PRODUCTION OF A LOW-DENSITY FIELD-REVERSED CONFIGURATION PLASMA

The plasma density of a field reversed configuration (FRC) needs to be decreased below the present experimental regime in order to heat the plasma and sustain the configuration by a high energy neutral beam in an FRC reactor. However, as the plasma is produced in a linear vacuum vessel, there exists a severe breakdown limit at a low fill pressure a s compared with a toroidal system. A method to form FRCs beyond the br eakdown limit is proposed here. The preionized plasma is compressed by a strong bias field to enhance the plasma flow from the confinement r egion to the outside region and is then diluted before the start of th e confinement field on the NUCTE device. The use of a diluted plasma e nables the critical density of the FRC to be lowered from 1.1 x 10(21) to 5.6 x 10(20) m(-3) and the sum of the electron and ion temperature s to be increased from 0.35 to 0.81 keV.