Laser machining of explosives

Patent · Sat Jan 01 00:00:00 EST 2000

OSTI ID:873394

Perry, Michael D ^[1]; Stuart, Brent C ^[2]; Banks, Paul S ^[1]; Myers, Booth R ^[1]; Sefcik, Joseph A ^[3]

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1. Livermore, CA
2. Fremont, CA
3. Tracy, CA

The invention consists of a method for machining (cutting, drilling, sculpting) of explosives (e.g., TNT, TATB, PETN, RDX, etc.). By using pulses of a duration in the range of 5 femtoseconds to 50 picoseconds, extremely precise and rapid machining can be achieved with essentially no heat or shock affected zone. In this method, material is removed by a nonthermal mechanism. A combination of multiphoton and collisional ionization creates a critical density plasma in a time scale much shorter than electron kinetic energy is transferred to the lattice. The resulting plasma is far from thermal equilibrium. The material is in essence converted from its initial solid-state directly into a fully ionized plasma on a time scale too short for thermal equilibrium to be established with the lattice. As a result, there is negligible heat conduction beyond the region removed resulting in negligible thermal stress or shock to the material beyond a few microns from the laser machined surface. Hydrodynamic expansion of the plasma eliminates the need for any ancillary techniques to remove material and produces extremely high quality machined surfaces. There is no detonation or deflagration of the explosive in the process and the material which is removed is rendered inert.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• DOE Contract Number: W-7405-ENG-48
• Assignee: Regents of University of California (Oakland, CA)
• Patent Number(s): US 6150630
• OSTI ID: 873394
• Country of Publication: United States
• Language: English

Related Subjects

laser
machining
explosives
consists
method
cutting
drilling
sculpting
tnt
tatb
petn
rdx
etc
pulses
duration
range
femtoseconds
50
picoseconds
extremely
precise
rapid
achieved
essentially
heat
shock
affected
zone
material
removed
nonthermal
mechanism
combination
multiphoton
collisional
ionization
creates
critical
density
plasma
time
scale
shorter
electron
kinetic
energy
transferred
lattice
resulting
thermal
equilibrium
essence
converted
initial
solid-state
directly
ionized
established
result
negligible
conduction
region
stress
microns
machined
surface
hydrodynamic
expansion
eliminates
ancillary
techniques
remove
produces
quality
surfaces
detonation
deflagration
explosive
process
rendered
inert
affected zone
heat conduction
density plasma
thermal stress
kinetic energy
critical density
thermal equilibrium
ionized plasma
resulting plasma
produces extreme
laser machining
move material
machined surface
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