CA2089643A1 - Particle accelerator transmission window configurations, cooling and materials processing - Google Patents

Abstract

2089643 9203839 PCTABS00011 A transmission window (14) for a particle accelerator (10) is formed of a thin foil (14) having a predetermined thickness and having a predetermined length, and when laid flat as a sheet having a transverse dimension. The window is formed to have a locus of a curve in cross-section along the transverse dimension such that a radius of curvature of at least a portion of the curve in cross-section is less than the length of the transverse dimension.
Longitudinal channel and tubular shapes are preferred. Window cooling by gaseous and liquid fluid flows is also described. A
transmission window assembly and a particle beam accelerator are also described. As one example, a liquid material processor and processing method employs either the curved window or a conventional window and advantageously directs liquid material onto the window to cool it, while a particle beam passing through the window enters the liquid material and changes it chemically in a predetermined manner. A mobile transporter enabling relocation of the liquid material processor between process sites is also described.

Description

wo 92/03839 2 0 ~ 9 6 4 3 Pcr/uss1/oss4s . :

PAR~C~E ACOE.~-~RAl~R T~ANSMISSION WINDOW
CONFIGIJRATIONS, COOLING ANI~ MATERIALS PROCESSING

The present application is a continua~ion-in-part of U.S. Patent Application Serial No.
07/569,092 filed on August 17, 1990, entitled "Transmission Window for Particle Accelerator", now abandor~ed. The prcsent application is also related to,a commonly assigned, copending U.S. Patent Application Serial No. 07/569,329, also filed on August 17, 1990, and entided "Particle Bcam Generator", now U.S. Pa~cnt No. , the disclosure of which is inco~ated h~cin by rçfeTence.
Field Qf th~ Inven~on The present invention rela~es to high encrgy par~clc accelerators especially for use - within industrial processes for ~eating various materials. More paricularly, the present invention relates tO an improvcd transnLission window for a particle accslera;or and improved cooling med~o~s and apparatus for drawing heat away ~rom the ~nsrnission window.
Baçk~ound ~f ~he Invention Particle accelerators are employed to irradiate a wide variety of materials ~r several purposes. One purpose is to facilitate or aid molecular crosslinking or polymeriza~on of plastic and/or resin materials. Other uses include sterilization of foodstuffs and medical supplies and sewage. and the des~uction of toxic or pollulting organic materials from water, sediments and soil.

~ A particle beam accelerator typically includes ~i) an emitter for emimng the panicle beam, (ii) an accelerator for shaping the emitted particles into a beam and ~or directing and - accelerating the highly energized particle beam toward a tTansmission window, (iii) usually a beam scanning or deflection means and (iv) a ~ansmission window and w~ndow mounting. A
generator is provided for generating ~he considerable voltage difference needed to power the accelerator. -a;: ~ The ernitter and the accclerator section, which mày comprise centrally arranged dynode elements or other beam shaping means, or eleclrostatic or electromagnetic ienses for shaping, focusing and direcing the beam, are included wi~hin a highly evacuatéd vacuum chamber from 35 which aL molecules have been removed so that they cannot interfëre with the particle beam during the ernitting, shaping, directing and acceleraling proccsses.

, . , , . . . ~ .
,, "
.
.
, ~' :' ., :' . ., . :

WO 92/03839 P~r/US91/058~5 20g9~a~3 ;'-' The ter n "parsicle accelerator" includcs accelerators ~or charged particlcs including7 for exarnple, electrons and heavier atorr~c par~cles, such as mesons or protons or other ions.
These pa~ticles may be neutralized subsequent to accele~ation, usually prior to exiting the vacuum chamber.
The transmission window is provided a~ a earget end of the vacuum chamber and enables the beam to pass thcreehrough and thereby exit the vacuum charnbcr. The workpiece tO
be ilIadiated by the particle beam is usually positioned outside the accelcrator vacuum chamber and adjacent to the transmission window in the path of the particlc bearn.
As used herein, ''Iransmission window" is a shee~ of material which is substantially transparent to the particle beam irnping~ng thereon and passing therethrough. The transmission window is mounted on a window mounting comprising a support frame which includessecuring and retention means which define a window envelope.
The conven~onal beam transrnission window, usually rectangular wi~h fillesed corners and generally perpendicular with respect to a longitudinal axis of the particle bearn, must be sufficiently thin and of a suitable material so as not to altenuate ~he bearn unduly from energy absorption and consequent heating. The window material must be sufficiently strong to 20 withstand the combined stresses due to the pressure difference from typical ambient atmospheric pressure on one side thereof and high vacuum on the other and due tO the heat generated by the particle beam in passing therethrcugh.

Conventionally, ~ansmission window foils have typically been inst~lled between 25 rectangular, generally flat flanges with filleted co~ners The thin windsw foils are typically formed of itanium or titanium alloy sheets or foils which typically range in thickness between about 0.0005 inches (0.013mm) and 0.004 inches (0.104mm).

When vacuum is d~awn on one side of a conventionally installed, flat foil window, the 30 arnbient air pressure on the other side ~ends to deform or "pillow" the foil window slightly.
Part of this defonnation results from ~ansverse stretching of the foil. The radius of curvature ` of the foi] resulting from drawing a vacuum is defined by the amount of ~ansverse stress incurred. The relation therebetween for a foil of indefinite length ~hat is, neglecting cnd effects) ls given by ~he following~

sl = p(R/t) transverse stress (Ibfim2) Where p = differential pressure across foil (Iblin2) R = radius of curvature (inches) .
,:
.

" .

2 0 8 9 6 4 3 PCr/Usg1/05~5 ,~, , t = thic1cness of foil (inches); and s2= sl/2 a~cial stress (Ibs/in2) and the total s~ess S at any position on ~he window is given by:
S = (sl2 ~ s22) ( given in Ibsrm2).

