US3914766A

US3914766A - Pulsating plasma device

Info

Publication number: US3914766A
Application number: US406801A
Authority: US
Inventors: Richard L Moore
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-09-24
Filing date: 1973-10-16
Publication date: 1975-10-21
Anticipated expiration: 1992-10-21

Abstract

A pulsating plasma device is disclosed having a cylindrical plasma column and a pair of field exciter members disposed in spaced parallel relationship to the plasma column. Means are also provided for creating an electrostatic field through which oscillating energy is transferred between the plasma column and the field exciter members.

Description

United States Patent 1 1 Moore Oct. 21, 1975 1 PULSATING PLASMA DEVICE [56] References Cited [76] Inventor: Richard L. Moore, 2409 East St., UNITED STATES PATENTS Davenport. Iowa 52803 2,435,609 2/1948 Schelkunoff 343/701 3,155,924 11/1964 Kaufman et a1 333/99 PL UX [22] 1973 3,238,531 3/1966 Kaufman et al. 343/701 [21] Appl, No.: 406,801

Primary ExaminerPaul L. Gensler l l t w U S App [ca [on Data Attorney, Agent, or FirmDavid A. Blumenthal [63] Continuation-impart of Ser. No. 75,045, Sept. 24, 1970, abandoned, which is a continuation-in-part of Ser. No. 840,087, June 2, 1969, abandoned, which is 1 ABSTRACT a continumlonm'part of 40814641 A pulsating plasma device is disclosed having a cylin- 964, abandoneddrical plasma column and a pair of field exciter members disposed in spaced parallel relationship to the [52] US. Cl. 343/701; 176/1; 176/8; plasma column Means are also provided for Eating 315/39 315/111: 333/99 PL an electrostatic field through which oscillating energy [51] Int. Cl H01q l/26, G21b 1/00 is transferred between the plasma column and the [58] Fleld of Search 328/16, 19; 331/126; field exciter members 10 Claims, 5 Drawing Figures US. Patent Oct. 21, 1975 Sheet1of2 3,914,766

Output Signal WM 6912a INVENTOR. 2/0/7042 L MOO/Q5 ATTORNEYS U.S. Patent Oct. 21, 1975 Sheet2 0f2 3,914,766

PULSATINC PLASMA DEVICE RELATED APPLICATIONS I The present applicationis a continuation-in-part of my prior application, Ser. No. 75,045 filed Sept. 24, 1970, now abandoned, which is a continuation-in-part of application, Ser. No". 840,087, filed-June 2, 1969, now abandoned, which'is a continuation-in-part of apabandoned. I e i I c su ARYoF THE INVENTION The present invention relates to utilization of the norrnal 'r'nod'es of vibration of-radial, angular, or axial motion of a non-uniform plasma or of a non-uniform electron gas in va-"plasina. The illustrated embodiment of the invention utilizes electron'gas in'a cylindrical plasma 2 the same time an important objective is to operate the devices so as to achieve high temperatures and pressures. lnmy invention I utilize the plasma waves to enhance the energy transfer, and to stabilize the motion at a desired frequency.

DRAWING SUMMARY FIG. 1 is a perspective view of a plasma antenna inc I v corporating my invention; plication, Ser. No: 40 8,464 filed Oct. 29, 196.4, now

column, in conjunction with a pair of field excite'r members which are coupledito" the plasma column throughagperiodic electrostatic field; so as to operate as a plasma antenna. Asecoiid devicei's. of the plasma type and utilized forcdntrolling nuclear fusion at resonant freduencies, operating with, a periodic magnetic field. Despitetheir differences the two devices are 'generally referred to as piilsating plasma device. I

Ini'the prior'art there has been considerable difficulty experienced in predicting the natural resonant frequency'ofan oscillating plasma column, and there has also been considerable difficulty experienced in determining" the proper design of field exciter members for achieving maximurri'powertransfer through the associated electric or magneticfield to.or""fromtlie plasma column itself, in thenu'rnber andlocation and configuration of the field excite'r members, and in the nature of the field through which'energy transfer is achieved, the underlying design problem has been that of analyzing the fundamental physical characteristics in order to be able to properly" predict their mode of operation. The mathematical theory set forth hereinis ofa general na ture and applies equally well whether the energy transfer is'through 'an electric field or through a magnetic field. Where either an electric 'or magnetic field is meant, the term force field is used. The theory is also equally applicable whether the number of field exciter members is one or more than one, and regardless of their location and configuration.

