. . 1.1. ...... , . il , • . . . i on I OFI ORNL P 2613 . !.. ow wa EEEFEFFE 'n 2. MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF STANDARDS – 1963 * .. ..F LOANL apo 2017 - · NOV 2 9.1966 : ac. 91:20; PN 50 A CRYOGENICALLY COOLED, SCANNING ENERGY SPECTROMMER * J. S. Culver . CONF-661016-21 Oak Ridge National Laboratory Oak Ridge, Tennessee RELEASED FOR ANNOUNCEMENT IN NUCLEAR SCIENCE ABSTRACTS. MASTER ABSTRACT . . A new cryogenically cooled, scanning energy spectrometer . has been constructed for DCX-2. The solid-state preamplifier is built into the scanning head and operates in the same conditions - "*of pressure and magnetic field as the plasma being studied. Cool- ing the silicon-barrier detector and preamplifier improved the resolution for 40 kev protons from 13 kev (F.W.H.M.) to 4.5 kev at 1180 K. . * An interesting feature of the DCX-2•plasma which was discovered with the earlier scanning energy spectrometer is the "central peak" portion of the trapped plasma. Since the beam is injected into a helical orbit, the trapped protons would be expected to retain their axial velocity component as they spiral back and forth between the mirrors. Such spiraling particles are indeed - observed; however, when a high-density plasma is obteined, a large portion of the trapped particles have litile or no axial velocity and appear to remain in a shallow dip in the nominally uniform magnetic field in the center of the nachine. In normal operation, he ions are injected at 540 kev and broken up on either the background gas or a hydrogen arc,producing trapped protons at 270 kev. These particles are observed as expected at a pitch angle of *5 degrees representing both those resulting from dissociation of the injected bean and charge exchange loss of the trapped plasma. The central peak plasma is characterized by partici.es with an energy spread from a few kev to 2-3 Mev. Just how some of the trapped protons reach energies far in excess of injection energy is not understood at this time but the answer is thought to lie in the *Research sponsored by the U. S. Atomic Energy Commission under contract. with the Union Carbide Corporation. STEREO - M AI • • • • • • • • • tây " "" : * * * * * * * * * * * * * * * * - - 1 15: 49, I - 1 11 1 1 : 1 HA. TET, ALB:: T H . .. tu . ) ir? ! 4 .1 . - 7. - . . · behavior of the low energy, particles. Due to the mechanical limitations of the machine and the high stray magnetic field, it has been necessary, In the past, to build energy spectro- meters with long coaxial leads between the silicon-barrier detector and the input of a magnetically shielded vacuum tube preamplifier. The resulting high preamplifier input capacity has produced such a noisy signal that it has been necessary to reject all counts below 70-90 key as meaningless. Since it was though that the central peak plasma contained many low- energy particles as well as those observed, it was clear that we must have a low noise system that retained all the capabilities of the old equipment plus the ability to observe particles in the 10 kev range as well. Work done earlier by Bamett and Ray pointed out the virtues of a cryogenically-cooled system, as well as some of the problems encountered; Rowever, since this seemed to 'se the most likely approach at the time, design was started. Since