Studies on the motion and radiation of interior plasmas in gas-filled hohlraums with different laser entrance hole sizes

An experiment on 100 k J laser facility is performed to study the motive features and radiation properties of plasmas from different areas inside gas-filled cylindrical hohlraums.These hohlraums are designed to possess one open end and one laser entrance hole(LEH)with different diameters,which would or not result in the blocking of the LEH.An x-ray streak camera that is set at 16 degrees with respect to the hohlraum axis is applied to acquire the timeresolved x-ray images from the open end.Based on the images,we can study the evolutions of the wall plasma,corona bubble plasma and LEH plasma simultaneously through an equivalent view field of hohlraum interior.Multi-group flat response x-ray detectors are applied to measure the x-ray fluxes.In order to understand these characteristics,our two-dimensional radiation hydrodynamic code is used to simulate the experimental results.For the accuracy of reproduction,dielectronic recombination and two parameter corrections are applied in our code.Based on the comparison between experiments and simulations,we quantitatively understand the blocking process of LEH and the motion effects of other plasmas.The calibrated code is beneficial to design the gas-filled hohlraum in a nearby parameter space,especially the limit size of LEH.

Third-Harmonic Generated in EH32 Mode of a Gas-Filled WavegUide by fs Laser Pulses

In this paper it is reported for the first time that the third harmonic generated in EH32 mode of a gas-filled waveguide by fs pulses has higher generation efficiency. The new finding contrasts with the experiment in It. G. Durfee Ⅲ, S. Backus, M.M. Murnane, and H.C. Kapteyn, Opt. Left. 22 （1997） 1565]. Some possible factors, which produce the contradiction, are discussed briefly.

Signal-Pressure Curves of Cascaded Four-Wave Mixing in Gas-Filled Capillary by fs Pulses

The theoretical framework for the cascaded four waves mixing (CFWM) in gas-filled capillary by fs pulses is constructed. Based on the theoretical framework, the signal-pressure curves (SPC) of the CFWM in gas-filled capillary by fs pulses are calculated. With a comparison between the theoretical and experimental SPC we have discussed the influence of the walk-off and Phase modulation on the SPC. At the same time, we have discussed the possible origin of the first three peaks of the SPC.

Towards all-fiber structure pulsed mid-infrared laser by gas-filled hollow-core fibers

We report here on a diode-pumped pulsed mid-infrared laser source based on gas-filled hollow-core fibers(HCFs)towards an all-fiber structure by the tapering method. The pump laser is coupled into an acetylene-filled HCF through a tapered single-mode fiber. By precisely tuning the wavelength of the diode to match different absorption lines of acetylene near 1.5 μm, mid-infrared emission around 3.1–3.2 μm is generated. With 2 m HCFs and3 mbar acetylene gas, a maximum average power of 130 m W is obtained with a laser slope efficiency of ~24%.This work provides a potential scheme for all-fiber mid-infrared fiber gas lasers.

Six intragastric balloons:Which to choose?

Endoscopically placed intragastric balloons(IGBs)have played a significant role in obesity treatment over the last 30 years,successfully bridging the gap between lifestyle modification/pharmacotherapy and bariatric surgery.Since they provide a continuous sensation of satiety that helps the ingestion of smaller portions of food,facilitating maintenance of a low-calorie diet,they have generally been considered an effective and reversible,less invasive,non-surgical procedure for weight loss.However,some studies indicate that balloons have limited sustainable effectiveness for the vast majority attempting such therapy,resulting in a return to the previous weight after balloon removal.In this review we try to summarize the pros and cons of various balloon types,to guide decision making for both the physician and the obese individual looking for effective treatment.We analyzed the six most commonly used IGBs,namely the liquid-filled balloons Orbera,Spatz3,ReShape Duo and Elipse,and the gas-filled Heliosphere and Obalon-also including comments on the adjustable Spatz3,and the swallowable Obalon and Elipse-to optimize the choice for maximum efficacy and safety.

