A convective mechanism for inhibition of heat conduction in laser produced plasmas
Abstract
In laser-produced plasmas, the laser energy is absorbed only below and up to the critical density. For laser fusion applications, this energy must be transported beyond the corona via electron thermal conduction towards colder, higher density regions of the target to heat up material and cause ablation, which in turn generates an inward pressure to compress the fusion fuel. If the heat conduction is inhibited, the consequences are a weaker ablation and therefore a weaker implosion. For many years now, the inhibition of heat conduction, i.e., the reduction of heat conduction relative to classical conduction, in laser-produced plasmas at relevant irradiances was apparent from the large body of experimental evidence. Many mechanisms, such as dc magnetic fields, ion acoustic turbulence, and Weibel instabilities, were proposed to be the cause of inhibition of heat conduction. Even improved calculations of the classical heat flux were carried out to solve this problem. Nevertheless, no single one of the above mentioned mechanisms explains the large inhibition observed in the experiments.
- Publication:
-
Presented at the Intern. Conf. on Plasma Phys
- Pub Date:
- June 1984
- Bibcode:
- 1984plph.confT....L
- Keywords:
-
- Conductive Heat Transfer;
- Laser Plasmas;
- Thermal Conductivity;
- Ablation;
- Energy Transfer;
- Flow Velocity;
- Laser Targets;
- Numerical Analysis;
- Plasma Density;
- Pressure Effects;
- Lasers and Masers