Studies on a magnetron source

In working toward a less noisy H-. magnetron source, a new diagnostic tool consisting of a scannable Faraday Cup Array has been developed and installed on the Fermilab H-. ion source test bench. The array consists of 14 identical Faraday cups with I mm diameter entrance holes spaced 6.4 mm apart. H-. beam currents of 50 to 80 mA with a radius of roughly 3 to 4 cm at the collector are routinely produced by the magnetron. Local current density measurements made as a function of acceleration voltage, sample time during the pulse, and background pressure reveal space charge compensation and beam self-focusing. An optical means of measuring simultaneously the local current density and local phase space parameters is also being investigated. These measurements should shed further light on how the current and beam divergence is distributed over the beam cross section.