Neon Research Articles

Collaborating with NEON

Collaborating with NEON

3D effects of neon injection positions on the toroidally symmetric/asymmetric heat flux distribution on EAST

The heat flux deposition on the divertor targets with neon impurity injection on EAST has been investigated using the three-dimensional (3D) edge transport code EMC3-EIRENE. The impact of different poloidal neon injection positions on heat flux deposition has been studied. It was found that neon impurities injected at the in- and out-board divertors (i.e. strike points) lead to toroidally asymmetric distributions of heat load on the in- and out-board targets, respectively. However, neon gas puffing upstream shows a toroidally symmetric distribution of heat load. The 3D effects of the neon radiation on the heat load have been investigated with the help of a field line tracing technique, which indicates that neon impurities injected near the strike point can radiate more power and result in a lower heat load compared with upstream neon injection. In order to further verify the asymmetric distribution of heat load, two impurity injection locations away from the strike points at the divertor are investigated, which show the symmetric distribution of heat load as with the upstream neon injection.

Experimental investigation of spin noise spectroscopy of rubidium atomic ensemble

Spin noise spectroscopy is a very sensitive undisturbed spectroscopic technique for measuring atomic spin fluctuations by using a far-detuned probe laser beam. In this paper, we describe an experimental setup for measuring the spin noise spectroscopy. The spin noise spectra of Rubidium atomic vapor cell filled with 10 Torr of Neon gas and 20 Torr of Helium gas as buffer gas are investigated in a magnetically shielded environment. The dependence of the spin noise power spectral density, separately, on the probe beam’s intensity (<i>I </i>), the probe beam’s frequency detuning (<i>Δ</i>) and Rubidium atomic number density (<i>n</i>) are measured. The integrated power of Rubidium atomic spin noise spectra is scaled as<inline-formula><tex-math id="M1">\begin{document}$ {I^2}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="23-20201103_M1.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="23-20201103_M1.png"/></alternatives></inline-formula>. Owing to homogeneous broadening, the full width at half maximum of transmission spectrum of the same cell is broadened to <inline-formula><tex-math id="M2">\begin{document}$\Delta {\nu _t} = {\rm{6}}.{\rm{9}}\;{\rm{GH}}{\rm{z}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="23-20201103_M2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="23-20201103_M2.png"/></alternatives></inline-formula>. Center frequency of transmission spectrum is set to be <inline-formula><tex-math id="M3">\begin{document}$\varDelta = {\rm{0}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="23-20201103_M3.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="23-20201103_M3.png"/></alternatives></inline-formula>. The probe beam’s frequency detuning is larger than the half width at half maximum of the transmission spectrum <inline-formula><tex-math id="M4">\begin{document}$\left| \varDelta \right| > {{\Delta {\nu _t}}}/{{\rm{2}}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="23-20201103_M4.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="23-20201103_M4.png"/></alternatives></inline-formula>, so the integrated power of Rubidium atomic spin noise spectra is scaled as <inline-formula><tex-math id="M5">\begin{document}$\varDelta^{-1}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="23-20201103_M5.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="23-20201103_M5.png"/></alternatives></inline-formula>. And there is a dip for <inline-formula><tex-math id="M6">\begin{document}$|\varDelta| < {{\Delta {\nu _t}}}/{{\rm{2}}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="23-20201103_M6.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="23-20201103_M6.png"/></alternatives></inline-formula> as a result of collisions between the buffer gas and Rubidium atoms. The integrated power of Rubidium atomic spin noise spectra is scaled as <inline-formula><tex-math id="M7">\begin{document}$ \sqrt n $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="23-20201103_M7.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="23-20201103_M7.png"/></alternatives></inline-formula>. The Rubidium atomic spin's transverse relaxation time becomes shorter while the temperature increases. Only at the condition of non-perturbative probe, including far-off-resonant laser, weak laser intensity and uniform transverse magnetic field, the measured full width at half maximum will be close to the intrinsic linewidth of spin noise spectrum. In this way, we can obtain the Rubidium atomic spin's transverse relaxation time. This work can be applied to the field of physical constants precision measurement, like Lande <i>g</i> factor and isotopic abundance ratio. In addition, it provides an important reference for developing the high signal-to-noise ratio and compact spin noise spectrometer.

