Introduction to xfel o and charges to the workshop
This presentation is the property of its rightful owner.
Sponsored Links
1 / 19

Introduction to XFEL-O and Charges to the Workshop PowerPoint PPT Presentation


  • 84 Views
  • Uploaded on
  • Presentation posted in: General

Introduction to XFEL-O and Charges to the Workshop. Kwang -Je Kim ANL & U of C& POSTECH Workshop on Sciences Outlook and R&D Issues of X-ray FEL Oscillator February 14-15, 2013 POSCO International Center Pohang, Korea. Free Electron Laser Oscillator.

Download Presentation

Introduction to XFEL-O and Charges to the Workshop

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Introduction to xfel o and charges to the workshop

Introduction to XFEL-O and Charges to the Workshop

Kwang-Je Kim

ANL & U of C& POSTECH

Workshop on Sciences Outlook and R&D Issues of X-ray FEL Oscillator

February 14-15, 2013

POSCO International Center

Pohang, Korea


Free electron laser oscillator

Free Electron Laser Oscillator

  • A low-gain device with high Q optical cavity

  • Optical pulse formed over many electron passes

  • Difficult for x-rays

    • Electron beam qualities

    • High-reflectivity normal incidence mirror

Science Outlook and R&D Issues for an XFELO


X ray fel oscillator xfel o

X-Ray FEL Oscillator (XFEL-O)

An FEL oscillator is feasible in hard x-ray region by using Bragg mirrors

R. Collela and A. Luccio, 1983; KJK, Y. Shvyd’ko, and S. Reiche, 2008

Tuning is possible with a four mirror configuration

R. M.J.Cotterill, (1968) KJK & Y. Shvyd’ko (2009)

A super-conducting linac with a photo-cathode gun can drive an XFELO

3

Science Outlook and R&D Issues for an XFELO


Introduction to xfel o and charges to the workshop

Ginger Simulation of XFELO Spectrum After 500 Passes (Two Diamond Crystal Cavity, 50 mm and 200mm, R. Lindberg)

Science Outlook and R&D Issues for an XFELO


Temporal and spectral e volution of xfelo

Temporal and spectral evolution of XFELO

R.R. Lindberg, K.-J. Kim, Yu. Shvyd’ko, and W.M. Fawley, Phys. Rev. ST-AB. 14, 010701 (2011)

Science Outlook and R&D Issues for an XFELO


An xfelo produces fully coherent temporal as well as transverse x ray pulses

An XFELO produces fully coherent, temporal as well as transverse, x-ray pulses

Science Outlook and R&D Issues for an XFELO


Example parameters

Example Parameters

Electron beam:

Energy 6 GeV

Bunch charge ~ 25-50 pC low intensity

Bunch length (rms)  1 (0.1 ps)  Peak current 20 (100) A

Normalized rms emittance 0.2 (0.3) mm-mr, rms energy spread ~ 210-4

Constant bunch rep rate @ ~1 MHz

Undulator:

Lu= 60 (30) m,lu ~2.0 cm, K=1.0 – 1.5

Optical cavity:

2- or 4- diamond crystals and focusing mirrors

Total round trip reflectivity > 85 (50) %

XFELO output:

5 keV w 25 keV

Bandwidth: Dw/w ~ 1 (5) 10-7; rms pulse length = 500 (80) fs

# photons/pulse ~ 1109

Rep rate ~ a few MHz

(..) indicates short-pulse mode for relaxed tolerances

Science Outlook and R&D Issues for an XFELO

8


Xfelo applications

XFELO applications

High resolution spectroscopy

Inelastic x-ray scattering

Mössbauerspectroscopy

103/pulse, 109/sec Moessbauergs (14.4 keV, 5 neV BW)

X-ray photoemission spectroscopy

Bulk-sensitive Fermi surface study with HX-TR-AR PES

X-ray imaging with nm resolution

Smaller focal spot with the absence of chromatic aberration

Other talks in this workshop

Science Outlook and R&D Issues for an XFELO


An ultimate x ray fel facility

An Ultimate X-Ray FEL Facility

  • A grand facility employing XFELOs and high-gain XFELs can be envisaged in which an XFELO serves as the seed for a high gain amplifier

