A heat engine that utilizes a controllable heat source that includes a body comprising a dopant that has an affinity for a fuel species, preferably a hydrogen isotope. The production of heat by the heat source can be modulated by the application of electric and/or magnetic fields to the body. The hear engine includes safety features that prevent excessive heat generation.

A heat engine that utilizes a controllable heat source that includes a body comprising a dopant that has an affinity for a fuel species, preferably a hydrogen isotope. The production of heat by the heat source can be modulated by the application of electric and/or magnetic fields to the body. The hear engine includes safety features that prevent excessive heat generation.

Examples of a plasma acceleration and compression device are described. The device includes a plasma accelerator with a high compression funnel section extending from an inlet of the accelerator and an elongated section connected to the high compression funnel section that can extend from the end of the funnel section to an accelerator's outlet. The funnel section can be a cone with a steep tapering while the elongated section can have a mild, gentle, tapering along its length toward the outlet. The device further includes a power source for providing a current pulse to the accelerator to generate a pushing flux to accelerate and compress a plasma torus throughout the accelerator. The current pulse can be so shaped so that the current pulse behind the plasma torus at the outlet of the elongated section is significantly smaller than the current pulse at the first end of the elongated section while the pressure of the plasma torus at the outlet of the elongated section is greater than the pressure of the plasma torus at the beginning of the elongated section.

Examples of a plasma acceleration and compression device are described. The device includes a plasma accelerator with a high compression funnel section extending from an inlet of the accelerator and an elongated section connected to the high compression funnel section that can extend from the end of the funnel section to an accelerator's outlet. The funnel section can be a cone with a steep tapering while the elongated section can have a mild, gentle, tapering along its length toward the outlet. The device further includes a power source for providing a current pulse to the accelerator to generate a pushing flux to accelerate and compress a plasma torus throughout the accelerator. The current pulse can be so shaped so that the current pulse behind the plasma torus at the outlet of the elongated section is significantly smaller than the current pulse at the first end of the elongated section while the pressure of the plasma torus at the outlet of the elongated section is greater than the pressure of the plasma torus at the beginning of the elongated section.