Observation of deuterium molecule emission spectra under an active feedback control of H-mod plasma divertor detachment experiment on the EAST tokamak**Project supported by the National Natural Science Foundation of China (Grant No. 11805234).

Based on neon gas puffing, an active feedback control of H-mod plasma divertor detachment experiment was successfully operated on the EAST tokamak. During the feedback control discharge, the plasma was detached by puffing neon gas and the strike point splitting phenomenon on divertor target was also clearly observed by divertor probes diagnostic. In boundary region, many neutral particle processes (atom and molecule) were happened and accompanied by their emission spectra under the detachment discharge. By studying these emission spectra, it is helpful for us to understand the role of atoms and molecules in boundary recycling, which is important for studying the physical mechanism of divertor detachment. For the Fulcher-α system (, D2 emission spectra in the range from 601 nm to 606 nm were observed, identified and fitted in the detachment experiment for the first time on the EAST, and the spectra in the Q(0–0) band ( in the Q branch of the Fulcher-α system were used for detailed analysis to acquire the boundary region temperature Te (below 5 eV), which could not be provided very well by other diagnostics on the EAST. An electronic version deuterium molecular spectral line database was established to identify the spectral lines and a multi-peak fitting program was developed to fit and analyze the observed spectra.

Spectral splitting and phase matching of the macroscopic high-order harmonic generation in intense laser fields

We theoretically investigate the macroscopic high-order harmonic generation in argon gaseous medium by numerically solving the three-dimensional macroscopic propagation equation, and the results show that the harmonic spectral and spatial profiles of harmonics are gradually splitting with the increasing of the driving laser intensity. This splitting is mainly due to the distortions which the driving field suffers during propagation and the consequence is also on phase matching. To illustrate the physical mechanisms of harmonic splitting, a theoretical analysis of the phase matching is presented. The harmonic spectra from different focus positions reveal that the split is dependent on the focus-gas-jet relative position. Moreover, we demonstrate that the spectral splitting of high harmonics can hardly be observed for neon gas jet due to the high ionization energy.

Formation of an oxide layer on a biomaterial Co-Cr-Mo alloy by using a hollow-cathode glow discharge plasma with argon-oxygen and neon-oxygen mixed gases

A plasma treatment was investigated as a way to form an oxide layer on a biomaterial Co-Cr-Mo alloy (CCM alloy); the method uses a hollow-cathode-type glow discharge as the atomization/reaction source, and it is under in situ monitoring of the emission signal from the plasma. This study focused on how the plasma condition could be optimized to form a stable passivation layer on the CCM alloy based on the spectrometric information. For this purpose, a hollow-cathode-type glow discharge source was employed to form an oxide layer with a pure chromium target to be sputtered in argon-oxygen and neon-oxygen mixed gas plasmas. The thickness of the layer gradually became elevated with increasing oxygen gas partial pressure, and the layer grew more rapidly when neon mixed gas was used in place of argon. A notable feature of this method is that a surface layer of Cr2O3 can be produced with a thickness of up to several hundred nanometers after a treatment time of only a few minutes, which could occur when neon mixed gas plasma was operated under the optimized discharge condition.

