Hasegawa, K. JACoW Publishing Geneva, Switzerland 2226-0366 978-3-95450-194-6 10.18429/JACoW-LINAC2018-THPO040 English 774-777 THPO040 linac operation DTL cavity target Contribution to a conference proceedings 2019 2019-01 https://doi.org/10.18429/JACoW-LINAC2018-THPO040 http://jacow.org/linac2018/papers/thpo040.pdf The J-PARC linac has delivered beam to users since 2008. As of 2018, the linac provides a 40 mA beam at an energy of 400 MeV to the following Rapid Cycling Synchrotron. We have had many issues to impede high availability during the operation. One of them was troubles of high voltage power supply of klystrons. The other category is related to vacuum property in accelerating cavities. The vacuum pumps were reinforced at the RFQ#1 in 2009. The cleaning of the inside surface of some acceleration cavities were performed after the big earthquake in 2011. The cooling water flow rate drop had been a long-time issue. We modified a cooling system to take better flow balances. As a result of these improvement, the availability is approximately 92% or more in these days. However, we have encountered another issue due to some aging components. The operation experiences and availability improvement at the J-PARC linac will be presented.