"Thus, the general object of the present invention is to provide a new and improved pulsating plasma device.

The more specific object of the invention is to provide animproved pulsating plasma device in whichthe num ber, location and configuration of one ormore field exciter members is so selected as to be in conformity to the existing characteristics of the plasma column, whereby maximum energy transfer' may be achieved between't'he fieldexci ter member(s) and the plasma col umn' Y,

"For severalyears it has been found by experimenters thatthe positive columnof a discharge tube has many more resonant frequencies than the one predicted by the'usual theory of such devices, namely, the'plasma or Langmuir-frequency. In my invention [utilize a more complete.understandingofthe phenomenon in order to achieve a more efficient device. it is'well-known that an important'current problem in the'control of thermonuclear reactions iri a plasma is, the stabilization of operationso "as t6 prevent unwanted oscillations and um wanted plasma waves from destroying confinement. At

' IG. 2 is a cross-sectional view of the device taken on the line '2-2' of FIG. 1;

"FIG. 3 is a cross-sectional view of the device taken on the line 3 3 of FIG. 2; and

FIGS. 4aand 4b are isometric and end views respectively'of the plasma fusion device.

PREFERRED EMBODIMENT In the'drawing a glass tube 2 having a cylindrical interior configuration contains a continuouspositive discharge column, and a sphere or bulb l is attached to one end of a tube 2 in communication therewith for supplying a continuous mercury arc discharge to the tube 2. The lower portion of sphere or bulb 1 contains two separate recesses which receive

respective electrodes

3a and 3b, each of these electrodes being surrounded by a'separate mercury pool 4, as shown in drawing FIG. 2. Electrode 3a is connected to the positive terminal of an external battery E typically of IS- volts potential, and terminal 3b is connected to the neg ative terminal of that battery which is also grounded. Electrodes Sa'and 3b are not necessarily of the same configuration, because one may protrude upward and be bent over the other so as to provide a relatively narrow gap. The mercury arc discharge occurs continuouslybetween the ends of the two electrodes, or between one electrode and the bath surrounding the other electrode. An electrode 5 is plugged into the other end of tube 2, and is also connected to the positive terminal of an external battery E whose negative terminal is grounded. The potential of battery E, is typically volts. Thus there is a constant potential difference between the two electrodes 30 and 3b of the bulb 1 and the electrode 5 is also maintained at a substantial positive potential relative to the bulb 1. This apparatus including the tube 2, sphere or bulb l,

electrodes

3a and 3b, mercury baths 4, electrode 5, and external batteries E and E is a conventional apparatus which is well-known and widely used for the purpose of establishing and maintaining a positive discharge columnof cylindrical configuration.

In order to stabilize the natural resonant frequency of the plasma column a blower 11 is utilized, having an outlet opening 12 which'is so positioned as to discharge cool air directly upon the full length of the tube 2. In this manner the plasma column is continuously cooled and its temperature maintained at a uniform level -'to the plasma column through the medium of a pair of 3 field exciter members 8. The members 8 have a substantial length, approximately equal to the length of tube 2, and are supported in spaced parallel relationship to the longitudinal axis of the plasma column. Insulating spacers 9 are utilized to support the two ends of members 8 in their proper spaced relationship, and at the same time a central hole or opening in each of the insulators 9 receives and supports the glass tube 2 so that the plasma column is mechanically supported in its proper position relative to the members 8. At one end the field exciter members 8 are physically attached to the upper and lower side walls, respectively, of the wave guide 7, in electrically conductive relationship thereto. As a result the vertically aligned exciting voltage E,. furnished from the wave guide 7 is also present between the members 8, as is shown in drawing FIG. 3.

