R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005 PHIN R. Losito CERN – AB/ATB 05/09/2005

R. Losito CERN-AB-ATBCare Steering Committee, Paris, 05/09/2005

PHINR. Losito

CERN – AB/ATB05/09/2005


WP1: Management

Website created

Maintainance and upgrade


WP2: Charge Production

3 GHz RF Gun

High efficiency photocathode comparison• Intermediate report done• Final report: reported to end of 2006 (no news from

Twente..). • Photocathode preparation equipment construction

– Under way, delays due to problems in refurbishing certain components, production of photocathodes should restart in November at CERN.

• Photocathode 3 GHz high field R&D– Dark current measurements, thin fim adherence under high field

etc..– Will start after arrival of the RF Gun (December/January?)

» Milestone will probably slip by some months



Photocathodes for SC Cavity

Photocathode preparation equipment ready (31/03/05)


FZR SRF Photogun – Cathode Preparation

The photocathode preparation system wascompletely assembled and its functionwas tested. It contains two pairs of evaporators for Te and Cs, the holderand heater for the cathode withtemperature measurement, a motordriven shutter, a measurement aperturefor photo current, and two depositionrate monitors allowing co-evaporation,and is equipped with a 262 nm, 10 mWlaser system. The computer control system(electronics and software) is ready.At present, the system is disassembledand the parts are being cleaned. Afterthat, the system will be assembled againin the clean room.



Photocathodes for SC Cavity

Photocathode preparation equipment ready (31/03/05)• The new preparation equipment was installed and

tested. At present it is being cleaned for installation in the clean room.

Photocathodes tests• Will start when material ready.



Laser Driven Plasma source

No fresh news from LOA …..


WP3, T1: LASER

Laser for the CTF3 Photoinjector: All the milestones have shifted by ~6 months due to the

late arrival of funding and long procurement delays due to specificity of the material.

An important deliverable reached is the laser oscillator: Built by HighQLaser (Austria), it is the first of his kind with

• rep rate of 1.5 Ghz• rms pulse lenght < 10ps• Jitter < 1 ps• Amplitude stability < 0.2 %


WP3, T1: Oscillator and preamplifier

The oscillator and preamplifier are now working to specification at RALThe additional preamplifier has delivered the required powerThe improved timing jitter seems to be due to low environmental noise at RALAnomalous photodiode measurements at CERN have been resolved

The results of the acceptance tests: HighQ acceptance tests Notes RAL acceptance tests

Laser repetition rate

1.4993 GHz Adjustable using a translation stage on a cavity mirror

Average power 10.3 W 10.5 W

Pulse width 5.3 ps

Beam quality M2 = 1.1 Measured with Coherent Mode Master

Long term stability

0.56% rms Over 13.5 hours

Timing jitter 123 fs (electronic)

126 fs (optical)

Measured with electronic mixer and also with optical reference oscillator, using cross-correlation

71 fs (electronic)

99 fs (optical)


WP3,T1: Amplifier procurement

Amplifier 1 assembly and testing will begin in SeptemberAmplifier 2 assembly and testing will begin in November

Amplifier 1 Amplifier 2

Laser diodes

Laser diode drivers

Focusing lenses

Laser rod

Mechanical components

Water chiller

Beam transport optics

Optomechanics

Diagnostics

Breadboard

Specified

Ordered

Delivered


WP3, T1: Updated layout of the system

• Recent modifications include final layout of HighQ system, extra diagnostics and “inversion” of the overall scheme to improve stability of beam delivery to the accelerator vault

• A timing and control system, compatible with the CERN architecture, has been specified

Table at CERN

Table at RAL

Beam size provided for 1st amplifier

1st amplifier

2nd amplifierThermal lensing compensation

Poc

kels

cel

l(s)

for

gene

ratin

g 1.

5 us

tra

inF

eedb

ack

sta

bilis

atio

n

Cod

ing

Del

ay li

ne

Beam size provided for SHG

Dia

gn. Beam size provided

for FHG

Dia

gn.

