Reasearch & Development Of A High-voltage Nanosecond Pulse Power And Study Of The Characteristics & Sterilization Of Discharged Plasma Using The Pulse Power

Using the pulse power to excite a plasma generation device has some special advantages.It generates vacuum ultraviolet and oxygen atom more efficiently,and its gas temperature could be lower while achieving a higher electron density.In recent years,pulse power excited plasma has already captured an increasing attention from researchers.The application field of pulse power plasma is quite wide,which covers the sterilization,materials treatment,water treatment and so on.The research of pulse power and plasma are two closely related directions.The rising time and falling time has significant influence on the property and application of plasma.For example,a shorter rising time can lead to the improvement of discharge uniformity and the discharge current.Therefore,a multi-parameter adjustable high-voltage nanoseconds pulse power was developed in this thesis.And an atmospheric needle to water discharge device was selected to conduct experiments in order to study the discharge characteristics and its application in sterilization.Firstly,a high-voltage solid state switch was made using 40 1200 V IGBT components in series connection.Based on two sets of high-voltage switch,a pulse power was made.During the experiments,photocoupler driving integrated circuit was used as the driver for IGBT.Besides,an electrical isolated power supply for the driver circuit was built.A driving signal transmission path using optical fiber was also built.During the test work,the falling time and rising time of the output pulse voltage at-5kV under the no-load condition are 45 ns and 52 ns,respectively.Secondly,the self-developed pulse power was used to excite a needle to water discharge device.The discharge morphology,discharge area and the optical emission spectrum characteristics were studied.The experiments showed that with the adding of voltage and pulse width,both discharge area and optical emission intensities of N₂（C）increased.And the comparison of using neutral aqueous solution,acid aqueous solution,alkaline aqueous solution and mental plane as the ground electrode showed that the discharge area and optical emission intensities of N₂（C）achieved their maximum value when using neutral aqueous solution.And the values achieved their minimum when using metal plane as the ground electrode.The total discharge intensities increased with the adding of gas flow rate.Different shape high-voltage electrodes led to different discharge morphology,but the total discharge intensities were almost the same.Finally,the self-developed pulse power was adopted to excite the discharge above the suspension containing Penicillium spores.The germination inhibition rate was used for the representation of sterilization effect.After the treatment of plasma,germination inhibition rate of spores increased when the applied pulse voltage and width was added.The germination inhibition rate also increased when the gas flow was added.And the sterilization effect was almost the same using different shape high-voltage electrodes.The sterilization effect was caused by a series of factors,containing the reactive species,charged particle,ultraviolet radiation,electric field and current.