Status of the JLab IR/UV Upgrade fileThomas Jefferson National Accelerator Facility FEL Status of...

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Thomas Jefferson National Accelerator FacilityFEL

Status of the JLab IR/UV Upgrade

George R. Neil, C. Behre, S. V. Benson, G. Biallas, J. Boyce, L.A. Dillon-Townes, D. Douglas, H. F. Dylla, R. Evans, A. Grippo, D.

Gruber, J. Gubeli, C. Hernandez-Garcia, K. Jordan, M. J. Kelley, L. Merminga, J. Mammosser, N. Nishimimori, J. Preble, M. Shinn,

T. Siggins, R. Walker, G. P. Williams, and S. Zhang

Jefferson LabNewport News, Virginia

LPC Newport News March 9, 2005



10 kW IR and 1 kW UV

• 100 W broadband 2 to 50 cm-1

• 10 kW average power, 1–14 microns• 3 kW average power, .3 to 1 micron• all 400 femtosecond FW @ 75 MHz

JLab FEL Upgrade Status

. THz system installed and ready to begin user experiments

. IR Upgrade FEL at JLab starting up at 10 kW. Characterization has begun : 10 kW average power lasing achieved at 6

microns. Lased at moderate powers at 2.8 - 3microns with broadband mirrors. User experiments getting ready; have provided alignment beam into Lab 1

. UV installation this year . User experiments late next fall

. Some setbacks: lost some gradient capability in linac; may not be able to make 1 micron at full power or UV lasing on fundamental until replacement cryomodule is ready. User program will continue:

. Third harmonic 1 micron lasing

. 700 nm lasing and doubled



IR Upgrade Specifications• Average Power > 10,000 W. Wavelength range 1 to 14 µm . Micropulse energy > 100 µJ, in pulse train 50 µs to CW, arbitrary prf. Micropulse length ~0.1-2 ps FWHM (adjustable). PRF 74.85 MHz ÷ 2x down to 4.68 MHz. Bandwidth ~ 0.2–3 % (always Fourier transform limited!). Position/Angle jitter < 100 um, 10 µrad . Polarization linear, > 1000:1. Transverse mode < 2x diffraction limit. Gaussian profile

. Beam dia. at lab 2 - 6 cm, wavelength dependent





Performance with Variable Gap PM Wiggler

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100

2 4 6 8 10

Gain and Power vs. Wavelength, Variable Gap

Power(5 mA)Power(8 mA)

Gain(5 mA)Gain(8 mA)

Pow

er(k

W) G

ain(%)

Wavelength(µm)

Minimum beam energy=80 MeV, Energy <160 MeV. Energy spread constant

UV Upgrade Performance: Installation next summer

UV Upgrade Power and Gain



0

1

2

0

100

200

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

3

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5

300

400

500

Power(kW)

Gain(%)Pow

er(k

W) G

ain(%)

Wavelength(µm)

•Tunable pulse energy to saturate electronic transitions

•Drive non-linear field effects

•High rep rate for S/N: e.g., molecular beams, gas phase



1 10 100 1000 100001E-121E-111E-101E-91E-81E-71E-61E-51E-41E-30.010.1

110

1001000

10000

Energy (meV)

Flux

(Wat

ts/c

m-1)

Wavenumbers (cm-1)

1 10 100 1000

JLab THz

Synchrotrons

Globar

JLab FEL

Table-top sub-ps lasers

FEL proof of principle:Neil et al. Phys. Rev.Letts 84, 662 (2000)

THz proof of principle:Carr, Martin, McKinney, Neil, Jordan & WilliamsNature 420, 153 (2002)

High power THz with sub-picosecond pulses is produced parasitically from electron beam

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

3000 3050 3100 3150 3200 3250 3300 3350 3400

0

2

4

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8

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12

-25 -20 -15 -10 -5 0 5

IR Demo measured bandwidth varies as a function of optical cavity length

Wavelength (nm)

Detuning (microns)

Pow

er

c

a

b

Pow

er

a

b

cDetuning curve:cavity synchronism

Bandwidth is Fourierlimited at each pulse length;< 40 optical periods at broadest!



Many studies use ultrashort pulses: IR Demo autocorrelation data

190 fs RMS:10 periods!





