Black Start and Cold Start

Black start is the ability to bring power up from a fully de-energized state without help from the grid, a demanding requirement for any prime source.

Starting from nothing

A black start is the process of restoring a site or grid section from complete shutdown without drawing on an external supply. Most generators assume some external power to start; a black-start-capable source can bootstrap itself. For a sovereign site, black-start capability is what turns islanding from a bridge into a durable capability.

Fusion generators are demanding to start. A tandem-mirror burner requires energizing high-field magnets and establishing a plasma before it produces net output. Providing the bootstrap energy for that startup, and doing so from a de-energized state, is a real engineering requirement that any resilient deployment must solve.

Why this is honest to flag

Cold-start and black-start behavior for the burner is not demonstrated; it is a design consideration layered on top of the four physics gates. Stating it plainly is part of full-physics candor: a machine that cannot start without the grid is not grid-independent, regardless of its steady-state output.

• Black start = restore from full shutdown, no external supply
• It converts islanding into a durable capability
• Fusion startup needs bootstrap energy for magnets and plasma
• Cold-start behavior is undemonstrated at the design stage

Black-start capability is usually provided by a small, independent starting source, a battery bank or a compact generator, sized only to energize the prime source. For a fusion generator that starting source must supply magnet excitation and plasma initiation energy before any output exists. Designing and protecting that bootstrap chain is part of making the machine genuinely grid-independent rather than merely capable of steady-state operation once running.

This is a design-and-simulation consideration, not a delivered capability.