KRYPTON-FLUORIDE LASERS


Laser Creation     Requirements for Pellet Energy Gain     Laser Beam Smoothing Requirements


Laser Creation: When electrical energy flows through a gas containing krypton and fluorine, molecules of KrF can be formed in an excited state. If light shines on the molecules before they naturally dissociate, the dissociation can be stimulated, thereby creating a laser (light amplification by stimulated emission of radiation)



(Electron energy) + Kr + F2 => KrF* + F => Kr + F2 + light

KrF Laser Diagram

A high-voltage pulsed-power source generates a uniform electron beam from the cathode. The electron beam propagates through the foil support and deposits its energy in the laser cell, filled with krypton, fluorine and argon gases. A complex set of ionizations and chemical reactions produce the excited molecular state of KrF*. The input laser beam them stimulates the decay of this molecule to its ground state of separate atoms, with an enhancement of the laser intensity.

Why use lasers to heat fuel pellets? The energy in each shot is not very large, but the time duration of the energy is very short. As a result, the power level is very high. A laser can thus heat plasmas to high temperatures and generate high pressures.

Some Laser Parameters Required to Implode a Fusion Pellet

Laser Energy

  • About 1.5 megajoules. This equals the energy required to heat 1 gallon of water from 0°C to 100°C

Duration of the Laser Light

  • Four billionths of a second for the high-power portion of the pulse. Light can travel four feet in this time interval.

Laser Power ( = energy / duration)

  • 4 x 1014 Watts. This peak power is 500 times higher than the electric power output of the entire U.S. electrical grid.

Laser Creation     Requirements for Pellet Energy Gain     Laser Beam Smoothing Requirements