I had four things to do on my list:
- Use copper mesh to seal the small gaps around the top and bottom plates – After phoning metal supply places, arts and craft places, it turns out fine copper mesh is not easily sourced. The mesh pieces I had were too small, but I ordered more from a supplier on eBay and it should arrive by the middle of September.
I am also going to purchase the last few CF flanges I need for the vacuum chamber (not much of savings at 14 each considering they cost $15 each)
- The probe casing need to be properly grounded – There needs to be a clean high current path between the cavity and the probe casing which means those rolled copper shields around the conductor needs to be properly soldered to the cavity.Here is the measurement probe casing
Here is the power probe:However, the problem is the probe mount, which ideally should have a copper seat also soldered to the rolled copper, sort of shown below:
However, actually soldering the copper seat without melting the plastic and accidentally unsoldering the rolled copper shield is difficult. For now, I am going to make sure the rolled copper casing (which from the picture, I clearly have to redo given the humongous space, oops) presses up against the probe mount In the meantime, I have started to talk to local CNC shops to see if they can make me a probe mount from an easily-sourced standard 1.5″W by 1.5″L by 0.75″ H copper block. It will be sloped from top to bottom and also curved from left to right.
With those copper probe mounts, I will build a second cavity that will have a much cleaner probe hole and mount. The extra plastic top and bottom plastic rings will be used to hold on the end caps and it will also expose more of the cavity in order to see any hot spots building up.
- Thicker and better tuning plate – I created another tuning plate from the thicker copper sheet and it moves much more smoothly now, however, I was a bit overzealous in sanding and it is not exactly round
- Buy a Thermal Imaging Camera – I won the camera auction and used it around the house to learn a few interesting things:The temperature difference between a CFL and regular light bulb is considerable:
Which would explain why CFL’s are more efficient and last longer, because they don’t heat up nearly as much.
A few other interesting things:
The GTX 295 graphics card at idle (which, after I put a fan on it, now idles around 60 degrees C.)The images above show how the process of finding hot spots has changed from a hunt and peck with my year old Extech thermometer to an instantaneous “oh, how hot is that bright spot?” With a digital readout on the thermometer, it is really easy to miss what exactly is causing the smoke, but with the camera, you can watch the entire apparatus through 6400 pixels (80×80 resolution). The price difference is $70 versus $1700 though!
The thermal images will form an important test because a large number of mundane propulsion mechanisms can be tested for by showing where the cavity is and is not heating. Hot jets perhaps? Weird buoyancy effect from hot air? Twisting action of a hot cable? The thermal images will also be useful during testing to see if the cavity is in the right mode (hopefully by the pattern of hot spots) and to find early warning signs of problems.