Abstract: An apparatus and a method is disclosed for in-situ deposition of thin films of high-temperature superconductor (HTS) compounds on a substrate that involves exposure of the substrate to a high pressure of oxygen and/or a high vapor pressure of volatile metallic elements such as Hg, Tl, Pb, Bi, K, Rb, etc., for stabilization of the crystal structure. Such compounds include basically all known HTS materials with Tc higher than 100 K. The method is based on pulsed laser deposition (PLD) and a cyclic (periodic) process, wherein the substrate is shuttled between a “closed” and an “open” position. In the “closed” position it is exposed to high temperature and high pressure of oxygen and/or volatile metallic species. In the “open” position, it is kept under low pressure and exposed to PLD plume. Short deposition bursts occur while the substrate is in the open position.