W.S. Graves, ASAC Review, Sept 18-19, 2003 Accelerator Overview Goals for proposal Description of...

W.S. Graves, ASAC Review, Sept 18-19, 2003

Accelerator Overview•Goals for proposal

•Description of technical components: injector, linac, compressors, etc.

•Summary of technical challenges

•Elements of R&D program

William S. GravesMIT-Bates Laboratory

Presentation to MIT X-ray laser Accelerator Science Advisory

Committee

September 18-19, 2003


1. Describe an integrated laser laboratory integrating sources that span the visible to x-ray wavelengths.

2. Produce accelerator and laser design for a user facility.

3. Increase the user community’s perception that required accelerator and laser technologies are mature.

Goals for proposal

Three key attributes:1. Many beamlines are planned, each running at 1 kHz or more.

2. Laser wavelengths spanning visible to x-ray are available in a single facility.

3. Seeding for longitudinal coherence at all wavelengths is included in the initial design.


A brief history of the MIT effort

•Spring 2002

D. Moncton approaches R. Milner about the possibility of an x-ray FEL at Bates lab.

•Summer 2002

Workshop held at Bates on the source technologies.

•Spring 2003

Proposal for 4 GeV user facility submitted to NSF. Collaboration meeting held for contributors to proposal.

•Summer 2003

User program committee meets.

•Fall 2003

First accelerator concept review. Today!


1. High repetition rate photoinjector, cathode, drive laser.

2. SRF sections, preferably CW, including 3rd harmonic cavity.

3. Bunch compressors.

4. Electron beam switchyard to undulator halls.

5. Seed lasers, HHG generation.

6. FEL output properties, undulator layout.

Technical Components

Little presentation on x-ray components and diagnostics, or electron beam diagnostics.


Facility layout

0.3 nm 0.1 nm

UV Hall X-ray Hall

Nanometer Hall

SC Linac4 GeV2 GeV1 GeV

1 nm

0.3 nm

100 nm

30 nm

10 nm

10 nm

3 nm

1 nm

Master oscillator

Pump laser

Pump laser

Seed laser

Seed laser

Seed laser

Pump laser

Fiber link synchronization

Injector laser

Undulators

Undulators

Undulators

Future upgrade to 0.1 nm at 8 GeV

SC Linac


Key accelerator elements and issues

Photoinjector

SRF

linac

SRF

linac

Bunch

compress

or

Ebeam

switch

Undulators

Photocathod

e laser

Photocathode laser: Timing and power stability

Photoinjector: Produce low emittance ebeam at 5% duty

factor

Linac: Rf amplitude and phase

Compressor: Produce high peak current ebeam, low CSR.

Switch: Rate, stability

Undulators: Tunability, variable length

Seed lasers: HHG generation, stable operation, timing

Seed laser


Photoinjector

3 cell pulsed room temperature cavity operating at 10 kHz

-presentation by Manouchehr Farkhondeh


Direct diode-pumped, fiber amplifier

-presentation by Franz Kaertner

Yb:fiber amplifierIPG-Photonics

20ps, 10J, 1-10 kHz@ 1064 nm

4th-Harmonic

20ps, 1J, 1-10 kHz@266 nm

Yb:YAG, 1ps

rep. Rate100 MHz

Pulse Selector

Temporal: Flat-top shaped

Photoinjector drive laser

Acousto-OpticProgrammablePulse Shaper

(Dazzler,Fastlight)


RF and cryoplant

-presentation by Townsend Zwart


Beam dynamics, bunch compression

-presentation by Fuhua Wang


Electron beam switchyard

100 20 30 40 50 m

RF/Ferrite switch, 5 mr

Septum Magnet, 150 mr

Dipole Magnet, 350 mr

Undulator

Undulator, Beam Line Hall

Accelerator

10 20 30

-presentation by Jan van der Laan


Laser seeding

Noble Gas Jet (He, Ne, Ar, Kr)

100 J - 1 mJ

@ 800 nm

XUV @ 3 – 30 nm

= 10-8 - 10-5

Recombination

Propagation

-Wb

XUV

En

erg

y

x

b

0

Laser electric field

Ionization)(17.30 pbc UWN

Cut-off Harmonic:

-presentation by Franz Kaertner


FEL output properties

0 10 20 30 40 500

0.5

1

1.5

2

Time (fs)

Pow

er (

GW

)

0 10 20 30 40 500

0.5

1

1.5

2

Time (fs)

Pow

er (

GW

)

0 10 20 30 40 500

0.5

1

1.5

2

Time (fs)

Pow

er (

GW

)

0 10 20 30 40 500

0.5

1

1.5

2

Time (fs)

Pow

er (

GW

)

0 10 20 30 40 500

1

2

3

4

5

6

7

8

Time (fs)

Pow

er (

GW

)

0 10 20 30 40 500

1

2

3

4

5

6

7

8

Time (fs)

Pow

er (

GW

)

0.2995 0.3 0.3005 0.3010

200

400

600

800

1000

Wavelength (nm)

Pow

er (

kW/b

in)

0.2995 0.3 0.3005 0.3010

200

400

600

800

1000

Wavelength (nm)

Pow

er (

kW/b

in)

0.2995 0.3 0.3005 0.3010

100

200

300

400

500

Wavelength (nm)

Pow

er (

MW

/bin

)

0.2995 0.3 0.3005 0.3010

100

200

300

400

500

Wavelength (nm)

Pow

er (

MW

/bin

)

0.2995 0.3 0.3005 0.3010

100

200

300

400

500

Wavelength (nm)

Pow

er (

kW/b

in)

0.2995 0.3 0.3005 0.3010

100

200

300

400

500

Wavelength (nm)

Pow

er (

kW/b

in)

Seeding for short pulses

Seeding for narrow bandwidth

SASE


1. Achieve ~10 fs timing synchronization between FEL output, seed lasers, and pump-probe lasers.

2. Necessary RF phase and amplitude stability for timing above.

3. Stability in energy per pulse, timing, and pointing appropriate for a user facility.

4. Reduced power consumption for CW operation.

5. Reliable laser seed generation including tunability and stability.

6. Development of fast RF or ferrite switches necessary to deliver beam to multiple undulators.

7. Development of a high repetition rate, high brightness photoinjector.

8. Development of tunable undulators. Matching of undulator resonance. Rapid orbit correction at different wavelengths.

9. Electron beam diagnostics.

10.Coherent photon beam diagnostics.

Technical challenges


NSF referee reports

•Proposal covers very large range of activities…difficult for individuals to review.

•Several referees recommend stronger R&D program.

•Doubts expressed about maturity of technologies.

•Reviews and our response to specific issues will be discussed Fri a.m.

Provide your input and feedback on the reviews and our response. Give advice on R&D issues and effort level.

Is substantial R&D necessary before proceeding to design stage? Identify best path forward.

MIT remains committed to building

an x-ray laser lab


R&D program at Bates

Demonstrate some of the key technologies at lower energy including

1. Seeding with ultrashort HHG pulses

2. Development of tunable seed laser

3. Cascaded HGHG FEL output

4. Timing synchronization of FEL, seed, and pump lasers below 100 fs

Identify key R&D issues.


Original schedule


Concluding remarks

•Concept is still at an early stage.

•Simulations of separate systems (injector, linac, switchyard, FEL) are underway, but not yet connected as a start-to-end effort.

•This review should assess the directions we are taking rather more than the initial results.

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