HPEPL is most well-known for its two large vacuum test facilities, VTF-1 and VTF-2. The two test chambers can accomodated a diverse range of research experiments pertinent to the characterization of electric propulsion devices. Notable industry primes such as Lockheed-Martin and Moog have conducted test operations in VTF-1 and VTF-2 chambers. Furthermore, HPEPL's test facilities have also been critical in supporting developments in EP led by the Air Force Office of Scientific Research (AFOSR) and the Defense Advanced Research Projects Agency (DARPA). An extensive overview of both vacuum chambers is provided in this section along with the smaller Bell Jars and their capabilities.