THE UNIVERSITY OF MICHIGAN ANN ARBOR, MICHIGAN QUARTERLY PROGRESS REPORT NO. 14 FOR RESEARCH AND DEVELOPMENT ON HIGH-POWER CRESTATRONS FOR THE 100-300 MC FREQUENCY RANGE This report covers the period October 1, 1963 to January 1, 1964 Electron Physics Laboratory Department of Electrical Engineering By: G. T. Konrad Approved by: 4 C. K. Rhee G. T,. Kornrad t Project Engineer J.. Rowe, Director Electron Physics Laboratory Project 03783 NAVY DEPARTMENT BUREAU OF SHIPS ELECTRONICS DIVISION CONT RACT NO. NObsr-81403 PROJECT SERIAL NO. SF0100 201 TASK NO. 9294 January, 1964

ABSTRACT A series of trajectory plots is shown which led to a reasonably good electrical design for the P = 20 gun. The work done on the electrostatically focused tube using a P = 4.46 gun indicates that much better focusing can be obtained with the improved gun. At reduced voltages the beam transmission is only fair but it is shown that the percentage of transmission is improving as the design voltage is approached. In order to center the operating band of the 100-watt Crestatrons more nearly within the desired frequency range and in order to overcome the r-f losses observed in the couplers, a revision is made in the tube design. The new dimensions and electrical parameters are shown. -iii

TABLE OF CONTENTS Page ABSTRACT iii LIST OF ILLUSTRATIONS iv LIST OF TABLES vi PERSONNEL vii 1. INTRODUCTION 1 2. COMPUTER DESIGN OF HIGH-PERVEANCE HOLLOW-BEAM GUNS 1 3. EXPERIMENTS ON THE ELECTROSTATICALLY-FOCUSED HOLLOW-BEAM TUBE 10 4. WORK CONDUCTED AT THE BENDIX RESEARCH LABORATORIES 10 4.1 Experimental Data on Tubes 10 4.2 Summary and Evaluation of Tube Performance 19 4.3 New Electrical Design, TW-147 21 5. SUMMARY AND FUTURE WORK 23 -iv

LIST OF ILLUSTRATIONS Figure Page 2.1 Trajectory Plot for Electrostatically Focused P = 20 Gun. (J =3.732 x 103 AMP/I2 P 18.017) 3 2.2 Trajectory Plot for Electrostatically Focused P = 20 Gun. (J = 3.813 x 103 AMP/m2 P = 18.397) 4 2.3 Trajectory Plot for Electrostatically Focused P = 20 Gun. (J = 3.811 x l03 AMP/m2, P 18.388) 2.4 Trajectory Plot for Electrostatically Focused P = 20 Gun. (J = 3.726 x l03 AMP/m P = 17.991) 6 2.5 Trajectory Plot for Electrostatically Focused Pi = 20 Gun. (J = 3.698 x 103 AMP/m P = 17.854) 7 2.6 Trajectory Plot for Electrostatically Focused P = 20 Gun. (J = 3.722 x 03 AMP/m2, P = 17.97) 8 2.7 Trajectory Plot for Electrostatically Focused P 20 Gun. (J = 3.751 x 103 AMP/m2,P = 18.10o) 9 3.1 Beam Transmission vs. Beam Voltage. 11 4.1 Power Output Characteristics of TWT-143-A-14 (I = 400 ma). 14 K 4.2 Power Output Characteristics of TWT-143-A-14 (IK = 300 ma). 15 4.3 Power Output of TWT-143-A-15. 16 4.4 Comparison of Insertion Losses of Tubes No. 13 and No. 14. 17 4.5 Computed Power Level on Helix in TWT-143-A-15. 18 4.6 Insertion Loss of TWT-143-A-15. 20 4.7 Cross Section View of TW-147. 24

LIST OF TABLES Table Page 4.1 Physical and Electrical Parameters of Tubes Tested 12 4.2 Physical and Electrical Parameters of TW-147 22 4.3 Design Parameters of TW-147 22 -vi

PERSONNEL Time Worked In Scientific and Engineering Personnel Man Months* J. Rowe Professor of Electrical Engineering.20 J. Boers Associate Research Engineers.88 G. Konrad.93 W. Rensel Assistant Research Engineer.47 C. Rhee Research Assistants 1.58 D. Terry.40 Service Personnel 9.53 *Time Worked is based on 172 hours per month. -vii

QUARTERLY PROGRESS REPORT NO. 14 FOR RESEARCH ANJD DEVELOPMENT ON HIGH-POWER CRESTATRONS FOR THE 100-300 MC FREQUENCY RANGE 1. Introduction (G. T. Konrad) Contract NObsr-81403 comprises a research and development program on high-power 100-300 me Crestatrons. The aim is to construct compact 100-watt Crestatrons employing permanent magnet focusing. Initially the tubes will be tested in a solenoid until they meet electrical specifications, but ultimately the permanent magnet focused tubes employing a depressed potential collector will be ruggedized so as to meet environmental specifications. This work is being conducted by the Bendix Research Laboratories on a subcontract from the University of Michigan. Theoretical as well as experimental studies on high-perveance hollow-beam electron guns, in addition to electrostatic focusing systems initiated some time ago on this program, are being continued by the University of Michigan. The ultimate goal of these studies is to demonstrate the feasibility of using electrostatically focused, highpower, hollow electron beams in microwave devices. In addition, it is intended to work out a design for an electron gun compatible with a high-power vhf Crestatron. 2. Computer Design of High-Perveance Hollow-Beam Guns (C. K. Rhee) The first set of beam trajectories for the P = 20 gun shown in *-i the last quarterly report indicated the necessity of a stronger focusing lens in order to overcome the large space-charge forces within the

