US3826452A - Electrical control device for a re-entry vehicle - Google Patents

Abstract

An Electron-Deflection Device comprising an electron gun, a Chladni deflector. The Chladni deflector is comprised of a double helix ring electrode assembly. The nose of the re-entry body is encircled by a series or plurality of ring electrodes which are alternately positively and negatively charged. Upon re-entry the plasma generated by the leading edge of the nose would be deflected away from the skin of the re-entry body. This concept would allow communication with the vehicle by external RF signals.

Description

United States Patent [191 Little [111 3,826,452 [4 July 30, 1974 ELECTRICAL CONTROL DEVICE FOR A RE-ENTRY VEHICLE Inventor: William A. Little, Palo Alto, Calif.

The United States Of America as represented by the Secretary of the Navy, Washington, DC.

Filed: May 25, 1973 Appl. No.: 363,905

Assignee:

US. Cl 244/1 SS, 244/1 A, 317/2 E Int. Cl. B64g 1/00 Field of Search..... 244/1 SS, 1 SA, 1 SB, 1 SC,

References Cited UNlTED STATES PATENTS King 244/1 SB X Null 244/1 SA X Cason 244/1 SA X 4/1970 Engclbcrger 244/1 SB PLASMA FLOW FOREIGN PATENTS OR APPLICATIONS 1,406,417 1/1969 Germany, 244/1 SS Primary Examiner-Trygve M. Blix Assistant Examiner-Barry L. Kelmachter Attorney, Agent, or Firm-R. S. Sciascia; Charles D. B. Curry [5 7] ABSTRACT An Electron-Deflection Device comprising an electron gun, a Chladni deflector. The Chladni deflector is comprised of a double helix ring electrode assembly.

- The nose of the re-entry body is encircled by a series or plurality of ring electrodes which are alternately positively and negatively charged. Upon re-entry the plasma generated by the leading edge of the nose would be deflected away from the skin of the re-entry body. This concept would allow communication with the vehicle by external RF signals.

4 Claims, 4 Drawing Figures PAIENIEDJHLBOIQH I j 3.826.452

I3 ll l7 SCREEN -400 -soo -2oo -|oo '0 I00 200 300 400- ELECTRODE PEAK TOPEAK VOLTAGE PLASMA FLOW F|G 3. v e FIG-4 BACKGROUND OF THE INVENTION 1. Field of the Invention The subject matter of the present invention relates generally to the use of modified Chladni deflection device for use with a re-entry body and more particularly encircling a re-entry body with a series of double ring helix electrodes which are alternately positively and negatively charged to repel the charged plasma and allowing communication with the re-entry body by external RF signals. Moreover by varying the potential of the electrodes a certain amount of control of the attitude of the re-entry body may be achieved.

2. Description of the Prior Art In the past, the charged plasma surrounding a reentry vehicle has made it impossible to communicate with the re-entry vehicle during the re-entry phase of flight.

SUMMARY OF THE INVENTION The present invention relates to an Electrondeflection device comprising an electron gun, a Chladni deflector and a flexible support member. The Chladni deflector is comprised of a double helix electrode assembly. The nose of the re-entry body is encircled by a series or plurality of the ring electrodes which are alternately positively and negatively charged. Upon re-entry the plasma generated around the leading edge of the nose would be deflected away from the skin of the re-entry body. This concept would allow communication with the vehicle by external RF signals. Because both positively and negatively charged particles are acted upon by Chladni forces generated from the Chladni deflector device a charged plasma can be deflected or repelled with these forces. The same concept may be used to confine or accelerate charged particles by means of a spatially varying electric field. Virtually no power is required because the field is electrostatic in nature.

STATEMENT OF THE OBJECTS OF THE INVENTION A primary object of the present invention is to provide a device which will deflect, confine or accelerate charged particles in an electric field. Another object of the present invention is to provide a device which will accelerate charged particles by means of a spatially varying electric field.

Another object of the present invention is to provide a device which will deflect or repel a charged plasma generated by the leading edge of the nose of a re-entry body.

Another object of the present invention is to provide a device which will allow communication with a reentry body, during the re-entry phase, by external RF signals.

