atf2 optics, tuning method and tolerances of initial alignment, magnets, power supplies etc
DESCRIPTION
ATF2 optics, tuning method and tolerances of initial alignment, magnets, power supplies etc. Andrei Seryi for the ATF2 optics design team. Optics Design of ATF2. ATF2 design & goals. Learn to achieve:. Beam. (A) Small beam size Obtain s y ~ 35nm Maintain for long time - PowerPoint PPT PresentationTRANSCRIPT
ATF2 optics … 1 3rd Mini-Workshop on Nano Project at ATF
ATF2 optics, tuning method and tolerances of initial
alignment, magnets, power supplies etc.
Andrei Seryi
for the ATF2 optics design team
ATF2 optics … 2 3rd Mini-Workshop on Nano Project at ATF
Optics Design of ATF2
Beam
ATF2 design & goals.Learn to achieve:(A) Small beam size
Obtain y ~ 35nmMaintain for long time
(B) Stabilization of beam center Down to < 2nm by nano-BPM Bunch-to-bunch feedback of
ILC-like train
PAC 05 paper:
ATF2 optics … 3 3rd Mini-Workshop on Nano Project at ATF
Emphasis on the optimal layout
New final focus
• Extend diagnostics section
ATF2 optics … 4 3rd Mini-Workshop on Nano Project at ATF
Emphasis on the optimal layout
ATF2 optics … 5 3rd Mini-Workshop on Nano Project at ATF
Optimal layout• Better optics• Allow extension of diagnostics section
– about 13m of additional space is possible
• Better location– Avoids many issue
• Give more suitable schedule for the international partners to find their contribution
ATF2 optics … 6 3rd Mini-Workshop on Nano Project at ATF
nBPMnBPM
FONT Compton / laserwireODR
ATF Extraction Line
Coupling Correction /Emittance Diagnostics
Coupling Correction and Emittance Diagnostics for the ATF2 Extraction Line, Mark Woodley• ideally
– correction section with 4 independent skew quadrupoles, followed by
– 2D (4 wire scanner) emittance measurement section– optics for orthogonal control of the 4 coupling phases– minimize εy once with each skew quadrupole
• in present ATF extraction line– non-optimal optics in EXT straight section– wire scanners and skew quads interspersed– each wire scanner has x, y, and “u/v” (small angle, ~10°)
wires
+ provide space for various experiments
ATF2 optics … 7 3rd Mini-Workshop on Nano Project at ATF
“Ideal” skew correction / ε diagnostic sectionSQ SQ SQ SQ
WS WS WS WS
90°90°
180°90°
90°90°
45°45°
45°45°
45°45°
– x– y
See http://www.slac.stanford.edu/cgi-wrap/getdoc/slac-pub-8581.pdf
ATF2 optics … 8 3rd Mini-Workshop on Nano Project at ATF
– x– y
5°8°
13°20°
30°36°
SQ SQ SQ SQ
WS WS WS WS WS
L = 11.43 m
Existing extraction line diagnostic section
ATF2 optics … 9 3rd Mini-Workshop on Nano Project at ATF
SQ SQ SQ SQ
L = 20.58 mΔL ≈ 10 m
WS WSWS WS WS
32°48°
51°21°
32°58°
58°32°
– x– y
1.1 1.11.3 1.10.9 0.9 0.9 0.7 1.31.2 1.2 1.7 1.7
σWS > 5 μ
“Ideal” skew correction / ε diagnostic section for ATF2Mark Woodley
ATF2 optics … 10 3rd Mini-Workshop on Nano Project at ATF
Tuning of ATF2 final focus• Procedure for ATF FF would be based on methods
implemented at SLC FFS and FFTB, developed further– beam-based alignment using, e.g., shunting method– verify first order optics with trajectories fits – fix the phase advance between sextupoles– set sextupoles to minimize chromaticity– use global tuning correctors (knobs) to tune both the first-
order and the nonlinear corrections using beam size measurements
• Extensive simulations of tuning for GLC/NLC and TESLA, but not always all possible sources of errors were included– e.g. position errors included but not field strength, or vice
versa
• Simulations of the ATF2 tuning procedure started by UK colleagues, James Jones et al.
