Undulator Commissioning Plans Heinz-Dieter Nuhn, SLAC / LCLS October 30, 2007

Undulator Commissioning Plans

Heinz-Dieter Nuhn, SLAC / LCLS

October 30, 2007

Getting the Undulator System Ready for Operation.

October 30, 2007

Undulator Commissioning Plans

1

Heinz-Dieter Nuhn, SLAC / LCLS

Nuhn@slac.stanford.edu

Getting Undulator System Ready for Operation

Installation and Rough Alignment

ADS Commissioning and Conventional Girder

Alignment

Pre-Beam Checkouts

PPS Verification

Commissioning with Beam

Commissioning of Electron Beam Components

Commissioning of X-Ray Beam Diagnostics

Characterization of Spontaneous Radiation

Generation and Characterization of FEL Radiation

Transition to Operation

October 30, 2007


2



ADS Commissioning and Conventional Girder Alignment

ADS (WPM & HLS) Commissioning

ADS Control System Checkout

Quadrupole Alignment to Straight Line (100 microns)

Monitored with ADS

Loose-End (BFW side of girder) Pre-Alignment

Using Portable WPM/HLS

October 30, 2007


3



Pre-Beam Checkouts

HVAC System Checkout

Control System Checkout

Network Configuration of IOC's

Timing System

Communication with ADS Checkout

Verification of individual Device Operation

Magnet Power Supplies and Interlocks

BPM Cable Checkout

BPMs

Beam Finder Wire

Undulator Motion Control Checkout

CAM Mover Motion Checkout

Transverse Slide Motion Checkout

Compound Motion Checkout

Electro-Magnet Polarity Checkout

Quadrupole Main Coils Polarity Checkouts

Quadrupole Trim Coils Polarity Checkouts

BFW System Checkout

October 30, 2007


4



Getting Undulator System Ready for Operation

Installation and Rough Alignment

Conventional Girder Alignment

Pre-Beam Checkouts

PPS Verification

Commissioning with Beam

Electron Beam Commissioning

Commissioning of X-Ray Beam Diagnostics

Characterization of Spontaneous Radiation

Generation and Characterization of FEL Radiation

Transition to Operation

October 30, 2007


5



LCLS Commissioning Parameters (Inj/Lin Example)

Parameter

RF rate

Beam rate

Drive-laser rate

Bunch charge

Drive-laser pulse length

Gun gradient

L0-b gradient

October 30, 2007


Value

30 Hz

Comments

30 Hz in linac (possible short-term 120 Hz linac rate in L0-BC1 for feedback tests, etc) - 120 Hz in gun for short time to verify full rate

≤30 Hz

120 Hz

200-500 pC

10 ps fwhm

120 MV/m

30 Hz e- beam as baseline – possible 120-Hz tests in L0-BC1 for short term verification of feedback, etc

120-Hz all the times – pulse-picker provides e

rate as required above

200-500 pC, depending on QE and diagnostics - short spans at 10 pC – later in ’07 we explore 1-nC

10 ps FWHM startup with possibility of 6-ps at 0.2 nC later – early laser tests may provide path to more convenient pulse-length changes

120 MV/m, although 110 MV/m is adequate in ‘07

24 MV/m 24 MV/m in L0b (not critical in ‘07)

6



Generic Staffing Plan

Two 8-hour shifts per day of e-

Two physicists per shift

One controls person per shift

At least one operator per shift assigned to LCLS

One engineer on call and when required for early system tests

One technician per shift (all 3) and one laser-physicist on call per shift

October 30, 2007


7



Electron Beam Commissioning to Tune-Up Dump

Beam and Beam Stability Characterization

Emittance

Energy Spread

Charge

Energy

Transverse and Longitudinal Profiles

Energy Dependent Optics Tuning

(Electron Beam Matching)

Energy Dependent Electron Beam Steering

(Launch Condition into Undulator System)

RF-Cavity BPM Commissioning

(2 RF-Cavity BPMs before Tune-Up Dump)

October 30, 2007


8



First Beam Through Undulator Vacuum System

Conditions for First Beam:

All Undulator Magnets Rolled-Out (Quads could initially be turned off, too)

Single Shot Operation

Send single electron bunch towards undulator

Read and evaluate as much diagnostics as possible along undulator

(such as BPMs, beam loss monitors, toroids)

Identify and remove sources of beam loss

Iterate

Low Charge: 200 pC or less

Diagnostics designed for micron-type resolution over 200-1000 pC range

Resolution drops proportionally for out-of-range charges.

Out-of-range resolution still sufficient for initial commissioning steps, which only requires resolution in the 100 micron range.

Goal: Get beam through vacuum chamber with minimum losses.

Reminder:

Main Constraint is to Protect Undulator from Radiation Damage

October 30, 2007


9



First System Commissioning

(A) All Undulators in Roll-Out Position

BBA Commissioning with Undulator Segments Rolled-Out

BFW Scan with Undulator Segments Rolled-Out

ADS Check-Out with Beam

(B) Roll-In Undulators

Transport Beam through individual Undulator Segments

Start at slot #33 (last Undulator Segment in line)

Check and correct trajectory change.

Transport Beam through multiple Undulator Segments

Start at last

Check and correct trajectory change.

BBA Commissioning with Undulator Segments inserted.

