Upgrade of CW negative hydrogen ion source

The CW surface-plasma source of H− ions was upgraded for increase the source lifetime and the high voltage holding. Basic improvements include the modification of magnetic system, the placement of anode collar between the dense discharge plasma region and the H− emission area, the increase of emission and ion-optical system aperture diameters and enforcing the power supplies to sustain the higher currents. Several long term runs with duration ∼1 hour each and negative ion beam current of 25 mA were performed. Direct measurements of H− beam profile and emittance were carried out by an electric sweep scanner. No saturation of the CW H− beam current with the discharge current increase was recorded.