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Title: Laser machining of explosives

Abstract

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.

Inventors:
 [1];  [2];  [1];  [1];  [3]
  1. Livermore, CA
  2. Fremont, CA
  3. Tracy, CA
Issue Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
OSTI Identifier:
873394
Patent Number(s):
6150630
Assignee:
Regents of University of California (Oakland, CA)
Patent Classifications (CPCs):
F - MECHANICAL ENGINEERING F42 - AMMUNITION F42B - EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
B - PERFORMING OPERATIONS B23 - MACHINE TOOLS B23K - SOLDERING OR UNSOLDERING
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
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; /219/

Citation Formats

Perry, Michael D, Stuart, Brent C, Banks, Paul S, Myers, Booth R, and Sefcik, Joseph A. Laser machining of explosives. United States: N. p., 2000. Web.
Perry, Michael D, Stuart, Brent C, Banks, Paul S, Myers, Booth R, & Sefcik, Joseph A. Laser machining of explosives. United States.
Perry, Michael D, Stuart, Brent C, Banks, Paul S, Myers, Booth R, and Sefcik, Joseph A. Sat . "Laser machining of explosives". United States. https://www.osti.gov/servlets/purl/873394.
@article{osti_873394,
title = {Laser machining of explosives},
author = {Perry, Michael D and Stuart, Brent C and Banks, Paul S and Myers, Booth R and Sefcik, Joseph A},
abstractNote = {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.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2000},
month = {1}
}