Low Pressure Inductively Coupled Discharge Device And Model To Establish

This thesis focuses on two main topics:1.the inductively coupled H mode(electromagnetic discharge mode) discharge characteristics;2.the inductively coupled E mode(electrostatic discharge mode) and E-H mode transition characteristics;Through the investigation of the two topics,deeper insight of radio-frequency inductively coupled discharge equipment can be gained,which offers the true value for the industry application.The investigation can be summarized from three aspects:ⅰdischarge plasma electromagnetic characteristics;ⅱplasma discharge mechanism;ⅲdischarge mode transition;By modulating the frequency and output power of the RF signal generator and signal magnifier,the Kr-Hg discharge can be induced.In the experiment,H mode and E mode discharge can be distinguished through the luminance,input power and coil current,which can be clearly understood from the basic principle.Through the single-coil method and electromagnetic field distribution(EMFD) model,the electric field distribution and magnetic field distribution in the H mode discharge can be gained radially and axially.Both the E field and B field have exponential profile from the center axis to the inner wall sheath.In the axial direction,both of the distributions have the damped shape,which means the plasma density and energy are dissipated.Using finite difference method and calculated power verification,plasma permeabilityμ,electrical conductivity vectorσ_r+iσ_i and skip depthδcan be gained.By appling the transformer model to H mode discharge,the variation of equivalent resistance and inductance can be gained with the input power and coil current.With the growth of the input power,the plasma resistance rises gradually whereas the inductance decreased.The increase of the resistance means that the rate for electron collision cross section for momentum transferνis faster than the rate for the electron density n_e,which represents the positive resistance characteristics in this kind of inductively coupled plasma.However,when the power of H mode decreases to the mode transition domain,the resistance falls and the inductance increase sharply,which corresponds to the increase ofωL_p / R_p.The power factor also decreases greatly,which means the energy coupling factor decreases sharply.When combining both the two models,the correctness and practicability can be gained.With the further calculation from electrical conductivity expression and the assumptions of the electron temperature and electron collision cross section for momuntum transfer,the electron density,electron temperature and gas temperature can be calculated using the optimum method.The electrical parameters and spectral data are gained through the whole experiment.And from the investigation of E mode discharge and E-H mode transition,the nonlinear effects for the balance of energy absorption and dissipation lead to the hysteresis effects of E-H and H-E mode transition.Through the discharge spectral diagnostics,the relative intensity for Hg435.8nm,Kr 811.3nm,and the rate of Hg365.0nm/Hg312.6nm are analysed.The high level electron density are considerably increased,together with the high level rate.And plasma EEPF is closer to Maxwellian distribution;also the Hg metastable level density is sharply increased when compared with the excited level density and will increase with the current.