Transcript T. Smith

LER BBA Quad Shunt Project
Dec. 14, 2004
PEP-II MAC
Tonee Smith, ILC
Marc Ross
Doug McCormick
Justin May
Janice Nelson
Jerry Yocky
Nicole Varela
Juan Cruz
Tonee Smith
1
LER BBA Retrospective
• Last fall a BBA program was initiated in both PEP-II
rings as part of a larger effort to further understand
the BPM performance.
– HER results were successfully implemented, and served
to validate the BBA procedure.
– LER results have also been implemented, but not fully
utilized.
• Reanalysis of results with fully coupled algorithm was needed.
• IR2 results (the most important) have been limited by lack of
independent quadrupole control
Dec. 14, 2004
PEP-II MAC
Tonee Smith, ILC
2
LER BBA: Program goals
• To find the magnetic center of quadrupoles at optically
sensitive locations in the ring. Shunts are used to vary the
field in one magnet which otherwise lacks individual
control.
• In IR2, there are four strings powering a total of 14 quads:
QFCY1 (4), QDCY2 (4), QFCX3 (2), QDCX2 (4)
• Throughout the ring there are 37 individual QD and QF
(tune) quads which have been identified as prime candidates
for BBA.
– These are in the arcs, immediately adjacent to sextupoles
– There are 2-5 quads per half-arc
Dec. 14, 2004
PEP-II MAC
Tonee Smith, ILC
3
LER BBA: Quad Shunt History
• In 1995, switchable shunt resistor circuits were installed on
each quadrupole in the SPEAR ring to facilitate beam-based
alignment. They were used with great success.
• These shunts were removed as part of the SPEAR3 upgrade,
and the hardware was sent to Salvage.
• The shunts were moved to B15 and proposals were made to
upgrade them for use in PEP-II (all ultimately deemed too
costly) .
• The shunts were taken as is to NLCTA, cleaned up, and
tested on a LER Quad in Magnetic Measurements. 42/45
were found to be fully functional.
Dec. 14, 2004
PEP-II MAC
Tonee Smith, ILC
4
LER BBA: Quad shunt hardware
The shunts consist of
two high-power
(250W) resistors
in parallel on a 1”
copper heat sink,
controlled by an
IDOM-driven
FET switch.
Dec. 14, 2004
PEP-II MAC
Tonee Smith, ILC
5
LER BBA: Shunt Hardware details
• Water cooling unnecessary for our application (resistors
operating at ~15% rated power on a large thermal mass).
– We have tested at 150% expected operating power for ~1 hour. Max
temperature reached was 55ºC without water cooling.
• Design is simple yet robust, with a low mortality rate even
after months outside in Salvage.
• Minor control board modifications (snubber circuit) were
made to protect the FET switches at our operating values.
• No-frills controls (+24V, on/off, and minimally-calibrated
analog read back of shunt current) allowed for a
straightforward cable plant.
Dec. 14, 2004
PEP-II MAC
Tonee Smith, ILC
6
LER BBA: Quad shunt installation
•We currently have 18 shunts installed on individual QD and QF magnets
throughout the ring.
•High power resistor values 0.45 W and 0.55 W will shunt ~3% of an individual QD or
QF magnet’s current
•These have been checked out on the bench (dummy load and test
stand magnet) and in the field (SCP control) and are ready for BBA
when PEP turns on next year.
String
Magnet R
Mag I
Mag V
Shunt V
Shunt R
Shunt I
Shunt %
Shunt P
QD(18)
0.019
300
5.7
4.2
0.45
9.3
3.11
39.2
0.019
300
5.7
4.2
0.55
7.6
2.55
32.1
0.019
300
5.7
4.2
0.45
9.3
3.11
39.2
0.019
300
5.7
4.2
0.55
7.6
2.55
32.1
QF(19)
Dec. 14, 2004
PEP-II MAC
Tonee Smith, ILC
7
LER BBA: Quad shunt inventory
• We have 8 of the IR2 shunts completed, three were installed
before the safety stand-down.
• Resistors available off-the-shelf (18 W, giving 9 W shunts with two in
parallel) will shunt 1.8-1.9 % magnet current.
• Resistors for the remaining 6 boards are on order, we
expect delivery this week.
