the invention is embodied in a plasma reactor including a chamber enclosure having a process gas inlet and including a ceiling , a sidewall and a workpiece support pedestal capable of supporting a workpiece at a plasma processing location facing the ceiling , the workpiece processing location and ceiling defining a process region therebetween , the pedestal being spaced from said sidewall to define a pumping annulus therebetween having inner and outer walls , to permit process gas to be evacuated therethrough from the process region . the invention further includes a pair of opposing plasma confinement magnetic poles arranged adjacent the annulus within one of the inner and outer walls of the annulus , the opposing magnetic poles being axially displaced from one another the opposite poles being oriented to provide maximum magnetic flux in a direction across the annulus and a magnetic flux at the processing location less than the magnetic flux across the annulus .