Direct-current coil gun suitable for various guns and cannons

The magnetic effect of current, the direct-current permanent magnet linear motor and the electromagnet principle are combined and applied to the field of electromagnetic guns, and the direct-current coil gun capable of controlling megaampere-level current to be below hundred ampere-level current to achieve and exceed the performance of a rail gun is invented. The whole length of a gun barrel is designed into a plurality of electromagnets with continuously and alternately changing magnetic poles, the problem is solved by using a proximity switch non-contact mode instead of an electric brush reversing principle of a direct current motor, and the permanent magnet shell with the invariable magnetic pole direction is attracted and repelled by using the characteristics that a magnetic induction line is preferred, the magnetic resistance is minimum, the optimal path is closed, and magnetic induction lines are densest in a minimum magnetic resistance area under a coil. The repulsive force of the magnet is fully utili