-2the electron beam. Since the focusing action does not penetrate into the beam deep enough with the present lens electrodes, a modification of the shape of the lens electrodes is suggested. A series of figures (Figs. 2.1 - 2.7) shows the various stages in the modification of the lens-shape during the past quarter. Figure 2.1 shows a great improvement eliminating the gun region interception entirely. However, the degree of beam trajectory crossing is increased due to overly strong focusing action at the beam edge, as expected. In Fig. 2.2 the lens-shape was changed in such a way that there exists a stronger defocusing force, and hence the amount of trajectory crossing is somewhat reduced. In Fig. 2.3 the last anode was opened up a little with the anticipation of a stronger defocusing action at the beam edge, but there is not an appreciable change in the trajectory crossing. In Fig. 2.4 the lens-shape was changed to enhance the defocusing action and the last anode was closed back to the original position. The beam trajectory crossing is seen to be much improved but still it is not good enough to assemble a gun. In Fig. 2.5 the lens voltage was reduced V V o O from 10 to 1O-' but the trajectory crossing is enhanced due to a very strong lens action. In Fig. 2.6 the lens electrodes were moved away from the beam and the last anode was opened again. There still exists a small amount of trajectory crossing. In Fig. 2.7 a further removal of the lens electrodes eliminated the trajectory crossing completely. Although the beam interception and trajectory crossing have not occured in the gun region the beam as a whole is diverging and interception would take place in the interaction region. In this respect Fig. 2.6 has a potentially better transmission even though there exists a small amount of trajectory

-30.6 V vo / 10 V 0.5 0.4 0.3 CATHODE ——.- -— __ 0.2 FOCUSING A l l WFIRST| LENS I 1 LAST ELECTRODE ANODE ANODE 0. 1 0.2 0.3 0.4 0.5 0.6 z in inches FIG. 2.1 TRAJECTORY PLOT FOR ELECTROSTATICALY FOCUSED P 20 GUN. (Jo = 3.732 x 103 AMP/m2,PA = 18.017) o ~z~~~~~~~~~~~~~~~~~~J

-40.6 Vo Vo/10 Vo 0.4 0.4 0.3 ATHOD E 0.2 FOCUSING FIRST --- LENS LAST ELECTRODE ANODE ANODE 0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 z in inches FIG. 2.2 TRAJECTORY PLOT FOR ELECTROSTATICALLY FOCUSED P = 20 GUN. (Jo = 3.813 x 103 AEP/m2, P = 18.597)

-50.6 0.5I I I Vo/I Vo 0.4 0.3 CATHODE 0.2 FOCUSING -FIRST - - LENS L —LAST ELECTRODE ANODE ANODE 0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 z in inches FIG. 2.3 TRAJECTORY PLOT FOR ELECTROSTATICALLY FOCUSED Pa = 20 GUN. (Jo = 3.811 x 103 AMe/m2, P = 18.388)

-60.6 Vo V0/IO Vo 0.5 r 0.3 ATHODE 0.2 FOCUSING -- FIRST —- -- LENS - LAST ELECTRODE ANODE ANODE 0.1. O 0.1 0.2 0.3 0.4 0.5 0.6 z in inches FIG. 2.4 TRAJECTORY PLOT FOR ELECTROSTATICALLY FOCUSED P, = 20 GUN. (Jo = 3.726 x 103 AMP/m2, P, = 17.991)

-7-. 0.6 vo vo/ioo Vo 0.5 0.4 —j ELECTRODE ANODE 0.I 0.-0.2 0.3 0.4 05 0.6 0 0.1 z in incheS FI'G. 2.5 TRMECTORY PLoT FOR L.CTROSTATCAY FOCSE FI.20GUN (J 5.69 ATR/m2, = 17 854) 0~~~~~~U 0.1 3.69 x 0.3 AM0.4'PV

0.6 0.5 00 0 0.4 0.3 0.2 FOCUSING FIRST —m — LENS - - LAST ELECTRODE ANODE ANODE 0.I 0 0.1 0.2 0.3 0.4 0.5 0.6 z in inches FIG. 2.6 TRAJECTORY PLOT FOR ELECTROSTATICALLY FOCUSED P = 20 GUN. (J = 3.722 x 103 ANP/m2, P = 17.97) [o.

0.6 0.5 0.4 0.3 CATHODE 0.2z in inches FOCUSING FIRST ELECTROD ANODE LENS LAST ANODE 0.1,?"-0. 0.6 z in inches FIG. 2.7 TRAJECTORy PLOT FOR EC0 STAICALY FOCUSE P =20 GUN. (Jo = 3.751 x 103 AMP/m P 18.109) A~/~2 8.Ao

-10crossing. The final gun will be built using the geometry of Fig. 2.6 during the coming quarter. The other P = 20 gun with a smaller mean beam radius has been programmed, and the initial run was made. The major portion of the design of this gun will be completed during the next quarter. 3. Experiments on the Electrostatically-Focused Hollow-Beam Tube (C. K. Rhee) The vhf electrostatically focused Crestatron was repaired and reprocessed. The initial focusing test was conducted up to a beam voltage of 900 volts, which is still considerably lower than the operating voltage. Figure 3.1 shows the beam transmission vs. beam voltage. Although the transmission is poor at this stage, Fig. 3.1 shows that it is possible to get a much better beam transmission as the operating voltage is increased. It is expected that at the design voltage of 1500 volts the transmission will be quite good. The beam current density started decreasing markedly at approximately 800 volts due to a pressure rise within the tube as various parts became hot. In order to overcome this difficulty it may be necessary to pulse the beam voltage in future tests. 4. Work Conducted at the Bendix Research Laboratories * 4.1 Experimental Data on Tubes. Seventeen tubes have been completed to date. Twelve have been r-f tested and one is undergoing r-f tests at the present time. Table 4.1 lists the more important physical and electrical parameters of the tubes. Detailed data on the first thirteen tubes has been presented in previous progress reports. * This material was submitted by K. C. Earl of the Bendix Research Laboratories.

