MICE Target Report Chris Booth (for target team) Sheffield 24 th March 2010.

MICE Target Report

Chris Booth (for target team)Sheffield

24th March 2010

Chris Booth University of Sheffield 2

History & Overview• T1 – DLC bearings – running in ISIS

– >155k + 50 k actuations

• T2 – nominally identical to T1– Bearing failed rapidly

• T2.2 – like T1, improved QA– Failed after ~80k actuations

• T2.3 – same stator & shaft as T2.2– New Vespel (polyimide) bearings– Tested for >2.1M pulses in R78

Results of T1 running, T2.3 tests, and plans

3University of Sheffield

BCD (beam centre distance) Histograms

(analysis by Paul Hodgson)

T2 distribution 3-4 times as broad

Can be interpreted as a result of the target “sticking”

Use the BCD histograms as a diagnostic to spot changes in target performance

T1

T2

Chris Booth

T1 Calibration PlotsRunning in ISIS allowed subject to •“target integrity tests” every 10k (formerly 5k) actuations•400 pulses taken under standard conditions•Check for changes in behaviour•Inspections for dust every 50k actuations

0.4 mm

Overlay of Calibration Plots


Conclusions for Target 1

• Target continues to perform reliably• No sign of significant change in BCD distributions• No sign of dust production on view port

• Keep running!

Status of Target 2• T2 Vespel installed in R78 Jan 25th 2010• DLC coated shaft (from T2.2) – Vespel bearings• Same stator body as previous T2• Pulsed target continuously for 2.15×106 pulses• Approx. one month of operation at ~1 Hz• Two short interruptions, chiller failed 1/2/2010,

UPS failed 8/2/2010(!)• Neither problem associated with target mechanical

performance• Target was deliberately stopped for inspection• Very little dust on view-port (~ daily photos)


Early Mid Late

720k s 1680k s

Changeover ~1 day

T2 BCD over month

Start up periodDAQ gain changes

1×106 pulses

University of Sheffield

Look at BCD histograms in 3 regions

Region 1 Early operation120k – 360k pulses

RMS 0.135Asymmetric tail

Region 2 Mid operation720k – 960k pulses

RMS 0.122Asymmetric tail

Region 3 late operation1860k – 2100k pulses

RMS 0.155More symmetric with double peak

structure but broader

Chris Booth 9

Comparison of BCD plots for T1 (DLC) and T2 Vespel

RMS of T2 Vespel is approximately twice that of T1(Note different scales)

T2 Region 3 T1


T2 Acceleration over month

Chiller failure

Test power off

UPS failure


T2 Acceleration regions

Steady decline 848 to 838 ms-2

Stable operation (838 ± 5) ms-2

Increasedvariability

Early Mid Late

720k s 1680k s


Questions and CommentsHow would the target have performed if we had carried on pulsing ?

Remember we arbitrarily stopped at 2.15 × 106 pulses.

Does the early period correspond to the target “bedding in” ?

The mid period lasted approx. 1 million pulses where the target seemed to wear gradually.

There was a reasonably rapid (1 day) change in performance after which the target parameters were (slightly) more variable.

None of the variation seen above would compromise the normal target operation.

The typical beam centre varies more than the target BCD.


Disassembly & Inspection of Target 2(Jason Tarrant)

• Target stopped after 2.16M actuations

• Optics block removed & upper bearing exposed

• Bellows removed & lower bearing exposed

• Significant amounts of vespel dust, adhered to surfaces


• Disassembly – View of upper Bearing MICE Target

First look

Little dust(polished flat)

Most dust(rough flat)

Polished flat

Rough flat

Amalgamateddust balls

DustOn shaft,

On bearing,On lock ring

Survey point


• Disassembly – View of lower Bearing MICE Target

Dust around bearing,lock ring removed

Internal face

External face

Chris Booth 16

MICE Target• Observation – Dust

– Amount• Most at upper bearing – esp. anti-rotate rough flat side• (Only one flat on shaft polished)• Amalgamated at bearings – scraped off

– Location• Coated internal components, has escaped externally• How does it move / defy gravity?

– Thrown off?– Electrostatic attraction?– Vibration movement?– When let up to air?

– Attachment• Fixed – by what?



Next Steps?• Reduce wear & dust

production– Polished flats, burnished

bearing faces

– Possibly harder plastic (Duratron or Celazole)

– Improved stator? (See below)

• Observe when dust produced

• Trap dust in catcher

• Further tests start in May

Chris Booth 18

Stator QA• Is stator 2 different from stator 1?

– Map field, with assistance of group at Diamond

– Support rig built by Geoff Barber

– Chiller, PSU, temperature interlocksready

– Measurements to start this week

– Stator 3 (unwelded) built in Sheffield

– Permanent magnets will be (re-)measured

– Modelling (Paul Smith, Owen Taylor?) to connect field asymmetries with off-axis forces


Target Electronics & DAQ Upgrade• Phase 1 hardware complete,

tested (Paul Smith)

• USB interface to PC– Menu-driven interface in use

(see screen shots)

– GUI under development (James Leaver)

• Control, monitoring, error notification

• Much simpler interface (for non-experts!)

• Plan to exercise thoroughly in R78 before installation in ISIS– Soak-test during next bearing evaluation


Menu-driven controls

12-Mar-10 P J Smith - University of Sheffield

Framework for terminal code

programmed by James Leaver

21

Prototype GUI for Target Control

12-Mar-10 P J Smith - University of Sheffield

GUI screenshot provided by James.

The exact layout may change a bit

over the next weeks

22


Summary• Target 1 installed and operating well in ISIS

• Target 2 with plastic bearings performed reliably for >2M actuations

– Stopped for inspection, not due to failure

• Test & measurement programme for reducing and trapping dust

• Stators will be mapped to improve QA

• FPGA-based control essentially ready

– will give easier operation and enhanced monitoring

MICE Target Report Chris Booth (for target team) Sheffield 24 th March 2010.

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Transcript of MICE Target Report Chris Booth (for target team) Sheffield 24 th March 2010.