Laser machining of explosives
First Claim
1. A method for machining explosive materials, comprising:
- producing a pulsed laser output beam comprising a plurality of laser pulses wherein each pulse of said plurality of laser pulses has a pulse repetition rate greater than 1 Hz, wherein each said pulse has a pulse duration of 50 picosecond or less; and
directing said pulsed laser output beam onto a workpiece comprising explosive material, wherein each said pulse converts approximately 0.01 to 1 micron of said explosive material of said workpiece from the solid state to the plasma state with substantially no transfer of thermal or mechanical energy into the remaining material and substantially no collateral damage thereto, wherein said explosive material is removed from said workpiece by hydrodynamic expansion of said plasma, wherein said plasma consists of inert gases and no toxic vapor, wherein said method does not induce detonation or deflagration of said explosive material.
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Accused Products
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.
199 Citations
9 Claims
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1. A method for machining explosive materials, comprising:
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producing a pulsed laser output beam comprising a plurality of laser pulses wherein each pulse of said plurality of laser pulses has a pulse repetition rate greater than 1 Hz, wherein each said pulse has a pulse duration of 50 picosecond or less; and directing said pulsed laser output beam onto a workpiece comprising explosive material, wherein each said pulse converts approximately 0.01 to 1 micron of said explosive material of said workpiece from the solid state to the plasma state with substantially no transfer of thermal or mechanical energy into the remaining material and substantially no collateral damage thereto, wherein said explosive material is removed from said workpiece by hydrodynamic expansion of said plasma, wherein said plasma consists of inert gases and no toxic vapor, wherein said method does not induce detonation or deflagration of said explosive material.
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2. A method for machining explosive material, comprising:
directing a laser beam onto a workpiece comprising explosive material, wherein said laser beam comprises a plurality of laser pulses, wherein each pulse of said plurality of laser pulses has a pulse repetition rate greater than 1 Hz, wherein each said pulse has a pulse duration within the range of 5 femtoseconds to 100 picoseconds and a focused irradiance of greater than 1012 W/cm2, wherein each pulse of said plurality of laser pulses converts approximately 0.01 to 1 micron of said explosive material of said workpiece from the solid state to the plasma state with substantially no transfer of thermal or mechanical energy into the remaining material and substantially no collateral damage thereto, wherein said material is removed from said workpiece by hydrodynamic expansion of said plasma, wherein said plasma consists of inert gases and no toxic vapor, wherein said laser beam produces no detonation or deflagration of said explosive material. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9)
Specification