Pulsed CO2 laser scattering from a hydrogen arc plasma and heterodyne detection

We report the first plasma scattering experiment using a pulsed single frequency hybrid-CO₂ laser, employing heterodyne detection to resolve the spectrum. Waves propagating parallel to the electron current in a magnetically stabilised hydrogen arc plasma are detected.     

A scheme for CO2 laser scattering to measure the ion temperature in a Tokamak plasma

A simple optical scheme is proposed for scattering of pulsed high-power CO₂ laser radiation from a plasma, and to achieve heterodyne detection to receive the very low scattered radiation intensity and resolve the narrow spectrum. Ion temperature measurement with microsecond time resolution in fusion oriented Tokamak plasmas seems feasible.     

Single longitudinal mode operation of high pressure pulsed CO2 lasers

A new method of obtaining high power single frequency output is described, where pulses are built up from the single mode radiation in the cavity of a hybrid laser having both low pressure continuous and high pressure continuous and high pressure pulsed gain sections.     

Fate of CS2 in viscose process: a chemistry perspective

Cellulose dissolution in the viscose process has been facilitated through derivatization by carbon disulphide (CS₂) at xanthation stage by converting alkali cellulose (AC) to cellulose xanthate (CX). CX formation has been always accompanied with sulphur based byproducts formation as dictated by the mechanism published in earlier study (Gondhalekar et al. (Cellulose 26 3 1595–1604, 2019)). The sulphur byproducts formed during viscose synthesis are sodium sulphide (Na₂S), sodium trithiocarbonate (Na₂CS₃: TTC) and other minor sulphur compounds. These byproducts continue to form during ripening process as dictated by time and temperature coupled with concentration of free caustic and CS₂ present in the system. These byproducts get converted into sodium sulphate (Na₂SO₄), hydrogen sulphide (H₂S), CS₂ and other sulphurous compounds during spinning. Overall, uncontrolled ripening without parametric optimization adversely impacts raw material (RM) consumption and creates sustainability challenges. Overall optimization based on viscose process fundamental insights presented in this study will effectively help in achieving operational excellence by reducing rate of undesired reactions to improve RM specific consumption and will compliment overall sustainability efforts in viscose industry.

     

Alpha-tail production with ion-cyclotron-resonance heating of 4He-beam ions in JET plasmas

Third-harmonic ion-cyclotron-resonance heating of 4He-beam ions has produced for the first time on the JET tokamak high-energy populations of 4He ions to simulate 3.5 MeV fusion-born alpha (alpha) particles. Acceleration of 4He ions to the MeV energy range is confirmed by gamma-ray emission from the nuclear reaction 9Be(alpha,ngamma) 12C and excitation of Alfvén eigenmodes. Concomitant electron heating and sawtooth stabilization are observed. The scheme could be used in next-step tokamaks to gain information on trapped alpha particles and to test alpha diagnostics in the early nonactivated phase of operation.     

Equilibrium and kinetics study of uranium(VI) from aqueous solution by Citrus limetta peels

The potential of the biowaste Citrus limetta peels (CLP) was assessed for adsorption of uranium(VI) from uranyl nitrate solution. Maximum adsorption capacity of 75.33 mg g^?1 was achieved at pH 4, showing drastic falls thereafter. This was attributed to the presence of UO₂ ²⁺, UO₂OH⁺, (UO₂)₃(OH)⁵⁺ and (UO₂)₂(OH) ₂ ²⁺ ions. The peels were characterized for elucidating the role of functional groups and morphology on the sorption capacity. The isotherm studies revealed that Langmuir, Freundlich as well as Sips models give the best fit for the experimental data observing pseudo second order kinetics. The equilibrium was achieved in 90 min. The adsorption shows complex mechanism, took place by both physical and ion-exchange mechanism.     

Control of neoclassical tearing modes by sawtooth control

The onset of a neoclassical tearing mode (NTM) depends on the existence of a large enough seed island. It is shown in the Joint European Torus that NTMs can be readily destabilized by long-period sawteeth, such as obtained by sawtooth stabilization from ion-cyclotron heating or current drive. This has important implications for burning plasma scenarios, as alpha particles strongly stabilize the sawteeth. It is also shown that, by adding heating and current drive just outside the inversion radius, sawteeth are destabilized, resulting in shorter sawtooth periods and larger beta values being obtained without NTMs.     

Use of electron beam irradiation for improving reactivity of dissolving pulp in viscose process

Journal of Radioanalytical and Nuclear Chemistry - Viscose staple fibres are produced by multi-stage chemical intensive unit operations. Low pulp reactivity is the main reason for higher...