9.29.2012
OHMIC HEATING
Heating in addition to Ohmic heating. Used to heat tokamaks to temperatures at which Ohmic heating is no longer efficient. Usually involves the use of neutral beams of high energy particles or radio-frequency waves.
9.28.2012
9.27.2012
9.24.2012
9.22.2012
9.20.2012
COLLISIONALITY
A measure of how frequently collisions occur in a tokamak plasma. A collisionality of unity corresponds to a trapped particle performing a single banana orbit before being scattered. The collisionality drops as the plasma temperature rises.
9.18.2012
9.10.2012
9.06.2012
9.05.2012
MARK OLIPHANT
"All the hydrogen burns into helium in 10 million years.... All the helium burns to carbon in 1 million years.... Again, the star starts to collapse, because there's no more fuel. But then it heats up and the carbon starts to burn ... to form neon and nitrogen. And all of the carbon in the star burns in 100 thousand years.... And you get to oxygen. Oxygen ... burns to silicon in 10 thousand years. It's getting hotter and hotter and hotter. Less efficient. And then when all the oxygen burns to silicon, you're in the last day of the star because, remarkably, it is so hot at that point that all of the silicon in the center of the star, many thousands of times the mass of the Earth, burns to form iron in one day.... Iron can't burn to form anything. Iron is the most tightly-bound nucleus in nature. So once that's happened, there's no more fuel... When all the silicon has burned to iron, suddenly the star realizes there's no place left to go and that interior of the star, which has been held up by the pressure of nuclear burning, collapses. That whole collapse happens in one second.... There's a shock wave and that shock wave ... spews out all of the atoms that were created during the life history of a star. The carbon, the nitrogen, the helium, the iron. And that's vitally important, because every atom in your body was once inside a star that exploded.... The atoms in your left hand probably came from a different star than in your right hand, because 200 million stars have exploded to make up the atoms in your body."
9.04.2012
LAWRENCE KRAUSS
“Every atom in your body came from a star that exploded. And, the atoms in your left hand probably came from a different star than your right hand. It really is the most poetic thing I know about physics: You are all stardust. You couldn’t be here if stars hadn’t exploded, because the elements - the carbon, nitrogen, oxygen, iron, all the things that matter for evolution and for life - weren’t created at the beginning of time. They were created in the nuclear furnaces of stars, and the only way for them to get into your body is if those stars were kind enough to explode.... The stars died so that you could be here today
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