the optimum stability of clusters composed of equal numbers of gas atoms and vacancies is discussed. The limited data available concerned with the binding of a helium atom to a pure dislocation line is presented together with comments on the possible nature of the interaction of helium with the dislocation jog. (author)

The TEXTOR helium self-pumping experiment: Design, plans, and supporting ion-beam data on helium retention in nickel

International Nuclear Information System (INIS)

Brooks, J.N.; Krauss, A.; Mattas, R.F.; Smith, D.L.; Nygren, R.E.; Doyle, B.L.; McGrath, R.T.; Walsh, D.; Dippel, K.H.; Finken, K.H.

1990-01-01

A proof-of-principle experiment to demonstrate helium self-pumping in a tokamak is being undertaken in TEXTOR. The experiment will use a helium self-pumping module installed in a modified ALT-I limiter head. The module consists of two, ≅ 25x25 cm 2 heated nickel alloy trapping plates, a nickel deposition filament array, and associated diagnostics. Between plasma shots a coating of ≅ 50A nickel will be deposited on the two trapping plates. During a shot helium and hydrogen ions will impinge on the plates through a ≅ 3 cm wide entrance slot. The helium removal capability, due to trapping in the nickel, will be assessed for a variety of plasma conditions. In support of the tokamak experiment, the trapping of helium over a range of ion fluences and surface temperatures, and detrapping during subsequent exposure to hydrogen, were measured in ion beam experiments using evaporated nickel surfaces similar to that expected in TEXTOR. Also, the retention of H and He after exposure of a nickel surface to mixed He/H plasmas has been measured. The results appear favorable, showing high helium trapping (≅ 10-50% He/Ni) and little or no detrapping by hydrogen. The TEXTOR experiment is planned to begin in 1991. (orig.)

The TEXTOR helium self-pumping experiment: Design, plans, and supporting ion-beam data on helium retention in nickel

International Nuclear Information System (INIS)

Brooks, J.N.; Krauss, A.; Mattas, R.F.; Smith, D.L.; Nygren, R.E.; Doyle, B.L.; McGrath, R.T.; Walsh, D.; Dippel, K.H.; Finken, K.H.

1990-01-01

A proof-of-principle experiment to demonstrate helium self-pumping in a tokamak is being undertaken in TEXTOR. The experiment will use a helium self-pumping module installed in a modified ALT-I limiter head. The module consists of two, ∼25 x 25 cm 2 heated nickel alloy trapping plates, a nickel deposition filament array, and associated diagnostics. Between plasma shots a coating of ∼50 angstrom nickel will be deposited on the two trapping plates. During a shot helium and hydrogen ions will impinge on the plates through a ∼3 cm wide entrance slot. The helium removal capability, due to trapping in the nickel, will be assessed for a variety of plasma conditions. In support of the tokamak experiment, the trapping of helium over a range of ion fluences and surface temperatures, and detrapping during subsequent exposure to hydrogen, were measured in ion beam experiments using evaporated nickel surfaces similar to that expected in TEXTOR. Also, the retention of H and He after exposure of a nickel surface to mixed He/H plasmas has bee measured. The results appear favorable, showing high helium trapping (∼10--50% He/Ni) and little or no detrapping by hydrogen. The TEXTOR experiment is planned to begin in 1991. 12 refs., 2 figs., 2 tabs

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

Selective excitation of singly-ionized silver emission lines by Grimm glow discharge plasmas using several different plasma gases

International Nuclear Information System (INIS)

Wagatsuma, K.

1996-01-01

The relative intensities of silver emission lines from Grimm glow discharge plasmas were investigated in the wavelength range from 160 to 600 nm when using different plasma gases. It was characteristic of the plasma excitation that the spectral patterns were strongly dependent on the nature of the plasma gas employed. Intense emission lines of silver ion were observed when argon-helium mixed gases were employed as the plasma gas. Selective excitation of the ionic lines could be principally attributed to the charge transfer collisions between silver atoms and helium ions. (orig.)

Helium production in reactor materials

International Nuclear Information System (INIS)

Lippincott, E.P.; McElroy, W.N.; Farrar, H. IV.

1975-02-01

Comparisons of integral helium production measurements with predictions based on ENDF/B Version IV cross sections have been made. It is concluded that an ENDF/B helium production cross section file should be established in order to ensure a complete and consistent cross section evaluation to meet accuracies required for LMFBR, CTR, and LWR applications. (U.S.)

Infrared spectroscopy of the ν3 band of C3 in helium droplets

Directory of Open Access Journals (Sweden)

Barbara A. Harruff-Miller

2018-02-01

Full Text Available The C3 molecule is an important species known to participate in key chemical reactions in combustion and astrochemistry. Its occurrence in environments of interest, its intramolecular physics, and its intermolecular reactivity have been areas of extensive and ongoing study. Much of the interest in C3 is related to investigating its interactions with other species relevant to combustion processes or astrochemistry. Helium droplet methods offer a promising route to assemble and study a wide variety of novel complexes, clusters, and adducts made from C3. Here we report the results of our recent efforts to dope cold helium droplets with C3 molecules and record the rotationally-resolved infrared spectrum of the embedded C3. The spectrum consists of P(2, R(0, and R(2 lines well-described by a linear rotor Hamiltonian with ν0 = 2039.09(2 cm-1, B = 0.204(5 cm-1, and T = 0.37 K. The B rotational constant of the C3 molecule is found to be reduced from its gas-phase value by a factor of 2.1 due to rotational following by the helium solvent.

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

Modeling Secondary Neutral Helium in the Heliosphere

International Nuclear Information System (INIS)

Müller, Hans-Reinhard; Möbius, Eberhard; Wood, Brian E.

2016-01-01

An accurate, analytic heliospheric neutral test-particle code for helium atoms from the interstellar medium (ISM) is coupled to global heliospheric models dominated by hydrogen and protons from the solar wind and the ISM. This coupling enables the forward-calculation of secondary helium neutrals from first principles. Secondaries are produced predominantly in the outer heliosheath, upwind of the heliopause, by charge exchange of helium ions with neutral atoms. The forward model integrates the secondary production terms along neutral trajectories and calculates the combined neutral helium phase space density in the innermost heliosphere where it can be related to in-situ observations. The phase space density of the secondary component is lower than that of primary neutral helium, but its presence can change the analysis of primaries and the ISM, and can yield valuable insight into the characteristics of the plasma in the outer heliosheath. (paper)

Behaviour of helium after implantation in molybdenum

International Nuclear Information System (INIS)

Viaud, C.; Maillard, S.; Carlot, G.; Valot, C.; Gilabert, E.; Sauvage, T.; Peaucelle, C.; Moncoffre, N.

2009-01-01

This study deals with the behaviour of helium in a molybdenum liner dedicated to the retention of fission products. More precisely this work contributes to evaluate the release of implanted helium when the gas has precipitated into nanometric bubbles close to the free surface. A simple model dedicated to calculate the helium release in such a condition is presented. The specificity of this model lays on the assumption that the gas is in equilibrium with a simple distribution of growing bubbles. This effort is encouraging since the calculated helium release fits an experimental dataset with a set of parameters in good agreement with the literature

Use of helium in uranium exploration, Grants district

International Nuclear Information System (INIS)

DeVoto, R.H.; Mead, R.H.; Martin, J.P.; Bergquist, L.E.

1980-01-01

The continuous generation of inert helium gas from uranium and its daughter products provides a potentially useful means for remote detection of uranium deposits. The practicality of conducting helium surveys in the atmosphere, soil gas, and ground water to explore for buried uranium deposits has been tested in the Grants district and in the Powder River Basin of Wyoming. No detectable helium anomalies related to buried or surface uranium deposits were found in the atmosphere. However, reproducible helium-in-soil-gas anomalies were detected spatially related to uranium deposits buried from 50 to 800 ft deep. Diurnal and atmospheric effects can cause helium content variations (noise) in soil gas that are as great as the anomalies observed from instantaneous soil-gas samples. Cumulative soil-gas helium analyses, such as those obtained from collecting undisturbed soil samples and degassing them in the laboratory, may reveal anomalies from 5 to 100 percent above background. Ground water samples from the Grants district, New Mexico, and the Powder River Basin, Wyoming, have distinctly anomalous helium values spatially related to buried uranium deposits. In the southern Powder River Basin, helium values 20 to 200 percent above background occur 2 to 18 mile down the ground-water flow path from known uranium roll-front deposits. In the Grants district, helium contents 40 to 700 percent above background levels are present in ground waters from the host sandstone in the vicinity of uranium deposits and from aquifers up to 3,000 ft stratigraphically above the deep uranium deposits. The use of helium in soil and ground-water surveys, along with uranium and radon analyses of the same materials, is strongly recommended is expensive, deep, uranium-exploration programs such as those being conducted in the Grants district

Algae-based oral recombinant vaccines

Science.gov (United States)

Specht, Elizabeth A.; Mayfield, Stephen P.

2014-01-01

Recombinant subunit vaccines are some of the safest and most effective vaccines available, but their high cost and the requirement of advanced medical infrastructure for administration make them impractical for many developing world diseases. Plant-based vaccines have shifted that paradigm by paving the way for recombinant vaccine production at agricultural scale using an edible host. However, enthusiasm for “molecular pharming” in food crops has waned in the last decade due to difficulty in developing transgenic crop plants and concerns of contaminating the food supply. Microalgae could be poised to become the next candidate in recombinant subunit vaccine production, as they present several advantages over terrestrial crop plant-based platforms including scalable and contained growth, rapid transformation, easily obtained stable cell lines, and consistent transgene expression levels. Algae have been shown to accumulate and properly fold several vaccine antigens, and efforts are underway to create recombinant algal fusion proteins that can enhance antigenicity for effective orally delivered vaccines. These approaches have the potential to revolutionize the way subunit vaccines are made and delivered – from costly parenteral administration of purified protein, to an inexpensive oral algae tablet with effective mucosal and systemic immune reactivity. PMID:24596570

Algae-based oral recombinant vaccines

Directory of Open Access Journals (Sweden)

Elizabeth A Specht

2014-02-01

Full Text Available Recombinant subunit vaccines are some of the safest and most effective vaccines available, but their high cost and the requirement of advanced medical infrastructure for administration make them impractical for many developing world diseases. Plant-based vaccines have shifted that paradigm by paving the way for recombinant vaccine production at agricultural scale using an edible host. However, enthusiasm for molecular pharming in food crops has waned in the last decade due to difficulty in developing transgenic crop plants and concerns of contaminating the food supply. Microalgae are poised to become the next candidate in recombinant subunit vaccine production, and they present several advantages over terrestrial crop plant-based platforms including scalable and contained growth, rapid transformation, easily obtained stable cell lines, and consistent transgene expression levels. Algae have been shown to accumulate and properly fold several vaccine antigens, and efforts are underway to create recombinant algal fusion proteins that can enhance antigenicity for effective orally-delivered vaccines. These approaches have the potential to revolutionize the way subunit vaccines are made and delivered – from costly parenteral administration of purified protein, to an inexpensive oral algae tablet with effective mucosal and system immune reactivity.

Manufacturing cycle for pure neon-helium mixture production

International Nuclear Information System (INIS)

Batrakov, B.P.; Kravchenko, V.A.

1980-01-01

The manufacturing cycle for pure neon-helium mixture production with JA-300 nitrogen air distributing device has been developed. Gas mixture containing 2-3% of neon-helium mixture (the rest is mainly nitrogen 96-97%) is selected out of the cover of the JA-300 column condensator and enters the deflegmator under the 2.3-2.5 atm. pressure. The diflegmator presents a heat exchange apparatus in which at 78 K liquid nitrogen the condensation of nitrogen from the mixture of gases entering from the JA-300 column takes place. The enriched gas mixture containing 65-70% of neon-helium mixture and 30-35% of nitrogen goes out from the deflegmator. This enriched neon-helium mixture enters the gasgoeder for impure (65-70%) neon-helium mixture. Full cleaning of-neon helium mixture of nitrogen is performed by means of an adsorber. As adsorbent an activated coal has been used. Adsorption occurs at the 78 K temperature of liquid nitrogen and pressure P=0.1 atm. As activated coal cooled down to nitrogen temperature adsorbs nitrogen better than neon and helium, the nitrogen from the mixture is completely adsorbed. Pure neon-helium mixture from the adsorber comes into a separate gasgolder. In one campaign the cycle allows obtaining 2 m 3 of the mixture. The mixture contains 0.14% of nitrogen, 0.01% of oxygen and 0.06% of hydrogen

Comparison of poliovirus recombinants: accumulation of point mutations provides further advantages.

