Applied-B ion diode experiments on PBFA-I

The Applied-B diode has produced the highest brightness proton beam of any diode at the 1 TW and 3 TW power levels on the Proto-I[l] and Proto-II[2] accelerators. An experiment has begun on PBFA I to study the diode´s electrical coupling to the accelerator, ion conversion efficiency, and focusability of the proton component of the beam. The particular diode is a slightly larger version of a diode used successfully on Proto II. The diode radius has been increased from 14 cm to 15 cm, and the height from 5 cm to 6 cm, increasing the diode area from 440 cm² to 560 cm² to accomodate PBFA-I´s lower output impedance. Current neutralized beam propagation is provided by injecting the beam into a gas cell with a 2 µm mylar window a few mm from the AK gap, typically filled with 5 Torr argon. We will discuss the status of these experiments.