The original speed demonstrator is pictured at left in its test fixture. Its sole task was to show higher speed to replace the slower solenoid used to operate a conventional fuel injector servo-valve. This device was an actuator only, a test of the speed theory found in U.S. Patent 7,255,290. The rod expanded against 20,000 psi fuel used to preload it through an area ratio.

Test results are graphed on the right. The upper plot expands the first 10% of the data plotted below. Both expansion and speed significantly exceeded the original target prediction of 70 micrometers in 100 microseconds, achieving 100 micrometers in 89 microseconds. SAE paper 2011-01-0381 is the test report.

The expansion is especially significant since it peaked at about three times the predicted amount. The 200+ micrometer expansion can completely uncover a typical injector nozzle of 200 micrometers in diameter. This data made clear that the traditional, conventional servo-valve and solenoid could be eliminated; direct needle drive is possible.

The test strategy of using a squared-off open-loop voltage input pulse (yellow trace) caused the ringing in both the current (magenta trace) and rod expansion (green trace) curves. This voltage profile had the desired effect of quickly spinning up, maintaining, and spinning down the electron sheet surrounding the rod.

• To avoid any failure, voltage was limited to +/- 100 volts.
  
  
• There were no internal stops in the range of motion.

Unacceptable for directly positioning the needle of a diesel injector both quickly and precisely, the plainly visible ringing launched development of the "Bright Principle" control method.