High-frequency AC breakdown in near-atmospheric pressure noble gasses

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Electron bunch-length measurements using grating enhanced ponderomotive scattering

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Main features of AC ignition of HID lamps

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AC ignition of HID lamps

Our aim was to examine the starting behaviour of mid-pressure argon discharges in pin-pin (point-to-point) geometry, typically used in HID lamps. We focused our work on AC ignition of 300 and 700 mbar Ar discharges in Philips 70W standard burners. Frequency was varied between 200 kHz and 1 MHz. In this paper, we present several key features of an AC-driven discharge ignition

Statistical time lags in ac discharges

The paper presents statistical time lags measured for breakdown events in near-atmospheric pressure argon and xenon. Ac voltage at 100, 400 and 800 kHz was used to drive the breakdown processes, and the voltage amplitude slope was varied between 10 and 1280 V ms-1. The values obtained for the statistical time lags are roughly between 1 and 150 ms. It is shown that the statistical time lags in ac-driven discharges follow the same general trends as the discharges driven by voltage of monotonic slope. In addition, the validity of the Cobine–Easton expression is tested at an alternating voltage form

AC ignition of HID lamps –statistical and formative lag times

Noble gas discharges are typically used in lighting applications, under a very large range of conditions. A lot of modelling and experimental work has already been done in order to describe the starting behaviour of lamps. Focusing on high-pressure systems, high voltages needed for the ignition of lamps pose a problem. The purpose of this work is to examine the mechanisms of AC lamp ignition, which was already proven to be efficient in lowering HID lamp ignition voltage. More specifically, we use electrical measurements and observe the discharge by means of iCCD imaging to determine the lag times associated with AC lamp ignition. We use sine voltage with frequencies ranging from 60 kHz to 1 MHz, with various rise rates of the voltage amplitudes. Lamps we use are standard 70 W Philips burners, filled with 0.3 or 0.7 bar Argon or Xenon. We find that the statistical lag times in the system can be as long as 0.15 s and that they are at least two orders of magnitude longer than formative lag times

Polarization-dependent ponderomotive force in a standing wave

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Ac breakdown in near-atmospheric pressure noble gases: I. Experiment

Ac-driven breakdown processes have been explored much less than the pulsed or dc breakdown, even though they have possible applications in industry. This paper focuses on the frequency range between 60 kHz and 1 MHz, at a pin–pin electrode geometry and gap lengths of 4 or 7 mm. The breakdown process was examined in argon and xenon at 0.3 and 0.7 bar. We used electrical and optical measurements to characterize the breakdown process, to observe the influence of frequency change and the effect of ignition enhancers—UV irradiation and radioactive material