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This work made an in-depth study on the transport of B, Al and Ag ions in an inductively coupled plasma-Si system. The plasma-stimulated impurity ion transport is demonstrated to be described by an implantation-diffusion two-step process rather than a pure diffusion process reported previously. The first step is impurity ion implantation under sheath voltage induced by plasma, which determines the impurity ion quantity into Si. The second step is plasma-stimulated impurity ion diffusion, which determines impurity ion transport depth in Si. An approximate solution to this implantation-diffusion process is deduced. Plasma-stimulated diffusion coefficients (D) for B, Al and Ag ions in Si are obtained by fitting the measured secondary ion mass spectroscopy concentration profiles with this equation. Furthermore, plasma-stimulated diffusion activation energies for B, Al and Ag ions in p-Si at 0 °C–120 °C are determined to be 0.22, 0.36 and 0.18 eV by Arrhenius plots, which are much lower than diffusion activation energies of 0.4–0.7, 1.2 and 1.15 eV for interstitial B, Al and Ag ions in Si without plasma reported in literatures. The great reduction of diffusion activation energy makes it possible for impurities to diffuse at room temperature or lower temperatures. The view of plasma-stimulated impurity ion transport is of significant importance on semiconductor technology and device degradation research.

The plasma window is a windowless vacuum sealing device that utilizes a cascade arc discharge to isolate regions with different pressures. It was proposed as an alternative to the traditional windowless sealing technology of differential pumping, which greatly improves the sealing efficiency and has been successfully applied in electron beam welding. The discharge channel of the existing plasma window is a small circular hole, referred to as a zero-dimensional plasma window, which has limited applications to its dimensions. In this study, we suggested a one-dimensional (1D) plasma window with a slit discharge channel (cross section: 3 × 35 mm2, length: 60 mm). An arc discharge is realized with the support of an 80 A DC power supply, which can maintain a pressure drop of more than 10 times between the high-pressure and low-pressure ends of the plasma window. A COMSOL-based magneto-hydrodynamic model of the plasma window was established, and simulations were in good agreement with the experimental results. The pressure drop in the plasma window caused by argon plasma has also been theoretically analyzed and discussed. The feasibility of a 1D plasma window to achieve vacuum isolation was verified theoretically, numerically, and experimentally.

The waves in a magnetic null could play important roles during 3D magnetic reconnection. Some preliminary clues in this paper show that the ion Bernstein wave (IBW) may be closely related to transport process in magnetic null region. The magnetic null configuration experiment reported here is set up in a linear helicon plasma device, Peking University plasma test device (PPT). The wave modes with frequencies between the first and third harmonics of local ion cyclotron frequency ( ω ci ) are observed in the separatrix of magnetic null, which are identified as the IBW based on the dispersion relation. Further analysis shows that IBW could drive substantial particle flux across the magnetic separatrix. The theoretical radial particle flux driven by IBW and the measured parallel flow in PPT device are almost on the same order, which shows that IBW may play an important role during 3D reconnection process.

The field-reversed configuration (FRC) is a promising magnetic confinement fusion concept [M. Tuszewski, Nucl. Fusion 28, 2033 (1988)] and is often chosen as the target plasma for magneto inertial fusion [S. A. Slutz and M. R. Gomez, Phys. Plasmas 28, 042707 (2021)]. In FRCs, the toroidal magnetic field is essentially zero, and the poloidal magnetic field ([Formula: see text]) pressure is comparable with the plasma pressure. Applying the traditional [Formula: see text] diagnostics to FRCs is a major challenge because [Formula: see text] is small, and reversal occurs across the core region of FRCs. The laser-driven ion-beam trace probe (LITP) is a newly developing diagnostic method to measure [Formula: see text] and the radial electric field ([Formula: see text]) in tokamak. Here, the principles of using LITP to diagnose [Formula: see text] in FRCs are proposed, verified, and numerically implemented using an iterative method to reconstruct the [Formula: see text] profile. Least square tomography employing a dissipative term is used to solve the nonlinear tomography problem, which arises when applying LITP to the unique FRC magnetic topology. Numerical modeling results show that the relative errors of the reconstruction are mostly below 10%, verifying the feasibility of LITP diagnostics for FRC internal magnetic field measurements. Ion beam orbits and detector arrangements are optimized to meet the experimental requirements of FRCs. LITP can still be applied to diagnose [Formula: see text] in FRCs when there is 5% measurement errors.

Helicon wave plasma sources have the well-known advantages of high efficiency and high plasma density, with broad applications in many areas. The crucial mechanism lies with mode transitions, which has been an outstanding issue for years. We have built a fluid simulation model and further developed the Peking University Helicon Discharge code. The mode transitions, also known as density jumps, of a single-loop antenna discharge are reproduced in simulations for the first time. It is found that large-amplitude standing helicon waves (SHWs) are responsible for the mode transitions, similar to those of a resonant cavity for laser generation. This paper intends to give a complete and quantitative SHW resonance theory to explain the relationship of the mode transitions and the SHWs. The SHW resonance theory reasonably explains several key questions in helicon plasmas, such as mode transition and efficient power absorption, and helps to improve future plasma generation methods.