1：Experimental Design and Method Selection:

An improved reel-to-reel system with automatic flipping was designed for ion beam-assisted deposition (IBAD) and homo-epitaxy of MgO thin films on both sides of Hastelloy tapes.

2：Sample Selection and Data Sources:

75-μm-thick and 10-mm-wide flexible Hastelloy C276 tapes were used as substrates, processed with solution deposition planarization (SDP) technology to achieve smooth surfaces.

3：List of Experimental Equipment and Materials:

Equipment includes electron beam evaporation (EBE) for MgO deposition, Veeco RF ion source for Ar+ ion bombardment, re?ected high-energy electron diffraction (RHEED, Kimball Physics EGPS-6115) for real-time texture detection, X-ray diffractometer (XRD, Bede D1) for structural characterization, and atomic force microscope (AFM, Seiko SPM 300HV) for surface morphology analysis. Materials include Hastelloy tapes and MgO.

4：Experimental Procedures and Operational Workflow:

Tapes were moved through the deposition zone twice with automatic flipping; MgO was deposited via EBE under ion bombardment at specific parameters (e.g., Ar partial pressure of

5：2 × 10^-4 Pa, incident angle of 45°), with deposition rate controlled by thin film deposition controller (INFICON SQC-310). A mask was used to protect the back side during initial deposition. Data Analysis Methods:

XRD and AFM were used to analyze texture and surface morphology; RHEED patterns were categorized to identify texture types; process window was mapped based on deposition rate and ion beam flux.