NIF is well known in the scientific community as the world’s largest laser, in terms of both size and energy. Occupying a space the size of a football stadium, this 192-beam ultraviolet laser system can generate 1.8 megajoules of energy focused on a target the size of a peppercorn. Such focused, intense energy generates the same temperatures, densities, and pressures found in the center of stars, planetary cores, and nuclear explosions. The science undertaken at NIF supports nuclear weapons stockpile stewardship, the quest to achieve nuclear fusion to ensure global energy security, and research in basic science such as nucleosynthesis, stellar physics, astrophysics, planetary physics, and plasma physics.
In pursuit of the latter goal, NIF opens its doors to researchers from around the world through its Discovery Science (DS) program. The program enables scientists from academic institutions and government laboratories to perform fundamental science experiments on a scale possible only on NIF. NIF runs experiments 24 hours a day, five days a week, and a portion of that time (8 percent) is dedicated to the Discovery Science program.
A Premier Facility for Fundamental Science
From the beginning, it was recognized that NIF would be able to make significant contributions to fundamental science, and that a portion of experimental time would be devoted to that effort. During the years between the dismantling of LLNL’s Nova laser, NIF’s predecessor, in 1999 and the opening of NIF in 2009, physicists from LLNL who needed the use of a powerful laser had to travel to the Laboratory for Laser Energetics (LLE) at the University of Rochester in New York to use LLE’s OMEGA laser. The working relationship that developed between the researchers of the two organizations proved mutually beneficial; in 2010, wishing to maintain contact with the academic world, LLNL launched a fundamental science research program that evolved into the Discovery Science program in 2014.
And in fact, academic collaborators have made significant contributions to NIF’s development. Richard Petrasso’s team at the Plasma Science and Fusion Center at the Massachusetts Institute of Technology (MIT), for example, helped develop a number of key diagnostics for NIF. (Diagnostics are the instruments or systems of instrumentation scientists use to measure experimental results.) Now NIF is conducting more than 400 shots a year, up from fewer than 200 in 2013, partly as a result of the creation of a wide selection of experimental platforms that can be customized to address the needs of individual experiments.
Benefits to LLNL
Making NIF available to outside researchers not only provides opportunities for advancing Discovery Science; it’s also advantageous for the facility’s primary mission of supporting stockpile stewardship. DS research serves as career development and an opportunity for innovative high energy density (HED) science for NIF scientists, who spend most of their time performing experiments in pursuit of long-range national security goals. By devoting a nominal portion of their time to DS projects, NIF scientists stay current on cutting-edge science and experimental techniques, which in turn keeps their thinking nimble and leads to the publication of results in high-impact journals.
In addition, NIF’s academic users are innovative thinkers and future leaders in the scientific community—just the sort of people with whom LLNL would wish to form lasting relationships. While wooing potential new hires into careers at the Laboratory—especially candidates who are much sought-after by prestigious academic institutions—LLNL benefits from its ability to offer continued access to leading-edge research. It’s worth noting that all of the LLNL scientists who assist DS users do so voluntarily.
“It’s good to have NIF open to the public for the future of the Lab,” says NIF Discovery Science Leader Bruce Remington. “Fusion is a relatively new field with enormous scientific challenges, as evidenced by fact that we haven’t achieved ignition yet.” It’s important, therefore, “to keep the best and brightest (young scientists) engaged with us.”
In the seven years since the inception of the fundamental science program, about ten scientists who brought projects to the program while in graduate school have been hired by Lawrence Livermore, Los Alamos, and Sandia national laboratories. That’s more than one hire per year, and clear evidence that the program provides, as Remington calls it, “a success path” between top academic institutions and the labs.
For example, Alex Zylstra, now a Los Alamos plasma and nuclear physicist, did his graduate work in Petrasso’s group at MIT, where he helped develop diagnostics for NIF. At the same time, he was doing his own fundamental research on charged-particle stopping power. His work led him first to experiments on the OMEGA laser and later to develop his own Discovery Science project.
“You’ve got to walk before you can run,” Zylstra says, but it was his familiarity with NIF that let him know that running was possible, and thus shaped the arc of his work. Zylstra went on to receive the Reines Fellowship and become a staff scientist at Los Alamos, for which he also does programmatic work at NIF.
Like many DS participants, Zylstra became a repeat user while still in graduate school, working on the DS projects of other people in his department and further cementing the ties that develop between NIF and top university physics programs.
The challenge, as Remington describes it, is to maintain those relationships without becoming insular. “Success for Discovery Science,” he says, “would mean a continued connection to MIT, the University of Oxford, UC Berkeley, the University of Michigan, and the University of Rochester—which are generating lots of prepared graduate students—but also the establishment of more relationships with top-tier feeder universities.” His goal is for a reasonable fraction of the Discovery Science teams each year to be new users, and he is actively cultivating relationships with universities in the United States and abroad in order to encourage that to happen.
The competition abroad is stiff, though. Following a model similar to the Discovery Science program, the British and French governments have also opened up their laser facilities to academics in order to engage in intellectual cross-pollination.
An Ideal Discovery Science Project
Discovery Science projects tend to have certain qualities is common. Of course, they must fall within NIF’s experimental capabilities, but beyond that, they also have high scientific impact and are exciting, creative, and complex, challenging NIF scientists to step up their game so they can stay fresh. A summary of recent experiments shows the breadth, depth, and cutting-edge nature of current DS research.
