Results 11 to 20 of about 559,916 (326)

Helium Emissions Observed in Ground-Based Spectra of Solar Prominences [PDF]

, 2012
The only prominent line of singly ionized helium in the visible spectral range, helium-II 4686 A, is observed together with the helium-I 5015 A singlet and the helium-I 4471 A triplet line in solar prominences.
Bianda, Michele, Ramelli, Renzo, Stellmacher, Goetz, Wiehr, Eberhard   +3 more
core   +2 more sources

Neonatal Applications of Heliox: A Practical Review

Frontiers in Pediatrics, 2022
Heliox is a mixture of helium and oxygen that may be utilized as an alternative to air-oxygen during the ventilatory support in the neonate. Special physical properties of Heliox, particularly low density, allow for improved gas flow and diffusion. First
Tomasz Szczapa, Patryk Kwapień, T. Allen Merritt   +2 more
doaj   +1 more source

Cavitation pressure in liquid helium [PDF]

, 2001
Recent experiments have suggested that, at low enough temperature, the homogeneous nucleation of bubbles occurs in liquid helium near the calculated spinodal limit. This was done in pure superfluid helium 4 and in pure normal liquid helium 3. However, in
B. M. Abraham, B. M. Abraham, C. E. Campbell, D. M. Jezek, F. Caupin, F. Caupin, F. Caupin, F. Dalfovo, G. H. Bauer, G. W. Waters, H. J. Maris, H. J. Maris, H. Lambaré, J. A. Nissen, J. Boronat, J. C. Wheatley, J. Casulleras, J. Wilks, K. Dransfeld, Lord Rayleigh, M. A. Solis, M. Guilleumas, M. Guilleumas, M. Kollar, M. P. Bertinat, P. Roche, S. Balibar, S. Balibar, S. Balibar, S. N. Burmistrov, W. H. Press, X. Chavanne   +31 more
core   +3 more sources

Rb*He_n exciplexes in solid 4_He [PDF]

, 2006
We report the observation of emission spectra from Rb*He_n exciplexes in solid 4He. Two different excitation channels were experimentally identified, viz., exciplex formation via laser excitation to the atomic 5P3/2 and to the 5P1/2 levels.
Hofer, A., Moroshkin, P., Nettels, D., Ulzega, S., Weis, A.   +4 more
core   +2 more sources

Effect of helium as process gas on laser powder bed fusion of Ti-6Al-4V studied with operando diffraction and radiography

European Journal of Materials, 2022
The utilisation of helium as process gas in laser powder bed fusion limits the generation of Ti-6Al-4V hot and incandescent spatters and enhances their cooling rate.
Camille Pauzon, Steven Van Petegem, Eduard Hryha, Cynthia Sin Ting Chang, Samy Hocine, Helena Van Swygenhoven, Charlotte de Formanoir, Sophie Dubiez-Le Goff   +7 more
doaj   +1 more source

The helium trimer with soft-core potentials [PDF]

, 2011
The helium trimer is studied using two- and three-body soft-core potentials. Realistic helium-helium potentials present an extremely strong short-range repulsion and support a single, very shallow, bound state.
A. Kievsky, A. Kievsky, A.K. Motovilov, A.R. Holt, A.R. Janzen, B.D. Esry, C. Romero-Redondo, C. Romero-Redondo, E. Garrido, E. Nielsen, E. Nielsen, E.A. Kolganova, E.A. Kolganova, F. Luo, F.E. Harris, H. Suno, J. Stecher von, K.T. Tang, M. Jeziorska, M. Lewerenz, M.V. Zhukov, P. Barletta, P. Barletta, P. Barletta, P. Barletta, R. Grisenti, R.A. Aziz, R.A. Aziz, T. Korona, V. Efimov, V. Efimov, V. Roudnev, W. Cencek, W. Schoellkopf, W. Schollkopf   +34 more
core   +3 more sources

Electric-field-induced helium-helium resonances

Physical Review A, 2019
The tunability of the helium-helium interaction through an external electric field is investigated. For a static external field, electric-field induced resonances and associated electric-field induced bound states are calculated for the $^4$He-$^4$He, $^3$He-$^4$He, and $^3$He-$^3$He systems. Qualitative agreement is found with the literature for the $^
Guan, Qingze, Blume, Doerte
openaire   +3 more sources

Free-energy model for fluid helium at high density [PDF]

, 2004
We present a semi-analytical free-energy model aimed at characterizing the thermodynamic properties of dense fluid helium, from the low-density atomic phase to the high-density fully ionized regime. The model is based on a free-energy minimization method
Christophe Winisdoerffer, G. Chabrier, Gilles Chabrier, L. Landau   +3 more
core   +2 more sources

Monitoring Scheme for the Detection of Hydrogen Leakage from a Deep Underground Storage. Part 1: On-Site Validation of an Experimental Protocol via the Combined Injection of Helium and Tracers into an Aquifer

Applied Sciences, 2020
Massive underground storage of hydrogen could be a way that excess energy is produced in the future, provided that the risks of leakage of this highly flammable gas are managed. The ROSTOCK-H research project plans to simulate a sudden hydrogen leak into
Stéphane Lafortune, Philippe Gombert, Zbigniew Pokryszka, Elodie Lacroix, Philippe de Donato, Nevila Jozja   +5 more
doaj   +1 more source

A comparative study of single-particle cryo-EM with liquid-nitrogen and liquid-helium cooling

IUCrJ, 2019
Radiation damage is the most fundamental limitation for achieving high resolution in electron cryo-microscopy (cryo-EM) of biological samples. The effects of radiation damage are reduced by liquid-helium cooling, although the use of liquid helium is more
Olivia Pfeil-Gardiner, Deryck J. Mills, Janet Vonck, Werner Kuehlbrandt   +3 more
doaj   +1 more source