30 GHz rf components for CTF3 (and CLIC) next part. I. Syratchev

Transcription

1 3 GHz rf components for CTF3 (and CLIC) next part I. Syratchev

2 3 GHz overmoded waveguide components (GYCOM, Russia) Mode converter 4.86x5 Taper Mitered bend.75.5 T Measured losses per mode converter plus taper.5%.5 F F Time, ns F.5 F S, db S, db ).5 S, db S, db Measured losses per bend.% Time, ns

3 .75xTE +.5xTE. Max. electric filed at the mirror 8. MV/m (4 MW input power) Re (electric field) 9

4 3 GHz overmoded waveguide components (GYCOM, Russia) Waveguide trombone CTF3 7 m low RF loss transfer line Measured losses WG trombone.% Time, ns 3 S, db S, db F F Measured losses 4.5.%, reflection.% (long pulse) j) S, db S, db Time, ns Time, ns

5 3 GHz resonant delay line pulse compressor (GYCOM, Russia) 6 Power gain MW 5 MW CTF Power 3 MW CTF3 pulse length, ns The two lines were tuned to the frequency, using delay time measurement.

6 3 GHz resonant delay line pulse compressor (GYCOM, Russia) Reconstructed waveforms from the two lines measurements, losses were calibrated up to the yellow line 4 4 To the structure Power Pulse length, ns 3 4 To the load 4 6 Pulse length, ns Short circuit Main pumping station

7 New 3 GHz waveguide standard for CTF3/CLIC square 8.64x8.64 Pitting WR 34 PETS output flange view The picture of the PETS output waveguide have been made last year, when the best RF performance was 73 MW at 55 ns. Now we are about 9 MW and 8 ns. To reduce the surface field and to increase the vacuum conductivity, the new waveguide standard with square crass section was introduced. Special multipurpose 9 square waveguide bend E-polarization The number of waveguide components was designed and fabricated: 3dB hybrids Special multipurpose (E,H) 9 waveguide bends Directional couplers (see Alexej presentation) adapters and straight sections H > H mode converters (ordered from GYCOM) Waveguide components: adapter and straight section fully made of CuZr H-polarization S, db S, db

8 3 GHz High power attenuator (splitter). CLIC design. PETS() POLARIZER RF Load (3) S3,S4 Rectangular to circular Circular to elliptical S-parameters, db S S Elliptical With POLARIZER Rotation by 45 the RF power is efficiently switched between port and ports 3-4. RF Load () Accelerating Structure (4) S-parameters, db S S3,S4

9 3 GHz High power attenuator (splitter). Polarization selective RF splitter POLARIZER Elliptical waveguide section Choke junction in a circular waveguide (mode H) No electrical/mechanical contact is needed, if one uses chokes. Rectangular to circular taper

10 3 GHz High power attenuator (splitter). Scaled SLAC X-band version. In this RF circuit, the simultaneous shift of the two short circuits allows to split input power (port ) between two output ports port and port 3. Port Port3 H -> H mode converter Movable short circuits HFSS data S parameters, db Port Port Port 3 Port 4 3-dB hybrid Port Port 4

11 3 GHz High power attenuator (splitter). #. Ideal case Full geometry simulated H->H mode converter and tunable double piston short circuit. Position sensitivity analysis Ø.8. Port Port Port mode #. Diagonal offset..6 #. Tilt.5 Refl. Port Transm. Port(5 modes)

12 3 GHz High power attenuator (splitter). Low power test Measured losses 3.5% Full to the structure Full to the load

13 3 GHz High power attenuator (splitter). What have we learned during the high power operation:. A lot of vacuum activities associated with attenuator location have been observed. The certain processing period was needed at every new power level or the position of attenuator s pins.. For the first run, attenuation was limited to about 3dB due to the control settings. 3. It was changed to high values for the current run, but can be limited by vacuum activity. Temperature map on the pin surface for ns and 6 MW RF power, at the position of maximal attenuation. Pulsed heating T max ~ 3 C In general, the attenuator was very useful and made it possible the routine operation. However it was decided to built modified version, which is free now from the observed problems. IZNOGOOD!!!

14 3 GHz High power attenuator (splitter). Modified. Modifications: new square waveguide standard, doubled H -> H mode converter, two 4 mm pistons, vacuum port close to short circuit To be ready in march 6

15 Waveguide network in CTF test area as foreseen for the next run in 6. All the waveguide components have square cross-section RF/Vac. valve Straight Section (3 p.) HP load ( p.) Hybrid ( p.) H bend ( p.) E bend ( p.) Compressor Directional coupler (3 p.) WG taper (5 p.)