our device must scan "hrough # 45° to observe pitch angle and radial distribution, available solid-state preamplifiers could not be used due to physical size, so a special compact preamplifier and silicon- Barrier detector assembly was developed and constructed by ORTEC for our use. Tests showed the field-effect transistor in this preamplifier to be 'virtually unaffected at our field (12 kg) and all component materials were chosen to be compatible with the high-vacuum ambient in which it must it must operate. - To reduce microphonic noise resulting from the boiling liquid N2, it was decided to rely on radiation cooling which also eliminates the need for a flexible coolant line in vacuum. The entire scanning assembly (Fig. 2) is enclosed in a cooled copper box, thereby eliminating, as far as possible, Cert any direct contact between preamplifier and boiling liquid N2. Tests with thermocouples on both box and preamplifier showed this system capable of cooling the critical parts to the optimum temperature of N 1250k with power on in about 15 minutes. The components of the collimator-attenuator and detector system are : shown in Fig. 3. The slit assembly is set at 20 micron width and the stick contains 10, 20, and 40 micron pinhole apertures. This gives an adequate range of attenuatior to permit experiments under a wide range of counting rates. The 50 mm2 silicon-barrier detector is unmounted and has a depletion depth of 1000 microns. The front end of tire entire assembl.y can be seen in Fig. 4.. Calibration of the completed assembly was obtained in the facility of Barnett and Ray which produces monoenergetic protons. To simulate operating conditions as nearly as possible, the 150-ft. cable (later installed on the machine) was included in the circuit. Performance at room temperature and at -150° C is shown in Fig. 5. Although it was not intended to operate this system at room temperature, its performance at 20° C 18 substantially better than our previous devices. The curve in Fig. 6 Illustrates a broad temperature range over which one can obtain near maximum resolution. The family of curves in Fig. 7 show a nearly constant resolution down to 20 kev when observed at optimum temperature. All of these curves were traced directly from data read out of the multichannel analyzer on a point piotter. The group of spectra in Fig. 8 illustrates typical energy data which can with background gas breakup (principally Aż at 2 x 10-7 torr). During this 11 1 .: . .... ........ . - * - . * * . . * . * . - - * run the att beam was pulsed ou for two seconds and off for two seconds to allow the plasma, to decay. : Spectrum (a) 18 typical of a scan from 45° cast to 45° west in about : 3 minutes. This spectrum includes all particles with pitch engles between these limits including those in the central peak. The prominent peak at 270 Key 18 due to dissociation neutrals from the bcam as well as charge exchange neutrals from the trapped protons resulting directly from beim breakup. The 180-kev peak is a group of neutrals resulting from the dissociation of small amounts of Hy which 18 unavoidably injected with the beam. The :: higher peaks represent coincidence counts. These are the result of the inability of the analyzer to separate two or more particles that arrive within 1-2 microseconds