Bccause the window is not of indefinite length, the ends thereof are subJe~ted to addilional aldal seress as well as transverse stress because of the transverse and, end reten~on structure adjacent thereto. The combination of axial and transverse stresses often results in vrinkling, non-uniform dcfonnation, or even actual creasing at thc window ends, and 10 increases the chances of preman~ failure the~eat.

Because the sheet or foil ma~enals used for conventional window configurations have inherent strength lirnitations, particle accelerator power output is lilIuted, not by the high voltage generator capa~ty, but by tlle maximum hea~ing due to the particle flux that Ithe 15 window material can withstand. The prior art has thercfore sought to minimize the inc~ease in temperature of the window during accelerator operation or decrease the mechanical stress it is subjected to. One known technique includes, i~or example, providing support gnds inside the accelerator chamber and abutting against the window. In ~his par~icular tcchnique, the suppor grids are often cooled by coolant flowing through intemal cooling passages. While this 20 technique effec~ively increases the active window area, the grids us~d in these known designs are wilhin the beam pa~ and there~ore undesirably absor~ a significant f~action of the incident accelcrated particles. By "active window area" is tneant that area of the window within and def~ned by the securing strocture and having an active transverse dimension. A related technique of increasing the window area without providing additional SUppOIl increases the 25 tendency of the wtndow ~oil ~o fail under stress. Thus, a hitherto unsatisfied need has arisen for an improved ~ansmission window design wherein a given thickness of window ~oil can withstand a much higher particle flux than that contemplatéd heretoft3re.

The efficacy of radiadon-thermal cracking (RTC) and viscosity'reduction of light and 30 heavy petroleum stock, for example, has been reported ir~ the prior art.' Also, high energy ' ;. ~ .. ~ .. ~particle expenments have been conducted in connection witb processlng 'of aqueous ;material including potable water, effluents''and waste products'in order to réduce chemicallv or eliminate ~ toxic organic materials; such as PCBs',' 'dioxi~s, 'phénois, benzenes c ~ trichloroethylene, te~achloroethylene, aromatic compounds,'etc. ` ' ~ ' The techniques heretofore employed have typicàliy presènted 'a liquid sheet or "waterfall" in front of, but spaced away from, the particle beam. 'Conventional wisdom associaled wi~h these lechniques has been to employ very highly energetic particle beam -, :: , . . .
,: . ;.......... ,, : -, .. : . :- . . .
:., ,, , : : :
: . . .. . :
.: -. ,.
: . , . : ; : , ~ - . . . . .

WO 92/n3s39 PCr/US91/058~.5 2089~43 f~

sources (e.g. 1-3 MeV) in order to obtain sufficient particle pcnetration. In order to process useful]y large quantities, high bearn cu~ents, such as 50 rnilliamperes or more have also been proposed. High energy and high 'oearn currents rPquire very expensive voltage generaDon and beam formtng apparatus. Also, the use of a th~n sheet of liquid material being ~adiated has S not been simultaneously cmployed to transfer heat away from a curved transmission window of the bearn. HeretofMe, theTe has been an unsolved need f~r a lower pamcle energy, higher beam cuuren~, higher efficiency irradiation apparatus for radiation processing of materials such as petroleum stock, potable watcr, effluents and othcr aqucous and liquid rnateAals.

.
Summary of the Invention A general object of the present invention is to provide a novel transmission window design whereby the window foil is subjected tO lowcr transverse stress, lower axial stress and Iower total stress whcn subjected tO a pressure difference bctween the tWO faces thereof, which is more ~adily and effectively cooled, and which still enables substantially all, e.g. at 15 least 90% or even at leas~ 95%, of the accelerated incident particles tO pass therethrough in a rnanner which overcomes tne limitations and drawbacks of the prior art.

One more specific object of the present invention is to provide an improved ~ansmission window configuration ~or a par~cle accelerator in which overall s~ress for a given 20 particle flux is considerably reduced over that rnanifested using a substantially fla~ window of equivalent active area.

The teT~n "overall stress" means the combined stress due to the pressure difference across the w,ndow 'oetween atmospheric pressure on one side thereof and high vacuum on the 25 othèr as well as due to the increase in temperature caused by the energy given up by a given particle flux in traversing the window which temperamre increase results in a decrease in ~he ability of the window mate~ial to resist mechanical sr.~ss. P.y "substantially flal" we mean that the window in the absence of any pressure difference thereacross has a radius of curvature which is relatively large, for example, 100 times the ac~ive transverse dimension thereof.
30 Thus, the radius of curvature of such flat windows is essentially infinite in the absence of any curvature resulting from the application of a pressure differential across ~he thic~cnèss~thereof ` when the window is first mounted in the accele~a~or. Of course, once a vacuum is drawn on ~ .
one side of the windnw when mounted in the accelerator hsusing, the nominally flas window ~~ -will tend to yield both elastically and to some degree pemlaJlently. For ~itanium windows the 35 deforrnatjon is largely elastic, and these foils substantially recover from such deformation when the deforming stress is removed. Aluminum windows used in the prior art often undergo some amount of pe~nanent deformation after initial application of a pressure differénce thereacross and exhibit some degree of "dishing" thereafter.

wo 92/03839 ~ ~ ~ 9 6 ~ 3 - Pc~/ussl/os84s : . , Another objecl of ~he present invention is to pro~ide a transmission ~qndow which reduces Iransverse stress by providing an active area following a curled contour in transverse cToss-section such that a ~dius of curvature thereof is less ~han twice the Iength of ~he active 5 transverse dimension.