Generation of K-Shell Radiation of Noble Gases in the Microsecond Implosion Regime

Studies of K-shell plasma radiation sources were performed on the GIT-12 generator (4.7 MA, 1.7 μs). In the experiments, a new type of load configuration was used to form the Z-pinch plasma – a gas puff with an outer plasma shell. Noble gases neon and argon were used as working gases. The gas puff consisted of two cascades: a hollow cylindrical shell outside and a solid jet inside. The outer plasma shell was created with the help of plasma guns located on a diameter of 350 mm. A distinctive feature of these studies is that the experiments with the plasma radiation source were carried out in the microsecond implosion regime usually leading to a significant decrease in the efficiency of generation of K-shell x-rays. The use of the Z-pinch load of a new type significantly improved the efficiency of the microsecond plasma radiation source. As a result of optimization of the initial gas-puff parameters, a neon K-shell radiation yield of 14.7 kJ/cm at a peak implosion current of 3.5 MA was achieved. In experiments with argon gas puffs, the radiation yield reached 1.9 kJ/cm at a peak implosion current of 3.1 MA.

Reimagining NEON Operations: We Can Do Better

Reimagining NEON Operations: We Can Do Better

Upper Ocean Distribution of Glacial Meltwater in the Amundsen Sea, Antarctica

AbstractPine Island Ice Shelf, in the Amundsen Sea, is losing mass due to increased heat transport by warm ocean water penetrating beneath the ice shelf and causing basal melt. Tracing this warm deep water and the resulting glacial meltwater can identify changes in melt rate and the regions most affected by the increased input of this freshwater. Here, optimum multiparameter analysis is used to deduce glacial meltwater fractions from independent water mass characteristics (standard hydrographic observations, noble gases, and oxygen isotopes), collected during a ship‐based campaign in the eastern Amundsen Sea in February–March 2014. Noble gases (neon, argon, krypton, and xenon) and oxygen isotopes are used to trace the glacial melt and meteoric water found in seawater, and we demonstrate how their signatures can be used to rectify the hydrographic trace of glacial meltwater, which provides a much higher‐resolution picture. The presence of glacial meltwater is shown to mask the Winter Water properties, resulting in differences between the water mass analyses of up to 4‐g/kg glacial meltwater content. This discrepancy can be accounted for by redefining the “pure” Winter Water endpoint in the hydrographic glacial meltwater calculation. The corrected glacial meltwater content values show a persistent signature between 150 and 400 m of the water column across all of the sample locations (up to 535 km from Pine Island Ice Shelf), with increased concentration toward the west along the coastline. It also shows, for the first time, the signature of glacial meltwater flowing off‐shelf in the eastern channel.

Dynamics of neon ions after neon gas seeding into tokamak plasma

Two dimensional interchange turbulence has been used to describe neon gas interaction with tokamak plasma, and is able to include anomalous transport effects self-consistently in the edge and scrape-off layer (SOL) regions. Model equations related to the plasma turbulence coupled with neon gas have been solved numerically using the BOUT++ framework code. Two different fluid models of the neon gas have been investigated, and in this context a few results related to the Aditya tokamak are presented. Numerical results indicate that ionization and radiative cooling processes modify the plasma turbulence. The existence of neon ions and their radial profile in the edge and SOL regions are the most significant results in this work. This new result has been investigated in detail in the presence of the interchange plasma turbulence. Other relevant results such as an increase of plasma density and a small change of electron temperature are also presented. In turbulence saturated states the electron temperature can increase slightly even in the presence of radiative cooling. Neon ions in the presence of polarization drift and radiative cooling modify the radial electric field and its radial shear. Radial electron energy flux has been investigated in the context of poloidal velocity shear and turbulence decorrelation rates. An increase of the electron energy confinement time has been observed numerically, mainly in the SOL region in the presence of gas seeding. Experimental results show an increase of global energy confinement time only when the gas seeding becomes effective in changing the global plasma parameters.