Science.gov (United States)

Savolainen-Kopra, Carita; Samoilovich, Elena; Kahelin, Heidi; Hiekka, Anna-Kaisa; Hovi, Tapani; Roivainen, Merja

2009-08-01

The roles of recombination and accumulation of point mutations in the origin of new poliovirus (PV) characteristics have been hypothesized, but it is not known which are essential to evolution. We studied phenotypic differences between recombinant PV strains isolated from successive stool specimens of an oral PV vaccine recipient. The studied strains included three PV2/PV1 recombinants with increasing numbers of mutations in the VP1 gene, two of the three with an amino acid change I-->T in the DE-loop of VP1, their putative PV1 parent and strains Sabin 1 and 2. Growth of these viruses was examined in three cell lines: colorectal adenocarcinoma, neuroblastoma and HeLa. The main observation was a higher growth rate between 4 and 6 h post-infection of the two recombinants with the I-->T substitution. All recombinants grew at a higher rate than parental strains in the exponential phase of the replication cycle. In a temperature sensitivity test, the I-->T-substituted recombinants replicated equally well at an elevated temperature. Complete genome sequencing of the three recombinants revealed 12 (3), 19 (3) and 27 (3) nucleotide (amino acid) differences from Sabin. Mutations were located in regions defining attenuation, temperature sensitivity, antigenicity and the cis-acting replicating element. The recombination site was in the 5' end of 3D. In a competition assay, the most mutated recombinant beat parental Sabin in all three cell lines, strongly suggesting that this virus has an advantage. Two independent intertypic recombinants, PV3/PV1 and PV3/PV2, also showed similar growth advantages, but they also contained several point mutations. Thus, our data defend the hypothesis that accumulation of certain advantageous mutations plays a key role in gaining increased fitness.

Standard Guide for Simulation of Helium Effects in Irradiated Metals

CERN Document Server

American Society for Testing and Materials. Philadelphia

1996-01-01

1.1 This guide provides advice for conducting experiments to investigate the effects of helium on the properties of metals where the technique for introducing the helium differs in some way from the actual mechanism of introduction of helium in service. Simulation techniques considered for introducing helium shall include charged particle implantation, exposure to α-emitting radioisotopes, and tritium decay techniques. Procedures for the analysis of helium content and helium distribution within the specimen are also recommended. 1.2 Two other methods for introducing helium into irradiated materials are not covered in this guide. They are the enhancement of helium production in nickel-bearing alloys by spectral tailoring in mixed-spectrum fission reactors, and isotopic tailoring in both fast and mixed-spectrum fission reactors. These techniques are described in Refs (1-5). Dual ion beam techniques (6) for simultaneously implanting helium and generating displacement damage are also not included here. This lat...

A search for evidence of below threshold dielectronic recombination in low temperature plasmas

Science.gov (United States)

Nemer, Ahmad; Loch, Stuart; Sterling, Nicholas C.; Raymond, John C.

2018-06-01

There are two main types of photoionized gaseous nebulae that exist in the universe, H II regions and Planetary Nebulae (PNe), that mark the endpoints of stellar evolution, and understanding their composition will lead to better understanding of stellar evolution processes, and galactic chemical nucleosynthesis. Determination of heavy elements’ abundances is essential in the analysis of these nebulae. In addition, lines emitted from these heavy elements are typically used for nebular condition deduction. There has been a long-standing problem regarding discrepancy of temperatures and abundances resolved from optical recombination lines and collisionally excited lines. One of the reasons suggested to explain the discrepancy is Dielectronic Recombination (DR). DR is thought to necessarily occur through continuum states overlapping with autoionizing states that are above the ionization threshold. Robicheaux et al. (2010) proposed that DR to below threshold states is possible through ‘negative’ energy electrons recombining to below threshold doubly excited states. The spectral lines emitted from this process could provide an efficient mechanism to cool off plasma in addition to having satellite lines blended with collisionally excited lines related to plasma diagnostics. Furthermore, this phenomenon would occur significantly in low temperature plasmas which makes it challenging to prepare an experiment for testing it in a lab. In this research we present a spectroscopic study into this process through observed optical spectra from seven PNe that suffer from abundance discrepancy problem. A code was developed that produces a synthetic spectrum for 2 cases; namely, C IV recombining to C III and C III to C II. There is faint emission in the optical for these cases. Other possible mechismas to activiate these lines were included in the model and found insignificant. The Auger rates were calculated using the atomic physics code AUTOSTRUCTURE, and the lines were

Helium-induced weld degradation of HT-9 steel

International Nuclear Information System (INIS)

Wang, Chin-An; Chin, B.A.; Lin, Hua T.; Grossbeck, M.L.

1992-01-01

Helium-bearing Sandvik HT-9 ferritic steel was tested for weldability to simulate the welding of structural components of a fusion reactor after irradiation. Helium was introduced into HT-9 steel to 0.3 and 1 atomic parts per million (appm) by tritium doping and decay. Autogenous single pass full penetration welds were produced using the gas tungsten arc (GTA) welding process under laterally constrained conditions. Macroscopic examination showed no sign of any weld defect in HT-9 steel containing 0.3 appm helium. However, intergranular micro cracks were observed in the HAZ of HT-9 steel containing 1 appm helium. The microcracking was attributed to helium bubble growth at grain boundaries under the influence of high stresses and temperatures that were present during welding. Mechanical test results showed that both yield strength (YS) and ultimate tensile strength (UTS) decreased with increasing temperature, while the total elongation increased with increasing temperature for all control and helium-bearing HT-9 steels

GBT Measurements of the Physical Properties of the Sgr B2 Region

Science.gov (United States)

Langston, Glen; Schmidt, D. R.; Christiansen, K.

2012-01-01

We present NRAO GBT observations of ammonia 1-1 and 2-2 emission in the Sgr B2 region, in order to estimate the physical temperature of this region. The observations were made with the 7-beam K-band Focal Plane Array (KFPA) collecting spectra over a 11' by 9' region. We compare these observations with molecular line spectra obtained with the GBT in the frequency range 12.4 to 15.0 GHz. In this frequency range, Hydrogen α, β, and γ recombination lines, Helium α recombination lines and emission from the SO molecule are detected. Molecular absorption lines from OH, H2CO and CH3CO are detected at velocity 62×3 km/sec. Measurements of the line widths and intensities are presented for the central region of Sgr B2.

Non-local Thermodynamic Equilibrium Abundance Analyses of the Extreme Helium Stars V652 Her and HD 144941

International Nuclear Information System (INIS)

Pandey, Gajendra; Lambert, David L.

2017-01-01

Optical high-resolution spectra of V652 Her and HD 144941, the two extreme helium stars with exceptionally low C/He ratios, have been subjected to a non-LTE abundance analysis using the tools TLUSTY and SYNSPEC. Defining atmospheric parameters were obtained from a grid of non-LTE atmospheres and a variety of spectroscopic indicators including He i and He ii line profiles, and the ionization equilibrium of ion pairs such as C ii/C iii and N ii/N iii. The various indicators provide a consistent set of atmospheric parameters: T eff = 25,000 ± 300 K, log g = 3.10 ± 0.12(cgs), and ξ = 13 ± 2 km s −1 are provided for V652 Her, and T eff = 22,000 ± 600 K, log g = 3.45 ± 0.15 (cgs), and ξ = 10 km s −1 are provided for HD 144941. In contrast to the non-LTE analyses, the LTE analyses—LTE atmospheres and an LTE line analysis—with the available indicators do not provide a consistent set of atmospheric parameters. The principal non-LTE effect on the elemental abundances is on the neon abundance. It is generally considered that these extreme helium stars with their very low C/He ratio result from the merger of two helium white dwarfs. Indeed, the derived composition of V652 Her is in excellent agreement with predictions by Zhang and Jeffery, who model the slow merger of helium white dwarfs; a slow merger results in the merged star having the composition of the accreted white dwarf. In the case of HD 144941, which appears to have evolved from metal-poor stars, a slow merger is incompatible with the observed composition but variations of the merger rate may account for the observed composition. More detailed theoretical studies of the merger of a pair of helium white dwarfs are to be encouraged.

Non-local Thermodynamic Equilibrium Abundance Analyses of the Extreme Helium Stars V652 Her and HD 144941

Energy Technology Data Exchange (ETDEWEB)

Pandey, Gajendra [Indian Institute of Astrophysics, Bangalore, 560034 (India); Lambert, David L., E-mail: pandey@iiap.res.in, E-mail: dll@astro.as.utexas.edu [The W.J. McDonald Observatory and Department of Astronomy, University of Texas at Austin, Austin, TX 78712-1083 (United States)

2017-10-01

Optical high-resolution spectra of V652 Her and HD 144941, the two extreme helium stars with exceptionally low C/He ratios, have been subjected to a non-LTE abundance analysis using the tools TLUSTY and SYNSPEC. Defining atmospheric parameters were obtained from a grid of non-LTE atmospheres and a variety of spectroscopic indicators including He i and He ii line profiles, and the ionization equilibrium of ion pairs such as C ii/C iii and N ii/N iii. The various indicators provide a consistent set of atmospheric parameters: T {sub eff} = 25,000 ± 300 K, log g = 3.10 ± 0.12(cgs), and ξ = 13 ± 2 km s{sup −1} are provided for V652 Her, and T {sub eff} = 22,000 ± 600 K, log g = 3.45 ± 0.15 (cgs), and ξ = 10 km s{sup −1} are provided for HD 144941. In contrast to the non-LTE analyses, the LTE analyses—LTE atmospheres and an LTE line analysis—with the available indicators do not provide a consistent set of atmospheric parameters. The principal non-LTE effect on the elemental abundances is on the neon abundance. It is generally considered that these extreme helium stars with their very low C/He ratio result from the merger of two helium white dwarfs. Indeed, the derived composition of V652 Her is in excellent agreement with predictions by Zhang and Jeffery, who model the slow merger of helium white dwarfs; a slow merger results in the merged star having the composition of the accreted white dwarf. In the case of HD 144941, which appears to have evolved from metal-poor stars, a slow merger is incompatible with the observed composition but variations of the merger rate may account for the observed composition. More detailed theoretical studies of the merger of a pair of helium white dwarfs are to be encouraged.

recombinant inbred lines intercropped with oat

African Journals Online (AJOL)

ADMIN

The QTLs identified are stable for these characters and are located on ... number of seeds per ear, with better thousand kernel weight and grain yield ... to determine environmentally friendly way of barley lines to withstand oat .... The analysis of variance (ANOVA) was done .... yield components, multiple QTL mapping or.

Charged condensate and helium dwarf stars

Energy Technology Data Exchange (ETDEWEB)

Gabadadze, Gregory; Rosen, Rachel A, E-mail: gg32@nyu.edu, E-mail: rar339@nyu.edu [Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, NY 10003 (United States)

2008-10-15

White dwarf stars composed of carbon, oxygen and heavier elements are expected to crystallize as they cool down below certain temperatures. Yet, simple arguments suggest that the helium white dwarf cores may not solidify, mostly because of zero-point oscillations of the helium ions that would dissolve the crystalline structure. We argue that the interior of the helium dwarfs may instead form a macroscopic quantum state in which the charged helium-4 nuclei are in a Bose-Einstein condensate, while the relativistic electrons form a neutralizing degenerate Fermi liquid. We discuss the electric charge screening, and the spectrum of this substance, showing that the bosonic long-wavelength fluctuations exhibit a mass gap. Hence, there is a suppression at low temperatures of the boson contribution to the specific heat-the latter being dominated by the specific heat of the electrons near the Fermi surface. This state of matter may have observational signatures.

On the helium gas leak test

International Nuclear Information System (INIS)

Nishikawa, Akira; Ozaki, Susumu

1975-01-01

The helium gas leak test (Helium mass spectrometer testing) has a leak detection capacity of the highest level in practical leak tests and is going to be widely applied to high pressure vessels, atomic and vacuum equipments that require high tightness. To establish a standard test procedure several series of experiments were conducted and the results were investigated. The conclusions are summarized as follows: (1) The hood method is quantitatively the most reliable method. The leak rate obtained by tests using 100% helium concentration should be the basis of the other method of test. (2) The integrating method, bell jar method, and vacuum spray method can be considered quantitative when particular conditions are satisfied. (3) The sniffer method is not to be considered quantitive. (4) The leak rate of the hood, integrating, and bell jar methods is approximately proportional to the square of the helium partial pressure. (auth.)

Recombination rate variation in mice from an isolated island.

Science.gov (United States)

Wang, Richard J; Gray, Melissa M; Parmenter, Michelle D; Broman, Karl W; Payseur, Bret A

2017-01-01

Recombination rate is a heritable trait that varies among individuals. Despite the major impact of recombination rate on patterns of genetic diversity and the efficacy of selection, natural variation in this phenotype remains poorly characterized. We present a comparison of genetic maps, sampling 1212 meioses, from a unique population of wild house mice (Mus musculus domesticus) that recently colonized remote Gough Island. Crosses to a mainland reference strain (WSB/EiJ) reveal pervasive variation in recombination rate among Gough Island mice, including subchromosomal intervals spanning up to 28% of the genome. In spite of this high level of polymorphism, the genomewide recombination rate does not significantly vary. In general, we find that recombination rate varies more when measured in smaller genomic intervals. Using the current standard genetic map of the laboratory mouse to polarize intervals with divergent recombination rates, we infer that the majority of evolutionary change occurred in one of the two tested lines of Gough Island mice. Our results confirm that natural populations harbour a high level of recombination rate polymorphism and highlight the disparities in recombination rate evolution across genomic scales. © 2016 John Wiley & Sons Ltd.

