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Sustaining hundred‑tesla magnetic fields for nanoseconds in laser‑driven nanowire plasmas

Determine the physical mechanism that sustains magnetic fields of several hundred tesla over nanosecond durations in plasmas produced by relativistic femtosecond laser interaction with Si‑core/TiO2‑clad nanowire arrays, sufficient to confine hot (0.4–1.2 keV), dense (5×10^20–10^22 cm^−3) Ti plasma jets observed via He‑like Ti20+ emission extending up to ~1 mm from the target surface.

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Background

Spatially resolved X‑ray spectroscopy revealed jet‑like emission of He‑like Ti20+ extending up to ~1 mm from nanowire array targets, implying the presence of keV‑temperature, high‑density plasma persisting on nanosecond timescales.

PIC simulations predict kiloTesla‑scale magnetic fields forming within sub‑picoseconds in the nanowire arrays. A pressure‑balance estimate indicates that 200–600 T fields are required to confine the inferred jet plasma parameters over nanoseconds, but the mechanism that maintains such field strengths on these timescales is not established.

References

However, the question of how such strong magnetic fields can be maintained on nanosecond time scale remains open.

— Long Living Hot and Dense Plasma from Relativistic Laser-Nanowire Array Interaction (2510.09437 - Eftekhari-Zadeh et al., 10 Oct 2025) in Section 4 (Numerical simulations), discussion around Fig. 10