Breadboard

Amplifier beam heights ~ 12 cm

Beam

size provided for 2

nd am

plifier

Laser beam to cathode

350 cm

150 cm

HighQ oscillator

HighQ amplifierFaraday isolator

FO

M system

Diagnostics

: alignment check camera

: calibrated PD for power monitoring


WP3, T1: Time & Amplitude StructuringTime & Amplitude Structuring

PULSE SLICING

• Needs two large-aperture Pockels cells (single-pulse and 1.54s train) to handle highaverage power after Amplifier 2

• Current design includes programmable corrector to reduce systematic pulseamplitude variations to <0.1% RMS

• System is commercially available

AMPLITUDE STABILISATION

• If the intrinsic amplitude noise is low then a low-retardance Pockels cell will be adequate, requiring low drive voltage compatible with fast electronic amplifiers

• Performance will be dominated by the sensor and the feedback control electronics• Sensor and cell are commercially available but FC electronics need specialist design

PULSE CODING

• Requirement for a 7 MHz, multi-kV, drive waveform with <300ps switching time andbetter than 1% amplitude control makes a system based on a Pockels cell unviable

• The alternative is a fibre-optic (FO) modulator system placed after the oscillator where the average power is low

• The >10dB losses of an FO system will require more gain from the preamplifier• The FO system is commercially available and the preamplifier’s manufacturer can

increase its gain, but this will involve some delay, best left to the end of the program


FPG-05-10S

Output voltage at 50 Ohm 2-5 kV

Pulse width at 90% of Umax 0.3-0.5 ns

Rise time <100 ps

Fall time <500 ps

Maximum repetition rate 10 kHz

Timing stability (jitter) < 20 ps

Maximum sync/output delay time 100-150 ns

Input trigger 5 V

Power supply, DC 300 V

Dimensions 100x50x40 mm

New Fast Ionization Devices (FID) and Drift Step Recovery Diodes (DSRD)

New devices developed by the Ioffe Physical-Technical Institute of Russia Academy of Science in St. Petersburg. They are based on a new physical phenomenon: the elctrone-hole plasma supergeneration in solid state. This permits to have high operating voltage up to 5kV and the turn-on time less than 1 ns. The DSRD are diodes characterized by fast voltage restoration that assures low commutation jitter, unlimited life time, repetition rate that can be as high as megahertz and opening times can be less than 1 ns with 100 A current.

Customization of standard product. E.g:

WP3, T1: Fast pockels cell drivers


WP3, T1: (LASER) Timescales and deliverables

CARE SC Apr 2005 Current (Sept 2005) Deliverable Notes

03/2004 03/2004 Report on laser oscillator design

06/2005 06/2006 Laser oscillator test results

Laser oscillator and preamplifier working to specification at RAL.

06/2005 10/2005 Report on laser amplifier design

Amplifier design complete & procurement under way.

Report delayed to speed up procurement.

12/2005 02/2006 Report on UV conversion crystal comparison

Moved to follow amplifier tests.

11/2005 01/2006 Amplifier test results Delays in procurement.

06/2006 06/2006 Laser system test results and delivery to CERN

Staff deployment is being revised to hold delivery date (coding system may cause delay).


WP3, T2: Shaping of the UV laser pulse

UV time profile measured using amultishot cross-correlator with 200 fs resolution.

It is possible obtain rise-time < 1 ps and ripples < 30%


WP3, T3 : Low rep rate synchronization tests at LNF

-20 0 20 40 60 80 100 120 140 16015.0

15.5

16.0

16.5

17.0

17.5

18.0

18.5

19.0

Ph

ase

[d

eg

]

Time [s]

14 15 16 17 18 190

100

200

300

400

500

Y A

xis

Titl

e

X Axis Titlephase [deg]

lase

r p

uls

es

2856 MHz cavity

High energy UV @ 10 Hz

On time scale of few minutes (enough to

adjust the RF) the phase jitter is

within σRMS 0.63 deg [0.61 ps].

