Read a row on the benchmark and leaderboards

Every figure on this site is one measurement of one machine, with a status and a source. The benchmark lists them. The leaderboards rank the ones that can fairly be ranked.

Status

Each figure carries one status. The benchmark page groups figures by it.

• Achieved: measured on a shot (one run of the machine), with a date, and checked against the published source in a verification run.
• Claimed: reported by a source but not independently established. Most figures on the site are at this status. It means the source says so, not that the number is wrong.
• Planned: a target, design goal or roadmap date. It is shown, and never ranked.

Three more statuses exist and are not shown in the benchmark tables. Superseded means a later figure from the same machine beat it; the machine’s own page shows these under Progression, oldest first. Disputed means a credible challenge to the figure exists. Retracted means the figure has been withdrawn. Changes of status, with their reasons, are in the changelog.

A row on the benchmark

The benchmark has three tables: Achieved, Claimed and Planned. Each has the same six columns.

Device. The machine, linked to its own page. If the source gave a shot number, it appears in small type underneath.

Metric. What was measured, such as ion temperature or triple product. Hover over it, or move to it with the keyboard, to see the full name. For a ratio, the pop-up also shows what was divided by what. A word in brackets after the metric qualifies it: peak, sustained or nominal. A peak temperature lasted an instant, and is not the same figure as a sustained one.

Value. The number as recorded. Very large and very small numbers are written in scientific notation, so 80,000,000,000,000,000,000 appears as 8 × 10¹⁹. Hover over the value to see it written out in full.

Unit. The unit of that number. A ratio has no unit, so this cell is blank for a gain.

Date. When it was measured or stated. A dash means the source gave no date. We do not guess one.

Source. The first source for the figure, linked to the original publication.

Five quantities that describe a machine’s size and operating range (major radius, minor radius, plasma current, magnetic field and plasma duration) are left off the benchmark, including measured results for them. Their design values are listed on /devices/. Measured plasma durations, such as EAST’s 1,066 seconds, appear on the leaderboards and on each machine’s own page.

Denominators

Gain is energy out divided by energy in. The answer depends on what you count as “in”. The National Ignition Facility’s shot N221204 in December 2022 had a target gain of 1.5: fusion energy divided by the laser energy delivered to the target. Counted against the electricity the whole facility drew, the same shot was below 0.01.

So the site has no single “gain”. It has six forms, each with its numerator and denominator fixed in the record: target gain, capsule gain, plasma gain, equivalent gain, engineering gain and wall-plug gain. The Metric pop-up names the pair for each row. The gain page lists every gain figure with its form beside it. Compare two gains only if they are the same form.

A row on the leaderboards

Each leaderboard ranks one measured quantity where a higher value is better. A board is only shown when at least three devices have a figure. The columns are:

• #: rank.
• Device and Operator, each linked.
• Value: the figure converted into the board’s single unit, shown under the board’s heading. Ion temperature is reported in both kelvin and kiloelectronvolts (keV). One keV is about 11.6 million kelvin. Converting first stops a figure in keV being ranked against a larger-looking number in kelvin.
• As published: the figure in the source’s own unit, shown only when a conversion happened. Otherwise a dash.
• Status, with the date underneath.

Some figures are left off the leaderboards on purpose. Planned figures are excluded, and so are superseded, disputed and retracted ones. So are design parameters, which describe what a machine was built to do rather than what it did. Figures whose unit cannot be converted are excluded rather than ranked on a number that means something else. Each device appears once per board, at its best figure. Size measures such as major radius have no board at all, because a bigger machine is not a better one.

Following a figure to its source

1. On the benchmark, select the link in the Source column. It opens the original publication.
2. For the full list of sources behind a figure, open its device page, which lists every source with its independence label. How to check a source explains the labels.
3. The device page also shows each figure’s confidence, which says how far it has been checked. How we verify explains it.

The leaderboards and each machine’s own page do not show sources at present. Use the benchmark row or the CSV file.

Worked example

The Achieved table has a row for the National Ignition Facility, shot N221204. The metric reads Q_target. Its pop-up reads “Target gain (Q_target)” and divides the total fusion energy yield of the implosion by the laser energy delivered to the target, including hohlraum losses. The value is 1.5, with no unit, dated 2022-12-05. The Source link opens the peer-reviewed paper in Physical Review Letters. Its device page lists a second source, the laboratory’s own page, and label the paper independent and the laboratory page operator.

Sources

• Benchmark, Leaderboards, Gain, and Methodology on this site
• Abu-Shawareb et al., “Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment”, Physical Review Letters 132, 065102 (2024)