** I OF I ORNL P. 1557 EEEEEEEEEE 17 MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF STANDARDS - 1963 LU 4 ' '. . f ki EDIT! X IT: . . is ine .: '*! 1. .:- W . 1,2 . - - . . 4 . . . . . . . . C A . LE isi : . . - - - 1 . .... LEGAL NOTICE This report was prepared as an account of Government sponsored work. Neither the United States, nor the Commission, nor any person acting on behalf of the Commission: A. Makes any warranty or representa- tion, expressed or implied, with respect to the accuracy, completeness, or usefulness of the information contained in this report, or that the use of any information, appa- ratus, method, or process disclosed in this report may not infringe privately owned rights; or B. Assumes any liabilities with respect to the use of, or for damages resulting from the use of any information, apparatus. method, or process disclosed in this report. As used in the above, “person acting on behalf of the Commission" includes any em- ployee or contractor of the Commission, or employee of such contractor, to the extent that such employee or contractor of the Commission, or employee of such contractor prepares, disseminates, or provides access to, any information pursuant to his employ- ment or contract with the Commission, or his employment with such contractor. .). 7 her • 1 : 2 , .. I . !. .. . I . . . . . .it . 1 . GE . . . . 1 ! . - . 1 . 1 1 1 3 ... . . 5 ORM P ** " :::; .. ROUGH DRAFT #2 8/3/65 CONF:650806 A STUDY OF THE PROPERTTES OF IONIC SOUND WAVES* SEP 21 1965 W. D. Jones and I. Alexeft 1 Oak Ridge National Laboratory Oak Ridge, Tennessee, U.S.A. TI ABSTRACT . " LY We have made extensive studies of the properties of ionic sound waves using a time-of-flight technique. The waves were propagated in collisionless plasmas formed by rare-gas discharges, with T. » T..We have investigated the following plasma and wave properties: wave... . . . velocity dependence upon ion mass, frequency and electron temperature; wave reflection; wave interference phenomena; wave gas damping; wave focusing; plasma sheaths; plasma con temperature; and the adiabatic compression coefficient of the electron gas. . P LY . :T . AA ! RELEASED FOR ANNOUNCEMENT IN NUCLEAR SCIENCE ABSTRACTS . .:. : :. *Research sponsored by the U.S. Atomic Energy Commission under contract with the Union Carbide Corporation. . 1 2- 1 - I. INTRODUCTION :: We have made extensive time-of-flight measurements of ionic : sound waver Hoo The waves are propagated in plasmas formed by low - pressure, rare-gas discharges. In these plasmas the mean free paths of the electrons are comparable to the dimensions of the plasma and T. >>T,. From the time-of-flight measurements we have determined the following properties of the waves and of the plasmas: - . Is The wave velocity obeys the dependence upon lon mass and electron temperature predicted by the Tonks-Langmuir theory. ... 2. The waves are collisionless, i.e., the adiabatic compression : coefficient y of the electron gas is equal to 1. 3. The lon waves are emitted and detected in sheaths about 10 Debye lengths thick. 14. The waves do not appear to be reflected: :5. The waves exhibit no dispersion: The waves are only slightly damped at Low pressures.. 7. The waves can be made to exhibit classical wave interference effects. 