A PLASMA CONTAINMENT DEVICE ENTITLED ROMAC (ROTATED MAGNETIC CUSP) WASCONSTRUCTED. AN ATTEMPT WAS MADE TO COMBINE THE BASIC STABILITY ADVANTAGES OF FOUR-POLE LINE CUSP WITH THE LOW LOSS RATE OF A MORROR FIELD. THE MAGNETIC FIELD FOR ROMAC WAS PRODUCED BY ADDING A MIRROR FIELD ORTHONGONALLY TO THE CUSP FIELD. USING PULSE TECHNIQUES AN IONIZED GAS WAS CREATED WITHIN A BICONICAL CHAMBER AND THE ROMAC MAGNETIC FIELD PRODUCED TRANSIENTLY WITH THE MIRROR FIELD ALONG THE AXIS OF THE CHAMBER(Z AXIS) AND THE CUSP FIELD IN THE X-Y PLANE. MEASUREMENTS WITH MAGNETIC PROBES AND LIGHT PIPES SHOW THAT A DISTURBANCE IN THE MAGNETIC FIELD, ACCOMPANIED BY AN INCREASE IN LIGHT INTENSITY, STARTED AT THE PERIPHERY OF THE PLASMA CHAMBER AND WAS PROPAGATED INWARD AT TWO VELOCITIES TO THE CENTRAL AXIS. DETAILED MEASUREMENTS WERE MADE ON THE MAGNETIC FIELD CONFIGURATION. THESE INDICATE THAT, AT THE TIME THE SECOND WAVE ARRIVED AT THE AXIS, THE MIRROR HIELD HAD BEEN TO A LARGE EXTENT SEPARATED FROM THE CUSP FIELD SO THAT MOSTLY MIRROR FIELD EXISTED THROUGHOUT THE CENTRAL REGION, WHILE MOSTLY CUSP FIELD EXISTED IN THE OUTER REGION. THE INTENSITY OF THE FIELD AT THIS TIME IN THE CENTRAL REGION INDICATES THAT THE CUSP FIELD WAS COMPRESSING THE PLASMA AND MIRRORFIELD IN THIS REGION WERE EVEN LARGER THAN THE MAXIMUM INTENSITY OF THE APPLIED MIRROR FIELD.