10 Inertial confinement fusion: heavy ions

Trends in heavy ion interaction with plasma

“…This effect is especially pronounced at low ion energies (E < 100 keV/u) where an enhancement factor of up to 35 has been observed (Bock et al, 2005). This effect is less dramatic at higher projectile energies (E > 1 MeV/u), but is still in the order of 2-3, depending on the projectile ion species, and the free electron density of the plasma (Hoffmann et al, 1990;Dietrich et al, 1992;Jacoby et al, 1995).…”

“…The motivations are mainly listed as follows: (1) the energy deposition process of heavy ions in ionized matter is one of the most important processes of heavy-ion-driven high energy density and ICF; (2) Plasma devices could be served as an important accelerator equipment to focus ion beams (socalled plasma lens), and or to strip ion beams (so-called plasma stripper). Beside these applications, such research is also an important fundamental topic to understand the atomic processes in plasma, such as the di-electron recombination process, the radiative electron capture process, and the effective charge in Coulomb interaction process, and so on (Sigmund, 1969;Hoffmann et al, 1990;Dietrich et al, 1992;Jacoby et al, 1995;Golubev et al, 2001;Sharkov, 2001;Bock et al, 2005;Logan et al, 2005;Tahir et al, 2005;Piriz et al, 2006;Zhao et al, 2009;Teske et al, 2010;Tahir et al, 2010;Pikuz et al, 2010;Xin et al, 2010;Zhang et al, 2011).…”

Nuclear diagnostics for Inertial Confinement Fusion (ICF) plasmas

“…As a result, a large body of theoretical and computational work was conducted in the United States (US), Europe, Japan and the Union of Soviet Socialist Republics (USSR) in the 60s and early 70s, which laid the foundation for laser-driven ICF, both in direct-drive mode (where lasers directly illuminate the capsule), and indirect-drive mode (where lasers illuminate the inside of a hohlraum for production of x-rays that drive the capsule). Other types of driver concepts were also investigated such as electrons, heavy ions and magnetic fields [3,4]. This era culminated in 1972 with the first unclassified ICF paper 'Laser Compression of Matter to Super-High Densities' published by Nuckolls et al in Nature [5], which formulates the foundation for the directdrive ICF scheme where 100 kJ-1 MJ lasers are used to implode a millimeter-sized spherical capsule, filled with DT gas, to densities and temperatures high enough for significant thermonuclear fusion, ignition and energy gain to occur.…”

“…As discussed in the literature [44], a simple form that represents the ignition condition for a steady-state plasma can be derived by balancing the alpha-power density with the power-loss density mainly due to heat loss caused by fuelshell expansion and thermal conduction 3 . Often referred to a Lawson-type criterion, the ideal ignition condition is expressed as where ε α is the kinetic energy of the DT-alpha, n is the total ion-number density, 〈σv〉 is the fusion reactivity for a thermal plasma, P is the hot-spot pressure, T i is the hot-spot ion temperature, and τ E is the energy-confinement time 4 . Here, it is assumed that the pressure profile is constant in the hot spot and thus can be expressed as P=2nT i .…”

“…3 When the density in the surrounding fuel-shell is high, most of the radiation is absorbed in the fuel-shell and the energy is recycled back into the hot spot by increasing the ablation of the inner surface of the fuel-shell. 4 τ E represents the characteristic plasma-energy relaxation time due to electron heat conduction. ∼20 atm s (and not Pτ E,min ∼8 atm s, which is required for a T i of ∼13 keV).…”