8. The waves can be focused: 9. The waves propagate in a rectilinear manner: 10. The plasma ions, as determined from ion wave Doppler shift measurements, are essentially at room temperature. YA. " I' 4 SET 9 15 . : : 27 _ 1 , 1 L S . : . II. EXPERIMENTAL APPARATUS, TECHNIQUES AND RESULTS . Figure I shows the apparatus typically used. The measurements are made in a spherical, glass discharge tube about 20 cm in diameter, with background gas pressures ranging from a few tenths of a micron 1 to a few microns. Rare gas plasmas are used. The plasma 18 formed by the anode-cathode assembly seen on the right. The ionic sound waves are propagated between negatively biased probes. The waves are generated at one of the probes...by voltage pulses, voltage steps, or sinusoidal voltage bursts. The arrival of an ion wave at the second probe appears as a perturbation of the ion current to this probe. Figure 2 shows some typical results. Figure 2(a) shows the detector probe response (upper trace) to step- function voltages (lower trace) placed on the emitter probe. Figure 2(b) shows, similarly, the response to a sinusoidal driving voltage, Note that in each case there is a directly-coupled signal on the detector probe. Thus a time-of-flight technique is needed to separate the driving signal from the received ion wave signal. III. COHERENT DETECTION Sometimes it was necessary to increase the signal-to-noise ratio of the received signal. This was accomplished by a coherent noise · rejection technique using a sampling oscilloscope. Figure 3 gives an example of the capability of this technique. We found increases of signal-to-noise ratio of 25-50 quite easy to obtain. IV. ION MASS AND ELECTRON TEMPERATURE DEPENDENCE : For plasmas having T. » Te, and in which the ion-neutral collision rate 18 negligible!" the theoretical phase velocity of loaic sound waves in a plasma is given by the Tonks-Langmuir formula, 1 V = (jk T) 1/2 m, -1/2 where y 18 the adiabatic compression coefficient of the electron gas, k is Boltzmann's constant, T. is the electron temperature, and m, is the ion mass. In earlier time-of-flight work, we have observed good agreement between experimentally measured wave velocities and those calculated using Eq. (1) "An example of our more recent time-of-, flight data is shown in Fig. 4. In this figure the experimental slopes velocities are given by the wipes of the curves. The velocity dependence on lon mass is immediately obvious.. V. COLLISIONLESS WAVES . : To calculate an experimental value for y, we used Eq«(1) with the known value of me and the experimentally measured values of velocity and electron temperature. Some typical results are shown in Fig. 5. Theoretically y can be 1, 5/3, or 3. The values of 1 and 3 should hold for collisionless waves if the waves are isothermal or : adiabatic, respectively. The value of 5/3 should hold for collision- dominated adiabatic waves. From Fig. 5 the experimental value of y.is seen to be near i. Thus, the lon waves appear to propagate with : T . . . . . . . . collisionless, 1sothermal compression taking place in the electron gas. The two cases shown in the figure arise as follows: For any set of experimental conditions there seems to be a critical discharge tube"." current above which we observe radio-frequency noise emitted near the calculated electron plasma frequency. This we call the "noisy" regime. Below the critical current the plasma is extremely quiescent and we . call this the "quiet" regime. The basic limitation in the reliability of the computed values: of