Study On The Generation Of High Power Electromagnetic Pulses Based On Tesla Transformer

High power electromagnetic pulses (EMP) have a wide variety of applications including transient radar, concealed object detection, mine clearing, pipeline inspections, electronic effects testing and so on. Compared to traditional pulse power technique, the key of generating high power electromagnetic pulses lies in sub-nanosecond pulse conditioning and high repetition running. Under the aboved two directions, the theoretical study numerical simulation engineering design and experimental study involved in developing high power EMP generator will be demonstrated in the dissertation.From the angle of pulse power compression on timescale, the idea for developing high power EMP generator is proposed. Namely, primary pulse power source technique, Tesla transformer with pulse forming line incorporated technique, transmission line charging technique are adopted to realize the pulse width scaling from millisecond regime to microsecond regime then to nanosecond and eventually to sub-nanosecond regime respectively.Considering the generation of pulses on the microsecond regime, certain primary power sources reported by corresponding institutes are compared. On the basis of analysis, full wave rectified circuit is proposed to increase the available coefficient of electric supply and decrease the need for the turn ratio of Tesla transformer. The working process and engineering design guideline is illustrated in detail. A high power primary power source setup with pulse width 30μs, output voltage 550V, output current 11.5KA,and repetition rate 100Hz is developed.The model of Tesla transformer concerned the nanosecond pulse generation is thoroughly analyzed using complex frequence domain method. The analytic results show that the ideal Tesla transformer cannot be reached owing to the incapable of reverse current in the fast thysistor, which has be chosen in the primary power source. The parameters for nonideal Tesla transformer are decided by using the transient ciruit simulation method. A compact Tesla transformer and PFL with coupling coefficient 0.85, charged voltage 300KV, and output pulse width 3.6ns is developed.The traditional subnanosecond power conditioning technique is compared with the idea of transmission line charging. Based upon which, the new concepts of matched or mismatched transmission line charging are introduced and thus the two methods are united. To investigate mismatched transmission line charging technique, three low impendance transmission lines with length 30mm, 45mm, 60mm respectively are designed.The discharged process of low inpendance PFL to high impendance resistor through impendance transformer is analyzed by indroducing FDTD method. The result obtained by indroduced method shows a good agreement with that obtained by using commercial software. The result also shows that the power gain defined on low impendance PFL can be realized on high impendance load.In the high power EMP generator experimental setup, a high power pulse driving source with 27Ω. output impedance based on tesla transformer is utilized as charging source, the subnanosecond pulse conditioning and radiating is realized by using transmission line charging technology and double ridged horn connected with impedance transformer respectively. High power electromagnetic pulses with pulse repetition frequency (PRF) reached 100Hz and maximum field-range product equal to 294KV can be achieved by the setup. The experimental results agree well with theoretic analysis and simulation results.To investigate the generation of multi-pulses in burst mode. A novel topology to realize high power electromagnetic multi-pulses in burst mode is proposed in the dissertation. Only one pulse power driving source based on tesla transformer is adopted in the setup, the multi-transmission lines are charged in parallel and discharged in series owing to electric isolation of air core inductance, which thus results in multi-pulses output. The experimental results show that the developed high power multi-pulses generator can operate in burst mode at 100pps, the output multi-pulses with pulsewidth about 40ns, energy spectral density is concentrated between 300MHz and 600MHz , the equivalent radiation power(ERP) is up to 100MW.Aiming at the random timing jitter periodical electromagnetic pulses radiated by practical electromagnetic pulse transmitter, a new way based on the analysis of the power spectral density(PSD) of timing jitter periodical 8-functions ,to derive the PSD of arbitrary timing jitter periodical electromagnetic pulses was proposed. The results show that the PSD of the concerned electromagnetic pulses constituted by discrete PSD and continuous PSD. The total power of the two parts is conservative. The numerical results demonstrate that the more timing jitter the less discrete PSD.