Probing the properties of nebular plasmas with optical and infrared spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Barlow, M. J. [Dept. of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom)

2012-05-25

A number of current developments arising from spectroscopic studies of ionized nebulae are reviewed. Until the past decade or so, such studies were generally confined to the analysis of recombination lines from hydrogen and helium, along with collisionally excited forbidden lines from second and third row elements in the periodic table. However, the advent of efficient detectors on 8m-class telescopes has enabled the detection of recombination lines from second and third row elements, along with collisionally excited lines from much less abundant species. Significant discrepancies have been found between ionic abundances derived from collisionally excited lines and those obtained for the same ions from their recombination lines. The existence of 'cold plasma' with T{sub e}{<=} 1000 K has been confirmed for a number of planetary nebulae. Optical and infrared collisionally excited ionic lines from a wide range of 'neutron-capture' elements from beyond the iron abundance peak have also been detected. There is a consequent need for new calculations and experimental measurements of the atomic data needed to interpret these observations.

Cryogenic supplies for the TFTR neutral beam line cryopanels

International Nuclear Information System (INIS)

Pinter, G.

1977-01-01

Cryocondensing panels will be used for the Neutral Beam Lines of the TFTR to satisfy a pumping speed requirement of 2.5 x 10 6 l/s. The cryocondensing panels are fed by liquid helium (LHe), boiling at selectable temperatures of 4.5 0 K or 3.8 0 K. Liquid nitrogen (LN 2 ) panels and chevrons thermally shield the LHe panel. The closed-loop LHe supply system and the open loop LN 2 system are discussed. The helium refrigerator of minimum 1070-W capacity, together with its distribution system, and the nitrogen distribution system in the ton/hour LN 2 range is presented. Problems and their solutions in connection with the LHe system, including the distribution over a distance of 500 feet of large quantities of liquid/gas mixtures with load variations over the range of about 3 : 1, and the economies of various types of distribution lines (passive, pumped, shielded, combined), are described. The system design passed the preliminary phase. Design features and auxiliary equipment to assure dispersion of large quantities of nitrogen into the atmosphere and to permit operation under degraded cryogenic helium refrigerator performance are also discussed in Design Considerations

ERO modeling of beryllium erosion by helium plasma in experiments at PISCES-B

Directory of Open Access Journals (Sweden)

D. Borodin

2017-08-01

Full Text Available The beryllium erosion by helium plasma irradiation is studied at the PISCES-B linear plasma device and interpreted using the accompanying simulations by the ERO code. The influence of plasma conditions and varying negative biasing of the Be plasma target on BeI and BeII absolute line intensities are reproduced in detail by the simulations. The synthetic axial line intensity shapes and line ratios match with experiment. This indicates that atomic data are quite accurate. The initial population state of quasi-metastable 3P level in BeI is found to be MS:GS= 0.33:1 for all conditions. The yields determined by the modeling interpretation are compared to the SDTrimSP code simulations in the binary collision approximation.

Containment air circulation for optimal hydrogen recombination

International Nuclear Information System (INIS)

Spinks, N.; Krause, M.

1997-01-01

An accepted first-line defense for hydrogen mitigation is to design for the hydrogen to be rapidly mixed with the containment atmosphere and diluted to below flammability concentrations. Then, as hydrogen continues to be produced in the longer term, recombiners can be used to remove hydrogen: recombiners can be located in forced-air ducts or passive recombiners can be distributed within containment and the heat of recombination used to promote local air circulation. However, this principle does not eliminate the possibility of high hydrogen concentrations at locations removed from the recombiners. An improvement on this strategy is to arrange for a specific, buoyancy-driven, overall circulation of the containment atmosphere such that the recombiners can be located within the recirculation flow, immediately downstream of the hydrogen source. This would make the mixing process more predictable and solve the mass-transfer problem associated with distributed recombiners. Ideally, the recombiners would be located just above the hydrogen source so that the heat of recombination would assist the overall circulation. In this way, the hydrogen would be removed as close as possible to the source, thereby minimizing the amount of hydrogen immediately downstream of the source and reducing the hydrogen concentration to acceptable levels at other locations. Such a strategy requires the containment volume to be divided into an upflow path, past the hydrogen source and the recombiner, and a downflow path to complete the circuit. The flow could be generated actively using fans or passively using buoyancy forces arising from the difference in density of gases in the upfiow and downflow paths; the gases in the downflow path being cooled at an elevated heat sink. (author)

Helium-3 and helium-4 acceleration by high power laser pulses for hadron therapy

Directory of Open Access Journals (Sweden)

S. S. Bulanov

2015-06-01

Full Text Available The laser driven acceleration of ions is considered a promising candidate for an ion source for hadron therapy of oncological diseases. Though proton and carbon ion sources are conventionally used for therapy, other light ions can also be utilized. Whereas carbon ions require 400 MeV per nucleon to reach the same penetration depth as 250 MeV protons, helium ions require only 250 MeV per nucleon, which is the lowest energy per nucleon among the light ions (heavier than protons. This fact along with the larger biological damage to cancer cells achieved by helium ions, than that by protons, makes this species an interesting candidate for the laser driven ion source. Two mechanisms (magnetic vortex acceleration and hole-boring radiation pressure acceleration of PW-class laser driven ion acceleration from liquid and gaseous helium targets are studied with the goal of producing 250 MeV per nucleon helium ion beams that meet the hadron therapy requirements. We show that He^{3} ions, having almost the same penetration depth as He^{4} with the same energy per nucleon, require less laser power to be accelerated to the required energy for the hadron therapy.

Superfluid helium at subcritical active core

International Nuclear Information System (INIS)

Vasil'ev, V.V.; Lopatkin, A.V.; Muratov, V.G.; Rakhno, I.L.

2002-01-01

Power range and neutron flux wherein super thermal source was realized at high volume of superfluid helium were investigated. MCU, BRAND, MCNP codes were used for the calculation of reactors. It is shown that the availability of full-size diameter for cryogenic source of ultracold neutrons, as the source with superfluid helium is considered, is possible in the reflector of subcritical assembly. Results obtained from the MCNP-4B code application demonstrated that the density of thermal neutron flux in helium must be not higher than 2.3 x 10 11 s -1 cm -2 [ru

On the Spectral Evolution of Helium-atmosphere White Dwarfs Showing Traces of Hydrogen

Science.gov (United States)

Rolland, B.; Bergeron, P.; Fontaine, G.

2018-04-01

We present a detailed spectroscopic analysis of 115 helium-line (DB) and 28 cool, He-rich hydrogen-line (DA) white dwarfs based on atmosphere fits to optical spectroscopy and photometry. We find that 63% of our DB population show hydrogen lines, making them DBA stars. We also demonstrate the persistence of pure DB white dwarfs with no detectable hydrogen feature at low effective temperatures. Using state-of-the art envelope models, we next compute the total quantity of hydrogen, M H, that is contained in the outer convection zone as a function of effective temperature and atmospheric H/He ratio. We find that some (T eff, M H) pairs cannot physically exist as a homogeneously mixed structure; such a combination can only occur as stratified objects of the DA spectral type. On that basis, we show that the values of M H inferred for the bulk of the DBA stars are too large and incompatible with the convective dilution scenario. We also present evidence that the hydrogen abundances measured in DBA and cool, helium-rich white dwarfs cannot be globally accounted for by any kind of accretion mechanism onto a pure DB star. We suggest that cool, He-rich DA white dwarfs are most likely created by the convective mixing of a DA star with a thin hydrogen envelope; they are not cooled down DBAs. We finally explore several scenarios that could account for the presence of hydrogen in DBA stars.

Helium leak testing methods in nuclear applications

International Nuclear Information System (INIS)

Ahmad, Anis

2004-01-01

Helium mass-spectrometer leak test is the most sensitive leak test method. It gives very reliable and sensitive test results. In last few years application of helium leak testing has gained more importance due to increased public awareness of safety and environment pollution caused by number of growing chemical and other such industries. Helium leak testing is carried out and specified in most of the critical area applications like nuclear, space, chemical and petrochemical industries

Pressurized-helium breakdown at very low temperatures

Energy Technology Data Exchange (ETDEWEB)

Metas, R J

1972-06-01

An investigation of the electrical-breakdown behavior of helium at very low temperatures has been carried out to assist the design and development of superconducting power cables. At very high densities, both liquid and gaseous helium showed an enhancement in electric strength when pressurized to a few atmospheres; conditioned values of breakdown fields then varied between 30 and 45 MV/m. Breakdown processes occurring over a wide range of helium densities are discussed. 24 references.

The measurement of mass spectrometric peak height ratio of helium isotope in trace samples

International Nuclear Information System (INIS)

Sun Mingliang

1989-01-01

An experiment study on the measurement of mass spectrometric peak height ratio of helium isotope in the trace gaseous sample is discussed by using the gas purification line designed by the authors and model VG-5400 static-vacuum noble gas mass spectrometer imported and air helium as a standard. The results show that the amount of He and Ne in natural gas sample is 99% after purification. When the amount of He in Mass Spectrometer is more than 4 x 10 -7 cm 3 STP, it's sensitivity remains stable, about 10 -4 A/cm 3 STP He and the precision of 3 He/ 4 He ratio within the following 17 days is 1.32%. The 'ABA' pattern and experiment condition in the measurement of mass spectrometric peak height ratio of He isotope are presented

Dipole moments of molecules solvated in helium nanodroplets

International Nuclear Information System (INIS)

Stiles, Paul L.; Nauta, Klaas; Miller, Roger E.

2003-01-01

Stark spectra are reported for hydrogen cyanide and cyanoacetylene solvated in helium nanodroplets. The goal of this study is to understand the influence of the helium solvent on measurements of the permanent electric dipole moment of a molecule. We find that the dipole moments of the helium solvated molecules, calculated assuming the electric field is the same as in vacuum, are slightly smaller than the well-known gas-phase dipole moments of HCN and HCCCN. A simple elliptical cavity model quantitatively accounts for this difference, which arises from the dipole-induced polarization of the helium

Homologous recombination in hybridoma cells: heavy chain chimeric antibody produced by gene targeting.

OpenAIRE

Fell, H P; Yarnold, S; Hellström, I; Hellström, K E; Folger, K R

1989-01-01

We demonstrate that murine myeloma cells can efficiently mediate homologous recombination. The murine myeloma cell line J558L was shown to appropriately recombine two transfected DNA molecules in approximately 30% of cells that received and integrated intact copies of both molecules. This activity was then exploited to direct major reconstructions of an endogenous locus within a hybridoma cell line. Production of antigen-specific chimeric heavy chain was achieved by targeting the human IgG1 h...

QTL mapping of fruit rot resistance to the plant pathogen Phytophthora capsici in a recombinant inbred line Capsicum annuum population.

Science.gov (United States)

Naegele, R P; Ashrafi, H; Hill, T A; Chin-Wo, S Reyes; Van Deynze, A E; Hausbeck, M K

2014-05-01

Phytophthora capsici is an important pepper (Capsicum annuum) pathogen causing fruit and root rot, and foliar blight in field and greenhouse production. Previously, an F6 recombinant inbred line population was evaluated for fruit rot susceptibility. Continuous variation among lines and partial and isolate-specific resistance were found. In this study, Phytophthora fruit rot resistance was mapped in the same F6 population between Criollo del Morelos 334 (CM334), a landrace from Mexico, and 'Early Jalapeno' using a high-density genetic map. Isolate-specific resistance was mapped independently in 63 of the lines evaluated and the two parents. Heritability of the resistance for each isolate at 3 and 5 days postinoculation (dpi) was high (h(2) = 0.63 to 0.68 and 0.74 to 0.83, respectively). Significant additive and epistatic quantitative trait loci (QTL) were identified for resistance to isolates OP97 and 13709 (3 and 5 dpi) and 12889 (3 dpi only). Mapping of fruit traits showed potential linkage with few disease resistance QTL. The partial fruit rot resistance from CM334 suggests that this may not be an ideal source for fruit rot resistance in pepper.

Commissioning of the helium cryogenic system for the HIE- ISOLDE accelerator upgrade at CERN

International Nuclear Information System (INIS)

Delruelle, N; Inglese, V; Leclercq, Y; Pirotte, O; Williams, L

2015-01-01

The High Intensity and Energy ISOLDE (HIE-ISOLDE) project is a major upgrade of the existing ISOLDE and REX-ISOLDE facilities at CERN. The most significant improvement will come from replacing the existing REX accelerating structure by a superconducting linear accelerator (SC linac) composed ultimately of six cryo-modules installed in series, each containing superconducting RF cavities and solenoids operated at 4.5 K. In order to provide the cooling capacity at all temperature levels between 300 K and 4.5 K for the six cryo-modules, an existing helium refrigerator, manufactured in 1986 and previously used to cool the ALEPH magnet during LEP operation from 1989 to 2000, has been refurbished, reinstalled and recommissioned in a dedicated building located next to the HIE-ISOLDE experimental hall. This helium refrigerator has been connected to a new cryogenic distribution line, consisting of a 30-meter long vacuum-insulated transfer line, a 2000-liter storage dewar and six interconnecting valve boxes, one for each cryo-module. This paper describes the whole cryogenic system and presents the commissioning results including the preliminary operation at 4.5 K of the first cryo- module in the experimental hall. (paper)

Starlight excitation of permitted lines in gaseous nebulae

International Nuclear Information System (INIS)

Grandi, S.A.