Observations of toroidal plasma rotation reversal in the Aditya-U tokamak

An impurity ion toroidal rotation profile has been observed in the ohmic discharges of the Aditya-U tokamak from the Doppler-shifted passive charge exchange line emission of C5+ at 529 nm. The line has been monitored using a space-resolved visible spectroscopy diagnostic consisting of a 1 m multi-track spectrometer coupled with a charge coupled device (CCD) detector. In typical discharges with central chord-averaged electron density ≲2.5 × 1019 m−3, the maximum toroidal rotation velocity at the plasma core is found to be −20 km s−1 in the counter-current direction. Reversal of plasma toroidal rotation is observed for high electron density discharges with a central chord-averaged density of ~5 × 1019 m−3. During the rotation reversal, the direction of toroidal rotation changes to the co-current direction in the core. Interestingly, in the discharges with a central chord-averaged electron density of ≲2.5 × 1019 m−3, where neon gas is injected at the plasma current flat-top, the toroidal rotation reversal has been observed after the gas puff.

Welding Technique Training and Neon Box Advertising Board for Youth Work Groups in Areas Affected by Earthquake Disasters

Abstract: Cubadak Air and Sikapak Barat villages are two villages from many villages affected by the earthquake that hit West Sumatra in 2009. The impact is still felt today. More than eighty percent of the houses and economic facilities of the people in this area were destroyed, so there was a lot of unemployment in this village. The purpose of this activity was to train groups of out of school youth in Cubadak Air and Sikapak Barat villages about welding techniques and the manufacture of neon box advertising boards. The method used in this activity is the provision of theories about the science of materials, welding, workshop management, welding practice techniques, and the manufacture of billboards. The results of this activity were the completion of the signboard of the Al-Abrar Great Mosque and the "Piaman Saiyo" Community Training Center in Cubadak Air Village.Key words: Workmanship, Billboards, Neon boxes, Skills Abstrak. Desa Cubadak Air dan Sikapak Barat adalah dua desa dari banyak desa yang terkena bencana gempa yang melanda Sumatera Barat pada tahun 2009 lalu. Dampaknya hingga kini masih terasa. Lebih delapan puluh persen rumah dan fasilitas perekonomian masyarakat di daerah ini hancur, sehingga di desa ini banyak terjadi pengangguran. Tujuan dari kegiatan ini untuk melatih kelompok pemuda putus sekolah di Desa Cubadak Air dan Sikapak Barat tentang teknik pengelasan dan pembuatan papan iklan dari neon box. Metode yang dilakukan dalam kegiatan ini adalah pemberian teori tentang ilmu bahan, las, manjemen bengkel, teknik praktek las, dan pembuatan papan iklan. Hasil yang dicapai dari kegiatan ini adalah telah selesainya papan nama Masjid Raya Al-Abrar dan Pusat Pelatihan Masyarakat “Piaman Saiyo” di Desa Cubadak Air.Keywords: Tuna karya, Papan iklan, Neon box, Skill

Development of spherical proportional counter for light WIMP search within NEWS-G collaboration

The Spherical gaseous detector (or Spherical Proportional Counter, SPC) has a broad range of applications. In this work, we will focus on the light WIMP Dark Matter particle search, that is, below a few GeV. The NEWS-G collaboration operates a 60 cm diameter detector at Modane underground laboratory (LSM). Running the detector at 3 bars of Neon gas, some competitive limits have been set down to 0.5 GeV WIMP mass thanks to an energy threshold of around 100 eV. To reach better performances, the next generation of SPC (140 cm), NEWS-G_SNO, is under construction. We will focus here on the fabrication method, the different low energy calibration methods using 37Ar, neutron and UV laser, on the cleaning methods to remove the surface contamination and mitigation of 210Pb bulk contamination.

Impact of impurity mixture gas seeded by supersonic molecular beam injection on edge-localized modes in the HL-2A tokamak

Impurity seeding experiments in ELMy H-mode plasmas by using supersonic molecular beam injection (SMBI) have been performed in the HL-2A tokamak. Besides pure impurity gas (neon, argon), impurities mixed with the main ion fuelling gas by different ratios were seeded into the plasma. It has been observed that the ELM behavior and plasma confinement are very sensitive to the impurity ratio. For 30% Ne impurity seeding, large ELMs are replaced by high frequency bursts (HFBs), which have higher frequency and smaller amplitude compared to the ELMs and the peak heat load on the divertor plate was considerably reduced. Analyses indicate that HFBs originate from the pedestal region and enhance the pedestal particle transport, resulting in a softened pedestal gradient after SMBI. However, for the pure Ne and Ar SMBI seeding, the ELM frequency is decreased and the plasma confinement is moderately improved. Experimental observations suggest that the impurity mixture gas plays a role in changing the pedestal dynamics and there should be an optimal impurity ratio for efficient heat load control in ELMy H-mode plasmas.