Ye~ another objeet of ~he present invention is to provide methods and ap~aratus for the radiation processing of materials earried in fluid mediums while a~ the same time advantageously using the fluid medium for the effieient eooling and condue~ng of heat away 10 from a transm~s~lon window of a high power, low cnergy panicle accelerator. Ttli5 method of using the process rnaterials and fhlid medium for eooling the window also achieves the desired result of raising the temperature of the materials in a eontrolled ~ashion as ;nay be conducive to desired chemical reacdons. lBy placing the materials to be processed into direct proximity of the beam window for cooling it also advantageously increases the incidence of energetic 15 pamcles and electrons in the matcnal, leading to a desired process result at lower beam energies, and ~herefo~e lower cost and complexity, dlan heretofore achieved.

A further object of the present invention is to provide a transmission window which r,nay be cooled more ef~icicntly with a cooling fluid stream, thereby increasing the capacity of 20 the window to ~issipate higher power levels for a given window foil thickness.
, Yet another object of the present invention is to provide an improved and more efficient cooling arrangemçnt and method for conducting heat away from a transmission window of a high energy particle accelerator, thereby increasing the capacity of the window to 25 dissipate higher power levels for a given window foil thickness.

ln accordance with pnnciples of the present invention a transmission window for a particle accelerator is formed from a thin foil having a predetermined thickness and having a predetermined length between a first end and a second end, and a width, when laid ~lat as a 30 sheet prior to forming. Ihe window along at least par~ of its length comprising an active area is forrned to have the l~cus of a curve in cross section along an active tr,ansverse dimension such that a radius of curvature R of at least a portion of the curve in cross section is less than n~ice the lenrth of the active t~ansverse dimension. ~ ;

. ;In one presen~ly prefe~ed specific embo~diment of the present invëntion, a particle beam accelerator includes a housing defining a vacuum chamber, a charged particle source for ~enerating a particle beam within the vacuum chamber and a particle accelerator for accelerating and directing t,he parLicle beam toward a first end of the housing which has been - ~ , .:

:, . .

~ .
.

wo 92/3238 ~ 9 6 4 3 PC~/USg1/05845 adapted to allow accelerated par~cles to pass ~hcrethrough. The housing includes an upper flange at the first end and a remoYable lower flange which mounts against the upper flange.
The terrns "upper flange" and "lower flange" as used in this specification are to be understood and interpreted in rela~on to the panicle beam direction, thc upper flange being closer tO the S particle source than the lower flange. The upper flange and the lowe~ ~lange together include a secunng mechanism to secure the window foil which is mounted thercbetween and defines aligned openings tO the interior of the chamber which have a length ~nd an act~ve transverse dimension. The aligned openings may or may not be coextensive. The uppcr flange and the lower flange further define a eurved locus at each of said first and sccond cnds along the 10 ~ansverse dimension. A ~ransTn~ssion window is formed of foil sheet material of a size sufficient to cover the aligned interior openings of che upper and loweT flanges and the securing mechanism, and being of predetermined thickness. The ~ansmission window is removably mountable betwcen the upper flange and the lower flange such that the curved locus at each end along the activc ~ansverse dimension forms the transmission window into a 15 cu~ved channel configuration having a finite ~adius of cu~vature in cross sechon along at leasl a portion of the transverse direction, Ihe portion preferably being substantially the whole length of the acive ~nsverse dimension, but not greater.

In one aspect of the above described embodiment, the par~cle beam accelerator further 20 comprises a sealing gasket`disposed belween the transmissiun window and the upper flange and functioning as a sealing mechanism therefor.
, : . . i , .
In another presently preferred embodirnent of the present invention, the curved transrnission window may be formed tO define a cylindrical tube through which a saand is 2~ drawn for radiation processing by the particle beam.

In another aspect of the invention the active area of the ~ansrnission window prior ~o being mounted between~ the upper and the Inwer flanges of the accelerator housing is not substantially planar. Preferably, the ~ansmission window of this aspect of the invention is 30 preshaped to present a convex surface of generally elliptical shape to d e vacuum chamber.

In yet another aspect this invention provides a particle beam accelerator including a housing defiming a vacuum chamber. A par~cle beam gcnerator for generating a particlé beam is within the vacuum chamber, as is a beam directing s~ucture for directing Ihe particle beam 35 toward a radiation emission end of the housing; The housing includes an upper nange at the em~ssion end and a removable lower flange. The upper flange and the lower flange define aligned interior openings. The openings have a length and an active transverse dimension. A
transrnission window is formed from a flat foil sheet material of sufficient length and width so WO 92/03839 2 ~ 8 9 6 4 3 pcr/us91/o58q5 ~; 7 that after fo~na~on the window covers the aligned in~crior openings of the upper and lower flan~es and window m~unung mechanism. The window is of a predetern~ined thickness. The transmission window is rcmovably mountable between ~he upper flange and the lower flange, such that ~he ac~ive area of the transmission window is at least 0.6 square inches, and such 5 that the window is capablc of withstanding energy deposition from the bcam of at least 50 wa~ts per square inch for a pcriod of at least 1 hou; without mechanical failore. Preferably, the window has an activc area of a minimum of at least 1 square inch, for exa~ple 5 s~uare inches, and most prefe~ably an active area of 10 sguare inches; and it can withstand an energy flux from the beam of at least a minimum of about 75 watts per sguare inch, ~or cxample 100 10 wa~ts per square inch, especially 125 wat~s per square ineh, ~nd most prefesably at leas~ 150 watts per square inch.

