Commissioning of vacuum pumping devices of the second KSTAR neutral beam injection system

•Efforts have been made to obtain high-quality vacuum condition for the KSTAR NBI.•The neutral beam injector requires the high vacuum pumping system which is capable of maintaining the vacuum pressure in the 10−5 mbar range during neutral beam pulses.•The detailed engineering design, fabrication, and installation results of large condensation cryo-pumps and vacuum sub-components were explained.•We present the commisioning results and status of the KSTAR NBI-2, and the concept design and operational characteristics of the vacuum pumping system on the KSTAR NBI-2.