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MagnetoHydroDynamic (MHD) Means for Creating Fine, Liquid Metal Jets

IP.com Disclosure Number: IPCOM000173526D
Publication Date: 2008-Aug-11
Document File: 2 page(s) / 45K

Publishing Venue

The IP.com Prior Art Database

Abstract

Small diameter, precise, Liquid Metal (LM) jets have many applications but are difficult to create. For example, a 200 μm diameter jet of Fe moving at 30 m/s requires a plenum driving pressure of 3.5 MPa = 507 psig. Fe melts at 1535ºC; the combination of high pressure and high temperature, plus the need for uninterrupted liquid metal flow makes construction of a robust industrial system difficult.

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PUBLIC CONCEPT DISCLOSURE

Title: MagnetoHydroDynamic (MHD) Means for Creating Fine, Liquid

Metal Jets

    Small diameter, precise, Liquid Metal (LM) jets have many applications but are difficult to create. For example, a 200 µm diameter jet of Fe moving at 30 m/s requires a plenum driving pressure of 3.5 MPa = 507 psig. Fe melts at 1535ºC; the combination of high pressure and high temperature, plus the need for uninterrupted liquid metal flow makes construction of a robust industrial system difficult.

    A new way of creating LM jets has been conceived of, this approach employs the following concept: Lorentz force = j x B, where: j is current density and B is magnetic field strength. In use, a small voltage is applied between + and - electrodes in contact with the LM forcing a current j through the LM. Perpendicular to the current and the axis of the emerging jet, is arranged- a strong magnetic field B, created either by electro- or permanent magnets. According to the Lorentz Law (F = j x B), this arrangement of current vector j and magnetic field vector B creates a body force F, which may be directed along the jet axis. The body force, without any pressure drop across the nozzle, can cause a fine LM jet to issue from the nozzle. The jet's temperature will be at least the melting temperature of the metal. The jet's temperature may be raised further by I2R

heating of the LM in the MHD accelerator or, especially preferred, by I2R heating of the jet between its nozzle and the workpiece. By these means the LM temperature can be raised nearly to the LM boiling point (2750°C for Fe).

    This concept of a MHD accelerator not relying upon any substantial pressure in a LM plenum upstream of the jet nozzle will make the accelerator's construction much easier because pressure stresses on the materials of construction are eliminated. Further, LM can be fed into the top of the MHD accelerator without need for a pressure lock. While this article/concept focuses...