50 40 I- TRANSMISSION THROUGH ELECTROZ STATIC FOCUSING STRUCTURE L 30'- I 2O z C A, (OVERALL TRANSMISSION 10 m 03I I I 400 500 600 700 800 900 1000 BEAM VOLTAGE, VOLTS FIG. 3.1 BEAM TRANSMISSION VS. BEAM VOLTAGE.

PHYSICAL ELECTRICAL SPECIAL NOTES TUBE MATCHING SECTIONS BEAM DIA. RATED OPERATING NUMBER n~~~~~~~~~~~~~~~~~~~~~~~~~~~~ELIX RATED RATED CONDITIONS NUMBER OVERALL HELIX HELIX MEAN HELIX WIRE TYPE R.F. GUN INCHES COLLECTOR AE CONDITIONS LENGTH LENGTH DIA. (IN.) TPI SIZE CONNECTORS TYPE EN TYPE OUTER CURRENT EAM EAM SIZE ~~~~~~EACH END Inn ER OUTER CURRENT VOLTAGE TAPERED WT.143.Al~-1I 16 9.6 U.756 11.5 o ~ ~COAX DIRECT OUTER' HOLLOW 07 0n 45 R7X 105 680 GLASS TO KOVAR RF FEEDTHROUGHS PIN. COmN. SBEAM AND STEM HEADER SHIELD TAPERED OLLOW TUBE NOT COMPLETED DUE TO T-143A. 16 9.& 0.756 11.5 0o COAX DIRECT HLO TWT143A2 16 9.6 0.756 11.5 U0.U03U N COA C. OUTER 4" 0.478 0.590 452 l70... DATA ON TWT. 143-A-1 INDICATING PIN COWN. BEAM SHIELD CHANGE OF PLANS COAX DIRECT TAPERED ThIS TUBE DEVELOPED A' HOLLOW T I U E D VLPDA TWT-143-A.3 16 99 0.756 0.030 PIN CON. OUTER 4" BEAM 0.8 0.590 452 70 143 700 OPEN INNER ANODE AND ARC SHIELD BEAMBREAKDOW COAX DIRECT TAPERED HOLLOW TWT-143.A.4 11 5.6 0.756 10 0.030 PIN co OUTER 2" BEAM 0.478 0.590 452 350 R30 ULTIMATE AILURE O SHIELD LEKE I UN TAPERED HLO TWT.143-A.-5 I1 5.6 0.756 10 COAX DIRECT TOAPUREDHTERLL T 1 1 5. 1 0.030 2OUTER H' 0.478 0.590 452 70.... HEATER FAILURE BEFORE PIN COHN. SHIELD BEAM DATA WAS OBTAINED 10 TAPERED HELIX CONNECTION TO RI TWT.143. A-6 11 5.6 0.756 TAPERED 0.030 COAX DIRECT OUTER HOLLOW o.a 0.590 452 070 ECT —- IhEOUGH PAILED DRIN P)H corn. ~~~~BEAM TO 20 PIN COH. SHIELD BEAM BAKEOUT i0 TAPERED COAX DIRECT TAPERED HOLLOW HEIX APED TOO MUC TWT.143.A.7 11 5.6 0.756 TAPERED 0.030 OUTER 2. 0.47 0.59 452 370 200 490.560 HELIX TAPERED TOO MUCH. T0 PIN CONN. ELD BEAM RF PERFORMANCE WAS POOR TO 20 SHIELD 10 TAPEREDI COAX DIRECT TAPERED HOLLOW PEST TUBE TO GIVE TWT. 143-A-9 11 5.6 0.756 T APERED 0.030 PIN CONN. OUTER 2 BRAN 0.470 0.590 452 370 400.1770 100 WATTS SHIELD 11.5 STE ECHED OAX DRECTTAPERED TWT.143.A-10 I11 0.6 0.756 OUTPUTCE 0.030 OUXDIET TAERE.* HOLLOW 041 0 59 452 070 250 "o-940 OBTAINED MOMENTARY 1 ______ ~~~~~~~~~~~MATCH SHIELDOP60M TWT-143-A-9l 11 5.6 0.704 1. 0.030 C ADIETTAPERED2, tT1-l-13 COAX DIRECT TPRDHOLLOW FI RST T UBE TO GH AILUVE 5.6 0.7R 0.030 PIN COM. OUTER 2" 0 478 0.590 452 870 BAKEOUT EVERYTHING L PIN~ ~ ~ ~ ~ ~~~~~~~0 478 0.59 45 00 40.1 100 WATTS SHIELD EAM 11.5 STRELTC HED TAPERED H OLWOBTAINED WM4~ETAR Y I Ks TW'r. 1,1.-l~l 11 1 10.6 1 0.050 COAX DIRECT TAPERED HOLLOW TW143A1 11 5.6 0.756 OTU TT13A1 56 076 UNIPORM 030 PIN COHNN OUTER BEAM 0.478 0.590 452 870 150 680-9.40 P AI CATHO SHIELD15MAMAIUCAhDCURN TW.13A. 113 COAX DIRECT TAPERED HOLLOW 200 MA, MAXIMUM CATHOD TWT-143-A-13 11 5.6 0.756 UNIPORM 0.050 PIN COHN. OUT ER 2" BEA 0470 5.590 452 370 203 625.040 CURREN4T OBTAINED ~MATf~CH~ ~ SHIELD TAPERED 2' TWT.143-A.14 11 5.6 0.756 13 0.030 COAX DIRECT SHIELD twT~ I~~~~~~~-lr-ll I 11 5.6 1J COAX # Rt~~~~~~~~~~~~~~~~~~~~~~~~~~t ~HOLLOW RF FEEDTHROUG;H FAILURE DURING UNIFORM PIN COHN. OUPLED MCOUPLER DEGRADED PERPO SHi ELDX TAPERED I COAX DIREC~TAPHERED 2 HLO110 SEVERE INVERSE OVERLOA rTWT. 143-A.15 14 7.7 0.756 13 0.030 COAX DIRECT ED HOLLOW POOR ACTIVAT70 600 14 HIGH LOSS IN OUTPUT HODE, UNIPORM 0.030 PIN COHN. COUPLED 2" COUPLER DEGRADED PER 11 5.6 0.754 o. O#) OUTER r' ~~~~~~~~~~~~~~~~0.478 0.590 452 8170 150 580.700 UnlFORM Pin C~~~~~nn. ~BEAM 150 MA, MAXIMUM CATHODE CURRENT SHIELD ~~~~~~~~TAPERED~~~~HIGH LOS DEGRADED TWT.143.A1 13 6.6 0756 11 0030 COAX DIRECT COUPLED H1OLLOW 200 PEMAR ORMAXIMUM CE;DATHODE UNRIPORM PIN c03O UTERX 2" BEAM 0.478 0.590 452 o 00 DEPRESSED U~~lrORY PIW can. SmCLD ~~EAM CURRENT OBTAINIED TAPERED 2" 11 11 0.030 ~~~~~~~~~~~~~~~~ ~ ~~~~COAX DRECT SHIELD HOLLOW HIGH LOSS IN OUTPUT -F R CO-N. -'-OTNLTD IAL COLLECTOR TABLEm 14. 1 PHYSICAL AND KLC A 0.478 0.590 452 17P0IESOTUBES TE STED 2" ~~~~~~~~~~~~~~~~~~COUPLER DEGRADED PER IRDRMNCE _ ~~~~~~~~~~~~~~~~~~~HELIX TAP~~~~~~~~~~~~~~~~~~~~#H LS EGRAED tn~~~~~~~trll. u ~~~~~~~~~~~~~~~~11 COAX DIRECT SHIPE LD'' HOLOW 1140 E OMN;DT 14 7.7 0.756 0.030 1.I 050 42 n 0 UNIFO R M PIN CONN. COULI EDM C1 OIUPLERO DEGRADED 1PEFRAC B~~~~~~~~~~~~~~~~OEANA CLECO TABLE 4.1 PRYSICAL PWD ELECTRICAL PARAMETERS OF T0.40 0.590 42 870 60

