大功率高压电子加速器能量脉动测量

电子加速器能量脉动的大小是影响电子加速器稳定可靠运行的重要因素之一。利用R-C串联方法测量能量脉动的结果说明电子加速器的能量脉动测量存在磁场干扰。采用有限元法数值计算了电子加速器中高压发生器结构改动前后的磁场干扰值的大小,通过对高压发生器结构的改,最后测量到较真实的能量脉动系数。说明用这种高压发生器的三相电子加速器所产生的能量脉动系数可以满足电子加速器正常工作的要求,可以确定能量脉动系数太大不是加速器在强流工作时稳定性变差的主要原因。 he Ripple coefficient is one of the important factor for the stability of industrial high voltage electron accelerator. Accelerator can’t work well when the ripple coefficient is high. The increment of the measured ripple values becomes very large with the increase of the accelerator load current. From the simulation with finite element method of high voltage generator,we found that the leakage magnetic field was the most important reason for the results of ripple measurement. The ripple was measured after changing the frame of the high voltage generator to suppress the leakage magnetic field. It can be concluded that the actual value is acceptable to the accelerator and the measured high ripple coefficient is not the reason of malfunction of this high power electron accelerator.     

带有局部源的非局部扩散方程组的Fujita现象

本文研究了一类带有局部源的非局部扩散系统$u_t=J*u-u+a(x)v^{p}$, $v_t=J*v-v+a(x)u^q$的柯西问题,首先根据是否存在全局解建立了Fujita曲线$(pq)_c=1+\max \{p+1,q+1\}$,也即证明了:如果$1(pq)_c$时,则既存在全局解,也存在非全局解.然后我还根据初始值在无穷远处的衰减率建立了第二临界曲线.