A power supply consisting entirely of coaxial lines was used to produce a current pulse of 100 nsec duration in a thetatron coil, the plasma inside the coil being preionized. Measurements were made of the magnetic field, using magnetic probes, and of x rays produced. These measurements showed that, under suitable conditions, shock waves were produced and the electrons were heated to a temperature of several thousand electron volts. A necessary condition for producing an electron temperature approaching that required by shock theory was that the magnetic field outside the plasma should be in the opposite direction to the magnetic field inside the plasma.