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Generation of ionospheric-like plasma is important for laboratory investigations of ionospheric physics. In this work, the design and fabrication of a magnetic filter source for the ground simulation of ionospheric-like low density plasma are presented. Four groups of permanent magnets were placed at different regions to form a magnetic filter configuration, and filaments were used to produce the low-density plasmas. Operating with adjustable plasma source conditions can generate plasmas with variable density and energy similar to those of the ionosphere, which were measured using tailor-made plasma diagnostic tools. The results indicate that homogeneous distributed low-density plasmas on the order of 105 cm−3 were produced using the plasma source. In addition, ion and electron energies that are similar to those of the actual ionosphere were also achieved. Based on the plasma source, ionospheric plasma physics can be investigated in a controlled manner in the laboratory. In addition, it can also be extended to the calibration and testing of payloads for ionospheric plasma measurement before launching. [ABSTRACT FROM AUTHOR]

Molecular ions are relatively cold in the E region ionosphere; however, they can upwell to the magnetosphere during geomagnetically active times. Resonance between electrostatic ion cyclotron (EIC) waves is a potential pathway to energize molecular ions. In this work, the E region ionospheric plasma was modeled in the laboratory, and EIC waves were excited by a nonuniform field‐aligned current. The EIC wave was excited even when the ion neutral collision frequency is much higher than the ion cyclotron frequency, and the fundamental frequency was observed to be below the ion cyclotron frequency. In addition, the wave dispersion of the collisional EIC wave was calculated, which shows a consistent trend with experimental results as the collisions increasing. Therefore, this work suggests that EIC waves can be excited in the E region ionospheric‐like plasma, which can support the explanation of the energization of molecular ions in the E region ionosphere. Plain Language Summary: Spacecraft observed the presence of molecular ions in the topside ionosphere (600–1,000 km) and the magnetosphere during geomagnetically active times, and the potential mechanisms responsible for the acceleration of these molecular ions are still not fully understood. The resonance between electrostatic ion cyclotron (EIC) waves and molecular ions is a potential pathway to energize the molecular ions. However, most previous works on EIC waves were studied in collisionless plasma similar to the magnetospheric plasma, which is different from the E region ionospheric plasma. A typical characteristic of E region ionospheric plasma is the partially ionized effect, which introduces new physical processes that do not occur in collisionless plasmas. In this work, strong collisions that occurred in the E region ionosphere were simulated in the laboratory, and the current‐driven electrostatic ion cyclotron waves were observed in the modeled ionosphere. It is found that electrostatic ion cyclotron waves can be generated in the E region ionospheric‐like plasma. This work provides solid experimental evidence that electrostatic ion cyclotron instability can exist in weakly ionized plasmas of the E region ionosphere, and can be applied to explain the transverse ion heating of bulk ions in the bottomside ionosphere. Key Points: The E region ionospheric‐like collisional plasma was modeled in the laboratoryEIC waves were excited by field aligned current in the ionospheric‐like plasmaThis work can be applied to explain the energization of molecular ions in the E region ionosphere [ABSTRACT FROM AUTHOR]

In this work, an experimental design for generation of the controllable electron density gradient is achieved through a large area oxide coated cathode and two stainless meshes. The large area oxide coated cathode is adopted to produce a large area, uniform and high density plasma, and these two metal meshes are specially designed to control the density and potential of the plasma. A boundary layer with independent electron density gradient and uniform plasma potential is subsequently generated. The controllable electron density gradient can be achieved, and the accompanied electric field can be compensated simultaneously using this design, which could be potentially extended to study the excitation of the plasma instabilities when the strong plasma density gradient exists. [ABSTRACT FROM AUTHOR]

In this work, we report an experimental observation of the inhomogeneous energy density driven instability (IEDDI) independently excited by the electron density gradient. This was achieved using a novel design which could generate a controllable electron density gradient, while the self-consistent electric field accompanied with the electron density gradient can be simultaneously compensated. Broadband wave mode in the ion cyclotron frequency range was excited, which was further experimentally identified as the IEDDI. This result suggests that the IEDDI can be independently excited by the electron density gradient, which could be extended to explain the satellite observations of the broadband extremely low frequency waves in the auroral plasmas where the strong plasma density inhomogeneities exist. [ABSTRACT FROM AUTHOR]

Ionospheric heating by high‐power electromagnetic waves is a powerful and efficient tool to study plasma physics as the ionosphere is used as a nature plasma laboratory. An important and long‐standing issue is how to improve the heating efficiency. It is difficult to uncover all the underlying physical processes that influence the heating efficiency in actual ionospheric experiments. Therefore, controlled experiments have been designed and conducted in a laboratory plasma facility to study the high‐frequency heating processes in an ionospheric‐like collisional plasma. The energy of the injected wave was transferred into the plasma through nonlinear interactions, such as the parametric decay instability (PDI). Our results suggest that the existing background wave mode could significantly decrease the excitation threshold of the parametric instability, indicating that the PDI can be much easily excited. Plain Language Summary: The ionosphere, the ionized part of Earth's upper atmosphere from about 60 to 1,000 km, has a significant impact on daily activities of humankind. Since the 1970s, ionospheric heating by high‐power high‐frequency (HF) waves has been widely recognized as a powerful tool to artificially modify the ionosphere. Many important physical processes are also studied as the ionosphere is used as a plasma laboratory. On the other hand, such control of ionospheric conditions may have practical applications in radio communication. These ground‐based heating facilities are equipped with high‐power HF transmitters and a variety of diagnostic instruments for monitoring the response of the ionosphere and upper atmosphere. Laboratory modeling of the particular phenomenon in space environment began to develop, and could be applied to understand the physical mechanism of the observations. This work provides an experimental evidence that the existing background wave mode could significantly decrease the excitation threshold of the parametric instability. Therefore, it can be potentially useful to improve efficiency in the active heating experiments. Key Points: Controlled experiments have been performed to study high‐frequency heating processes in an ionospheric‐like collisional plasmaParametric decay instability generated by the electromagnetic wave injection was observed in the laboratoryA background instability can obviously decrease the excitation threshold of the parametric decay instability [ABSTRACT FROM AUTHOR]

Laboratory experiments have contributed significantly to the exploration of the fundamental physics of Earth's and planetary space plasma. In this work, a ground-based plasma device was designed and constructed to study the plasma physics in the Martian boundary layer, where the solar wind plasma directly interacts with the Martian ionospheric plasma, and the underlying physical mechanisms and processes are not fully understood. The solar wind plasma and the Martian ionospheric plasma were simulated using two independent plasma sources. A Kaufman source was used to simulate the low-density, high-velocity solar wind plasma, and a lanthanum hexaboride source was utilized to simulate the high-density, low-velocity Martian ionospheric plasma. Additionally, the crustal magnetic field of Mars was modeled using a rotatable electromagnet. The initial results suggest that the interaction in the Martian boundary layer can be simulated based on the device, and the boundary layer's structure, location, and physical processes can be experimentally studied in the future. • A plasma device was constructed to study the Martian ionosphere in the laboratory. • The elements of Martian ionosphere such as magnetic field and plasmas were modeled. • Boundary layer processes of Martian ionosphere can be investigated using the device. [ABSTRACT FROM AUTHOR]