y has been in obtaining reliable measurements of the electron temperature. We found that in all the gases studied except helium, the bulk of the electrons are trapped electrostatically in a potential well a few volts more positive than anode potential. These trapped electrons apparently thermalize at the slow rate given by collision processes. Consequently, Langmuir probes used to measure the electron temperature must be quite small in area, or else they drain away the trapped electrons so rapidly that the equilibrium energy distribution is distorted. In our plasma volume of 12 liters at a density of about 209 cm3, a cylindrical wire probe having an area of 0.06 cm apparently gives reliable results. . f VI. PLASMA SHEATHS Figure 4 shows that linear extrapolation of the curves gives a finite probe separation at t = 0. This is evidence for sheaths on the negatively biased probes. The total thickness of each sheath, Assuming the transmitter and receiver sheaths are equal, s, 18 about 7 to 10 Debye lengths. VII. WAVE REFLECTION walls as well as from . We have made many unsuccessful efforts to see reflections of ion waves. We have looked for reflections from glassa biased and unbiased metal wails. Figure 6 shows a typical arrangement used with a spherical tube. The emitter and detector probes are located approxi- mately at conjugate foci of the reflecting surface. This arrangement should virtually eliminate any 1/r" decrease in the ion wave signals. We estimate that we should be able to see easily a reflected wave having an amplitude only 1/1000th as large as the lon wave signals normal?y detected in ordinary propagation experiments, taking 1/r“. losses into account. Since no reflections are observed, we conclude that if the waves are reflected from solid surfaces, it is only very weakly. VIII. DISPERSION MEASUREMENTS Theoretically, it is expected that for frequencies far below the ion plasma frequency the ion wave velocity will be independent of frequency. As the frequency approaches the ion plasma frequency, however, the wave velocity is expected to gradually decrease to zerg.º. We have looked for this effect, using both step-function voltages on the emitter probe and sine-wave voltages\. So far we have not observed . the expected phenomenon. Instead the waves cease to propagate at a frequency generally about an order of magnitude lower than the calculated lon plasma frequency: The lack of dispersion is indicated in Fig. 7 . both by the lack of spreading of the received signal with increase in --- T he -- - - -- - * 15 , W. in . .1 * * . tid . ' 1 . 14 - 16.. . :- . v i. - *. * T A 11 .. path length and by the failure of the rise time of the ri:ceived signal to change appreciably. As noted in Ref. Ag,we may be seeing a sheath interference phenomenon occurring at a frequency below that required for the expected effect and thus preventing observation of the latter. 10 . IX. GAS DAMPING Amplitude measurements show gas damping, e-folding distances of 10 cm or greater. For the distances involved this signal loss is generally negligible compared to the signal decrease due to geomet- rical factors. The observed gas damping agrees well with that expected theoretically?4,1 For the low gas damping present in the system an appreciable slow-down of the ion wave is not expected. X. INTERFERENCE EFFECTS To demonstrate destructive interference with ionic sound waves · we used two ion wave