As s~ll a fur~her facet of the present invendon, a liquid material processor includes a housing containing a particle beam accelerator defining a vacuum chamber, a palticle beam 15 generator for gene~ting a particle '~am wi~in the vacuum cham'oer, a paTticle beam focusing and direcdng structure for dirccting the particle 'oeam toward a radiahon ernission end of the ~acuum cham'oer, tne housing including a Iransrnission window at the radiation emission end for passing ~e particle be~drn and being formsd of thin foil sheet material. ln ~his ~acet of the invention, the processor comprises a source for supplying a quantity of liquid matenal tO the 20 housing, a liquid material flow directing structure within the housing and external to the vacuum charn'oer for directing a flow of liquid material supplied from the source against an exterior surface of the transmission window in order to transfeir heat from the ~ransmission ., . j, . . .. ... .
window to the liquid cooling fluid while simul~aneous exposur~i to ~he particle beazn modifies cherrucally the liquid cooling fluid, thereby resulting in proccssing of the liquid cooling fluid 2~ into processed liquid, and a liquid collection vessel within uhe housin~ for collecting the processed liquid.
~, .. . ... . .
As one aspect of this facet of the invention, the liquid collection vessel defines a gaseous cavity above a liquid level, and the processor further comprising a pump9 such as a 30 vacuum pump, in communication with the gaseous cavity for reducing gas pressure within the cavity.
, ..... ~ ,................................................... .
As ~nother aspect of this facel of the in~ention, a heat exchanger is provided for ; exchanging heat from the processed liquid uithin the liquid collection vessel to the supply of 35 liquid material within the source. ~

As a further aspec~ of this facet of the invention, the housing includes plural flanges, each flange defining a cur~e locus in an active transverse dimension lying in a plane .

.
. .

,. . .

wo 92/03~3 8 ~ ~ ~ 3 Pc~ JS~l/058~5 substantially pcrpendicular to a longitudinal dirnension. The ~nsmission wind~w is of a size sufficient follow~ng foIrnatioll to enclose the curve locus of the plural flanges and extends therebetween in the longitudinal dimension and is of a predctermined thickness. Further, the transmission w~ndow is removably mowltable betwecn and posi~ioned by the plural flanges S such that the curve locus followed by the ~ansmission window has a radius of curvature which does not exceed twice the length of the aclive transverse dimension.

As a related aspect, the liquid material direc~ng s~ructure causes the flow of liquid matenal to be direc~cd in accordance with an ac~ve ~nsvcrsc dimcnsion of the transm~ssion window. As a further rclated aspeet, the liquid material directing struc~re comp~ises a knife-blade edge posi~oned adjacent to an edge of the activc t;ransverse dimension. ln one rnore related aspect, the knife-blade cdge is adjustably posiuonable in s~rder to control thickness of a liquid sheet of the liquid cooling fluid as applied tO cool the transmission window while undergoing ~he chernical processing.
In accordance with a further &cet of the present invcn~ion, a method is provided for processing materials by exposure to an accelerated particle beam. The method essentially comprises the steps o generating a particle beam within a vacuum charnber, directing ~he paTticle beam toward a particle bearn transmission window at a radiation er;nission end of the vacuum chamber, supplying from a source a quantity of said material to ~e processed within a fluid medium, such as a liquid, ~- directing a flow of the fluid medium supplicd from the source against an exterior surface of the par~cle bearn transmission window an order to transfer heat there~rom to the medium, simultaneously exposing the material in the fluid medium to accelerated particles of said particle beam passing through the transmission window means in order to process the material. . -~ . . ; . -. ~, . ~ ~ i . .. - . . . . .
As one aspect of this facet of the invention, the step of exposing the materiàl to al~celerated particles of the par~icle beam causes chernical modification of the material.

As another aspect of this facet of the invention, a funher step is provided for collecting 35 the fluid mediurn and processed material after heat transfer`to the medium and simuilaneous exposure of the matenal to the accelerated pamcles.

`: :
t ~; ~ ~ , .. ' ' WO 92/03839 2 ~ g 9 PCl/US91/058q5 As one more aspect of this face~ of the invention, the medium itself comprises the ma~erial tO be processed.

As yet anothcr aspect of this facet of ~he invention, ~u~ther steps include: providing an S enclosed processing charnber including the extcnor surface of the particle bearn transrnission v indow, and reducing gas pressure within the enclosed processing chamber to T~lieve s~resses i: ;he particle bcam transrrussion window.

As a still further aspect of this ~acet of the inven~on, a fur~her stcp of exehang~ng heat 10 from ~he fluid medium to an extemal heat transfer medium is ca~ied Ollt.

Yet another aspect of this facet of the invention includes the further step of forming the par~icle bearn transmission window means as a curved structure so that said external surface thereof has an active area al ~g at least part of its length so ~at a locus of a curve in cross 15 section along an active transverse dimension of the active area has a radius of cuTvature R of at least a portion of the cu~ve in cross section less than twice the length of the formation transverse dimension.

Still one more aspect of this facet of the invennon includes the step of forming the 20 particle beam ~ansmission window means as a curved structure to ~ollow guiding surfaces of plural flanges, each flange haYing a guiding surface defining a curve locus in an active ransverse dimension 1y~ng in a plane substantially peTpendicular to a longitudinal dimension, the particle beam transmission window being of a size sufficient following formation to enclose the curve locus of the plural flanges and extending therebetween in the said 25 longitu~inal dimension and being of predetenTlined thickness.
..
As still one more aspect of this facet of the invention, the step of directing the flow of fluid niedium includes the step of directing the flow of fluid medium to be directed in accord~nce with an acnve transverse dimension of the parncle beam t~ansmission window. As 30 a relatéd aspect, ihis step includës forrning and di~cting a the fluid modium as a thin sheet of liquid against the par~icle beam transmission window along a longitudinal edge thereof.
.. . , ., , ,, . ~ . ~, .. , . ~ .. . ..... .. . .
- As one more aspect of this facet of the invention, funher steps of collecting the fluid med~um ~ollowing heat transfer frorn the par~icle beam transmission window; and, transfelTing 35 heat from the collecte rnedium to said quantity of the material to be processed within the medium before it is directed against the particle beam transrnission window, are carried out.
: - , . .