Terahertz beamline transports visible to 5 mm wavelengths to user lab in vacuum

FEL Vault Ceiling

FEL Vault

FEL Lab 3

Electron beamline Synchrotron and edge radiation light port



See G. Williams, MM4.3

JFEL THz Beamline Calculated Optical Beam Patterns

-3x10-2 m

-2

-1

0

1

2

3

Ver

tical

Pos

ition

-30mm -20 -10 0 10 20 30

Horizontal Position

-4x10-2 m

-2

0

2

4

Ver

tical

Pos

ition

-40mm -20 0 20 40

Horizontal Position

-1.0x10-1 m

-0.5

0.0

0.5

1.0

Ver

tical

Pos

ition

-100mm -50 0 50 100

Horizontal Position

F1

M1

372M2 M3

F2

M4 F3

3x10-2 m

2

1

0

-1

-2

-3

Ver

tical

Pos

ition

20mm100-10-20

Horizontal Position

-3x10-2 m

-2

-1

0

1

2

3

Ver

tical

Pos

ition

-30mm -20 -10 0 10 20 30

Horizontal Position

-1.0x10-1 m

-0.5

0.0

0.5

1.0

Ver

tical

Pos

ition

-100mm -50 0 50 100

Horizontal Position

200x200mm

200x200mm

120x120mm

60x60mm

60x60mm

60x60mm

Special thanks to Oleg Chubar,Paul Dumas.

Lasing Capability – IR Upgrade• We have several sets of high power mirrors capable of

multi-kW but these are narrow band. 6 microns, 2.8 microns, 1 microns, (1.6 microns,

(2.2 microns on order). We also have hole outcouplers and broadband mirrors

for lasing from 1 to 10 microns at ~ 50 W output. Instantaneous tuning is limited only by wiggler (K2 goes

from ~0.7 to 1.1. Alignment light has been brought up to Lab 1 and the

facility is essentially ready for User experiments



Capability projections – the bad news• We have several ailing srf cavities that have reduced our

energy capability. This will negatively impact the wavelength and power we can achieve

. Exact performance limits are not known at this time; a number of possible approaches and fixes are under investigation; we will know more in the next few weeks

. Additional srf modules may be available in June (standard design) and September (high gradient)

. We also have additional wigglers under procurement and the option of doubling and tripling the FEL output as well as lasing on the third harmonic

. The following slides broadly summarize our expectations; low power means 10’s to a few hundred W, high power means multiple kW



Projected energy available

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2005 Month

Ener

gy (M

eV)

Minimum ExpectedMaximum Expected

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec



Energy requirements for specific programs

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01234567Wavelength (microns)

Ener

gy (M

eV)

Low PowerHigh Power



Lasing Capability – IR Upgrade





Future plans – UV Upgrade

Summary• JLab Upgrade FEL is coming on line as a user facility with

THz, IR, and (soon) UV light Broadly tunableSub-picosecond pulsesExcellent beam qualityUnmatched power, pulse energies(also have conventional lasers synchronized with FEL)

We are about ready to put first IR light into a User Lab

• The capabilities of this facility will gradually be increasing over the next year in terms of short wavelength operation and higher power capability



The work discussed was performed by the FEL Team:

C. P. Behre, S. V. Benson, M. E. Bevins, G. Biallas, J. Boyce, W. Chronis, J. L. Coleman, L.A. Dillon-Townes, D. Douglas, H. F. Dylla, R. Evans, A. Grippo, D. Gruber, J. F. Gubeli, D. G. Hardy, C. Hernandez-Garcia, R. Hiatt, K. Jordan, L. Merminga, J. Mammosser, G. R. Neil, J. Preble, R. Rimmer, H. Rutt, M.D. Shinn, T. Siggins, H. Toyokawa, D. Waldman, R. Walker, G. Williams, N. Wilson, M. Wiseman, B. Yunn, and S. Zhang



With the help of lots of others at JLab

This work supported by the Office of Naval Research, the Joint Technology Office, the Commonwealth of Virginia, the Air Force Research Laboratory, and by DOE Contract DE-AC05-84ER40150.





Spreadsheet Model Predictions for EM Wiggler

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Gain and Power vs. Wavelength, EM Wiggler

Power(5 mA)Power(8 mA)

Gain(5 mA)Gain(8 mA)

Pow

er(k

W) G

ain(%)

Wavelength(µm)

14 kW at 1 µm

No absorption in mirrors assumed in these calculations. Minimum energy=70 MeV, Max K=1.115. Energy spread constant. Can’t guarantee operation longer than 4 µm.

Status of the JLab IR/UV Upgrade fileThomas Jefferson National Accelerator Facility FEL Status of...

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