Marcus Law, Joseph Brindley, Benoit Daniel , Gencoa Ltd, Liverpool, United Kingdom
Ensuring the integrity of vacuum systems prior to vacuum deposition and surface treatment processes is paramount, as even minor leaks can compromise the quality of coatings and lead to costly production downtimes. Conventional mass filter-based helium leak detectors offer high sensitivity and dominate the leak detection market making them the current industry standard. The tracer gas that makes these tools so powerful, Helium, can also be a major drawback due to ever increasing costs and uncertainty over long term supply. Leak checkers based on this technology are costly to produce and maintain and are frequently used where the level of sensitivity they offer is orders of magnitude higher than required.
In this contribution we report on a leak detection method based on an alternative gas sensing technology; remote plasma optical emission spectroscopy (RPOES). This technique leverages plasma-induced light emission to detect trace gases associated with leaks in real-time and offers detection and localisation with cheap, readily available gases such as Argon. It also offers greater robustness, an ability to operate at higher pressures and reduces maintenance requirements compared to traditional mass filter-based gas detection. We will discuss the principles of RPOES, its advantages in detecting specific gases commonly associated with leaks in vacuum systems (such as water vapor and air), and its viability as an alternative to traditional Helium methods. The advantages of the technique will be outlined, and we will present case studies demonstrating the effectiveness of this technology in identifying vacuum leaks in various coating applications, leading to improved process stability, enhanced coating quality, and reduced operational costs.