-13Tube number 14 utilized an 11.5-TPI helix 5.6 inches long, a triode gun, and a coupled helix output matching section. Figures 4.1 and 4.2 show plots of power output vs. power input for this tube. The gain, power output, and efficiency are less than the average values obtained from previous tubes, and the optimum efficiencies ranged from 10 to 14 percent as compared to a general level of 18 to 21 percent for previous tubes. The reduction in performance appears to be due to the increased insertion loss of the coupled helix output coupler. A comparison of insertion loss between a tube with two tapered matching sections and a tube with one tapered and one coupled helix matching section is shown in Fig. 4.3. The figure shows that the interaction efficiency is apparently equivalent for the two tapes of output matching sections. A new multi-electrode gun was then incorporated into the tube, but the heater failed prior to r-f testing. Tube number 15 contained a coupled helix output coupler and a tapered matching section at the input. The 11.5-TPI helix was 7.7 inches long. This tube had a tendency to oscillate when operated at high beam currents with low beam voltages. Maximum power output was observed at these high voltages where the inverse overload characteristic of the tube occurs. Figure 4.4 shows a plot of power output vs. power input, which illustrates this type of operation. The coupled helix output coupler of tube number 15 had an average insertion loss of approximately 3 db, reaching 8 to 9 db at some frequencies. Figure 4.5 shows the insertion loss of the tube vs. frequency; in addition, the insertion loss of the coupled helix coupler is also plotted at several frequencies. An indication of the r-f power generated by the circuit can be obtained by correcting the output power

1001 IK =400ao ttI f Vv 16Tn1 d~ 13d IK:40 m-13 I ISOL = 5.8 Ioo 930 - IA = 11 - 16ma 150 930 6 db 200 990 IH =I. 55-7.0 mo 250 940 900 i 300 960 10 Or db II1.0 -300 MC -.. 200 MC 0'250 MC 0.1 0.01 0.1 1.0 10 PIN (WATTS) FIG. 4.1 POWER OUTPUT CHARACTERISTICS OF TWT-143-A-14. (IK = 400 ma)

-15100'K =300ma _o - i~~~~~~oo 6so....0l I$L =4.8A SOC 4.8 A 150 620 I/ -A= 8.0 - 10 MG'A 80 10m@ 200 620 IH = 6.8-8.5 ma 250 620 - 300 640 10 1.0 0.1 0.01 0.1 PWR IN 1.0 10 (WATTS) FIG. 4.2 POWER OUTPUT CHARACTERISTICS OF TWT-143-A-140 (I 300 ma) 10- - - /. [I_ ——.,. K

-16= 100-' _ _ _ _ _ _ _ _' l....'.. I'~ i~ TWA 143 A - 15 Vo = 1140- 1240 IR = 600 30M = I 7.1 - Al= 40 _ IA2= 11 - 1! I AI:= 70 I- II C9 it~~I2 I! 0/,,Mc " 0 1.0 -U~~~~. IH = ~~~~~~~~~25-:0 //c// O~~~~~~O,o 0.10......~~~~~50m 13 d 10 d 00 200 m c 6 dbbY 3~ d 0 db~ l 11 0. I 0.b 0.10 1-0 10 POWER IN-WATTS FIG. 4.3_ POWER OUTPUT OF TWT-1j-A-15.

