Single cylinder-based rf-cavity-system types for correction cavities in a klystron-based Compact Linear Collider

The proposed pulse compression system for the klystron-based Compact Linear Collider (CLIC) is based on individual cavities that are defined as a storage cavity and several correction cavities. The correction cavities modulate the amplitudes of the input rf pulses, while the storage cavity compresses the modulated rf pulses and generates rf pulses with a high peak rf power. The essential requisites for the cavities are easy fabrication, optimal rf performance, and cost effectiveness. We have identified two novel rf-cavity-system types that can be used as correction cavities for klystron-based CLIC pulse compression systems, characterized by their compactness, advantageous large passband or low surface fields, and ease of fabrication. Both rf-cavity-system types adopt a cylindrical resonant cavity with <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msub><a:mrow><a:mi>TE</a:mi></a:mrow><a:mrow><a:mn>132</a:mn></a:mrow></a:msub></a:mrow></a:math> mode, employing four coupling holes to induce <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:msub><c:mrow><c:mi>TE</c:mi></c:mrow><c:mrow><c:mn>132</c:mn></c:mrow></c:msub></c:mrow></c:math> modes with dual polarizations. The power flow direction is facilitated by a U-shaped waveguide and a 3-dB hybrid in two layouts. A comprehensive discussion on the principles underlying these rf-cavity-system types is provided. In addition, we elucidate the rf designs of the individual cavities for principle demonstration. Furthermore, these two rf-cavity-system types can be readily adapted to other operational frequencies, such as C-band and S-band.