Kinetic Model of Gaseous Alkanes Formed from Coal in a Confined System and Its Application to Gas Filling History in Kuqa Depression,Tarim Basin,Northwest China

Based on the pyrolysis products for the Jurassic low-mature coal under programmed temperature,and chemical and carbon isotopic compositions of natural gas from the Kuqa Depression, the genetic origin of natural gas was determined,and then a gas filling model was established,in combination with the geological background of the Kuqa Depression.The active energy of CH_4,C_2H_6 and C_3H_8 was gotten after the data of pyrolysis gas products under different heating rates（2℃/h and 20℃/h）were fitted by the Gas Oil Ratio（GOR）Isotope Model soft.When the frequency factor（Af）was chosen as 1×10^（14）,the active energy of CH_4,C_2H_6 and C_3H_8 was 58 kcal/mol,57 kcal/mol and 54 kcal/ mol,respectively.The distributive ranges of theδ^（13）C_1,δ^（13）C_2 andδ^（13）C_3 values for the pyrolysis gas products are-35.9‰to-30.7‰,-26.2‰to-21.3‰and-26.4‰to-22.7‰,respectively.All of the natural gases from the Kuqa Depression are dominated by hydrocarbon gases,with the high gas dryness（C_1/C_（1-4））at the middle and northern parts of the depression and the low values at both east and west sides and the southern part.The carbon isotopes of methane and its homologs as a typical coal-type gas are enriched in ^（13）C,and the distributive range of theδ^（13）C_1,δ^（13）C_2 andδ^（13）C_3 value is-32‰to -38‰,-22‰to-24‰and-20‰to-22‰,respectively,with the carbon isotopes of gaseous alkanes being less negative with the carbon number.With the ethane being enriched in ^（13）C the increasing tendency of the geological reserve of natural gas in the Kuqa Depression is observed.This observed change is consistent with the results of pyrolysate gas yield of coal as a potential gas source in the Kuqa Depression,suggesting natural gas was thermally derived from the humic organic matters and the carbon isotopes of gaseous alkanes would coarsely predict the geological reserve of gas in the Kuqa Depression.Through the simulation of kinetic processes of gas generation for the Jurassic coal in the Kuqa Depression,the gas in the Kela 2 gas field would get the threshold of gas expulsion after 27 Ma,be expelled out of source rocks as＂pulse action＂,and then filled in the gas reservoir.The peak gas-filling history took place during the past 2 Ma.

THE STUDY OF SABOT-DISCARDING MECHANISM OF GAS-PROPELLED APDS

With the advantages of simpler structure, smaller disturbance and no self-hurt while discarding sabot, the gas-propelled amor-piercing projectile with discarding sabot (APDS) owns its promissing prospect. This paper has studied the gas-filling and ejecting characteristics between the gas chamber iir saber and the environment. A dynamical model describing the sabot-discarding process I?as been established The authors have also given the starling condition and the parting criterion of the parting motion during the sabot-discarding. The mellon of fire gas-propelled APDS has been carefully calculated. Finally, the effect of the gashole area has been analyzed not only on the pressure in the gas chamber near the barrel exit, but also on the sabot-discarding time and distance away from the barrel.

Toward a compact fiber comb with 1.66×10^(-12)instability based on acetylene-filled photonic microcells

We demonstrated an optical fiber frequency comb stabilized to an acetylene-filled photonic microcell.The short-term instability of the comb at 1 s gate time was 1.66×10^(-12)for a 4.2-h measurement in a laboratory environment with air conditioning.This is the best short-term stability reported for a compact fiber comb stabilized to an acetylene-filled photonic microcell at telecom wavelengths.It is particularly significant in the development of compact fiber combs with target instability of 10^(-13).Such a device has the potential to serve as an alternative to GPS in areas lacking signal coverage,including remote locations,regions with adverse weather conditions,and military intelligence areas.

Reaction^(55)Mn+^(159)Tb:preparation for the synthesis of new elements

The complete fusion reaction of^(55)Mn+^(159)Tb was studied on the gafilled recoil separator SHANS2.Nineteen ER-α1-α2 decay chains from^(210)Th produced from the 4n evaporation channel were observed.The a-particle energy and half-life of 210Th were determined as 7922(14)keV and 14(4)ms,respectively.In addition,the decay properties of Eα=7788(14)keV and T_(1/2)=36+15-8 ms were obtained for 21Th.The measured a decay prop-erties of^(210)Th and^(211)Th were consistent with literature data.The cross sections were measured to be 0.59+035 nb and 0.19-012 nb for^(210)Th and^(211)Th,respectively.The equilibrium charge state of the recoiled nucleus^(210)Th was determined experimentally.The new data were helpful for estimating the equilibrium charge states of elements 119 and 120,which could be produced via the^(240)Pu(^(55)Mn,3n)^(292)119 and^(243)Am(^(55)Mn,3m)^(295)120 reactions,respect-ively.