m. ferianis feb 2006 @ ucla overview of fermi diagnostics

M. Ferianis feb 2006 @ UCLA

Overview of FERMI Diagnostics


FERMI @ ELETTRA


FERMI footprint


FERMI main parameters


FERMI layout (...work in progress)

Laser heater

X-band linearizerspreaderEnergy/ H, V collimatorsdump


accurate photo-injector characterisation:

emittance, charge profile, energy spread seeded FEL scheme: whole bunch / fresh bunch (bunch core)

calls for slice measurements:

longitudinal charge profile, emittance, energy spread transverse and longitudinal overlap between e- beam and laser

high resolution BPM and bunch arrival monitors

shot-to-shot feedbacks stability of output FEL radiation mm to sub-mm bunch length; currently two options:

medium bunch: LB= 0.21mm (700fs) short FEL pulse

long bunch: LB= 0.57mm (1.9ps) long FEL pulse

Guidelines of diagnostics for FERMI


Some relevant beam parametersfor diagnostics

*calculated assuming a normalized emittance of 1.2 mm mrad

Medium Bunch

Energy

[MeV]

Charge

[nC]

Bunch Length

[ps / mm, FWHM]

Transverse Size*

3xx,v[mm]

Entrance BC1 220 0.8 5.4 / 1.620 500

Exit BC1 220 0.8 2.6 / 0.780 300

Entrance BC2 600 0.8 2.6 / 0.780 300

Exit BC2 600 0.8 0.7 / 0.210 180

Long Bunch

Entrance BC1 220 1 11 / 3.3 500

Exit BC1 220 1 5.6 / 1.68 300

Entrance BC2 600 1 5.6 / 1.68 300

Exit BC2 600 1 1.9 / 0.57 180


Injector diagnostic beamline BC1 diags 1st RF deflector @ 220MeV (down-stream BC1) BC2 diags 2nd RF deflector @ 1.2 GeV pre-FEL diagnostic station (downstream the spreader) post-modulator diagnostic station intra-radiator diagnostics (multipurpose pop-ins) post radiator diagnostic station (FEL diags)

Guidelines of diagnostics for FERMI


Currently addressed issues on Diagnostics

review of FERMI parameters for diags. the team @ ELETTRA: dynamically growing... overview of main FERMI diagnostics and associated

measurements integration of diagnostics into the machine, i.e. defining:

dedicated machine optics vacuum chamber x-sections alignment strategy RF power needs for diags optical clock (laser pulse)

Conceptual Design Report write-up


Gun S0A/BLaserHeater XLINAC1

BC1 BC2

LINAC2 LINAC3 LINAC4 SPRDFEL1

FEL2

Gun / injector Diagnostics

Gun:

•Energy/energy spread •Charge•Spot size•Position •Bunch length•Thermal emittance



BC1 BC2


FEL2

Laser heater based diagnostics

775 nm seed laser derived from 1550 nm timing signal 120 kW, 10 ps

Cross-polarized 5-period undulators

Matching quads into heater

Matching quads into linac

YAG screen, BPM

YAG screen, BPM

Laser Heater :

Electron beam timing relative to optical pulse

Electron beam current profile

Slice emittance

W.Graves, MITS.Spampinati, ELETTRA


Energy, Energy jitter, Vertical slice emittance: BMP –collimator -screen

Bunch length monitor: CSR output power detection to feedback loop

Micro-bunching: CSR output for detection by THz spectrometer.