': ', ~ . ~ :.' . : r - ,: ' . : ~
~ . .
,:, . . . :, , ;;

wos2/æ~9~3 PCr/US~1/05~
lo These and other obje tS, advantages, aspects and features of the present invention will be more fully understood and appreciated upon consideration of the following detailed description of a pre~erred embodiment, presented in conjunction with the accompanying drawings.
Bnçf I)~çription of ~Qprawin~5 .
ln the D~awings:
Fig. I is an ~xploded isometric view of a transmission window for a par~icle accelerator which incoTp~rates the principles of the present invention.
Fig. 2 illustrates a transmission window of the invention which is contoured at each end by a preforrn in order to present a curved convex surface to the ~acuum chamber and facilitates ready installation.
Fig. 3 illus~ates a transmission window of the inven~on which has been preshaped tO
present a convex surface to the vacuum chamber and which can be mounted between substantially flat surfaces of the upper and lower window moulating flanges.
Fig. 4 is a somewhat diagramrnatic view in ~ansverse cross section and elevation of the Fig. I particle accelerator ~ransmission window moun~ed 2xtween ~n upper nange and a 20 lower flange, showing curved edges of the upper flange around which the transmission window is formed and supported, showing a nozzle for creating a sheet of cooling fluid directed IO pass adjacently against the curved transmission window, showing a beam absorption s~ucture below a strand or tubular workpiece, and showing a deflected and converged particle beam for ~adiation processing ~f the strand or tubular workpiece.
Fig. 4A is a view similar tO Fig. 4, except tha~ the Fig. 1 accelerated pMicle beam is deflected and not converged, and thç workpiece comprises a continuously moving shee2 passing below the beam.
' Fig. S is a somewhat diagrammatic view in cross sec~on and elevation of an alternative i preferred embodiment, illustrating a fluid cooling arrangernent for conduc~g heat away from 30 ~ the transmission window and for promoting centering of the wo~kpiece in the particle beam ` ~ passing thr~ugh thi lransmission window.
:Fig; 6 is a diagran~natie isometric view of an embodiment of the present invention including an upper flan~e and transmission window, and of a lower f!ange mounted to the upper iflange, whorein the lower flange is provlded with passagéways enabllng gaseous

3~ -coolirig fluid and ~ooling liquid to flow, thereby to conduct heat ~way from the o-ansmission window ànd thé vicini~y ~ ~e s~nd being treated widi pamclé beam radiàtion.
- Fig. 7 is a view in side élevatior~ and cross section of the Fig. 6 embodiment along the section line 7-7 in Fig. 6. r ':

', '~ ' ' ' ' :' `
- . . .
: ' . ' ' ~ " ' ; : ' ' .

WO 92/03839 2 0 ~ 9 6 4 3 P~r/US9l/058~l5 Fig. 8 is a ~ :grammatic isome~c vicw of a tubular par~icle beam w~ndow structure also emb~>dying ; principles of the present invention rnounted between two moun~ing flanges of an evacualed chamber of a parncle beam accelerator.
Fig. 9 is a view of the Fig. 8 tubular window mounted betwcen two mounting flanges 5 of an evacuated chamber of a par~cle beam accelerator.
Fig. 10 is an enlarged, somewhat diagram~c Y~ew in side elevation of modified structure for mounting the Fig. 8 tubular ~ransmission window and for directing a substan~al]y cylind~ically lay~d cooling fluid flow at the inside/ambicnt environment surface of the Fig. 8 nlbular window and for crea~ng an axially centralizcd low pressure rcgion in 2he 10 window for promoting centering of the product strand to be treated by particle beam bombardment.
Fig. 11 is a diagrammatic side view in section and elevation of a liquid materials processing bearn which cmploys the liquid matcrial bcing i~radiated also to cool the transmission window in accordance with prin(ciples of thc present inYention.
Fi,,. 12 is a slightly enlarged, cven more diagrammatic side view in section andelevation of the Fig. 11 liquid matexials processing particle beam.
Fig. 13 is a diagrarnmatic side view in section and elevation of a particle beampetrochemical processing system, also incorporating the principles of the present invention.
Fig. 14 is a diagrammatic side view in section and elevation of a transportable 20 environmental liquid process~ng system embodying principles of the present invenion.
Fig. 1~ is a ~aph of par~icle beam power for a given area beam transmission window and a fan~ily of p~ocess radiation dosages as a funcion of process fluids flow, wherein the process fluid rçmoves hcat f~m the transmission window in accordance wi~h the present . . .
invention. , ,~

etailed l ~escripion of PrefeTred EmbQ~ments , ~ . ... . .
, . . .. . .
~ "Window materials useful in this invention include but are not limited to alun~inum, 30 titanium, beryllium and other maserials such as o~ganic polymers or polymer composites, such as metal coated polyme~s, for exàrnple.

