Summary from TTF2 Working Group

Jean-Paul Carneiro, Markus KoerferDESY, Hamburg

TESLA COLLABORATION MEETING

ORSAY, 7-Sept-2004

TESLA COLLABORATION MEETINGWORKING GROUP : TTF2LAL ORSAY, 7-SEPT-04

Morning (9H00 10H30, 11H0012H30)

9H00 10H30 Carneiro

• Cryogenics Installations TTF2 in 2004 and Future Plans Lange (20’)• TESLA Cavities in the VUV-FEL LINAC Modules Kostin (20’)• Status of the TTF-II vacuum system Zapfe (20’)• Power Supplies for TTF2 and Pulse Cable for Modulator Eckoldt (30’)

11H00 12H30 Koerfer

• Status RF System Choroba (15’) • Commissioning of the LLRF for the VUV-FEL Simrock (10’)• RF Control Improvement for TTF II with low latency FPGA feedback Jezynski 10’• VUV-FEL Controls Rehlich (15’) • TTF 2 Diagnostics Status and Availability of Toroids, BPMs, … Castro (15’)

Afternoon (14H00 16H00, 16H3018H00)

14H00 16H00 Carneiro

• TTF-VUV FEL Optical Systems Castellano (15’)• Photoinjector Laser Operation and Cathode Performance Sertore (20’) • Beam based alignment, Dark current and Thermal emittance Miltchev (20’)• Status of Emittance Measurements at the TTF/VUV-FEL Injector Honkavaara (20’)• First Measurements on HOM-Based Alignment in the TESLA Cavities Baboi (20’)

16H30 18H00 Koerfer

• Improvements in LLRF control algorithms and automatio Brandt (20’) • TTF2-Time-Of-Flight Measurements Kollewe (20’)• TTF2 Start-Up Simulations Yurkov (20’)• TTF2 commissioning strategy Castro (10’) • Discussion about commissioning

Prepared but not presented (available on the web)• Attempt of measurement of linear dispersion… Golubeva (10’)• Commissioning 445-MeV Optics of the TESLA Test Facility Linac Balandin (10’)• Velocity bunching simulations for TTF2 Carneiro (10’)

Cryogenics Installations TTF2 in 2004 and Future Plans

-Assembly and installation of Module M2* (old type II) for Position ACC1-Commissioning of the new TTF2 set up with 5 Cold Accelerating Modules-Cool down, operation and tests of the new TTF2 set up-Shut down June-04 until September-04-Cryogenic operation possibillities/redundancies

Future:-Preparation and assembly Module M6 (new type 3)-Fermilab buildts 3rd Harmonic Module (3.9GHz)-Cryogenic supply for Superconducting Magnetic Energy Storage SMES-Module Teststand-Update Cold Box Hall 3 (2 new screw compressors already in operation)

R. Lange

TTF2 since March 2004

ACC5 M5 ACC4 M4 ACC1 M2*ACC2 M1*ACC3 M3*

VBVB

BCBTL2 BCBTL1

FermilabFeedbox

ACC2 Transferl ACC1 Transferl

GUN

BC2BC3

Endcap

Overview:21-Mar-04 Start cool down28-Mar-04 4.3K/1.1bar29-Mar-04 2 K / 31mbar07-Jun-04 Shut down, but modules stay cold at 4.3K/1.1bar01-Sep-04 End of shut down

Linac TransferFrom/to CB HERA or CB Hall 3

Cryo losses static [Watt]:

Total Module40/80K 1300 74 4.3K 320+1.6g/s 132.0K 21 <3.5

Automated Cryo-operation for TTF2-Linac

R. Lange

TESLA Cavities in the VUV-FEL LINAC Modules

D. Kostin

Modules Operating Gradients

1 1* 2 2* 3 3* 4 50

5

10

15

20

25

TESLA500

EA

CC [M

V/m

]

module

ACC2

ACC1

ACC3 ACC4 ACC5

D. Kostin

Cavities @ ACC1

1 - Z54 2 - Z51 3 - D42 4 - D37 5 - AC72 6 - C47 7 - Z53 8 - AC690

5

10

15

20

25

30

35

FE

Mod

ule

23.04.2004

Module 2*

EA

CC [M

V/m

]

Cavity

Cryostat tests: Vertical Horizontal Module

EP cavity

D. Kostin

EP Cavities

0 5 10 15 20 25 30 35 40109

1010

EP cavities: Vertical, Horizontal and Module tests

Q0

Eacc

[MV/m]

AC70 V AC70 H AC72 V AC72 H AC72 M AC73 V AC73 H

D. Kostin

(AC72 is installed in ACC1)

S. Choroba

S. Choroba

S. Choroba

S. Choroba

S. Choroba

S. Simrock

S. Simrock

K. Zapfe

K. Zapfe

K. Zapfe

K. Zapfe

K. Rehlich

K. Rehlich

K. Rehlich

TTF 2 Diagnostics Status andAvailability of Toroids, BPMs, …

Prepared by D. Nölle

P. Castro

STATUS Installation of diagnostics is completed; exception: BPM electronics

• BPM electronics available by end of 2004 (first boards maybe in November).

