LIVERMORE, Calif. -- Pity the fusion scientists. Toiling at the National Ignition Facility, a $3.5 billion lab nestled here among vineyards an hour east of San Francisco, they were chagrined when they failed to ignite nuclear fusion by their September deadline last year.

Facing public scrutiny, President Obama proposed a 13.8 percent cut for the program in his 2014 budget request, bringing funding down to $401 million, and researchers diverted their attention away from energy and toward experiments focusing on nuclear stockpile stewardship.

Now, following a summer of increasingly promising results, there are rumblings that scientists have recently achieved a new milestone for fusion energy. It is not quite ignition, which is the hoped-for goal of releasing more energy than the amount used in triggering the reaction, but it's an important step in that direction.

However, they can't talk about it.

With the government shut down, America's 60-year-old experiment in high-energy physics has collided with its 230-year-old experiment in representative democracy. Though the national labs have enough cash to coast for a few weeks, institutions like Lawrence Livermore National Laboratory, home to the ignition facility, are trimming expenses where they can until a funding resolution passes Congress.

So the experiments can go on, but researchers can't officially say anything, according to a spokeswoman for Lawrence Livermore.

This is especially frustrating for fusion scientists, who believe they are on the cusp of what may be humanity's crowning achievement in energy: harnessing the reaction that powers the sun to produce gobs of clean electricity, drawing on a fuel source that covers two-thirds of the planet, granting energy security and solving climate change.

Death by a thousand budget cuts?
In theory, a fusion generator produces no carbon dioxide emissions, carries no risk of nuclear weapons proliferation, generates part of its own fuel and operates more safely than just about any other power source. And although fusion experiments have a long list of missed deadlines and shifted goalposts, scientists insist that practical fusion is no longer a mirage receding into the distance.

It promises an oasis from our energy problems, and this time, scientists think it may not be a mirage.

"Now is not the time to pull back from exploiting that performance and getting it over that final hurdle," said Mike Dunne, director of laser fusion energy at NIF. "If we pulled back now, we would be doing society a huge disservice."

Nuclear fusion is almost the inverse of nuclear fission, the process that drives conventional nuclear reactors. Rather than splitting a large atom like uranium apart, fusion releases nuclear energy by sticking small atoms, like hydrogen, together. But it's an extraordinarily complicated challenge, one that is just a decade away and always will be, according to a running joke scientists here have grown weary of hearing.

However, in an age of austerity, policymakers have to set priorities, and betting on something that only works in theory is a tough sell, especially when the gears of government are stuck in neutral.

While critics point to fusion's broken promises, defenders note that these projects have suffered budgetary chips and gashes since their inception, leading progress to stutter and stall. "These programs show decades and decades of research. At the same time, we've never really made the investments," said Andrew Holland, senior fellow for energy and climate at the American Security Project, a nonpartisan national-security think tank. "It's really a litany of programs canceled and commitments not met."

Right now, there are two main federally funded paths to fusion: inertial fusion, like the experiments at NIF, and magnetic confinement fusion, which uses powerful magnets to contain the reaction inside a doughnut-shaped vessel called a tokamak.

The tokamaks operate under the Department of Energy's Office of Science and cost just under $400 million to run annually. Several of these projects, like the Massachusetts Institute of Technology's Alcator C-MOD, are offline due to earlier budget cuts.

NIF, on the other hand, is under the umbrella of the National Nuclear Security Administration. Since part of its mission is to provide research and guidance to maintain America's thermonuclear stockpile, the facility has steadier support.

The United States is also on the hook for 9.1 percent of expenses in the International Thermonuclear Experimental Reactor, a $20 billion global magnetic fusion project under construction in Cadarache, France.

'Cutting edge' science running on fumes
Because the French experiment is behind schedule and over budget, the Senate Energy and Natural Resources Committee sent a letter to the Government Accountability Office in May asking for an investigation into the United States' contributions to the project, concerned that ITER is cannibalizing resources from America's own tokamaks.

In addition, the country's on-again, off-again relationship with fusion is eroding the knowledge base for this work and turning off a generation of researchers. "This drip, drip, drip is no way to bring new scientists into the program," Holland said.

The current government crisis is creating anxiety among fusion scientists, as well. Since private contractors run most of the national labs, their workers aren't technically federal employees, so they aren't covered under the House's recently passed H.R. 3223, the "Federal Employee Retroactive Pay Fairness Act."

Last week, Rep. Eric Swalwell (D-Calif.), whose district includes Lawrence Livermore and the California campus of Sandia National Laboratories, sent a letter to Energy Secretary Ernest Moniz asking for lab employees to receive back pay should the government shutdown outlast than their cash reserves.

California Reps. Anna Eshoo, Barbara Lee and Zoe Lofgren co-signed the letter. "We take pride in the cutting edge advancements in our scientific research, but budget cuts and now a government shutdown are threatening these important undertakings," said Lofgren in a press release.

Given the potential and demand for fusion research, scientists say now is the time to step on the gas for it. "A very aggressive program [for magnetic fusion], not quite the Manhattan Project, but aggressive, would be about $1.5 billion per year," said Stewart Prager, director of the Princeton Plasma Physics Laboratory. "To put that in perspective, the United States spends about $1.5 trillion per year on energy."

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC., 202-628-6500