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An experimental research on multi-stable mode transitions and hysteresis loops in a high magnetic field helicon wave plasma source is conducted by adjusting matching network parameters. The correspondence relation between the electric circuit and plasma parameters is explored by measuring the plasma absorbed power, plasma electron density, and power transfer efficiency. The details of mode transitions are recorded by measuring the transmission coefficient to understand the feedback effects on the electric circuit from the plasma. Three discharge modes are observed in helicon discharge: the capacitively coupling mode (E mode), the inductively coupling mode (H mode), and the wave coupling mode (W mode). When the plasma absorbed power increases, the discharge mode directly jumps from the E mode to the W mode, while the discharge mode jumps in the order of W–H–E when the plasma absorbed power decreases. In such multi-stable systems, the plasma may be in different modes under the same set of circuit conditions. Hysteresis loops exist even when the dissipative power in the matching network is subtracted, which indicates that the main cause of hysteresis is nonlinearities inside the plasma. [ABSTRACT FROM AUTHOR]

The Space Plasma Environment Research Facility (SPERF) being built in Harbin provides a laboratory platform for research on space plasma. The vacuum system, as an essential subsystem, is designed to set up an experimental vacuum environment for plasma experiments. However, the SPERF with a large volume of 2.315 × 10 5 l contains a lot of outgassing loads and hundreds of interfaces, which poses a big challenge for high vacuum acquisition. In addition, the plasma experiments on the SPERF require a pure background vacuum environment. In this study, the vacuum system is designed to meet the experimental requirements for the vacuum environment, with emphasis on the pumping system configuration and the vacuum acquisition process. Benefiting from the great construction techniques and advanced configuration of the pumping system, the target ultimate pressure of 1.0 × 10 − 4 Pa in the chamber can be obtained within 24 h and the leakage rate of the vacuum chamber is 30 % smaller than the target value. It is significant that the high vacuum environment is efficiently achieved in such a big chamber, and the design may throw some new light on constructing other similar large-scale vacuum systems. [ABSTRACT FROM AUTHOR]

The Space Plasma Environment Research Facility (SPERF) is a ground-simulation facility, which is under construction, for studying space plasma. It includes a terrestrial space plasma environment simulation system (T-S system) and near-space plasma environment simulation system (N-S system). Plasma experiments performed on the SPERF require the functional cooperation of each subsystem. Therefore, the Experimental Physics and Industrial Control System (EPICS) was selected as the middleware in the engineering phase. Currently, the architecture of a vacuum-centralized control system is almost complete, and it is in the process of debugging. The application of EPICS in the SPERF vacuum-centralized control system has laid a structural foundation for the integration of other control systems and provides a test bed. In this study, we describe the implementation of EPICS for the SPERF vacuum-centralized control system, a procedure from hardware drivers realizing operation panels. [ABSTRACT FROM AUTHOR]

The Space Plasma Environment Research Facility (SPERF) is a ground simulation user facility for studying the space plasma physical processes. This study presents the design and construction of a vacuum control system for the SPERF to set up an appropriate vacuum environment for plasma experiments, including the terrestrial space and near space vacuum control systems. Based on the requirements of remote automation, distributed control, centralized management, high reliability, expansibility, and safety, the architecture of the vacuum control system has been divided into three levels. Among these, the local level is the most essential part of the control system, which adopts the programmable logical controller (PLC) with Siemens S7-1500 CPU as the core. The PLC supports multiple communication protocols and can accurately control and monitor the actuators in the process of establishing a vacuum environment. Furthermore, it has the ability to communicate and interact with remote upper computers and the central control system through the supervisory control and data acquisition (scada) software developed based on iFix. Based on the architecture of the vacuum control system, the control process for establishing the vacuum environment, including the ultimate vacuum and experimental vacuum, was designed. It is noteworthy that in experimental vacuum acquisition, the injection of working fluid gas is controlled directly by the central control system, considering the different requirements of the terrestrial space and near space systems for the experimental working pressure and flexibility of the experimental vacuum control. The vacuum control system designed in this study provides technical support for the SPERF to perform the plasma experiments successfully. In addition, it offers reference and insights for the design of vacuum control systems in similar large-scale plasma simulation facilities. [ABSTRACT FROM AUTHOR]

