Berkeley Lab

Jens Osterhoff Joins BELLA Center, Strengthening Berkeley Lab Leadership in Plasma Accelerators

Jens Osterhoff, a researcher internationally recognized for his contributions to accelerator, laser, plasma, and beam physics, has joined the leadership team of the Accelerator Technology & Applied Physics (ATAP) Division’s BELLA Center as deputy director for projects and applications.

Jens Osterhoff, senior scientist and deputy director for projects and applications at ATAP’s BELLA Center. (Credit: DESY)

By Carl A. Williams, February 22, 2024

Osterhoff’s research focuses on beam-plasma interactions. He has played a pivotal role in advancing next-generation compact particle accelerators and high-energy particle colliders that use the revolutionary technology of plasma acceleration. Previously, he headed the Plasma Accelerator Department in the Accelerator Division at the Deutsches Elektronen-Synchrotron (DESY) in Hamburg, Germany. While at DESY, Osterhoff was the first researcher to work on plasma-based acceleration, established the Plasma Wakefield Accelerator Group, and conceived and led the FLASHForward plasma wakefield accelerator facility. Today, this group is amongst the largest in the world (similar in size to the team at Berkeley Lab) and focuses on laser- and beam-driven experimental concepts and theory. In 2021, he was awarded the Bjørn H. Wiik Prize—the highest scientific prize at DESY—for originating research on plasma acceleration and establishing a center of excellence in the area.

In addition to his outstanding research record on plasma acceleration, Osterhoff has leadership roles in a wide range of accelerator science, including the CERN Super Proton Synchrotron scientific advisory committee and the panel for Advanced and Novel Accelerators of the International Committee for Future Accelerators. Previously, he sat on the expert panel for High Gradient Acceleration-Plasmas and Lasers in the CERN Laboratory Directors Group and the EuPRAXIA Collaboration Board, the governing body of the EuPRAXIA Consortium. He also led the Compact Sources work package in the League of European Accelerator-based Photon Sources and was deputy spokesperson for the Accelerator Research and Development in the Matter and Technologies program of the Helmholtz Association.

“We are excited to have Jens join the leadership team,” said ATAP Division Director Cameron Geddes. “He brings a wealth of experience in particle acceleration and plasmas that will advance the division’s capabilities. In particular, his expertise will advance our proposed kBELLA facility, pushing the limits of ultrafast lasers as an enabling technology for laser-plasma accelerators for future colliders and high-impact applications in discovery science, medicine, and industry.”

In recent years, research on plasma acceleration has grown tremendously because of the enormous electric fields the plasma produces—hundreds to thousands of times that of conventional radio-frequency accelerators—that can accelerate particles much more rapidly than traditional methods. Furthermore, the ultra-high power lasers that drive plasma accelerators at labs such as BELLA and others worldwide are quickly evolving. (The inventors of this laser technology were awarded the 2018 Nobel Prize in Physics.)

Moreover, recent advances in laser technology and plasma science promise next-generation laser-plasma accelerators (LPAs) that are more compact and less expensive to build and operate than current machines. They could have applications in basic science, security, and industry, including small-scale medical accelerators for cancer therapy, mid-scale light sources for material science, and large-scale colliders for fundamental high-energy physics.

Advancing BELLA’s capabilities

Osterhoff received his doctorate from the Ludwig-Maximilians-Universität München in Germany in 2009. His doctoral research—under Ferenc Krausz, jointly awarded the 2023 Nobel Prize in Physics—explored ultra-relativistic electron beams produced by laser-wakefield acceleration. He has conducted postdoctoral research at the Munich-Centre for Advanced Photonics, the Max-Planck-Institut für Quantenoptik in München, and here at the Accelerator & Fusion Research Division (now ATAP), where he worked with colleagues at the Lab on the staging of laser-driven wakefield accelerator modules toward future colliders.

“It’s great to be back at Berkeley Lab and part of an excellent leadership team at BELLA,” said Osterhoff. “The center has grown tremendously over the years, and it’s very exciting to be involved in helping to drive our vision of building the next generation of accelerators and colliders through initiatives like kBELLA.”

