نتایج جستجو برای: helium purification
تعداد نتایج: 71071 فیلتر نتایج به سال:
Electrons on helium substrates form a model Coulomb system in which the transition from classical electron liquid to Wigner crystal is readily observed. However, attempts to increase the electron density in order to observe the ‘quantum melting’ of the system to a Fermi degenerate gas are hindered by an instability of the helium surface. Here we describe experimental efforts to reach the degene...
The deep interiors of Jupiter and Saturn consist of fluid, metallic hydrogen. In Jupiter the metallic hydrogen is uniformly mixed with helium. In Saturn, the incomplete solubility of helium may cause unmixing and energy release. In the interiors of Uranus and Neptune the fluid mixture (of hydrogen, helium, water, methane and ammonia) is metallic or ionic. The terrestral planetary cores are pred...
Warm Neptuneand sub-Neptune-sized exoplanets in orbits smaller than Mercury’s are thought to have experienced extensive atmospheric evolution. Here we propose that a potential outcome of this atmospheric evolution is the formation of helium-dominated atmospheres. The hydrodynamic escape rates of Neptuneand subNeptune-sized exoplanets are comparable to the diffusion-limited escape rate of hydrog...
We present a semianalytical 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 and includes various different contributions representative of the correlations between atomic and ionic species and electrons. This model allo...
In this paper we present a non-parametric approach to solving the helium speech problem. Properties of helium speech are replaced by those pertaining to normal speech by means of codebook mapping of spectral envelopes. This method eliminates the drawbacks inherent in the previous procedures of helium speech unscrambling as it requires neither model of helium speech production nor estimation of ...
The cryogenic system for the KSTAR superconducting magnets has been commissioned. It consists of a cold box, distribution boxes (DB) and cryogenic transfer lines. The cold box and DB #1 provide 600 g/s of supercritical helium to cool the superconducting (SC) magnets, their SC bus-lines, and the magnet support structures. It also provides 17.5 g/s of liquid helium to the current leads and suppli...
Headspace oxygen in sample vial for the purge-and-trap dynamic headspace/gas chromatography method oxidizes meat if held hours before purging, influences volatile profiles, and misrepresents the true composition of volatiles. Helium flush and helium flush plus oxygen absorber were used to eliminate residual oxygen and minimize oxidative changes in meat during sample holding time. Both helium fl...
Birthdays are always a time for introspection and, given the number of fingers humans generally have, a one hundredth birthday is especially so. Almost exactly a century ago, in April 1911, the laboratory run by Heike Kamerlingh Onnes at the University of Leiden discovered a sudden transition to zero resistance in high-purity mercury on cooling through 4.2 K. At the time, Onnes was basking in t...
We study two techniques to create electrons in a liquid helium environment. One is thermionic emission of tungsten filaments in a low temperature cell in the vapor phase with a superfluid helium film covering all surfaces; the other is operating a glowing filament immersed in bulk liquid helium. We present both the steady state and rapid sweep I-V curves and the electron current yield. These cu...
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