3 ms·

In-Target Proton–Boron Nuclear Fusion Using a PW-Class Laser

44 points by taubek 5y ago

perihelions 5y ago
[dupe] https://news.ycombinator.com/item?id=30841080 https://news.ycombinator.com/item?id=30841080
- andreareina 5y ago
  Different content, not a dupe. This is the actual paper as opposed to a press release. It's good to have both.
  - wanda 5y ago
    So link to one in the other's comments.
    - jrootabega 5y ago
      Perhaps if we squeeze these two submissions together fast enough they will fuse.
      - deleted 5y ago
        [deleted]
    - bharath4321 5y ago
willis936 5y ago
The laser efficiency alone keeps ICF reactors as a pie in the sky. p-B11 is attractive but the Bremsstrahlung emissions of the heavy/highly ionized boron would exceed the power output of a steady state reactor. So knock on neutrons all you want: until you bridge 10 orders of magnitude aneutronic fusion won't be supplying anyone with power. Keep up the good work, but don't expect results in your lifetime.
pfdietz 5y ago
HB11 is proposing to use an "avalanche" mechanism where alpha particles from the fusion run into and accelerate protons to energies > thermal to continue the reactions (a chain reaction). Unfortunately, this doesn't appear to work, by about two orders of magnitude. https://iopscience.iop.org/article/10.1088/1361-6587/abf255 https://iopscience.iop.org/article/10.1088/1361-6587/abf255 Their proposed direct conversion scheme is also problematic, for several reasons (electrons would short out the spherical capacitor, the necessary ion current greatly exceeds the space charge limit on the current, and the alpha particles from p-11B are not monoenergetic, especially after the scattering necessary for their putative avalanche scheme, meaning that ions would either not have enough energy to reach the collecting electrode or would reach it with so much kinetic energy the surface of the electrode would experience too much heating.)
upsidesinclude 5y ago
The technical hurdles to inertial confinement fusion are so absurd. Even were the output energies substantial enough to justify the cost of a production generator it would take decades to have a functioning mechanism to deliver the fuel with beam integrity. Physicists are amazing at trivializing engineer feats and love nuclear weapons funding. This is weapons research and that's it, talking about any other scientific validity has always been a weak attempt to give it some moral ground

44 points by taubek 5y ago

perihelions 5y ago

[dupe] https://news.ycombinator.com/item?id=30841080 https://news.ycombinator.com/item?id=30841080

andreareina 5y ago
Different content, not a dupe. This is the actual paper as opposed to a press release. It's good to have both.
- wanda 5y ago
  So link to one in the other's comments.
  - jrootabega 5y ago
    Perhaps if we squeeze these two submissions together fast enough they will fuse.
    - deleted 5y ago
      [deleted]
  - bharath4321 5y ago

willis936 5y ago

The laser efficiency alone keeps ICF reactors as a pie in the sky. p-B11 is attractive but the Bremsstrahlung emissions of the heavy/highly ionized boron would exceed the power output of a steady state reactor. So knock on neutrons all you want: until you bridge 10 orders of magnitude aneutronic fusion won't be supplying anyone with power. Keep up the good work, but don't expect results in your lifetime.

pfdietz 5y ago

HB11 is proposing to use an "avalanche" mechanism where alpha particles from the fusion run into and accelerate protons to energies > thermal to continue the reactions (a chain reaction). Unfortunately, this doesn't appear to work, by about two orders of magnitude. https://iopscience.iop.org/article/10.1088/1361-6587/abf255 https://iopscience.iop.org/article/10.1088/1361-6587/abf255 Their proposed direct conversion scheme is also problematic, for several reasons (electrons would short out the spherical capacitor, the necessary ion current greatly exceeds the space charge limit on the current, and the alpha particles from p-11B are not monoenergetic, especially after the scattering necessary for their putative avalanche scheme, meaning that ions would either not have enough energy to reach the collecting electrode or would reach it with so much kinetic energy the surface of the electrode would experience too much heating.)

upsidesinclude 5y ago

The technical hurdles to inertial confinement fusion are so absurd. Even were the output energies substantial enough to justify the cost of a production generator it would take decades to have a functioning mechanism to deliver the fuel with beam integrity. Physicists are amazing at trivializing engineer feats and love nuclear weapons funding. This is weapons research and that's it, talking about any other scientific validity has always been a weak attempt to give it some moral ground