Effects of thermal loads representations on the dynamics and characteristics of carbon nanotubes-based mass sensors

Uniform, linear, and nonlinear temperature gradients are considered to perform buckling and vibration analyses of carbon nanotube (CNT)-based mass sensors modeled as a clamped-clamped Euler–Bernoulli nanobeam with a deposited atomic-scale particle. Size dependent effects are taken into account using the Eringen’s nonlocal elasticity theory. Employing the Hamilton’s principle, the governing equations of motion considering the three types of temperature distribution are derived. To investigate the effects of various thermal loadings on the mass detection sensitivity of clamped CNT-mass detectors, four distinct noble gas atoms, namely Helium (He), Neon (Ne), Argon (Ar), and Krypton (Kr) with very low chemical reactivity are considered as attached atomic-scale masses. The influence of important parameters, such as the length and diameter of the CNT, the deposited mass and its location, the nonlocal parameter, the surface temperature difference, the temperature rise, and the type of temperature distribution on the errors in thermal buckling loads and frequency shifts are also studied. Assessing the impacts of the inaccuracies of uniform and linear temperature distributions on the critical thermal buckling load and the frequency shift of the CNT-based mechanical resonator is the primary contribution of the work. The numerical results indicate that in the pre-buckling region, the assumptions of uniform and linear temperature distributions through the thickness of the CNT estimate higher values of the natural frequency and the frequency shift compared to the nonlinear temperature gradient. On the contrary, the nonlinear thermal gradient across the radius of the CNT-based mass detector yields the largest values of the frequency shift and hence the highest mass detection sensitivities of the CNT-based mass sensor in the post-buckling configuration.

Overview of operation and experiments in the ADITYA-U tokamak

The first Indian tokamak, ADITYA, operated for over two decades with a circular poloidal limiter, has been upgraded to a tokamak named ADITYA Upgrade (ADITYA-U) to attain shaped-plasma operations with an open divertor in single and double-null configurations. Experimental research using ADITYA-U has made significant progress since the last FEC in 2016. After installation of a plasma facing component and standard tokamak diagnostics in ADITYA-U, the Phase-I plasma operations were initiated in December 2016 with a graphite toroidal belt limiter. Ohmically heated circular plasmas supported by filament pre-ionization with plasma parameters Ip ~ 80–95 kA, duration ~80–180 ms, with a maximum toroidal field ~1 T and chord averaged electron density ~2.5 × 1019 m−3, have been obtained. The runaway electron (RE) generation, transport and mitigation experiments, along with magneto hydrodynamic (MHD) activities and density enhancement with H2 gas puffing experiments were carried out in Phase-I, which was completed in March 2017. Preparation for the Phase-II operation in ADITYA-U includes calibration of magnetic diagnostics followed by commissioning of major diagnostics and installation of a baking system. After repeated cycles of baking the vacuum vessel up to ~135 °C, the Phase-II operations resumed in February 2018 and are continuing to achieve plasma parameters close to the design parameters of circular limiter plasmas, using real-time plasma position control. The plasma current has been raised to ~135 kA in Phase-II, with a maximum chord averaged electron density of ~4 × 1019 m−3. Hydrogen gas breakdown has been observed in more than 2000 discharges, including Phase-I and Phase-II operations, without a single failure. Several experiments have been carried out, including the control of REs with the fuelling of supersonic molecular beam injection as well as sonic H2 gas puffing during current flat-top, MHD mode studies using multiple periodic gas puffs, and radiative improved modes using neon gas puffs. The experimental results from Phase-I and Phase-II operations of the ADITYA-U tokamak are discussed in this paper.

