Measuring magnetic fields in laser-driven coils with dual-axis proton deflectometry
| Autor: | Christopher Ridgers, Joao Santos, Philip Bradford, Nicola Booth, Adam Dearling, B. B. Pollock, M. Ehret, Robert Clarke, S. A. Pikuz, John Moody, Christopher Spindloe, Kevin Glize, Nigel Woolsey, David Carroll, Robert Heathcote, Martin Read, Vladimir Tikhonchuk, Luca Antonelli, S. N. Ryazantsev, Matthew Khan |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Plasma Physics and Controlled Fusion. 63:084008 |
| ISSN: | 1361-6587 0741-3335 |
| DOI: | 10.1088/1361-6587/ac0bca |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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