In recent years, with the rapid development of China's economy and the accelerating urbanization process, the population of large and medium-sized cities has expanded rapidly, and the contradiction between urban supply and demand has become increasingly prominent. Because urban rail transit, especially the subway, has the advantages of large volume, fast speed, safety, and land use, it is increasingly favored by more and more urban planners. As of March 2013, 35 cities in China have started planning and construction of rail transit. China's subway has entered a stage of rapid development. It is estimated that the national investment will reach 1.5 trillion, and a large number of urban rail transit systems will gradually become consumed. Large electric energy. The energy consumption of subway operation is mainly concentrated in three aspects: traction locomotive, interior lighting and air conditioning system. At present, the various technologies of traction locomotives and air-conditioning systems have matured, and related new technologies cannot be applied on a large scale in completed subways, and the energy-saving potential is not large. Due to the inability to apply natural light in the subway environment, artificial light sources must be used for 24h illumination in the car, platform and passage. The energy consumption of the internal lighting system is even higher than that of the air conditioning system. Therefore, the interior lighting that can further tap the energy saving potential in the subway system is [1].
High-efficiency light source is the primary factor of lighting energy saving. According to the needs of urban track lighting, subway lighting source should have long life, low energy consumption, high reliability, good color rendering and no stroboscopic. Refer to GB50034-2004 "Architectural Lighting Design Standards", vigorously promote green lighting, advocate energy conservation, and improve lighting energy efficiency. Lighting products choose high-efficiency, energy-saving, long-life lamps, such as LED lamps, electrodeless lamps, etc. [2]. Therefore, energy-saving and environmentally friendly green lighting sources such as induction lamps and LED lamps will become popular sources of urban rail lighting. Compared with LED, the electrodeless lamp has the advantages of easy heat dissipation, large single-unit power, no stroboscopic, etc., and its electromagnetic interference problem can also improve the working stability of the high-frequency generator, add a metal shielded casing to the generator, and provide a bubble. The shell increases the conductive metal film to effectively reduce [3]. The inductively coupled inductive lamp is different from the capacitively coupled dielectric barrier discharge [4]. The former is an inductive discharge during normal operation and the latter is a capacitive discharge. The energy-saving effect of the inductive discharge electrodeless lamp depends on the level of its light effect, the higher the light efficiency, the better the energy saving effect. The level of light effect is related to the starting, stability [5] and discharge parameters [6] of the electrodeless lamp. In particular, the starting process of the electrodeless lamp determines whether the electrodeless lamp can be lit. It is the premise that the electrodeless lamp can be widely applied and improved in light efficiency. Therefore, it is of great significance to carry out in-depth research. In this paper, high-speed cameras and oscilloscopes are used to study the startup process of induction lamps, and some results of the process are discussed.
1 experimental device
In order to study the starting process of the electrodeless lamp, an experiment similar to the QL85 type electrodeless lamp was used. The principle of the experimental device is shown in Fig. 1. Power frequency mains generates high frequency current of 2.65MHz via high frequency electronic ballast. When the high frequency current flows through the coupler coil, a changing electromagnetic field is generated around the coupler to transfer electric energy into the electrodeless bulb. The electrons in the internal discharge space of the body collide with the low-pressure Ar gas molecules in the bubble when the electron energy is high enough to cause the gas in the bulb to avalanche and ionize to form a plasma. The ultraviolet photon emitted by the plasma excitation transition excites the phosphor on the inner wall of the bulb to generate visible light. The size of the discharge area during the activation process in the bubble and the intensity of the light emission are determined based on the photograph of the discharge. The discharge picture was taken by a Phantom V12 camera produced by VRI USA. The full-frame resolution of the camera was 1280×1280 pixels, the shortest exposure time was 1 μs, and the average correspondence of light in the 300-800 nm band was 0.26 A/W. The camera is 3 meters. Tektronix TCPA300 current probe (with 10A/V range), Tektronix P6015A high voltage probe and Tektronix TPS 2014 (100MHz, 1Gs/s) Four-channel oscilloscope measures discharge voltage, current and power output at the output of the electronic ballast. In addition, a photoresistor was placed at a distance of 30 cm from the surface of the bubble body to connect the change with a coaxial cable to the oscilloscope port to record changes in the light intensity signal (not shown).
Figure 1 Schematic diagram of the experimental device