evolution of an off axis probe beam in emma
Download
Skip this Video
Download Presentation
Evolution of an off-axis probe beam in EMMA

Loading in 2 Seconds...

play fullscreen
1 / 8

Evolution of an off-axis probe beam in EMMA - PowerPoint PPT Presentation


  • 66 Views
  • Uploaded on

Evolution of an off-axis probe beam in EMMA. Shinji Machida ASTeC/STFC/RAL 29 April, 2008 http://www.astec.ac.uk/intbeams/users /machida/doc/nufact/ffag/machida20080429.pdf & ppt. Problem to be discussed (1) chromaticity. Nonscaling FFAG has finite chromaticity.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Evolution of an off-axis probe beam in EMMA' - conroy


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
evolution of an off axis probe beam in emma

Evolution of an off-axis probe beam in EMMA

Shinji Machida

ASTeC/STFC/RAL

29 April, 2008

http://www.astec.ac.uk/intbeams/users

/machida/doc/nufact/ffag/machida20080429.pdf & ppt

problem to be discussed 1 chromaticity
Problem to be discussed (1)chromaticity
  • Nonscaling FFAG has finite chromaticity.
  • There is no synchrotron oscillations.
  • Phase advance depends on momentum and its difference will be accumulated.
  • From the figure above, average chromaticity is roughly 10.
  • Take two particles with momentum difference of 1%, phase difference (/2) after 10 turns becomes 1.
problem to be discussed 2 what does that means
Problem to be discussed (2)what does that means?
  • As long as a beam is injected on-axis, the different phase advance is almost invisible.
  • Once a beam is injected off-axis, smearing in phase space should appear.
  • Phase difference of 2 after 10 turns means that a probe beam will be spread out completely in azimuthal direction.

y’

y’

dp>0

on-axis

off-axis

dp=0

dp<0

y

y

simulation results 1 momentum spread
Simulation results (1)momentum spread
  • Use the following parameters
    • a=1/6, b=1/4
    • Gaussian with a cut at 2 sigma
    • Acceleration with 10 turns

Figure shows dp/p of a few % during acceleration.

black: on-axis

red: off-axis in vertical with 1  mm rad (normalized)

simulation results 2 phase space evolution z pz
Simulation results (2)phase space evolution (z,pz)
  • A beam is initially displaced in vertical direction with 1  mm rad.
  • In 3 turns, a probe beam becomes a ring.
    • Chromaticity is large at low momentum.
simulation results 3 configuration space evolution s longitudinal z vertical
Simulation results (3)configuration space evolution (s-longitudinal,z-vertical)
  • A beam is initially displaced in vertical direction with 1  mm rad.
  • Correlation among longitudinal position, (momentum,) and vertical position is manifest.
simulation results 4 summary
Simulation results (4)summary
  • A probe beam injected off-axis quickly smears out and becomes a ring with a radius of the off-set amplitude.
  • This is a process which can not be restored at extraction.
impacts on emma design
Impacts on EMMA design
  • With a limited aperture only for a probe beam emittance, diagnostic line after extraction just sees a fraction of a probe beam.
    • We should design diagnostic line either
      • for only on-axis beam with tomography measurement, or
      • for off-axis large beam as well but give up tomography if it is hard to install.
  • We may not have to scan the whole phase space at injection. As long as the amplitude ( m rad) of the off-set is the same, probe beams end up with the same ring in phase space.
    • However, with machine errors, it is in fact difficult to know the amplitude at injection. It is useful to have some flexibilities to scan phase space.
    • We also need to show that a probe beam becomes a ring in the fastest acceleration case.
ad