Wir schaffen Wissen – heute für morgen

Do you believe in Operation Statistics?Presented at the Accelerator Reliability Workshop 2011

Andreas LüdekePaul Scherrer Institut

Paul Scherrer Institute (PSI), Switzerland

PSI: Swiss national research center1300 employees

Proton facility: 1 MW cw beam– Spallation neutron source

PSI West: Large Research Facilities

Proscan SC cyclotron– Cancer therapy Swiss Light Source (SLS)

– e- storage ring– 400mA, 2.4 GeV

Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 2

Swiss Light Source Operation

• Swiss Light Source is• In operation since 2001• A user facility with 19 beam-lines in operation• Providing ~ 5000 hours beam to users per year

• Users need to apply for beam time• Just 30% of the proposals are accepted• Accepted users need to wait about 6 month for beam time

• One important metric to judge machine quality

€

Availability =Delivered _Beam _Time

Scheduled _User _Time

Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 3

3rd Generation Synchrotron Light Sources: AvailabilityAv

aila

bility

[%]

YearAndreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 4

Availability: "Concours des Alpes"Av

aila

bility

[%]

YearAndreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 5

Availability: "Concours des Alpes"Av

aila

bility

[%]

YearAndreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 6

Metrics of the Swiss Light Source (SLS)

• Availability definition:

• “Delivered_Beam_Time” = “Beam_for_Users” during “User_Time”• “User_Time" = “Scheduled_User_Time" + "User_Reserve_Time”

• Example for 2005:€

Availability =Delivered _Beam _Time

Scheduled _User _Time

€

Availability =4777h +175h (reserve )−82h (outages)

4777h=101.6%

€

Availability uncompensated =4777h +175h(reserve ) −82h(outages)

4777h +175h(reserve )= 98.4%

• Uncompensated Availability

Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 7

Elettra Metrics for Availability

• Thunderstorms are excluded from failure statistics at Elettra

• Example from 2005:

€

Availability =User _Time −Outages+Outages(Thunderstorms)

User _Time= 93.2%

€

Availability (Storms) =User _Time −Outages

User _Time= 92.3%

• Availability including outages from thunderstorms:

Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 8

Availability: "Concours des Alpes” correctedBa

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[%]

YearAndreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 9

Special Events: ESRF 2005 and the Crotch Absorber

● In March 2005―A water-to-vacuum leak―Five days of user operation lost 120 hours downtime

● ESRF statistics 2005―Availability 97.6%, ―Total User Operation 5496 hours 131 hours downtime

• How can that be? ―All users of 5 days re-scheduled―Not counted as downtime

Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 10

What can we learn from this?

● Availability statistics not proportional to system reliability

● But large effort spend to compile downtime statistics

● Accurate failure data exists, but kept internal. Why?

● If that would be public, what could it be used for?

Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 11

RF arcing at the Swiss Light Source

• Background• SLS has 60 to 100 beam outages per year• About 20 outages were caused by RF arcs

• Inquiry• Asking around at the EPAC’08: “What is your experience with arc detectors?”• Answer: arc detectors are often unreliable!

• Action• We are replacing detectors with arc-coincidence detectors

• Result• No arc interlock from any upgraded detector!• Single diodes still show arcs, but do not cause interlocks

Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 12

• Conclusion• We had in 10 years 200 unnecessary beam losses!

What can we do?

Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr-2011 Slide 13

• What we do now– We do your own mistakes– Sometimes we share selected insights during workshops

• What we should do– Learn from the failures of others– Create a database of all outages of many facilities!

• How to do that?– Define a simple document format– Provide a web-platform to publish downtime event data

• I’ll start, will you join?

• Participate in the Friday morning discussion!

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