PHIN

1
PHIN

• R. Losito
• CERN AB/ATB
• 05/09/2005

2
WP1 Management

• Website created
• Maintainance and upgrade

3
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 RD
• 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

4
WP2 Charge Production

• Photocathodes for SC Cavity
• Photocathode preparation equipment ready
  (31/03/05)

5
FZR SRF Photogun Cathode Preparation
The photocathode preparation system
was completely assembled and its function was
tested. It contains two pairs of evaporators for
Te and Cs, the holder and heater for the
cathode with temperature measurement, a
motor driven shutter, a measurement aperture for
photo current, and two deposition rate monitors
allowing co-evaporation, and is equipped with a
262 nm, 10 mW laser system. The computer control
system (electronics and software) is ready. At
present, the system is disassembled and the parts
are being cleaned. After that, the system will be
assembled again in the clean room.
6
WP2 Charge Production

• 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.

7
WP2 Charge Production

• Laser Driven Plasma source
• No fresh news from LOA ..

8
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 lt 10ps
• Jitter lt 1 ps
• Amplitude stability lt 0.2

9
WP3, T1 Oscillator and preamplifier
The results of the acceptance tests
The oscillator and preamplifier are now working
to specification at RAL The additional
preamplifier has delivered the required power The
improved timing jitter seems to be due to low
environmental noise at RAL Anomalous photodiode
measurements at CERN have been resolved
10
WP3,T1 Amplifier procurement
Amplifier 1 assembly and testing will begin in
September Amplifier 2 assembly and testing will
begin in November
11
WP3, T1 Updated layout of the system
350 cm
HighQ oscillator
Coding
1st amplifier
FOM system
Feedback stabilisation
HighQ amplifier
Faraday isolator
Diagnostics
Beam size provided for 1st amplifier
Delay line
Beam size provided for 2nd amplifier
Pockels cell(s) for generating 1.5 us train
Laser beam to cathode
Beam size provided for SHG
Beam size provided for FHG
150 cm
Diagn.
Diagn.
Thermal lensing compensation
2nd amplifier
Table at RAL
Breadboard
Amplifier beam heights 12 cm
alignment check camera
Table at CERN
calibrated PD for power monitoring

• 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

12
WP3, T1 Time Amplitude Structuring

• PULSE SLICING
• Needs two large-aperture Pockels cells
  (single-pulse and 1.54ms train) to handle
  high average power after Amplifier 2
• Current design includes programmable corrector
  to reduce systematic pulse amplitude variations
  to lt0.1 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 lt300ps switching time and better
  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 gt10dB losses of an FO system will require
  more gain from the preamplifier
• The FO system is commercially available and the
  preamplifiers manufacturer can increase its
  gain, but this will involve some delay, best left
  to the end of the program

13
WP3, T1 Fast pockels cell drivers
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.
New Fast Ionization Devices (FID) and Drift Step
Recovery Diodes (DSRD)
Customization of standard product. E.g

FPG-05-10S                                                
Output voltage at 50 Ohm 2-5 kV                                              
Pulse width at 90 of Umax 0.3-0.5 ns                                              
Rise time lt100 ps                                              
Fall time lt500 ps                                              
Maximum repetition rate 10 kHz                                              
Timing stability (jitter) lt 20 ps                                              
Maximum sync/output delay time 100-150 ns                                              
Input trigger 5 V                                              
Power supply, DC 300 V                                              
Dimensions 100x50x40 mm                                              
14
WP3, T1 (LASER) Timescales and deliverables
15
WP3, T2 Shaping of the UV laser pulse
UV time profile measured using a multishot
cross-correlator with 200 fs resolution. It is
possible obtain rise-time lt 1 ps and ripples lt
30
16
WP3, T3 Low rep rate synchronization tests at
LNF
On time scale of few minutes (enough to adjust
the RF) the phase jitter is within sRMS 0.63
deg 0.61 ps. Further characterizations are
foreseen.
17
WP4, T1 FZR SRF Photogun
Superconducting Nb cavities The two cavities
were delivered by ACCEL in March 2005. One is
made of high-quality Nb RRR 300 for use in the
gun, one of Nb RRR 40 for tests (instead of a Cu
model, which additionally allows to check e-beam
welding, warm tuning, and chemical treatment
etc.)
18
WP4, T1 FZR SRF Photogun RF Measurement and
Tuning
3D-CAD-Model of the tuning machine used for warm
tuning (to push and pull each cell to the right
frequencies). The special cavity shape required
to build such a machine at FZR.
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.
19
WP4, T1 FZR SRF Photogun Warm Tuning
Field profiles from bead pull measurements.
Before chemical treatment, warm tuning of the
cavities has been carried out in order to obtain
the right frequency and the designed field
profile (equal amplitudes in the three TESLA
cells and 64 in the half-cell).
Photograph of the cavity tuning machine with
integrated bead pull measuring device.
20
WP4, T1 FZR SRF Photogun Cathode Cooling
System
The test of the cathode cooling system has been
succeeded. In the SRF gun, the normal conducting
cathode is inside the SC cavity. With the test
was proofed whether the cathode heat load (from
rf field) will be transported into the liquid N2
cooler. It was found that the cooling system
works well and only a small amount of the heat
(some mW) will be transferred to the SC cavity.

Cathode with heater
Cooling body
Liquid nitrogen reservoir
The cathode cooling system mounted on the test
bench flange. The rf heat load is simulated by an
electrical heater (10 50 W).
21
WP4, T1 FZR SRF Photogun Project Status
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).
22
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

23
WP4, T1 Spectrometer for e-beam

• No News from LOA

24
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.