thereby giving a peak representing their combined energies. These series of peaks are convenient in making ar. energy calibration ca. 28 well as defining the properties of the plasma. Spectrum (b) represents a typical distribution when looking at the "side lobes", or the pitch angle of the injected bean only. Since spectrum (a) included these side lobes, the two are naturally similar except for the low-ef.ergy end. The count rate at the low end is actually falling as might be expected of an energy distribus tion resulting principally from the 270-kev particles. Spectrum (c) represents' the central peak only and is completely devoid of any of the peaks scen in (a) and (b). This is where most of the low-energy and high-energy particles are found. Since this diagnostic tool is quite new to the machine, the full significance of its use cannot be known at this time; however, it has already produced the answer to the previcusly unanswered question: "Are the low.energy particles really there and do they represent a significant fraction of the total plasma?" kl . " - - REFERENCES . 1. 'J. 8. Culver, "DCX-2 Scanning Energy Spectrometer", Proceeding of 1965 Symposium on Engineering Problems of Controlled Thermonuclear Research, May 4-7, 1965, Lawrence Radiation Laboratory, Livermore, Calif., CONF-650512, p. 123. C. F. Barnett and J. A. Ray, Thermonuclear Div. Semlann. Prog. Rept. April 30, 1965, ORNL-3836, p: 67. LEGAL NOTICE This report moorepared a BA Account of Tovenaeal Momord work. Neither We l'ailed SWO, MOJ Uhe Coavaluston, nor any person ACUR on behalf of the Comminlani W. Makes any warranty or represallon, expressed or implied, with respect to the lacu- racy, completeness, or wachaint of the laborator caland A do moport, or that we we of Lay lafortuition, apparts, wethod, or process discloud la We repos may not Infring frinnly owned rightoj or B. Aamo way Ilabilities with respect to the use of, or lor dangen remur from the UM any inforaation, apparatus, method, or proctv diesloond in the report. As und la the bone, "persoa dollag oa behalf of the Countuloa" includes may t- plore or coalnictor of the COADIHoa, or soplore of such contractor, to the extent that soch employee or coatractor the Commission, or employee of moich contrrstor preparne, disnaintes, or provides accuW to, any aforostloa pureuat to Me employant or contre, with the Commission, or his omploymeal with such contractor. ****...... 11 PREAMPLIFIER ; 1 . . . t . . WCY . CABLE DRIVER Fig. YO. . . 17 1 . . * * Asian . Li . . . E. ALL . 04 TA 29 . Liridon writime T . . "i ? 1 in time since . : : . :................. A 4 . - 4 "HTML . .HNE . -.'-.-. ... . . . AN --.- .. . . r .. .. M4 .. . .. , PRAKA . . . . 1 Fig.? . . . 17 . .. .- PANA . . St. HOM . . . . - - . " - - . . . . .. . . . THM - JAY - - . . .. . . DA R T . . . । . . . N प . . . . . i i .. . . Ty iinand weiter 1 1 N2 * V ? .. Fig. 3 . . . CA .- PUR Fr . R . FL ..- . -.. . . . . SIN . VWXMV . . . . .- : 5. N44 . ... VA - . S . . VY . SV . . . . 17 I ** . . ! SU * V OR 2 . 2: . AL " " • . ? . 31 1 . . w t . .. . : . 11 1 . A p E. NL r k . s 1.TEMAS . . ** C - 4 . * . - . 1". . . .. . .... .. . . ..... .- 1.1 -... - - - . . . ." ..." ... ..... .. - "Niti - | i- Prii:: : :: . 