Research On The ICF Electromagnetic Pulse Radiation Diagnosis And Shielding Design

To explore controlled thermonuclear new energy and address the increasingly severe energy chal enge,Inertial Confinement Fusion(ICF)has become one of the most active cutting-edge research fields in contemporary physics in recent years.Besides,it also plays a vital role in military use since the highly dense energy state in the ICF process meets the requirement of nuclear weapon applications.To realize the inertial confinement fusion,nanosecond or even picosecond pulse laser is used to interact with the target.However,the intense electromagnetic pulses irradiated in ICF not only affect the accuracy of the experiment data acquisition but could also cause damage to the precise diagnost ic equipment.Carrying out the diagnosis and shielding of the electromagnetic pulse signal under laser shooting circumstance is thus urgently needed.Based on the research subject of the ICF Electromagnetic Pulse radiation diagnosis and its shielding design,this dissertation systematically measures the electromagne t ic pulse signals irradiated from the interaction between laser and the target in ShenGuang ?laser facility by using various self-designed pulse antennas,including magnetic field antennas: B-dot antennas,tube antennas;electricfield antennas: discone antennas,square planar monopole antennas,UWB microstrip antennas.The initial EMP peak voltage inside and outside the target chamber reaches 1350 V and 4 V respectively.Based on the diagnosis results of ShenGuang?laser facility,the influences of target geometries on EMP signals are analyzed and the result indicates the symmetric target structure is beneficial to mitigate electromagnetic radiation.The experimental results also reveal that,to a certain extent,backward-wave oscillation inside and outside the target chamber increases EMP amplitude and extends the duration of the signal.Series of EMP investigative mechanism experiments are conducted on the hundred joules laser facilit y,the result identifies that the dipole radiation of target pole current is as one of the mechanisms for nanosecond laser to induce EMP signal when coupling with the target material.Besides,it also shows that backward-wave oscillation is one of the important sources to generate electromagnetic pulse.Using absorbing pyramid materials as the main raw material for electromagnetic shielding design,electromagnetic pulse shielding can and anechoic chamber are successfully developed and the calibration results show that they give good electromagnetic shielding performance.Coaxial cables are calibrated to reduce the systemic error.It is found that different types of cable affect the signal transmission differently,the amplitudes of the time domain and frequency domain electromagnetic pulse signal present significant attenuation as cable length increases.The measurement of electromagnetic pulses generated from laser shooting,conducted in this dissertation,has high reference value for the evaluation of electromagnetic interference of ShenGuang series facilities.Relevant electromagne t ic shielding design work is then carried out,making contribution to the precision improvement of diagnostic equipment being used in ICF experiments and the successful application of equipment electromagnetic protection.This dissertation provides auxiliar y basis for the successful implementation of related fusion diagnosis techniques.