Further characterizations are foreseen.


Superconducting Nb cavities:

The two cavities were deliveredby ACCEL in March 2005.One is made of high-qualityNb RRR 300 for use in the gun,one of Nb RRR 40 for tests(instead of a Cu model, whichadditionally allows to checke-beam welding, warm tuning,and chemical treatment etc.)

WP4, T1: FZR SRF Photogun


WP4, T1: FZR SRF Photogun – RF Measurement and

Tuning

1: Sensors-vertical position, 2: Sensors horizontal Pos., 3: DC-Motor (bead pull drive), 4: Stepper motor (vertical pos.), 5: Motor control box, 6: Sensor hardware,

PC-controlled bead pull measuring device(principle) built at FZR in 2005.

3D-CAD-Model of the tuning machineused for warm tuning (to push andpull each cell to the right frequencies).The special cavity shape required tobuild such a machine at FZR.


WP4, T1: FZR SRF Photogun – Warm Tuning

Photograph of the cavity tuning machine with integrated bead pull measuring device.

Field profiles from bead pull measurements.

Before chemical treatment, warm tuningof the cavities has been carried out in orderto obtain the right frequency and thedesigned field profile (equal amplitudes inthe three TESLA cells and 64% in thehalf-cell).


WP4, T1: FZR SRF Photogun – Cathode Cooling System

The cathode cooling system mounted on the test bench flange. The rf heat load is simulated by an electrical heater (10 – 50 W).

Cathode withheater

Cooling body

Liquid nitrogenreservoir

The test of the cathode cooling systemhas been succeeded. In the SRF gun,the normal conducting cathode is insidethe SC cavity. With the test was proofedwhether the cathode heat load (from rffield) will be transported into the liquidN2 cooler. It was found that the coolingsystem works well and only a smallamount of the heat (some mW) will betransferred to the SC cavity.


CAVITY:Two Nb cavities (NbRRR300 + RRR40) have been delivered.Rf-tests and warm tuning has been performed at FZR. Chemical treatment will now start at DESY.

CRYOMODULE:Most of the main components (vacuum vessel, 80 K cryo-shield,magnetic shield, support frame, rf coupler, tuner, cathode cooler, cathode transfer system) have been delivered. Cathode cooler test has succeeded.

The tuner test is under way. He transfer line is ordered. PHOTO CATHODES:

The new preparation equipment was installed and tested. At present,it is being cleaned for installation in the clean room.

LASER:The upgrade of the driver laser system is under way (MBI).

DIAGNOSTICS: a diagnostics beam line is designed. The realization has started (BESSY).

WP4, T1: FZR SRF Photogun – Project Status


WP4, T1: 3GHz RF GUN

WP4 RF GUNS STATUS 1st RF Gun construction

After many tries of the manufacturer to do a elliptical shape, a

compromise was done: irises are done in 12 facets and it meets the

specifications.

ordered in the end of April, 4 months of delay, delivery in

beginning of September

Measurements and mechanical adjustments are planned for one month,

delivery of the gun by the end of December if everything goes well

RF gun at LAL

Laser was ordered to Opton Laser in July, delivery in 4 months

NEPAL room

Shielding

• Other Radio-protection study is under way to reduce the

cost


WP4, T1: Spectrometer for e-beam

No News from LOA


Conclusions

Work generally on track for CTF3 photoinjector, Photoinjector at LAL, SC RF Gun and studies of pulse shaping in Frascati.

Due to holidays and to injury of Andrea, difficult to get information about Twente, INFN – Mi, Loa.

Should be addressed at the next collaboration meeting.

Documents

R. Losito CERN-AB-ATB Care Steering Committee, Paris, 05/09/2005 PHIN R. Losito CERN – AB/ATB 05/09/2005