A first for direct-drive fusion

Scientists at the University of Rochester have taken a significant step forward in laser fusion research.

Read more at: http://phys.org/news/2016-09-direct-drive-fusion.html#jCp

CrazyNeutrino said:

A first for direct-drive fusion

Scientists at the University of Rochester have taken a significant step forward in laser fusion research.

Read more at: http://phys.org/news/2016-09-direct-drive-fusion.html#jCp

So, “direct drive” means laser force generates compression directly.
And “indirect drive” means lasers create X-rays that generate compression.

“the conditions at LLE, if and only if replicated at the NIF, could produce over 100 kilojoules (kJ) of fusion energy, which is the energy of a 100-watt light for about 20 minutes”.

mollwollfumble said:

CrazyNeutrino said:

A first for direct-drive fusion

Scientists at the University of Rochester have taken a significant step forward in laser fusion research.

Read more at: http://phys.org/news/2016-09-direct-drive-fusion.html#jCp

So, “direct drive” means laser force generates compression directly.
And “indirect drive” means lasers create X-rays that generate compression.

“the conditions at LLE, if and only if replicated at the NIF, could produce over 100 kilojoules (kJ) of fusion energy, which is the energy of a 100-watt light for about 20 minutes”.

They will compress down to Gamma Rays next?

CrazyNeutrino said:

mollwollfumble said:

CrazyNeutrino said:

A first for direct-drive fusion

Scientists at the University of Rochester have taken a significant step forward in laser fusion research.

Read more at: http://phys.org/news/2016-09-direct-drive-fusion.html#jCp

So, “direct drive” means laser force generates compression directly.
And “indirect drive” means lasers create X-rays that generate compression.

“the conditions at LLE, if and only if replicated at the NIF, could produce over 100 kilojoules (kJ) of fusion energy, which is the energy of a 100-watt light for about 20 minutes”.

They will compress down to Gamma Rays next?

Actually, on second thoughts the “X-rays” disagrees with my previous understanding. I’d better check. No, they’re right,

Ions or electrons could have been used instead of lasers.

From Wikipedia:
“Certain targets are surrounded by a small metal cylinder which is irradiated by the laser beams instead of the target itself, an approach known as “indirect drive”. In this approach the lasers are focused on the inner side of the cylinder, heating it to a superhot plasma which radiates mostly in X-rays. The X-rays from this plasma are then absorbed by the target surface, imploding it in the same way as if it had been hit with the lasers directly. The absorption of thermal X-rays by the target is more efficient than the direct absorption of laser light, however these hohlraums or “burning chambers” also take up considerable energy to heat on their own thus significantly reducing the overall efficiency of laser-to-target energy transfer. They are thus a debated feature even today; the equally numerous “direct-drive” design does not use them. Most often, indirect drive hohlraum targets are used to simulate thermonuclear weapons tests due to the fact that the fusion fuel in them is also imploded mainly by X-ray radiation.”

So the X-rays are used to imitate the effect of an H-bomb. Hmm.