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of the deflecting device assembly.

FIG. 2 is a graphical representation of the observed deflection of the electron beam as a function of electrode potential V,,.

FIG. 3 is a pictorial representation of a re-entry body using a series of equivalent deflecting devices illustrated in FIG. 1.

FIG. 4 is a cross sectional area of the re-entry body of FIG. 3, the appropriately charged deflecting apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As background for the subject invention it has been found that a particle moving in a time-dependent spatially inhomogeneous field is acted upon by a timeaveraged force which acts along the negative of the gradient of the oscillatory kinetic energy. This action or force was demonstrated by E. F. F. Chladni, in Theory des Klanges (Weidmans, Leipzig, 1787). For example, when fine powder or sand is placed on a vibrating surface the sand moves away from the regions which are vibrating most vigorously and eventually settles along the nodal lines. This has become known as Chladni figures.

A complete description of the theoretical background for the subject invention can be found in the J. Appl. Phys., Vol. 43, No. 6, June 1972. However, it should be noted that the subject invention was not disclosed in the Journal.

Referring to FIG. 1, the device 11 is generally comprised of an electron gun 13 and a double electrode assembly 17. The electron gun 13 is a standard type which has been modified to function in conjunction with the helix assembly 17. The device of FIG. 1 is used to show the basic principle of Chladni deflection. Referring to FIG. 1, helix electrode assembly 17 is placed in evacuated enclosure 21 so that a beam x of charged particles may be confined to move along the axis of the cylindrical cross section of enclosure 21 by maintaining a spatially varying electric field along the wall of enclosure 21. The beam x is deflected away from this inhomogeneous electric field region and is trapped within enclosure 21. Provided that the angle of incidence of beam x is prevented from exceeding the critical angle, the total internal reflection of the electric beam x would occur at the inhomogeneous field region near the walls of the enclosure and the entire beam x would eventually appear at the far-end of the enclosure 21 regardless of any bends in the enclosure 21 itself. Referring to FIG. 1, the double electrode assembly 17 is comprised of a first line of electrodes 17a and a second line of electrodes 17b all of the same diameter. The pitch of each of the double electrodes 17 is preferably the same. Using this general configuration, at similar beam energies and potentials, the beam could be confined along the electrodesaxis and transported without loss from end to end even if the axis of the electrodes are deformed. The basic principle of Chladni deflection can be demonstrated with the apparatus shown in FIG. 1. In operation, a particle e is emitted from cathode 19 or an equivalent device, and is accelerated through a potential V over an array of positive and negative charged electrodes 17. The moving charge is subject to an oscillatory electric field whose magnitude will be greater the closer the trajectory approaches the array of electrodes. It has been found that this field will give rise to an oscillatory motion perpendicular to the direction of the initial velocity. This results in a timeaveraged force which deflects the particle away from the force as illustrated by beam x in FIG. 1, wherein b is the beam injection height and a .is the individual electrode spacing above the plane of the electrodes. The beam 1: will be deflected through an angle 0, where O (V /2 2V. The results are graphically illustrated in FIG. 2 where the linear dependence of the deflection is dependent upon V and illustrates that the deflection is clearly independent of the sign of V Thus, when an electron beam is accelerated through a potential V and is injected along the axis of double electrode assembly 17, with one electrode changed to a potential V+V and the other electrode changed to a potential V-V this produces the desired inhomogeneous field region near the walls of member 15, see FIG. 1. For a beam energy of about 780V, confinement occurs at about V,, 500V. I

