1. 20.9.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK Q ext estimations for the "Broad-Hook"-HOM coupler H.-W. Glock Universität Rostock - Institut für Allgemeine Elektrotechnik 20.9.2010

2. 2 "Classical" LEP hook design as starting point (priv.com. WW) 20.9.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock 2 coaxial 50-Ohm-port (connector not modelled) adjustable capacitive coupling combined E-/H-field coupling, capacity couples to outer conductor support carries liquid helium reminder

3. 3 20.9.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 3 E-field geometry @ 704 MHz strong capacitive coupling between "hook" and outer conductor capacitive coupling at hook determines notch resonance frequency reminder

4. 4 Pure hook not tunable for 704 MHz => Modification of hook end in order to adjust fundamental mode notch filter 20.9.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock 4 enlarge capacitive coupling at hook with additional surface element reminder

5. 5 20.9.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock 5 Waveguide(TM 0 )–Coax–Transmission blocked @ fundamental mode frequency => Tuning ok reminder

6. 6 20.9.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock 6 Q-ext estimations based on: CSC-coupling of 8 modes in D=130mm-coupler-cavity-connection (TE11,TM01, TE21,TM11,TE01) couplers left-right mirrored-symmetric (But: cavity asymmetric, no coupler calc for D=140mm-pipe up to now) D=80mm beam pipes left open (but most below cut-off)

7. 7 20.9.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock 7 This (cst-computation, csc-concatenation, q-fit-proc.) gives: Q_fundamental 3.0 10^8 much steeper Q(f) decrease than filter-free coax, BUT: still to high 1-1.5 GHz Is it possible to put coupler port closer to cavity waist (cav.design used from 21.7.2010)

8. 8 Our attempts to improve coupling 20.9.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock 8 23/02/2010 8 increase penetration depth: but poor effect, not nice for dark current flip hook to come closer to cavity: but total changeof filter behaviour, not tuned yet