U.S. scientists at academic institutions, research laboratories, and small businesses, and overseas scientists at academic institutions and national laboratories, are all eligible to propose Discovery Science experiments at NIF. The one thing all DS users have in common is that they are doing high-impact research at the frontiers of science, answering universal questions within an active community. Many DS users are young scientists, often graduate students, who aspire to be leaders in their fields. Prior experience on OMEGA, LLNL’s Jupiter Laser System, or comparable facilities is a plus, as Zylstra’s experience demonstrates.
Encouraging New Users
Discovery Science PIs often become repeat users, but Remington, who is tasked with cultivating and maintaining relationships with academic institutions, admits that his biggest challenge by far is finding first-time users. “The most common response I get from graduate students whose work has Discovery Science potential is that ‘It appears too hard. It’s too complicated,’” he says. “They’re afraid they won’t be able to get on top if it.” His key message to potential users: “It’s not that complicated.”
Indeed, the inherent complexity of these projects is ameliorated by the people at NIF, who work hard to support the success of DS projects because they know that in doing so they are establishing relationships with tomorrow’s top scientists and possible future colleagues. That’s why NIF staff scientists, engineers, and technicians volunteer to assist the principal investigators (PIs) by providing iterative feedback as the project plan develops, a process that can take a year or more.
Proposing an Experiment
Proposing and developing a Discovery Science project follows a refined process modeled on the best practices of the scientific community; it’s similar to applying for a scientific award or a space mission with NASA. Would-be users begin by submitting a letter of interest, due in July. The letter is reviewed by Remington and the Feasibility Review Committee (FRC) to assess whether the project is currently achievable on NIF. They then respond to the PI with guidance for developing a formal proposal, which is due in September.
The FRC reviews the detailed proposals for feasibility, while the Technical Review Committee (TRC) performs a peer review. The TRC is an outside panel of technical experts composed of prominent scientists from institutions that have a history of conducting high energy density research on their own, such as the University of Rochester, Princeton University, Stanford University, the University of California, the University of Wisconsin, and others.
After the FRC and TRC have completed their respective reviews, PIs of promising projects are invited to give an oral presentation and participate in a Q&A session with the TRC via a Web conference. The TRC—not NIF—then ranks the proposals and submits this list as its input to the NIF director regarding which proposals should be accepted. Out of 26 proposals received this year, about six will be accepted for shot time in 2018-19.
The NIF User Office and NIF User Group
“The User Office is where the user meets the facility. It’s where users go to get a project ready for NIF,” says its director, Kevin Fournier. It is Fournier who acts as liaison between the users and the laser, diagnostics, and operations teams who will make the shot happen. It’s a job for which, as a plasma physicist and former program manager in charge of NIF National Security Applications projects, he is well suited.
The User Office coordinates the administrative aspects of the call for Discovery Science proposals and provides the technical personnel who serve on the FRC and the scientific personnel who serve as resources for successful Discovery Science teams to help the teams turn their ideas into NIF experiments. The User Office hosts a monthly forum for all users, interested researchers, program managers and department heads and works closely with the NIF User Group (NUG), for which Fournier is the in-house point of contact. “The User Office is there to help,” says Fournier, “so we value direct feedback from stakeholders.”
That feedback usually comes from the NUG, which is made up of representatives of the HED science community, including the PIs of NIF projects. Although he or she can opt out at will, every PI is automatically enrolled in the NUG as soon as a Discovery Science project is accepted. The NUG provides another layer of support for PIs and the opportunity to participate in the larger scientific community.
Don Lamb, Director of the Flash Center for Computational Science at the University of Chicago and Director of the NUG, explains: “More than 500 scientists around the world are members of the NUG. The NUG hosts a meeting each year that includes descriptions of NIF’s capabilities and talks by scientists about the results of their Discovery Science experiments and their plans for future experiments. The meeting is a wonderful place for young scientists to learn more about NIF and the cutting-edge experiments being done at it.”
Through the NUG, PIs help shape NIF processes and procedures. For example, the NUG successfully advocated for the use of Web conferencing for the oral presentations to the proposal committee in order to save PIs the time and expense of traveling to Livermore for a short proposal defense.
Once a proposal has been accepted, a focused period of project development begins. The NIF does not guide the project development or shape the project in any way, but rather provides iterative feedback on the project design to help ensure the best use of shot time. Every DS user can expect to engage with a number of NIF experts during this process—target fabrication experts, target alignment experts, and others. In a number of cases, however, NIF HED scientists are on the DS teams or are the DS PIs themselves, and in these cases, they help guide and formulate the science.
LLNL has developed a number of project platforms to accommodate the everyday work at NIF (see Experimental Capabilities). A platform is composed of the diagnostics, the laser, and the target. The diagnostic performance, the laser configuration, and the target parameters are precisely designed to work together to deliver the data that enable understanding of the physics under investigation.
Once a DS project has been accepted, the PI must determine which platform best suits the project, and then, because every project is unique, adjust it as needed.
Some potential users might find this process intimidating, but Zylstra says they shouldn’t. “I found people in this community to be very willing to help, and your liaison scientist can help you reach out to the appropriate person,” he says. After spending time at NIF, he understands why. “NIF has a friendly, collaborative culture that carries over into the Discovery Science program.”
Asked if he ever volunteers to assist new PIs with DS projects, he says with enthusiasm, “Of course!”
Why? “Because it’s fun.”