Spatio-temporal dynamics of a microsecond pulsed glow discharge

As a type of pulsed discharges, microsecond pulsed glow discharges (µs-PGD) brought an improvement of the analytical characteristics of the GD sources for several optical and mass spectrometric methods. Advantages of µs-PGD are increasing signal outputs and the temporal resolution of analytical species from concomitant species in the discharge plasma. Another benefit of µs-PGD is that even though instantaneous power is higher, the average power can be significantly lower than in millisecond PGD, resulting in reduced thermal stress of the analyzing sample. The higher instantaneous power of the µs-PGD is closely related to the so- called “pre-peak”, a spike in the electrical current and a spike of plasma radiation at the leading edge of the discharge pulse. The radiation pre-peak, together with an increased radiation in afterglow for some spectral lines (after-peak) are responsible for the improvement of the analytical characteristics of the PGD in optical emission spectrometry. Here we present results of measurement of spatio-temporal distributions of several atomic spectral lines of copper in a Grimm-type µs-PGD.To run discharge, a laboratory made pulsed voltage power supply were used, with capability to ensure up to 300 W per pulse. For a space resolved emission measurements we used optical system contained of quartz lens and 1m- Spectrometer equipped with ICCD camera. Following the suggestion (Alberts et al al, 2010) measurements have done by using the frequency of 5 kHz and the pulse width of 30 μs. 170 μs off-time allows to investigate near afterglow of the discharge.At the line intensity distribution, three characteristic phases (or the discharge regimes) can be resolved: the pre-peak (0 – 5 µs) caused by fast increase of the applied voltage; steady-state (5 – 30 µs) during it the voltage has a constant value, and the afterglow when the voltage is switched off, see Fig. 1. There are the two space regions, characteristic for the discharge: the CF which bor ... - FULL TEXT available in PDF.