Noninierceptive Techniques for the Measurement of Longitudinal Parameiers for Intense H- Beams

With increasing brightness, beam diagnostic techniques requiring interception of the beam become impractical. For H- particle beams, solutions for this problem based on the phenomenon of photodissociation are currently under investigation at the Los Alamos National laboratory accelerator test stand (ATS). A laser can be used to selectively neutralize portions of the beam that can be characterized after the charged particles have been swept away. We have used this technique for the measurement of current density versus longitudinal phase and the longitudinal phasespace distribution at the output of the ATS radiofrequency quadrupole (RFQ). The results of our measurement are compared with the predictions of the particle-dynamics code, PARMIEQ.