Theory, Design and Tests on a Prototype Module of a Compact ...

CHAPTER 3
<strong>Design</strong> Techniques for a Side Coupled Linac
This chapter deals with the techniques used to design the resonant
cavities <strong>and</strong> the other electromagnetic apparatus of a Side Coupled
Linac, the emphasis being on the particular case of LIBO.
A linear accelerator is composed by several systems, as shown in
figure 3.1, namely a particle source (or an injection system of the beam
coming from another accelerator), the resonant accelerating cavities
<strong>and</strong> the magnets for the focusing of the beam, the power klystron or
the radiofrequency power system, the vacuum pumps <strong>and</strong> the cooling
system.
Figure 3.1. Schematic view of a Linac.
The design of the so-called radiofrequency apparatus <strong>and</strong> of the
electromagnetic aspects of a Side Coupled Linac is not an automatic
procedure yet; the most part of the design is still a cut <strong>and</strong> paste procedure
where the experimental verification, namely the RF measurement,
plays the fundamental role.
By using a top-down approach, the design of such a structure can
be seen through different levels of detail, as shown in figure 3.2.
First, the accelerator is thought as a black box, where the particles
beam goes through. For this case, the parameters of interest are numerical
values, namely the entry <strong>and</strong> the output energy <strong>and</strong> velocity
of particles, the desired maximum length of the chain of cavities, the
transit time factor, the peak electric field <strong>and</strong> the feeding frequency.
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