“kBELLA is one of the most exciting projects planned in our field and promises to be a transformative project that uses efficient kilohertz drivers such as fibers—a new kind of laser driver for particle acceleration—that have the potential to revolutionize how we use plasma accelerators because of the higher average power, higher repetition rates, and increased robustness for user operations. I will focus on making the kBELLA project a reality while helping the established leadership at BELLA by providing additional perspectives.”

Jeroen van Tilborg (left), staff scientist and deputy director for experiments at BELLA, and Jens Osterhoff, senior scientist and deputy director for projects and applications, brainstorm over plasma accelerator development in the fiber laser R&D lab at Berkeley Lab. (Credit: Fanting Kong/Berkeley Lab)

According to Eric Esarey, director of BELLA, the kBELLA facility will address the two main issues limiting the application of laser-plasma accelerators: repetition rate and stability.

“Jens’ expertise and leadership will help us achieve our long-sought goal of bringing laser-plasma accelerators to real-world applications,” he said. “The lasers used to drive plasma accelerators are limited to a few hertz (Hz), whereas most applications require much higher repetition rates of a kHz and beyond.”

“In addition,” he continued, “the electron beams produced by the majority of the laser-plasma experiments to date exhibit large fluctuations in the beam properties, again greatly impeding their use in applications. The high repetition rates used in kBELLA will enable feedback and machine learning techniques to greatly improve beam stability and repeatability, which is essential for real-world applications.”

A pioneer in plasma acceleration

Osterhoff has a successful track record in leading the development of advanced accelerator technologies. For example, at DESY, he led the development of FLASHForward. This pioneering beam-driven research facility uses intense electron beams to drive the plasma accelerator; the same method is employed at the FACET-II facility at SLAC National Accelerator Laboratory.

While FLASHForward uses a different approach at BELLA, these approaches are complementary, with both facilities using intense beams to drive plasma accelerators (electron beams at FLASHFoward and laser beams at BELLA). Over the years, FLASHForward has produced a wealth of data and high-profile publications, significantly deepening the international community’s understanding of plasma acceleration.

However, Osterhoff says there is a gap between the promise of plasma accelerators and their application for the benefit of science and society.

“One of the key reasons this hasn’t happened yet is that the laser-plasma accelerators are still research machines, so they need a postdoc and Ph.D. student to operate them. This is not a solution if we want to use them for colliders or imaging applications in hospitals for diagnostics or cancer therapy, where they could save lives. You need a system that doesn’t need to be staffed by accelerator physicists, and is robust, scalable, and affordable.”

“My goal,” he continued, “is to help support the launch of kBELLA for the benefit of particle physics and, simultaneously, deliver this powerful, compact technology for many near-term applications.”

Plasma accelerators for high-energy physics

For the high-energy physics mission vital to BELLA, ATAP, and Berkeley Labs’ Physics Division, kBELLA is an essential step on the R&D path to realizing a plasma-based high-energy particle collider. For instance, the fiber lasers underlying kBELLA are one of the few laser technologies capable of scaling to the high repetition rates and efficiencies required by a collider. Recent advances in fiber technology achieved by the team led by ATAP scientists and their colleagues from Berkley Lab and the University of Michigan have rapidly closed the technology gap needed for kBELLA.

Given the vigorous worldwide research on lasers and plasma accelerators, noted Esarey, maintaining the Lab’s leadership “requires further investment in the U.S. program and facilities like kBELLA.”

“Jens joining us now is great timing and an important and crucial time, not just for kBELLA, but for the entire plasma accelerator community,” he added. “In light of the recommendations made in the recently released P5 report, he will help us deliver on the P5 recommendations and help Berkeley Lab lead the way on plasma accelerators, with the BELLA Center at the focus of laser-plasma accelerator research.”

Released in November, the 2023 Particle Physics Project Prioritization Panel (P5) Report outlines recommendations for the US particle and high energy physics program over the next decade. It includes strong support for expanded programs on general accelerator R&D and future collider studies. The report recommends enhancing the nation’s beam test facilities, including upgrades such as kBELLA, initializing a new program for design studies of future colliders at the 10 TeV per parton physics frontier, and highlights the development of laser-plasma wakefield accelerators as one of the possible paths to a 10 TeV collider. Jens will have leadership roles in these areas, in particular, on kBELLA, which is a critical technology demonstrator for a future plasma-based collider, and on design studies of a plasma collider at 10 TeV, which could use fiber technology scaled up in repetition rate and energy from that proposed for kBELLA.


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