分析了激励脉冲电压作用下铁电阴极电容的变化，即等离子体沿着铁电阴极前电极表面扩散而引起电容变化；建立了激励脉冲电压作用下铁电阴极等效电容模型并推导铁电阴极前电极表面等离子横向扩散速度表达式。采用传统固相烧结工艺制备的掺镧锆锡钛酸铅反铁电陶瓷作为阴极材料，通过测量激励脉冲电压作用下铁电阴极两端的电压及充放电电流，计算得到掺镧锆锡钛酸铅陶瓷表面等离子体横向扩散速度为1.89×106 cm/s。

The changes of the capacitance of ferroelectric cathode under high trigger voltage are analyzed. The change is the plasma diffusion along the surface of top electrode under high trigger voltage. The model of the equivalent capacitance of ferroelectric cathode is established. And on this basis, the equation of the lateral velocity of the plasma diffusion is derived. An antiferroelectric cathode material, lanthanum-doped lead zirconate stannate titanate is prepared by using the method of solid-state calcinations. The lateral velocity of the plasma diffusion is calculated by measuring the voltage and charge-recharge current of ferroelectric cathode under trigger voltage of La-doped Pb(Zr,Sn,Ti)O3 ferroelectric cathode. The result is about 1.89×106cm/s.