Design And Tests Of Interferometer System For Keda Torus EXperiment Using Terahertz Solid-state Diode

The diagnostic of electron density is essentially meaningful for fusion plasma. In the fusion reaction, the whole reactor is maintained and operated on basis of the electron density. Meanwhile, the diagnostic of electron density is important for the research of turbulence in plasma. KTX (Keda Torus eXperiment) is a newly-built Reversed-Field Pinch device, which needs a proper method to diagnostic the electron density. Of all the ways to diagnostic the density, interferometer is the simplest one, and it is a reliable technique to measure the electron density profile with high spatial and temporal resolution while there is no influence on plasma during the diagnostic. These characteristic make interferometer the most popular method in fusion plasma.Traditionally, the Far-infrared (FIR) lasers are widely used in the interferometer diagnostic system on many fusion reactor. However, there are some drawbacks, such as, the huge energy consumption, the high price, the massive size. These drawbackslimit their application, as the cost is relatively high and the application is inconvenient. According to the principle of gaseous laser, the resonance is very sensitive with temperature. So water cooling and thermostatic chamber are needed to keep the temperature stable, and a large scale of labor is required. However, the solid-state source with cheaper price and more suitable size, is free from these problems which is a perfect substitute for the FIR laser. These advantages show that it is a promising and meaningful try to apply the solid-state sources to the interferometer diagnostic system. Although the power is relatively small, as the development of diode sensibility, the technique of mixers is developing as well which make the application of solid-state sources possible.In the thesis, the design of KTX interferometer diagnostic system and some bench tests plan is introduced, including the schematic design, the bench tests of the grid mesh, the function test of the whole system and the design of KTX interferometer system. As Gaussian beam transmitting in the air, the light spot grow bigger along with the distance grow longer. In the design of light path, the light spot should be considered to calculate the optimum size of each optical element. For the whole interferometer system, the tests of each optical elements are extremely important, so there are a series of bench tests arranged to test optical elements and the function of the whole system.