Abstract:
The valve is designed for the ejection of a plurality of different gases from within the valve, simultaneously, by having a plurality of plenum chambers within the chamber of the valve, and a poppet therein, that are charged with gases under pressure. The gases are sealed within the respective plenum chambers by the action of a spring that urges the poppet against a gas exit port associated with each plenum chamber. Ejection of the gases is accomplished by the application of an electrical current into a coil surrounding the poppet which produces an electromagnetic field that causes a non-ferrous hammer to be driven away from the coil and strike the poppet. Upon being struck by the hammer, the poppet is driven off of the plurality of gas exit ports thereby allowing the gases to be ejected, simultaneously, from the respective plenum chambers into a region of lower pressure.

Description:
This is a divisional application of application Ser. No. 08/709,954, filed Sep. 9, 1996 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention pertains generally to a valve and more particularly to a fast valve capable of ejecting a plurality of gases, simultaneously. 
     2. Description of the Related Art 
     In operations, such as the production of a dense plasma, gas is injected into a chamber. In this type of operation, as well as many others, there is a need for a valve to deliver a puff of gas within a short period. A delay between the valve opening the operation may cause the operation to be unsuccessful. 
     Currently, a typical valve for use in plasma production operates through the use of diamagnetic repulsion, has only one gas chamber and, therefore, operates with only one gas or gas mixture at a time. This type of valve  10  is shown in FIG. 1 and operates by discharging a capacitor (not shown) into a coil  12  thereby creating a magnetic field that repels an aluminum ring  14  which rests above the coil  12 . The ring  14  is allowed to accelerate through a predetermined distance, thereby achieving a large velocity before striking a nylon poppet  16 . The poppet  16  is then driven off an O-ring  17 , opening the valve  10  and permitting a gas to flow through the gas inlet  18  and out the gas outlet  19 . Use of this two stage process of valve opening reduces the rise time when compared with designs using magnetic forces to open the valve directly.  Compare, Simple, fast, puff valve , Rev. Sci. Instrum. 62 (10), pp. 2372-2374, October 1991; U.S. Pat. No. 4,771,447, Saitoh et al., 1988; Kriesel et al., and Wong et al.,  Balanced puff valve for imploding gas - puff experiments , Rev. Sci. Instrum, 57(8), pp. 1684-1686, August 1986. Some experiments require the use of two gases, therefore, two, separate, independently working fast valves are required to provide concentric gas streams. See, Finken et al.,  The Gas - Liner Pinch—A New Spectroscopic Light Source , Phy. Ltrs. Vol. 85A, No. 5, pp. 278-280, October 1981. However, the use of two valves creates problems with gas rise times which is dependent upon the length that a gas has to travel downstream of the valve. In a two-valve system, one valve has to be displaced farther back or to the side of the other and this requires long flow tubes which in turn causes the gas rise time to be longer. A longer gas rise time allows the gas to diffuse with the other gas or into the chamber and cause electrical breakdown. 
     SUMMARY OF THE INVENTION 
     The object of this invention is to provide a valve capable of ejecting a plurality of gases, simultaneously, into an a chamber. 
     This and other objectives are accomplished by the use of a valve having a plurality of plenum chambers for the storage of several gases under pressure. A poppet within the valve is displaced by an electromagnetic force thereby allowing the plurality of gases to be ejected, simultaneously, from the plenum chambers into a region of lower pressure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows the prior art of a valve for use with a single gas. 
     FIG. 2 a  shows a valve capable of ejecting a plurality of gases. 
     FIG. 2 b  shows a bottom view of the valve shown in FIG. 2 a.    
     FIG. 3 shows an alternative base plate having annularly configured supersonic nozzles for both the first and second plenum chambers. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     For the purpose of simplification, the valve described below is one that is used for the injection of two gases into a region of lower pressure, this type of valve is commonly referred to as a puff valve. However, the invention may be used for other applications and additional gases may be accommodated without detracting from the scope or spirit of the invention as described in the claims. 
