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0 mode studies in LCLS injector gun C.Limborg-Deprey

0 mode studies in LCLS injector gun C.Limborg-Deprey. Frequency analysis of 0-Pi mode Determination of amplitude of 0 mode voltage from Frequency domain method PARMELA simulations. Ratio of 0mode amplitude to pi mode. Ratio of 0mode amplitude to pi mode. WRONG RESONANCE.

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0 mode studies in LCLS injector gun C.Limborg-Deprey

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  1. 0 mode studies in LCLS injector gunC.Limborg-Deprey • Frequency analysis of 0-Pi mode • Determination of amplitude of 0 mode voltage from Frequency domain method • PARMELA simulations

  2. Ratio of 0mode amplitude to pi mode

  3. Ratio of 0mode amplitude to pi mode WRONG RESONANCE

  4. Ratio of 0mode amplitude to pi mode

  5. Low Power pulse -

  6. Ratio of 0mode amplitude to pi mode WRONG RESONANCE

  7. Ratio of 0mode amplitude to pi mode

  8. PARMELA Simulations • Emittance Variation vs Amplitude in the 0 mode • For a 10MV/m amplitude in 0 mode, can there any beneficial effect of the 0 mode?

  9. SuperFish Map for PARMELA simulations0 mode

  10. PARMELA Simulationswith 0 and Pi modes Crude simulations With 5.5 k particles PARMELA Simulations even with 3 MV/m (magenta curve) in the 0 mode, there is some increase in emittance for half of the phases

  11. PARMELA Simulationswith 0 and Pi modes • PARMELA Simulations with 20k • particles • Half of the phases degrade the emittance, the other half improve it • at 2.852 GHz, a period is 0.5 degrees longer than at 2.856 GHz

  12. PARMELA Simulationswith 0 and Pi modes • PARMELA Simulations with 20k • Half of the phases degrade the emittance, the other half improve it • at 2.852 GHz, a period is 0.5 degrees longer than at 2.856 GHz

  13. Looking for better tuning when 0-mode is at  = 150 Varying pi mode field amplitude helps BUT Nearly enough + Sensitivity to field variation is increased + Difficulty to find 0-mode = 150 Injection phase does not help

  14. Time domain model 3 s Klystron exciting the 0 mode Rs_0 = 4.94E+06 ; Q0_0 = 12578; Qext_0 = 10000; f_0 = 2.8526e9; 3 s Klystron exciting the PI mode Rs_0 = 4.71E+07 ; Q0_0 = 13957; Qext_0 = 6988; f_0 = 2.856e9;

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