Inductor & Transformer
The poloidal field inductor and transformer surpass toroidal field inductor and transformer. The reluctance of the poloidal field inductor and transformer are less than those of toroidal field inductor and transformer. On the analogy between reluctance of magnetic circuit and resistance of current circuit, the reluctance is proportional to the length of magnetic circuit and inversely proportional to the area of magnetic circuit. The magnetic circuit of a small reluctance can easily build up a magnetic field. While the magnetic circuit length of the poloidal field inductor and transformer is less than that of toroidal field inductor and transformer, the magnetic circuit area of the poloidal field inductor and transformer is greater than that of toroidal field inductor and transformer.