Walter Wuensch is a principle applied physicist in the Radio-Frequency group at CERN currently leading the development of high-performance linac technology for multiple applications including CLIC and a broad range of next-generation compact accelerators including XFELs, Inverse Compton Sources and medical linacs. The accelerator technology development is complemented by both theoretical and experimental investigations of the fundamental processes which occur at high-gradients including field emission and breakdown. The investigations are illuminating long-standing mysteries and the newly gained understanding are being applied to a range of applications the electron linacs, RFQs and high-voltage systems.