Collective processes in plasmas often induce microinstabilities that play an important role in many space or laboratory plasma environments. Particularly notable is the Weibel-type current filamentation instability, which is believed to drive the creation of collisionless shocks in weakly magnetized astrophysical plasmas. Here, this instability class is studied through interactions of ultraintense and short laser pulses with solid foils, leading to localized generation of megaelectronvolt electrons. Proton radiographic measurements of both low- and high-resistivity targets show two distinct, superimposed electromagnetic field patterns arising from the interpenetration of the megaelectronvolt electrons and the background plasma. Particle-in-cell simulations and theoretical estimates suggest that the collisionless Weibel instability building up in the dilute expanding plasmas formed at the target surfaces causes the observed azimuthally symmetric electromagnetic filaments. For a sufficiently high resistivity of the target foil, an additional resistive instability is triggered in the bulk target, giving rise to radially elongated filaments. The data reveal the growth of both filamentation instabilities over large temporal (tens of picoseconds) and spatial (hundreds of micrometres) scales.

血浆中的集体过程通常会诱发微不稳定性，这种微不稳定性在许多空间或实验室血浆环境中起着重要作用。尤其值得注意的是Weibel型电流丝不稳定性，据信这种不稳定性会导致在弱磁化的天体等离子体中产生无碰撞冲击。在这里，通过超强和短激光脉冲与固体箔的相互作用研究了这种不稳定性类别，从而导致了兆伏电子的局部生成。低电阻率目标和高电阻率目标的质子射线照相测量结果显示，由于兆伏电子和背景等离子体的互穿而产生的两种不同的叠加电磁场模式。单元中的粒子模拟和理论估计表明，在目标表面形成的稀膨胀等离子体中建立的无碰撞Weibel不稳定性会导致观察到的方位角对称电磁丝。对于靶箔的足够高的电阻率，在块状靶中引发了额外的电阻不稳定性，从而产生了径向伸长的细丝。数据揭示了在大的时间尺度（数十皮秒）和空间尺度（数百微米）上丝状失稳的增长。产生径向伸长的细丝。数据揭示了在大的时间尺度（数十皮秒）和空间尺度（数百微米）上丝状失稳的增长。产生径向伸长的细丝。数据揭示了在大的时间尺度（数十皮秒）和空间尺度（数百微米）上丝状失稳的增长。