The Mach-2MHz M-E test article used two, Vishay/Ceramite 500pF at 15kV, Y5U high-k ceramic caps with an e-r = ~5,000 and a DF= ~2% at 1.0 kHz or a Q= 45 at 2.15 MHz where some of the data for the Mach-2MHz was taken which consistently demonstrated ~1.0 milli-Newton thrust signatures. As noted in my STAIF-2006 report, this test article also had an upper harmonic response of 3.8 MHz that demonstrated a first light thrust signature of +5.0 milli-Newton and -0.30 milli-Newton when the E- and B-fields were phased flipped 180 degrees, using a very well shielded and filetered 500 gram load cell for the thrust data. Cap voltage at these frequencies varied between 50 to 130 V-peak with B-field levels in the 20 to 45 Gauss range in the cap dielectric. Alas this test article also demonstrated thrust die off with time of operation which went to zero with about 15 minutes of cummlative run time.
Now my new MLT-2010 test article is using six, 390pF at 15kV, N4700 caps wired in series (62pF summation) that have an e-r = ~1,400 and a DF= 0.10% (Q= 1,000) or less at 100 kHz. Now here is the fun part, its Q at 2.0 MHz is ~500, but at 4.0 MHz it goes down to 140 which drastically affects its M-E scaling predictions. I’ll probably run this new unit at both frequencies to see how it responds at each.
My e-Bay procured HP-4275A LCR meter indicates that the capacitance of these N4700 caps goes UP at 2 & 4 MHz referenced to their 1.0 kHz values at low voltages, so even if they do go back down at a kV or so, (remember that I’m using 6-caps in series with about 500 to 1,500V-p over each cap dependent of freq.), it won’t be much of a change from the expected cap values. And besides I can calculate the actual operational capacitance value by noting the current going through this series connected L-C-R circuit and backing out the average capacitance value that way.
As to force measurments, my first go at it will be with the MLT test article and its 50 ohm Z-matching circuit mounted in a 32 oz Tin/steel Faraday shield/can that will be placed on a 0.1 gram resolution Acculab weight scale that I have in the lab. I’ll be driving it from my ICOM 746PRO HF Ham rig via an RG-316U coaxial cable. If someting of interests is expressed under those conditions, I’ll then go to the trouble of building up a battery powered 60W, one MOSFET HF transmitter module that I already have the parts for, mount it on the Faraday Shield with its battery, and repeat the above weight delta measurments. If I’m still observing a weight change under these conditions, then I’ll mount this MLT/Xmitter assembly on either a 2.0 meter pendulum that I have in the lab or if enough force is being produced, I’ll suspend this assembly from a fishscale and mount both of them in a vacuum bell Jar I have for degassing epoxies, and see if the weight differential is still expressed in a rough vacuum. Past that, send funding…