1975-01-01

The weak heavy element permitted lines observed in the spectra of gaseous nebula have, with only a few exceptions, been thought to be excited only by recombination. The accuracy of this assumption for individual lines in nebula spectra is investigated in detail via model nebula calculations. First, approximations and techniques of calculation are considered for the three possible excitation mechanisms: recombination, resonance fluorescence by the starlight continuum, and resonance fluorescence by other nebular emission lines. Next, the permitted lines of O I as observed in gaseous nebulae are discussed. Thirdly, it is shown that varying combinations of recombination, resonance fluorescence by starlight, and resonance fluorescence by other nebula lines can successfully account for the observed strengths in the Orion Nebula of lines of the following ions: C II, N I, N II, N III, O II, Ne II, Si II, Si III, and S III. A similar analysis is performed for the lines in the spectra of the planetary nebulae NGC7662 and NGC7027, and, with some exceptions, satisfactory agreement between the observed and predicted line strengths is found. Finally, observations of the far red spectra of the Orion Nebula, the planetary nebulae NGC3242, NGC6210, NGC2392, IC3568, IC4997, NGC7027, and MGC7662, and the reflection nebulae IC431 and NGC2068 are reported

Helium atoms and molecules in strong magnetic fields

Science.gov (United States)

Mori, K.

Recent theoretical studies have shown that the neutron star surface may be composed of helium or heavier elements as hydrogen may be quickly depleted by diffuse nuclear burning Chang Bildsten However while Hydrogen atmospheres have been studied in great details atomic data for helium is available only for He ion Pavlov Bezchastnov 2005 We performed Hartree-Fock type calculation for Helium atom and molecules and computed their binding ionization and dissociation energies in strong magnetic fields B sim10 12 -- 10 15 G We will present ionization balance of Helium atmospheres at typical magnetic field strengths and temperatures to radio-quiet neutron stars and AXPs We will also discuss several implications of helium atmosphere to X-ray data of isolated neutron stars focusing on the detected spectral features

Tritium and helium-3 in metals

International Nuclear Information System (INIS)

Lasser, R.

1989-01-01

The book surveys recent results on the behaviour of tritium and its decay product helium-3 metals. In contrast to many earlier books which discuss the properties of the stable hydrogen isotopes without mentioning tritium, this book reviews mainly the results on tritium in metals. Due to the difficulties in preparing metal tritide samples, very important quantities such as diffusivity, superconductivity, solubility, etc. have only been determined very recently. The book not only presents the measured tritium data, but also the isotopic dependency of the different physical properties by comparing H, D and T results. A chapter is devoted to helium-3 in metals. Aspects such as helium release, generation of helium bubbles, swelling, and change of the lattice parameter upon aging are discussed. The book provides the reader with up-to-date information and deep insight into the behaviour of H, D, T and He-3 in metals. Further important topics such a tritium production, its risks, handling and discharge to the environment are also addressed

Helium cosmic ray flux measurements at Mars

International Nuclear Information System (INIS)

Lee, Kerry; Pinsky, Lawrence; Andersen, Vic; Zeitlin, Cary; Cleghorn, Tim; Cucinotta, Frank; Saganti, Premkumar; Atwell, William; Turner, Ron

2006-01-01

The helium energy spectrum in Martian orbit has been observed by the MARIE charged particle spectrometer aboard the 2001 Mars Odyssey spacecraft. The orbital data were taken from March 13, 2002 to October 28, 2003, at which time a very intense Solar Particle Event caused a loss of communication between the instrument and the spacecraft. The silicon detector stack in MARIE is optimized for the detection of protons and helium in the energy range below 100MeV/n, which typically includes almost all of the flux during SPEs. This also makes MARIE an efficient detector for GCR helium in the energy range of 50-150MeV/n. We will present the first fully normalized flux results from MARIE, using helium ions in this energy range

Helium cosmic ray flux measurements at Mars

Energy Technology Data Exchange (ETDEWEB)

Lee, Kerry [University of Houston, 4800 Calhoun Rd. Houston, TX 77204 (United States)]. E-mail: ktlee@ems.jsc.nasa.gov; Pinsky, Lawrence [University of Houston, 4800 Calhoun Rd. Houston, TX 77204 (United States); Andersen, Vic [University of Houston, 4800 Calhoun Rd. Houston, TX 77204 (United States); Zeitlin, Cary [National Space Biomedical Research Institute, Baylor College of Medicine, Houston, TX (United States); Cleghorn, Tim [NASA Johnson Space Center, 2101 NASA Road 1, Houston, TX 77058 (United States); Cucinotta, Frank [NASA Johnson Space Center, 2101 NASA Road 1, Houston, TX 77058 (United States); Saganti, Premkumar [Prairie View A and M University, P.O. Box 519, Prairie View, TX 77446-0519 (United States); Atwell, William [The Boeing Company, Houston, TX (United States); Turner, Ron [Advancing National Strategies and Enabling Results (ANSER), Arlington, Virginia (United States)

2006-10-15

The helium energy spectrum in Martian orbit has been observed by the MARIE charged particle spectrometer aboard the 2001 Mars Odyssey spacecraft. The orbital data were taken from March 13, 2002 to October 28, 2003, at which time a very intense Solar Particle Event caused a loss of communication between the instrument and the spacecraft. The silicon detector stack in MARIE is optimized for the detection of protons and helium in the energy range below 100MeV/n, which typically includes almost all of the flux during SPEs. This also makes MARIE an efficient detector for GCR helium in the energy range of 50-150MeV/n. We will present the first fully normalized flux results from MARIE, using helium ions in this energy range.

Experimental evolution of recombination and crossover interference in Drosophila caused by directional selection for stress-related traits.

Science.gov (United States)

Aggarwal, Dau Dayal; Rashkovetsky, Eugenia; Michalak, Pawel; Cohen, Irit; Ronin, Yefim; Zhou, Dan; Haddad, Gabriel G; Korol, Abraham B

2015-11-27

Population genetics predicts that tight linkage between new and/or pre-existing beneficial and deleterious alleles should decrease the efficiency of natural selection in finite populations. By decoupling beneficial and deleterious alleles and facilitating the combination of beneficial alleles, recombination accelerates the formation of high-fitness genotypes. This may impose indirect selection for increased recombination. Despite the progress in theoretical understanding, interplay between recombination and selection remains a controversial issue in evolutionary biology. Even less satisfactory is the situation with crossover interference, which is a deviation of double-crossover frequency in a pair of adjacent intervals from the product of recombination rates in the two intervals expected on the assumption of crossover independence. Here, we report substantial changes in recombination and interference in three long-term directional selection experiments with Drosophila melanogaster: for desiccation (~50 generations), hypoxia, and hyperoxia tolerance (>200 generations each). For all three experiments, we found a high interval-specific increase of recombination frequencies in selection lines (up to 40-50% per interval) compared to the control lines. We also discovered a profound effect of selection on interference as expressed by an increased frequency of double crossovers in selection lines. Our results show that changes in interference are not necessarily coupled with increased recombination. Our results support the theoretical predictions that adaptation to a new environment can promote evolution toward higher recombination. Moreover, this is the first evidence of selection for different recombination-unrelated traits potentially leading, not only to evolution toward increased crossover rates, but also to changes in crossover interference, one of the fundamental features of recombination.

Leak-tightness assessment of demountable joints for the super fluid helium system of the CERN Large Hadron Collider (LHC)

International Nuclear Information System (INIS)

Brunet, J.C.; Poncet, A.; Trilhe, P.

1994-01-01

The future high energy accelerator LHC presently considered at CERN, will make heavy use of demountable cryogenic joints operating at superfluid helium temperatures (1.8 K). These joints will be required for connecting the cryomagnets to their feeding lines, helium safety valves to cold masses, both on their measuring benches and eventually in their final installation set-up. The very large size of the future machine and, consequently, the large number of cryogenic joints imply that their reliability in leak tightness be very high, in particular after extreme loading conditions such as the high helium pressures resulting from superconducting magnet quenches. For these reasons, a test set-up has been especially built at CERN to reproduce these conditions, and to assess the leak tightness reliability of commercially available joints. A description of the facility is presented, together with the first test results

Atomistic simulation of helium bubble nucleation in palladium

Energy Technology Data Exchange (ETDEWEB)

Wang Liang [Department of Applied Physics, Hunan University, Changsha 410082 (China); Hu, Wangyu [Department of Applied Physics, Hunan University, Changsha 410082 (China)], E-mail: wangyuhu2001cn@yahoo.com.cn; Xiao Shifang [Department of Applied Physics, Hunan University, Changsha 410082 (China)], E-mail: sfxiao@yahoo.com.cn; Yang Jianyu [Department of Maths and Physics, Hunan Institute of Engineering, Xiangtan 411104 (China); Deng Huiqiu [Department of Applied Physics, Hunan University, Changsha 410082 (China)

2009-09-15

A palladium crystal has been constructed with 11808 atoms. 55 helium atoms occupied the octahedral position of palladium crystal are introduced and retained in a spherical region. Molecular dynamic simulations are performed in a constant temperature and constant volume ensemble (NVT) with temperature controlled by Nose-Hoover thermostat. The interactions between palladium atoms are described with modified analytic embedded atom method (MAEAM), the interactions between palladium atom and helium atom are in the form of Morse potential, and the interactions between helium atoms are in the form of L-J potential function. With the analysis of the radial distribution function (RDF) and microstructure, it reveals that some of helium atoms form a series of clusters with different size, and the nucleation core is random at low temperature, and which is the embryo of helium bubble. Increasing temperature can accelerate the process of bubble nucleation, and the clusters will aggregate and coalesce into a bigger one in which there are no palladium atoms, and it is considered as a helium bubble.

Effects of recombinant human epidermal growth factor on the proliferation and radiation survival of human fibroblast cell lines in vitro

International Nuclear Information System (INIS)

Kim, Hyun Sook; Kang, Ki Mun; Na, Jae Boem; Chai, Gyu Young; Lee, Sang Wook

2006-01-01

To explore the effect of recombinant human EGF on the proliferation and survival of human fibroblast cell lines following irradiation. Fibroblast was originated human skin and primary cultured. The trypan blue stain assay and MTT assay were used to study the proliferative effects of EGF on human fibroblast cell lines in vitro. An incubation of fibroblasts with rhEGF for 24 hours immediately after irradiation was counted everyday. Cell cycle distributions were analyzed by FACS analysis. Number of fibroblast was significant more increased rhEGF (1.0 nM, 10 nM, 100 nM, 1,000 nM) treated cell than control after 8 Gy irradiation. Most effective dose of rhEGF was at 160 nM. These survival differences were maintained at 1 week later. Proportion of S phase was significantly increased on rhEGF treated cells. rhEGF cause increased fibroblast proliferation following irradiation. We expect that rhEGF was effective for radiation induced wound healing

Helium-Charged La-Ni-Al Thin Films Deposited by Magnetron Sputtering

International Nuclear Information System (INIS)

Shi Liqun; Chen Deming; Xu Shilin; Liu Chaozhu; Hao Wanli; Zhou Zhuyin

2005-01-01

An advanced implantation of low energy helium-4 atoms during the La-Ni-Al film growth by adopting magnetron sputtering with Ar/He mixture gases is discussed. Both proton backscattering spectroscopy (PBS) and elastic recoil detection (ERD) analyses were adopted to measure helium concentration of the films and distribution in the near-surface region. Helium atoms with a high concentration incorporate evenly in deposited film. The introduction of the helium with no extra irradiation damage is expected by choosing suitable deposition conditions. It was found that amorphous and crystalline LaNi 5 -type structures can be achieved when sputtered with pure Ar and Ar/He mixture gases at room temperature, respectively. Thermal desorption experiments proposes that a part of hydrogen atoms are bound to trapped helium at crystal and releases together with helium. Only a small fraction of helium is released from the helium-vacancy clusters in lower temperature range and most of helium is released from small size helium bubbles in the high temperature range

Evolution of helium stars: a self-consistent determination of the boundary of a helium burning convective core

International Nuclear Information System (INIS)

Savonije, G.J.; Takens, R.J.

