Where the Wear is: Some Maintenance to Consider from the KIST 6 MV HVE Europa AMS System

Dr John A Eliades1, Dr Gwanho Lee1, Dr Byongyong  Yu1, Dr Joonkon Kim1, Mr. Weon Cheol Lim1, Mr.  Jaeyol Kim1, Dr. Jonghan Song1

1Korea Institute of Science and Technology, Seoul, Republic of (S.) Korea

This poster is primarily intended to aid others who run and maintain High Voltage Engineering Europa accelerator systems as these systems are now widely used. The KIST 6 MV system was installed in 2012 and commissioned in early 2013. While the system has run fairly well over the last ten years, there have been some problems that other users are likely to encounter after many hours of use. This will by no means be an exhaustive account. In each case, the system or component was inoperable until the problem was fixed. While the problems were not difficult to fix, identifying them took some time.

We have recently encountered problems with both of our SO110 ion sources. Firstly, the carousels have experienced sample loading failures due, at separate times, to the degradation of all of the potentiometers used to feedback carousel wheel position to the controller and also the brass rotation shaft assemblies used to actually rotate the carousel wheels. We replaced the potentiometers with equivalent but more robust units. The brass rotation shaft assemblies have been temporarily fixed by adjusting the rotation shaft locking position, but parts will likely need to be replaced in the near future. Secondly, we also experienced a vacuum leak at the Cs ionizer insulator cap. The leak was traced to a small crack at the thinnest section of this piece, where the bolts that hold the ionizer assembly to the insulator cap are screwed in place. This leak was sealed using a fairly cheap vacuum seal compound.

While most systems have probably been upgraded, we also experienced problems with Faraday cups that “fell off” of their insertion mounts. HVE has since changed the springs used to hold cups in position to a better, stainless steel material.

Our high voltage rf power supply has also suffered from false water cooling errors even though the cooling water quality and flow were fine. There is a “reed switch” unit inside the power supply, and after replacing this reed switch the system was able to be run normally. However, after four occurrences over the last five years, we are in the process of replacing this with a more robust flow meter.

We have also installed a monitor on the accelerator tank external motor used to turn the insulating shaft that is used to get power to the accelerator high voltage terminal. This is intended to detect wear on the rotation shaft as this is an expensive component to replace.


Biography:

I graduated from University of Toronto with a PhD in a joint physics and geology programme in 2021, studying at IsoTrace Laboratory. I then took a post-doctoral position with Korea Institute of Science and Technology in Korea, where I was hired as permanent research staff in 2013.

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Date

Nov 08 - 19 2021