Arc suppression coatings for electrodynamic tethers and spacecraft cabling

Advanced insulation materials are needed to support future electrodynamic tether missions as well as for other high voltage applications requiring direct exposure to vacuum/space plasma conditions, such as cabling to solar arrays. Some of the desired characteristics of these materials include the ability to resist damage from low-Earth-orbit environments (including atomic oxygen and micrometeoroids); insulating materials with high dielectric strengths and flexible enough to prevent damage; and conductors and coatings that have low electrical resistance. A particularly important concern is the need for electrical discharge/arc prevention and suppression if the electrical insulation is breached. In the case of discharges in a vacuum, the insulation material often becomes the gas source to feed the discharge. We have performed some preliminary work to identify, develop, and test these advanced coatings. The approach we are proposing for suppressing the discharge is including in the coating an encapsulated or entrapped electronegative gas, liquid, or solid that are released upon impact or at the onset of a discharge suppressing the growth and continuation of the discharge. This paper discusses the mechanisms for arc creation, preliminary tests we have preformed to suppress arc creation, and a path forward for development of such coatings.