Different schemes to produce ultrahigh magnetic fields are discussed. “Microtube implosion” [1-3] is a novel scheme to generate ultrahigh magnetic fields of the megatesla order. The microtube implosion is driven by ultraintense and ultrashort laser pulses. In the original concept of the microtube, however, uniform magnetic fields of the kilotesla order must be pre-seeded along the microtube axis to induce Larmor gyromotion of the imploding ions and electrons. Recently we have found that a structured microtube target can also generate ultrahigh magnetic fields even without seeded magnetic fields. In this case, due to the specific structure made on the inner surface of the microtube, vortex flows of relativistic electrons are collectively formed around the center of the cylindrical target to induce ultrahigh spin current. Two- and three-dimensional particle simulations are performed to clarify the underlying physics of the generation of ultrahigh magnetic fields using the vortex-driven microtube implosions. In addition, we show another type of laser-driven target, “Paisley target”[4], which can produce sub-megatesla magnetic fields without seed magnetic fields.

 

[1] M. Murakami, J.J. Honrubia, K. Weichman et al., Sci. Rep. 10, 16653 (2020).

[2] Y. Gu and M. Murakami, Sci. Rep. 11, 23592 (2021).

[3] D. Shokov and M. Murakami, High Power Laser Sci. Eng. 9, e56 (2021).

[4] Appl. Phys. Lett. 120, 132403 (2022).