One of the main technical parameters of light emitting devices is their service life. The service life and stability of light radiation during operation determine the operating conditions of light sources. By the example of barrier discharge excilamps based on KrCl* (222 nm) and XeBr* (282 nm) exciplex molecules, an optoelectronic method for stabilizing excilamp UV radiation is proposed. The method consists in autocorrecting the radiation power of the excilamps using a UV radiation sensor and an electronic feedback that regulates the power of the excilamps. During of tests for the service life of KrCl and XeBr excilamps, the dependences of the change in the excilamp radiation power on time in a continuous mode of operation were obtained. A new approach to describing the reliability of excilamp operation is discussed. It is shown that instead of such a parameter of light-emitting devices as a useful service life, it is necessary to use a new quantitative characteristic, which is proposed to be called the guaranteed service life of the stable operation of the excilamp.
The paper demonstrates the possibility of studying blue jets in laboratory apokamp discharges as a source of blue streamers that move upward from the discharge channel. Research data are presented on the formation of such streamers in low-pressure air at a voltage of tens of kilovolts, showing for the first time that they do arise at low (∼8 Hz) pulse repetition frequencies under pressures at which gigantic blue jets develop 10–20 km above the Earth. At a voltage of positive polarity with an amplitude of 33 kV, the streamer velocity in a pulsed apokamp discharge reaches 560 km/s. When applying microsecond voltage pulses of amplitude 15 kV with a repetition frequency of 50 kHz, the length of streamers ranges to more than 120 cm.
Here we present research data demonstrating how crop seeds response to ultraviolet produced by a barrier-discharge XeCl* excilamp with a wavelength of 290–320 nm (82–88 %). The data show that presowing ultraviolet treatment is stimulatory to seed germination and plant growth. Ultraviolet treatment increases the seed germinability by 20–30 % and the plant fresh weight by 54 %, compared to untreated control samples, and provides a developed root system with long twisted segments. The research results are encouraging for upgrading the UV technology to larger-scale seed irradiation.
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