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FEL Beam Dynamics Group - Cavities (side view)
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Side view of the 9-cell cavity with the main power coupler port (right), the pick up probe (left),
and two higher-order mode (HOM) couplers.
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Parameters of the 9-cell cavity
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Type of accelerating structure
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Standing wave
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Accelerating mode
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TM010, π-mode
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Acc. gradient (104 active modules) at 20 GeV
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ƒRF [MHz]
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1300
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Nominal gradient
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Eacc [MV⁄m]
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23.6
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Quality factor
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Q0
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>1010
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Active length
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L [m]
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1.038
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Cell-to-cell coupling
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kcc [%]
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1.87
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Iris diameter
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[mm]
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70
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R⁄Q
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[Ω]
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1036
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Epeak ⁄ Eacc
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2.0
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Bpeak ⁄ Eacc
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[mT ⁄ MV⁄m]
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4.26
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Tuning range
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[kHz]
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±300
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Δƒ ⁄ ΔL
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[kHz ⁄ mm]
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35
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Lorentz force detuning constant
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KLor[Hz ⁄ (MV⁄m)2]
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1
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Qext of input coupler
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4.6 × 106
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Cavity bandwidth f ⁄ Qext
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[Hz] FWHM
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283
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Fill time
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[µs]
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780
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# of HOM couplers
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2
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(note: R = V2⁄P, where P is the dissipated power
and V the peak voltage in the equivalent LCR circuit)
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