     The valve  20 , as shown in FIG. 2 a , is comprised of a valve housing  24 ; a poppet  22 , contained within the valve housing  24 ; a metallic valve base  32 , and a metallic nozzle section  34 . The valve housing  24  is further comprised of two sections having cavities within—an upper housing  26  made of a metal such as stainless steel or aluminum, and a poppet section  28  made of a non-metallic material such as fiberglass epoxy. The poppet section  28  is further divided into an upper and lower portion  28   a  and  28   b , respectively, having a tubular cylindrical shape. Within the upper and lower portions  28   a  and  28   b  of the poppet section  28  is located the poppet  22 . To the lower portion  28   b  of the poppet section  28  is attached a metallic base plate  32  containing inlets and outlets for directing the flow of gases. A metallic nozzle section  34  attached to the metallic base plate  32  to complete the valve  20  structure. The nozzle section  34  contains a plurality of supersonic nozzles  64  configured in an annular pattern, as shown in FIG. 2 b , and a single nozzle  66 , to direct and accelerate the discharge of the gases into a test chamber, such as a vacuum chamber (not shown), is (Although the valve base  32  and nozzle section  34  are metal in the preferred embodiment, they may be made of any suitable material, metallic or non-metallic.) The cavity within the upper housing  26  and poppet housing  28  forms a first plenum chamber  56  for the storage of a first gas. 
     The upper portion  28   a  of the poppet section  28  is tubular, without any protrusions. The lower portion  28   b  of the poppet section  28  is also tubular but has a circular protrusion, or shoulder,  28   c  located within the cavity. Positioned on the upper portion of the shoulder  28   c  is a ring-type magnetic coil  42 . The magnetic coil  42  is a ribbon wound coil having fiberglass material between the windings, a type well known to those skilled in the art. The poppet  22  is disposed inside of the circular shoulder  28   c  and extends from the lower portion  28   b  into the upper portion  28   a  of the poppet section  28 . 
     The poppet  22  is machined from a solid block of nylon, or a similar non-conducting material, has a skirt  22   a  extending outward from its lower portion extending into the first plenum chamber  56 , this skirt  22   a  provides a gas seal and acts to control for the discharge of the gas within the first plenum chamber  56 . The material on the lower portion of the interior of the poppet  22  is removed so as to form a second plenum chamber  46  for the storage of a second gas. Within the second plenum chamber  56 , a plunger  22   c  extends through the center to a point parallel to the to the face of the shirt  22   a . The plunger  22   c  provides the gas seal and acts to control the discharge of the gas from the second plenum chamber  46 . Flow of gases between the first and second plenum chambers  56  and  46 , respectfully, is prevented by the use of O-rings  27  between the poppet  22  and a circular ring  29  extending up into the second plenum chamber  46  from base plate  34 . By utilizing the poppet  22  to control the discharge of the gases from both the first and second plenum chambers  56  and  46 , respectively, simultaneous discharge of the gases is achieved. (The selection of fiberglass, or any other suitable non-conducting material for the poppet section  28  and poppet  22  is essential so as not to induce an interference with the operation of the magnetic coil  42 .) 
     The part of the poppet  22 , extending into within the upper portion  28   a  of the poppet section  28  has a circular nylon shoulder, or striking pad,  23  attached to the top of the poppet  22  by machine screws  48 , preferably aluminum. (However, any type screw made of a similar light and strong material may be utilized.) This striking pad  23  provides a striking surface for a circular ring, or hammer,  38 , which is disposed atop the magnetic coil  42  in the inactivated or rest position. The hammer  38  is of approximately the same size and shape as the magnetic coil  42  and is made of a non-ferrous metal such as aluminum. 
     In the rest position, the hammer  38  is urged against the magnetic coil  42  by the hammer return spring  44 . The hammer return spring is of a type well known to those practicing the art and must only be of sufficient strength to return the poppet to the rest position after activation, in this embodiment a one ounce spring was found to be adequate. It is noted that if the hammer  38  were made of a ferrite metal would nullify the effectiveness of the magnetic coil  42 , so it is essential that the hammer  38  be made of a non-ferrous metal. 
