Beamline geometry and apertures

1
Dipole Beamline Simulation
Beamline geometry and apertures Safe point and
justification Methodology Parameter
sensitivity Assumptions and justifications Solutio
n Stress-testing Discussion of Control Measures
2
SPEAR Dipole Beamline

• More magnets than in ID case
• 4 sextupoles
• 12 sextupole pole failure scenarios to consider
• Complications / variations in the upstream
  straight (kickers, injected beam in BL1)

Lattice  SF A SD A QFC A
User 119.9433 151.1714 69.1316
Low ? 122.1299 156.2369 66.5435
Low ? 116.7965 154.2726 74.4722
3
Safe Point and Point Well Downstream of Injection
BEND
SD
SF
QFC
SF
SD
BEND
COR (off)
QD
Bending Magnet Beamline
COR
Intermediate Point
Stored Beam
PWDI
Safe Point
SEPTUM
BL1 is a special case Can treat the same but
include BTS apertures
BEND
K2
4
Relevant apertures and tolerances
108/-43 mm
59/-43 mm

• Tolerances for simulations
• 2mm for apertures inside SPEAR vacuum chamber
• 5 mm for Fixed Masks and lead shielding in the
  beamline
• Need more detailed analysis of the vertical
  extent of critical apertures

90/-43 mm
50/-43 mm
5
Backtracking Sequence
SPEAR Chamber (inner)
6
Backtracking Sequence
SPEAR Chamber (inner)
7
Backtracking Sequence
SPEAR Chamber (inner)
8
Backtracking Sequence
SPEAR Chamber (inner)
9
Backtracking Sequence
SPEAR Chamber (inner)
10
Backtracking Sequence
SPEAR Chamber (inner)
11
Backtracking Sequence
SPEAR Chamber (inner)
12
Backtracking Sequence
SPEAR Chamber (inner)
13
Backtracking Sequence
SPEAR Chamber (inner)
14
Backtracking Sequence
SPEAR Chamber (inner)
15
Backtracking Sequence
SPEAR Chamber (inner)
16
Backtracking Sequence
SPEAR Chamber (inner)
17
Backtracking Sequence
SPEAR Chamber (inner)
18
Backtracking Sequence
SPEAR Chamber (inner)
19
Backtracking Sequence
SPEAR Chamber (inner)
20
Backtracking from Safe Point
SPEAR Chamber (inner)
21
ABC safety argument
Safe Point in the Beamline
Point Well Downstream of Injection
Intermediate Point
Flip sign and compare to forward beam
SPEAR Chamber (inner)
22
Simulation range and the Worst Case
Parameter Range for Simulation
Injected Beam Energy -3 ... 10
Dipole -10 ... 10
QFC -10 ... 15
SF1, SF2 -10 ... 15
SD1, SD2 -10 ... 15
COR N 1,N 2 -3mrad 3mrad
QD (Upstream) -100 (Full short) 30
QF (Upstream) -30 ... 30
COR N 3 Off
23
Failure scenarios one at a time on top of Worst
Case

• Dipole Failure by -10
• Any single sextupole full short
• Both SF full short
• Both SD full short
• Any sextupole single pole short
• Any quadrupole single pole short
• QD full short
• QFC full short
• QF full short but unacceptable for ID beamlines

24
Stress test worst case against dipole failure
25
FOFB response to dipole failure, simulation in
present lattice (sp3v82)
COR Kick rad
COR Kick rad
Lower Orbit Interlock trip limit from 5 mm to 1.5
mm

• FOFB failure scenarios
• First corrector reaches limit, FOFB keeps going
• First corrector reaches limit, FOFB stops
• Unlimited corrector strength, Orbit Interlock
• 10 failure before stored beam is lost -
• safe assumption

COR Kick rad
26
Stress test worst case against QF shorts

• Single pole shorts OK
• Must protect against full QFC magnet or 2,3 pole
  shorts (wrench scenario)

27
Stress test worst case against sextupole failures

• Single pole shorts OK
• Must protect against full failure of SF string

28
Combine ID and Dipole beamline requirements in
the most restrictive way High-medium probability
change (tunable) parameters
Parameter Simulations Range Worst Case1 Control means
Injected Beam Energy -3 ... 10 -3 BTS energy filter Booster dipole current window
QF (Upstream) -30 ... 30 -30 Current / Voltage interlock. Possible backup integer tune crossing
QD (Upstream) -100 30 -100 PS limit. Possible backup integer tune crossing
QMS coils Included 5 May interlock 1 PS
QFC -10 ... 15 -10 Current / Voltage interlock
SF1, SF2 -10 ... 15 -10 Current / Voltage interlock
SD1, SD2 -10 ... 15 15 Current / Voltage interlock
COR N 1,N 2 -3mrad 3mrad 3mrad PS limit
Insertion Device and Trims -3mrad 3mrad 3mrad PS limits. ID design. Possible backup Orbit Interlock
COR N 3 Off2 Cables disconnected
1 We constructed Worst Case based on steepest
descent rather than global minima search. If
there is an even worse combination of tunable
parameters, full range simulations will find
it. 2 We found that setting N 2 and N 3
correctors to maximum value allowed by PS range
(3mrad) in combination with other failures, may
violate ABC in dipole beamlines. If we choose to
activate N 3 we would have to rerun dipole
beamlines with narrower limits an design controls.
29
Combine ID and Dipole beamline requirements in
the most restrictive way Low probability change
(failure) parameters
Parameter Control means
Dipole Stored Current Interlock Possible backup Orbit Interlock
QF single-pole, multi-pole, full shorts Current/Voltage Interlock Restricting access to Magnet connections Possible backup integer tune crossing
QD single-pole, multi-pole, full shorts Continuous range -100 30 No instant ABC violation. Control System Alarms. Possible backup integer tune crossing.
QFC single-pole, multi-pole, full short Current / Voltage interlock Restricting access to Magnet connections Possible Backup integer tune crossing
SF1, SF2 , SD1, SD2 single-pole, multi-pole, full short Current / Voltage Interlock Restricting access to Magnet connections Possible Backup integer tune crossing