A. INSERTION LOSS OF TUBE #13 CONTAINING TWO TAPERED MATCHING SECTIONS AND 5.6 INCH LENGTH BETWEEN INPUT AND OUTPUT, S. INSERTION LOSS OF TUB E #14 CONTAINING ONE TAPERED MATCHING SECTION AND ONE COUPLED HELIX MATCHING SECTION WITH 5.6 INCH LENGTH BETWEEN INPUT AND OUTPUT. 10 2100 120 140 16 0 180 200 220 240 260 280 300 320 340 FREQUENCY (MC) FIG. 4.4 COMPARISON OF INSERTION LOSSES OF TUBES NO. 13 AND NO. 14.

1000 _ V = 1140- 1240V.... I K = 600 MA. -_. __. _ -.... I SOL= 7.0 AMPS........-........ I Al = 40MA -. _ __-.. - X I A2 = 10 MA. I A3 = 50 MA IF- 100 FIG....................................... 4. C 600 MA - 100 125 150 175 200 225 250 275 300 FREQUENCY - MC FIG. 4.5 COMPUTED POWERh LEVEL ON HELIX IN TWT-143-A-15.

-19upward by the amount of the output coupler insertion loss. Figure 4.6 shows a plot of the computed r-f power level on the circuit vs. frequency. Tube number 16 used coupled helix couplers at both the input and the output. The resultant high insertion loss degraded the performance of the tube to such an extent that no new useful information on r-f performance was obtained. However, tube number 16 contained a depressed potential collector assembly and successful r-f operation was obtained with the collector operating at 3Vo/4. In addition, a noticeable decrease in the interception current on the third anode of the electron gun was observed, which indicated that the depressed collector allowed fewer secondary electrons to enter the interaction region. 4.2 Summary and Evaluation of Tube Performance. The maximum sustained power output thus far has been 105 watts; this was obtained with tube number 9 operating at 300 mc. An output variation of 40 watts occurred across the band from 100 to 300 mc. Tube number 10 produced an output of 140 watts at 250 me, 110 watts at 200 mc, 85 watts at 150 mc, and 40 watts at 100 mc, when operated with a cathode current of 600 ma. These data were obtained by pulsing the current to 600oo ma, since the tube could not be operated continuously at this current because of a gradual decrease of cathode emission. Tube number 15 had lower power outputs but the r-f interaction was good and the power level corrected for output loss was above 90 watts from 110 to 300 mc. This tube had severe inverse overload characteristics, however, and improvement of small signal gain is required. In addition, all of the tubes have been centered high in frequency. It was thought at first that the low frequencies were not amplified as much as the high

12 2 L I I_____ I_____ I__ I__I _I I 1 I = INDICATES COUPLED HELIX LOSS 10 0. 6 100 120 140 160 180 200 220 240 260 280 300 320 FREQUENCY - MC FIG. 4.6 INSERTION LOSS OF TWT-143-A-15.

-21 - frequencies because of r-f mismatch degradations in the low frequency range. However, it has since become apparent that the r-f structureelectron beam configuration design caused the tubes to be centered high in frequency. The performance of the r-f couplers have all been degraded more than expected by either excessive insertion loss or detrimental effects on the r-f interaction in the coupling region. In view of the above results three improvements are required in a new design. These are: (a) higher beam power so that the required interaction efficiency may be lower (b) adjustment of the electrical operating conditions so that the small signal gain is at least as large as the large signal gain, thereby eliminating the inverse overload characteristics (c) adjustment of helix-beam geometry relationships so that the normal band of operation is in the 100 to 300 mc range, rather than the approximate 200 to 600 mc range of the present tubes. 4.3 New Electrical Design, TW-147. The new electrical design assumes a power output of 125 watts at midband to allow a 1 db fall-off of power level at the band edges while giving a minimum of 100 watts at the band edges. Assuming a maximum conversion efficiency of 22.5 percent at midband, the beam will require 550 watts of d-c power. A 0.500ampere 1100-volt electron beam was chosen for the operating parameters for optimum large signal performance. Small signal gain data was therefore calculated at 1000 volts. The physical dimensions and the small

-22signal electrical parameters were calculated for the new design which uses the same electron gun as the TWT-143-A tubes and are listed in Tables 4.2 and 4.3. Table 4.2 Physical and Electrical Parameters of TW-147 V = 1000-(1100 large signal optimum) volts 0 I = 0.500 amp a = 0.472 inch (helix mean radius) b = 0.950 inch (shield radius) TPI = 8 r-f match - coupled helix couplers collector - 1 stage depressed potential gun - 4 electrode lens cancellation presently used in TW-143 JO = 0.84 amp/cm2 BB = 182 (Brillouin magnetic field) B = 350 gauss (expected operating magnetic field) a = 0.55 (beam thickness/beam to helix spacing) Table 4.3 Design Parameters of TW-147 100 mc 200 mc 300 mc ya 0.58 1.29 2.09 C 0.38 0.30 0.21 QC 0.117 0.176 0.341 DLF (assumed) 0.8 0.8 0.8 ka 0.025 0.050 0.075 y(a-ro) 0.252 o.560 0.910

