Tajima, T. Civale, L. Schulze, R.K. JACoW Geneva, Switzerland 978-3-95450-178-6 10.18429/JACoW-SRF2015-TUPB053 English 700-702 TUPB053 SRF vacuum superconductivity status electron Contribution to a conference proceedings 2015 2015-12 http://dx.doi.org/10.18429/JACoW-SRF2015-TUPB053 http://srf2015.vrws.de/papers/tupb053.pdf This paper is focused on the development of MgB2 coating technique at LANL. Using boron film samples obtained at a large furnace system, we succeeded in obtaining superconducting MgB2 films (Tc of up to 37 K so far) by reacting them with Mg vapor. The major improvements were 1) confinement of the Mg vapor in a hot zone to mitigate the insufficient Mg pressure due to condensation on low temperature surfaces of the connected vacuum pipes and 2) reduction of cooldown time, i.e., ~13 minutes instead of ~1 day with the large system to prevent MgB2 from decomposing.