Numerical investigation of a hydrogen dipolar plasma source sustained by electron cyclotron resonance

The plasma evolution and physical mechanisms are crucial for optimizing the performance of dipolar microwave hydrogen plasma source (DMHPS). A two-dimensional, self-consistent model of a DMHPS sustained by electron cyclotron resonance (ECR) is developed. Due to the presence of a static magnetic field, the electron transport coefficients and plasma conductivity are represented as full tensors. These highly anisotropic transport properties lead to the strong energy transfer along magnetic field lines. The computed electron density and temperature show good agreements with experimental results. During the transition from the underdense to the overdense regime (where the electron density exceeds the critical density), the deposition of microwave power shifts from the ECR surface to the off-ECR or upper-hybrid resonance (UHR) region. The temperature of hot electrons decreases rapidly with increasing electron density. The polarity reversal of the radial component of the electric field arises from the ambipolar field. Energy from the microwave field is transferred to the ambipolar electric field, resulting in electrostatic heating.