The addition of a certain fraction of ions to an otherwise stable cloud of electrons can in certain circumstances result in an instability.The case of a low density (q = o electron motions can be described by 5 t v detail.ion orbits (which characteristically t r a v e r s e the entire electron cloud) should involve frequencies close to that of the diocotron wave that can propagate on the electron cloud. the ratio Z m /m.q of the order of unity and i s independent of the ion density, When instability is present, the growth rate is of the order << 1) electron cloud in which the p/"c x B, = 0 is considered in -e

Injection and containment of unneutralized clouds of electrons has been accomplished with an azimuthally symmetric, toroidal, magnetic field. The confining magnetic field is produced within a conducting toroidal chamber. The induction of this magnetic field has been used to inject the electron cloud (inductive charging). Average electron densities of 4 × 109 cm−3 and peak electrostatic well depths of ≈ 400 kV have been achieved. Semiempirical correlations are given which show the inductive charging scheme to be governed by an electron energy restriction and finally limited by the occurrence of anomalous crossed field beam noise. Stable equilibria, without the necessity of a rotational transform have been observed for times in excess of 60 μsec. Correlation of the containment time observations with the predictions of a theoretical model for an ion-diocotron wave instability shows that the containment time is governed by the rate of ionization of the residual neutral gas (p &gt; 10−7 Torr) in the apparatus. The correlation of theory and experiment appear to confirm the theoretical prediction that a significant degree of charge neutralization (in the range of 10-20%) can be stably contained. Interpretation of these results suggests that significant improvement in both electron cloud density and containment time should be possible.

The self-consistent equilibrium configurations available to low-density (q = ωp2/ωc2 ≪ 1) toroidal electron clouds under the influence of an external magnetic field and the electric fields due to space and image charges are discussed. The equilibria are dynamic rather than static, but steady. ▿B, centrifugal, and other drifts are shown to be unimportant, in contrast to the situation in toroidal neutral plasmas. Typical equilibria are shown in detail, to zero order in q. The construction of equilibria accurate to order q is shown to be possible but is not carried out in detail. Questions relating to the stability of these equilibria are not treated.

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Efficient electron-beam initiation of an atmospheric-pressure HF chain-reaction laser has been demonstrated. Intrinsic electrical efficiencies of up to 875% have been observed with laser output energy densities of up to 51 J/liter atm at low initiation levels. This result was obtained for a laser mixture containing H2:F2:He:O2 at mole fractions of 0.08:0.30:0.61:0.01. Laser output energy was extracted from a volume of 104 cm3.