• For the commissioning: use 20-15 TTF1 electronics (DESY & Frascati units)– Not useful for undulator (<- Electronics container inside the tunnel)

• Problem: Orbit tuning is not possible to required precision– in the collimator– in the undulator

P. Castro

TTF/VUV-FEL Photon DiagnosticsStatus and Availability

Prepared by R. Treusch

P. Castro

Availability of VUV FEL diagnostics

Parameter Detector(s) Online availableIntensity &

Profile

thermopiles,

PtSi photodiodes,

MCPs

no

no

limited

now

Intensity &

Position

Gas Ionisation Detector YES April 2005

Spectrum Grazing incidence

spectrometer (tunnel)

no now(Commissioning)

Spectrum VLS Grating Spectrom. YES mid/end 2006

Timing Streak camera YES April 2005

Timing Auto-/Cross-Correlators YES ? (experimental

stage)

P. Castro

TTF-VUV FEL TTF-VUV FEL OpticalOptical SystemsSystems

LNF Frascati:

L. Cacciotti

M. Castellano

G. Di Pirro

O. Giacinti

R. Sorchetti

Roma 2 :

L.Catani

E. Chiadroni

A.Cianchi

M. Raparelli

DESY

K. Honkavaara

M. Castellano

Total Camera Number

18 Standard Optical System

3 Gun Camera

4 Fixed magnification (1 BC2 3 Bypass)

2 Diffractors

All of them are working

M. Castellano

M. Castellano

K. Honkavaara

K. Honkavaara

K. Honkavaara

K. Honkavaara

D. Sertore

D. Sertore

D. Sertore

04/18/23 J-H.Han,M.Krasilnikov,V.Miltchev 38

1. Beam based alignment

Laser alignment

Solenoid alignment

2. Dark current

3. Thermal emittance

Beam based alignment, Dark current and Thermal emittance measurements

J-H.Han,M.Krasilnikov,V.Miltchev, PITZ, DESY, Zeuthen

V. Miltchev

Beam Based Alignment: Conclusions

• Beam based alignment (BBA) of the gun can be done in two consequent steps:

1. Alignment of the laser on the cathode

2. Solenoid alignment

• Beam based laser alignment at PITZ is a well-established procedure. To implement it at TTF a calibrated camera at double diagnostic cross screen is required

• Mechanical beam line misalignment complicates the BBA, introducing an additional uncertainty

• Some steps in the gun solenoid alignment have been done. It is complicated by an uncertainty introduced by mechanical beamline misalignment, not perfectly aligned laser on the cathode and some uncertainty in machine parameters (rf field amplitude and absolute phase, solenoid calibration). For further alignment more detailed study is needed.

V. Miltchev

Modeling of the Field Emission SourceWell conditioned(less dark current) Edge of the Mo plug

8000 macro particles

Cs2Te flim (5 mm )2000 macro particles

Mo plug (16 mm )8000 macro particles

Edge of Cs2Te film2000 macro particles

V. Miltchev

FC1 and FC2 (~42 MV/m)

0

40

80

120

160

200

0 100 200 300 400main solenoid current (A)

dar

k c

urr

ent

( m

A)

simulation

measurement

0

40

80

120

160

200

0 100 200 300 400main solenoid current (A)

dar

k c

urr

ent

( mA

)

simulation

measurement

Main reason of the mismatch between measurement and simulation:beamline misalignment and the effect of steerers. lower energy part of the dark current is filtered out.

Faraday cup 1 Faraday cup 2

V. Miltchev

The final goal is to estimate the average kinetic energy Ek of the emitted photo electrons.

Assuming isotropic emission:

An estimate for could be given by measuring the transverse

emittance vs. laser spot r.m.s. size provided that RF, SC ≈ 0

Use very small charge (2-3 pC) and short laser pulses (6-8 ps FWHM)

Use single slit scanning and/or solenoid scan to measure emittance

Check the dependence of the transverse emittance on applied electric field on the cathode

2

00

5.13

2

d

dEE

E

Eε th

kk

th

d

d th

Thermal emittance measurements

V. Miltchev

Thermal emittance measurements

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 0.2 0.4 0.6 0.8 1 1.2

r.m.s. size / mm

emit

tan

ce/

mm

mra

d

Emitt_X

Emitt_Y

Transverse emittance for different r.m.s. laser spot sizes measured with the single slit scanning method at a charge of about 3pC and an accelerating gradient at the cathode of 32 MV/m.

eV 0.9-0.8 E mrad .. k

d

d

V. Miltchev

Thermal emittance measurements

The transverse emittance was measured for very low charge of 2-3 pC and short laser pulses of 6-8 ps FWHM

The scaling of transverse emittance with laser spot r.m.s. size was measured

The average kinetic energy Ek of the emitted photo electrons was estimated to be 0.8 ± 0.1eV

Thermal emittance was measured as a function of the applied field a the cathode

An increasing of the thermal emittance with accelerating gradient was observed

Summary

V. Miltchev

N. Baboi

N. Baboi

N. Baboi

M. Kollewe

M. Kollewe

M. Kollewe

M. Kollewe

M. Kollewe

M. Yurkov

M. Yurkov

M. Yurkov

M. Yurkov

TTF2 commissioning strategy

P. Castro

P. Castro

BEAM COMMISSIONING STEPS - SUMMARY

1st beam (bypass)

• re-commissioning of gun + injector

• setup cavity phases ACC2-5 beam energy

• setup bunch compression

• setup beam linear optics, optimize orbit

• commissioning of diagnostics

3 weeks

FEL 30 nm 1 bunch

• setup collimation

• emittance measurements and optics matching

• beam-based alignment in undulator section

• commiss. of photon diag. with spon. emission

10 weeks

Saturation+ 6-100 nm

• commissioning of FEL diagnostics

• study of FEL beam, compression schemes, etc.

• establish reproducible settings, etc.

8 weeks

P. Castro