Measuring magnetic fields in laser-driven coils with dual-axis proton deflectometry
Measuring magnetic fields in laser-driven coils with dual-axis proton deflectometry
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DOI：
10.1088/1361-6587/ac0bca
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发表时间：
2021-06
影响因子：
2.2
通讯作者：
P. Bradford;A. Dearling;M. Ehret;Luca Antonelli;Nicola Booth;David Carroll;Rob Clarke;Kevin Glize;Robert Heathcote;Matthew Khan;John Moody;S. Pikuz;Brad Pollock;Martin P Read;Sergey Ryazantsev;Christopher Spindloe;C. P. Ridgers;J. Santos;V. Tikhonchuk;N. Woolsey
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作者：
P. Bradford;A. Dearling;M. Ehret;Luca Antonelli;Nicola Booth;David Carroll;Rob Clarke;Kevin Glize;Robert Heathcote;Matthew Khan;John Moody;S. Pikuz;Brad Pollock;Martin P Read;Sergey Ryazantsev;Christopher Spindloe;C. P. Ridgers;J. Santos;V. Tikhonchuk;N. Woolsey
通过在两个金属板之间驱动热电子，高功率激光器可以在微型线圈靶中产生多特斯拉的准静态磁场。许多涉及激光线圈靶的实验依赖于垂直于线圈轴的质子偏转测量来提取磁场的测量值。在本文中，我们表明，使用垂直探测的定量测量是复杂的GV m−1电场的存在下，在亚纳秒的时间尺度上发展的目标。平行于线圈轴与基准网格的探测被证明是可靠的分离的电场和磁场测量，给出电流估计I 5 kA在1毫米和2毫米直径的线环。在电场和磁场中的质子偏转的分析模型被用来基准的粒子在细胞代码的结果，并帮助去卷积的磁场和电场偏转。结果被用来激励一个新的实验方案，结合了轴向质子探测和直流测量的单板目标。与传统的目标和诊断设置相比，该方案具有几个重要的优点，能够可靠地测量线圈磁场和等离子体特性，并且更容易在一系列激光强度下验证不同的理论模型。
By driving hot electrons between two metal plates connected by a wire loop, high power lasers can generate multi-tesla, quasi-static magnetic fields in miniature coil targets. Many experiments involving laser-coil targets rely on proton deflectometry directed perpendicular to the coil axis to extract a measurement of the magnetic field. In this paper, we show that quantitative measurements using perpendicular probing are complicated by the presence of GV m−1 electric fields in the target that develop on sub-ns timescales. Probing parallel to the coil axis with fiducial grids is shown to reliably separate the electric and magnetic field measurements, giving current estimates of I ≈ 5 kA in 1 mm- and 2 mm-diameter wire loops. An analytic model of proton deflection in electric and magnetic fields is used to benchmark results from the particle-in-cell code and help deconvolve the magnetic and electric field deflections. Results are used to motivate a new experimental scheme that combines a single-plate target with axial proton probing and direct current measurements. This scheme has several important advantages over the traditional target and diagnostic set-up, enabling the robust measurement of coil magnetic fields and plasma properties, as well as making it easier to validate different theoretical models at a range of laser intensities.