Status of the Visible-Infrared SASE Amplifier

(VISA@800nm)

 

 

Aaron Tremaine

 

 

 

Collaborating Institutions:

 

BNL: M. Babzien, I. Ben-Zvi, E. Johnson,

R. Malone, G. Rakowsky, J. Skaritka, X.J.Wang, V. Yakimenko

SLAC: R. Carr, M. Cornacchia, H.-D. Nuhn,

L. Klaisner, R. Ruland

UCLA:P. Frigola, A. Murokh, P. Musumeci,

C. Pellegrini, J. Rosenzweig

LANL: D. Nguyen

LLNL: K.A. Van Bibber, G. LeSage, J.M. Hill,

A.Toor

 

 

 

 

Goals and Strategy

 

 

 

Study Self-Amplified Spontaneous Emission (SASE) in collective instability regime

-Designed for saturation

-, electron beam micro-bunching directly related to SASE FEL gain mechanism

-Needed for very short wavelength FELs

-Compare data with SASE FEL codes

-Use of many optical diagnostics

 

Using a strong focusing 4m (4-1m sections) planar undulator

--function of 30 cm

-Must be careful of random walk-off

-Alignment to <30mm

 

Electron beam needed has stringent requirements

-Using and modifying the ATF at BNL

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

 

 

 

 

 

 

 

 

 


 

 


 


Trajectories of e-beam relative to alignment laser


Alignment laser was within 300mm of undulator axis

After this alignment, alignment laser to within 30mm


Detector Signal vs. Charge

 


Used steering magnets to place e-beam <75mm of alignment laser

Nonlinear detector signal vs. charge indicates gain

Large acceptance angle to detector

@240pC within experimental solid angle

@240pC within coherent angle

 

and

 

Using Genesis gives agreement with data w/

 

 

Future Measurements

 

 

1. Power/Energy vs. distance along undulator

Exponential gain

-use pop-ins, detector

2. Micro-Bunching of electron beam

-Coherent Transition Radiation (CTR)

3. Frequency spectrum, (800nm+h.h.)

-monochromator, spectrometer

4. Fluctuations/statistics

5. Angular Spectrum

-cameras

6. Electron Beam vs. distance along undulator

-Yag screens, cameras along undulator

7. Time resolution, spectrum (50 fs resolution)

-Frequency Resolved Optical Gating (FROG)

8. Put chirp in e-beam

 

We will need to operate into the next fiscal year

 

 

 

 

 

Summary

 

 

Undulator characterization finished Nov-Dec 99

 

1st run day Mid January

-Have had two shutdowns for interferometric alignment. 2.5 weeks offline/interferometric alignment.

 

Saw gain

 

Presently-Interferometric alignment of undulator and alignment laser to within tolerances

 

Move towards the more sophisticated radiation diagnostics available