In this paper, a one-dimension particle-in-cell (PIC) code (EDIPIC) is employed to simulate the parallel-plate ion extraction process under an externally applied electrostatic field, focusing on the analysis of the influence of the initial electron temperature on the extracted ion fluxes to the metal plates during the ion extraction process. Compared with previously published results, the plasma oscillations on a timescale of the electron plasma period, and the excitation of the ion acoustic rarefaction waves resulting from the plasma oscillations originating from both the negative and positive electrodes, are studied for the first time. The modeling results show that both the negative and positive extractors can collect ions due to the plasma oscillations and the propagation of the ion acoustic rarefaction waves. With the increase of the initial electron temperature achieved by keeping other parameters unchanged, on the one hand, both the ion speed and flux to the negative and positive plates increase, which leads to a significant decrease of the ion extraction time, while on the other hand, the ion flux to the positive plate after the formation of a Child-Langmuir sheath is much more sensitive to an increase of the initial electron temperature than that to the negative plate. The PIC simulation results provide a deeper physical understanding of the influence of the initial electron temperature on the characteristics of the entire ion extraction process in a decaying plasma.

Quarry blast acoustic wave (concussion)-response of structures and human annoyanceThe structure of a blast wave with ionization at local-thermodynamic-equilibrium (LTE) is analyzed by using the method of successive approximation to the non-similar solution. It is found that ionization has a significant effect on the decaying speed, and the first-order approximation. Numerical results are presented for plane, cylindrical, and spherical blast waves.

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A cerium (Ce) metal is an important rare earth element that is extremely reactive in air. The Ce surface chemistry can provide insight into actinides and is widely used in nuclear science. Nickel (Ni) is an inert metal with the potential to passivate the Ce surface. The surface and interface properties of a Ce metal with an ultrathin Ni film before and after air exposure have been studied. To prevent air exposure, in situ magnetron sputtering of Ce and Ni metal and surface analysis were carried out. Compared to the ex situ results, the in situ deposition of an Ni film improves the stability of both Ce and Ni. This work provides insight into the impact of the history of the oxidation process to Ce metal properties.