Experimental Observation of a Current-Driven Instability in a Neutral Electron-Positron Beam

J. Warwick, T. Dzelzainis, M. E. Dieckmann, W. Schumaker, Domenico Doria, Lorenzo Romagnani, K. Poder, J. Cole, A. Alejo, M. Yeung, K. Krushelnick, S.P.D. Mangles, Z. Najmudin, B. Reville, G. M. Marrero Samarin, D. D. Symes, A.G.R. Thomas, M. Borghesi, G. Sarri

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We report on the first experimental observation of a current-driven instability developing in a quasineutral matter-antimatter beam. Strong magnetic fields (≥ 1 T) are measured, via means of a proton radiography technique, after the propagation of a neutral electron-positron beam through a background  electron-ion plasma. The experimentally determined equipartition parameter of ϵB ≈ 10−3 is typical of
values inferred from models of astrophysical gamma-ray bursts, in which the relativistic flows are also expected to be pair dominated. The data, supported by particle-in-cell simulations and simple analytical estimates, indicate that these magnetic fields persist in the background plasma for thousands of inverse plasma frequencies. The existence of such long-lived magnetic fields can be related to analog astrophysical systems, such as those prevalent in lepton-dominated jets.
Original languageEnglish
Article number185002
Number of pages5
JournalPhysical Review Letters
Publication statusPublished - 03 Nov 2017


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