Peaceful uses of fusion

Peaceful uses of fusion

304 Abstracts drawn will be given. These results are interpreted in terms of the dynamics of the discharge and attempts will be made to correlate th...

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drawn will be given. These results are interpreted in terms of the dynamics of the discharge and attempts will be made to correlate them with temperature and particle-density estimates. Neutrons are produced in discharges of low initial pressure and high peak current when the current is suitably programmed. The possibility of thermonuclear and other methods of neutron production will be discussed. P/2350. The Isolation of a Denterinm Plasma from Wall Emitted Impurities by the Use of an Intervening Plasma. H. DREICER(U.S.A.). In this paper we wish to report on a new concept which deals with the isolation of deuterium plasmas from wall emitted impurities by the use of a so called “plasma shield” located between plasma and wall. Theoretical estimates based upon the rates of impurity ionization, subsequent diffusion across magnetic fields, and drifts produced by crossed electric and magnetic fields show that shields of reasonable thickness may be efficient in trapping impurities. Cylindrical plasma shields coaxial to and surrounding a cylindrical plasma have been produced in the Currents of several hundred laboratory. thousand amperes have been passed along the axis and returned by the shield plasma. Current distributions as a function of applied magnetic field and gas pressure are described. P/2394. Columbus II (A High Powered Linear Pinch Machine). D. C. HAGERMAN, J. W. MATHERand A. H. WILLIAMS(U.S.A.). The linear pinch machine, Columbus II, with discharge tube 30 cm long and 10 cm id., is designed to operate at 100 kV, 1.5 x 106 amperes discharge current and 2 microseconds rise time. Operation is limited above 60 kV and 36,000 joules by failure of the discharge to start break away from the tube wall. Experimental evidence for this process is presented. The effect of an axial magnetic field on the production of neutrons suggests that several mechanisms are responsible for the observed neutrons. Typically 100, 500 and 4,500 gauss decrease the neutron production by a factor of 3, 10 and -100 respectively from the zero gauss yield. Peak yields of 6 x 108 neutrons for burst have been measured at 40 kV (16,000 joules). The axial neutron energy measured at B,, the cathode decreases with increasing 2.72 MeV (zero field), 258 MeV (100 gauss) and 2.55 MeV (500 gauss). The significance of the neutron energy shift and the high neutron yields are discussed in terms of simple pinch models.

A detailed study of the distribution of magnetic fields in a stabilized linear pinched discharge (Columbus S-4) has demonstrated a tendency of the discharge to lock its magnetic energy inside the tube thyough ionization-of gases r&naining external to the ninth. This effect is seen as a circulation of currents in the tube, in some cases reaching half the peak value of the discharge current even though the current from the external capacitor bank has returned to zero. It is shown through elementary arguments that this effect should be most pronounced for discharge tubes of large bore, coupled to short-period capacitor banks. Analysis of the discharge spectrum shows a remarkable absence of electrode materials in the discharge, even though wall elements are abundant. Measurement of plasma pressure distribution indicates much less cooling near the electrodes than simple theory would suggest. Instabilitv studies indicate that small-area surface instabilities persist after sufficient B, has been applied to Aremove the gross pinch instabilities. The conditions present in the tube will be compared with the stability criteria of B.R. SUYDAM. I

P/2396. The Effect of an Applied Pressure Gradient on a Magnetically Collimated Arc. R. V. NEIDIGH (U.S.A.). Some properties of a gaseous arc of special nature have been explored experimentally. The arc runs parallel to the lines of force in a uniform magnetic field. Gas is introduced near a hot cathode, and the arc runs toward a floating terminal electrode. When the pressure in the region of the main part of the column is reduced to the neighbourhood of 10-b mm Hg, the plasma and the potential distribution a short distance from the arc column are found to rotate about the arc column with a frequency of 25-50 kc, while in the region close to the column, rotation at a higher frequency takes place in the opposite direction. P/2410. Peaceful Uses of Fusion. TELLER(U.S.A.).


In order to release fusion energy in a controlled manner one has to bring hydrogen isotopes to exceedingly high temperatures. The problem is to contain this high-temperature ionized gas without excessive heat losses to the walls for a sufficient length of time. To accomplish this a magnetic field is used which forces the ionized particles of the gas to move in spirals. The difficulties of the technical execution include : the production of a sufficient quantity of gas at sufficiently high temperature, P/2395. Self-trapping of Magnetic Energy in a Stabilized Linear Discharge. L. C. BURKHARDT the cooling effects of impurities, and hydromagnetic instabilities. and R. H. LOVBERG(U.S.A.).

