THE OHMIC HEATING OF A SPHEROMAK TO 100 EV

The first spheromaks with Thomson-scattering-measured electron temperatures of over 100 ev are described. The spheromak is generated by a magnetized coaxial plasma source in a background gas of 30 m Torr of H//2, and it is stably confined in an oblate 80 cm diam copper mesh flux conserver. The open mesh design allows rapid impurity transport out of the spheromak. The peak temperature, measured using multipoint Thomson scattering, is observed to rise from approximately 25 ev to over 100 ev in about 0. 2 msec due to Ohmic heating from the decaying magnetic fields. Density (approximately 5 multiplied by 10**1**3 cm** minus **3) and magnetic fields (approximately 2 kg) are measured using interferometry and magnetic probes.