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

80 5. RADIOFREQUENCY MEASUREMENT
perform transmission measurements to easily get resonant frequency
<strong>and</strong> quality factor 8 .
• AC Short-Circuit (SC) rod is able to short-circuit one AC cell.
• CC SC rod is able to short-circuit one CC cell.
In figure 5.8 the measurement on a stacked CC is shown. Four
metallic rods short-circuit the adjacent cavities to the one under measurement
<strong>and</strong> two pick-up rods makes the transmission coefficient measurement.
In figure 5.9 the same scheme is proposed for the accelerating
cavity. In figure 5.10 <strong>and</strong> 5.11 the measurement for the couplings are
shown. Note that we can use the rods as perturbing object in the
cavities.
Figure 5.8. Measurement on a stacked CC using the rods.
Figure 5.9. Measurement on a stacked AC using the rods.
4. Bead pulling measurement
In the construction of a linear accelerator the tolerance on the dimension
of mechanical pieces <strong>and</strong> some unavoidable construction errors
limit the ideal performances reachable in theory. This important fact
implies several errors in the relevant parameters of the single cavities,
8 Note that the quality factor in a brazed tank should be the design value <strong>and</strong>
its measurement has a low error.