-23The mechanical design of the new TW-147 tube has been completed. Figure 4.7 shows the mechanical design. All tube parts are under construction and cold tests are under way at the present time. The first TW-147 tube will be constructed and tested early during the coming quarter. 5. Summary and Future Work (G. T. Konrad) The P = 20 gun design has been completed as far as the electrical parameters and the geometry are concerned. The mechanical design of this gun will be along similar lines as the P = 4.46 gun. It is expected that the gun will be constructed and tested in the beam analyzer during the coming quarter. The computer work on the smaller diameter P = 20 gun ultimately to be usable in a high power vhf tube will continue during the next quarter. The data obtained on the electrostatically focused tube has been encouraging. A broken lead within the tube prevented complete data from being taken. At the voltages that could be obtained before the tube has to be rebuilt, much improved beam focusing was observed. Early during the next quarter the tube will be rebuilt and testing will be resumed. Several more 100-watt Crestatrons have been constructed and tested during the past quarter. The data indicates that the power levels achieved with the present tube design have been sufficiently high, but that the tubes are centered too high in frequency. This is believed to be due to a nonoptimum design in the r-f structure-electron beam configuration. Thus some design changes have been made in order to overcome these difficulties.

D. C.EEDTHRUS R.F.FEEDTHRU D.~~~~~~~R C. FEEDHDJSP206 WATER HELIX MOUNTING RODS CONNECTION NOTC~HED FOR MAIN HELIX PUMPOUT r TUBULATION 1 ~ ~~~~~~~~~~~~~~~~~~~~~HELIX MOUNTING GU DEPRESSED POTENTIAL ROD RETAINER U COLLECTOR APERATURE COUPLED HELIXOOLE ASTY' COUPLER ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~CEAI COLLE FCV SURFA - - -- - - - -- - - - SNAP RING NLOSSY CERAMIC HELIX CENTERING/ WELD FLANGES RINGS g~CERAMIC FIG. 4.7 CROSS SECTION VIEW OF TW-147-.

At the present time the mechanical design of the modified tube has been completed and cold tests as well as construction of the new tube are underway. It is expected that the new tube will be under test early during the coming quarter.

DISTRIBUTION LIST No. Copies Agency 1 Commanding Officer and Director, U. S. Navy Electronics Laboratory, San Diego 52, California 2 Commander, Aeronautical Systems Division, Wright-Patterson Air Force Base, Ohio, Attn: ASRN 1 Mr. J. Enright, ASENET-1, Electronic Technology Laboratory, Aeronautical Systems Division, Wright-Patterson Air Force Base, Ohio 1 Commanding Officer, Harry Diamond Laboratories, Electron Tube Branch, Washington 25, D. C. 2 Commanding Officer, U. S. Army Electronics Research and Development Laboratory, Electron Devices Division, Fort Monmouth, New Jersey 1 Commander, New York Naval Shipyard, Material Laboratory, Code 924, Naval Base, Brooklyn 1, New York 2 Chief, Bureau of Naval Weapons, Department of the Navy, Washington 25, D. C., Attn: RAAV-4423 1 Chief, Bureau of Ships, Department of the Navy, Washington 25, D. C., Attn: Code 691A4 4 Chief, Bureau of Ships, Department of the Navy, Washington 25, D. C., Attn: Code 335 1 Director, U. S. Naval Research Laboratory, Washington 25, D. C., Attn: Code 5240, Dr. S. T. Smith 1 Director, U. S. Naval Research Laboratory, Washington 25, D. C., Attn: Mr. L. A. Cosby, Code 5437 2 Director, U. S. Naval Research Laboratory, Washington 25, D. C., Attn: Library 2 Advisory Group on Electron Tubes, 346 Broadway, 8th Floor, New York 13, New York 1 Commanding General, Rome Air Development Center, Griffiss Air Force Base, Rome, New York, Attn: Documents Library RCOIL-2 1 Commander, Rome Air Development Center, Griffiss Air Force Base, Rome, New York, Attn: Mr. H. Chiosa, RCLRR-3 10 Commander, Defense Documentation Center, Cameron Station, Alexandria, Virginia

No. Copies Agency 1 Dr. G. Rosselot, Bendix Corporation, Research Laboratories, Northwestern Highway and 10-1/2 Mile Road, Southfield, Michigan 1 Dr. J. G. Meeker, Bendix Corporation, Research Laboratories, Northwestern Highway and 10-1/2 Mile Road, Southfield, Michigan 3 Mr. A. G. Peifer, Bendix Corporation, Research Laboratories, Northwestern Highway and 10-1/2 Mile Road, Southfield, Michigan 1 Bendix Corporation, Systems Division, 3300 Plymouth Road, Ann Arbor, Michigan, Attn: Technical Library 1 Litton Industries, 960 Industrial Road, San Carlos, California, Attn: Technical Library 1 Dr. R. P. Wadhwa, Electron Tube Division, Litton Industries, 960 Industrial Way, San Carlos, California 1 The University of Michigan, Willow Run Laboratories, Ypsilanti, Michigan, Attn: Dr. J. T. Wilson 1 Microwave Associates, Burlington, Massachusetts, Attn: Technical Library 1 Microwave Electronic Tube Company, Inc., Salem, Massachusetts, Attn: Technical Library 1 Radio Corporation of America, Power Tube Division, Harrison, New Jersey 1 Raytheon Company, Burlington, Massachusetts, Attn: Technical Library 1 S-F-D Laboratories, 800 Rahway Avenue, Union, New Jersey, Attn: Technical Library 1 Tucor, Inc., 18 Marshall Street, South Norwalk, Connecticut, Attn: Technical Library 1 Westinghouse Electric Corporation, P. 0. Box 284, Elmira, New York, Attn: Technical Library 1 Bendix Corporation, Red Bank Division, Eatontown, New Jersey, Attn: Dr. James Palmer 2 Scientific and Technical Information Facility Attn: NASA Representative (SAK/DL) P. O. Box 5700 Bethesda, Maryland 20014

