Researchers from Osaka University, Japan, have discovered a novel mechanism, called ‘microtube implosion’, which demonstrates the generation of megatesla order magnetic fields.
Since the 19th century, researchers have struggled to create strong magnetic fields in laboratories for fundamental studies and diverse applications. Magnetic tomography, used in hospitals, is about 1 tesla (104 G). By contrast, future magnetic fusion and maglev trains will require magnetic fields on the megatesla (10,000,000,000 G) and kilotesla (10,000,000 G) order. To date, the highest magnetic fields experimentally observe are on the kilotesla order.
The researchers at Osaka University demonstrated that microtube implosion generates megatesla order magnetic fields. By conducting particle simulations using a supercomputer, the team produced three orders of a magnitude higher than what has ever been achieved in a laboratory before. Such high magnetic fields are expected only in celestial bodies like neutron stars and black holes.
Research lead, Professor Masakatsu Murakami of the Institute of Laser Engineering, Osaka University, wrote in a new paper, published in Nature: ‘We propose a novel concept called microtube implosion, which produces megatesla order magnetic fields using intense laser pulses. Key physical elements of microtube implosion are imploding ion fluxes with quasi-relativistic speeds and the resultant ultrahigh spin currents running around the nanometer-scale Larmor hole at the centre’.
The team used ultra-intense laser pulses to irradiate a plastic microtube one-tenth the thickness of a human hair, producing hot electrons with temperatures of billions of degrees. These hot electrons, along with cold ions, expand into the microtube cavity at velocities approaching the speed of light.
Pre-seeding with a kilotesla order magnetic field causes the imploding charged particles to become infinitesimally twisted due to Lorenz force. Such a unique cylindrical flow collectively produces unprecedented high spin currents of about 1015 ampere/cm2 on the target axis and consequently, generates ultrahigh magnetic fields on the megatesla order.
Murakami’s team has confirmed that current laser technology can realise megatesla order magnetic fields based on the concept. The present concept for generating megatesla order magnetic fields will lead to pioneering fundamental research in numerous areas, including materials science, quantum electrodynamics, and astrophysics, as well as other cutting-edge practical applications.