How long does plasma remain confined in inertial confinement fusion?

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3D illustration of the interior reaction chamber of a tokamak fusion reactor, showing a large, cylindrical, metallic structure with curved walls and bright light panels. — fusion reactor A tokamak is a device used in nuclear-fusion research for magnetic confinement of plasma.

In inertial confinement fusion (ICF), there is no attempt to hold the plasma in place using external fields. Instead, the plasma is confined only by its own inertia as it expands and disassembles.1

Because the plasma is not actively held, it remains confined for an extremely short duration, typically on the order of one nanosecond (one-billionth of a second). Some technical estimates for the minimum burn time can be as short as $20 \times 10^{- 12}$ seconds. In these systems, the fuel pellet must be compressed to high densities so that fusion power is produced during this brief window before the pellet blows apart.123