Title: Contact resistance between two REBCO tapes under load and load-cycles,
Abstract: No-insulation (NI) REBCO magnets have many advantages. They are
self-protecting, therefore do not need quench detection and protection which
can be very challenging in a high Tc superconducting magnet. Moreover, by
removing insulation and allowing thinner copper stabilizer, NI REBCO magnets
have significantly higher engineering current density and higher mechanical
strength. On the other hand, NI REBCO magnets have drawbacks of long magnet
charging time and high field-ramp-loss. In principle, these drawbacks can be
mitigated by managing the turn-to-turn contact resistivity (Rc). Evidently the
first step toward managing Rc is to establish a reliable method of accurate Rc
measurement. In this paper, we present experimental Rc measurements of REBCO
tapes as a function of mechanical load up to 144 MPa and load cycles up to 14
times. We found that Rc is in the range of 26-100 uOhm-cm2; it decreases with
increasing pressure, and gradually increases with number of load cycles. The
results are discussed in the framework of Holm's electric contact theory.