Measurement of transverse emittances with a Solenoid (for GUN-0.1) - Jens Völker – (06.12.2011)
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Transcript of Measurement of transverse emittances with a Solenoid (for GUN-0.1) - Jens Völker – (06.12.2011)
Measurement of transverse emittances with a Solenoid
(for GUN-0.1)
- Jens Völker –(06.12.2011)
Technics and analysis for a Solenoid-Scan- Theory of a Solenoid-Scan- Simulation of the Solenoid
Measurements
Discussion
Emittancemeasurement with a solenoid-scan (Jens Völker)
Summary
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
SRF-GunSolenoid
Drive-Laser(λ=258nm) Pb-Cathode
Faraday-Cup / dump
YAG-screen(150µm thick)
Bending-Magnet
Schematic construction of the test facility
Emittancemeasurement with a solenoid-scan (Jens Völker)
Technics for a Solenoid-Scan
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
transverse beam width (rms) on screen:
β-function determined by Twiss-Matrix
L = Solenoid to ScreenLeff = effective length of the Solenoid
Emittancemeasurement with a solenoid-scan (Jens Völker) - SolenoidScan
Theory of a Solenoid-Scan
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
transverse beam width (rms) on screen:
β-function determined by Twiss-Matrix
φ<1 => expansion to first order
Emittancemeasurement with a solenoid-scan (Jens Völker) - SolenoidScan
Theory of a Solenoid-Scan
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
transverse beam width (rms) on screen:
β-function determined by Twiss-Matrix
Emittancemeasurement with a solenoid-scan (Jens Völker) - SolenoidScan
Theory of a Solenoid-Scan
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
transverse beam width (rms) on screen:
β-function determined by Twiss-Matrix
?
?
will be determined by simulations
Emittancemeasurement with a solenoid-scan (Jens Völker) - SolenoidScan
Theory of a Solenoid-Scan
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
1. step: calculations of the B-field in the Solenoidby Poisson-Superfish:
Beam-pipe
Coil-pack
Iron-yoke
Cu-cooling
µ-Shield
Emittancemeasurement with a solenoid-scan (Jens Völker) – Solenoid-Simulations
Simulation of the Solenoid
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
2. step: Integrate the 3d-fields into ASTRA
3. step: determine the transfer-matrix by special particle-distributions(parallel-particle-beam and particle-spotlights)
1. step: calculations of the B-field in the Solenoidby Poisson-Superfish:
Emittancemeasurement with a solenoid-scan (Jens Völker) – Solenoid-Simulations
Simulation of the Solenoid
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
Fit-solutions:
Emittancemeasurement with a solenoid-scan (Jens Völker) – Solenoid-Simulations
Simulation of the Solenoid
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
not emittance conserving
Emittancemeasurement with a solenoid-scan (Jens Völker) - Example
Analysis by using an example
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
Simulations of Soleonoid-Scans by ASTRA
min. bunch-width on Screen
Emittances increase behind the focus-point!
Emittancemeasurement with a solenoid-scan (Jens Völker) - Example
Analysis by using an example
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
not emittance conservinghigh-cut
Emittancemeasurement with a solenoid-scan (Jens Völker) - Example
Analysis by using an example
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
x (mm) y (mm)
x‘ (
mm
/m)
y‘ (
mm
/m)
Emittancemeasurement with a solenoid-scan (Jens Völker) - Example
Analysis by using an example
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
roughness of the cathode surface
bunch chargeshigher order effects:
- aberrations - displacements - asymmetries
All terms are generally correlated of each other and also depends on other effects (e.g. Shottky-effects)
Theory:
Emittancemeasurement with a solenoid-scan (Jens Völker) - Emittance
Measurements
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
emittances depends on :
• Laser spot size
• Laser intensity
• gradient of the electric field in Cavity and extraction phase of the bunch
Emittancemeasurement with a solenoid-scan (Jens Völker)
Measurements
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
Emittancemeasurement with a solenoid-scan (Jens Völker)
Measurements
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
Emittancemeasurement with a solenoid-scan (Jens Völker)
Measurements
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
Emittancemeasurement with a solenoid-scan (Jens Völker)
Measurements
εy
εx
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
What are the effects that dominate the emittance values?
by cathode surface Displacement of cavity and solenoid axis
Beam misalignment Asymetries of the E- or B-fields
electronscattering in thick screen
Emittancemeasurement with a solenoid-scan (Jens Völker)
Discussion
Emittance growth Uncertainties in Measurements
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
What are the effects that dominate the emittance values?
- Solenoid will be movable in the transvers space
for the next run:
Emittancemeasurement with a solenoid-scan (Jens Völker)
Discussion
by cathode surface Displacement of cavity and solenoid axis
Beam misalignment Asymetries of the E- or B-fields
electronscattering in thick screen
Emittance growth Uncertainties in Measurements
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
What are the effects that dominate the emittance values?
- Solenoid will be movable in the transverse space
- a small quadrupol will be installed behind the Solenoid
for the next run:
Emittancemeasurement with a solenoid-scan (Jens Völker)
Discussion
by cathode surface Displacement of cavity and solenoid axis
Beam misalignment Asymetries of the E- or B-fields
electronscattering in thick screen
Emittance growth Uncertainties in Measurements
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
What are the effects that dominate the emittance values?
- Solenoid will be movable in the transverse space
- a small quadrupol will be installed behind the Solenoid
for the next run:
- new screen-station (4 screens) with varying thickness an material + a wire-scanner
Emittancemeasurement with a solenoid-scan (Jens Völker)
Discussion
by cathode surface Displacement of cavity and solenoid axis
Beam misalignment Asymetries of the E- or B-fields
electronscattering in thick screen
Emittance growth Uncertainties in measurements
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
What are the effects that dominate the emittance values?
- Solenoid will be movable in the transverse space
- a small quadrupol will be installed behind the Solenoid
for the next run:
- new screen-station (4 screens) with varying thickness an material + a wire-scanner
- new methode for the measurement: slit-mask
Emittancemeasurement with a solenoid-scan (Jens Völker)
Discussion
by cathode surface Displacement of cavity and solenoid axis
Beam misalignment Asymetries of the E- or B-fields
electronscattering in thick screen
Emittance growth Uncertainties in measurements
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
Thank you for your attention.
Extras
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011
Extras
Emittance measurement with a solenoid-scan (Jens Völker) 06.12.2011