According to the invention each of the exciter members 8 has a substantial surface width in a direction generally transverse to the longitudinal axis of the plasma column. Furthermore, the inner surface of each exciter member faces toward the plasma column and is curved in a plane that is perpendicular to the longitudinal axis of the column. The curved characteristic of the inner surface of each field exciter member 8 is also constant throughout a substantial length of the member. An additional characteristic which is extremely important, in accordance with the present invention, is that the curvature and physical positioning of the exciter members 8 are so selected that the near, or so-called force field developed thereby is at least approximately proportional to the sine ofm times the angle (in this case m is one). This relationship will be explained in a later section of this description.

In order to initiate the electron flow in tube 2 it is necessary to use a Tesla coil to break down the positive column, that being a conventional procedure.

When energy is supplied from wave guide 7 the device operates as an antenna, radiating energy outwardly from both sides of the plasma column as shown in FIG. 3. Specifically, the line P, shows the radiated or far field strength pattern, or lobe, on one side of the pair of members 8, and the curved line P shows the radiated or far field pattern on the other side. The generated signal strength is symmetrical on both sides of the device. Vertical arrows E, show the electric field polarization of the transmitted energy. The radiated field is proportional to cos m0. (In the case illustrated m is one).

While the device illustrated in the drawings has been described as a transmitting antenna, it also operates as a receiving antenna with equal efficiency. In that event the energy is received from some external source and picked up between the exciter members 8, being then transmitted into the wave guide 7.

While the present drawing illustrates a particular manner for initiating and maintaining a cold cathode discharge in the tube 2, it will be understood that these details are conventional and of no particular interest insofar as the present invention is concerned, and as a matter of fact the present invention is equally applicable to a hot cathode discharge or any other type of discharge that may be available for purposes of providing a confined cylindrical plasma column.

More specifically, it will be understood that the significance of the present invention is limited to the cylindrical configuration of the plasma column within the tube 2, the natural resonant frequency of that plasma column, the number and location and configuration of the members 8, and to the intended mode of operation 4 of the plasma column and the members 8 in conjunction with each other.

Some specific characteristics of the illustrated embodiment of the invention are as follows. The length of the positive column is 45 centimeters and its inside diameter is 5.6 mm. The length of field exciter members 8 is approximately 50 centimeters, their radium of curvature is 1.9 cm., and the distance between the inner surfaces of members 8 is approximately 2.5 cm. .Wave guide 7 is a standard C band wave guide. At a frequency of4 GHz with cooling air at F blowing over the tube, pure dipole resonances were found at currents of 375, 430, and 560 ma anode current. Coupling with axial modes was found at 700, 775, 830 and 925 ma. At a frequency of 5 GHz the dipoleresonances were found at 5 l5, 580,925 ma, and others which were. above the range of the measuring equipment. The resonant current for a given frequency is determined by, both the temperature of the positive column and the temperature of the mercury reservoir, both of which must be controlled to control the resonant current.T he power transmitted from the antenna at the main resonance for 4 GHz (560 ma) at a receiving horn on the plane of symmetry was approximately 6 db abovethe power transmitted with the discharge tube turned off.

A second embodiment of the invention is shown in FIG. 4 wherein a glass wall, 13, and a conductor 14 are shown in two views. Means are provided for introducing a gas into the glass cylinder and for pre-ionizing the gas to form the plasma in a conventional manner. The external electric circuits (not shown) are well-known in the art and are illustrated on page 9a of the publication by G. Decker, Report IPP l/5l, Institut fur Plasmaphysik, Garching Bei Munchen, Sept. I966. The plasma 15 is confined by the magnetic field formed by the current in conductor 14. The current in conductor 14 is caused to oscillate by an external circuit. The oscillation frequency is chosen as described below under the section entitled Modified Scylla Device.