sources and one ion wave detector, or, in other words, an "ion wave interferometer." By placing a positive voltage step on one emitters and a negative voltage step on the other, emitter, we could cause a compression wave and a rarefaction wave to: . arrive at the detector at the same time, thus leading to destructive interference. By varying the relative times of pulsing of the two 1 . emitters, probes, the interference could be made to take place gradually. This is shown in Fig. 8. In this slide the positive voltage step (midale Amdan. trace) was always imposed on the "upper" probe at the same time, relative to the time of scope triggering, giving rise to the positive 22 E- WN stationary pulse seen on the upper trace. The time of negative Amerter pulsing (lower trace) of the "lower" probe was varied relati's to this time, giving rise to the negative moving pulse seen on the upper trace. It is noted that maximum interference occurs not when the two prebes are pulsed simultaneously, but rather when the lower emitter : probe was pulsed somewhat before the upper probe. This is because emitir the lower probe was located further from the detector than was the .upper prote.. If instead of putting steps of opposite polarity on the two i emitters' one puts voltage steps of the same polarity on both emitter probes, then we see constructive interference at the detector rather than destructive interference. XI. WAVE FOCUSING Ionic sound waves are easily focused. To demonstrate this property we used a large concave emitter probe and moved a detector probe radially in and out of the optical focus of the concave i emitter. Figure 9 shows how the amplitude of the lon wave signal to the detector varied with the radial position of the detector. The data show quite clearly that the waves are focused by the concave emitter, probe. XII. RECTILINEAR PROPAGATION That ionic sound waves propagate in a direct line-of-sight manner 18 easily demonstrated. A metal plate just slightly larger in diameter - -- H .. than the detector probe was arranged so that it could be rotated . 77 þetween the emitter and the detector, thus "shadowing" the detector. . " Figure 10 shows the amplitude of the detected signal both with and without the metal plate between emitter and detector. The metal plate blocks the waves. 6: . - XIII. ION TEMPERATURE FROM DOPPLER SHIFT If the two probes are not place symmetrically with respect to the center of the discharge tube, the propagation times are not equal upon interchange of the roles of emitter and detector, as shown in Fig. 11. The lower curve is for propagation from a movable probe to a central probe - against the direction of plasma drift while the upper curve 18 for propagation in the opposite direction with the plasma drift. The Doppler shift in the propagation velocity gives the drift velocity of the plasma to the walls. The value obtained is only 15% of the ionic-sound-wave velocity but agrees closely with the velocity of thermal ions at room temperature. . XIV. SUMMARY In the simple apparatus shown here, experiments can be performed on ionic sound waves in a simple and routine manner. The waves may have many applications; for example, they can be used to measure the electron temperature and to infer the ion temperature in gas discharges. .