论文标题
相对论冲击前体中血浆空化不稳定性的磁场扩增
Magnetic field amplification by a plasma cavitation instability in relativistic shock precursors
论文作者
论文摘要
等离子体流的不稳定性在相对论冲击及其环境中在磁场扩增和颗粒加速度中起重要作用。但是，在远距离的冲击前体区域，加速颗粒构成高度相对论和稀释的光束，与梁颗粒的gyroradii相比，流态不稳定性通常会变得效率低下，并且在很小的尺度上工作。我们报告了血浆空化不稳定性，该血浆不稳定性是由稀释的相对论梁驱动的，并且可以通过数量级来增加磁场强度和相干性尺度，以达到与梁能量密度的接近设备值。这种不稳定性在开发芯片不稳定性后增长，并与背景lept子和离子对梁电流的不对称响应有关。所得的净电感电场驱动了积极和带负电荷的光束物种之间的强能不对称性。大规模粒子中的粒子模拟用于验证不稳定性的生长和饱和水平的分析预测，并表明它在各种条件下（包括与配对等离子体相关的条件）具有鲁棒性。这些结果可能对伽马射线爆发中的冲击的磁化和结构具有重要意义，更普遍地对等离子体天体物理环境中相对论充电颗粒的磁场扩增和不对称散射。
Plasma streaming instabilities play an important role in magnetic field amplification and particle acceleration in relativistic shocks and their environments. However, in the far shock precursor region where accelerated particles constitute a highly relativistic and dilute beam, streaming instabilities typically become inefficient and operate at very small scales when compared to the gyroradii of the beam particles. We report on a plasma cavitation instability that is driven by dilute relativistic beams and can increase both the magnetic field strength and coherence scale by orders of magnitude to reach near-equipartition values with the beam energy density. This instability grows after the development of the Weibel instability and is associated with the asymmetric response of background leptons and ions to the beam current. The resulting net inductive electric field drives a strong energy asymmetry between positively and negatively charged beam species. Large-scale particle-in-cell simulations are used to verify analytical predictions for the growth and saturation level of the instability and indicate that it is robust over a wide range of conditions, including those associated with pair-loaded plasmas. These results can have important implications for the magnetization and structure of shocks in gamma-ray bursts, and more generally for magnetic field amplification and asymmetric scattering of relativistic charged particles in plasma astrophysical environments.
