PITZ overview: the PITZ portfolio

PITZ overview: the PITZ portfolio

Frank Stephan for the PITZ teamContent:• The PITZ collaboration• A) photo injector R&D in ST3 “ps/fs electron and photon beams”

• R&D program agreed with and co-funded by XFEL• Progress on generating 3D ellipsoidal beams• Operation experience with Gun 4.6 • Gun quad corrector studies• Design of gun 5• Bunch shaping with dielectric lined waveguides• Generation of THz radiation

• B) Plasma Activities @ PITZ in ST4 “Novel acceleration concepts”• Beam driven plasma acceleration activities:

- Self modulation experiments- Transformer ratio experiments

• Laboratory Astrophysics preparations

See scientific highlight talk

Frank Stephan for the PITZ team | PITZ overview: the PITZ portfolio | LAOLA workshop | 27. 6. 2017 |

> Founding partners of PITZ:

DESY, HH & Z (leading institute)

HZB (BESSY) (A. Jankowiak): magnets, vacuum

MBI (S. Eisebitt): cathode laser

TU Darmstadt (TEMF, T. Weiland, H. DeGersem): simulations

> Other national partners: Hamburg university :

- most PhD students; - HGF-Vernetzungsfond; - generation of short pulses- plasma experiments

HZDR: - BMBF-PC-laser-project between MBI, DESY and HZDR, unitl ~2009; - collaboration between HZB, HZDR, MBI andDESY in SC-gun-cluster

> International partners: IAP Nizhny Novgorod + JINR Dubna :

3D elliptical laser pulses, THz radiation

INFN Frascati + Uni Roma II (L. Palumbo, M. Ferrario): TDS and E-meter pre-studies

INFN Milano (C. Pagani): photocathodes

INR Troitsk (L. Kravchuk): CDS, TDS, Gun5

INRNE Sofia (D. Tonev, G. Asova): EMSY + personnel

LAL Orsay (A. Stocchi): HEDA1 + HEDA2

STFC Daresbury (S. Smith, B. Militsyn): phasespace tomography

Thailand Center of Excellence in Physics(T. Vilaithong, Ch. Thongbai): personnel

YERPHI (V. Nikoghosyan) + CANDLE (V. Tsakanov, B. Grigoryan), Yerevan : personnel

PITZ Collaboration Partners ( formal contract signed )


R&D program agreed with and co-funded by XFEL

> Funding is planned from ~mid 2017 on and current planning horizon is until 2021 , yearly update (no major changes)

> A) From XFEL operations budget:- Support of XFEL operation : 4 weeks of PITZ operation for dedicated measurements

+ 1 physicist for working on improving pulsed guns - e.g. gun quad corrector studies, different operation modes (charges, bunch length), time resolved and emittance

measurements , emission studies, test of unified procedures , diagnostics, stabilization , llrf and laser components, …

- Option ( on request, ~1 year in advance): gun construction and conditioning (16 weeks)

> B) From XFEL R&D budget:- Advanced photo cathode laser shapes: 2 weeks of PITZ operation for generic R&D on

ellipsoidal electron bunches- ultimate beam quality at different cathode gradients, … e.g. measurements (emitt., LPS, µ-bunching ) for different

laser shapes

- Developments towards CW guns : 4 weeks of PITZ operation for basic CW gun research (e.g. beam dynamics at CW gun gradients , green cathodes ) + 1 physicist investigating a 216 MHz NC CW gun and supporting SRF gun activity

- Experimental beam dynamics studies at CW gun gradients e.g. emission properties, thermal emittance , optimumbeam quality using different laser shapes , …

- Studies towards green cathodes dark current, emission properties, thermal emittance, optimum beam quality usingdifferent laser shapes and gun gradients, …

- Physical design of 216 MHz NC CW RF gun + buncher system RF + beam dynamics simulations, beamlineoptimization, …


Under operation at PITZ:> Hamamatsu SLM> Laser integrated into PITZ laser beam line> Synchronization with RF realized with uTCA> Beam shaping studies begun (SLM masks)> Electron beam measurements with regular

shaped ELLA pulses (starting Dec.2016now)

Progress on generating 3D ellipsoidal beams with the laser systemfrom the Institute of Applied Physics (IAP, Nizhny No vgorod)

Spatial Light Modulator ( SLM) based pulse shaper

Manipulations on spectrum of a linear chirped pulseLaser pulse shape reconstruction from spectrograph measurements

F2

M(Ω)

F1f f f f

Upcoming upgrade at PITZ:> Pharos-20W-1MHz frontend laser delivered should solve most of laser related problems > 3D volume Bragg gating (DSF funds) postdoc will start 1.8.2017

X

Tim

e

Recent electron beam measurements at PITZ (0.5nC)

E-beam TDS-streaked~parabolic shape

Issues limiting current performance:> Laser beam transport (transverse size)> Oscillator + disc amplifier performance:

Synchronization (<10kHz) Stability (pointing and intensity jitter, long term

drift) Spectrum pulse too short

> Pockels cell (contrast, flatness)> …

, , ∙ , 1.06

ELLA laser at VC2


Operation experience with Gun 4.6

PMT

e-det

PG

pump

dir.cpl.

valvestemp.

PMT PMT

PMT

PMTse-det e-det

IR IR

PMT

IGP

IGP

IGPIGP

dir.cpl.

dir.cpl. dir.cpl.

dir.cpl.

temp.

temp.

temp.

temp.

