New progress on beam availability and reliability of PKU high intensity CW proton ECR ion source

The stability and reliability of an ion source and its beam availability are extremely significant for any accelerator, especially for those high current long term CW operation ones like ADS. Although the first high quality 306-hours continuous wave (CW) operating curve at 50 mA@35 keV has been successfully obtained with a standard compact 2.45 GHz ECR ion source at Peking University (PKU), but the uncertainties that caused beam trips before are unacceptable during an accelerator real operation and should be eliminated. Meanwhile, no permission will be given when the beam power is upgraded from 50 mA@35 keV to 50 mA@50 keV. To improve the PKU CW proton source quality, several upgrades were done recently. After those improvements, a new long term CW proton beam experiment at 50 mA@50 keV was carried out in June 2016. The total running time is 300.5 hours, including near 6 hours ion source preparation and 294 hours non-disturb continuous operation. Within the continuous 13 days operation, no beam-off happened, no spark was observed, no beam drop appeared, no interrupting action was needed, and only a few beam fluctuations caused by the air conditional failure occurred. Beam availability and reliability within the 294 hours is 100%. The root-mean-square (RMS) emittance of this 50 mA@50 keV CW proton beam is about 0.186 π.mm.mrad. A careful inspection of the ion source was done after this long term operation and no obvious damage was found. The restart experimental results obtained after the ion source inspection prove the high repeatability of PKU PMECRIS. In addition, a 130-mA H⁺ beam was obtained at 50 kV with duty factor of 10% (100 Hz/1 ms) with this source. Details will be presented in this paper.