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Abrupt Change In Neon Discharge Plasma Detected Through Optogalvanic Effects, Xianming Han, Michael Blosser, Prabhakar Misra, Haridass Chandran
Abrupt Change In Neon Discharge Plasma Detected Through Optogalvanic Effects, Xianming Han, Michael Blosser, Prabhakar Misra, Haridass Chandran
Xianming Han
When a laser is tuned between two excited energy levels of a gas in a Direct Current discharge lamp, the discharge current will experience a temporary disturbance lasting tens or hundreds of microseconds known as the optogalvanic effect. We have carried out extensive studies of optogalvanic effects in neon discharge plasmas for transitions at 621.7 nm, 630.5 nm, 638.3 nm, 650.7 nm and 659.9 nm. A nonlinear least-squares Monte Carlo technique has been used to determine the relevant amplitude coefficients, decay rates and the instrumental time constant. We discovered an abrupt change in the neon discharge plasma at a discharge …
Laser Excited Population Redistribution In The 2p^53p Multiplet In Neon, Naveed Piracha, K. Duncan-Chamberlain, R. Ali, M. Kalyar, M. Mehmood, R. Ahmed, M. Baig
Laser Excited Population Redistribution In The 2p^53p Multiplet In Neon, Naveed Piracha, K. Duncan-Chamberlain, R. Ali, M. Kalyar, M. Mehmood, R. Ahmed, M. Baig
Naveed K. Piracha
Using neon hollow cathode lamp and employing laser optogalvanic technique, we have studied population redistribution in the 2p^53p multiplet. The spectra recorded in the laser energy region of 23300cm^-^1 -23600cm^-^1 show transitions originating from both the laser excited levels as well as from an adjacent level whose population builds up as a result of collisional deactivation. Employing the optical delay technique, we have been able to extract decay rates associated with the collisional population mixing of the p levels.
Measurements Of Electron Density, Temperature And Photoionization Cross Sections Of The Excited States Of Neon In A Discharge Plasma, Shaukat Mahmood, Nek Shaikh, M. Kalyar, Naveed Piracha, M. Baig
Measurements Of Electron Density, Temperature And Photoionization Cross Sections Of The Excited States Of Neon In A Discharge Plasma, Shaukat Mahmood, Nek Shaikh, M. Kalyar, Naveed Piracha, M. Baig
Naveed K. Piracha
In the present work emission and absorption spectroscopy have been used to determine the plasma parameters of neon in a hollow cathode discharge lamp. The excitation temperature is determined using the intensity ratio method and Boltzmann’s plot method whereas the electron density is determined from the Stark broadening of the spectral lines. The behavior of the optogalvanic signal as a function of laser energy has been studied for three transitions from the 2p53s [1/2]2 metastable state following ΔJ=ΔK=0, ±1 dipole selection rules. The saturation technique has been used to measure the photoionization cross section from three intermediate states 2p53p′ [1/2]1, …
The Study Of The 1s4–2pj Optogalvanic Transients In A Neon Discharge Plasma, Naveed Piracha, R. Feaver, T. Gilani, Rizwan Ahmed, R. Ali, M. Baig
The Study Of The 1s4–2pj Optogalvanic Transients In A Neon Discharge Plasma, Naveed Piracha, R. Feaver, T. Gilani, Rizwan Ahmed, R. Ali, M. Baig
Naveed K. Piracha
Time dependent optogalvanic signals induced by the 1s4→2pj laser excitations have been studied in neon DC plasma. The decay rates related to all the four 1si levels have been derived by fitting the waveforms with a mathematical rate equation model. The temporal signatures of three transitions namely 638.3, 650.7 and 724.5nm related to the 2p7, 2p8 and 2p10 upper levels, respectively, have been found to be different from the rest of the transitions. We relate these effects to the population redistribution of decaying channels and to the processes responsible for the optogalvanic effect.
The Study Of Optogalvanic Effect Associated With The 1s States Of Neon, Naveed Piracha, K. Nesbett, S. Marotta
The Study Of Optogalvanic Effect Associated With The 1s States Of Neon, Naveed Piracha, K. Nesbett, S. Marotta
Naveed K. Piracha
We report on the temporal evolution of the optogalvanic signals in neon using a commercial hollow cathode lamp in conjunction with a Nd:YAG pumped dye laser system. We have recorded transitions excited from each of the neon 1s states over a range of discharge current to investigate the dominant physical processes responsible for the optogalvanic effect in neon discharges. The decay rates associated with the four 1s levels have been obtained using a mathematical rate equation model. A linear relationship between the decay rates and the discharge current has been found and the effective lifetimes and the electron collisional rate …
On The Time-Resolved Optogalvanic Spectra Of Neon And Krypton, Naveed Piracha, K. Nesbett, S. Moten, P. Moeller
On The Time-Resolved Optogalvanic Spectra Of Neon And Krypton, Naveed Piracha, K. Nesbett, S. Moten, P. Moeller
Naveed K. Piracha
In this work time resolved optogalvanic signals associated with transitions excited from the first metastable state of neon and krypton have been studied. These gases have similar energy state configurations and it is of significant interest to study their time resolved optogalvanic waveforms resulting from transitions belonging to the states of same quantum numbers. The experimentally observed optogalvanic signals recorded for different discharge currents have been fitted to a theoretical model to obtain parameters that determine amplitudes, instrumental time constants and decay rates of the 1s levels.
Two-Photon Optogalvanic Spectra Of Argon: Odd Parity Rydberg States, Naveed Piracha, M. Baig, S. Khan, B. Suleman
Two-Photon Optogalvanic Spectra Of Argon: Odd Parity Rydberg States, Naveed Piracha, M. Baig, S. Khan, B. Suleman
Naveed K. Piracha
Extensive new data on the odd-parity, single-colour, two-photon optogalvanic spectra of argon in the visible region is reported using an excimer-pumped dye laser in conjunction with an argon discharge cell. The experimental technique enables us to record a pure two-photon spectrum in a region which is dominated by one-photon transitions. A large number of two-photon transitions, originating from the two metastable states [...] and [...] to the excited states of configurations [...] (J=0, 2) and [...] (J = 0 - 4) of argon, has been recorded and arranged into 10 Rydberg series. The interchannel interactions among the [...] and the …