sps orbit stability: lhc injection quality and transfer lines
DESCRIPTION
SPS Orbit stability: LHC injection quality and transfer lines. Lene Drøsdal. LHC Injection quality. Injection quality is monitored by the IQC – main indictors of injection quality are: Beam losses Transfer line trajectories Injection oscillations (LHC trajectory first turn) - PowerPoint PPT PresentationTRANSCRIPT
Lene Drøsdal
SPS ORBIT STABILITY: LHC INJECTION QUALITY AND TRANSFER LINES
LIU SPS Orbit Correction Review 2
Injection quality is monitored by the IQC – main indictors of injection quality are:Beam lossesTransfer line trajectories Injection oscillations (LHC trajectory first turn)
Trajectory variations are mitigated by steering the transfer lines
Beam losses come from many sources: trajectory offsets, longitudinal distribution, transverse tail population...
LHC INJECTION QUALITY
16.1.2013
LIU SPS Orbit Correction Review 3
Two main effects of SPS orbit variations are seen at LHC injection:
SPS orbit variations at extraction cause trajectory variations in LHC and transfer linesVariations lead to frequent correction of transfer lines Sources identified by trajectory stability analysis
SPS tail scraping varies due to SPS orbit variations and need to be adjusted to maintain correct scraping
SPS ORBIT VARIATIONS
16.1.2013
ANALYSIS OF TRAJECTORY VARIATIONS
LIU SPS Orbit Correction Review 5
Over time the trajectories in the transfer lines are drifting and the lines need to be corrected
Corrections are done weekly to daily
By analysing uncorrected trajectories sources of variations can be investigated From YASP data the corrections are calculated and subtracted
from the trajectoriesThe resulting trajectories are analysed using MIA (Model
Independent Analysis)
TRANSFER LINE STABILITY
LIU SPS Orbit Correction Review 6
TI2 – Oct/Nov 2012 TI8 – Oct/Nov 2012
TRAJECTORY VARIATIONS
Horizontal plane: Variations of 3mm
Vertical plane: Variations of 1mm
16.1.2013
LIU SPS Orbit Correction Review 7
SOURCES OF VARIATION IFrom the difference
trajectories sources of variation can be identified using MIA to find the eigenmodes of variation
For both TI2 and TI8 there are2 strong sources in the horizontal
plane1-2 sources in the vertical planeThe sources are betatron
oscillations starting at the beginning of the line SPS
16.1.2013
LIU SPS Orbit Correction Review 8
By MAD-X simulations of possible errors the sources are identified:Horizontal plane:
SPS Orbit MSE (Extraction septum)
Vertical plane:SPS Orbit
Same sources match for TI2 and TI8
SOURCES OF VARIATION II
16.1.2013
Over a period of two weeks orbits were analysed by Hannes/Eliana
Measured orbit variations give trajectory variations around 1 mm
The resulting trajectory variations is a combination the two sources – for a longer time scale the Orbit contribution increase
SPS ORBIT VARIATIONS
TI2 variations ~5weeks TI2 variations ~1weeks
LIU SPS Orbit Correction Review 10
Current variations of the MSE has been identified as the main source of shot-by-shot trajectory variations
The size of the current variations do not grow significantly over time SPS orbit is the main source of trajectory drifts over time
MSE CURRENT VARIATIONS
MSE current variations ~3 weeks
16.1.2013
SPS TAIL SCRAPING
LIU SPS Orbit Correction Review 12
To minimize LHC injection losses from transverse tails the beam is scraped in the SPS before extraction
With no scraping losses are high enough to cause an LHC beam dump
1-2 % of the beam is scraped in each planeOver time the scraper settings need to be adjusted
to maintain correct scraping
SPS SCRAPING
16.1.2013
LIU SPS Orbit Correction Review 13
Before each fill the scraper settings are checked by the SPS crew
Every 2-3 fills the settings are adjusted
Takes a few minutesWithin each fill the
scraper settings are not changed and the amount scraped is stable
SCRAPER SETTING VARIATIONS
16.1.2013
LIU SPS Orbit Correction Review 14
In SPS MDs the beams were scanned to monitor beam variations at the scrapers
The measurements show that the changed in scraper settings follow the movement of the beam
During these tests the beam position changed by ~4mm in V and ~1mm in H
SPS ORBIT VARIATIONS
16.1.2013
15
The main effect of SPS orbit variations on injection quality is trajectory driftsBecause of trajectory drifts the transfer lines must be
corrected regularly The MSE also plays a role, but the variations are fast
Due to SPS orbit variations the scraper settings need to be adjusted to maintain correct scraping Setting need to be checked every fill, but acceptableDuring a fill the amount scraped remains stable
Other considerations Losses at TPSG (from extraction bump)?
SUMMARY
16.1.2013 LIU SPS Orbit Correction Review