A large volume quiescent plasma in a uniform magnetic field

A reasonably uniform cylindrical plasma, 15–20 cm diam, and collisionless for many wave experiments, is generated in fields up to 500 G by applying 200 V of rf at 80 Mc to a fine wire grid stretched across a diameter. Axial containment is provided by opposing sets of μ-metal strips that gather lines of force and create multimirror fields. Drift waves are inhibited by a short range peripheral alternating shear field, produced by an azimuthal ring of bar magnets. Densities are 108−109 ions/cm3 in argon with electron temperatures up to 12 eV, with a noise level, δn / n ≈ 3 × 10−3, over the ion acoustic frequency range.