1 -- 了 ​, - - = --Fi * 一對 ​WAN! 1 中華 ​春时​”, : 14 青 ​全名​: しかしだっ ​4 , 丁 ​, 这三是 ​- 鲁 ​= 一 ​: ,是 ​5, 考 ​字 ​一個是書本 ​本 ​. m 書本一一一一一一​”, 一直對 ​+T 一串​! - rit, . 一一一一​= 安 ​對了​, .. TITE - - - 4 . -星事看 ​1 ' 一學单​,一 ​' 1 . = 产二科特​, 量 ​。 中的一 ​*本外 ​= - - 一 ​4, . , 得​, 是 ​量 ​- 者​, - 新手上 ​「 . * 一十一 ​等等​, 种事情​,, 非常非一無 ​年4 ir","p4 --量 ​11 . - -- - : : . ” ; - 工作​, le - , 特马 ​. - , 中华料 ​的性能​。 : 4 N 中学 ​一件事 ​大 ​。 - _ 的成 ​EL 事 ​RE 重量​: - 4, 許 ​* 其實 ​7. 上 ​将 ​, 14: * - 了中 ​* 1, iTV - : , 上平台 ​的事​, 市中正 ​L1 - 幕會 ​- 1 7 HAMM ite 只是 ​一對 ​只 ​- 另 ​「事 ​- - 」 了​。 。 F1 - - 专科學 ​” 44 * - - 工事 ​- 「是是 ​, 等 ​- - * 事 ​4- * 。 - (中一 ​- - - es"事事 ​青青 ​中​, - 曲 ​: t # 其中一本 ​# 查​, - , -- 一 ​华 ​lis www...... 1* E USB . 一 ​? TV ** .. . - 5. 1 , 6 馬 ​1 在上 ​: , 。 有 ​年 ​- 1 “ : : 無 ​--- . 和 ​#ifi SNS ." 4 .. 「 . , . - , 一上一 ​th 学者 ​4 - 14 41 - . 更牛 ​, 工作 ​- 1" 重生​, its, , 关 ​. 1. , #fit 學畢 ​看看 ​, 资 ​, 鲁 ​上了 ​的心始终 ​. . “**, 中 ​44, d ,14, . - 1 电 ​! 中青年 ​作平川​, . 1. : # .4" 在 ​學中​,有 ​1 中 ​h 走马4年 ​是​。 , 「 南非​- 4 : 在建产 ​-14mm -- - - 一个 ​为争当事 ​年 ​, eir t 中 ​, 在中中1 4 - 早年事业单 ​必吃 ​- SS : , . : 片长学MP4 1. 性 ​: r 但是​, 事事 ​十五世其昌 ​A 4 4 本土青 ​* , 本社 ​. 在 ​- . 司 ​- 我 ​- “ 善华事 ​*本產​, - 鲁 ​一事​, 4 “ 基 ​。 一条​: - , - - 学生的 ​事 ​上 ​其他​: 事件​:多 ​寸​:33. * 由 ​th, ･ , _ 中 ​: , 第44-14 ” ケット ​重量 ​岁 ​我也 ​本身​, 重 ​林中学 ​. - 出事​」 . : - 工作 ​作者 ​- 不 ​“… , -- * # , - 41 一看​, +1 事事​, 学学 ​- LE, 事 ​. 事​, lr. - 作中 ​**41 业务​。 者 ​( ”重 ​事 ​4 . 中国一重 ​, - . . 。 “ 中 ​.. " 」 立 ​E身 ​- 。 *.* 年三事 ​1 , 导 ​1611 int ,事事 ​- 和生 ​. - - - 444 . 4 al . . “ 的事​, .Y 本作中​, : * 4春 ​- - : . 于 ​· 中 ​学本科 ​产 ​.. 1 . 1 本书​, 一个是半年 ​了市 ​**。 十 ​. 中 ​, --- 、 . 1.事 ​中 ​" - . f * , - - , LP 基本 ​- 事业单 ​” 于 ​。 臺 ​都是一 ​李 ​“ , 一 ​一是 ​一 ​业单 ​。 · !* . . 中 ​小学生 ​「 1 - こですか ​是​, - 重 ​」 r 作 ​, , ; - . 1 华中学 ​T " 中 ​上 ​/ 了一會 ​11 日本FF 44 售中 ​.. M.1414-14 -- 141 件 ​导体 ​式中​: 4 “ , 11: 1 」 11 4 本的 ​. 中 ​- - * 非事先 ​. * . 41 - 人生路程​。 F1-FI, 其中​, 山上​, . hi . “ 举重 ​治法​: - - 1 - 2 4 量 ​_ ·一本​, * . - - 1 . /* 基本是 ​中 ​老 ​基 ​一是 ​4 # . . 王者事 ​.. MAMA . : 「 . . 中式 ​ . ... . . ... . .. .-.- Y.- t ni c .... .. . . 7-" U r i " : "", "W ". . .. ... .. ..... . -MT TITULYA intr w U to b e more - : : .. . is . . 40 kev 12.3 kev 30 kev evet 13.6 kex : Arbe Fig. 5 . 20°C :EFFECT OF TEMPERATURE ON RESOLUTION -'150°C ..: ' . 40 key sev key u RESOLUTION kev . . 140. 100 120 TEMPOK Fig. 6 . 1ER . * ' ' t ; E TER * . < 20 kev TEMP, 118 K -30 kev TEMP. 118ķ -40 kev TEMP. 118 K kev 4.4 kev 4.6 kev - * T. . IT: ...:: :. RESOLUTION OF A MONO-ENERGETIC PROTON BEAM . . . . Fig. 7 - - - .* . 3 .. T : 2 1 CUCU 4W FAN . . 1 . . 1 E 2 + - . . 12 EL 1 . - . N NONNA T41 . . DK 2 11. LT-9 . YRA XI. CL . TL 2 - NA ILL UN . 4 1 . XXX . INN - . " RI . V . . TV .- PC TV . " . ' SR . . IN .! . + . 1 ANT T - * + MS. . Ni .- SIX * T .1 . TUA PYTA. AJ biti OS 1: 5! LA 2. OCE . . . HE . i 71 I 2 . . 17 . ME in . - 10 . 12V . - LIBER . 95" S 2k . 21.1 . 22 el. CH SU 2. Ow M . 2X . . 3. . . . . . . EPI .it . t 1 2 . *.. CS . * Ba't" MI . . 1 - I 10 11. ! . . . . N SM I . 1 0 . 34 * . s. . . re . . 00:15 . . . . 14 10 | . . 09. . os . . ., W . Pi IN * 14 . . A :IN . TO * * i. . . 1 FULL SCAN 11 . . LO * * . 4 BA . . LE 7 R . . 1 . IN li TH NI ' . 2 1 * . . + AL VA CN . A " * . ** 7 :. 1 . 1. 1929 . . US NO . w G . * w ii . .. .. . .. . . 1 II.S Litir AS . tuliwa XY YO 1 .. T . - . I . . N . . . OD . . 10 " 0 IN - CZ . 1 11 1,2,3 Ar LI . *** . . N. SN * . . TO KI . WR IT * . ** . HIT 1 ET PI X2 KEYTOKEA . . ON . w TEL . N . D * * T $ . . . . * ry . . . . 