WG2 Summary:Diagnostics, measurements, and

commissioning

Aaron TremaineSteve Lidia

And a host of others who shall remain blameless.

WG2 discussions

Talks given

High brightness measurements, e.g. LCLS (~kW)

High current measurements leading to MWAssume bunch train

Commissioning

all for Q = 1 nC

0.8

1.2

1.6

2.0

2.4

2.8

3.2

0 3 6 9 12 15 18 21 24 27 30

Ibuck, A

no

rm.

em

itta

nc

e /

mm

m

rad Ex

EySQRT(Ex*Ey)

Φ = Φm – 5°

Imain = 326 A

20. 8. 2004

0.8

1.2

1.6

2.0

2.4

2.8

3.2

320 322 324 326 328 330

Imain, A

no

rm. em

itta

nce / m

m m

rad Ex

EySQRT(Ex*Ey)

Φ = Φm

Ibuck = Imain * 0.075

24. 8. 2004

VUV-FEL (30 nm)

VUV-FEL (6 nm)

XFEL

• min. emittance improved

• geom. average improved

• still a long way to go for XFEL requirements !

Transverse Emittance measurements

Courtesy A. Oppelt

Determine Longitudinalφ-Space at Linac Entrance

Measure Energy Spectra vs linac phaseLinear analysis allows only linear time energy correlationsFit τ11, τ12, τ22, Vlinac, and θlinac

Quad scan and fit Twiss parameters

Technique analagous to quadrupole scan of transverse emittance

Longitudinal Emittance Measurement

3 m linac(vary φlinac)

GunSpectrometer

Energy Screen

QuadDoublet

Courtesy, J. Schmerge

1. ImplementationTV & Streak-camera

Magnetic Kicker

~100 us~1-2 us

10 W0.1 W

t

E-beam

Phosphor + OTR

Ti Foil

Vacuum chamber

Courtesy Timur Shaftan

UCLA/ATF chicane compressionexperiments

• Extend UCLA chicane experimentsto regime with significantacceleration-field

• Chicane designed, fabricated andcharacterized at UCLA

• Extensive simulation work• Coherent radiative effects central to

mission• Add to ATF core capabilities…

– SASE FEL– Wakefield studies

Coherent radiationexit port

Bunch length diagnostic comparison

NoNoRelativeNoYesEnergyWake-loss

NoYesAbsoluteYesNoElectro OpticSampling

NoNoAbsolute(2nd moment

only)

NoNo for CSRYes for CTR

CoherentRadiationAutocorrelation

YesNoRelativeYesNo for CSRYes for CTR

CoherentRadiationSpectral power

NoNoAbsoluteNo: 3 pulsesYes: Steal 3pulses

RF TransverseDeflectingCavity

Detectµ bunching

Timingmeasurement

Abs. or rel.measurement

Single shotmeasurement

Invasivemeasurement

Device Type

Courtesy Patrick Krejcik

High Brightness, <5kW

Word document

Average Power ->1 MW

Measurements of single bunches interesting, but not necessary(assuming high brightness bunches)

Invasive is not robust solution, water cooled OTR good to several kW

Kick out several pulses and make measurements

Consult Damping Ringers for kicker specs

Commissioning

Common problem -Not enough diagnostics near source/low energyReal estateBeam dynamics

Low rep rate & charge start, ramp up to high rep rate & chargeWatch for changing source physics

When low ε important, source very important

Usually diagnose source on test stand and installMeasurements downstream, hard to diagnose source again

Halo & beam loss

For MW beam, 10 kW halo conceivableWith wire scanner progressively measure haloTry to remove at low energy (lower power)Scrappers

Where does halo form? Simulations?

Beam lossRadiation detector schemes, LC community

Look to LC for collimation schemes, takes a lot of beamline

Other issues

2 screen OTR emittance, useful > 15 MeV

Are there situations where you need to know more than our list?User definedMulti-channel striplines, higher order content

Radiation environment in high current scenarioX-ray damage to equipmentAre diagnostics/electronics reliable