10 kHz 40W Ti:sapphire regenerative ring amplifierIsao MATSUSHIMA, Hidehiko YASHIRO, Toshihisa TOMIENational Institute of Advanced Industrial Science and Technology (AIST), Japan Laser system for laser-plasma X-ray source *This study was partly financially supported by the Budget for Nuclear Research of the Ministry of Education, Culture, Sports, Science and Technology, based on screening and counseling by the Atomic Energy Commission.

Laser-Plasma X-ray Source

X-ray, λ~nm, <nsblight point source

TargetPlasma

High Temperature<100μmϕ,

Ionization >ps,

Laser

>>mJ, ~10μmϕps<τ<ns>1011 W/cm2

*EUPS; extreme ultraviolet (EUV) excited photoelectron spectroscopy*EUV source for defect inspection of multi-layered mask blanks*EUV lithography*X-ray microscopy of living cells

multi kHz repetition-rate is required for high throughput

6789

1

2

3

4

5

6789

10

2

Pulse Energy (mJ)

5 6 7 8 91

2 3 4 5 6 7 8 910

Repetition Rate (kHz)

CLIA

Brown U U Tokyo

AIST

AISTU Deraware

Max-Born

U ColoradoFS-10

Single Stage UncompressSingle Stage Compressed

Multi-Stage CompressedMulti-Stage Uncompress

commercial Ti:S

MOPA Ti:S

FiberLaser

Our Target Area

We need Multi-kHz Multi-mJ Laser

Cryogenic Cooling reduce thermal lens

ω2T4 =

2λ fT

π⎛⎝⎜

⎞⎠⎟

2 2 f − L / 22 fT − L / 2

L / 22 f + 2 fT − L / 2

⎛⎝⎜

⎞⎠⎟

Resonator mode beam radius at the rod

Pump fT 2ω2T

0W ∞ 780 μm

180W 2.2 m 880 μm

fT f=1m

L = 3.6 m

2ω2T

Resonator Design

70

60

50

40

30

20

Extraction efficiency (%)

3025201510Loss (%)

3Es

2Es

1Es 0.5Es

1.5Es

High Efficiency

Pump LaserAO2/G (PowerLase) ×2

High repetition rate : 10 kHz High pulse energy : 8mJ x 2

Good beam quality : M2=23.5

180 W Pump40 W output beam quality M2 < 1.2 @35W, 58 fs (4% power)Before compression4 mJ/pulse10kHzTi:sapphire Regen Amp

26 W 40 W

Full power compression

Thermal distortion of compressor grating12 mmφ clear aperture

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r05080303r05083111M2 =1.8

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r05083112

Air Cooled Grating

Without Cooling With Cooling

Small Power <1W

20W after compression

10kHz Rep-rate Ti:Sap Regen AmpSummary

180 W Pump40 W output beam quality M2 < 1.2 @35W, 58 fs (4% power)4 mJ/pulse

after compression

26 W

Air Cooled Grating20 W M2~1.8, 80fs30 W

40 Wcompression