-10- FIGURE CAPTIONS Fig. 1 Apparatus Used in Time-of-Flight Studies. Fig. 2 Production of Ionic Sound Waves: (a) The lower trace shows two voltage steps of opposite polarity as the driving voltages on the emitter probe. The upper trace shows the two corresponding ion waves, also of opposite polarity, arriving at the detector. Note the time separation of the ion waves and the initial transient signals due to direct · coupling between emitter and detector probes. (b) The lower trace shows a sine wave burst as the driving voltage. The upper trace shows the direct-coupled signal and the later- arriving ionic-sound-wave signal. Fig. 3. Coherent Detection of Ionic-Sound-Wave Signals in Argon. Sweep = 5 usec/cm; Pressure ~ 6 uHg; Propagation Path : Length - 7 cm. The upper trace shows the original ion-wave signal. The lower trace shows the same signal after coherent detection. Fig. 4 Time-of-Flight Data for Ionic-Sound-Wave Propagation in Rare-Gas Plasmas, Using Pulses. Times is measured from the driving pulse to the leading edge of the response signal. For the four heaviest gases the electron temperature was about 1 eV, whereas for He it was about 9 ev. .: Fig. 5" Gama (7) Values Determined Experimentally for Ionic Sound Wave Propagation in Plasmas Formed by Low-Pressure, Rare Gas Discharges. -11- Fig. · 6 Arrangement Used to Look for Reflection of Ionic Sound Waves Piir . From the Wall of a Spherical Glass Discharge Tube. To, O . IL: Fig. 7 .. Ionic Sound Wave Signal Detection in Xenon, Showing Lack of Dispersion. Sweep = 20 usec/cm; (a) Propagation Distance ~ 1.7 cm; (b) Propagation Distance *8.7 cm. The rise time and pulse width is the same for both cases, indicating no dispersion is present. Fig. 8 1 . Destructive Interference of Two Ionic Sound Waves in Xenon. Sweep = 20 usec/cm. For each picture the upper trace :shows the signal at the detector; the central trace shows a posi- tive voltage step applied to one, transmitter probe at a point constant in time, relative to the time of oscilloscope triggering; and the lower trace shows a negative step voltage 1. emitter applied to the other transmitter at a variable point in time. Note the progressive interference with essentially complete destructive interference shown by the upper right-hand picture. Fig. 9 Focusing of Ionic Sound Waves by Means of an Emitter Probe Having a Concave Surface. 1,, ... Fig. 20 Rectilinear Propagation of Ionic Sound Waves in Xenon. Sweep = 20 usec/cm. The upper and lower traces show the relative amplitudes of ion waves detected with and without, respectively, a metal plate obstructing the line of sight between emitter and detector. .:: -- . r. Pu nertava **'07. 2- Fig. 11 . Doppler Shifting of Ionic Sound Wave Velocity Due to Plasma Drift. The uppermost and lowermost curves are for ion wave propagation in and against, respectively, the direction of plasma drift to the wall of the discharge tube. The amount of the Doppler shift provides an estimate of the ion i ... . . . emperature. - - - . .. -13- - + . . 11 : REFERENCES 1. L. Tonks and I. Langmuir, Phys. Rev. 33, 195 (1929). 2. I. Alexeff and R. V. Neidiga, Phys. Rev. 129, 516 (1963). 3. P. Bletzinger, A. Garscaddej, I. Alexeff and W. D. Jones, J. Sci. Instr. 42, 358 (1965). . . 4. I. Alexeft and W. D. Jones, Thermonuclear Div. Semiann. Progr. Rept., April 30, 1964, QRNL-3652, Sec. 4.6 (available from Ollice of Tech. Services, U.S. Dept. of Commerce, Washington 25, D.C., Price $2.75). 