MATHEMATICAL THEORY OF THE DEVICE The invention described herein consists of the combination of external electrical circuit, field exciter means, and a choice of plasma properties in order to more efficiently utilize the natural properties of the plasma.

A cylindrical plasma will not have a density which is uniform from the axis to the edge. Rather the density, in many cases of interest, follows more closely the mathematical curve known as a gaussian with a characteristic value (length) in the radial direction which is 0' (the standard deviation). The gaussian curve is described mathematically by the function:

where n, is the number of particles per cc,on the axis of the plasma, r is the distance in meters from the axis.

If the ions and electrons are warm, they each have a temperature T, and T respectively. In addition, because each of the gases is compressible, there is a sound speed corresponding to each gas an acoustic wave phase velocity in the plasma: the ion acoustic wave phase velocity, C.-, and the same for the electrons, C

However, the wave speeds are not simple expressions as in the usual expression for sound waves, but, involve, (l the angular frequency m (which is 21r times the oscillation frequency f), (2) the viscosity of the electron gas, w (3) the mass of the electron, m and the mass of an ion, m,, and (4) the ratio of specific heats, y, and y...

The expressions for C, and C, also include Boltzmans constant k, as follows:

Having a characteristic length and a characteristic sound speed C, then it is easy to show on dimensional grounds that the ratio C/o' would give a frequency of oscillation which would be appropriate for the fundamental frequency of radial pulsations.

In a more detailed analysis, I have shown that this frequency would actually be C/(VZmrl. If ion oscillations are desired than one uses the frequency C,-/(\/2mr); if electron oscillations are desired then one uses the frequency C /(V 271-0").

ln addition to the above frequencies there are many other resonances predicted and observed. These frequencies may depend on the spatial variation of the ex- 2 citing field which is induced in the plasma by the coupling means.

For example the above frequency formula applies where the coupling means is a single exciter former from a cylindrical annulus, which is split along the longitudinal axis at one point. Such a device is shown in FIGS. 4a and 4b and also on page 71 of Project Sherwood, by Amasa S. Bishop, Addison-Wesley Publishing Company, lnc., Reading, Massachusetts, USA. 1958. On each side of the split the leads to the external electrical circuit are connected. In this case thereis no variation either will angle or with the axis of the magnetic field generated by'current flowing around the annulus, at least in the center of the annulus.

As a second'example, if two properly designed parallel field exciter members are mounted parallel to the axis of a plasma column and on either side of it, and a potential difference applied between the field exciter members, then the azimuthal electric far field near the column will have an angular variation proportional to the cosine of the angle from the midplane which angle is denoted as Theta (0). (See HO. 3). lfa larger and arbitrary number of exciters are used, the far field, which is perpendicular to the plane from the point to the axis, will be made proportional to cosine of in times 0, the angle, where m is an integer. The near field, which is along the radius from its point to the axis, would then be proportional to sin m0.

Similarly, if one so desired, he could cut the two parallel field exciter members into a series of short field exciter members each insulated from its neighbors. By properly arranging the phase of the input to each field exciter member segment, the exciting field will have a variation in the axial direction proportional to cos(1rpz/2L), where p is an integer, z is the distance along the column from the origin and L is the total length of the field exciter members.

If in the following I specify that m is three and p is two, for example, the man skilled in the art will know immediately how to arrange the field exciter members and their connections in order to accomplish the desired variation for the exciting field.

In addition to the design of the field exciter means, the external electric circuit should be designed or adjustable to operate at the resonant frequency of the plasma oscillations. Since either magnetic or electric coupling between two weakly coupled circuits will give maximum power transfer at resonance, provided both 6 circuits resonate or operate at the same frequency, the frequency of operation is obviously a critical design parameter.