1976-01-01

A generalization of the Henyey-scheme is given that introduces the mass of the convective core and the density at the outer edge of the convective core boundary as unknowns which have to be solved simultaneously with the other unknowns. As a result, this boundary is determined in a physically self-consistent way for expanding as well as contracting cores, i.e. during the Henyey iterative cycle; its position becomes consistent with the overall physical structure of the star, including the run of the chemical abundances throughout the star. Using this scheme, the evolution of helium stars was followed up to carbon ignition for a number of stellar masses. As compared with some earlier investigations, the calculations show a rather large increase in mass of the convective cores during core helium burning. Evolutionary calculations for a 2M(sun) helium star show that the critical mass for which a helium star ignites carbon non-degenerately lies near 2M(sun). (orig.) [de

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.

Use of Al XII and Mg XI lines as solar plasma diagnostics

International Nuclear Information System (INIS)

Bromage, B.J.I.; Phillips, K.J.H.; Keenan, F.P.; McCann, S.M.

1989-09-01

We present three sets of observations of n=1 to n=2 lines due to helium-like aluminium (Al XII), made during two solar flares (25 August, 1980 and 19 October, 1986), using the X-ray Polychromator on satellite. The observed temperature-sensitive line ratio G is shown to be consistent with previously observed close-coupling calculations, although the ratio R, which is both temperature and density-sensitive for lower-Z elements, is not sufficiently well determined from these data to say more than that the observed values of R are not inconsistent with the theoretical calculations. This region of the spectrum also includes the helium-like magnesium (Mg XI) 1 1 S-3 1 P line, and it is shown that the ratio of this line to the Al XII resonance (1 1 S-2 1 P) line is a more sensitive indicator of electron temperature than are the Al XII G and R ratios. We demonstrate that the three ratios may be used together in order to derive values of emission measure, electron temperature and electron density during these flares. (author)

Liquid-helium scintillation detection with germanium photodiodes

International Nuclear Information System (INIS)

Luke, P.N.; Haller, E.E.; Steiner, H.M.

1982-05-01

Special high-purity germanium photodiodes have been developed for the direct detection of vacuum ultraviolet scintillations in liquid helium. The photodiodes are immersed in the liquid helium, and scintillations are detected through one of the bare sides of the photodiodes. Test results with scintillation photons produced by 5.3-MeV α particles are presented. The use of these photodiodes as liquid-helium scintillation detectors may offer substantial improvements over the alternate detection method requiring the use of wavelength shifters and photomultiplier tubes

Helium release from metals with face-centered cubic structure

International Nuclear Information System (INIS)

Sciani, V.; Lucki, G.; Jung, P.

1984-01-01

The helium release from gold sheets of 5 and 54 μm of thickness and helium concentrations from 10 -9 to 10 -5 ap of He during the isothermal and linear annealing is studied. The helium was put in the sample through the implantation of alpha particles, with variable energy,in the cyclotron. The free diffusion of the atoms of the helium, where the diffusion coefficient follows an Arrhenius law is studied. (E.G.) [pt

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

Simplicity works for superfluid helium

International Nuclear Information System (INIS)

Bowley, Roger

2000-01-01

The famous philosopher Karl Popper once said that ''science is the art of systematic oversimplification''. Indeed, when faced with a new puzzle the trick is to simplify it without losing the essential physics - something that is easier said than done. However, this approach has paid off recently in low-temperature physics. Last year Richard Packard, Seamus Davis and co-workers at the University of California at Berkeley encountered a puzzling new phenomenon in superfluid helium-3, a quantum fluid that remains a liquid close to absolute zero and exhibits unusual properties such as the ability to flow without friction (A Machenkov et al. 1999 Phys. Rev. Lett. 83 3860). Previous experiments had revealed that certain effects in liquid helium are analogous to effects observed in superconductors, materials that lose all resistance to electric current at low temperatures. When the Berkeley researchers connected two reservoirs of superfluid helium-3, the superfluid flowed back and forth through apertures that formed a ''weak link'' between the two containers. This behaviour is similar to the oscillatory current of electrons that can flow across an insulating gap separating two superconductors - a device that is known as a Josephson junction. What was puzzling about the Berkeley results was that the helium-3 had two different stable configurations, both of which behaved in an unconventional way compared with a Josephson junction. This puzzle has now been solved independently by Sidney Yip at the National Center for Theoretical Sciences in Taiwan, and by Janne Viljas and Erkki Thuneberg at the Helsinki University of Technology in Finland (Phys. Rev. Lett. 1999 83 3864 and 3868). In this article the author describes the latest research on superfluid helium. (UK)

A Glance at Recombination Hotspots in the Domestic Cat.

Directory of Open Access Journals (Sweden)

Hasan Alhaddad

Full Text Available Recombination has essential roles in increasing genetic variability within a population and in ensuring successful meiotic events. The objective of this study is to (i infer the population-scaled recombination rate (ρ, and (ii identify and characterize regions of increased recombination rate for the domestic cat, Felis silvestris catus. SNPs (n = 701 were genotyped in twenty-two East Asian feral cats (random bred. The SNPs covered ten different chromosomal regions (A1, A2, B3, C2, D1, D2, D4, E2, F2, X with an average region size of 850 Kb and an average SNP density of 70 SNPs/region. The Bayesian method in the program inferRho was used to infer regional population recombination rates and hotspots localities. The regions exhibited variable population recombination rates and four decisive recombination hotspots were identified on cat chromosome A2, D1, and E2 regions. As a description of the identified hotspots, no correlation was detected between the GC content and the locality of recombination spots, and the hotspots enclosed L2 LINE elements and MIR and tRNA-Lys SINE elements.

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)

Chemical composition and effective temperatures of metallic line white dwarfs

International Nuclear Information System (INIS)

Hammond, G.L.

1974-01-01

Model atmosphere techniques have been employed to determine the composition, effective temperatures, radii, masses and surface gravities of white dwarfs Ross 640 and van Maanen 2. The non-gray, LTE, convective, constant flux models employed collisional damping constants for the Ca II H and K lines that were measured in a laboratory device that simulated white dwarf atmospheric conditions. Ross 640 was found to have an extremely helium-rich composition and T/sub eff/ = 8500K, while the observed properties of van Maanen 2 were fitted best by a model with 91 percent helium, 9 percent hydrogen and T/sub eff/ = 6100K. The laboratory measurements of pressure shifts for the Ca II lines casts some doubt on the interpretation of recent radial velocity determinations for van Maanen 2. (U.S.)

Developing baculovirus-insect cell expression systems for humanized recombinant glycoprotein production

International Nuclear Information System (INIS)

Jarvis, Donald L.

2003-01-01

The baculovirus-insect cell expression system is widely used to produce recombinant glycoproteins for many different biomedical applications. However, due to the fundamental nature of insect glycoprotein processing pathways, this system is typically unable to produce recombinant mammalian glycoproteins with authentic oligosaccharide side chains. This minireview summarizes our current understanding of insect protein glycosylation pathways and our recent efforts to address this problem. These efforts have yielded new insect cell lines and baculoviral vectors that can produce recombinant glycoproteins with humanized oligosaccharide side chains

The problem of helium in structural materials for fusion reactor

International Nuclear Information System (INIS)

Nikiforov, A.S.; Zakharov, A.P.; Chuev, V.I.

1982-01-01

The processes of helium buildup in some metals and alloys at different energy neutron flux irradiation under thermonuclear reactor conditions are considered. The data on high temperature helium embrittlement of a number of stainless steels, titanium and aluminium alloys etc. are given A review of experiments concerning the implanted helium behaviour is presented. Possible reactions between helium atoms and point defects or their clusters are discussed. Analysed are material structure variations upon buildup in them up to 1 at % of helium

Pierre Gorce working on a helium pump.

CERN Multimedia

1975-01-01

This type of pump was designed by Mario Morpurgo, to circulate liquid helium in superconducting magnets wound with hollow conductors. M. Morpurgo, Design and construction of a pump for liquid helium, CRYIOGENICS, February 1977, p. 91

Helium solubility and bubble growth in metals under high pressure

International Nuclear Information System (INIS)

Laakmann, J.

1985-07-01

Helium solubility and bubble growth in metals under high pressure polycrystals and single crystals of gold were heated in helium at temperatures between 475 K and 1250 K in a pressure regime of 200 to 2700 bar to measure the solubility of helium in gold. After quenching to room temperature the helium content, measured by mass spectrometry, showed the following properties: 1) A linear dependence of the He solubility on pressure. 2) Thinning of the specimen reduces the helium content by a factor 10 to 100 but does not change the linear pressure dependence. 3) The thermal release of He from thinned polycrystals and single crystals occurs mainly in a single peak at 500 K. 4) The He concentration of the thinned single crystals was lower by a factor of 10 to 50 than that of the thinned polycrystals. 5) The He solubility in single crystals can be described by an enthalpy of solution Hsub(s)sup(f) = 0.85 +- 0.7 eV and a non-configurational entropy of Ssub(s)sup(f) between 0 k and 1 k (k: Boltzmann-constant). In order to measure the pressure dependence of helium bubble growth in nickel polycrystal Ni-foils were α-implanted to a helium content of 130 appm. The evaluation of the size distribution of the helium bubbles after heat treatments shows 1) The helium content of the observable bubbles - assumed to be in equilibrium - equals the amount of helium implanted into the specimen. 2) The activation energy for the growth of helium bubbles is 1.25 +- 0.3 eV. The comparison of specimen which had been heated at low pressures up to 10 bar with others heated at 2500-2700 bar does not show an unequivocal pressure dependence for helium bubble growth. (orig./IHOE) [de

Helium effect on mechanical property of fusion reactor structural materials

International Nuclear Information System (INIS)

Yamamoto, Norikazu; Chuto, Toshinori; Murase, Yoshiharu; Nakagawa, Johsei

2004-01-01

High-energy neutrons produced in fusion reactor core caused helium in the structural materials of fusion reactors, such as blankets. We injected alpha particles accelerated by the cyclotron to the samples of martensite steel (9Cr3WVTaB). Equivalent helium doses injected to the sample is estimated to be up to 300 ppm, which were estimated to be equivalent to helium accumulation after the 1-year reactor operation. Creep tests of the samples were made to investigate helium embrittlement. There were no appreciable changes in the relation between the stresses and the rupture time, the minimum creep rate and the applied stress. Grain boundary effect by helium was not observed in ruptured surfaces. Fatigue tests were made for SUS304 samples, which contain helium up to 150 ppm. After 0.05 Hz cyclic stress tests, it was shown that the fatigue lifetime (cycles to rupture and extension to failure) are 1/5 in 150 ppm helium samples compared with no helium samples. The experimental results suggest martensite steel is promising for structural materials of fusion reactors. (Y. Tanaka)

Adsorption pump for helium pumping out

International Nuclear Information System (INIS)

Donde, A.L.; Semenenko, Yu.E.

1981-01-01

Adsorption pump with adsorbent cooling by liquid helium is described. Shuttered shield protecting adsorbent against radiation is cooled with evaporating helium passing along the coil positioned on the shield. The pump is also equipped with primed cylindrical shield, cooled with liquid nitrogen. The nitrogen shield has in the lower part the shuttered shield, on the pump casing there is a valve used for pump pre-burning, and valves for connection to recipient as well. Pumping- out rates are presented at different pressures and temperatures of adsorbent. The pumping-out rate according to air at absorbent cooling with liquid nitrogen constituted 5x10 -4 Pa-3000 l/s, at 2x10 -2 Pa-630 l/s. During the absorbent cooling with liquid hydrogen the pumping-out rate according to air was at 4x10 -4 Pa-580 l/s, at 2x10 -3 Pa-680 l/s, according to hydrogen - at 8x10 -5 Pa-2500 l/s, at 5x10 -3 Pa-4200 l/s. During adsorbent cooling with liquid helium the rate of pumping-out according to hydrogen at 3x10 5 Pa-2400% l/s, at 6x10 3 Pa-1200 l/s, and according to helium at 3.5x10 -5 Pa-2800 l/s, at 4x10 -3 Pa-1150 l/s. The limit vacuum is equal to 1x10 -7 Pa. The volume of the vessel with liquid helium is equal to 3.5 l. Helium consumption is 80 cm 3 /h. Consumption of liquid nitrogen from the shield is 400 cm 3 /h. The limit pressure in the pump is obtained after forevacuum pumping-out (adsorbent regeneration) at 300 K temperature. The pump is made of copper. The pump height together with primed tubes is 800 mm diameter-380 mm [ru

Blackbody-radiation correction to the polarizability of helium

International Nuclear Information System (INIS)

Puchalski, M.; Jentschura, U. D.; Mohr, P. J.

2011-01-01

The correction to the polarizability of helium due to blackbody radiation is calculated near room temperature. A precise theoretical determination of the blackbody radiation correction to the polarizability of helium is essential for dielectric gas thermometry and for the determination of the Boltzmann constant. We find that the correction, for not too high temperature, is roughly proportional to a modified hyperpolarizability (two-color hyperpolarizability), which is different from the ordinary hyperpolarizability of helium. Our explicit calculations provide a definite numerical result for the effect and indicate that the effect of blackbody radiation can be excluded as a limiting factor for dielectric gas thermometry using helium or argon.

