Please create an account to participate in the Slashdot moderation system

typodupeerror

## Record Setting 500 Trillion-Watt Laser Shot Achieved252

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."
This discussion has been archived. No new comments can be posted.

## Record Setting 500 Trillion-Watt Laser Shot Achieved

• #### Oww, it burns! (Score:4, Informative)

by Anonymous Coward on Monday July 16, 2012 @01:41PM (#40664551)

500 TW is more than one thousand times the *average* power that the entire United States uses at any instant in time.

• #### Re:To put that in perspective (Score:5, Informative)

on Monday July 16, 2012 @01:45PM (#40664597) Journal

Can anyone verify? It was early on a Monday morning, so it could ahve been the haze of the weekend...

• #### Putting the hyperbole in perspective... (Score:3, Informative)

by Anonymous Coward on Monday July 16, 2012 @01:49PM (#40664649)

Off the cuff, 500 TW divided by 1.58 MJ implies the beam lasted only a few nanoseconds. So, "To put those numbers into perspective", 500 TW is more than one thousand times the power that the entire United States uses for a few nanoseconds."

• #### Re:To put that in perspective (Score:5, Informative)

on Monday July 16, 2012 @01:51PM (#40664675)

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.

• #### Re:Putting the hyperbole in perspective... (Score:5, Informative)

on Monday July 16, 2012 @02:19PM (#40665049) Journal

Off the cuff, 500 TW divided by 1.58 MJ implies the beam lasted only a few nanoseconds. So, "To put those numbers into perspective", 500 TW is more than one thousand times the power that the entire United States uses for a few nanoseconds."

Sigh...

You are conflating power with energy. Don't feel bad: the press gets it wrong more than half the time.

Energy is a bulk quantity: a total amount. Power is a rate: how energy over how much time. Because this is /., I'll use a car analogy: energy is analogous to how large the gas tank is (gallons, liters, etc.), power is how quickly that gas gets consumed (g/sec, mL/sec, L/100km, mpg). The average power consumption of the U.S. is a few hundred gigawatts...period. There is no gigawatts per second, or any other monstrous measure that pretends to be power, because the "per second" is already built into the Watt unit.

Correcting your statement: 1.85 MJ is more than one thousand times the energy that the entire United States uses in a few nanoseconds The original statement comparing 500 TW to the (average) power consumption of the U.S. was correct.

• #### Re:Fusion Ignition (Score:5, Informative)

on Monday July 16, 2012 @02:38PM (#40665251)
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...
• #### Re:One Thousand Times (Score:4, Informative)

<miha.cancula@gmail.com> on Monday July 16, 2012 @07:13PM (#40667591) Homepage

Nope. The original definition (by some French guy, according to Wikipedia) was that 1 calorie heats one gram of water by 1 *C. I remember learning that the original definition was for one kilogram, that's why it was called kilocalorie, and was first measured by Joule. Wikipedia contradicts my history knowledge, but not my numbers.

#### Related LinksTop of the: day, week, month.

What's the difference between a computer salesman and a used car salesman? A used car salesman knows when he's lying.

Working...