_________________________________________________
G. Stupakov made few closing remark, he agreed upon the comment E. Schneidmiller did during the workshop. Specifically, E. Schneidmiller mentioned that writting dz/d(dp/p) as R56' was erroneous for linacs (while it is a correct statement for circular machine). G. Stupakov recognized that expliciting the R56 the right way render the Vaslov-Equation more intricate to solve (since it now incorporates some radial-depencies).
G. Stupakov says he will work toward a semi-analytic treatment of CSR that includes 2D effects. Such a model could then be coded into programs such as ELEGANT.
We must finish the benchmarking comparison (at the workshop time only M. Borland was able to run all the case), and agree on quantities to compare (on the web site, quantities mentioned turned out not to be so easy to compare).
The quantities are [defined a posteriori of the workshop]:
- emittance at end of beamline,
- accumulated longitudinal (and transverse when available) wake along
the beamline. [From this wake we can compute the energy loss and rms
energy spread solely induced via CSR self-interaction]
- beam envelope along the beamline,
- bunch phase space and distribution with and without CSR
Several group started simulation of microbunching, but the initial conditions were different (Borland modulates energy profile while Limberg/Piot and Dohlus started with modulated charge density). We decided to agree on the same starting point.
During the workshop, several groups presented the status of their experiments
aimed to study the impact of bunch compression on the beam dynamics.
To date CLIC (CERN), DUVFEL (Brookhaven), LEUTL (APS, Argonne) and TTF
(DESY-Hamburg) have taken some data. The CLIC, LEUTL and TTF teams have performed
some comparison with simulations which tend to indicate that the effects measured
are CSR-induced. DUVFEL and LEUTL have both ideal configuration for continuing
such investigations: LEUTL has a setup that enables the study of correlation
within x and dpp plane, DUVFEL has an extensive diagnostics suite that incorporates
a single shot measurement of the radiation spectrum emitted by the bunch.
|
ATF |
TTF |
LEUTL |
DUVFEL |
rho [m] |
1.2 |
1.6 |
0.8 |
0.8 |
theta [deg] |
20 |
18 |
13 |
13 |
R56 [m] |
0 - 0.1 |
0.18 - 0.21 |
0 - 0.065 |
0 - 0.1 |
E [MeV] |
70 |
140 |
150 |
70 |
Q [pC] |
500 |
4000 |
300 |
300 |
sin [mm] |
0.3@150pC |
2.7@1nC |
0.3@300pC |
0.24@300pC |
|
|
|
|
|
Lb [m] |
0.42 |
0.5 |
0.19 |
0.19 |
L1 [m] |
0.08 |
1 |
0.59 |
0.34 |
L2 [m] |
0.08 |
1.3 |
0.37 |
0.20 |
L3 [m] |
0.08 |
1 |
0.59 / 1.2 |
0.34 |
h [mm] |
15 |
15 / 8 |
40 |
15? |
Beam:
* transverse emittance, energy spread, beta, t-profile,
trajectory vs incoming chirp, Twiss functions,
* "Dowell" screen to see correlation between the chicane bending plane and the energy spread
* tomography
* what's about parametric study versus charge (only CLIC has done such
a study)
Radiation:
* power
* polarization,
* spectrum