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Tham khảo tài liệu 'wave propagation 2011 part 15', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Plasma Wave Propagation with Light Emission in a Long Positive Column Discharge 403 Fig. 1. Experimental circuit for measuring the optical signals in CCFL operated with DC or AC electric power supply. The high voltage is supplied to the left side of electrode and the other side is grounded. Measuring points of the optical signal are labeled with . Fig. 2. Oscilloscope signals of lamp voltage lamp current and optical probe intensity for the operation with the DC voltage. The solid bottom line is the zero base line. All the signals are constant on time. 404 Wave Propagation in Materials for Modern Applications Fig. 3 a . Oscilloscope signals of lamp voltage 1.2 kV lamp current 4.2 mA and optical probe intensity for the operation with the rippled-DC voltage as V t Vo A Vsinfflt with A V Vo 10 . The solid bottom line is the zero base line of voltage current and optical intensity. The straight dashed-lines are obtained from the DC operation in Fig. 2. All the signals show the rippled sinusoidal wave with the operation DC frequency 129 kHz and the period of 7.7 ụs. The optical intensity is O t Oo AOsinfflt with AO Oo 10 . Fig. 3 b . The optical signals measured at points when the luminance at is 10 000 cd m1 for the operation with the rippled-DC voltage as shown in Fig. 3 a . The propagation time of optical emission from to is tp 1.82 ụs. The propagation velocity is Wp 3.35 105 m s traveling the distance 610 mm from to . During the propagation the optical intensity decays slightly with the characteristic decay time tD 22 ụs. Plasma Wave Propagation with Light Emission in a Long Positive Column Discharge 405 C 22pF rx a b a 3 b High Voltage Probe Optical Probe Oscilloscope Current probe _ Osin27r O Fig. 4. Experimental circuit for measuring the optical signals at points along the CCFL. Lamp length is 900 mm with 220 mm between each point and 880 mm between points of and . Fig. 5. Current and voltage curves with the applied voltage Va and the lamp voltage Vb measured at .
