Conceptual design of the three-dimensional magnetic field configuration relevant to the magnetopause reconnection in the SPERF

A new ground-based experimental device,the Space Plasma Environment Research Facility (SPERF),is being designed at Harbin Institute of Technology in China,with Asymmetric REconnection eXperiment-3 Dimensional (AREX-3D) as one of the experimental components to study the asymmetric reconnection dynamics relevant to the interaction between the interplanetary and magnetospheric plasmas.The asymmetry in the designed magnetic reconnection process not only refers to the distinct plasma parameters designed for the two upstream regions across the current sheet,but also refers to the inhomogeneity in the direction along the current sheet resulting from the designed 3D magnetic field geometry.These two asymmetries are fundamental features of the reconnection process at the Earth's magnetopause.In experiment,the reconnection process is driven by a set of flux cores through coil-currentramp-up from the 'magnetosheath-side' to interact with a dipole magnetic field generated by the Dipole Research EXperiment (DREX) coil on the 'magnetosphere-side'.The AREX-3D will be able to investigate a range of important reconnection issues in 3D magnetic field geometry that is relevant to the Earth's magnetopause.A wide range of plasma parameters can be achieved through inductive plasma generation with flux cores on the 'magnetosheath-side' and electron cyclotron resonance (ECR) with microwave sources on the 'magnetosphere-side',e.g.high (low) plasma density at experimental magnetosheath (dipole) side.Different reconnection regimes and geometries can be produced by adjusting plasma parameters and coil setups as well as coil current waveforms.The three-dimensional magnetic field configurations in the SPERF relevant to the dayside magnetopause reconnection are discussed in detail.