Abstracts and Titles The programme in the United States has developed along several lines : First there is the establishment of a closed annular current with magnetic lines of force encircling that current. This produces the well-known pinch effect. The second approach is called the stellarator. In this machine the field is essentially orthogonal to that in the pinch. It is produced by external coils. In order to accomplish better stability the two field systems described above are not used independently but rather each contains something of an admixture of the other one. The two approaches continue to differ, however, because the pinch experiment is pulsed whereas the stellarator experiment aims at a steady state. The third group of machines have open-ended fields which are, however, more intense at two places. These more intense fields constitute magnetic mirrors which reflect most of the spiraling ions. A fourth plan uses a system of circulating relativistic electrons pattern of magnetic

which establish a closed lines. The ionized gas is

then confined by this field. Difficulties so far have proved to be considerable, and we cannot predict a date at which power will be produced. Economic production of power will lie still farther in the future. We believe, however, that in the end it will be feasible. The eventual value of thermonuclear power is very great indeed. First of all, it will open up a practically limitless amount of energy. Furthermore the use of this energy is less hazardous than that of fission energy. Finally, direct conversion of part of this energy is feasible. The possibility also exists that fusion energy can be brought to an early practical use in a different way: by the controlled use of nuclear explosions.

for a Self-sustaining Steady State Thermonuclear Reaction. T. HESSELBERG


Some Criteria

JENSEN, 0. KOFOED-HANSEN, A. H. SILLESEN and C. F. WANDEL (Denmark). A thermonuclear reaction in an extended plasma is thought to be kept in a steady state by continuously adding cold deuterium and tritium and at the same time extracting part of the plasma. In general, it is necessary to reinject a fraction, E, of the power escaping from the plasma in form of electromagnetic radiation, kinetic energy of neutrons and heat in extracted

plasma. The fraction E turns out to be a function of the plasma temperature, the deuterium burn up and the tritium enrichment of the fuel only. It results that an optimum can be found for all three parameters. A few considerations are given of the extension of the theory to the problem of having different temperatures for the electrons and the different ions.


(ii) Reactor chemistry, physics technology papers


P/9. Empirical Laws for the Critical Masses of 23sU/348U Systems for a Range of Uranium Densities and Moderator Ratios. R. T. ACKROYD, H. W. HASKEY, D. KENYON and B. J. OWEN (United Kingdom).

P/10. Measurements of Reactor Spectra by Time-of-flight and Integral Methods. C. G. CAMPBELL, M. S. COATES, R. G. FREEMANTLE and M. J. POOLE (United Kingdom).

P/11. Some Fission Properties of Importance to Reactors. N. J. PATTENDEN (United Kingdom). P/13. Cross-section Measurements with Pile Neutron Spectrometers. S. J. COCKING and J. F. RAFFLE (United Kingdom).

The Use of the Pile Oscillator in Thermal Reactor Problems. H. ROSE, W. A. CARPER


and R. B. TATTERSALL (United


Review of Graphite Moderated Thermal Reactor Calculations. C. G. CAMPBELL B. CUTTS, I. A. MOSSOP and P. W. MUMMERY





P/16. Alhedo Methods. R. T. ACKROYD and J. D. MCCULLEN (United Kingdom).

Use of Analogue Wax Model Methods for Reactor Calculations. I. A. MOSSOP and


J. MCGHEE (United


The Calculation of Thermal Neutron Spectra. A. HASSI~, P. SCHOFIELD and


J. H. TAIT (United


The Calculations of Resonance Escape Probability by Monte Carlo Methods. K. W.


MORTON (United


P/20. Theoretical Methods for Fast Reactor Calculations. J. H. TAIT, M. F. JAMES, M. E. MANDL and J. S. STORY (United Kingdom). P/21. The Derivation Transient Equations Moderated Thermal (United Kingdom).

of Reactor Heat Transfer for Gas-cooled Graphite Reactors. T. J. O’NEILL

P/22. Research Reactor Utilization. F. W. FENNING, K. Q. BAGLEY and R. F. JACKSON (United Kingdom).

The use of DID0 for Neutron Beam Experiments. P. A. EGELSTAFF, N. J. PATTEN-



and J. F. RAFFLE (United


of Reactor Materials in Flowing Sodium. M. DAVIS and A. DRAYCO~T (United Kingdom).



The Effects of Neutron Irradiation on the Mechanical Properties of Graphite. H. W.


DAVIDSON and Kingdom).




LOSTY (United