How to Build a Magnetic Field Stronger Than a Star – Using a Laser

A powerful new technique harnesses swirling plasma inside laser-blasted microtubes to produce record-breaking magnetic fields—rivaling those near neutron stars—all within a compact laboratory setup.

This innovation promises to transform astrophysics, quantum research, and fusion energy experiments by unleashing megatesla-level forces using nothing more than targeted laser pulses and clever engineering.

Laser-Driven Breakthrough in Magnetic Field Generation

Researchers at The University of Osaka have developed a novel method for generating ultrahigh magnetic fields via laser-driven implosions of blade-structured microtubes. This method achieves field strengths approaching one megatesla—a breakthrough in compact, high-field plasma science.

Ultrastrong magnetic fields approaching the megatesla regime—comparable to those found near strongly magnetized neutron stars or astrophysical jets—have now been demonstrated in theory using a compact, laser-driven setup. A team led by Professor Masakatsu Murakami at The University of Osaka has proposed and simulated a unique scheme that uses micron-sized hollow cylinders with internal blades to achieve these field levels.

How Bladed Microtube Implosions Work

The technique—called bladed microtube implosion (BMI)—relies on directing ultra-intense, femtosecond laser pulses at a cylindrical target with sawtooth-like inner blades. These blades cause the imploding plasma to swirl asymmetrically, generating circulating currents near the center. The resulting loop current self-consistently produces an intense axial magnetic field exceeding 500 kilotesla, approaching the megatesla regime. No externally applied seed field is required.

This mechanism stands in stark contrast to traditional magnetic compression, which relies on amplifying an initial magnetic field. In BMI, the field is generated from scratch—driven purely by laser-plasma interactions. Moreover, as long as the target incorporates structures that break cylindrical symmetry, high magnetic fields can still be robustly generated. The process forms a feedback loop in which flows of charged particles—composed of ions and electrons—strengthen the magnetic field, which in turn confines those flows more tightly, further amplifying the field.

Bridging the Lab and the Cosmos

“This approach offers a powerful new way to create and study extreme magnetic fields in a compact format,” says Prof. Murakami. “It provides an experimental bridge between laboratory plasmas and the astrophysical universe.”

Potential applications include:

• Laboratory astrophysics: mimicking magnetized jets and stellar interiors
• Laser fusion: advancing proton-beam fast ignition schemes
• High-field QED: probing non-linear quantum phenomena

Simulations were conducted using the fully relativistic EPOCH code on the SQUID supercomputer at The University of Osaka. A supporting analytic model was also constructed to reveal the fundamental scaling laws and target optimization strategies.

Reference: “Gigagauss magnetic field generation by bladed microtube implosion” by D. Pan and M. Murakami, 14 July 2025, Physics of Plasmas.
DOI: 10.1063/5.0275006

Funding: Japan Society for the Promotion of Science (JSPS), Kansai Electric Power Company (KEPCO)

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