The Design Of A Super Low Frequency Rectangular Pulse High Voltage Power Supply

To meet the needs of the development of modern optical technology higher requirements have been raised with the laser light. Broadening the range of the output wavelength is one of those requirements. One of the most effective and feasible ways of broadening the range of the output wavelength is using frequency conversion of non-linear Crystal under the condition of phase matching. External electric field polarization is one of the ways that can realize the phase matching. So we need a special high voltage power supply which can output rectangle waveform pulse and the pulse width and range and frequency can be modulated. The main technology indexes are as the follows. The frequency can be modulated from lHz to 10Hz and the output voltage 2kV to 20kV.The output pulse current is above 300 microampere and pulse width can also be modulated from 5%—95% period . The linear character and stabilization of the output voltage can meet the requirement of electrical polarization method.At the present time most low frequency high voltage power supply usually made by means of increasing voltage with pulse transformer or cutting waveform of direct current with switch which can endure reverse high voltage. But because of the big volume of the transformer and the difficulty of producing high quality switches that can endure reverse high voltage. The two means can not meet the technology requirement of the new type power supply. To overcome the disadvantages of the generic means the basic implement scheme was simply described as follows. The velocity and running time of the step electromotor were controlled by the single chip computer and displayed by the LED. Through keyboard we can set parameters such as velocity and time. One of the two timer's overflow frequency decide the frequency of the output pulse of the single chip computer and the later frequency decide the velocity of the step electromotor ,while the other low frequency overflow timer decide the time of the output pulse. The two timers together control the running of the step electromotor. And the frequency of the high voltage pulse can modulated by adjusting velocity of the step electromotor, that is adjusting overflow frequency of one timer .The time of the continuance of the high voltage pulse decided by the rotating time of step electromotor. In order to reduce shake of the step electromotor working in the low frequency status a kind of driver with subdivision function was adopted. By this way the noise can be reduced a lot. The fisbee rotates under the driving of the motor. The distance of the two fixed spark switched fixed on the fisbee decide the pulse width of the high voltage power supply. By adjusting that distancecan modulate the pulse width of the high voltage power supply. Changing the output voltage of the booster can change the output voltage of high voltage DC power supply, thus to change the value of the pulse. The linear character and stabilization of the output voltage can meet the requirement of electrical polarization method by using high voltage pulse capacitance.Many experiments have been performed on LjNbO3 crystal by using this power supply and expected results were obtained. Under appropriate experimental conditions this power supply can meet the needs of polarizing nonlinear crystals with various thicknesses by electrical polarization method.