We use the qualitative, simplified modeling, and approximately self-consistent nonlinear-optical approaches to explain the nature of the regime under which relativistically intense laser pulses propagate in a plasma to distances exceeding the Rayleigh length considerably, as was found earlier by numerical simulation. Such a regime requires certain matching of the size of the laser spot with the plasma density and the laser pulse intensity. It corresponds to the so-called self-trapping of radiation, which has been well known since the 1960s for the quadratic nonlinearity of the medium’s dielectric permittivity and, as has been established, takes place for the relativistic plasma nonlinearity as well. The case of the plasma with a near-critical density is considered as it is of greatest interest in the context of practical applications. Synchronization of chaotic motions of the electrons accelerated by the laser pulse in the self-trapping regime is discussed.

我们使用定性的、简化的建模和近似自洽的非线性光学方法来解释相对论强激光脉冲在等离子体中传播到远远超过瑞利长度的距离的机制的性质，正如之前通过数值模拟发现的那样。这种制度要求激光光斑的大小与等离子体密度和激光脉冲强度有一定的匹配。它对应于所谓的辐射自陷，自 1960 年代以来，它因介质介电常数的二次非线性而广为人知，并且如已确定的那样，也发生在相对论等离子体非线性中。具有近临界密度的等离子体的情况被认为是在实际应用中最受关注的情况。