. Fig. I illustrates an improved transmission window assembly configuration which -~ reduces the Yalue of the Iransverse saess in the window foil material to a mùch lowér levè! by 35 reducing the radius of curvature over that of a nominally flat window configuration: - -ln Fig. i a par~icle beam accelerator 10 is provided for ir,radiating a wor3 piece, such asa continuous strand or filament lla. Altemative3y, a wor3cpiece sheet moving transver sely with ,~, ,,,,'' .
, .
, . : ~ . -~ ~. . .' ,, -.: .: :

wo 92/03~8~ ~ ~3 PCr/lJS91/05~5 respect to the window opening along a direction of movement locus rnarked by the arrow llb tnay also be'i~ iated by the accelerato~ 10 (see Fig. 4A discussed hereinafter).
The aceelerator 10 includes a housing 12 which provides an enclosure defining anS vacuum eharnber 21. A pa~icle bearn 13 is emitted frsm a source 15 within the housing 10 and is denot~d by ~e downwardly direeted arrows in Fig. 1. The particle beam 13 may be focused and dir~cted toward a thin titanium foil'window 14 by any suitable csnv,entional beam direedng means (not shown). Thus, the particle beam 13 from the accelerator 10 may be linearly eollimated and directed in conven~onal fashion, as shown in Figs. l, 2 and 4A, or it may be a swept and converged panicle ribbvn beam from an accelerator 10', in accorLanee with the teachings of the referenced and incorporased copending patent application Serial No.
07/569,329, now U.S. Patent No. and as shown in Fig. 4.

The foil window 14 is forsned into an elongated, generally U-shaped channel stlucture having a radius of eusvature R of the channel portion which ra~ius is pre~erably much smaller than preYiously existing in eonventional flat window configurations of the prior art in which any ~adius of curvan~e resulted from imposiion of a pressure differential between the arnbient air outside ~he window and the vacuum inside the window once the window was installed in the accelerator. The foil window 14 may be a preform, as depicted in Figs. 2 and 3 and discussed héreinafter, or it may be formed by following contour-forming peripheral surfaces ' of a window mounting structure.
.. ... ~ .
In one'`presently preferred forrn shown in Fig. 1,-the foil window 14 is mountedbetween an upper flange st~ucture 16 connected to or forming a part of the housing 12 and a 2~ detachable lower flange structure 18. A polymeric or metal 0-ring gasket 20 provides a suitable vacuum seal between the~foil window 14 and facing surfaces of the upper flange 16.
A continuous loop of wire' h'a'ving ~a diaméter of approximately 10 mils and formed of a suitable metalj such as tin, is presently preferred for providing a durable 0-ring gaskel 20.

A series of screws 22 pass through openings 24 in the lower flange and engage threaded holes 26 formed in ~e upper flange 16 in order to securely affix and seal the windov, 14 to the housing 10. The flanges 16 and 18 and associated structural elements described hereinabove may be formed as an assembly for retrofitting a conventional particle beam accelerator,;in order to achieve the advantages Jealized by practice of the principles of the present invention. Alternatively, the flanges 16 and 18 may be parts of a particle accelerator, such as ~he accelerator 10, which is specially designed ~o malce prac~ical and effective use of the present invention.

2 0 8 9 6 4 ~
f WO 92/03839 PCI/US91/OS8q5 The arrangement illustrated in Fig. 1 enables ready and ef~lcient replacement of the transmission window 14 and provides access to the interior vacuum chamber 21 defined by the housing 12. Con~our-forming peripheral surfaces of the upper and lower flanges 16 and 18 of this arrangement guide and direct the ~nsmission window 14 into an elongated, curved 5 window structure, which, for the same material thickness, is conside~ably stronger than the substantially flat tlansmission window strucn~s employed in the pIior an.

- For cxample, for a three inch wide window using conventional nat flanges in lieu of the flanges 16 and 18, the radius of curvature R after vacuum loading would typically have a 10 dimension of about six inches. Under ~hose samc conditions, a thrcc inch wide window 14, w-;len given a radius of curvature R of one and one half inches, manifcs~s significantly reduced material stTess in the thin foil of the window, the strcss being less than about one quarter the comparable stress prcsent in the vacuum loaded flat w~dow configuration.

Fig. 2 illustrates a ~ansmission window cm~odiment 14A of the present invention which presents a curvea convex surface to the vacuum charnber along a substannal part of its length. The window 14A may be fo~med thusly by the configura~on of the surfaces of the upper and lower flanges abutting thereto or it may be preformed to con~orrn closely with the abutting surfaces of the uppcr and lower flanges.
~ ;ig. 3 illustrates a transrnission window cmbodiment 14B of the present invention which presents a preformed curved convex surface to the vacuum chamber and which may be mounted between substantially flat surfaces of the upper and lower window flanges. ïn all of the embodirnents of this invendon Ihe window 14 may be preshaped to be thinner in those 25 ~egions through which the par~icle beam passes and thicker in those regions adjacent to the window secunng structure. ln the par~cular embodimen~ of the invention shown in Fig. 3, thinning of those regions of the window through which the par~icle beam passes is an advantageous result of certain methods of preshaping, such as drawing down over a fcrming surface, or fonning with pressure, vacuum, or intense magnetic field, for examples.
3 0 . . ~
With the new transmission window configuration illustrated in Fig. 1, it is therefore practical to reduce the thickness of the window by one half and thereby reduce hea~ dissipation of the, window ~y at least one half over that of the conventional flat window configura~on. An ; additional very significant advantage is a substantial reduction (about 50% in this exarnple) in 35 .~ angularity of scattenng of Ihe electrons as they traverse the window. Accelerator power may thereupon be increased to double the maximum value perrnitted by use of a conventional ~lat window and still retain an addi~onal fifty percem safety margin in window slreng~h.
.- .

J

,'.' ' .

