[IEEE 2014 IEEE 41st International Conference on Plasma Sciences (ICOPS) held with 2014 IEEE International Conference on High-Power Particle Beams (BEAMS) - Washington, DC, USA (2014.5.25-2014.5.29)] 2014 IEEE 41st International Conference on Plasma Sciences (ICOPS) held with 2014 IEEE International Conference on High-Power Particle Beams (BEAMS) - Role of positive ions on the surface production of negative ions in a fusion plasma reactor type negative ion source—Insights from a 3D Particle-In-Cell Monte Carlo Collisions model