PMT – Photomultiplier tube

e-det – Electron detector

IR – Infrared sensor

IGP – Ion getter pump

(pressure reading)

PG – Pressure gauge

radiuschanged

nose removed

air air

> Features of the Gun 4.6 setup Gun 4.6 with new type of cathode spring holder

design (watchband-reloaded)

two conditioned DESY-type windows for the 2-window setup (as in 2011)

T-Combiner with optimized RF design for best window positioning for reflections

> Operation at 6.5 MW, 650µs, 10Hz: Cathode spring design and

2 RF vacuum window solution seem to work reliably ! Problem with inserting cathode probably related to

malfunctioning/damage/misalignment of z-manipulator NEXT: - Gun4.6 quick restart , run until Oct.2017 ( XFEL)

- then Gun4.5 with 2 Thales windows


Gun quad corrector studies (measurements 2017)• BSA = 1.2 mm• Charge = 500 pC• Gun power = 6.5 MW

• Booster power = 3 MW• Gaussian Laser temporal profile: ~11.5 ps• Bunch length (TDS) = 15.8 ps

Machine parameters:

No Gun Quads applied : Gun Q1 = 0A / Gun.Q2 = 0A With Gun Quads : Gun Q1 = -0.6A / Gun.Q2 = -0.5A

Transverse beam profile

X phase space

Y phase space

Transverse beam profile

X phase space

Y phase space

• The gun quad currents were selected to deliver the most round beam spot at High1Scr1 and High1Scr4 simultaneously

No Gun Quads With Gun Quads

x y xy x y xy

Emittance, mm·mrad

1.11 0.78 0.93 0.82 0.84 0.83

Beam RMS size, mm

0.46 0.32 0.28 0.32

α -0.99 0.39 0.06 -0.01

β 4.85 4.37 3.18 3.24

γ 0.41 0.26 0.32 0.31

No Gun Quads With Gun Quads

“rounder” and smaller emittance!

“rounder” beam

X&Y numbersare close


> Gun 5 new features (see V. Paramonov et al., NIM A 854 (2017) 113-126.):

includes RF probe fine control of RF stability, allows symmetric power coupler (2 input arms)

improved water cooling and reduced deformation over RF pulse more reliable operation at high duty cycle

improved cell geometry reduced RF heating & surface field strength

Gun 5 for higher stability & reliability in technic al design

NX10I-DEAS

test piece

Technical design ongoing and experiments on test pieces started


First Bunch Shaping Experiments with DLW at PITZ> In collaboration with CFEL (F. Lemery) and APC FNAL (P. Piot)

F. Lemery et al., Experimental demonstration of ballistic bunching with dielectric-lined waveguides at PITZ, IPAC 2017, WEPAB122

Measured Longitudinal Phase Space

E-beam current profile without (blue trace) with DLW (red trace), λ=1.03 mm; The peaks are consistent with the wavelength of the structure 3.3 ps.


> Idea: Accelerator based THz (1) & electron diffraction source (2) for XFEL users

Tunable THz source for pump-probe experiments at XFE L + High flux e - diffraction source based on PITZ prototype

(2) Femtosecond e - diffractionv.s. X-ray: sub-pm wavelength, good spatial resolution ~106 higher scattering cross section, good for

thin or low density samplev.s. other MeV electron diffraction source: higher rep. rate & higher flux; trade flux for higher transverse coherence;new methodology: XFEL pump, electron probe;

PITZ gun

L-band linac(booster or buncher)

Sub-100 fse- diffraction

User sample chamber

>15 meter

(1) Linac based THz sourceAttractive features:• provides high power (high field)

Possible options:• Undulator SASE THz FEL• Other, e.g. transition, diffraction, synchrotron, edge radiation

Challenges:• Phase locking (CEP stability) for field driven dynamics• Short bunches (bunch compression) for single-cycle radiation

Simulated energy of the radiation pulse

100 µm (3 THz)

~3 mJsynchronized

with XFEL train structure

Current status:• First electron beam measurements for SASE THz FEL option

were done• CTR experiment station is under realization• Seeding options under study

Basic PITZ parameters:• bunch length: sub ps to 22 ps• bunch charge: sub pC to > 5 nC• max Pz ~ 24MeV/c• pulse train structure similar to XFEL

Complementary tool for XFEL

user to get a full picture of the

ultrafast atomic world!

• tunability of radiation• polarization control• clean production of

the radiation invacuum

H. QianM. Krasilnikov


> Beam driven plasma acceleration activities:

Self modulation experiments

High transformer ratio experiments

Highlight talk


Laboratory Astrophysics

> Idea: find parameter scaling so that astrophysical phenomena can be investigated in the laboratory

> Currently: DESY Strategy Fund project to demonstrate Bell‘s instability

Collaboration between 3 different divisions: THAT (Martin Pohl), PITZ (Frank Stephan) and FLA (Jens Osterhoff)

Simulation study / exploring experimental possibilities; best case: first experimentsin 2018

> Bell‘s instability: Amplification of magnetic fields in a plasma, induced by cosmic rays

> This could be part of the mechanism of cosmic particle accelerators


Current Work

> 1) PIC simulations for laboratory conditions

Preliminary results: Need

• Low plasma density (1013 or less)• Low beam energy (<10 MeV)• Long electron bunches (best DC) with at least mA current

> 2) Study if these conditions can be provided by PITZ

> So far: challenging, but no show stoppers found yet

extensive simulationshave started and willbe continued


Summary & Outlook

> There is a very rich and scientifically and technically interesting program ongoing at PITZ, with substantial support from XFEL.

> Several topics are of high relevance for different groups, at DESY andworldwide.

> Largest part of activity is in ST3: fs/ps electron and photon beams

> But also significant activity in beam driven plasma acceleration seehighlight talk

> Laboratory Astrophysics experiments are under preparation

PITZ overview: the PITZ portfolio

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