Here is a picture of the test apparatus I set up to make some measurements of the FLAG output. You can see my electric field meter near the center which I bought off ebay many years ago (and I have great doubts about its calibration and accuracy). I have it mounted 1" from an aluminum plate which is charged by the FLAG, and is also connected to a large TDK UHV-2A ceramic capacitor so I can calculate the output current by seeing how long it takes to charge the capacitor with the FLAG while monitoring the voltage with the electric field meter. The electric field meter is connected to my multimeter, which is connected to my laptop with an optical connection so the data can be recorded on my computer without risk of accidentally exposing it to the high voltage output of the FLAG. The fieldmeter is a Prostat PFM-711A.