It's probably #2. The paper, as presented at the 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, is available for purchase. I happened to have a spare $25 and a burning curiosity. The full paper isn't available on the NASA site, only the abstract can be gotten there for free. If you wanna read the details, you have to pay for 'em.
Anyhow, here's the relevant bit from the paper: "Two roughing pumps provide the vacuum required to lower the environment to approximately 10 Torr in less than 30 minutes. Then, two high-speed turbo pumps are used to complete the evacuation to 5x10E-6 Torr, which requires a few additional days. During this final evacuation, a large strip heater (mounted around most of the circumference of the cylindrical chamber) is used to heat the chamber interior sufficiently to emancipate volatile substances that typically coat the chamber interior walls whenever the chamber is at ambient pressure with the chamber door open. During test run data takes at vacuum, the turbo pumps continue to run to maintain the hard vacuum environment."
I'm not a physicist, but the paper is still an absolutely fascinating read, and contains a number of color photos of the test apparatus, the device itself, etc. The amount of detail they went into for the experiment is really impressive; seismically isolating the test chamber, using liquid metal (galinstan) electrical contacts to eliminate any forces due to a mechanical coupling to a wire, compensating for the magnetic field that is created by passing electricity through the device, and so on. This is NASA we're talking about here, the guys that do ROCKET SCIENCE. The idea that they wouldn't test this device in a vacuum is laughable.
Something spooky is going on inside this device, and I hope it doesn't take us too long to figure out what is really happening.