1. Materials Research in the LERF User Labs
Michael J. Kelley
College of William & Mary and Jefferson Lab

2. Materials R&D Lab Concept and Mission
Precise energy delivery for materials modifications
- Wavelength, location, fluence, time, etc.
Unique light sources, some deployable
- FEL (IR, UV), ps lasers, ns lasers, UV lamps
Application devices
- Laser micromachining system, Pulsed laser deposition system
What has been/could be done
- Polymer surface chemical modification – synthetics, renewables
- Laser polishing, Laser nitriding, PLD for organics

5. Sharp surface roughness enhances
magnetic field concentration, promoting energy loss
Chen Xu dissertation

7. Light BCP
AFM
PSD
Liang Zhao
dissertation

8. Why Nitride the Niobium Surface?
Presently Nb SRF cavities operate near 1.9 K, well (and expensively) below the 4.2 K atmospheric boiling point of liquid He.
Forming the active interior surface from  NbN (Tc  17 K) vs the present Niobium (Tc  9.2 K), would reduce cryogenics cost and simplify the engineering design.
Enable 4.2 K operation
Conventional furnace nitriding does not produce superconducting delta phase NbN.

9. Nitriding Experiment Laser parameters: Wavelength : 1064 nm
Repetition rate : 15 – 30 KHz
Pulse width : 15 ns
Fluence : 1.1 – 4 J/cm2
Treatment parameters:
N2 pressure : 500 – 625 torr
Target rotation : 9 rpm
No. of pulses overlap/area
on each circle :
Raja Singaravelu dissertation

10. Laser heating : Simulation
Raja Singaravelu
dissertation
Surface temperature profile for niobium for various
laser fluences (for single pulse – pulse width = 15 ns)

11. X-Ray Diffraction
Raja Singaravelu dissertation

12. Polymer PLD experiment
Cyclic Olefin Copolymer - COC
Uses:
High transparency and gloss
High heat resistance upto 1780 C
Resists acids and alkalis
Excellent moisture and aroma barrier
Excellent biocompatibility
n,m = repeat units
R1, R2, R3 = -CnH2n+1
Free electron laser parameters:
60Hz, 250 us, 4MHz, 3.4 m
Raja Singaravelu dissertation

14. that use our capabilities
We seek opportunities
for collaborations
that use our capabilities

15. Special thanks to the students who did the work
Lopamudra Das – W&M
Raja Singaravelu – ODU
Liang Zhao – W&M
Zhengmao Zhu – W&M