The Task

Valving superfluid helium is a difficult task in cryogenic apparatus design.  As helium is chilled below the liquid state, helium becomes "superfluid" or a quantum fluid which acquires some unusual properties and obeys the laws of quantum mechanics more than classic mechanics.  The challenge for a valve designer is that the fluid functionally has no viscosity.  Therefore the closure must be precise and very high seat to poppet pressures are required for the valve.  These pressures approach the elastic limit of the seat material or poppet material.  In order to activate a well sealed mechanical valve a forceful long throw prime mover that generates only microwatts of waste heat is required.  TbDy actuators are ideal for this task.

The Invention

In order to achieve the force required to lift the poppet from the valve seat, a TbDy magnetostrictive crystal is activated by a 1000 gauss field.  This field is generated from a small high temperature superconducting (HTSC) coil.  Because the coil is superconducting no significant waste heat is generated (at the microwatt level).  A variation of the device uses a superconducting flux tube to maintain an open or closed state indefinitely, without power applied.


• high temperature super conducting HTSC solenoid activation up to 77 Kelvin for testing
• a small dead volume on experiment side of 20 microliters
• negligible heat of operation
• high sphericity ball used to generated seat
• flux tube option for steady state, current-off operation.

The Inventors and Developers

Valve Design: Robert Chave
Valve Development: Christian Lindensmith, JPL
HTSC Coil Development John Voccio, America Superconductor

NASA Awards

NASA New Technology Award, NPO-20271: "Liquid Helium Valve for Use at Cryogenic Temperatures with Magnetostrictive Actuation"

NASA New Technology Award, NPO-20502/0100b: "Superconducting Flux Tube (SFT) Actuation of magnetostrictive Valve for Cryogenic Application" 

Patent Claims

United States Patent entitled " Magnetostrictive Actuation", Serial Number 09/183,387, R. Chave, C. Lindensmith, J. Dooley, B. Fultz, and M. Birsan, Application filed, Oct. 29, 1998 claiming the benefit of U.S. Provisional Application No. 60/063, 991, filed Oct.  29, 1997

picture NASA Tech Briefs & RGC

first test in liquid nitrogen of valve
picture C Lindensmith


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