5. I. Alexeff and W. D. Jones, Comptes Rendus de la vie Conference Internationale Sur Les Phenomenes D'Ionization Dans Les Gas, ed. by P. Hubert and E. Cremieu-Alcan (SERMA, Paris, 8-13 Juillet, 1963), Vol.; III, p. VI 36. 2 It 6. B. D. Fried and R. W. Gould, Phys. Fluids 4, 139 (1961). : : : : . . 7. L. Spitzer, Jr., Physics of Fully Ionized Gases, 2nd Ed. (Interscience, New York, 1962), Sec. 3.2. 8. L. Spitzer, Jr., op. cit., Sec. 5.3. 9. Li Spitzer, Jr., op. cit., Sec. 3.2. ... i ! 10. I. Alexeff and W. D. Jones, Bull. Am. Phys. Soc. 10, 509 (1965), Paper GHO. 11. Y. Hatta and N. Sat, Proc. Intern. Conf. Ionization Phenomena Gases, 5th Conf., Munich, 1961, vol. I, p. 478 (1962). . * 1. . - ... . . .... . - -- : . 1 . . . : - 1 -. . *.. . . .''! 2 arm.mm-mma USCULOSComt Thucer :S . . p pomidor MULSER *. KALE DISCHA sunt nec IMY BASED OVOLE LAOTNO M ALO WCER . . . ANODE .-. mo con WINT Xony " mo u MANENO MATEMAL ; ; vemenu or ochuco.com The Anne 1 - .. . . ' . + 1 J : 1 - .. 1 * K . 1 - 11 * 10.no 1 . 2 1 . 2 . . . .! 1 miria .. . :: FIG. 16 vrir 3 . * * - - - - ... ." Wh - . منتهی شد جر ... ر " r- هم و . .. I وب . .ا ,, واده : . ۔ ' ،' ::::۱ ب. ۱۰ / . . 1 ..:: - .... :::: * : و , ده م ... . . . ; :: , : * * نیم شم . ::::::: .... نمنح مهمه .:: .: :. من رد ہے : وم ما k '' : ا : X ..:: بنایا۔ | | اال . .. اذا ما ه نا ' f '. ء أن , هم . .. :: :: ا :: . II . :: .. . فيها لما . . و " . .. .. ا : .. . ,ار اما اور و . الم جه .... اله : . : نم 4: 41 نی ابا 10 1: بع . |- H ۱۱ :::: :الوثيه او و وه و | | ا نت * .. : ::: اد * .. | زا : A وان / دو 47 وا ::::::: I 11 : 41 خانه . 1: مام : I * . T ا :: ::: . . 2. او : :: :: : .لا اج + | | ' :اب: الان م ار | ! کالا :المدة . | | ات انو موت مد بک * :. .مم :.... . انه ... ، . : لی ده و . دانا جع ... ) (1 بی بی به اند انن ذه ومن ریم :: . و در بن عبد من . .. .. .. .. .. .. .. .. .. .. .. .. :: وه و حصصهم . . تراف مهمت . . اه :: :: :: :: :: مد و ای و 11 * III * الا * - : مر ولا دوا ان | , ج , - هما . ها و الهام یادوں امور i ما وام و 1 M . ها ، 11 !!! با ده ام ما ل ا = مه: دد U = هه و 4 ان : ۶۰ تا ::: ::: ::: المال E 11 • بممننننتننتانتنت سرد :: ۰ H ; ازة تن تن کی * : :: من 1:: معامل :. : ۰ :: : : نر ۰ = نانو اب دو؟ ۰۸ مان اا ادا اه I حا با ما رو 1 :الان ا زا .. 1 . - م دارم . ام .: LIE ST. TEN .1.1 :- . . - - . . . : .... INERT 7817 ÄN PAISON 19373... ::PHOTO 6.800ų : .. - . d 1. TI 1 . . IN . TEL . TI . O 191 UD * 1 . . . . . . . K IS D . 1 HR . AU IN OM 11 ! 11 1 1 . . NSW . . 1 + T 1 . ! DISTY 0 715! . ' L . I 1. . 1 NIN 1. I JI 11 11 N f . 11 - . 1 2 RU 171 WW MT TA 1. IPC 2 . .Iy . # 17. LT 1 . 7 . 1 . 11 2 0 11 . V 1 . 1 SH 1 . L I ! CE . 19 are 1112N ER 2 S . YI . * . . V ! UN I VAN Wind 3 NY . . T. 11 11 11 DI S 1r 1:11 . Itt . 117 . Tz 11 • . 14. Sant I II. A 11 US . WUXIL AI . . 11. S. - Y . C ar . 1 1) 13 HU. ! NUEVA Y tit OT VITA w MANUEL 20 MI UTI Re: P DIA 11H / 1 HUI IN . VI 312 YA 11 . ! . . 11 INNI 11 VEIS . CO DAL WIU TO KIT MAN ki . nu ur' 11 . T CH . 31 + IS ET .. T . PAS R - .. . i1...,16. $ 1 1 : . . . 1 . * . . . - '.. . - - - : . ... PROBE SEPARATION (cm) . . . . ... 0 . . . .. .. . 9 / ۱ 2040 60 90 PROPAGATION" TIME (usec) - 100 120 140 160 180 کی ا مان۔ : . و . . . 1 ا : ک * قد ار : . . ::. : ا . . = . ..:: .ن، نه .م . ه ". م . .... wh - - e . .. t - e dominantemente in a manteniment --•. • -.. . . . - - ', -* in en handlingen - - - with a woman wine and . --- - - - ...... .. . ... . -• - - ---- -.