• These will also be 9 W shunts.
• Boards are ready, just awaiting resistor delivery.
• Cable plant is in place. Final checkout SCP  Shunt required.
Dec. 14, 2004
PEP-II MAC
Tonee Smith, ILC
8
LER BBA: IR2 Quad Shunts
String
Magnet R
Mag I
Mag V
Shunt V
Shunt R
Shunt I
Shunt %
Shunt P
QFCY1.1
0.18
70
12.8
11.3
9
1.3
1.79
14.1
1.2
0.18
70
12.8
11.3
9
1.3
1.79
14.1
1.3
0.18
70
12.8
11.3
9
1.3
1.79
14.1
1.4
0.18
70
12.8
11.3
9
1.3
1.79
14.1
QDCY2.1
0.18
106
19.3
17.8
9
2.0
1.87
35.3
2.2
0.18
106
19.3
17.8
9
2.0
1.87
35.3
2.3
0.18
106
19.3
17.8
9
2.0
1.87
35.3
2.4
0.18
106
19.3
17.8
9
2.0
1.87
35.3
QFCX3.1
0.18
140
25.6
24.1
9
2.7
1.91
64.3
3.2
0.18
140
25.6
24.1
9
2.7
1.91
64.3
QDCX2.1
0.18
147
26.7
25.2
9
2.8
1.91
70.6
2.2
0.18
147
26.7
25.2
9
2.8
1.91
70.6
2.3
0.18
147
26.7
25.2
9
2.8
1.91
70.6
2.4
0.18
147
26.7
25.2
9
2.8
1.91
70.6
Dec. 14, 2004
PEP-II MAC
Tonee Smith, ILC
9
Quad shunt installation, QD/QF
• We have installed 1-2 moveable shunts per half-arc (2-4
shunts per IR/micro), based on quad(/sext) population.
– The shunts hook directly across the busses of a quad with leads
that bear an uncanny resemblance to automotive jumper cables.
– Shunt blocks/enclosures are grounded to the PEP magnet rafts.
• After a round of BBA, these shunts will be moved at the
next opportunity to a neighboring candidate QD or QF.
• Lather, rinse, repeat. (Two RODs to complete the QD/QF
magnets)
Dec. 14, 2004
PEP-II MAC
Tonee Smith, ILC
10
Quad shunt installation, IR2
• We are planning to complete installation of one
shunt on each of the 14 QF/DCX/Y quads in IR2.
– The shunts also hook directly across the busses of the
quads, but will not be moved from magnet to magnet.
– Modifications to the shunt covers have been made to
prevent contact with electrical hazards within.
• IR2 magnets are not PPS-interlocked, and the shunts are not
contained within existing magnet covers.
• We are prepared to install the eight we have pending
work approval, the remaining six as soon as they’re
ready.
Dec. 14, 2004
PEP-II MAC
Tonee Smith, ILC
11
Quad shunt controls
• To the control system, the shunts look like generic digital
devices with a corresponding analog readback.
–
–
–
–
Moveable shunts have names like: PR04 SHUNT1, 2, 3…
One digital control (IDOM bit) per shunt (command ON/OFF)
One status (ON/OFF) reflecting that IDOM bit
One ASTS value reflecting current through the shunt resistors
• Not presently calibrated well enough to tell more than whether the shunt is
shunting or not, really.
– We’ve requested that the shunt on/off status be on the SDS CUD
under LGPS with ON being RED.
Dec. 14, 2004
PEP-II MAC
Tonee Smith, ILC
12
SCP Panel & Analog display
Dec. 14, 2004
PEP-II MAC
Tonee Smith, ILC
13
How it all works
• We are creating a flat file to hold the information of which
shunt is on which quad, with a list at the bottom of which
shunts can go to which quads.
– This file will live on the VAX with an entry in e-log (which e-log
to be determined) with its location.
– The person who physically moves the shunts to new magnets is
required to change this file.
• For data acquisition, a button macro will prompt which
magnet or which shunt you wish to do BBA on, then load
up a CRR and take data.
• Data to be analyzed offline by the Woodley/Wolski coupled
analysis matlab code.
Dec. 14, 2004
PEP-II MAC
Tonee Smith, ILC
14