11. TE ITI . . M 11tb . . . 2 HY: . . list will - . . "UTTA . 2 ? TIL * PT LI 5 N ST . ,. CC WERKEN 1,5L IN UV NA . VEL : z DAH OS 2 . . R. . w 1 1. 11, IN RY M . .. . . . w EESTI REN PO INT vy S . TON TIN . 1 . . L in! . . OTS . . . I . O ' GA M . 11 SI : - T . . . i PKY.SI * * . re + 2 . * .. . . 2 1 er II. . " . 1 MI.. X : j " . 1 V 1 ISTII i * : . 11 . . . 4 RON . 49 . - . N .. * " V70 ! 01 . . * 1 . ! . . 7. VIRTU i . . . . 2 ' . 11 . V . . ! ! . 10 . ASI 7bt11 1 I 1 . . . . . A . * 1 . . . . 2014 * . * ** 1 ! 2. . ! . . 4 . " . . . . . . . S . S49 . 4 1 .. . tit. 1 OVI : . . . . . ... . A TIT IR R . . . . *** *** . . . . PO 111 4 X TO . . . PE I- Ir II. + ' .. . . ! Ort . . ! INI+ . ! " * . + ? AHL Xi C : 4 4:11: 11 10. . . 1 It .. . . : ** . $ ON II. 1 . ! .61 . . . - . . . . It . . . . 1 . DU . . # . IN- . . . ! . . N ANN . - PK P *.* . * . . . . . . . TL+- PUL . . - . .. E 11.12 . . It! TO . . . .. FULL . . . + . . 11 . . . . . . - A 1: - . 1 . is 1 . . N * . " - . AU A TIL . . . . . . . ..- . . . TES 1 PM . . . . .. . . i . T . . . DA + L X . D . : . LITTLE . . V } - . ES . . + . . O 11_ . (b) SIDE LOBES AT 50 A * Tutut. Brache 11 .. it . . . 11. WH At 11 . . LA 1 VI .: . . L 17 MY . . . . 4 2 .. 1 1 2 * PI * + * . 6 . TIL 11. 1 mas 4 . . . A4 AC . OW KOVO .. . r $ . . Ah . L . * 2. 1 Sit . i hi ! ! AT 11 AVA . 1 . O , . Hele? .* . . . . . . . S . . .. YU . 1 11 . i . . M * t . 3 . # . IN . . . . . . IR. . • 1 TEEN 1 .. . 11.07 otection .'' 4 OS . 1 H KO " O "1 . . 17! . ya : + 2 . . . . . NI . . 1 . . THE TO I O 1 . " + . . . .. . . 10 IV. + ISO TO . . . . re * . 1 . . . . 1 . *.? CHI 1 . . *** . * " . 4 IP: 2 IPS 1 . . * . . 10. L 3 1 . PA . . .. .0 .. 1. . 2 . . . RU Bil . " . . . . .. . 14 . . . . . - : TO . es LI . .. 0 . - . . 2 . POVP OTUN 9 . ' . . ht 2 NE 1. n NI 07 4 1:11 . T 11. . Di TI A ' . 4 .PT + 1 Liu * 1 S nu P . . ESTO 17 TRE . . . Tin 111 . . WIN . NO . TER M LLC INT 0 2 XN2 YS. TO 1 . - . * LW kt 214 1. ' 2 . . OVI . ie ! . r + 10. . . . 1 1 . - ++ + ent ri - . Ich! . A H * . . . 4. TU.. 1: 11. 2 im . WWW . . 19 . . . - AN . .. . - ! . . . 1 . . 2 , 2 . N . . . . . : . at .. 1' + 1 . TIL 11 . ? 6 F . * * . . . . . . . . .. - COM M . . . . . . 1 VN ... . 1 C . . . .. 1 ON P * . . . no . . 1 * A - ti * 7 A . CO XI . US 21 NE . . . . . . T . . . 2. ITE . . . GO SEX . . IN .. . . . NF ! - + T. . . 7 1024 . . O . * . H.MN . R MON M OX IN ... 1 HD * * 11. - 1 .10 . + U . . . . . . . . . * . . 1 ! 1 ..1 . . 1 II -103 - . W # . . . 1 . I. 10 1 . 1 SLA V . . . ! . 2. 14 . 0 I . . el W H D . * i CENTRAL PEAK · AT 00 . . ! 22 . . O * . * T 41 1 . el . . . . :, . ' . DIN- . ' 1 07. . ..in . . 2 1 2 N #1 .. .. . . . • . . . . . 4 . 11 ! ! . . MIT . 16 . . . 1 . + . 101N . . . . " R. . . . . . . . . . 11 . i -. . I ON . . . . . BTT . . ? t . 2 . . 1 . . * 1 . . I . . . MINUL . . . . WO .... .. . . . . VI. Y' ** I . A . . 1 . . 2 :.. 1. 1 . .- . . . . .. . . . . . . . 11 . 7 . . T . . . . . ! SU 1. i . IS . 4 DR. * To 2 . r . . . SO . . .. . * - TO ' 1 . . . al . - 8 . - 19 - - 1 . 3 0 100 200 300 400 500 600 Key : Fig. 8 . . . ......... • .. • • ........ • • ... • • • ........ • • • • • • • • • • • • • • • • • END DATE FILMED 12/ 21 / 66 3 . . . . : 14 . .. ...it LET' ir 1. - ' ri y . . # 2 . 1.4 C !! 1 T ! 5 . TVA 23