DD UNC LASSIFIED~~~~~~~~~~~~~~~~~~D ________UNLSSFE The University of Michigan, Electron Physics Laboratory, Ann Arbor, 1. Introduto The University of Michigsn, Electron Physics Laboratory, Ann Arbor, 1. Introduction Michigan. RESEARCH ANT DEVELOPMENT OF HIGH POWER CRESTATRONS FOR S. ComputerDsg fHg-evac Michigan. RESEARCH AND DEVELOPMENT OF SIGN PGWER CRESTATRGHS FGR S. Computer Design of High-Perveance THE 100-30C MC FREQUENCY RANGE, by G. I. Konrad, C. K. Rhee. Hollow-emGn THE 1G0-3GG MC FREQUENCY RANGE, by G. I. Konrad' C. K. Rhee. Hollow-Seam Guns Jaur,16,2 P nl lu.(otatN.Nbr843.Experimet nteEetottcly January, 196k. 25 PP. tool. illus. (Contrsct No. N~bsr-814G3, 3. Experiments on the Electrostatically- Prjanucy Se9ia, 25. SF10 toolillsk (ContrctNoS29r8105 Focused olwBsilb Project Serial No. SF0100 201, Task No. 9294) Focused Hollow-Seam lube PoetSraN.SFGG21Tsko.94)4. Work Conutda h edxRsac 4. Work conducted at the Bendix Research A series of trajectory plots is shown which led to a reasonably Laboratre A series of trajectory plots is shown which led to a reasonably Laboratories good electrical design for the P 250 gun. The work done on the &mr good electrical design for the P = SO gun. The work done on the 5. Summary and Future Work I. Konrad,.I elecrosatiallyfocsedtubeusig aP,, 4.6 gn inicaes hat I. Konrad, G. I. electrostatically focused tube using a P. = 4.46 gun indicates that II. Rhee,C.K is ~~~~~~~II. Rhee., C. K much better focusing can be obtained with the improved gun. At reduced much better focusing can be obtained with the improved gun. At reduced voltages the beam transmission is only fair but it is shown that the voltages the beam transmission is only fair but it is shown that the percentage of transmission is improving as the design voltage is percentage of transmission is improving as the design voltage is approached. approached. In order to center th operating band of th 100-watt CrestatronsIn order to center the operating band of the 100-watt Crestatrons more nearly within the desired requency range and in order tomore nearly within the desired frequency range and in order to more nearly within the desired frequency ramge and in order toovercome the r-f losses observced in the couplers, a revision is made overcome the r-f losses observed in the couplers, a revision is made in the tube design. The new dimensions and electrical parameters in the tube design. The new dimensions and electrical parameters are shown. are shown. UNCLASSIFIED UCASFN DD ______ UNCLASSIFIED DODNLSSFE The University of Michigan, Electron Physics Laboratory, Ann Arbor, 1. Introduction The University of Michigan, Electron Physics Laboratory, Ann Arbor, 1. Introduto Michigan. RESEARCH ANT DEVELOPMENT OF HIGH POWER CRESTATRONS FOR 2. Computer Design of High-Perveamee Michigan. RESEARCH ANT DEVELOPMENT OF HIGH POWER CRESTATRONS FOR 2. ComputeDsinoHghP-vac THE 100-500 MC FREQUENCY RANGE, by 0. T. Konrad, C. K. Rhee. Hollow-Beam Guns THE 100-500 MC FREQUENCY RANGE, by G. T. Konrad; C. K. Rhee. Hollow-emGn January, 196k, 25 pp. inel. illus. (Contract No. N~bsr-81403, 5. Experiments on the Electrostatically- January, 196k, 25 pp. inc. illus. (Contract Ho. N~bsr-81403, 5. Experimet nteEetottcly Project Serial No. SF0100 201, Task No. 9294) Focused Hollow-Beam Tube Project Serial Ho. SF0100 501, Task No. 9294) FocusedHlo-emTb 4. Work Conducted at the Bendix Research 4. Work Conutda h edxRsac A series of trajectory plots is shown which led to a reasonably Laboratories A series of trajectory plots is shown which led to a reasonably Laboratre good electrical design for the P 20S gun. The work done on the 5. Summary and Future Work good electrical design for the P = 20 gun. The work done on the 5. Sumar adFuur-Wr 4.46 gu indicaes that I. Konrad, 0 T. electrostatically focused tube usn.=44 u niae htI. Konrad,.T electrostatically focused tube using a PTheC.usn = 4.46 gun indicates that II. Rhee, C. K. I Rhe much better focusing can be obtained with the improved gun. At reduced. much better focusing can be obtained with the improved gun. At reduced voltages the beam transmission is only fair but it is shown that the voltages the beam transmission is only fair but it is shown that the percentage of transmission is improving as the design voltage is percentage of transmission is improving as the design voltage is approached, approached. In order to center the operating band of the 100-watt Crestatrons In order to center the operating band of the 100-watt Crestatrons more nearly within the desired frequency range and in order to more nearly within the desired frequency range and in order to overcome the r-f losses obser-ved in the couplers, a revision is made overcome the r-f losses observed in the couplers, a revision is made in the tube design. The new dimensions and electrical parameters in the tube design. The new dimensions and electrical parameters are shown. ~~~~~~~~~~~~~~~~~~~~~~~~~~are shown. UNCLASSIFINTUCLSIFE

