The design and performance of Zeta

The paper describes the main design parameters of the pinched-ring discharge apparatus Zeta, the principal observations made with it during the period up to April, 1958, and the deductions on the physical phenomena occurring in the hot gas. Discharge pulses of up to 200 kA have been passed through deuterium. The pinched current channel has a resistance of about 3 milliohms and an inductance of about 4 μH. The power input corresponds to the magnetically confined gas losing its kinetic thermal energy every 100 microsec. Energies of tracer impurity ions measured spectroscopically correspond to temperatures of 5×106deg K. Electron temperatures estimated from the resistance, microwave noise and spectroscopic intensities are in the range 1–5×105deg K. The greater temperature of the ions could be due to macroscopic motion of the gas.