The frequency of operation depends on m and p, as well as the plasma characteristics given previously. Thus, the man skilled in the art will need only to consult Table l for the resonant frequencies as a function of m and p in order to define the frequency which is to be used for a particular configuration of field exciter members.

The resonant frequencies, in general, are found through the solution of an eigenvalue equation, or resonance condition. As usual in such cases, there is a differential equation which defines the radial variation of the function which describes the radial motion. The solution of the differential equation for this problem is in general approximately proportional to F (A, B, D), (which is the well-known confluent hypergeometric function). The values of B and D in this function are determined both by the values of the coefficients of the differential equation and by the radial distance, r,,, from the axis to the surface of the plasma. Then the value of A, (called the eigenvalue) is determined by solving the equation which arises when 1F1(A, B D) is set equal to zero. Since B and D are given, A is the solution of a transcendental equation and may have several values, i.e., A A A etc, and any one of these particular values is referred to generally as A,-. At the same time, we have derived from the differential equation, a theoretical expression, or equation, for A which may be set equal to the above set of values of A, and solved for the set of resonant frequencies. These frequencies will then be used by the designer. Table 1 shows the resonant frequencies in terms of eigenvalues A,- and the particular plasma parameters. The check (J) mark indicates motion and the cross (X) mark indicates no motion of the plasma in the R, 0, Z directions.

If in addition to the effects of previously mentioned variables, the electrons have a mean drift velocity; U, then the resonant frequencies may also be affected as will be shown by my formulas.

In addition it should be noted that if the plasma has a mean angular velocity about the axis denoted by the symbol 0, the formula for the standard deviation 0-, for a magnetically confined plasma is:

where H /M must be greater than 0 pJ-P/Z is the magnetic pressure at the surface of the plasma. pH /2, which stands for the magnetic pressure at the surface of the plasma, is a short-hand notation for the more general expression for the net inward stress on the plasma surface due to electric and magnetic fields. This general expression depends on the dielectric constant of free space, 6, and the electric field, E, and the component of E which is normal to the surface denoted as E The net inward stress is determined by evaluating the following expression just outside the plasma, and just inside the plasma surface currents and charges, and finding the difference, i.e., uH /2 stands for [(eE T n lluut [(GE2 u linwe sume, no component of pH is normal to, the surface. p is the permeablity of free space. M is the mass of the plasma per unit length. All units used are in the mks system.

The values of B and D are shown in Table l. The frequency of resonance is given as a function of the type of motion in the plasma and the spatial variation of the exciting field through the values of m and p. The value of A,- is to be computed from standard tables of the confluent hypergeometric function. It is of course noted that these results are based for the most part on approximate solutions of the differential equations which describe the motion.

lt should also be noted that for electron oscillations the value of C,. is to be used, and for ion oscillations the value of C,- is to be used. Table 1. Summary of approximate eigenvalue conditions: B 2; D /217 where r,, is the plasma radius.

onant frequency of this series combination is equal to the fundamental ion acoustic resonant frequency, or approximately 1.5 X 10 Hz. The starting circuit is then used only for starting, and the operating circuit is used only for operating. The additional circuit is then time sequenced with the Scylla starting coil by means of ignition switches which switch the circuit connections at that point of time when it is normal to crow bar the driving coil.

Having described the invention, what is claimed as new in support of Letters Patent is:

Motion type means:

R. motion component in radial direction;

0, motion component in azimuthal direction; Z. motion compound in axial direction MODIFIED SCYLLA DEVICE A schematic illustration of a conventional Scylla Device appears in the Project Sherwood reference previously cited. See also FIGS. 4a and 4b.

