The laser that will be the most powerful in the United States is about to send its first pulses into an experimental target at the University of Michigan.
Funded by the National Science Foundation, it will be a destination for researchers studying extreme plasmas in the United States and around the world.
Called ZEUS, the Zetawatt equivalent ultrashort pulse laser system, it will explore the physics of the quantum universe as well as outer space, and it is expected to contribute to new technologies in medicine, electronics and national security.
“ZEUS will be the highest peak power laser in the United States and among the most powerful laser systems in the world. We look forward to growing the research community and bringing people together with new ideas for experiments and applications,” said Karl Krushelnick, director of the Center for Ultrafast Optical Science, home of ZEUS, and the Henry J. Gomberg Collegiate Professor of Engineering. .
The first target zone to turn on is the high-repetition target zone, which runs experiments with more frequent but lower power laser pulses. Michigan alumnus Franklin Dollar, associate professor of physics and astronomy at the University of California, Irvine, is the first user, and his team is exploring a new kind of X-ray imaging.
They will use ZEUS to fire infrared laser pulses into a helium gas target, turning it into plasma. This plasma accelerates electrons to high energies, and these electron beams then squirm to produce tightly packed X-ray pulses.
Dollar’s team is studying how to make and use these new types of X-ray sources. Because soft tissues absorb X-rays at very similar rates, basic medical X-ray machines must deliver high doses of radiation before they can be able to distinguish between a tumor and healthy tissue, he said.
But during his doctoral studies under Krushelnick, Dollar used the ZEUS predecessor to image a damsel, showing the promise of laser-like X-ray pulses. Different soft tissues in the damselfish carapace delayed the x-rays to varying degrees, creating interference patterns in the x-ray waves. These patterns revealed the soft structures with very short x-ray pulses – a few millionths billionths of a second – and therefore small doses of X-rays.
“We could see every little organ as well as the tiny micro hairs on his leg,” Dollar said. “It’s very exciting to think about how we could use these laser-like X-rays to do low-dose imaging, taking advantage of the fact that they’re laser-like rather than having to rely on the absorption imagery of the past.”
In this first phase, the ZEUS team starts at a power of 30 terawatts (30 trillion watts), or about 3% of the most powerful lasers in the United States today and 1% of the eventual maximum power of ZEUS.
“During the experiment here, we’re going to bring the first light into the target chamber and expand toward that 300 terawatt level,” said electrical and computer engineering researcher John Nees.
Nees is leading the construction of the laser alongside Anatoly Maksimchuk, an electrical and computer engineering researcher, who is leading the development of the experimental areas.
Dollar’s team plans to return in late fall for another run, aiming for full power aimed at the high-repeat, 500 terawatt target zone. The maximum power of 3 petawatts, or quadrillion watts, will go to different target areas to be completed later. The first test using the target area for the ZEUS signature experiment is scheduled for 2023.
This experiment will use the laser to generate a high-speed beam of electrons, then direct the electrons directly into the laser pulses. For electrons, this simulates a zetawatt laser pulse, a million times more powerful than ZEUS’ 3 petawatts. In addition to probing the foundations of our understanding of the quantum universe, ZEUS will allow researchers to study what happens inside some of the most extreme objects in space.
“Magnetars, which are neutron stars surrounded by extremely strong magnetic fields, and objects such as active galactic nuclei surrounded by very hot plasma, we can recreate the microphysics of hot plasma in extremely strong fields in the laboratory,” said said Louise Willingale, Associate Director. of ZEUS and Associate Professor of Electrical and Computer Engineering.
ZEUS not only provides scientific and technological opportunities, but with the discipline-wide effort to develop the laser physics workforce, it also creates career opportunities. Dollar brought his entire team to get the hands-on experience of commissioning experience on a world-class laser.
“At Michigan Engineering, we are blessed with some of the strongest academic and research capabilities in the world, and we leverage that strength to improve the lives of real people. ZEUS exemplifies our commitment to basic science – using engineering to understand matter at its most basic levels, then using that knowledge to create solutions to real-world problems,” said Alec D. Gallimore, Dean of Robert J. Vlasic Engineering.
The first stage of the experiment looks particularly tough to win due to how the pandemic disrupted construction early on, when the team was still reconfiguring the building to accommodate a much larger laser. Project manager Franko Bayer reconsidered the schedules, identifying work that could be done in parallel rather than in sequence, to stay as close to the original deadlines as possible.
“Our team at ZEUS is very pleased that our hard work has paid off, and despite all the post-pandemic equipment delivery delays, we are on schedule against our original schedule. This experience is the start of a gradual increase in power until full commissioning in the fall of 2023,” Bayer said.
Krushelnick is also a professor of nuclear engineering and radiological sciences and of electrical and computer engineering. Gallimore is also the Richard F. and Eleanor A. Towner Professor of Engineering, Arthur F. Thurnau Professor, and Professor of Aerospace Engineering.