Tritium Decay Helium-3 Effects in Tungsten

Energy Technology Data Exchange (ETDEWEB)

Shimada, M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Merrill, B. J. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2016-06-01

A critical challenge for long-term operation of ITER and beyond to a Demonstration reactor (DEMO) and future fusion reactor will be the development of plasma-facing components (PFCs) that demonstrate erosion resistance to steady-state/transient heat fluxes and intense neutral/ion particle fluxes under the extreme fusion nuclear environment, while at the same time minimizing in-vessel tritium inventories and permeation fluxes into the PFC’s coolant. Tritium will diffuse in bulk tungsten at elevated temperatures, and can be trapped in radiation-induced trap site (up to 1 at. % T/W) in tungsten [1,2]. Tritium decay into helium-3 may also play a major role in microstructural evolution (e.g. helium embrittlement) in tungsten due to relatively low helium-4 production (e.g. He/dpa ratio of 0.4-0.7 appm [3]) in tungsten. Tritium-decay helium-3 effect on tungsten is hardly understood, and its database is very limited. Two tungsten samples (99.99 at. % purity from A.L.M.T. Co., Japan) were exposed to high flux (ion flux of 1.0x1022 m-2s-1 and ion fluence of 1.0x1026 m-2) 0.5%T2/D2 plasma at two different temperatures (200, and 500°C) in Tritium Plasma Experiment (TPE) at Idaho National Laboratory. Tritium implanted samples were stored at ambient temperature in air for more than 3 years to investigate tritium decay helium-3 effect in tungsten. The tritium distributions on plasma-exposed was monitored by a tritium imaging plate technique during storage period [4]. Thermal desorption spectroscopy was performed with a ramp rate of 10°C/min up to 900°C to outgas residual deuterium and tritium but keep helium-3 in tungsten. These helium-3 implanted samples were exposed to deuterium plasma in TPE to investigate helium-3 effect on deuterium behavior in tungsten. The results show that tritium surface concentration in 200°C sample decreased to 30 %, but tritium surface concentration in 500°C sample did not alter over the 3 years storage period, indicating possible tritium

Atmospheric helium and geomagnetic field reversals.

Science.gov (United States)

Sheldon, W. R.; Kern, J. W.

1972-01-01

The problem of the earth's helium budget is examined in the light of recent work on the interaction of the solar wind with nonmagnetic planets. It is proposed that the dominant mode of helium (He4) loss is ion pumping by the solar wind during geomagnetic field reversals, when the earth's magnetic field is very small. The interaction of the solar wind with the earth's upper atmosphere during such a period is found to involve the formation of a bow shock. The penetration altitude of the shock-heated solar plasma is calculated to be about 700 km, and ionization rates above this level are estimated for a cascade ionization (electron avalanche) process to average 10 to the 9th power ions/sq cm/sec. The calculated ionization rates and the capacity of the solar wind to remove ionized helium (He4) from the upper atmosphere during geomagnetic dipole reversals are sufficient to yield a secular equilibrium over geologic time scales. The upward transport of helium from the lower atmosphere under these conditions is found to be adequate to sustain the proposed loss rate.

Diffusion of helium in the Sun

Energy Technology Data Exchange (ETDEWEB)

Noerdlinger, P D [Michigan State Univ., East Lansing (USA). Dept. of Astronomy and Astrophysics; Amsterdam Univ. (Netherlands). Sterrenkundig Instituut)

1977-05-01

I have reduced the set of diffusion and flow equations developed by Burgers for a multi-component gas to a workable scheme for the actual evaluation of the relative diffusion of hydrogen and helium in stars. Previous analyses have used the Aller and Chapman equations, which apply only to trace constitutents and whose coefficients are not believed to be as accurate as Burgers'. Furthermore, the resulting equations have been combined consistently with Paczynski's stellar evolution code to demonstrate small but significant effects in the Sun, from the thermal and gravitational settling of Helium. The core helium content of a 1 M star goes up about 0.04 and the surface helium content down by about -0.03 in 4.5 10/sup 9/ years. The results are still somewhat uncertain because of uncertainties in the underlying plasma physics, and further research is suggested. In any case, the diffusion process speeds up with time, due to increased temperature gradient, and it will be of interest to follow the process in older stars and in later stellar evolution.

Antiprotonic helium atomcules

Directory of Open Access Journals (Sweden)

Sauge Sébastien

2012-10-01

Full Text Available About 3% of antiprotons ( stopped in helium are long-lived with microsecond lifetimes, against picoseconds in all other materials. This unusual longevity has been ascribed to the trapping of on metastable bound states in He+ helium atom-molecules thus named atomcules. Apart from their unique dual structure investigated by laser spectroscopy – a near-circular quasi-classical Rydberg atom with l ~ n – 1 ~ 37 or a special diatomic molecule with a negatively charged nucleus in high rotational state with J = l – the chemical physics aspects of their interaction with other atoms or molecules constitute an interesting topic for molecular physics. While atomcules may resist to million collisions in helium, molecular contaminants such as H2 are likely to destroy them in a single one, down to very low temperatures. In the Born-Oppenheimer framework, we interpret the molecular interaction obtained by ab initio quantum chemical calculations in terms of classical reactive channels, with activation barriers accounting for the experiments carried out in He and H2. From classical trajectory Monte Carlo simulations, we show that the thermalization stage strongly quenches initial populations, thus reduced to a recovered 3 % trapping fraction. This work illustrates the pertinence of chemical physics concepts to the study of exotic processes involving antimatter. New insights into the physico-chemistry of cold interstellar radicals are anticipated.

Temperature dependent recombination dynamics in InP/ZnS colloidal nanocrystals

Science.gov (United States)

Shirazi, R.; Kopylov, O.; Kovacs, A.; Kardynał, B. E.

2012-08-01

In this letter, we investigate exciton recombination in InP/ZnS core-shell colloidal nanocrystals over a wide temperature range. Over the entire range between room temperature and liquid helium temperature, multi-exponential exciton decay curves are observed and well explained by the presence of bright and dark exciton states, as well as defect states. Two different types of defect are present: one located at the core-shell interface and the other on the surface of the nanocrystal. Based on the temperature dependent contributions of all four states to the total photoluminescence signal, we estimate that the four states are distributed within a 20 meV energy band in nanocrystals that emit at 1.82 eV.

Superfluid helium-4: An introductory review

International Nuclear Information System (INIS)

Vinen, W.F.

1983-01-01

Helium was first liquefied by Kamerlingh Onnes in Leiden in July 1908, an achievement that followed much careful and painstaking work. On the same day Onnes reduced the temperature of his helium to a value approaching lK, and he must therefore have produced and observed the superfluid phase. These experimental discoveries led very quickly to a series of remarkable theoretical contributions that laid the foundations for all subsequent work. The period since the second world war has of course seen an enormous amount of work on superfluid helium-4. In reviewing it the author tries to see it in terms of two threads: one originating from Landau; the other from London

Realization of mechanical rotation in superfluid helium

Science.gov (United States)

Gordon, E. B.; Kulish, M. I.; Karabulin, A. V.; Matyushenko, V. I.; Dyatlova, E. V.; Gordienko, A. S.; Stepanov, M. E.

2017-09-01

The possibility of using miniaturized low-power electric motors submerged in superfluid helium for organization of rotation inside a cryostat has been investigated. It has been revealed that many of commercial micromotors can operate in liquid helium consuming low power. Turret with 5 sample holders, assembled on the base of stepper motor, has been successfully tested in experiments on the nanowire production in quantized vortices of superfluid helium. Application of the stepper motor made it possible in a single experiment to study the effect of various experimental parameters on the yield and quality of the nanowires. The promises for continuous fast rotation of the bath filled by superfluid helium by using high-speed brushless micromotor were outlined and tested. Being realized, this approach will open new possibility to study the guest particles interaction with the array of parallel linear vortices in He II.

Helium production in mixed spectrum reactor-irradiated pure elements

International Nuclear Information System (INIS)

Kneff, D.W.; Oliver, B.M.; Skowronski, R.P.

1986-01-01

The objectives of this work are to apply helium accumulation neutron dosimetry to the measurement of neutron fluences and energy spectra in mixed-spectrum fission reactors utilized for fusion materials testing, and to measure helium generation rates of materials in these irradiation environments. Helium generation measurements have been made for several Fe, Cu Ti, Nb, Cr, and Pt samples irradiated in the mixed-spectrum High Flux Isotope Reactor (HFIR) and Oak Ridge Research Reactor (ORR) at the Oak Ridge National Laboratory. The results have been used to integrally test the ENDF/B-V Gas Production File, by comparing the measurements with helium generation predictions made by Argonne National Laboratory using ENDF/B-V cross sections and adjusted reactor spectra. The comparisons indicate consistency between the helium measurements and ENDF/B-V for iron, but cross section discrepancies exist for helium production by fast neutrons in Cu, Ti, Nb, and Cr (the latter for ORR). The Fe, Cu, and Ti work updates and extends previous measurements

Interdiffusion of krypton and xenon in high-pressure helium

International Nuclear Information System (INIS)

Campana, R.J.; Jensen, D.D.; Epstein, B.D.; Hudson, R.G.; Baldwin, N.L.

1980-01-01

The interdiffusion of gaseous fission products in high-pressure helium is an important factor in the control of radioactivity in gas-cooled fast breeder reactors (GCFRs). As presently conceived, GCFRs use pressure-equalized and vented fuel in which fission gases released from the solid matrix oxide fuel are transported through the fuel rod interstices and internal fission product traps to the fuel assembly vents, where they are swept away to external traps and storage. Since the predominant transport process under steady-state operating conditions is interdiffusion of gaseous fission products in helium, the diffusion properties of krypton-helium and xenon-helium couples have been measured over the range of GCFR temperature and pressure conditions ( -1 ) and expected temperature dependence to the 1.66 power (Tsup(1.66)) at lower pressures and temperatures. Additional work is in progress to measure the behaviour of the krypton-helium and xenon-helium couples in GCFR fuel rod charcoal delay traps. (author)

High-temperature helium embrittlement (T>=0,45Tsub(M)) of metals

International Nuclear Information System (INIS)

Batfalsky, P.

1984-06-01

High temperature helium embrittlement, swelling and irradiation creep are the main technical problem of fusion reactor materials. The expected helium production will be very high. The helium produced by (n,α)-processes precipitates into helium bubbles because its solubility in solid metals is very low. Under continuous helium production at high temperature and stress the helium bubbles grow and lead to intergranular early failure. Solution annealed foil specimens of austenitic stainless steel AISI 316 were implanted with α-particles: 1. during creep tests at 1023 K (''in-beam'' test) 2. before the creep tests at high temperature (1023 K). The creep tests have been performed within large ranges of test parameter, e.g. applied stress, temperature, helium implantation rate and helium concentration. After the creep tests the microstructure was investigated using scanning (SEM) and transmission (TEM) electron microscopy. All the helium implanted specimens showed high temperature helium embrittlement, i.e. reduction of rupture time tsub(R) and ductility epsilonsub(R) and evidence of intergranular brittle fracture. The ''in-beam'' creep tests showed greater reduction of rupture time tsub(R) and ductility than the preimplanted creep tests. The comparison of this experimentally obtained data with various theoretical models of high temperature helium embrittlement showed that within the investigated parameter ranges the mechanism controlling the life time of the samples is probably the gas driven stable growth of the helium bubbles within the grain boundaries. (orig.)

Line Shape Modeling for the Diagnostic of the Electron Density in a Corona Discharge

Directory of Open Access Journals (Sweden)

Joël Rosato

2017-09-01

Full Text Available We present an analysis of spectra observed in a corona discharge designed for the study of dielectrics in electrical engineering. The medium is a gas of helium and the discharge was performed at the vicinity of a tip electrode under high voltage. The shape of helium lines is dominated by the Stark broadening due to the plasma microfield. Using a computer simulation method, we examine the sensitivity of the He 492 nm line shape to the electron density. Our results indicate the possibility of a density diagnostic based on passive spectroscopy. The influence of collisional broadening due to interactions between the emitters and neutrals is discussed.