'': ' . ' ' ~ ~ ~ 9 PCI/US91/OS84~S

Significant improvcments in forced air window cooling e~ficiency may also be realized, since cooling fluid (gas, rnist or liquid) may now be directed spuifically along the surface of tne c~ved window 14 flowing against and guided by the curvature. As shown in Fig. 4, a knife-blade edge nozzle arrangement 28 is ~ormed in the lower flange 18 along one edge of the curved window 14 and dirccts cooling fluid flow 29 from a passage 30 directly agains~ the ambicnt air side of the window 14 along its entire alea in a direction transverse to the longitudinal axis along which the product strand lla moves, as denoted 'Qy the arrows drawn adjacent to ~he window 14 in Fig. 4. (As also shown in Fig. 4, inside edges 17 of the upper flange structure 16 may be slightly curved tO provide a fo~ning surface for curving the window 14, as desired.) The shee~ of cooling fluid should enter the processing chamber tangential to the surface of curvature of the window 14 at the region of entry. lf the sheet is forrned and directed tOO shallowly away from the window, therc will 've dead air space adjacent to the window 14. If the sheet is formed and directed too steeply toward the window, excessive turbulence of the cooling fluid results.
A fluid cooled base 'oeam-absoJp~on structure 33 having deep cavities 35 is provided below the s~rand lla to absorb any stray retrmants of the beam 1 3A emitted in the swept and converged ribbon bearn generator 10'.

The stn~ctures lO' and lO shown in Figs. 4 and 4A manifest an improved angle of incidence for, and radial acceleration of, ~e cooling fluid stream 29 relaive to the window 14 which has a beneficial effect of reducing the boundary layer (which had been a limiting fac~or in cooling efficiency in prior art flat window configurations~. lmproved cDoling of the ~ansrnission window enables use of even higher accelerator power levels, since the radiation - 25 flux and hence the window powa loading may be increased with increased cooling efficiency.
..
. ~ Fig. 4A shows a more structurally detailed view of a preferred arrangement for directing the cooling stream 29 against the window 14 in the accelerator 10, as applied in a p~ocess for ilTadiating a sheet wcrkpiece 1 Ib moving in a direction relative to the window 14 30 as depictedA in the Fig. 1 diagramrnatic view.

Windows 14 of the configuration shown in Figs. 4, 4A1 5, 6 and 7 are best cooled b~
causing high velocity cooling fluid (e.g. air) to flow over thc surface ~hereof in a direction which is transverse tO the axial direction of product strand flow. In this manner the short air ......... .. .
35 cooling path and radius yield maximum air velocity while tninitnizing dispersion and volume ^flow. When this cooling method is practiced within the structure depicted in Figs. 4-7, the cooling air has a minhnal effect upon the temperature of the product strand passing through the ' . ,' , ': : :' `' ' :
, ~ .

, wo 92/03839 2 0 ~ ~ 6 ~ 3 PC~tllS()1/05~4~
..

window volume (i~adia~on zone) along the radial axis of the curved window 1~, as best shown in Fig. 5.

~he cooling air stream 29 may ~anspon a liquid agcnt, such as a water mist to the 5 outside surface of the window 14, so that the cooling liquid cvapo~tes in proximity of the window, ~hereby absoTbing ~he heat of vaporization to achicve addiaonal heat transfer and cooling of the heated window.

Evaporation of the cooling liquid at the window surface also sesults in a volume10 expansion of cooling gas and resulting turbulence which breaks up surface boundary layers which may otherwise ~orm and inhibit cooling efficiency. A nozzle alTangement 28 as shown in Fig. S may bç employed to inject water-or other liquid, solid or par~icula~e material to be processed by exposure to the par~icle beam, onto the airstream in the airflow path 30 and thereby be ca~Tied into direct proximi~y of the surface of the window 14.
..,- 15 Further advantages may be obtained by reduction in the par~cle beam dimensions and by reducing the radius of curvature of the window 14. ln fact, a preferred species of the present invention is a tubular window as depicted in Fig. 8 and discussed hereinafter. These advantages are particularly evident in realizing efficient yct smaller sized, lower prime COSt par~icle beam accderators.

- . .- For electron cnergics ovcr, 150 KeV the cnergy losses of ~he elec~on beam in the : ~I window 14 are rcduced, for example, by about 19,000 electron volts for each .001 inch reduction in thickness of a titanium alloy window, wherein titanium is alloyed with vanadium ;' 25 and aluminum. This saving is particularly useful in lower energy accelera~ors, such as those '-' operating in a range between about 100 and 500 KeV where the energy loss within the window is most significant.' . ,.; Wi~h reference now.to Fig..~, a modifica~ion of the Fig. 1 accelerator lO is shown ' 30 which ,advantageously pTomotes self cenle~ing of the strand I I relative to the window 14, thereby optimaily positioning the strand .11 in the path of the particle beam for maximum , ~ ez.posure to the beam. In this modified accelesa~or 10', a region 37 of a modified lower flange ' ,.: 18' defines a longitudinal well ,or chamber 32 which oppositely faces the''windo~ 14.'This - c,han~n, el-shaped space 32 enables the, larninar aitflow sheet, depicted by a~Tows an~ ideri~ified ~, 35 , by~the reference numeral 34 to form into a spiral which surrounds the strand 11 and which creates a low pressure area at.the nominal axis of the strand 11 and a su~ounding high pressure area. This flow arrangemenl for the cooling stream 34 thereby no~ only effectively , - ~
.: ,. ,:
' ' . . . ', :

,, WO 92/03839 PC-r/us~l/058~
~ 9~43 16 draws heat off of and away from the curved transrnission window 14, it also promotes centering and proper axial alignment of the workpiece 11.

The st rucn~ral concept depicted in Fig. S is extended and presented in gr~ater detail in - Figs. 6 and 7. Therein, the base s~ucmre 18' is provided with a nitrogen or air ~lowpath 30, and also with a plurality of water flow passages 36. The spacc 32 is dcfincd by a box strucnLre 38 which is surroundcd by the water flow passages 36, so that the box s~uctyre 38 will be effcctively cooled by flow of water ~r other soitable coolant liquid ~rDugh the flow passages.