A typical Scylla Device is described in greater detail in an article by F.C. Jahoda, E.M. Little, W.e. Quinn, F.L. Ribe, and GA. Sawyer, in Journal of Applied Physics, Vol. 35, p. 2351, 1964. For the experiments described in that article the standard deviation of the radial density distribution is approximately 3.3 X l m. According to that article the circuit used for starting the device is also used for the subsequent operation. Alternatively, the portion of the circuit used for starting is short-circuited after the starting action has been accomplished.

With reference to the device described in the article, for the purpose of the present invention the ion sound speed may be inferred from the ion and electron temperature to be approximately 2.3 X 10 m/sec. Thus the fundamental ion acoustic resonant frequency from row 3, Table l with Q, m, and p equal to zero, would be approximately l.5 X Hz. The resonant frequency for electron vibrations would be approximately 92 X 10 Hz. According to the present invention the control of According to the present invention, the additional external circuit as illustrated in the Decker article menl. A pulsating plasma device comprising: means providing a cylindrical plasma column; at least one field exciter member having substantial length and being supported in spaced parallel relationship to the longitudinal axis of said plasma column and electrically insulated therefrom, said field exciter member having a substantial surface width in a direction generally transverse to the longitudinal axis of the plasma column, the inner surface of said field exciter member facing toward said plasma column being curved in a plane perpendicular to the longitudinal axis of said column; the curved characteristic of the inner surface of said at least one field exciter member being also constant throughout a substantial length of the field exciter member, the curvature and physical positioning thereof being so selected that the near force field developed thereby is at least approximately proportional to the sine of m times the angle 6; here In is an integer which is zero for one field exciter member and the near force field is magnetic, one for two field exciter members, and two for four field exciter members, and where 6 is the angle in cylindrical coordinates in the plane perpendicular to said longtudinal axis; and electric circuit means coupled to at least said one field exciter member and having an operating frequency related to the physical plasma characteristics in accordance with the following table:

Approximate Eigenvalues tioned above, consists of a capacitor and an inductor connected in series, with values so selected that the reswhere (R, 0 Z) are cylindrical coordinates of a coordinate system having its origin on the longitudinal axis of 3-,914; 7-6,6 said column and its Z axis along thelongitudinal axis of perature of the plasma throughout the length of said said-column and wherein,v i v W 7 column. R the motion component of the plasmain the radial 5. A. pulsating plasmadevice' as defined in claim 1 directiont. 1 wherein:

the motion component of the plasma in the azi- I there is only one of said ,field exciter members, the

muthal direction, inner surface of 'said field exciter member having a Z the motion component of the plasma in the axial substantially cylindrical configuration, and said opdirection, t i crating frequency defined by the following table:

Table Approximate Eigenvalue Conditions B=2; l)=r,,/2lr Motion Type Near Field Variation Frequency R 0 Z in p f v x x 0 o (cm/275x lie m? vv x o o cm/mildew x v 0 p Up/4L:[Cp /l6L lm l-A;)/21r fl p an integer, said oscillating energy transferred through a magnetic A, the eigenvalue of the confluent hypergeometric field.

function F (A, B, D) where 6. A pulsating plasma device as claimed in claim 5 B 2 wherein the value of A, is 0. D r,,"/' 25 7. A pulsating plasma device as claimed in claim 5 r the plasma radius wherein C is the ion acoustic wave phase velocity, and

0' the standard deviation of the plasma density in is defined by the equation the radial direction,