DD _______UCASFE DD _______UNCLASSIFIED The University of Michigan, Electron Physics Laboratory, Ann Arbor, 1. Introduto TeUniversity of Michigan, Electron Physics Laboratory, Ann Arbor, 1. Introduction Mihgn EERHADDVLPETO IHPWRCETTOSFR2. Compute eino Ng-evac Michigan. RESEARCH AND DEVELOPMENT OF HIGH POWER CRESTATRONS FOE 2. Computer Design of Nigh-Perveance TEE 100-300 MC FREQUENCY RANGE, by 0. T. Konrad, C. K. Rhee. 5. oEpermetonheEcrsaialy TEE 100-300 MC FREQUENCY RANGE, by 0. T. Konrad, C. K. Rhee. Hollow-Beam Guns January, 1964, 25 PP. inci. illus. (Contract No. NObsr-81403, Focuspedr olwBenTb January, 1964, 25 pp. tool. illus. (Contract No. NObsr-81403, 3. Experiments on the Electrostatically- Project Serial No. SF0100 201, Task No. 9294).ForkConutdatteBnixRsac Project Serial No. SF0100 201, Task No. 9294) Focused Hollow-Beam Tube.WrC 4. Work conducted at the Bendix Research A series of trajectory plots is shown which led to a reasonably Laboratre A series of trajectory plots is shown which led to a reasonably Laboratoriesgodectia sgnfrheP=2gu.Tewkdnente5 Sma good electrical design for the P - SO2 gun. The work done on the 5. Summary and Future Work godeetia ein o h Ogn Tewr oeo h I. Konrad,0.1 electrostatically focused tube using a P' = 4.46 gun indicates that I. Konrad, G. I. electrostatically focused tube using a P, = 4.46 gun indicates that II. Rhee,.K p ~~~~~~~~II. Rhee, C. K much better focusing can be obtained with the improved gun. At reduced much better focusing can be obtained with the improved gun. At reduced voltages the bean transmission is only fair but it is shown that the voltages the beam transmission is only fair but it is shown that the percentage of transmission is improving as the design voltage is percentage of transmission is improving as the design voltage is approached. approached. In order to center the operating band of the 100-watt Crestatrons In order to center the operating band of the 100-watt Crestatrons more nearly within the desired requency range and in order tomore nearly within the desired frequency range and in order to more nearly within the desired frequency range and in order toovercome the r-f losses observed in the couplers, a revision is made overcome the r-f losses observed in the couplers, a revision is made in the tube design. The new dimensions and electrical parameters in the tube design. The new dimensions and electrical parameters are shown. are shown. UNCLASSIFIED UCASFE DD ______ UNCLASSIFIED DOD_______UCASFE The University of Michigan, Electron Physics Laboratory, Ann Arbor, 1. Introduction The University of Michigan, Electron Physics laboratory, Ann Arbor, 1. Introduto Michigan. RESEARCH AND DEVELOPMENT OF HIGH POWER CRESTATRONS FOR S. Computer Design of High-Perveance Michigan. RESEARCH AND DEVELOPMENT OF HIGH POWER CRESTATRONS FOR S. Computel eino Hg-evac TEE 100-300 MC FREQUENCY RANGE, by 0. T. Eonrad, C. K. Rhee. Hollow-Beam Guns THE 100-300 MC FREQUENCY RANGE, by 0. T. Eonrad, C. K. Rhee. Hollow-emGn January, 1964, 25 pp. inc. illus. (Contract Ho. Nobsr-81403, 3. Experiments on the Electrostatically- January, 1964, 25 PP. tool. illus. (Contract No. NObsr-81403, 3. Experimnso'h letottcly Project Serial So. SF0100 201, Task No. 9294) Focused Hollow-Beam Tube Project Serial Ho. SF0100 201, Task Ho. 9294) FocusedHlo-emTb 4. Work Conducted at the Bendix Research 4. Work Codce tte edxRsac A series of trajectory plots is shown which led to a reasonably Laboratories A series of trajectory plots is shown which led to a reasonably Laboratre good electrical design for the P 50 gun. The work done on the 5. Summary and Future Work good electrical design f or theP P - SO gun. The work done on the 5. Summar an uueWr electostatcallyfocusd tub usin a P.46 gn indcatesthat I. Konrad, G. I. electrostatically focused tube using a P- 4.46 gun indicates that I. Eonrad,0.1 elcrsttcll ouedtb uigaPL.6gnidctsta II. Rhee, C. K. II. Rhee,.K much better focusing can be obtained with the improved gun. At reduced much better focusing can be obtained with the improved gun. At reduced voltages the beam transmission is only fair but it is shown that the voltages the beam transmission is only fair but it is shown that the percentage of transmission is improving as the design voltage is percentage of transmission is improving as the design voltage is approached. approached. In order to center the operating band of the 100-watt Crestatrons In order to center the operating band of the 100-watt Crestatrons more nearly within the desired frequency range and in order to more nearly within the desired frequency range and in order to overcome the r-f losses observed in the couplers, a revision is made overcome the r-f losses observed in the couplers, a revision is made in the tube design. The new dimensions and electrical parameters in the tube design. The new dimensions and electrical parameters are shown. are shown. UNCLASSIFIED UCASFE

UNIVERSITY OF MICHIGAN 3 9015 03466 2208