  The plasma lens concept is examined as an alternative to focusing horns and
solenoids for a neutrino beam facility. The concept is based on a combined
high-current lens/target configuration. Current is fed at an electrode located
downstream from the beginning of the target where pion capturing is needed. The
current is carried by plasma outside the target. A second plasma lens section,
with an additional current feed, follows the target. The plasma is immersed in
a relatively small solenoidal magnetic field to facilitate its current profile
shaping to optimize pion capture. Simulations of the not yet fully optimized
configuration yielded a 25% higher neutrino flux at a detector situated at 3 km
from the target than the horn system for the entire energy spectrum and a
factor of 2.5 higher flux for neutrinos with energy larger than 3 GeV. A major
advantage of plasma lenses is in background reduction. In antineutrino
operation, neutrino background is reduced by a factor of close to 3 for the
whole spectrum, and for energy larger than 3 GeV, neutrino background is
reduced by a factor of 3.6. Plasma lenses have additional advantages: larger
axial currents, high signal purity: minimal neutrino background in antineutrino
runs. The lens medium consists of plasma, consequently, particle absorption and
scattering is negligible. Withstanding high mechanical and thermal stresses in
a plasma is not an issue.
