Voz. UMs 32, NUMaza 20 PHYSICAL RE VIE%' LETTERS 20MA~ jy74 In conclusion, we have measured the contain- ment of high-P plasmas (P =0.3 to 0. 4) in the 2XII magnetic mirror device and have observed evidence of a P limit. The magnitude and time dependence of this limit were consistent with those predicted for the mirror instability. A number of discussions with L. S. Hall, T. K. Fowler, R. F. Post, and C. J. H. Watson on high- P equilibria are gratefully acknowledged. *Work performed under the auspices of the U. S. Atomic Energy Commission. R. A. Dandl, H. O. Eason, P. H. Edmonds, A. C. England, G. E. Guest, C. L. Hedrick, J. T. Hogan, and J. C. Sprott, in Proceedings of the Fourth Inter- national Conference on Plasma Physics and Controlled Nuclear Fusion Research, Madison, 9'isconsin, 2'971 (International Atomic Energy Agency, Vienna, Austria, 1972), Vol. 2, p. 607. 2For example, see H. P. Eubank, P. Noll, and F. Trappert, Nucl. Fusion 5, 68 {1965); V. A. Finlay- son, F. H. Coensgen, and W. E. Nexsen, Jr. , Nucl. Fusion 12, 659 (1972). 3W. S. Cooper, K. H. Berkner, and R. V. Pyle, Nucl. Fusion 12, 263 (1972); and K. %. Ehlers and W. B. Kunkel, in Proceedings of the Second International Con- ference on Eon Sources, Vienna, Austria, 1972, edited by I. Viehboeck, H. Winter, and M. Bruck (Oster- reichische Studiengesellschaft fur Atomenergie GmbH, Vienna, Austria, 1972), p. 259. 4W. F. Cummins, Rev. Sci. Instrum. 41, 234 (1970). 5T. C. Simonen, F. H. Coensgen, W. F. Cummins, W. E. Nexsen, Jr. , A. W. Molvik, and B. W. Stallard, Bull. Amer. Phys. Soc. 18, 1320 (1973). W. E. Nexson, Jr. , W. F. Cummins, F. H. Coensgen, A. W. Molvik, and T. C. Simonen, Bull. Amer. Phys. Soc. 17, 985 (1972). 7J. G. Cordey and C. J. H. Watson, in Proceedings of British Nuclear Fnergy Society Conference on Nu- clear Fusion Reactors, Culham Laboratory, 1969 (United Kingdom Atomic Energy Authority, Culham, England, 1970), p. 122. I . S. Hall, Phys. Flu, ids 15, 882 (1972). ~J. P. Holdren, Nucl. Fusion 12, 267 (&972). For convenience, we will follow the custom of re- ferring to this as the mirror instability, although this condition more precisely refers to the maximum per- pendicular P for which equilibrium exists. ~'J. G. Cordey and C. J. H. Watson, Nucl. Fusion 12, 287 (1972). L. S. Hall and T. C. Simonen, to be published. Dynamics of Charged Macromolecules in Solution* Dale %. Schaefer Sandia Laboratories, Albuquerque, ¹MMexico 87115 Bruce J. Berne DePartment of Chemistry, Columbia University, ¹m York, Nero York 10027 (Received 26 March 1974) Analysis of the scattered intensity and photocount correlation function of light scattered from charged R17 virus indicates incipient macromolecular ordering. If a coherent light source is focused on a mac- romolecular solution, fluctuations are observed in the scattered light intensity. Fluctuations re- sult since motion of the particles produces a con- stantly changing interference condition at the de- tector. ' If the positions of the particles are un- correlated, it is well established that the decay rate of intensity fluctuations is directly propor- tional to macromolecular diffusion constant. ' In the case of solutions in which the range of interparticle interaction is comparable to the in- terparticle distance d, mac rvmolecular dynam- ics have remained quite obscure. This is the case, not only because of the theoretical diffi- culties associated with many-body systems, but also because of limited experimental data. In order to elucidate this problem we present data on both the magnitude and time dependence of light scattered from solutions of charged macro- molecules (R17 virus) in which the range of the electrostatic interaction & is comparable to d. Both the scattered intensity and the decay rate I' of the field correlation function depend strongly on scattering angle indicating incipient transla- tional ordering. These data are interpreted by the Zwanzig-Mori projection-operator forma- lism, ' ' through which we demonstrate that the dependence of I' on scattering angle is largely 4110