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Record Setting 500 Trillion-Watt Laser Shot Achieved
cylonlover writes "Researchers at the Lawrence Livermore National Laboratory's National Ignition Facility (NIF) have achieved a laser shot which boggles the mind: 192 beams delivered an excess of 500 trillion-watts (TW) of peak power and 1.85 megajoules (MJ) of ultraviolet laser light to a target of just two millimeters in diameter. To put those numbers into perspective, 500 TW is more than one thousand times the power that the entire United States uses at any instant in time."
It's a bit more energy than that, but it's not a remarkable amount of energy. 1.85MJ is enough to turn just under 1L of water from 100C liquid phase to 100C vapour phase. ie - it's enough to boil 1L of water, if the water is already at the boiling point.
Latent heat of vapourization for H2O is about 2200 kJ/kg.
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Lasers are not normally used in Tokamak reactors. In those systems, the idea is to use magnetic fields to hold a plasma tight enough (and long enough) for fusion to initiate. The energy input (i.e. "heating") is done ohmically, that is, by radio waves that induce electric currents in the gas. The NIF pursues a different approach, called "inertial confinement fusion." The idea in these systems is to supply a whole load of energy in a very short time, so the hydrogen nuclei don't have time to move apart before the fusion reaction takes place. That is, their inertia is what confines them long enough for the reaction to go. In order to do this, you need a giant load of energy delivered into a very small volume in a very short time. That's why they quote the number as terawatts. The interesting part of this announcement is not just the TW energy rate, but the nanosecond-scale pulse width. This is actually pretty cool news...