New collimator applications for post-LS1 operation - G. Valentino February 10th, 2014
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New collimator applications
for post-LS1 operation
Joint Collimation / Inj & Dump Meeting
February 10th, 2014
G. Valentino
with contributions from
S. Redaelli
Outline • Why do we need software upgrades? • Recap of SPS beam tests with BPM collimator prototype • Proposed software architecture • A first view of the top-level GUI • First thoughts on beam commissioning Joint controls meeting - 10/02/2014 G. Valentino - BE/ABP 2
Why do we need software upgrades?
To improve the present system based on last run’s experience:
• Merge both versions of lhc-app-collimators into single package.
• New handling of beam separation limits.
• Improved monitoring and setting verification tools (action from MPP workshop).
• Review of present settings generation framework under consideration.
Then, depending on status of ongoing work:
• Improved MP test sequence analysis (discussions initiated with K. Fuchsberger +
team).
• Analysis of post-mortem collimation buffer.
Joint controls meeting - 10/02/2014 G. Valentino - BE/ABP 3Why do we need software upgrades?
• During 2010-2013, all collimators were aligned with feedback from BLMs.
• Alignment procedure automated: feedback loop, pattern recognition of loss spikes,
BLM signal crosstalk.
Disadvantages of BLM-based alignment:
• Alignment time lengthy: even if reduced
from 30 hours to ~5 hours (Ph.D. work)
• Need to place setup error margins in the
settings (β* reach reduced)
• Setup errors could reduce cleaning
efficiency/compromise MP
• During post-LS1 operation, 18 collimators (20%) will be equipped with BPMs, 2
per jaw (up/down). Therefore, software is needed to:
1. Align the jaws with feedback from the BPMs.
2. Monitor the beam position within the collimator jaws
Joint controls meeting - 10/02/2014 G. Valentino - BE/ABP 4Recap of SPS beam tests
• BPM-based alignment algorithm needed due to BPM non-linearities.
• Otherwise, we would just need to move the jaws in or out in one step!
• 0.174
Algorithm seeks to minimize via successive approximation:
BPM Electrodes [arb. units]
0.173
0.172
0.171
0.170
0.169
BPM LU
Jaw furthest away from the beam moved in to:
0.168 BPM RU
0.167 BPM LD
BPM RD
0.166
0.2
Beam Center [mm]
0.1
0.0
-0.1
-0.2
-0.3
-0.4
Center UP
Center DW New: Individual jaw corners aligned!
30.0
Left Jaw Positions [mm]
29.9
29.8 Jaw LU
29.7
29.6
29.5
Jaw LD
Improvement by two orders of magnitude
over BLM-based alignment time!
29.4
29.3
29.2
-29.60
Right Jaw Positions [mm]
-29.65
-29.70
-29.75
-29.80 Jaw RU
-29.85 Jaw RD
-29.90
-29.95
-30.00
Algorithm + results published in IPAC13 and PRST-AB
0 5000 10000 15000 20000 25000 30000
Time [ms]
• Simulated non-linearity correction coefficients (A. Nosych) can be used
for monitoring purposes (or to speed up the alignment by a few seconds..).
Joint controls meeting - 10/02/2014 G. Valentino - BE/ABP 5Software architecture used in SPS
beam tests of BPM collimator
From this...
