sawtooth current
1.The ac currents applied can be a sine alternative current with a relevant frequency, or a pulsed current with a suitable pulsed width rand or a discontinuous pulsed current whose width r is very shorter than the intervals between pulses, and or a " sawtooth" pulsed current with the time of ramp phase of the sawtooth is very much shorter than the sawtooth descending time, the ratio of them can be<10-3. The physical model of the ac current drive is analyzed in detail.
