Inertial confinement fusion (ICF) target applications of strongly coupled dense plasmas to plasma heating

Seongsu An, Purdue University

Abstract

During the burn of DT (Deuterium-Tritium) fuel in ICF (Inertial Confinement Fusion) target, the energy deposition of fusion-product charged particles is an important problem that recently received again increasing attention. The unified theory explains the energy losses due to binary and collective collisions in the dilute plasmas, and also in the condensed matter physics for the case of plasma parameter less than one, i.e., g<1, which is related to the number of particles in the Debye radius. The ignition of an ICF DT target produces 3.5MeV alpha particles, which are under extremely high-energies compared to the temperature of field plasmas at around 3-5 keV. At the incidence of a fast alpha particle (3.5MeV) into ionized plasmas as a fusion product, the incoming fast ion loses its energy to the charged particles inside the target, called an ensemble system, by way of primarily Coulomb collisions. At dilute plasmas, i.e., plasma parameter g<1, the unified theory is well accounted for the energy loss of an alpha particle. However, at dense plasmas, especially for plasma parameter g>1, there is an extraordinary situation occurred that is caused by ionized field-electrons. Normally an incident ion should lose its energy to the field plasmas due to two-body and many-body collisions. When the velocity of an incident ion is less than that of field-electrons, those free electrons can make a contribution to the incident ion paradoxically by way of collisions among field electrons. Those collisional contributions among field electrons to the incident fast ion via collective phenomena for this particular situation should be taken into account in the unified theory. In the mathematical description of energy losses, the unified theory, which is valid only in the plasma parameter [special characters omitted], cannot include the collective phenomenon which is the collisions among the field charged particles in dense plasmas. The inclusion of collisions among charged particles in the background, via collective phenomena into the existing unified theory, is very difficult because the strong interaction at short range may cause the Debye sphere distorted and further suggests non-particle interactions. By renormalizing the distribution function and including the local field corrections at short range, the unified theory can be made valid for both plasma parameter, i.e., g<1 and g>1 regions, called Modified Unified Theory. The modified unification theory obtained shows more accurate energy loss of an incident ion, for example, a 67% increase of energy losses at the plasma parameter, g=3, for an alpha particle slowing down in dense DT plasmas. It is thus important to consider the modified unified theory for ICF target application for the self-sustaining of an ICF target by way of fusion product heating.

Degree

Ph.D.

Advisors

Choi, Purdue University.

Subject Area

Nuclear engineering|Plasma physics|Nuclear physics

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