Chin. Phys. B Vol. 26, No. 2 (2017) 025206New progress on beam availability and reliability of PKU highintensity CW proton ECR ion source ∗Shi-Xiang Peng(彭士香) 1,† , Ai-Lin Zhang(张艾霖) 1,2 , Hai-Tao Ren(任海涛) 1 , Yuan Xu(徐源) 1 ,Tao Zhang(张滔) 1 , Jing-Feng Zhang(张景丰) 1 , Jia-Mei Wen(温佳美) 1 ,Zhi-Yu Guo(郭之虞) 1 , and Jia-Er Chen(陈佳洱) 1,21 SKLNPT & IHIP, School of Physics, Peking University, Beijing 100871, China2 University of Chinese Academy of Sciences, Beijing 100049, China(Received 9 November 2016; revised manuscript received 15 December 2016; published online 10 January 2017)The stability and reliability of an ion source and its beam availability are extremely signif icant for any accelerator,especially for those high current long term CW operation ones like ADS. Although the f irst high quality 306-hours con-tinuous wave (CW) operating curve at 50 mA@35 keV has been successfully obtained with a standard compact 2.45 GHzECR ion source at Peking University (PKU), but the uncertainties that caused beam trips before are unacceptable duringan accelerator real operation and should be eliminated. Meanwhile, no permission will be given when the beam power isupgraded from 50 mA@35 keV to 50 mA@50 keV. To improve the PKU CW proton source quality, several upgrades weredone recently. After those improvements, a new long term CW proton beam experiment at 50 mA@50 keV was carriedout in June 2016. The total running time is 300.5 hours, including near 6 hours ion source preparation and 294 hoursnon-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 f l uctuations caused by the air conditionalfailure occurred. Beam availability and reliability within the 294 hours is 100%. The root-mean-square (RMS) emittanceof this 50 mA@50 keV CW proton beam is about 0.186 π.mm.mrad. A careful inspection of the ion source was done afterthis long term operation and no obvious damage was found. The restart experimental results obtained after the ion sourceinspection prove the high repeatability of PKU PMECRIS. In addition, a 130-mA H + beam was obtained at 50 kV withduty factor of 10% (100 Hz/1 ms) with this source. Details will be presented in this paper.Keywords: PKU PMECRIS, 50 mA@50 keV CW proton beam, 300-hours continuous operation, no beam-offPACS: 52.50.Sw, 52.50.Dg, 52.80.Pi, 52.59.–f DOI: 10.1088/1674-1056/26/2/0252061. IntroductionInterests on high-current high-power CW proton acceler-ator are increasing with the development of accelerator driventransmutation of nuclear waste [1] and other neutron sources.Elimination of beam trips, improving operational stability andreliability of the accelerators are more important issues thanever, especially for ADS. To meet the requirements of thoseaccelerators, high quality ion sources are extremely important.The 2.45-GHz microwave-driven ECR ion source that has theability to deliver tens-mA CW proton beam with unique char-acteristic of high stability, low emittance, operation reliabilityand longevity, is the best candidate for this kind of facilities. [2]To ensure the safety of the high-current high-power protonaccelerators, CW proton source should be carefully quali-f ied at each lab before they were used to deliver beams foraccelerators. [3,4] Before 2015, the longest uninterrupted runtime period of a CW 2.45-GHz ECR proton source in theworld was 103 hours at 95 keV with 75 mA kept by SILHIsource at CEA/Saclay France. [3]As a partner of CIADS project, PKU is undertaking theR & D program on high current CW hydrogen ion source de-velopment. A f ive-year plan (2014–2018) was proposed in theyear of 2013. Table 1 is the planned schedule.PKU compact permanent magnet 2.45-GHz ECR ionsources (PKU PMECRISs) have been demonstrated their re-liability to produce hundred mA proton beam in pulsed opera-tion mode with duty factor of 10%. [5] When we f irst started toproduce a 50-mA@35-keV CW proton beam with this kind ofECR ion source, sparks appeared frequently around the sourcebody and on the ion source test bench. Meanwhile, the faradaycup that was developed for pulsed beam measurement in thepass years was melted within 20 minutes. With some improve-ments described in Refs. [6] and [7], we were succeed to ob-tain a 306-hours continuous operation curve of 50 mA@35 kVCW proton beam at the beginning of 2015 on PKU ion sourcetest bench. During that 13-days running, neither sparks norplasma generator failure were observed. Five beam breaksthat caused by the failure of the water cooling machines wereencountered and some beam current drops and beam currentf l uctuations appeared. The longest uninterrupted run time wasabout 122 hours. The beam availability def ined as beam-on∗ Project supported by the National Basic Research Program of China (Grant No. 2014CB845502) and the National Natural Science Foundation of China (GrantNo. 11575013).† Corresponding author. E-mail: sxpeng@pku.edu.cn© 2017 Chinese Physical Society and IOP Publishing Ltd http://iopscience.iop.org/cpb http://cpb.iphy.ac.cn025206-1