Development of 10 kW turbo-Brayton refrigerator for HTS power applications

HTS power applications have been developed actively and the refrigerator requires larger cooling power. To satisfy this request we have developed 10 kW class turbo-Brayton refrigerator which has neon gas as working fluid. The refrigerator consists of a pair of turbine-compressors which have turbine, compressor and PM motor on the same shaft. The turbine-compressor has magnetic bearings with no rubbing parts, which results in a long maintenance interval. Neon gas is compressed from 0.5 MPa at inlet to 1.0 MPa at outlet by two compressors and expands through two turbines in parallel. Design cooling capacity is 10 kW at a cooling temperature of 65 K. We made a commercial model refrigerator and tested cool down characteristics, load cycles and cooling capacity using a liquid nitrogen circulation system. Specification and configuration of the refrigerator and test results are shown in this paper.

Low pressure fusion exhaust gases separation

Plasma enhancement gases (PEGs) (such as: nitrogen, neon, argon and other inert gases) are injected into the plasma of several tokamaks in order to reduce the power load over the plasma facing components. The exhaust gas in the tokamak demonstration reactor (DEMO) consists of more than 90% of unburned fuel gas (D and T) and the remaining part will be He, PEGs and impurities. In DEMO reactor it is foreseen to recover the fuel gas and PEGs. The research focuses to remove the He from fuel gas and PEGs from fusion reactor. For this purpose, six commercial ceramic membranes have been tested at a permeation apparatus built at ENEA Casaccia laboratories. Single gas permeances for H2, He, Ar and air were measured with a pressure drop across the membranes between 10 Pa up to 100 kPa at room temperature. The selectivities found are low except for the 0.5 nm pore size membranes. The membranes have been supplied by Ceramiques Tecniques et Industrielles (CTI SA, France).

A thermodynamic model for mobility in neon gas over broad density and temperature ranges

We report new measurements of the mobility μ of ions in supercritical neon gas in the range for number density nm−3. We rationalize the experimental data of all isotherms using the Stokes–Cunningham formula by computing the ion hydrodynamic radius as a function of T and N with the thermodynamic free volume model developed for the ion mobility in superfluid helium. The model parameters are determined by re-analyzing published data for T = 45 K for N up to N ≈ 1.65Nc (Nc ≈ 14.4 nm−3 is the critical number density), which roughly span four orders of magnitude of the Knudsen number , covering the transition from the kinetic to the hydrodynamic transport regime. These parameters provide an excellent description of the dependence of μ on N for all higher isotherms and yield a strict test of the model validity, thereby bridging the gap between the kinetic and the hydrodynamic transport regimes.

Design and performance of bending-magnet beamline BL02B at the SSRF.

The BL02B bending-magnet beamline at the Shanghai Synchrotron Radiation Facility (SSRF) has been constructed and is now operational for ambient-pressure photoelectron spectroscopy (APPES) and photon-in/photon-out spectroscopy (PIPOS) experimental use. Optical optimization was implemented for realization of high performance, e.g. photon flux, energy-resolving power and focus spot size. X-ray photoelectron spectroscopy experiments show that the energy range extends from 40 to 2000 eV. Argon, nitrogen and neon gas core-shell excitation spectra indicate energy-resolving powers of over 1.4 × 104 @ 244 eV, 1.0 × 104 @ 401 eV and 7.0 × 103 @ 867 eV, respectively. The measured photon flux is 1.3 × 1011 photons s-1 @ E/ΔE = 3700 at 244 eV at the expected sample position, for the SSRF electron energy of 3.5 GeV and electron current of 240 mA. The spot sizes are 177 µm × 23 µm and 150 µm × 46 µm at the APPES and PIPOS samples, respectively.