HIGH CURRENT ION SOURCES, BEAM DIAGNOSTICS AND EMITTANCE MEASUREMENT

Singly charged ion sources can easily surpass the 1 kW beam power, as in TRIPS (H, 60 mA, 80 kV, now installed at LNL) or in NIO1 (H−, 130 mA distributed into 9 beamlets, 60 kV, a project of RFX and INFN-LNL). Beam diagnostic constitutes an important instrument in the high current source development. Even if calorimetric and optical beam profile monitors become possible, still a phase space plot of the beam will be the most useful tool for validation of extraction simulation and for input of subsequent beam transport optimization. Improvements in extraction beam simulations are briefly reported, and effect of space charge neutralization is discussed. Since preliminary design of the traditional two moving slit beam emittance meter show problems with slit deformations and tolerances and with secondary emission, an Allison scanner was chosen with the advantages: only one movement is needed; data acquisition is serial and signal can have an adequate suppression of secondary electrons. The design of a compact Allison scanner head is discussed in detail, showing : 1) the parameter optimization; 2) the segmented construction of electrodes. Experimental commissioning at lower power seems advisable.