October 30, 2007


10



Commissioning of X-Ray Diagnostics

Direct Imager

Calorimeter

Spectrometer

Minimum Requirement

Slit

Solid Attenuator

Gas Attenuator

Ion-Chamber

Beam-Based K Measurement Components

October 30, 2007


11



X Ray Diagnostics

Gas

Detector

5 mm diameter collimators Hard x-ray

Monochromator

Solid

Attenuator

(K Spectrometer) Direct Imager

NFOV

Soft X-Ray

Offset mirror system e -

Slit

Muon

Shield

Gas

Gas

Detector

Soft Xray

Imager

Attenuator

Total

Energy

Thermal

Detector

October 30, 2007


12

WFOV

Hard X-Ray

Offset mirror system

Start of

Experimental

Hutches



Characterization of Spontaneous Radiation

Initially at 1.5 Angstrom to reduce damage issue

Start at low charge

Repetition rate of 10 Hz or lower will be sufficient

Start to characterize radiation at last undulator

Measure: total spontaneous energy / pulse spontaneous radiation spectrum wavelength of first harmonic spatial distribution around first spontaneous harmonic first harmonic wavelength spread spontaneous beam direction temporal variation in spontaneous beam parameters

Characterize radiation from each individual Undulator

Measure relative K of Undulator pair.

October 30, 2007


13



K Measurement: 2-Segment Scheme

Measure synchrotron radiation spectrum produced by two undulator segments, and scan K of one segment

K ’s are matched when spectrum has the steepest slope on high energy side of 1st harmonic peak.

Match segments pair wise until all segments are measured.

segments under test

October 30, 2007


14 undulator segments (33 total)



Angle-Integrated Spontaneous Spectrum for 2 Undulators with

D

K / K =

-

0.2 to +0.2%

D j

= 0

D x =



3 mm

D

K/K =

+

0.2%

0.1% rms e

-

0.003% rms e energy jitter

energy meas. resolution

2% rms charge jitter

0.5% charge meas. res.

0.5

s rms angle jitter

10 5 photons/pulse/0.01%

100 photon noise

100 beam pulses with natural energy jitter only

October 30, 2007


15

D

K/K = 0%

D

K/K =

-

0.2%


Simulations P. Emma


First Lasing at 15 Angstrom

Start with reduced number of undulators

Redo BBA after change of undulator configuration

Adjust tapering for spontaneous radiation losses, wakefields etc.

Verify that electron beam meets requirements

Use Laser Heater modulation method for increased sensitivity

Find SASE signal using Direct Imager or Calorimeter

Optimize Gain…

October 30, 2007


16



FEL Measurements

Desirable measurements as function of position along undulator :

Intensity (L

G

, Saturation)

Spectral distribution

Bunching

Desirable measurements after undulator :

1 % of X-Ray Pulse

Pulse length

Spatial shape and centroid

Divergence

Electron Bunch

Micro-Bunching

Exponential

Gain Regime

Undulator Regime

Saturation

October 30, 2007


17



Trajectory Distortion Method z-dependent x-ray measurement using e-beam kick

October 30, 2007


18

Quadrupole Displacement at Selectable Point along

Undulator

GENESIS Simulations by Z. Huang



Undulator Roll-Out Method z-dependent x-ray measurement using rollout

Undulator Segments can be removed by remote control from the end of the undulator. They will not effect radiation produced by earlier segments.

October 30, 2007


19



LCLS FEL Commissioning (2008 - 2009)

Oct 22, 2008:

Nov 3, 2008:

Nov 25, 2008:

LTU/Undulator/Dump Ready for Beam

Re-commission Inj./BC1/BC2/Linac to SL2 (<1 mo)

Commission LTU up to “TDUND” (<2 mo)

Jan 19, 2009:

May 14, 2009:

May 15, 2009:

May 15, 2009:

Jun 18, 2009:

Jun 19, 2009:

Jul 17, 2009:

Jul 31, 2009:

Aug 1, 2009:

Sep 1, 2009:

Oct 1, 2009:

Commission Undulator & Dump (3 mo)

FEE Ready for Beam (move earlier?)

First Spontaneous Light

FEL/FEE Commissioning (~1 mo)

Measure photon flux density in FEE

LATE

Commission FEE Soft X-ray Mirrors @ 15 Å (1 mo)

X-rays in NEH

First FEL Light

FEL Optimization (1 mo)

X-rays to Users in NEH @ 15 Å (1 mo)

Shutdown for PPS Certification (1 mo)

(beam rate  30 Hz)

Sep. 14, 2007

October 30, 2007


20



Summary

Plans for undulator commissioning are shaping up.

Detailed system checkout planned.

Diagnostics tools are at, or passed, the concept phase.

Beam based K -measurement method included.

Methods for gain curve measurements have been worked out.

Planned availability of x-ray diagnostics is late

Early x-ray profile and intensity diagnostics after main dump, desirable.

October 30, 2007


21



End of Presentation

October 30, 2007


22



Undulator Commissioning Plans Heinz-Dieter Nuhn, SLAC / LCLS October 30, 2007

Undulator Commissioning Plans

Plans for undulator commissioning are shaping up.

Planned availability of x-ray diagnostics is late

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Undulator Commissioning Plans Heinz-Dieter Nuhn, SLAC / LCLS October 30, 2007

Undulator Commissioning Plans

Plans for undulator commissioning are shaping up.

Planned availability of x-ray diagnostics is late

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