权威例句
Polar capPolar capMagnetic activity in the polar cap—A new indexVariations in the polar cap area during two substorm cyclesF layer ionization patches in the polar capDependence of polar cap potential drop on interplanetary parametersPolar cap electric field structures with a northward interplanetary magnetic fieldGamma-Ray Pulsars: Emission from Extended Polar CAP CascadesA new source of suprathermal O + ions near the dayside polar cap boundaryElectric and magnetic field characteristics of discrete arcs in the polar cap