also. For half-lives in the 10~9-to 10~~3-sec range, the same ferromagnetic environment can be used for resonance destruction of the angular distribution. 6 For this range of lifetime one needs to take advantage of the rf-amplitude enhancement in a ferromagnetic lattice while for longer lifetimes this may not be necessary. 7 For conventional spin-rotation measurements in an external magnetic field, the recoil atoms should go into nonmagnetic cubic metals, to avoid as far as possible attenuating interactions. Experiments along these lines are clearly feasible, and preliminary work is in progress.In summary, our results have shown that a large and reasonably uniform degree of alignment is present throughout the neutron and gamma-ray cascades following heavy-ion nuclear reactions. This has been demonstrated to be very useful for spin and multipolarity assignments in spectroscopic studies of the de-exciting product nuclei. It promises to be useful also for studies of the nuclear moments and hyperfine interactions of levels in the product nuclei. Taken together with (1) the wide vari-ety of nuclei that can be produced in compoundnucleus reactions, (2) the broad population of levels in a given product nucleus, and (3) the large uniform recoil velocities of compound nuclei, it makes the use of these reactions a general and powerful tool in nuclear spectroscopy.

The onset of electromagnetic oscillations that are observed in magnetically confined plasmas where beams of fast neutrals are injected is associated with the excitation of a mode with poloidal wave number m° ** 1 and phase velocity equal to the core-ion diamagnetic velocity. The resonant interaction of the mode with the beam ions is viewed as a form of dissipation that allows the release of the mode excitation energy, related to the gradient of the plasma pressure.PACS numbers: 52.35.-g, 52.55.-s A new type of instability has been observed in magnetically confined toroidal plasmas where beams of fast neutrals are injected nearly perpendicular to the equilibrium magnetic field. The poloidal magnetic field fluctuations produced by this instability have a characteristic signature and are called "fishbone oscillations." 1,2 Particle bursts corresponding to loss of energetic beam particles are correlated with fishbone events, reducing the beam heating efficiency and thus limiting the maximum achievable ft [ = (kinetic pressure)/(magnetic pressure)] by this technique.We present the results of an analysis that supports one of the interpretations 3 advanced when these experimental observations were first reported. This consisted of proposing the following: (a) The excited mode, whose spatial structure is dominated by the component with poloidal wave number m 0ass l, has a frequency related to the ion diamagnetic frequency and is one of the two m° = l modes that are found under the conditions for ideal MHD instability, but are rendered marginally stable by finite ion Larmor radius effects 4 ; (b) the mode "excergy" (excitation energy) is related to the plasma pressure gradient; and (c) the presence of a "viscous" dissipative process (e.g., produced by a mode-particle resonance that scatters the beam ions) is required for the instability to develop.We refer, for simplicity, to a large-aspect-ratio axisymmetric toroidal confinement configuration with circular magnetic surfaces, and consider perturbations of the equilibrium field that are dominated by the ra 0as=: l, n 0sss \ poloidal and toroidal components. The relevant model dispersion relation is 4when we omit mode-particle resonances and other dissipative processes. Here, tOdi" -(c/eBrn)dp i± /dr is the ion diamagnetic frequency evaluated at the surface r -TQ where the pitch angle of the unperturbed equilibrium magnetic field equals that of the perturbation, and p ix is the transverse ion pressure. The ideal MHD growth rate 7MHD is given by 4 YMHD^COAXH,where co A = v A9 s/r 0 with v A e ,BS B e I(4Km i ni) U2 , s^dlnq/dlnr, q^rB^/RBe, R is the major radius of the torus, X//-Xo(r 0 //?) 2 (/3p -~/?p,crit), ^o is a finite numerical factor, p p = -(R/ ro) 2 f°drr 2 (dp/dr), and, for a parabolic q profile, 5 Pp.crit 1 ** ^13/12-The ideal stability parameter XH is the negative of the (normalized) minimum value of the perturbed potential energy 4 8W m \ n and the dispersion relation (1) is valid for X H > §.In the realistic limit where 7MHD <^d H the dispersion relation (1)...

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An integral equation governing an instability due to ion temperature gradients is derived. In the presence of magnetic shear, localized non-convective normal modes of instability are shown to exist if the relative temperature gradient is larger than that of density, unless the shear is exceedingly strong, i.e., the field shears through a large angle in the distance in which the temperature drops. Quasi-modes which are less localized in the direction of the gradient can be constructed from these normal modes and a large thermal diffusion may be expected. Conversely the mass diffusion is shown to be rather slow so that it is reasonable to assume that an effective ``divertor'' should keep the actual heat loss quite small.