Vacuum technology - Introduction

Vacuum is the term commonly used to designate the state of a rarefied gas, or the atmosphere corresponding to a state in which the pressure is lower than that of the atmosphere. It's a vast field. While vacuum metallurgy, impregnation, drying, drying assisted or not by infrared radiation and microwaves, etc., can make do with a coarse or medium vacuum, vacuum coatings and semiconductor processing require a high vacuum. Research into surface phenomena and catalysis, nuclear physics and particle physics also require clean, ultra-high and even extreme vacuum.

As early as 1964, some laboratories achieved pressures of 10-12 Pa. Although this is a very low level, it is not yet the perfect vacuum.

To avoid contamination of space, the vacuum of space is only partially used. We only use antigravity. This is irrelevant to the articles in this section, which have been written with the aim of publicizing vacuum techniques that can be used on earth, and guiding engineers and technicians in their application.

Clearly, covering a scale extending to more than 15 powers of 10 requires different types of equipment, drawing on various fields of physics and chemistry. While today's equipment is increasingly powerful, it has not become any less demanding. On the contrary, the specific nature of today's applications has led to a proliferation of highly sophisticated equipment. The choice of pumping equipment, measurement and control equipment, and the materials used is of prime importance, and a good knowledge of vacuum science is essential. If you want to benefit from the progress made, you need to take precautions right from the design stage.

In order to cover all the areas of knowledge required by the vacuum technician, the section has been broken down into different articles. Readers will find a theoretical section, a description of equipment and everything they need to know about building enclosures. Application examples and a form are also given in the various treatises in the Techniques de l'Ingénieur collection.

Good technical and scientific knowledge is not enough to succeed in the vacuum business. Sound common sense and good reasoning skills are needed to be able to act successfully in the event of vicious breakdowns. And above all, three qualities are indispensable to anyone who wants to make a "good" vacuum:

• patience: pressure doesn't drop by a factor of 10 ⁴ let alone 10 ¹⁰ in a few minutes;

• cleanliness: a hair under a seal, a scratch or a fingerprint can compromise the success of an experiment;

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