Bunch arrival time measurements: fs Streak camera (ref pulse)

wide band ring electrode with EO acquisition

Bunch length, compressor tuning:

• BC1: 1st RF Deflector, streak camera for OSR

• BC2: 2nd RF deflector, EO sampling


BC1 BC2


FEL2

BC1 & BC2 Diagnostics


Diagnostics station at the end of linac :

Vertical and Horizonthal RF deflecting cavity:

Slice emittanceCSR effect on horizonthal emittanceSlice Energy Spread

EOS bunch arrival time monitor:

Bunch arrival time

Arrival time jitter

Bunch length

Features: single shot (SLAC spatial convertion scheme, 100fsec resolution, MLO or SEED laser

pulses as a probe)

Overview of FERMI @ Elattra Diagnostics


BC1 BC2


FEL2DIAGS


FEL 1&2 :

Entrance of modulators:

X,Y position and divergence: high precision cavity BPM

Intra - radiators:

e-beam and FEL radiation position and spot size: pop-in station with YAG screens

e-beam X,Y position: cavity or button BPM

microbunching and power growth: OTR/CTR

monitorinig during operation CDR

Exit of last radiator FEL radiation: (under development by user group):

Single shot Spectral distribution monitor

FEL radiation arrival time by respect to user laser determined by cross correlation

techniques (De Silvestri) and advanced streak cameras.

Overview of FERMI @ Elattra Diagnostics


BC1 BC2


FEL2DIAGS


EB= 240 MeV; n=1.5 mm mrad;a=20 mm vg/c=0.0312 (L=1m=100ns)a=12.5 mm; vg/c=0.0123(L=1m=270ns)fRF=2.998 GHz;D=45 m; S=45 m; =90 deg;

Traveling wave deflectorperformances for low energy case

Long bunch: 1.5 mm

Short bunch: 0.4 mm

Ldef=2m


EB= 1.2 GeV; n=1.5 mm mrad;a=20 mm, =1 F=0.85sa=12.5 mm, =1 F=1.0sfRF=2.998 GHz;D=45 m; S=45 m; =90 deg;

Standing wave deflector: performances for high energy

case


Cavity BPMin collaboration withM Poggi, INFN PD

Beam pipe radius: to be defined according to Vacuum & Zbeam current value R=6mm; ID gap (vacuum side) calls for R=3.5mm

Extraction waveguide radial position: to be checked with simulationOptimum position for the RF connecotr on the waveguideSignal amplitude dependance on Qbunch (analytical eval.) Achievable mechanical accuracy on prototype: 10mSetting up the RF test bench (Network An.@20GHz):

BPM rigidly fixed to supportcoaxial moving wire, over ±1mm, acuracy and reproducibility <2m

prototype issues: no UHV, flanged + RF sliding contacts, equipped with SMA connectors (DC to 18 GHz)


Principle:• Isolated impedance-matched Ring Electrode

installed in a „thick Flange“• Broadband, Position independent Signal• One installed after the Gun, each magnetic Chicane

(both BCs, the Collimator + before Undulator)• BC´s: Energy Fluctuations -> Phase Fluctuations

TOF Measurement: Resolution ≈ 0.2° or 0.4 ps• Fast timing signals with sub ps resolution• Very simple design of pickup• Two output signal provided (left & right)

~550 mV/psPhase Monitor

Phase monitor (collaboration with Desy)

Courtesy: H. Schlarb, F.Löhl


EO acquisition of the wide band ring electorde signal

~ 1.3 GHz

DAC

DOOCS

MasterLaser

Oscillator

piezo-fiber-

stretcher

piezo-controller

~~~

1.3 GHz 10 GHz

200 MHz~~~

81 MHz limiter

ADC100 MHz

12 / 14 Bit

clock trigger

DOOCS

phasemonitor

EOM200 MHz

bias-voltage

10 kHz

VM

Courtesy: H. Schlarb, F.Löhl

~550 mV/ps

12 dB

MLORF master

BPhM

Mach-Zehnderinterferometer

Later: limiter


Impact from vacuum chamber sections

Type Dimensions

Linac circular D=30 mm

Compressors rectangular W=60mm,

H=30mm

Undulator elliptical H=7mm

W= tbd (vacuum)


Timing and Synchronization

m. ferianis feb 2006 @ ucla overview of fermi diagnostics

Documents