Using the concepts of the device illustrated in FIG. 1, a re-entry body may be protected during there-entry phase preventing the promotion of a large plasma cloud around the body so that it would be possible to communicate with the vehicle by external RF signals. Referring to FIGS. 3 and 4, re-entry body 31 is encircled by a double ring helix 33 electrodes which are alternately positively and negatively charged. The double ring helix is compris'edof a first ring helix array 33a and a second ring helix array 33b. Array 33b is connected to a standard power source, not shown, so that it has a charge opposite that of array 33a. Arrays 33a and 33b are each spirally wound around the entry skin 35 of the re-entry body 31 and converging toward the tip of nose 34. Referring to FIG. 4, the outer skin 35 is constructed of an ablative material is attached to inner hull 32 of re-entry body 31. The outer skin 35 of ablative material provides the necessary insulation between oppositely charged arrays 33a and 33b. The arrays 33a and 33b are preferably recessed so that they are flush with the outer skin. The ablative material or skin 35 may be made of any material well known in the art. The arrays 33a and 33b may be attached to 32 by any number of well known methods; however, an insulation adhesive may be used to attach the arrays 33a and 33b to hull 32. The arrays 33a and 33b may be constructed of any suitable construction material presently available. By using this principle of deflecting the plasma formed by ionizations at the tip of nose 34 of re-entry body 31 none of the hot plasma would strike the skin 35 of the reentry body 31 and hence the re-entry body 31 would be re-used many times. This concept also prevents the conducting material forming the arrays 33 from melting. As the atmosphere becomes more dense and the m.f.p. of the gas atoms are shortened the potential between the arrays 33a and 33b would be reduced, but it has been found that the lower velocity of the body 31 would make it easier to deflect the plasma beam. The attitude of the body could also be controlled by varying the potential between arrays 33a and 33b. This could be achieved by use of any well known power control systems presently available, either AC or DC. The reentry body 31 may be of any type well known in the art. Since both the positive and negative charged particles are acted upon by the Chladni forces, the charged plasma can be deflected with these forces such that the plasma generated by the leading edge of the nose 34 of the body 31 would be deflected away from the skin of the body 31. This results in less energy being dissipated in the ablative shield. The same concept may be used to confine or accelerate charged particles by means of a spatially varying electric field. Virtually no power is required because the field is electrostatic.

A plurality of the ring electrodes which form the ring helix 17 illustrated in FIG. 1 wherein each array 33a and 33b spirally encircle the outer skin of the body 31. The arrays 33a and 33b may be connected to any standard power source in any well known manner. Thw power source is not illustrated.

The helix array 33a and the helix array 33b are positioned around hull 32 and spiral around hull 32 and converge towards the tip of nose 34 of re-entry body 31. It should be noted that the helix arrays 33a and 33b may be made to converge at the tip of nose 34 if desired. Referring again to FIG. 4, charged helix array 33a is located and positioned between helix array 33b; helix array 33b is charged opposite to that of helix array 33a, this allows the plasma flow to be deflected away from re-entry body 31. It should be noted that arrays 33a and/or 33b can be charged positively or negatively, as the case may be, as long as one helix array is charged opposite to the other helix array.

What is claimed is: 1. An electron deflecting device for a re-entry body operating in a plasma environment comprising in combination:

a. a first helix shaped assembly spirally wound around the outer skin of the re-entry body;

b. a second helix located between said first heli shaped assembly and wound around the outer skin of the re-entry body, said first and second helix shaped assemblies uniformly spaced along the outer skin of said re-entry body; and

c. a means for electrically charging said first helix opposite that of said second helix.

2. The device recited in claim 1 wherein said first helix is located within the inside perimeter of said second helix.

3. The device recited in claim 2 wherein the pitch between said first helix and said second helix is uniform along the entire area of the outer skin of said re-entry body.

4. The device recited in claim 3 wherein the electrical potential between said first helix and said second helix is varied with respect to each other.

Claims (4)

1. An electron deflecting device for a re-entry body operating in a plasma environment comprising in combination: a. a first helix shaped assembly spirally wound around the outer skin of the re-entry body; b. a second helix located between said first helix shaped assembly and wound around the outer skin of the re-entry body, said first and second helix shaped assemblies uniformly spaced along the outer skin of said re-entry body; and c. a means for electrically charging said first helix opposite that of said second helix.

2. The device recited in claim 1 wherein said first helix is located within the inside perimeter of said second helix.

3. The device recited in claim 2 wherein the pitch between said first helix and said second helix is uniform along the entire area of the outer skin of said re-entry body.

4. The device recited in claim 3 wherein the electrical potential between said first helix and said second helix is varied with respect to each other.

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