Abstract: The effect of beam generated plasma in the channels of the ITER electrostatic residual ion dump (ERID) is investigated. The space charge due to the plasma and the separating positive and negative ion beams could cause the ERID to fail if the plasma density is sufficiently high. The gas density at which this occurs is derived for both the heating and diagnostic beam systems. For the heating beam system this critical density is a factor of 75 higher than the normal operational gas density , so no problems are anticipated. For the diagnostic beam , the critical density is only a factor of 3 higher and under certain circumstances could be exceeded.
