| Summary: | 碩士 === 國立東華大學 === 電機工程學系 === 95 === With the continual growing demand of the flat panel display, it has become a crucial demand of how to save the cost in flat panel display manufacturing. In the future large-scale panel process, the traditional rubbing alignment will encounter cost and technical issues, such as alignment uniformity. However, plasma beam alignment has no these limitations, and can be developed as the next generation potential alignment technology for the strong points of non-contacting, flexible uniformity control, flexible LC pre-tile angle control, etc. Thus we believe plasma beam alignment will become the mainstream technique of LC alignment in the next generation.
In this work, we design an anode layer plasma thruster by theoretical considerations which are acceleration channel and magnetic circuit. The channel length must satisfy the conditions of (1) channel length between ion Larmor radius and electron Larmor radius (2) channel width bigger than the channel length. According above, we design a thruster with the dimensions: inner diameter 62mm, outer diameter 88mm, channel width 13mm, and channel length 8mm. The other important factor for the optimization is the magnetic field distribution along the short acceleration channel. The magnetic circuit is carried out by one inner electromagnetic magnetic pole and four outer electromagnetic magnetic poles, and simulated by the FEM software-Maxwell package. The necessary cathode is designed as hallow-type with inner tungsten probe inside and stainless steel wall material. Electron beam will concentrate on such cathode.
Finally, we ignite thruster plasma at pressure 8E-4torr, Ar gas flow 5 mg/s, and DC 450V, then measure magnetic field strength by Gauss meter and the plasma parameters by Langmuir probe. The data show that B field has maximum 650 G at exit, and the electron temperature is 7.68eV, the plasma density is
6.928E11 cm-3, and the plasma jet distance is 3.5cm which has space to improve. We also find the electron temperature and density are proportional to B field, and uniform B field can be reached when inner and outer magnetic flux matching.
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