Using a kinetic-theoretic approach to Fokker-Planck equilibrium of thermonuclear ␣ particles in dense and magnetized plasmas, the corresponding longitudinal dielectric function is investigated at length. It is used to evaluate the energy loss of the ␣ s Ј through the excitation of collective plasma modes. Specific attention was paid to the case of extreme magnetization, as well as to the parallel stopping of ␣ particles in dense and hot plasmas of magnetized target fusion ͑MTF͒ interest. Maximum stopping is shown to be strongly dependent on magnetic field intensity.

Using the longitudinal dielectric function derived previously for charged test particles in helical movement around magnetic field lines, the numerical convergence of the series involved is found and the double numerical integrations on wave vector components are performed yielding the stopping power for arbitrary angle between the test particle velocity and magnetic field. Calculations are performed for particle Larmor radius larger and shorter than Debye length, i.e., for protons in a cold magnetized plasma and for thermonuclear α particles in a dense, hot, and strongly magnetized plasma. A strong decrease is found for the energy loss as the angle varies from 0 to π∕2. The range of thermonuclear α particles as a function of the velocity angle with respect to the magnetic field is also given.

In connection with fundamental issues relevant to magnetized target fusion, the distribution function of thermonuclear alpha particles produced in situ in a dense, hot, and strongly magnetized hydrogenic plasma considered fully ionized in a cylindrical geometry is investigated. The latter is assumed in local thermodynamic equilibrium with Maxwellian charged particles. The approach is based on the Fokker–Planck equation with isotropic source S and loss s terms, which may be taken arbitrarily under the proviso that they remain compatible with a steady state. A novel and general expression is then proposed for the isotropic and stationary distribution f(v). Its time-dependent extension is worked out numerically. The solutions are valid for any particle velocity v and plasma temperature T. Higher order magnetic and collisional corrections are also obtained for electron gyroradius larger than Debye length. f(v) moments provide particle diffusion coefficient and heat thermal conductivity. Their scaling on collision time departs from Braginski’s.