LIVERMORE, Calif. —  Gov. Arnold Schwarzenegger, who often played futuristic heroes in his movie career, came face-to-face with the world's largest laser system.

The governor went to the Lawrence Livermore nuclear weapons lab in Northern California on Monday and examined its $3.5 billion superlaser, known as the National Ignition Facility.

Work on the stadium-sized project is expected to be completed by March 2009, and scientists said Monday they believe the laser could hold the key to a new source of energy.

It is designed to focus 192 lasers at a single target the size of a pencil eraser to create a huge release of energy known as fusion ignition, the energy source that powers the sun and the stars.

"This laser has many exciting applications," an enthusiastic Schwarzenegger said after reviewing the facility. "What's most exciting about it is the potential to revolutionize our energy future."

The National Ignition Facility will simulate the pressures and heat of a nuclear explosion, meaning scientists can study the performance and readiness of nuclear weapons without detonating a nuclear device.

Tests to determine whether fusion ignition can be achieved are expected to start about a year from now. If it works, scientists say it's possible the technology could be used to generate clean energy.

"If successful, this new endeavor could generate thousands of megawatts of carbon-free nuclear power but without the drawbacks of conventional nuclear plants," said the governor.

Scientists note it will be some time before they know whether the superlaser itself will work and experiments to see if it can create fusion energy are at least two years away. Lab officials say their goal is to have a demonstration project running by 2020.

Speaking to reporters after touring the lab, Schwarzenegger poked fun at his big screen exploits, saying lab officials had briefed him on some highly classified information but warned them that if he shared that information, "I would ... have to terminate you."