- - - . has continental me - - - d .. - t. * .. - - 1 - 5 :: ORNL-DWG 65-7673 100 200 : aq A PRON Ne ::. "NOISY" PLASMAS 40. IONIC MASS → 10 4' 0 "QUIET". PLASMAS TOTT 100 200 :::40 IONIC MASS - "10:: FiGSE VALUE OF y vs IONIC MASS 4 .: . : M.,::: ... ", " ... - . [ - .... * NY . TO IL _ 1" - TV UT 4 1 . ... 2 . IL . 12 . . .. . RA ORNL-DWG 65-4602 - . : ... .. : : :: - ION-WAVE REFLECTION EXPERIMENT . B . . 1. -. . i - - . 1 . . " 3 2 - . PLASMA SOURCE OSCILLOSCOPE IA|DETECTOR EMITTER KWH PULSER . 1 . 1 . . .. . . ...... - . 1 3 . . . *. -REFLECTING SURFACE . 2 . * . . .. ". . Y . . : 1. ..' 7 . T . .. .- 1 + - i.. FIG. 6 . . . 1 . PHOTO 80317 :: . . . . 1 - . X ..... .. - ,! . . B . : i : ..iiin.. . . . 1: YO . . . " . . . . M E . . . C 11 ! ! n ir la) : . 14 . :.: :::::::: L .... n IN ...i IT . . 1.In : NA . : . . . i . . 1 11 4 * A itri 'ir TJ P .. f tur: ! .. ! *. 1 1112 . VO! re . RA, 2 . NI .. . A . LI .. 17 . 2 . 19 ' 2:33 101 . . . WINE 19:II .. NI IS * O i NN - 14 T S Siirt . - S41 (6) JONIC - SOUND - WAVE SIGNAL DETECTION IN : XENON, SHOWING LACK OF DISPERSION. . SWEEP = 20 hsec/cm; (a) PROPAGATION DISTANCE $ 1.7 cm; (b) PROPAGATION DISTANCE ♡ 8.7 cm. FIG. 72 ' . ' '. : Skirtshallen . . P-6117 . . A ...... 1 DESTRUCTIVE INTERFERENCE OF ::ION WAVES AT THE DETECTOR . . " PAR 2 2. " T 10 . ss Otsi . LI stor internet : 13761 " . 1 .. " .. . 1.5, : . . . C . S . ... m The roo i V Hiina RES wint w t he best and n iital ** 1 V SN * 2011 - 11003 HI PIX . tres .. . he W HAU . 61 CE he 1 3 ili Hifi nn, m.. Hiu A * E *** ! . 11:11 I HE um Witam AWM Wila. Puh 14 Watu Nov . BE . 1 + 1 .. CA Ur', MI ** COM * prima i BE ni Al l !::..:;; *•, "..." 1' :::..... 101 . . ... t111 2 CS bushe . L A - - TS .. 11 1 26 IT . 17:1, II. . OYO Ei 1 .. . S2 TV 111 . ::;?!.." Pu 7 Swedi. id RE : SA She 1 . 19? 11 1,! !. !! s 22 LUX 11 pel . i *. FIG Å - : : .. ORNL-DWG 65-3506 20 :: . ...:::-- -... : : ; DETECTOR SIGNAL AMPLITUDE (ARB. UNITS) .: :: 3. :: ootttttttttt :57 0 1 2 3 4 5 6 7 8 9 RADIAL DETECTOR POSITION (CM)- FOCUSING OF ION WAVES FIG.91 . .. ? | , '' , ! * : :"; ', '' : । : { 4. }} : : : : 7. 1 : 97} !!} .. ! *1. 7 ރާއްހީ * St." R * * * .. ** - 7!:p ? * : . - * 143 :** * . : : : .. # 1 * 4, 30% ,, : # 1 } ' 111 * * By: ' ":::: •••• . :';"' , ** 17:4 -10 t : k th ਆ 4 : }} + By:41:* * 7 ਨ , that ** * ॥ } * . P : i } ' ::: ! 1 * ! * . 12 M . : , * 4} : * Hi : 1414 . * } ਕੀ * 115 ::: :: 7 : . । : '. 2 * * * : s : · ** . : *} 2017 4. ' ' ' # . ਮ: 1 . / . ' • e . ::" : ( ' ਨੂੰ " r ਨ " ਮਾਂ" . / . ilk :: :/ 4:07. . :: , F/G. / * : s . :- * . : * : : n ht + : 7 ॥ : : ::: : :: ::::: A । : ' | . ਦੇ ॥ . ::: 4 . ਜਾਂ :- : - : . :: : .. 1. ਏ r 11: 37 :::::: : 1:- i 1 * 1 * " " । : :: " :::: : 1:"::: : : : t : , s ਨ ## , Bh * '""''". . { ' ' | . ::: : " , } 14 : th, ♥• 1}{ ਆ ਖs ੧ F ::: S * * s i * " । , · ..: :: .. . * :: ::: 63. * :: :: ' , . - ::: 1:17. 3 .... ਨ ::: . :... : : * 8 s: • * , * 1 : : . . 1 . . '' , ' .: •• . ਮਾਂ : , + " : : * * | . ਨੇ . 13 .. ! !! . 3 . ੪ ; . ..' E * * a : . in 1. ਨੇ . wen - " .. . . . . . ORNL-DWG 65-2698 AVERAGE VELOCITY=1.08 x 10 CM SEC - (THEORETICAL VELOCITY=1.13 X 10 CM SEC ASSUMING 8 =1) de :: .. . ..- en PROBE SEPARATION, CM A:: W. No .. . Dr . Anschirm A=ION WAVE PROGRESSING FROM J CENTER TO EDGE OF TUBE. O=ION WAVE PROGRESSING FROM EDGE TO CENTER OF TUBE.s. - -.- -.- ; . ::::: 10 20 30 40 50 60 70 PROPAGATION TIME, U SEC. DOPPLER - SHIFT OF ION-WAVE VELOCITY DUE TO PLASMA DRIFT .. and FIG / . if,, END 2 ) - .. . 1 DATE FILMED - 10/14/65 . * 41.. - - I.