These cross sections were measured by the process of passing a deuteron beam into a thin gas target contained behind a thin window of evaporated silicon monoxide. The energy loss in the window was measured by a deceleration technique. Charged particles from the reactions were observed at 90° in the laboratory system with proportional counters. Some results are as follows: for the reaction D(d,p)T, by use of the angular distribution reported by Wenzel and Whaling, the total cross section o-is 15.4 mb with a probable error of 3.2 percent at 100-kev incident deuteron energy; cr=0.629 mb±5 percent at 25 kev. For the reaction D(d,n)JIe z , o-=15.2 mb±3.2 percent at 100 kev;

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Experiments are reported on helical plasma equilibrium and stability in the Scyllac toroidal θ-pinch sectors (120°) which have major radii of 2.375 and 4.0 m with coil arc lengths of 5.0 and 8.4 m, respectively. In these experiments the outward toroidal drift force was compensated by a combination of ℓ = 1 helical and ℓ = 0 bumpy fields which are generated by shaping the inner surface of the compression coil or by driven ℓ = 1 windings. Time-resolved measurements were made of the gross plasma-column motion, the plasma radius, the magnetic flux excluded by the plasma, the external magnetic field, the plasma density, the electron and ion temperatures, and the plasma β at axial locations of minimum and maximum plasma radius. These data are used to study the approach to the theoretically predicted toroidal equilibrium (including axial pressure equilibrium). The plasma column remained in stable equilibrium for 7 – 10 μs in the 8-m sector compared with 4 – 7 μs in the 5-m experiment, at which times the onset of a terminating m = 1, k ≈ 0 sideways motion occurred. The results show that the plasma achieved axial pressure equilibrium (nkT = const) in 4 – 6 μs, while maintaining equilibrium in the toroidal plane for 10 μs or longer. The measurements of the plasma radius, β and magnetic field in the various experiments have confirmed in detail the stable toroidal equilibrium observed in the streak photographs during the first 4-10 μs of the discharge. The observed toroidal equilibria of the high-β, θ-pinch plasma are in quantitative agreement with MHD sharp-boundary theory and confirm the theoretical scaling of the equilibrium field between the 5-m and the 8-m sector experiments.

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A neutron-producing plasma with ion energy ∼3–4 keV has been produced at filling densities 10–50 μHg without negative bias magnetic fields in a 570-kJ theta pinch. Axial interferograms, taken with a ruby-laser-illuminated Mach—Zehnder interferometer show that a stable compressed plasma core exists throughout the magnetic half cycle with no ionized impurities outside the core, and no drift toward the wall. The interferograms give peak plasma densities of 2 to 5 × 1016 cm-3, and also indicate a loss of particles as a function of time. Plasma containment times (e-folding times of N) before peak compression are 6 to 30 μsec. The observed loss rates are approximately in agreement with predictions of free flow through an orifice whose radius is equal to an ion Larmor radius. Soft x-ray measurements yield ∼300 eV electron temperature for all filling pressures. Absolute intensities of the soft x-ray emissions show the impurity level to be <0.1%. The ion energy for the low-pressure regime deduced from pressure balance between plasma and magnetic field (assuming β = 1) is about a factor two higher than the ion energy deduced from the measured neutron yield for a Maxwell distribution. The discrepancy suggests that the distribution is more nearly monoenergetic than Maxwellian.