Simplicity works for superfluid helium

Energy Technology Data Exchange (ETDEWEB)

Bowley, Roger [University of Nottingham, Nottingham (United Kingdom)

2000-02-01

The famous philosopher Karl Popper once said that ''science is the art of systematic oversimplification''. Indeed, when faced with a new puzzle the trick is to simplify it without losing the essential physics - something that is easier said than done. However, this approach has paid off recently in low-temperature physics. Last year Richard Packard, Seamus Davis and co-workers at the University of California at Berkeley encountered a puzzling new phenomenon in superfluid helium-3, a quantum fluid that remains a liquid close to absolute zero and exhibits unusual properties such as the ability to flow without friction (A Machenkov et al. 1999 Phys. Rev. Lett. 83 3860). Previous experiments had revealed that certain effects in liquid helium are analogous to effects observed in superconductors, materials that lose all resistance to electric current at low temperatures. When the Berkeley researchers connected two reservoirs of superfluid helium-3, the superfluid flowed back and forth through apertures that formed a ''weak link'' between the two containers. This behaviour is similar to the oscillatory current of electrons that can flow across an insulating gap separating two superconductors - a device that is known as a Josephson junction. What was puzzling about the Berkeley results was that the helium-3 had two different stable configurations, both of which behaved in an unconventional way compared with a Josephson junction. This puzzle has now been solved independently by Sidney Yip at the National Center for Theoretical Sciences in Taiwan, and by Janne Viljas and Erkki Thuneberg at the Helsinki University of Technology in Finland (Phys. Rev. Lett. 1999 83 3864 and 3868). In this article the author describes the latest research on superfluid helium. (UK)

Electron temperature determination from the HeI 3889 angstroem and 5016 angstroem line intensities

International Nuclear Information System (INIS)

Brenning, N.

1979-03-01

The possibility of determining electron temperature by helium spectro scopy in low-density (n(sub e) 2 m - ) plasmas is discussed. It is concluded that most lines can only be used at very low densities (n(sub e) 1 m - ) because the line intensities are highly influenced by secondary processes, such as electron impact induced transitions between excited levels or excitations from metastable levels. The density range where measurements are possible can extended if the influence of these secondary processes on the line intensities can be determined. For most helium I lines this is impossible for lack of atomic data. However, there are two exceptions, the 3889 angstroem (3 3 P yields 2 3 S) and the 5016 angstroem (3 1 yields 2 1 S) lines. The influence from secondary processes on these lines is calculated, and methods are developed which can be used for measurement of electron temperatures T(sub e 1 m - . The use of the methods is illustrated by a experiment where they have been successfully applied. (author)

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.

Liquid Metallic Hydrogen II. A Critical Assessment of Current and Primordial Helium Levels in the Sun

Directory of Open Access Journals (Sweden)

Robitaille P.-M.

2013-04-01

Full Text Available Before a solar model becomes viable in astrophysics, one mus t consider how the ele- mental constitution of the Sun was ascertained, especially relative to its principle com- ponents: hydrogen and helium. Liquid metallic hydrogen has been proposed as a solar structural material for models based on condensed matter (e .g. Robitaille P.-M. Liq- uid Metallic Hydrogen: A Building Block for the Liquid Sun. Progr. Phys. , 2011, v. 3, 60–74. There can be little doubt that hydrogen plays a d ominant role in the uni- verse and in the stars; the massive abundance of hydrogen in t he Sun was established long ago. Today, it can be demonstrated that the near isointe nse nature of the Sun’s Balmer lines provides strong confirmatory evidence for a dis tinct solar surface. The situation relative to helium remains less conclusive. Stil l, helium occupies a prominent role in astronomy, both as an element associated with cosmol ogy and as a byproduct of nuclear energy generation, though its abundances within the Sun cannot be reliably estimated using theoretical approaches. With respect to th e determination of helium lev- els, the element remains spectroscopically silent at the le vel of the photosphere. While helium can be monitored with ease in the chromosphere and the prominences of the corona using spectroscopic methods, these measures are hig hly variable and responsive to elevated solar activity and nuclear fragmentation. Dire ct assays of the solar winds are currently viewed as incapable of providing definitive in formation regarding solar helium abundances. As a result, insight relative to helium r emains strictly based on the- oretical estimates which couple helioseismological appro aches to metrics derived from solar models. Despite their “state of the art” nature, heliu m estimates based on solar models and helioseismology are suspect on several fronts, i ncluding their reliance on solar opacities. The best knowledge can only come from the so

Recombinant FSH versus urinary gonadotrophins or recombinant FSH for ovulation induction in subfertility associated with polycystic ovary syndrome

NARCIS (Netherlands)

Bayram, N.; van Wely, M.; van der Veen, F.

2001-01-01

BACKGROUND: Over the last four decades, various urinary FSH (uFSH) products of different purity have been developed. In 1988 recombinant FSH (rFSH ) was prepared by transfecting Chinese hamster ovary cell lines with both FSH subunit genes. Both rFSH and uFSH are known to be effective in inducing

Born-Mayer type molybdenum-helium and helium-helium interaction potentials, fitted to the results of the helium desorption experiments

International Nuclear Information System (INIS)

Heugten, W.F.W.M. van; Veen, A. van; Caspers, L.M.

1979-01-01

Classes of Born-Mayer type Mo-He and He-He potentials have been derived from helium desorption experiments. The classes are described by linear relations between the Born-Mayer parameters A and b. For computer simulations the Mo-He potential phisub(MoHe)(r)=exp (6.5-3.63 r) and the He-He potential phisub(HeHe)(r)=exp(5.3-5.51 r) are proposed. (Auth.)

Commissioning and Operational Experience with 1 kW Class Helium Refrigerator/Liquefier for SST-1

Science.gov (United States)

Dhard, C. P.; Sarkar, B.; Misra, Ruchi; Sahu, A. K.; Tanna, V. L.; Tank, J.; Panchal, P.; Patel, J. C.; Phadke, G. D.; Saxena, Y. C.

2004-06-01

The helium refrigerator/liquefier (R/L) for the Steady State Super conducting Tokamak (SST-1) has been developed with very stringent specifications for the different operational modes. The total refrigeration capacity is 650 W at 4.5 K and liquefaction capacity of 200 l/h. A cold circulation pump is used for the forced flow cooling of 300 g/s supercritical helium (SHe) for the magnet system (SCMS). The R/L has been designed also to absorb a 200 W transient heat load of the SCMS. The plant consists of a compressor station, oil removal system, on-line purifier, Main Control Dewar (MCD) with associated heat exchangers, cold circulation pump and warm gas management system. An Integrated Flow Control and Distribution System (IFDCS) has been designed, fabricated and installed for distribution of SHe in the toroidal and poloidal field coils as well as liquid helium for cooling of 10 pairs of current leads. A SCADA based control system has been designed using PLC for R/L as well as IFDCS. The R/L has been commissioned and required parameters were achieved confirming to the process. All the test results and commissioning experiences are discussed in this paper.

Neutral helium beam probe

Science.gov (United States)

Karim, Rezwanul

1999-10-01

This article discusses the development of a code where diagnostic neutral helium beam can be used as a probe. The code solves numerically the evolution of the population densities of helium atoms at their several different energy levels as the beam propagates through the plasma. The collisional radiative model has been utilized in this numerical calculation. The spatial dependence of the metastable states of neutral helium atom, as obtained in this numerical analysis, offers a possible diagnostic tool for tokamak plasma. The spatial evolution for several hypothetical plasma conditions was tested. Simulation routines were also run with the plasma parameters (density and temperature profiles) similar to a shot in the Princeton beta experiment modified (PBX-M) tokamak and a shot in Tokamak Fusion Test Reactor tokamak. A comparison between the simulation result and the experimentally obtained data (for each of these two shots) is presented. A good correlation in such comparisons for a number of such shots can establish the accurateness and usefulness of this probe. The result can possibly be extended for other plasma machines and for various plasma conditions in those machines.

Simulation of the Plasma Afterglow in the Discharge Gap of a Subnanosecond Switch Based on an Open Discharge in Helium

Science.gov (United States)

Alexandrov, A. L.; Schweigert, I. V.

2018-05-01

The phenomenon of subnanosecond electrical breakdown in a strong electric field observed in an open discharge in helium at pressures of 6-20 Torr can be used to create ultrafast plasma switches triggering into a conducting state for a time shorter than 1 ns. To evaluate the possible repetition rate of such a subnanosecond switch, it is interesting to study the decay dynamics of the plasma remaining in the discharge gap after ultrafast breakdown. In this paper, a kinetic model based on the particle-in-cell Monte Carlo collision method is used to study the dynamics of the plasma afterglow in the discharge gap of a subnanosecond switch operating with helium at a pressure of 6 Torr. The simulation results show that the radiative, collisional-radiative, and three-body collision recombination mechanisms significantly contribute to the afterglow decay only while the plasma density remains higher than 1012 cm-3; the main mechanism of the further plasma decay is diffusion of plasma particles onto the wall. Therefore, the effect of recombination in the plasma bulk is observed only during the first 10-20 μs of the afterglow. Over nearly the same time, plasma electrons become thermalized. The afterglow time can be substantially reduced by applying a positive voltage U c to the cathode. Since diffusive losses are limited by the ion mobility, the additional ion drift toward the wall significantly accelerates plasma decay. As U c increases from 0 to +500 V, the characteristic time of plasma decay is reduced from 35 to 10 μs.

A DEEPLY ECLIPSING DETACHED DOUBLE HELIUM WHITE DWARF BINARY

International Nuclear Information System (INIS)

Parsons, S. G.; Marsh, T. R.; Gaensicke, B. T.; Drake, A. J.; Koester, D.

2011-01-01

Using Liverpool Telescope+RISE photometry we identify the 2.78 hr period binary star CSS 41177 as a detached eclipsing double white dwarf binary with a 21,100 K primary star and a 10,500 K secondary star. This makes CSS 41177 only the second known eclipsing double white dwarf binary after NLTT 11748. The 2 minute long primary eclipse is 40% deep and the secondary eclipse 10% deep. From Gemini+GMOS spectroscopy, we measure the radial velocities of both components of the binary from the Hα absorption line cores. These measurements, combined with the light curve information, yield white dwarf masses of M 1 = 0.283 ± 0.064 M sun and M 2 = 0.274 ± 0.034 M sun , making them both helium core white dwarfs. As an eclipsing, double-lined spectroscopic binary, CSS 41177 is ideally suited to measuring precise, model-independent masses and radii. The two white dwarfs will merge in roughly 1.1 Gyr to form a single sdB star.

Recombinant Protein Production and Insect Cell Culture and Process

Science.gov (United States)

Spaulding, Glenn F. (Inventor); Goodwin, Thomas J. (Inventor); OConnor, Kim C. (Inventor); Francis, Karen M. (Inventor); Andrews, Angela D. (Inventor); Prewett, Tracey L. (Inventor)

1997-01-01

A process has been developed for recombinant production of selected polypeptides using transformed insect cells cultured in a horizontally rotating culture vessel modulated to create low shear conditions. A metabolically transformed insect cell line is produced using the culture procedure regardless of genetic transformation. The recombinant polypeptide can be produced by an alternative process using virtually infected or stably transformed insect cells containing a gene encoding the described polypeptide. The insect cells can also be a host for viral production.

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)

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.

Application of NIR - CRDS for state selective study of recombination of para and ortho H{sub 3}{sup +} ions with electrons in low temperature plasma

Energy Technology Data Exchange (ETDEWEB)

Varju, J; Roucka, S; KotrIk, T; Plasil, R; Glosik, J, E-mail: Juraj.Glosik@mff.cuni.c [Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holesovickach 2, Prague 8 (Czech Republic)

2010-05-01

We present a study of H{sub 3}{sup +} recombination performed at 77 K on the two lowest rotational levels of this ion, which belong to its two different nuclear spin states of the studied ion. A near infrared cavity ring-down spectrometer ({approx}1381 nm, CRDS arrangement) has been used to obtain the time evolution of concentration of both states. From the overall ion density decay during the afterglow we obtained the binary recombination rate coefficient {alpha}{sub bin} (77 K) = 1.2x10{sup -7} cm{sup 3}s{sup -1}. We have also observed ternary helium assisted recombination of both para and ortho H{sub 3}{sup +}. The process is very slow (at 77 K) and the obtained ternary recombination rate coefficient is in contradiction with the theoretical prediction. It is the first time that the binary and ternary H{sub 3}{sup +} recombination rate coefficient was measured at a known population of para and ortho H{sub 3}{sup +} ions in decaying plasma.

OGLE-2013-SN-079: A LONELY SUPERNOVA CONSISTENT WITH A HELIUM SHELL DETONATION

International Nuclear Information System (INIS)

Inserra, C.; Sim, S. A.; Smartt, S. J.; Nicholl, M.; Jerkstrand, A.; Chen, T.-W.; Wyrzykowski, L.; Fraser, M.; Blagorodnova, N.; Campbell, H.; Shen, K. J.; Gal-Yam, A.; Howell, D. A.; Valenti, S.; Maguire, K.; Mazzali, P.; Bersier, D.; Taubenberger, S.; Benitez-Herrera, S.; Elias-Rosa, N.

