High-acceleration motors are usually used for studies of hypervelocity
collisions, as weapons, or as mass drivers for spacecraft propulsion. They
are usually of the AC linear induction motor (LIM) design with an active
three-phase winding on one side of the air-gap and a passive conductor
plate on the other side. However, the direct current homopolar linear motor
railgun is another high acceleration linear motor design.
The low-acceleration, high speed and high power motors are usually of the
linear synchronous motor (LSM) design, with an active winding on one
side of the air-gap and an array of alternate-pole magnets on the other
side. These magnets can be permanent magnets or energized magnets.
The Shanghai Transrapid motor is an LSM.