Science Outlook and R&D Issues for an XFELO


Accelerator technology issues

Accelerator Technology Issues

  • Basic configuration: low emittance gun + SCRF Linac

  • Gun

    • LCLS low charge operation demonstrated that the beam quality requirements for single pulse can be met

    • High rep rate (> MHz) guns have been constructed and are being tested

  • Cost saving R&D in super-conducting linac

    • High Q0 (10101011) to save the refrigerator cost

    • Solid state RF power

  • One or more recirculation passes could reduce the cost

    • Use ERL but in accelerating phase

Science Outlook and R&D Issues for an XFELO


Accelerator technology injector

Accelerator technology: Injector

  • DC gun for ERL(KEK/JAEA, Cornell) and the low frequency RF gun for NGLS will meet the XFELO requirements

C. Papadopoulus, et al., MOPD31

N. Nishimori, et al, WEPD51

Science Outlook and R&D Issues for an XFELO


Introduction to xfel o and charges to the workshop

Science Outlook and R&D Issues for an XFELO


Introduction to xfel o and charges to the workshop

Using ERL loops for additional acceleration: KEK/JAEA project

lrf/2 path-length

changer

6 (7) GeV

3GeV ERL

in the first stage

XFEL-O in 2nd stage

Science Outlook and R&D Issues for an XFELO


Challenges for x ray optical elements

Challenges for X-ray Optical Elements

  • Diamond is best: high reflectivity and thermo-mechanical properties

    • Heat load dynamics: Can DEBragg< 1 meV maintained?

    • Radiation damage issues

  • Stability of optical elements

    • Angular <10 nr & position< 3 mm @ 1 kHz BW

    • Precision stages

  • Surface qualities

    • Reflectivity and wavefront distortion

  • Quality of grazing incidence focusing mirrors

Science Outlook and R&D Issues for an XFELO


Reflectivity of tisncm diamond was measured to be 98 at the aps

Reflectivity of TISNCM* Diamond was measured to be >98% at the APS

*Technological Institute for Superhard Novel Carbon Materials, Russia

Science Outlook and R&D Issues for an XFELO

16


Grazing incidence curved mirror

Grazing Incidence, Curved Mirror

JTEC

Developing a technique combining elastic emission machining (slow) and electrolytic in-process dressing (fast) to fabricate a smooth surface to <nm height error and 0.25 mrad figure error

Issue: large difference in the sagital and meridional depths

Such mirrors are sought after by “every body” in SR business

Other ways of focusing

Curved crystal surface, CRL,..

H. Mimura, et. al.

RSI 79, 083104, 2008

Science Outlook and R&D Issues for an XFELO


Introduction to xfel o and charges to the workshop

Further opportunities for an XFELO: Extreme temporal coherence length from sub-mm km108 m(spontaneous emission limit)!

  • The XFEL-O output pulses are copies of the same circulating intra-cavity pulse

  • The pulse spacing needs to be stable to maintain a good overlap with electron beams: DT < 3 mm

  • If the pulse spacing T can be controlled far more accurately, DT <0.01l/c, the spectrum of XFELO output becomes a comb

  • The extreme-stabilized XFEL-O may establish an x-ray-based length standard and have applications in fundamental physics—quantum gravity, wavefunction collapse of mesoscopic system

Science Outlook and R&D Issues for an XFELO


Introduction to xfel o and charges to the workshop

Cavity stabilization by tying one of the comb lines to a nuclear resonance line(B.W. Adams and K.-J. Kim, to be published)

Find the signal maximum by changing the cavity length ~1 Å and lock to it

Science Outlook and R&D Issues for an XFELO


Charge to workshop

Charge to Workshop

  • Identify the prospects and importance for sciences that can be done by XFELO

  • Are there scientific areas not discussed in this workshop? How can we find them?

  • Identify the technological challenges for constructing an XFELO, in accelerator and in x-ray optics.

  • Can the challenges be addressed by an R&D program, say, for 5 years?

  • Comment on the scientific prospects and technological challenges for an extreme-stabilized XFELO

Science Outlook and R&D Issues for an XFELO


  • Login