C the acoustic wave phase velocity in the plasma C2 (C02 ('YekT" zwvemefim" Q the mean angular velocity of the plasma col-. 3o 8. A pulsating plasma device as claimed in claim 5 umn about its axis, wherein C is the electron acoustic wave phase velocity, whereby said near field distribution at resonant freand is defined by the equation quencies has an azimuthal variation given by sin (m0) and an axial variation given by cos (1rpz/2L) C2 (C92 yekTelm" where, 9. A pulsating plasma device as recited in claim 5 L the total length along the longitudinal axis of the wherein said cylindrical field exciter is split along the field exciter members, longitudinal axis at one point and leads are attached to whereby the entire plasma device oscillates and the each side of said split cylinder for connection to said oscillating energy is transferred between said electric circuit means. plasma column and said field exciter member at v 10. In a pulsating plasma cylindrical column having said defined operating frequency. at least one field exciter member of substantial length 2. A pulsating plasma device as claimed in claim I positioned in spaced parallel relationship to the longiwherein: tudinal axis of said plasma column for providing radial there are two of said field exciter members, the inner ion oscillations in said column said field exciter memsurfaces of said field exciter members are convexly' ber electrically insulated from said column, said field curved, said electrical circuit means is a microwave exciter member connected to electrical circuit means circuit, and said oscillating energy is transferred for transmitting energy to and receiving energy from through an electrostatic field. said field exciter member, said electric circuit means 3. A pulsating plasma device as claimed in claim 2 operable at definite frequencies, a method of optimizwherein said microwave circuit means includes a wave-, ing the near field energy transferred between said field guide having a rectangular cross-section, and said two exciter member and said plasma column, comprising:

exciter members are physically attached to opposite selecting the operating frequency of said electrical side walls of said wave-guide in electrically conductive circuit means and the physical characteristics C, 0',

relationship thereto. r and Q of said plasma in accordance with the res- 4. A pulsating plasma device as claimed in claim 2 onant frequencies as determined by the table:

Approximate Eigenvalues which further includes means for cooling said plasma where (R, 0, Z) are cylindrical coordinates of a coordicolumn so as to maintain a substantially uniform temnate system having its origin on the longitudinal axis of said column and its 2 axis along the longitudinal axis of said column and wherein,

R =the motion component of the plasma in the radial direction,

the motion component of the plasma in the aximuthal direction,

Z the motion component of the plasma in the axial direction,

m is an integer which is zero for one field exciter member and the near field is magnetic, one for two field exciter members and two for four field exciter members,

p an integer,

A,= the eigenvalue of the confluent hypergeometric function F,(A,B,D) where B 2 D r,,

physical characteristics.

In the Claims UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,914,766

DATED October 21, 1975 INVENTOR( 1 Richard L. Moore It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In column 4, line 60, after "gas" insert a semicolon In column 5, line 3, delete .KT." and insert therefor l l .kT.--;

lines l4, l6 and 17, delete 27 and insert therefor --1/27fr-;

line 33, change "will" to -with-- InZcolumn 6, line 60, delete "p-H /2" and insert therefor In colunm 7, lines l6, l7 and 19, under the heading "Frequency" delete "VZM?" and insert therefor ---1 2"t/0-.

line 31, delete "W.e. Quinn" and insert therefor -W.E. Quinn--.

In claim 1, lines 37, 38 and 40, under the column labelled "Frequency", delete "4' 77" and insert therefor -7 27/fl'-'--.

In claim 5, lines 16 and 17, under the column labelled "Frequency", delete "427W" and insert therefor --1 2 71 In claim 10, lines 21 and 22, under the column labelled "Frequency", delete "427 and insert therefor /'2 ?ff-.

line 24, delete .Wvrr" and insert therefor "16W".

Signed and Scaled this SE I I sixteenth Day of March 1976 Arrest:

RUTH C. MASON Arresting Officer C. MARSHALL DANN (ummisxiuner ofParents and Trademarks UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. I 3,914,766

DATED October 21, 1975 |NVENTOR(S) Richard L. Moore It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In column 4, line 60, after "gas" insert a semicolon In column 5, line 3, delete .KT. and insert therefor ,.kT.--; 71 l l 1 lines l4, l6 and 17, delete "427W" and insert therefor 1 2'71r-;

line 33, change "will" to With- In2column 6, line 60, delete "p-H /2" and insert therefor In column 7, lines l6, l7 and 19, under the heading "Frequency" delete "1 27/0" and insert therefor --1 2 7f0'=--,

line 31, delete "W.e. Quinn" and insert therefor -W.E. Quinn--.

