- Theory of Operation
The QDrive proof-of-concept (POC) superconducting resonating cavity is an experimental prototype designed to demonstrate the principle of unbalanced force generation. The POC cavity, experimental configuration, experimental method, and experimental results of the QDrive POC tests are described in this section of the website.
On Jan 13, 14, and 17, 2011, the QDrive POC experiment successfully demonstrated linear unbalanced force generation in a series of tests conducted at Niowave Inc. located in Lansing, MI. Niowave also built the POC cavity and the experimental apparatus.
Figures 1 and 2 depict two halves of the QDrive POC cavity. The dimensions are in cms.
Figure 1 depicts the top plate of the POC cavity. The top plate has two signal ports. Figure 2 depicts the bottom plate of the POC cavity. There are 72 identical slots cut in to the bottom plate. The slots have mill cuts in the side walls of the slots. Both halves of the cavity are made from a single cylinder of 250 RRR niobium. The two halves (top and bottom plate) are electron-beam welded together in the configuration depicted in Figure 3. Prior to the experimental tests of January 2011, two standard 3-acid chemical etches were applied to the cavity, removing approximately 100 microns of niobium per acid etching.
The POC cavity is designed to generate a linear imbalance in Lorentz force pressure on the cavity. The unbalanced-force vector developed by operating a TM010 EM wave in the POC cavity is coincident with the z-axis of Figure 3 and points in the positive z-direction.
Figure 4 depicts the cavity with attached signal cables and vacuum piping. The design of the vacuum piping allows for adjustments to the position of the power cable. The adjustable power coupling is required to allow for rapid burn-through of multipacting barriers, and to allow for positioning the power cable at or near unity coupling during experimental runs. The signal pickup cable is fixed in position. The power cable and signal pickup cable are used in a standard phase-lock loop circuit to power the cavity with up to 30 watts of forward power at the input signal port.
The POC cavity and attached vacuum tubing are only supported by the central vacuum pipe depicted in Figure 4. The central vacuum pipe is attached to a support arm depicted in Figure 4. During experimental runs, the cavity and attached vacuum tubes are supported by two Cooper Instruments LFS 210 load cells. The removable bellows of Figure 4 is removed from the experimental apparatus during testing. The two signal cables that are attached to the cavity are looped and supported above the experimental apparatus so that negligible vertical support is provided by the cables to the experimental apparatus.
During test runs, the cavity, vacuum tubing, and support arm are only supported by the 2 load cells beneath the support arm, and by the buoyancy of the cavity in the liquid helium bath. Signals from the two load cells are sent to a summing unit. The output of the summing unit is sent through a Cooper Instruments DCM 495 amplifier. The DCM amplifier output is routed through an Agilent 34110A 6 digit multimeter. The multimeter sends real-time signal output to a computer running Microsoft Excel. The output of the load cells is charted and recorded in real time. During experiments, the Excel file was projected onto a screen. All experimental runs, including the real time output of the load-cell circuit, were recorded on HD video.
Prior to test runs, the helium dewar depicted in Figure 4 is vacuum sealed. Pressure over the liquid helium is reduced to 50 Torre reducing its temperature to 2.3 K. Prior to experimental runs, the vacuum seal on the helium vessel is broken, bringing pressure above the liquid helium to atmospheric pressure. Tests on the cavity were then run while the liquid helium bath was below its atmospheric boiling temperature. The helium pump-down procedure eliminated boiling helium buoyancy beneath the cavity as a potential cause of false-positive experimental results.