Joint controls meeting - 10/02/2014 G. Valentino - BE/ABP 6Proposed software architecture
for LHC
... to this UDP(12.5(Hz(
CBPM% JAWS%
CBPM% JAWS%
BLM%
s e d( System(
Propo
Exis6ng%
FESA%Class%
Logic/Server<
DOROS%
MeasuredCornerPosi6ons/LU% RequiredAbsolutePosi6on/LU%
MeasuredCornerPosi6ons/LD% RequiredAbsolutePosi6on/LD%
level(
MeasuredCornerPosi6ons/RU% RequiredAbsolutePosi6on/RU%
MeasuredCornerPosi6ons/RD% RequiredAbsolutePosi6on/RD%
Proposed(
CMW% 1(Hz(Subscribe( 8(Hz(Set( FESA(Class( TCP( UDP(
1(Hz( 25(Hz(
12.5%Hz%BLM%data% 1(Hz(Subscribe(
DOROS%
Collimator%Data%Concentrator%
Concentrator% Controller*%
Concentrator% 10(Hz(Subscrib
e(
BLM% BPM% Scan%
Alignment% Alignment% Algorithm%
UDP(25(
(
1(Hz(Subscribe( sc ribe
b
(Hz(Su
1
Proposed(
12(Hz(Subscribe(
FESA(Class( CMW%
Hz(
e(
(
ir b
et
(
c
z(S
cribe
bs e t(
1(Hz(Set(
1(H
u (S
z(S Hz
(
1(Hz(
(
Subs
.5
(H 8 OFC%
12
GUI/Top< Input% SIS%
level( Perform% Online%Monitoring% Perform% coefficients% Interlock% Logging%
Alignment% Display% Scan%
*conversion%of%integers%to%electrode%signals+beam%pos%(mm)%
Joint controls meeting - 10/02/2014 G. Valentino - BE/ABP 7First view of the top-level GUI
Alignment:
BLM (for reference only)
(similar to SPS tests)
will have possibility to Jaw positions
align all collimators
simultaneously
BPM electrodes
Relative beam position
Tilt
Absolute beam position
Monitoring:
(similar to current
Coll$Name$ Coll$Name$ Coll$Name$
collimator fixed display) ...
very preliminary view, 1σ# 1σ# 1σ#
circle turns red if 1σ Indication of
Coll#half#gap# Coll#half#gap# Coll#half#gap#
limit exceeded e.g.#9σ# e.g.#9σ# beam position e.g.#9σ#
Joint controls meeting - 10/02/2014 G. Valentino - BE/ABP 8Preliminary timeline
• Now: refactoring of collimator Java application (LSA API changes, merging of two SVN
branches of the application).
• Now: Functional specification for operation of BPM collimators.
• February: Design of Alignment and DOROS FESA classes.
• February (end): “LHCCollimators” FESA class v3 deployed (M. Donzé).
• March-May: Alignment & DOROS FESA class development.
• March: Standard tests with collimator test stand (function tests, FESA class tests).
• March-June: M. Gasior + J. Olexa (PhD student) FPGA BPM transmission.
• July: first wire tests of complete architecture with test stand.
• October: SPS beam tests with full software architecture + acquisition chain (to be
confirmed).
Joint controls meeting - 10/02/2014 G. Valentino - BE/ABP 9First thoughts on
beam commissioning of BPMs
• Caveat: advantages of BPMs cannot be exploited from Day 1 (unless enough
commissioning time is given), but should already profit from faster alignment.
• Need a staged beam commissioning plan / MDs to:
• measure the BPM non-linearity and electronics calibration coefficients for each collimator,
and compare to simulations;
• determine whether the alignments will still require dedicated fills for MP reasons, whether
they can be done automatically at the start of each fill, or whether small adjustments
can be permitted without opening the jaw position dump limits during physics;
• determine by how much the triplet-TCT-IR6 margins can be altered when re-centering the
jaws around the beam centre without causing risks for machine protection;
• incorporate beam position interlocks into SIS.
• Conservatively, we will not rely on the BPM functionality for the definition of the
first β* value baseline.
• Note: 80% of the collimation system is still without BPMs. Therefore, these
collimators will provide the commissioning baseline as in LHC Run 1.
Joint controls meeting - 10/02/2014 G. Valentino - BE/ABP 10Conclusions
• New collimators with BPMs will replace 20% of the current LHC collimators.
• Preparations for software to exploit the BPMs in the collimators are ongoing.
• The alignment FESA class will handle the alignment and act as a TCTP/TCSGP
data concentrator.
• The DOROS FESA class (developed by BI) will calculate the beam position based
on the received collimator and BPM data.
• GUI applications will allow for the alignment to be performed, and will provide
monitoring of the beam positions.
• Beam position interlocks (SIS) are
being considered, and will be implemented
as soon as we are confident of the reliability
of the BPMs.
• Functional spec document in preparation:
Joint controls meeting - 10/02/2014 G. Valentino - BE/ABP 11You can also read