In the Claims In claim 1, lines 37, 38 and 40, under the column labelled "Frequency", delete "427W" and insert therefor -1 2 7/ In claim 5, lines 16 and 17, under the column labelled I "Frequency", delete "4 27/ and insert therefor -/?:7f1

In claim 10, lines 21 and 22, under the column labelled "Frequency", delete "427 and insert therefor 2 ?ff.

line 24, delete '4 770'" and insert therefor "15W".

Signed and Scaled this I sixteenth March A ttes t:

RUTH C. MASON Arresting Officer C. MARSHALL DANN ommixsiuner ofPatems and Trademarks

Claims

1. A pulsating plasma device comprising: means providing a cylindrical plasma column; at least one field exciter member having substantial length and being supported in spaced parallel relationship to the longitudinal axis of said plasma column and electrically insulated therefrom, said field exciter member having a substantial surface width in a direction generally transverse to the longitudinal axis of the plasma column, the inner surface of said field exciter member facing toward said plasma column being curved in a plane perpendicular to the longitudinal axis of said column; the curved characteristic of the inner surface of said at least one field exciter member being also constant througout a substantial length of the field exciter member, the curvature and physical positioning thereof being so selected that the near force field developed thereby is at least approximately proportional to the sine of m times the angle theta ; here m is an integer which is zero for one field exciter member and the near force field is magnetic, one for two fiEld exciter members, and two for four field exciter members, and where theta is the angle in cylindrical coordinates in the plane perpendicular to said longtudinal axis; and electric circuit means coupled to at least said one field exciter member and having an operating frequency related to the physical plasma characteristics in accordance with the following table:

2. A pulsating plasma device as claimed in claim 1 wherein: there are two of said field exciter members, the inner surfaces of said field exciter members are convexly curved, said electrical circuit means is a microwave circuit, and said oscillating energy is transferred through an electrostatic field.

3. A pulsating plasma device as claimed in claim 2 wherein said microwave circuit means includes a wave-guide having a rectangular cross-section, and said two exciter members are physically attached to opposite side walls of said wave-guide in electrically conductive relationship thereto.

4. A pulsating plasma device as claimed in claim 2 which further includes means for cooling said plasma column so as to maintain a substantially uniform temperature of the plasma throughout the length of said column.

5. A pulsating plasma device as defined in claim 1 wherein: there is only one of said field exciter members, the inner surface of said field exciter member having a substantially cylindrical configuration, and said operating frequency defined by the following table:

6. A pulsating plasma device as claimed in claim 5 wherein the value of Ai is 0.

7. A pulsating plasma device as claimed in claim 5 wherein C is the ion acoustic wave phase velocity, and is defined by the equation C2 (Ci)2 ( gamma ekTe + gamma ikTi + 2 omega Nu eme)/mi.

8. A pulsating plasma device as claimed in claim 5 wherein C is the electron acoustic wave phase velocity, and is defined by the equation C2 (Ce)2 gamma ekTe/me + 2 omega Nu e.

9. A pulsating plasma device as recited in claim 5 wherein said cylindrical field exciter is split along the longitudinal axis at one point and leads are attached to each side of said split cylinder for connection to said electric circuit means.

10. In a pulsating plasma cylindrical column having at least one field exciter member of substantial length positioned in spaced parallel relationship to the longitudinal axis of said plasma column for providing radial ion oscillations in said column said field exciter member electrically insulated from said column, said field exciter member connected to electrical circuit means for transmitting energy to and receiving energy from said field exciter member, said electric circuit means operable at definite frequencies, a method of optimizing the near field energy transferred between said field exciter member and said plasma column, comprising: selecting the operating frequency of said electrical circuit means and the physical characteristics C, sigma , ro and Omega of said plasma in accordance with the resonant frequencies as determined by the table: