Design Of The Homodyne Interferometer System And The Diagnostic Of Radio Frequency Plasma

The plasma is a complex system with many state parameters.It is an important work in low temperature plasma research to diagnose these parameters including electron density,electron temperature,active particle density,electron energy distribution and so on.In these plasma diagnostic methods,the diagnostic techniques based on the interactions of the electromagnetic wave with plasma have advantages on temporal resolution as a non-intrusive method.A lot of microwave-based diagnostics have been developed according to different interaction mechanisms,and they play an important role in the plasma characteristic studies.In this paper,we designed a homodyne interferometer diagnostic system,and analyzed the performance of the system.The electron density in capacitive coupled plasma?CCP?was measured with the system.We diagnosed the ion characteristics in hydrogen plasma with a Hiden EQP analyzer.Effects of hydrogen addition on ion characteristics in electron cyclotron resonance?ECR?hydrogen plasma were studied.We chose the microwave frequency 10GHz as the working frequency according to the range of the electron density and the plasma dimension,and chose the devices according to the power attenuation in our system,including the horn antennas with lens which were used for transmitting and receiving signal.We measured the electron density in CCP discharge,and the test result showed that the Standard Deviation of phase noisy in the system is about 0.057 degree,the relevant Standard Deviation of the electron density was 3.37×107 cm^-3.When the discharge was sustained using a pulse modulation rf power with the frequency 400 kHz,the duty cycle 50%,and the power 80 W,at a pressure of 100 Pa,the electron density is 5.9×109 cm^-3.It costs about 2.5 ms to reach the maximum electron density,while the rise edge of the power is about 3 ?s.We have investigated the ion characteristics in ECR hydrogen plasma,and effects of hydrogen addition on ion characteristics in hydrogen plasma with a quadrupole mass spectrometer?EQP?.Three kinds of ions,H1+,H2+ and H3+,are detected in hydrogen discharge at the gas pressure of 1Pa,in which the H2+ is the dominant ion.The ion flux increases with the power in the range from 110W to 190W.The ion flux decreases significantly and the ion mean energy increases when H2 beam with the flow of 1 sccm is introduced into the plasma downstream region.