ATF2 optics … 11 3rd Mini-Workshop on Nano Project at ATF
Tuning of NLC BDS, Yuri Nosochkov, Aug. 2002
Errors:
ATF2 optics … 12 3rd Mini-Workshop on Nano Project at ATF
Analysis of Multipole and Position Tolerances for the ATF2 Final Focus Line James Jones, ASTeC, Daresbury Laboratory• Analysed tolerances for all multipole components
up to 20pole -> will be used to optimize magnet designs
• Start analysis of position tolerances, including the effects of orbit correction and tuning knobs -> jitter and static position tolerances
ATF2 optics … 13 3rd Mini-Workshop on Nano Project at ATF
Field Tolerances – Individual Quads Multipole Errors
Skew
Normal
• Tolerance for 10% beam growth due to the multipole field in an individual magnet, in units of
• Multipoles from:– Order 10 (20 pole) : Red.. – Order 5 (10 pole): Light
Green..– Order 2 (Quad): Orange
n
n
n x
B
BK
1
ATF2 optics … 14 3rd Mini-Workshop on Nano Project at ATF
• Global tolerances are be determined considering the combined effect of all elements, including capabilities of correction methods
• The global tolerances will need to match the goals A and B of ATF2– 30% beam jitter for goal A and 10% (or a bit more?) beam size increase– for goal B, rely on intra-train feedback to reduce jitter, or aim to reduction of
beam jitter to ~5% by providing better stability?
2% Increase in beam size OR 2% change in position[beamsize] 2% Increase in beam size ONLY
Tol
eran
ce [m
-1]
Tol
eran
ce [m
-1]
Position Tolerances – effect of individual magnets
ATF2 optics … 15 3rd Mini-Workshop on Nano Project at ATF
Effect of all quads (jitter)• Look at the results without the final doublet as these
have the tightest tolerances – More likely to be specially mounted and aligned
• Quadrupoles only (2% change of IP position)– X-plane: 14.5nm– Y-plane: 0.87nm– Roll Angle: 6.9rad
• If we aim for 30%, this scales to ~12nm in verticalthe goal of 5% would corresponds to ~2nm– Feasibility of the latter, especially, need to be determined
ATF2 optics … 16 3rd Mini-Workshop on Nano Project at ATF
Position Tolerances with correction
• Assuming that the correction system will maintain the beam at the correct position, and looking only on beam size increase:– Quadrupoles only (2% increase)
• X-plane: 585 nm• Y-plane: 197 nm• Roll Angle: 1.48 rad
• Start developing tuning knobs (x, y, x waist , y waist ) and orbit correction and include them into procedure (no coupling correction yet)– Quadrupoles only (2% increase)
• X-plane: 16 m• Y-plane: 141 nm• Roll Angle: 3.5 rad
• Procedure, knobs, orbit corrections, is being further optimized final tolerances will be then determined
ATF2 optics … 17 3rd Mini-Workshop on Nano Project at ATF
“Strategy for Commissioning the Beam” chapter of ATF2 proposal Frank Zimmermann’s questionnaire and some answers
• Are all magnets on movers? yes• Are there dipole steering correctors? yes, several.
Optimal locations TBD• How many BPMs and are they tightly attached to
magnets attached to all quads, sextupoles and bends
• Are there beam loss monitors and current monitors (toroids)? Yes. Location?
• Are all magnets on individual power supplies? Yes. • Do we have conventional wire scanners and/or
screens/profile monitors? Yes. Locations and how many?
• What other existing diagnostics may be suitable for the commissioning?
• Does the various diagnostics, including BPMs, read out bunch by bunch or single bunch or integrated over a train?
ATF2 optics … 18 3rd Mini-Workshop on Nano Project at ATF
Other minor optics improvements needed• To make the design more construct-
able:– change bends from sector bends to
rectangular– use 0.8m bens (as used in ATF) instead
of 1m for better field stability and more space
– space near octupoles is too tight modify
– QM14 is the strongest quad, and is close to max field of BT quads reoptimize
ATF2 optics … 19 3rd Mini-Workshop on Nano Project at ATF
Summary• Between now and BDIR workshop the team
will concentrate on the optimal layout + extended diagnostics optics, continue development of the tuning methods and finalize the numbers for tolerances