8 Accelerator Engineering and Technology: Accelerator Technology
385
built for the test of the LHC crab cavities in the SPS for full validation in 2018, but
it is conceptually compatible with the LHC requirements.
8.3 Cryogenics
Ph. Lebrun · L. Tavian
8.3.1 Introduction
Cryogenics has become a key technology for particle accelerators, primarily as
ancillary to the developing use of superconducting magnets and RF cavities [44,
45]. In this class of applications, the superconductor must operate at a fraction
of its critical temperature in order to preserve current-carrying capability at high
field (magnets) or to limit a.c. losses (RF cavities), thus imposing the use of helium
in the case of low-temperature superconductors. Additional important benefits of
operating the accelerator beam pipes at low temperature are the achievement of
high vacuum through cryo-pumping of all residual gas species except helium, and
the reduction of wall resistance which controls image-current losses and transverse impedance. Following pioneering work at the TeVatron and first large-scale
applications (HERA, LEP2), accelerators at the energy frontier (RHIC, LHC) use
superconducting magnets, while high-intensity proton accelerators (SNS, ESS) and
high-energy electron linacs (European X-FEL, ILC) are based on superconducting
RF cavities, all requiring large helium cryogenic systems. A recent example of such
a system is sorely described in [46]. On a smaller scale, cryogenics is also at work
cooling compact superconducting cyclotrons for radionuclide production or particle
therapy, as well as compact synchrotron sources for X-ray lithography.
8.3.2 Cryogenic Fluids
8.3.2.1 Thermophysical Properties
The simplest way of cooling equipment with a cryogenic fluid is to make use of
its latent heat of vaporization, e.g. by immersion in a bath of boiling liquid. As
a consequence, the useful temperature range of cryogenic fluids [47–49] is that
in which there exists latent heat of vaporization, i.e. between the triple point and
the critical point, with a particular interest in the normal boiling point, i.e. the
saturation temperature at atmospheric pressure. This data are given in Table 8.8. In
the following, we will concentrate on two cryogens: helium which is the only liquid
at very low temperature and thus the coolant of low-temperature superconducting
385
built for the test of the LHC crab cavities in the SPS for full validation in 2018, but
it is conceptually compatible with the LHC requirements.
8.3 Cryogenics
Ph. Lebrun · L. Tavian
8.3.1 Introduction
Cryogenics has become a key technology for particle accelerators, primarily as
ancillary to the developing use of superconducting magnets and RF cavities [44,
45]. In this class of applications, the superconductor must operate at a fraction
of its critical temperature in order to preserve current-carrying capability at high
field (magnets) or to limit a.c. losses (RF cavities), thus imposing the use of helium
in the case of low-temperature superconductors. Additional important benefits of
operating the accelerator beam pipes at low temperature are the achievement of
high vacuum through cryo-pumping of all residual gas species except helium, and
the reduction of wall resistance which controls image-current losses and transverse impedance. Following pioneering work at the TeVatron and first large-scale
applications (HERA, LEP2), accelerators at the energy frontier (RHIC, LHC) use
superconducting magnets, while high-intensity proton accelerators (SNS, ESS) and
high-energy electron linacs (European X-FEL, ILC) are based on superconducting
RF cavities, all requiring large helium cryogenic systems. A recent example of such
a system is sorely described in [46]. On a smaller scale, cryogenics is also at work
cooling compact superconducting cyclotrons for radionuclide production or particle
therapy, as well as compact synchrotron sources for X-ray lithography.
8.3.2 Cryogenic Fluids
8.3.2.1 Thermophysical Properties
The simplest way of cooling equipment with a cryogenic fluid is to make use of
its latent heat of vaporization, e.g. by immersion in a bath of boiling liquid. As
a consequence, the useful temperature range of cryogenic fluids [47–49] is that
in which there exists latent heat of vaporization, i.e. between the triple point and
the critical point, with a particular interest in the normal boiling point, i.e. the
saturation temperature at atmospheric pressure. This data are given in Table 8.8. In
the following, we will concentrate on two cryogens: helium which is the only liquid
at very low temperature and thus the coolant of low-temperature superconducting