It is demonstrated experimentally that polydisperse Pd plasma of low energy (∼1 J) nanosecond vacuum discharge operating in a virtual cathode regime becomes an effective stochastic cavity in hard x-ray domain. A diffusion model of stochastic propagation of spontaneous x-ray radiation in the volume of randomly located reflecting clusters is developed also. The model provides qualitative explanation of both the experimentally observed effects of high-intensity bursts and partial ‘trapping’ of x-ray radiation. The x-ray burst emerges when photons are stored inside the plasma volume followed by instant release at the end of the discharge while the trapping regime corresponds to the slow developing x-ray diffusion with the characteristic time larger than the discharge duration. The results obtained are compared qualitatively with well-known concept of Letokhov’s random laser.

实验证明，在虚拟阴极状态下运行的低能（〜1 J）纳秒真空放电多分散Pd等离子体在硬X射线域成为有效的随机腔。还建立了自发X射线辐射在随机定位的反射团簇中随机传播的扩散模型。该模型对实验中观察到的高强度猝发效应和X射线辐射的部分“陷获”提供了定性解释。当光子存储在等离子体体积内部，然后在放电结束时立即释放时，X射线爆发出现，而捕获方式对应于缓慢发展的X射线扩散，其特征时间大于放电持续时间。