Transcript Mode 0 studies - Simulations

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
•
August 28th 2004
0 mode in LCLS injector gun
Cecile Limborg-Deprey
[email protected]
Ratio of 0mode amplitude to pi mode
August 28th 2004
0 mode in LCLS injector gun
Cecile Limborg-Deprey
[email protected]
Ratio of 0mode amplitude to pi mode
WRONG
RESONANCE
August 28th 2004
0 mode in LCLS injector gun
Cecile Limborg-Deprey
[email protected]
Ratio of 0mode amplitude to pi mode
August 28th 2004
0 mode in LCLS injector gun
Cecile Limborg-Deprey
[email protected]
Low Power pulse -
August 28th 2004
0 mode in LCLS injector gun
Cecile Limborg-Deprey
[email protected]
Ratio of 0mode amplitude to pi mode
WRONG
RESONANCE
August 28th 2004
0 mode in LCLS injector gun
Cecile Limborg-Deprey
[email protected]
Ratio of 0mode amplitude to pi mode
August 28th 2004
0 mode in LCLS injector gun
Cecile Limborg-Deprey
[email protected]
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?
August 28th 2004
0 mode in LCLS injector gun
Cecile Limborg-Deprey
[email protected]
SuperFish Map for PARMELA simulations
0 mode
August 28th 2004
0 mode in LCLS injector gun
Cecile Limborg-Deprey
[email protected]
PARMELA Simulations
with 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
August 28th 2004
0 mode in LCLS injector gun
Cecile Limborg-Deprey
[email protected]
PARMELA Simulations
with 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
August 28th 2004
0 mode in LCLS injector gun
Cecile Limborg-Deprey
[email protected]
PARMELA Simulations
with 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
August 28th 2004
0 mode in LCLS injector gun
Cecile Limborg-Deprey
[email protected]
Looking for better tuning when 0-mode is at  = 150
Injection phase does not help
Varying pi mode field amplitude helps
BUT
Nearly enough +
Sensitivity to field variation is increased
+
Difficulty to find 0-mode = 150
August 28th 2004
0 mode in LCLS injector gun
Cecile Limborg-Deprey
[email protected]
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;
August 28th 2004
0 mode in LCLS injector gun
3 s Klystron exciting the PI mode
Rs_0 = 4.71E+07 ;
Q0_0 = 13957;
Qext_0 = 6988;
f_0 = 2.856e9;
Cecile Limborg-Deprey
[email protected]