Chen Zhaoquan

A Novel Structure of Slot-Antenna Array for Producing Large-Area Planar Surface-Wave Plasmas

The principle of surface wave plasma discharge in a rectangular cavity is introduced and the distribution of the electromagnetic field within a rectangular waveguide is analysed. A novel structure of a slot antenna array is presented. In comparison with the traditional slotantenna, it is shown that the designed slot antenna array can excite effectively the surface wave coupling into the chamber, and generate a stable large-area high-density plasma. These results are useful for exploring the optimized design of the slot-antenna for surface wave plasmas.

Numerical Reproduction of Spatio-Temporal Evolution of Surface Plasmon Polaritons at Dielectric-Plasma Interface

Discharges in planar-type overdense plasmas caused by resonant excitation of surface plasmon polaritons (SPPs) are presented. The spatio-temporal evolution of surface waves of SPPs at the dielectric-plasma interface is reproduced numerically. It is found that different discharge light patterns are excited by different spatio-temporal wave fields. Moreover, the corrugation surface included in the proposed plasma sources plays a significant role in producing large-area uniform plasmas.

Surface Wave Analysis of Planar-Type Overdense Plasma with Surface Plasmon Polariton Resonance

Surface waves (SWs) in planar-type overdense plasmas are analyzed and the invariable SW mode caused by the resonant excitation of surface plasmon polaritons (SPPs) is presented. It is found that the electric field peaks at the location where the plasma density equals the cut-off density while the plasma density gradient and the collision rate have different influences on the field amplitude and the peaks width. Moreover, the mode conversion between SW of SPPs and electron plasma waves play a significant role in production of overdense plasma.

Self-consistent three-dimensional modeling and simulation of large-scale rectangular surface-wave plasma source

A self-consistent and three-dimensional (3D) model of argon discharge in a large-scale rectangular surface-wave plasma (SWP) source is presented in this paper, which is based on the finite-difference time-domain (FDTD) approximation to Maxwells equations self-consistently coupled with a fluid model for plasma evolution. The discharge characteristics at an input microwave power of 1200 W and a filling gas pressure of 50 Pa in the SWP source are analyzed. The simulation shows the time evolution of deposited power density at different stages, and the 3D distributions of electron density and temperature in the chamber at steady state. In addition, the results show that there is a peak of plasma density approximately at a vertical distance of 3 cm from the quartz window.

Estimation of Plasma Density by Surface Plasmons for Surface-Wave Plasmas

An estimation method of plasma density based on surface plasmons theory for surface-wave plasmas is proposed. The number of standing-wave is obtained directly from the discharge image, and the propagation constant is calculated with the trim size of the apparatus in this method, then plasma density can be determined with the value of 9.1 × 1017 m−3. Plasma density is measured using a Langmuir probe, the value is 8.1 × 1017 m−3 which is very close to the predicted value of surface plasmons theory. Numerical simulation is used to check the number of standing-wave by the finite-difference time-domain (FDTD) method also. All results are compatible both of theoretical analysis and experimental measurement.

Observation of Hot Electrons in Surface-Wave Plasmas Excited by Surface Plasmon Polaritons

The electron energy distribution functions (EEDFs) are studied in the planar-type surface-wave plasma (SWP) caused by resonant excitation of surface plasmon polaritons (SPPs) using a single cylindrical probe. Sustained plasma characteristics can be considered as a bi-Maxwellian EEDF, which correspond to a superposition of the bulk low-temperature electron and the high-energy electron beam-like part. The beam component energy is pronounced at about 10eV but the bulk part is lower than 3.5eV. The hot electrons included in the proposed plasmas play a significant role in plasma heating and further affect the discharge chemistry.

Three-Dimensional Numerical Simulation of Surface-Wave Plasma Source

A three-dimensional model of a surface-wave plasma (SWP) source is built numerically using the finite-difference time-domain (FDTD) method to investigate the structure of the surface wave propagation along the plasma-dielectric interface and the distributions of electromagnetic fields in the whole system. A good-performance excitation source technique for the waveguide which is pivotal to the simulation is presented. The technique can avoid the dc distortions of magnetic fields caused by the forcing electric wall. An example of simulation is given to confirm the existence of the surface waves. The simulation also shows that the code developed is a useful tool in the computer-aided design of the antenna of the SWP source.

Character Diagnosis for Surface-Wave Plasmas Excited by Surface Plasmon Polaritons

The plasma parameters of planar-type surface-wave plasmas (SWPs) are diagnosed based on the resonant excitation of surface plasmon polaritons (SPPs). The plasma parameter distributions are obtained by changing the discharge conditions of gas pressure and incident power. The measured experimental results show that the plasma near the heating layer is excited by surface waves of SPPs while the plasma located downstream originates from diffusion Moreover, the influence of high-frequency oscillations plays a significant role in producing the proposed SWPs with bi-Maxwellian electron energy distributions.

High-power microwave discharge for producing large-area surface-wave plasmas

The theory of surface-wave discharge is introduced. A novel structure of the slot antenna array is designed in this paper, and its excitation is numerical analyzed using dipole-antenna array model and FDTD method, respectively. A microwave discharge experiment is operated with this slot-antenna array, and a numerical simulation is also done with FDTD code using the parameter of plasma from experimental measurement. It is found that the designed slot antenna array can excite effectively the microwave coupling into the cavity, and produce the stable large-area high-density plasma.