Originally Posted by Matthew Cline
The reason why Mills has taken so long to find a commercially viable design comes down to how electrodynamics of plasma can be designed to support the hydrino reaction. It was only in late 2013 that Mills discovered that a characteristic of arc plasmas called Negative Differential Resistance
was an important pre-condition for sustaining the reaction. The hydrino reaction is ionizing, meaning that the HOH catalyst will ordinarily lose its outer electrons. This generates additional current in the plasma. If the plasma has a positive resistance, then increasing the current raises the voltage potential and therefore is unfavorable to the formation of subsequent hydrino reactions. However, if you create a NDR in the plasma (by supplying high current, in the neighborhood of 10k amps), then consider what happens to the voltage as the ionization-generated current is applied. Per Ohm's law, the increased current causes the voltage to drop! Instead of a negative feedback loop, there is now a positive feedback loop
supporting the formation of hydrinos. Under an NDR-containing arc plasma, the hydrino reaction becomes explosive. Before 2013/2014, none of Mills' designs could be commercialized because they were inherently rate limiting.
Since 2014, Mills' engineering efforts have been focused on containing and moderating arc plasma-based reactions involving low-voltage, high-current mixed with H2 gas fuel and trace amounts of HOH catalyst.