Commissioning plan for UED@ASTA

Renkai Li

5/20/2014

ALD UED@ASTA Review

2

Outline

• Pre-operation preparation

• Commissioning plan

- Machine operation and e-beam characterization

- Transverse overlap of laser and e-beam

- Temporal overlap of laser and e-beam

• Summary

3

Pre-operation preparation

• Checklist

- Safety

- Training

- Trigger and timing

- Equipment protection

- Modulator, klystron, LL and high power rf

- Alignment

- rf gun

- Laser

- Magnets and power suppliers

- Motors/actuators

- Cameras

- Diagnostics

- Data management

- Software

UED@ASTA preparation checklist

4

Pump-probe control and data acquisition

control

delay stage

Shutter S1/S2

acquire

photodiode D1/D2

Virtual pump Camera C2

EMCCD

Computertransfer

To be built and tested off-line.

Sample holder

control trigger

1D1

S1

e-beam

BS1D2

sample

1C2S2

delay stage

EMCCD

Computer

> 100 M/s

gun

5

Commissioning plan

• Laser optics installed by July 15th

• Beamline installation July 15th – July 31th

• Aim to run e-beams starting from August 1st w/o sample chamber

6

Machine operation and e-beam characterization

• Most tasks ready by August 1st

- Safety

- Training

- Trigger and timing

- Equipment protection

- Modulator, klystron, LL and high power rf

- Alignment

- rf gun

- Laser

- Magnets and power suppliers

- Motors/actuators

- Cameras

- Diagnostics

- Data management

- Software

August 1st – 15th

• Operation of the machine

• e-beam energy, charge, spot size

• Stability of e-beam parameters

• shot-to-shot fluctuation

• long-term (a few hours) stability

August 15th -

• Sample holder control

• laser and e-beam transverse overlap

• laser and e-beam temporal overlap

7

Transverse laser and e-beam overlap

aperture (4-5 mm diameter)

steering coils

He-Ne

laser

e-beam

screencamera

stage

Sample holder at UCLA

screen

SiN window (broken)

SiN window

8

Temporal laser and e-beam overlap

Steps to find time-zero

1) Fast photodiode D1 and D2 (< 100 ps or 3 cm)

2) Measure the rest of optical path length (~1 cm)

3) time-of-flight of the e-beam (from simulation)

4) Ultrafast plasma lensing effect (<1 ps)

400 fs step size

J. R. Dwyer et al., Phil. Trans. R. Soc. A 364, 741 (2006)H. Park et al., RSI 76, 083905 (2005)

2000 mesh TEM Grid-8 ps -4 ps 0 ps

4 ps 8 ps 12 ps

16 ps 20 ps 28 ps3 MeV beam up to ~50 J/cm2 L0

LC. M. Scoby et al., dx.doi.org/10.1016/j.ultramic.2012.07.015

9

Summary

• Pre-operation preparation (checklist, now – August 1st)

• Machine operation / e-beam characterization (August 1st - )

• Transverse overlap of laser and e-beam

• Temporal overlap of laser and e-beam

• Experiment using samples with ultrafast (100 fs) response

Thank you!