Biased electrodes for SOL control in NSTX

Abstract Small electrodes were installed in the outer-midplane edge of NSTX to attempt to control the local width of the scrape-off layer (SOL) by creating an outward E pol xB flow. When the applied voltage between electrodes was ±90 V, the density between these electrodes increased by a factor of 3–10 over a radial width of ∼4 cm. Thus a local control of the SOL plasma density was obtained.