Measurement of electronegativity during the E to H mode transition in a radio frequency inductively coupled Ar/O2 plasma

This paper presents the evolution of the electronegativity with the applied power during the E to H mode transition in a radio frequency(rf)inductively coupled plasma(ICP)in a mixture of Ar and O2.The densities of the negative ion and the electron,as well as their ratio,i.e.,the electronegativity,are measured as a function of the applied power by laser photo-detachment combined with a microwave resonance probe,under different pressures and O2 contents.Meanwhile,the optical emission intensities at Ar 750.4 nm and O 844.6 nm are monitored via a spectrograph.It was found that by increasing the applied power,the electron density and the optical emission intensity show a similar trench,i.e.,they increase abruptly at a threshold power,suggesting that the E to H mode transition occurs.With the increase of the pressure,the negative ion density presents opposite trends in the E-mode and the H-mode,which is related to the difference of the electron density and energy for the two modes.The emission intensities of Ar 750.4 nm and O 844.6 nm monotonously decrease with increasing the pressure or the O2 content,indicating that the density of high-energy electrons,which can excite atoms,is monotonically decreased.This leads to an increase of the negative ion density in the H-mode with increasing the pressure.Besides,as the applied power is increased,the electronegativity shows an abrupt drop during the E-to H-mode transition.

On the Absurdity of " Mobile Phone Triggered Lightning "

That making phone calls had nothing to do with lightning strike was proved from the aspects of radio wave characteristics,receiving and transmitting frequency,power as well as the electromagnetic induction of mobile phones. And through assuming mobile phone could trigger lightning,the probable death toll disproved the absurdity of mobile phone triggered lightning. And we concluded that making phone calls in thundery days would not increase the probability of lightning stroke,and calls could be made in thundery days as long as in the safe position.

Synthesis of Single-Walled Carbon Nanotubes by Induction Thermal Plasma

The production of high quality single-walled carbon nanotubes(SWCNTs)on a bulk scale has been an issue of considerable interest.Recently,it has been demonstrated that high quality SWCNTs can be continuously synthesized on large scale by using induction thermal plasma technology.In this process,the high energy density of the thermal plasma is employed to generate dense vapor-phase precursors for the synthesis of SWCNTs.With the current reactor system,a carbon soot product which contains approximately 40 wt%of SWCNTs can be continuously synthesized at the high production rate of~100 g/h.In this article,our recent research efforts to achieve major advances in this technology are presented.Firstly,the processing parameters involved are examined systematically in order to evaluate their individual inuences on the SWCNT synthesis.Based on these results,the appropriate operating conditions of the induction thermal plasma process for an effective synthesis of SWCNTs are discussed.A characterization study has also been performed on the SWCNTs produced under the optimum processing conditions.Finally,a mathematical model of the process currently under development is described.The model will help us to better understand the synthesis of SWCNTs in the induction plasma process.