Pressure
Flow
Length
Area

Display only. Every formula on this site works in its own canonical unit, and the conversion happens where the number is written. The choice lives in this browser and in the address, with no account.

A luminous Gothic nave where shafts of golden light rise like the peaks of a mass spectrum, a single particle trajectory crossing the void.

Physical understanding is a fragile asset. Most organizations destroy it by accident.

Pierre F. Ribault · Vacuum science An industrial X-ray tube line. A synchrotron. A large accelerator. The same outgassing discipline runs through all three, each practising it on its own.

Mean Free Path

Essays, a sourced materials database, and design tools for ultra-high vacuum, written from the bench

Evidence

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A knurled steel punch lying beside a steel plate engraved 3e-12, the plate carrying the circular impression the punch has just left.

Sep 1, 2026 · under its source

A number is a claim

This site used to show outgassing values for 64 materials. It now shows 20, and the 44 removed had no traceable source.

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Materials

From surface to system

Three illustrative specimens with brushed stainless-steel, copper, and matte white ceramic surfaces.
Illustrative surface study. No grade, roughness, performance, or qualified combination is verified.

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The Matter

materials of ultra-high vacuum

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Gloved hands inspect a stainless-steel vacuum flange beneath a broad ring light.
Illustrative bench inspection. It documents no procedure and measures no surface condition.

Field practice

Field Notes

observations from the bench

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A lone figure looking across an illuminated mountain landscape beneath the Milky Way.

Open problems

The Frontier

open problems mapped

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Further reading

Selected essays

  1. Clean Has No Unit
  2. The Warhead Dividend
  3. The Banned Shelf
Complete essay archive →