2015-01-01

We present observational data for a peculiar supernova discovered by the OGLE-IV survey and followed by the Public ESO Spectroscopic Survey for Transient Objects. The inferred redshift of z = 0.07 implies an absolute magnitude in the rest-frame I-band of M I ∼ –17.6 mag. This places it in the luminosity range between normal Type Ia SNe and novae. Optical and near infrared spectroscopy reveal mostly Ti and Ca lines, and an unusually red color arising from strong depression of flux at rest wavelengths <5000 Å. To date, this is the only reported SN showing Ti-dominated spectra. The data are broadly consistent with existing models for the pure detonation of a helium shell around a low-mass CO white dwarf and ''double-detonation'' models that include a secondary detonation of a CO core following a primary detonation in an overlying helium shell

OGLE-2013-SN-079: A LONELY SUPERNOVA CONSISTENT WITH A HELIUM SHELL DETONATION

Energy Technology Data Exchange (ETDEWEB)

Inserra, C.; Sim, S. A.; Smartt, S. J.; Nicholl, M.; Jerkstrand, A.; Chen, T.-W. [Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN (United Kingdom); Wyrzykowski, L. [University of Warsaw, Astronomical Observatory, Al. Ujazdowskie 400-478 Warszawa (Poland); Fraser, M.; Blagorodnova, N.; Campbell, H. [Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA Cambridge (United Kingdom); Shen, K. J. [Department of Astronomy and Theoretical Astrophysics Center, University of California, Berkeley, CA 94720 (United States); Gal-Yam, A. [Benoziyo Center for Astrophysics, Weizmann Institute of Science, 76100 Rehovot (Israel); Howell, D. A.; Valenti, S. [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102 Goleta, CA 93117 (United States); Maguire, K. [European Southern Observatory for Astronomical Research in the Southern Hemisphere (ESO), Karl-Schwarzschild-Str. 2, 85748 Garching b. Munchen (Germany); Mazzali, P.; Bersier, D. [Astrophysics Research Institute, Liverpool John Moores University, Liverpool (United Kingdom); Taubenberger, S.; Benitez-Herrera, S. [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching (Germany); Elias-Rosa, N., E-mail: c.inserra@qub.ac.uk [INAF - Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, I-35122 Padova (Italy); and others

2015-01-20

We present observational data for a peculiar supernova discovered by the OGLE-IV survey and followed by the Public ESO Spectroscopic Survey for Transient Objects. The inferred redshift of z = 0.07 implies an absolute magnitude in the rest-frame I-band of M{sub I} ∼ –17.6 mag. This places it in the luminosity range between normal Type Ia SNe and novae. Optical and near infrared spectroscopy reveal mostly Ti and Ca lines, and an unusually red color arising from strong depression of flux at rest wavelengths <5000 Å. To date, this is the only reported SN showing Ti-dominated spectra. The data are broadly consistent with existing models for the pure detonation of a helium shell around a low-mass CO white dwarf and ''double-detonation'' models that include a secondary detonation of a CO core following a primary detonation in an overlying helium shell.

Helium Inventory Management For LHC Cryogenics

CERN Document Server

Pyarali, Maisam

2017-01-01

The LHC is a 26.7 km circumference ring lined with superconducting magnets that operate at 1.9 K. These magnets are used to control the trajectory of beams of protons traveling in opposite directions and collide them at various experimental sites across the LHC where their debris is analyzed. The focus of this paper is the cryogenic system that allows the magnets to operate in their superconducting states. It aims to highlight the operating principles of helium refrigeration and liquefaction, with and without nitrogen pre-cooling; discuss the various refrigerators and liquefiers used at CERN for both LHC and Non-LHC applications, with their liquefaction capacities and purposes; and finally to deliberate the management of the LHC inventory and how it contributes to the strategic decision CERN makes regarding the inventory management during the Year-End Technical Stop (YETS), Extended Year-End Technical Stop (EYETS) and long shutdowns.

THE HI INFRARED LINE SPECTRUM FOR BE STARS WITH LOW-DENSITY DISCS

NARCIS (Netherlands)

ZAAL, PA; WATERS, LBFM; MARLBOROUGH, JM

We present theoretical H alpha and HI infrared recombination line calculations for low-density discs around B stars. Such a disc shows no visible emission in H alpha, while the HI IR recombination lines are in emission. This phenomenon has been found in the spectrum of the B0.2V star, tau Sco and

NUCLEAR CONDENSATE AND HELIUM WHITE DWARFS

Energy Technology Data Exchange (ETDEWEB)

Bedaque, Paulo F.; Berkowitz, Evan [Maryland Center for Fundamental Physics, Department of Physics, University of Maryland, College Park, MD (United States); Cherman, Aleksey, E-mail: bedaque@umd.edu, E-mail: evanb@umd.edu, E-mail: a.cherman@damtp.cam.ac.uk [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA (United Kingdom)

2012-04-10

We consider a high-density region of the helium phase diagram, where the nuclei form a Bose-Einstein condensate rather than a classical plasma or a crystal. Helium in this phase may be present in helium-core white dwarfs. We show that in this regime there is a new gapless quasiparticle not previously noticed, arising when the constraints imposed by gauge symmetry are taken into account. The contribution of this quasiparticle to the specific heat of a white dwarf core turns out to be comparable in a range of temperatures to the contribution from the particle-hole excitations of the degenerate electrons. The specific heat in the condensed phase is two orders of magnitude smaller than in the uncondensed plasma phase, which is the ground state at higher temperatures, and four orders of magnitude smaller than the specific heat that an ion lattice would provide, if formed. Since the specific heat of the core is an important input for setting the rate of cooling of a white dwarf star, it may turn out that such a change in the thermal properties of the cores of helium white dwarfs has observable implications.

NUCLEAR CONDENSATE AND HELIUM WHITE DWARFS

International Nuclear Information System (INIS)

Bedaque, Paulo F.; Berkowitz, Evan; Cherman, Aleksey

2012-01-01

We consider a high-density region of the helium phase diagram, where the nuclei form a Bose-Einstein condensate rather than a classical plasma or a crystal. Helium in this phase may be present in helium-core white dwarfs. We show that in this regime there is a new gapless quasiparticle not previously noticed, arising when the constraints imposed by gauge symmetry are taken into account. The contribution of this quasiparticle to the specific heat of a white dwarf core turns out to be comparable in a range of temperatures to the contribution from the particle-hole excitations of the degenerate electrons. The specific heat in the condensed phase is two orders of magnitude smaller than in the uncondensed plasma phase, which is the ground state at higher temperatures, and four orders of magnitude smaller than the specific heat that an ion lattice would provide, if formed. Since the specific heat of the core is an important input for setting the rate of cooling of a white dwarf star, it may turn out that such a change in the thermal properties of the cores of helium white dwarfs has observable implications.

Generation of a tenascin-C-CreER2 knockin mouse line for conditional DNA recombination in renal medullary interstitial cells.

Directory of Open Access Journals (Sweden)

Wenjuan He

Full Text Available Renal medullary interstitial cells (RMIC are specialized fibroblast-like cells that exert important functions in maintaining body fluid homeostasis and systemic blood pressure. Here, we generated a RMIC specific tenascin-C promoter driven inducible CreER2 knockin mouse line with an EGFP reporter. Similar as endogenous tenascin-C expression, the reporter EGFP expression in the tenascin-C-CreER2(+/- mice was observed in the inner medulla of the kidney, and co-localized with COX2 but not with AQP2 or AQP1, suggesting selective expression in RMICs. After recombination (tenascin-C-CreER2(+/-/ROSA26-lacZ(+/- mice + tamoxifen, β-gal activity was restricted to the cells in the inner medulla of the kidney, and didn't co-localize with AQP2, consistent with selective Cre recombinase activity in RMICs. Cre activity was not obvious in other major organs or without tamoxifen treatment. This inducible RMIC specific Cre mouse line should therefore provide a novel tool to manipulate genes of interest in RMICs.

Development of an Agent-based Model to Analyze Contemporary Helium Markets

Energy Technology Data Exchange (ETDEWEB)

Riddle, Matthew E. [Argonne National Lab. (ANL), Argonne, IL (United States); Uckun, Canan [Argonne National Lab. (ANL), Argonne, IL (United States); Conzelmann, Guenter [Argonne National Lab. (ANL), Argonne, IL (United States); Macal, Charles M. [Argonne National Lab. (ANL), Argonne, IL (United States)

2016-02-01

Although U.S. helium demand has remained relatively flat since 2009, exports of helium have increased significantly since then, driven primarily by demand for electronic and semiconductor manufacturing in Asia. In the midst of this global demand shift, the Helium Act dictates a new procedure for pricing and distributing the gas through a reserve that historically functioned as a loose “oligarchy.” The new procedure requires prices to be determined by the open market through auctions and a survey of market prices, as opposed to increasing prices according to the consumer price index. Response to these changes has caused temporary shortages, price increases, and a significant increase in the development of the helium extraction technologies used to produce helium from formerly marginal sources. Technologies are being developed and refined to extract helium from formerly low-yielding natural gas fields containing much lower amounts of helium than the previously considered economic threshold of 0.3%. Combining these transformative policies with the potential for new and significant global supplies from Qatar, Algeria, and Russia could lead to new and unforeseen market behaviors and reactions from global helium markets. The objective of the project is to analyze the global helium markets.

Organ protection by the noble gas helium

NARCIS (Netherlands)

Smit, K.F.

2017-01-01

The aims of this thesis were to investigate whether helium induces preconditioning in humans, and to elucidate the mechanisms behind this possible protection. First, we collected data regarding organ protective effects of noble gases in general, and of helium in particular (chapters 1-3). In chapter

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)

Construction and testing of a double acting bellows liquid helium pump

International Nuclear Information System (INIS)

Burns, W.A.; Green, M.A.; Ross, R.R.; Van Slyke, H.

1980-05-01

The double acting reciprocating bellows liquid helium pump built and tested at the Lawrence Berkeley Laboratory is described. The pump is capable of delivering 50 gs -1 of liquid helium to supply the two-phase cooling sytem for a large superconducting magnet. The pump is driven by a torque motor at room temperature; the reciprocating motion is transmitted to the pump through a shaft which operates between room temperature and 4 0 K. The design details of this liquid helium pump are presented. The helium pump has operated in a helium bath and in pumped forced flow helium circuits. The results of these experimental tests are presented in this report

Helium leak testing the Westinghouse LCP coil

International Nuclear Information System (INIS)

Merritt, P.A.; Attaar, M.H.; Hordubay, T.D.

1983-01-01

The tests, equipment, and techniques used to check the Westinghouse LCP coil for coolant flow path integrity and helium leakage are unique in terms of test sensitivity and application. This paper will discuss the various types of helium leak testing done on the LCP coil as it enters different stages of manufacture. The emphasis will be on the degree of test sensitivity achieved under shop conditions, and what equipment, techniques and tooling are required to achieve this sensitivity (5.9 x 10 -8 scc/sec). Other topics that will be discussed are helium flow and pressure drop testing which is used to detect any restrictions in the flow paths, and the LCP final acceptance test which is the final leak test performed on the coil prior to its being sent for testing. The overall allowable leak rate for this coil is 5 x 10 -6 scc/sec. A general evaluation of helium leak testing experience are included

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.

Buffer-gas cooling of antiprotonic helium to 1.5 to 1.7 K, and antiproton-to–electron mass ratio

CERN Document Server

Hori, Masaki; Sótér, Anna; Barna, Daniel; Dax, Andreas; Hayano, Ryugo; Kobayashi, Takumi; Murakami, Yohei; Todoroki, Koichi; Yamada, Hiroyuki; Horváth, Dezső; Venturelli, Luca

2016-01-01

Charge, parity, and time reversal (CPT) symmetry implies that a particle and its antiparticle have the same mass. The antiproton-to-electron mass ratio Embedded Image can be precisely determined from the single-photon transition frequencies of antiprotonic helium. We measured 13 such frequencies with laser spectroscopy to a fractional precision of 2.5 × 10−9 to 16 × 10−9. About 2 × 109 antiprotonic helium atoms were cooled to temperatures between 1.5 and 1.7 kelvin by using buffer-gas cooling in cryogenic low-pressure helium gas; the narrow thermal distribution led to the observation of sharp spectral lines of small thermal Doppler width. The deviation between the experimental frequencies and the results of three-body quantum electrodynamics calculations was reduced by a factor of 1.4 to 10 compared with previous single-photon experiments. From this, Embedded Image was determined as 1836.1526734(15), which agrees with a recent proton-to-electron experimental value within 8 × 10−10.

Improved Study of the Antiprotonic Helium Hyperfine Structure

CERN Document Server

Pask, T.; Dax, A.; Hayano, R.S.; Hori, M.; Horvath, D.; Juhasz, B.; Malbrunot, C.; Marton, J.; Ono, N.; Suzuki, K.; Zmeskal, J.; Widmann, E.

2008-01-01

We report the initial results from a systematic study of the hyperfine (HF) structure of antiprotonic helium (n,l) = (37,~35) carried out at the Antiproton Decelerator (AD) at CERN. We performed a laser-microwave-laser resonance spectroscopy using a continuous wave (cw) pulse-amplified laser system and microwave cavity to measure the HF transition frequencies. Improvements in the spectral linewidth and stability of our laser system have increased the precision of these measurements by a factor of five and reduced the line width by a factor of three compared to our previous results. A comparison of the experimentally measured transition frequencies with three body QED calculations can be used to determine the antiproton spin magnetic moment, leading towards a test of CPT invariance.

Formation of the lunar helium corona and atmosphere

Science.gov (United States)