Realization of fusion energy imposes considerable challenges in the areas of producing cryogenic targets with an isotropic fuel structure and developing noncontact target delivery means. It was shown that the FST-layering method using high cooling rates (1–50 K s−1) and high-melting additives to fuel content (0.3%–25%) makes solid layers isotropic and free of local defects. FST-layering in line-moving shells is usually realized in a vertical single-spiral layering channel. Here we present our first results with a double-spiral layering channel (DS-LC). The cryogenic layers (D2 + 20% Ne) were formed in 5 shells (2R ∼ 1.8 mm) during their rolling in the DS-LC, and then they were gravitationally injected to the test chamber at T = 5 K. The obtained isotropic layers (W ∼ 87 μm) are stable in the temperature range from 5 K to Ttp = 18.7 K of D2. The total layering time <20 s. Another critical issue is the noncontact target delivery. It is shown that using transport of high-temperature superconductors in the magnetic fields provides stable noncontact target acceleration placed in a superconducting sabot. The proof-of-principle experiments have shown that using only 1 field coil allows one to accelerate such sabot up to 1 m s−1. Computationally, it has been shown that acceleration up to a velocity of 200 m s−1 will require about 200 field coils (0.25 T each) along the 5 m-length of the linear accelerator with overloads a = 400 g; the velocity of 400 m s−1 will require the acceleration length of 20 m at the same a = 400 g. First steps are made to reduce the dimensions of the linear accelerator using a cyclic permanent magnet guideway with less than 10 field coils to achieve target injection velocities in the range of Vinj = 200–400 m s−1.
Enhancement of proton acceleration via geometric confinement in near critical density plasma-filled targets