The CERN Axion Solar Telescope (CAST) searches for $𝑎→𝛾$ conversion in the 9 T magnetic field of a refurbished LHC test magnet that can be directed toward the Sun. Two parallel magnet bores can be filled with helium of adjustable pressure to match the x-ray refractive mass $𝑚_𝛾$ to the axion search mass $𝑚_𝑎$. After the vacuum phase (2003–2004), which is optimal for $𝑚_𝑎≲0.02  eV$, we used $^4He$ in 2005–2007 to cover the mass range of 0.02–0.39 eV and $^3He$ in 2009–2011 to scan from 0.39 to 1.17 eV. After improving the detectors and shielding, we returned to 4He in 2012 to investigate a narrow $𝑚_𝑎$ range around 0.2 eV (“candidate setting” of our earlier search) and 0.39–0.42 eV, the upper axion mass range reachable with $^4He$, to “cross the axion line” for the KSVZ model. We have improved the limit on the axion-photon coupling to $𝑔_{𝑎⁢𝛾}<1.47×10^{−10}  GeV{−1}$ (95% C.L.), depending on the pressure settings. Since 2013, we have returned to the vacuum and aim for a significant increase in sensitivity.