The mechanism of acceleration, loss, and wave–particle interaction of energetic particles in the magnetosphere is a research content of the Space Plasma Environment Research Facility, which is being built as a user facility at the Harbin Institute of Technology in China. Two magnetic perturbation coils are used to simulate the magnetic storm distortion and excite Alfvén wave perturbation. A capacitor-based pulsed power supply (PPS) system with a modular design is developed to excite the magnetic perturbation coils to generate the required amplitude and duration of the magnetic field. The two magnetic perturbation coils are the CRDI coil and CRDII coil and are excited by one set of PPSs. The PPS for the CRDI coil consists of two modules and can provide a pulsed current of no less than 132 kA at 0.12 ms when the charging voltage is 20 kV, and the duration of the pulsed current from the peak to 10% of the peak is no more than 0.7 ms. The PPS for the CRDII coil consists of five modules and can provide a pulsed current of no less than 16 kA at 0.45, 0.65, 0.8, 0.95, and 1.1 ms, and the duration of the pulsed current from the peak to 10% of the peak is no more than 4.5 ms. The detailed design of the PPSs has been discussed in this paper, and the discharge test of the PPSs is carried out to verify the design of the PPSs. [ABSTRACT FROM AUTHOR]

The Space Plasma Environment Research Facility currently under construction at the Harbin Institute of Technology in China uses four magnetosheath coils (flux cores) and a dipole coil to generate the magnetic field required for the study on the magnetopause magnetic reconnection. Two groups of magnetopause shape control coils (labeled CK coils) are used to slightly adjust the magnetic field distribution on the magnetopause. A capacitive pulsed power supply (PPS) system with a modular design is developed to excite CK coils. The PPS system consists of six sets of PPS with the same principle and structure, which are used to excite six sub-coils of the CK coils, respectively. Each set of PPS consists of ten modules and one local controller, and each module consists of a charger and discharge unit. Each set of PPS can provide a pulsed current of no less than 400 kA for the corresponding sub-coil at 0.11 ms when the charging voltage is 20 kV, and the duration of the pulsed current from the peak to 10% of the peak is no more than 0.6 ms. The detailed design of the PPS is discussed in this paper, and the discharge test of the PPS is carried out to verify the design of the PPS. Because there are acquisition and control devices in the discharge unit, the electromagnetic interference immunity design is also discussed to ensure the normal operation of the PPS. [ABSTRACT FROM AUTHOR]

A magnet system is used in the SPERF to create the magnetic field configuration for simulating the space plasma environment. In this paper, the parameters of the system are designed to achieve the target fields needed by the scaling laws, and the electromagnetic analysis has been performed to validate the results. A procedure to obtain the parameters is proposed based on the investigation into the physical and technological constraints. The vacuum magnetic fields for studying the 3D magnetic reconnection at the magnetopause, Earth's magnetosphere, and 3D magnetic reconnection driven by a plasma gun are computed. In addition, the engineering complexity is reviewed in brief. This research is crucial to the construction of the SPERF, and it is valuable to designing the magnets applied in other fields. [ABSTRACT FROM AUTHOR]

A one-dimensional plasma photonic crystal, which consists of periodically alternating layers of quartz discharge tubes and air, is proved to have a special photonic bandgap. It is found that in the absence of plasma, the quartz tube array can give rise to a bandgap within a fixed frequency band. Interestingly, both effective medium theory and experimental results reveal that such a bandgap can be closed in the existence of the plasma with an appropriate plasma density and can be reopened as the increase in the plasma density. The unique behavior of the bandgap also depends on the collision frequency of the plasma. To describe these phenomena, an air-like plasma frequency is defined. These studies pave the way for realizing tunable bandgaps in microwave applications. [ABSTRACT FROM AUTHOR]