Steadily running self-focusing streams

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Abstracts

35 kV. In a second type of experiment a very large bank of condensers is used giving a stored energy of about 1 million joule, which induces a variable toroidal magnetic field with a time constant of about 1 msec. This produces an H centred pinch. P/342. Study of Electromagnetic Transitions in Light Nuclei by means of the Method of Angular Correlations of Pairs of Internal Conversion. S. GORODETZKY(F~~IIC+ Monopolar pairs. Electromagnetic transitions between nuclear levels compete with the relatively rare process of internal conversion pairs. It is possible to demonstrate that the angular correlation of such a pair is very sensitive to the multipole order of the corresponding electromagnetic transition. Experimental measure of the correlation demonstrated the multipolarity of 7 transitions. In order that, amongst the numerous transitions appearing in a nucleus, those which are to be studied may be isolated, the following process has been used: the energy of each of the electrons of the pairs is measured separately (this energy is spread out over a continuous spectrum); then the results are summed and the sum corresponds to the energy of the y transition. A certain number of transitions have thus been characterized, allowing, in addition, the assignation of spin and parity to the levels concerned in the transition. The phenomenon of monopolar pairs is similar. It appears, for example, in the transitions 0+0+ (oxygen). Electromagnetic transition is naturally prohibited. The transition occurs by pairs. The angular correlation of these pairs has been computed for a long time with the Dirac Theory. A more rigorous calculation, using modern quantic electrodynamics, gives a slightly different result, especially at angles 0” and 180”. This effect, which is diEcult to obtain experimentally, would be of great interest if it could be realized. Attempts along this line are in progress. P/344. Description of the Oak Ridge Thermonuclear Experiment (DCX). P. R. BELL, J. S. LUCE, E. D. SHIPLEY and A. SIMON (U.S.A.). The DCX is a device which is designed to grow a hot plasma by the trapping of energetic particles in a magnetic field. This injection and trapping has already been accomplished and work is now under way which should lead to development of the plasma. Experimental results, including details of the trapping mechanism will be discussed. Theoretical discussion will include the expected final characteristics of the device, as well as a description of intermediate stages in the formation of the plasma.

P/345. High Temperature Plasmas Produced by the Magnetic Compression of Shock-preheated Deuterium. A. C. KOLB (U.S.A.). It has been demonstrated that high velocity shock waves with ion energies greater than lOOeV/ion can be produced by the magnetic acceleration of a deuterium plasma. The plasma is then channeled and compressed by means of pulsed magnetic fields along the axis of the shock lube. Experimental results-for ambient pressures from 0.1 + 1.0 mm He and maenetic fields of l&000-700,000 gauss &l be rep&ted. The time scale of these experiments is from 2-20 microseconds with peak currents of the order 8 x lo6 amperes. Optical observations of the compression, stability, and shock velocity will be discussed together with spectroscopic observations of the emitted radiation. P/346. Steadily Running Self-Focusing Streams. WILLARDH. BENNETT(U.S.A.). A method is proposed for producing a steadily running self-focusing stream of relativistic electrons and space charge neutralizing ions in a closed loop. Electrons from a linear accelerator are injected at full energy into a magnetic guide field similar in form to that of a cyclotron. The electrons injected in each pulse are held in the field durhig the injection pulse with the assistance of Tuck and Teng peeler and regenerator field bumps in reverse aider, although t&e action is not strictlv the reverse of the Tuck and Teng svstem. Follo&ing each injection pulse, the rad&s’of the injected loop is shrunk by an increase in guide field long enough for the electrons to radiate energy and shrink in loop radius too much to escape. By successive injections of electrons, the cycling current is built up to the minimum critical value for self-focusing and held there. P/347. Theory of Pinch Effect-Stability and Heating. MARSHALLN. ROSENBLUI~I (U.S.A.). It can be shown by methods given elsewhere that the magneto-hydrodynamic equations are valid for theiimple $nchgeometryspecified by B.&l B.M. One finds that an internal B. and an external conductor tend to stabilize the pinch. The characteristic equation for stability can be written as a single second-order differential equation for a given perturbation of the form ei(kz+4). A code has been developed for its solution with various equilibria. In the case of a thin surface layer, previous treatments may be shown to be incorrect due to the presence of a singularity existing within the layer. This singularity develops at a radius such that the field lines represent a constant phase of the perturbation. Unfortunately, the stability requirements become more stringent, and depend “\

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