Wu, A.D. Guo, H. He, Y. Hu, C.F. Huang, S.C. Li, C.L. Li, Y.M. Liu, X. Pan, F. Song, Y.K. Xiong, P.R. Yang, L. Yue, W.M. Zhang, C. Zhang, S.H. Zhao, H.W. JACoW Publishing Geneva, Switzerland 2226-0366 978-3-95450-194-6 10.18429/JACoW-LINAC2018-TUPO036 English 408-411 TUPO036 Contribution to a conference proceedings 2019 2019-01 https://doi.org/10.18429/JACoW-LINAC2018-TUPO036 http://jacow.org/linac2018/papers/tupo036.pdf Field emission occurred in SRF cavity is the major limitation to operate at high gradient with stability. The plasma in-situ cleaning for the low beta HWR cavity was carried out to remove the hydrocarbons contaminants on the inner cavity surface. And the vertical test results indicated that the field emission effect was relieved with the increasing of the quench point and emission set-on point. Thus, oxygen active plasma processing can be an effective method to solve the field emission issues for the low beta HWR cavity.