     The poppet  22 , in the rest position, is urged against the metallic valve base  32  by a poppet return spring  52  extending out of the upper valve section  26  onto the collar  23  of the poppet  22 . This urges the shoulder  22   a  of the poppet  22  against an O-ring  58  around a gas exhaust port  66   a  for the gas contained within the first plenum chamber  56  thereby preventing the gas resident within the first plenum chamber  56  from escaping. Also, the plunger  22   c  is urged against an O-ring  74  around the gas exhaust port  64   a  in the valve base  32  sealing off the exit port  64   a  for a gas contained within the second plenum chamber  46 . 
     Prior to conducting any experiment, the first and second plenum chambers  56  and  46 , respectively, are filled with a gas or plurality of gases, such as argon or hydrogen. In this embodiment, the first gas provided the first plenum chamber  56  is applied through a gas port  72  located at the top of the upper valve housing  26  and the second gas is provided to the second plenum chamber through gas inlet  68  through a passage  59 . In designs having more than two plenum chambers each plenum chamber would have its respective gas inlet and outlet. 
     Activation of the valve  20  accomplished by application of an electrical current to the magnetic coil  42 . Upon application of the electrical current, the resulting electromagnetic field from the magnetic coil  42  causes eddy currents to form in the hammer  38 , thereby creating a repulsive force causing the hammer  38  to be driven away from the magnetic coil  42  and strike the nylon shoulder  23  of the poppet  22 . When struck, the poppet  22  is driven away from its rest position, the poppet return spring  52  is compressed, and the poppet shoulder  23  is urged against an O-ring  54  in the upper valve housing  26  sealing off the first plenum chamber  56 . The gases in the first and second plenum chambers  56  and  46 , respectively, are allowed to flow through the exit nozzles  66  and  64 , respectively, into the test chamber (not shown). 
     The poppet spring  52  is of a type well known to those practicing in the art and must only have sufficient force to return the poppet  22  to the its original position after activation, in this embodiment an eight ounce spring was found to be adequate. The O-rings described above are preferably butyl rubber, but any acceptable material may be utilized as long as it is compatible with the test gases and valve materials. 
     A sensor  57 , biased at a predetermined voltage (in this instance 1000 volts), is located on the base plate  34  to indicate that gas has begun to flow from the plenum chambers, through port  57   a . When the gas has been dispelled from the plenum chambers  56  and  46 , the poppet  22  is returned to the rest position by the poppet spring  52 , the valve  20  is ready to be recharged with the gases for another experiment. The recharging sequence and triggering of subsequent experiments may be controlled through the use of the sensor  57  and separate electronic control circuits (not shown). 
     In a second preferred embodiment, as shown in FIG. 3, a nozzle plate  68  comprised of a manifold section  68   a  and a nozzle section  68   b  is attached to the base plate  32 . This configuration differs from that previously described in that the exhaust nozzles  72  from the second plenum chamber  46  are annularly configured supersonic nozzles as are the annularly configured exhaust nozzles  67  for evacuating the gas from the first plenum chamber  56 . This allows for a wider dispersion of the second gas into the vacuum chamber (not shown). 
     In both embodiments the design of the nozzle plates  34  and  68 , the essential criteria for the exit nozzles  66  and  72  is symmetry. The number of nozzle openings is left to the discretion of the designer, the only requirement being that they are uniformly symmetrical. 
     Although the invention has been described in terms of the exemplary preferred embodiments thereof, it will be understood by those skilled in the art that still other variations and modifications can be affected in this preferred embodiment without detracting from the scope or spirit of the invention. Such as, the valve  20  is shown in the upright position, in actual operation the position of the valve is immaterial. Also the designer may develop configurations having more plenum chambers than the two illustrated in the preferred embodiment. Also, forming the poppet  22  in two sections in this embodiment is merely to facilitate the assembly of the valve  20 , if the valve  20  can be designed so as to not require a two-piece poppet section  28  for assembly, a one-piece design may be substituted.