|
| ©Unknown |
| The laser in action in the lab, the blue glass amplifiers can also be seen |
Prof Ditmire says that when the laser is turned on, it has the power output of more than 2,000 times the output of all power plants in the United States.
The laser is brighter than sunlight on the surface of the sun, but it only lasts for an instant, a 10th of a trillionth of a second (0.0000000000001 second). This is the key to the laser's power - it delivers modest energy in a microscopic unit of time.
Prof Ditmire and his colleagues at the Texas Centre for High-Intensity Laser Science will use the laser to create and study matter at some of the most extreme conditions in the universe, including temperatures greater than those in the sun - when gases break down into a soup of particles called a plasma - and solids at pressures of many billions of atmospheres.
This will allow them to explore many astronomical phenomena in miniature, such as mini-supernovas, tabletop stars and very high-density plasmas that mimic stellar objects.
"We use the laser to heat matter to a condition that is similar to the material one might find in an exotic object like a brown dwarf," says Prof Ditmire. " We create a state which is now often called "warm-dense matter". Such states exist in stellar interiors but we don't understand much about such matter's properties.
"Warm dense matter is interesting, and enigmatic because it is intermediate between the condensed matter state (ie normal solids) and hot plasmas, both states we understand well but both very different from each other. With a petawatt laser we can create such matter in the lab."
"We can learn about these large astronomical objects from tiny reactions in the lab because of the similarity of the mathematical equations that describe the events," says Prof Ditmire, director.
Such a powerful laser will also allow them to study advanced ideas for creating energy by controlled fusion, the same process that powers the Sun. A nozzle will spray clusters of deuterium (heavy hydrogen) atoms into the target chamber of the laser, where the beam will fuse them together, creating fusion power.
This is an alternative to another fusion power method, by confinement in magnetic fields, that will be studied by the vast international Iter fusion project. And the use of lasers this way is a traditional method used to study what happens inside H bomb warheads, as is done by Britain's Helen laser, which is why the facility is funded by the US Energy Department's National Nuclear Security Administration.
Prof Ditmire adds that there is a rival operating petawatt laser in the UK, the Vulcan laser at the Rutherford Appleton Laboratory, Oxfordshire. "The Texas Petawatt now (slightly) exceeds the power of Vulcan," he says, but adds "there has been some very nice science done recently on Vulcan."
To fire up the Texas laser, electrical charge has to be pumped into twenty 20,000-volt capacitors. These capacitors energise the amplification tubes that pump up the energy of the laser light beam. Each tube contains an amplifying material, usually glass, that is "excited" by lamps powered by the capacitors. Every time the laser passes through one of these sheets of glass it gains more energy.
The laser can only be fired in a "clean room," Prof Ditmire says, as it will produce so much power that it could blow apart any dust, hair or clothing fibres that enter the beam.
Another weapon?