With referencc to Fig. 8 a transmission window has bcen formed as a cylindrical ~ube, - as by laser welding along a seam line (not shown). The product workpiece, such as she strand 11, is drawn through the inside space of the- tube, while irradiation from the par~cle beam, denoted by the arrows 13 is directed from an e~/acuatcd chamber side of the particle beam accelerator, throu~ ~hc thin tubular window 14' and to the strand 11.
Fig. 9 shows a mounting arrangement ~or mounting the tubular window 14' between two flanges ~0 and ~2 which position and sccure the tubular window 14' at opposite end regions thereof. Two threaded nuts ~4 and 56 compress ~espectively against the flanges 50 ~ and 52, thereby to lock the tube window 14' in place. llle flanges 50 and 52 are respectively 20 mounted through aligned openings forr,ned in two sidewalls 58 and 60 of a particle beam accelerator 62. The pardcle beam accelerator 62 generates and directs par~icle beams 13 from one or more emitters toward the window 14'. ,An interior space 64 within the particle beam accelerat,or 6~ is highly evacuated, whereas the "in~erior" space defined by the window tu'~e ~; 14' is exposed to the ambient environment. One can appreciate by inspection of Figs. 8 and 9 ~'; 25 that the tube,,geometry of the window 14' provides vas~ly reduced hoop stress across the severe pressure gradicnt f rom arnbient air pressure to the highly evacuated intenor space 64.

~' Cooling of ~e tube window 14' is an important consideration for its success and practicality.,C-.en~rally speaking, airflow induced under pressure may be applied to the interior -30,; of ,the tube 14' and ~ooduct away the heat generated as ~he particle 'oeam passes through the ~; ,.thin ,,window material. Also, in this exarnple a cooling liquid, such as a water mist, may be i; .injected at the periphery of, and ca~ied by, the pressurized airflow to the window surface, ,I ~,~thereby tO provide addi~onal cooling to the window by virtue of ~he heat of vaporization ? Als,o,~the expansion of volume resulting from evaporation of the moisture droplels'aids in 35 ;n breaking up s,urface boundary layers of gas at the window, thereby promoting more intimate , contact of the airflow with the window surface to be cooled.
': .~ , ~ 1 .' . ' .. : .
. , : ., ;

~o 92/03839 2 0 ~ 9 6 4 3 pcr/us91/o5845 Fig. 10 illustrates an improved cooling arrangement employing a coaxial air nozzle structure 66 within a modified ~hreaded nut 54'. The coa~ial air nozzle strucnlre 66 is disposed within an annular passage 68 defined in the modif1ed nut 54'. The passageway 68 communicates with a nipple 70 for attachment to a supply of cooling a~r, typically under a 5 pressure of 30 to 80 pounds pcr square inch. The coaxial air no771e structure provides a concentric nozzle annulus throughou~ its inner annular periphery which is directed ~oward the inside surface of the tubular window 14'. This nozzle cr@ates an annular, laycred airflow which passes against the tubular window 14 at high velocity. l:)ue to a venturi effect experienced within the interior of the tubc window 14', some air ~ro1uunc flow amplification - 10occurs. Because of this amplification, a low pressure region cxists in the ~roat of the window interior which self centers the s~nd 11 and facilitates initially fee~ng the st~and end into and th~ugh the window (so long as the di~ction of feed is the same as the ~c~on of laminar air flow).
15Rndi~on ' ocessin~ of W~indow Coolin~ M~terial For the processing of materials, such as the irradiation of an aqueous solution with toxic solutes for the p~pose of reduction of the toxic materials ~o less toxic or non-toxic forms, the window cooling air may carry or be in part or en~rely replaced with a fluid st;eam carrying material to 'oe processed by exposure to the cnergetic particle '~eam. While a liquid 20 medium is presently most preferred as a ca~ier medium for ea~ying (or comprising) the material to 'oe processcd, it is clear that particulates and other materials to be proeessed may 'oe injected into a fluid stre2m p.~vided for cooling the ~ansmission vnT~dow.
' , . j - .
' ,J~ The dimensions of the exit nozzle alTangement, i.e. cooling fluid nozzle opening 28 of 25 Fig. S or coaxial air nozzle s~ucture 66 of Fig. Iû, can be spaced so as to establish that the maximum stream thic cness flowing over the window is appropriate for the penet~.~tion depth of the energetic particle beam. . - - ~

Bearn window cooling callied out with a liquid component is much more ef~ecive than 3~ air cooling and therefore permits much higher beam nux tnrough the window. With a very high power beam, processing of very large amounts of material witnin a liquid medium or carrier may be achieved economically with a relatively low particle energy. Also, by employing a thin sheet of liquid-canried material to draw heat away from the transmission window, a thicker window may be employed. For exarnple, a window formed of 4 mil thick 35 foil may be advantag.-ously employed in the liquid materials process. While about 20 kilovolts per nil is lost to hea~ing in the window foil, t'nis heat is advantageously transferred to the liquid material to 'oe processed. At the same time, a more dur~ble transmission window struclure is realized by Yirtue of the increased tnickness of Ihe window malerial. Since liquid : . , , . . . ..

WO 92/0383~ 3 ~ 18 PCr/US91/05~5 has a much greater heat capacity, and since ~he w~ndow is being cooled by the liquid, rather than by airflow, a partial ~/acu~m may be pulled across the liquid side of the window which further reduces stresses in the window foil and adds robustness and longevity to the window and greater economy to the overall liquid process. l'hus, as the heat sapacity of the cooling 5fluid increases, the use~ul thickness of the thin window foil rnay likewise be increased.

Turning now to Pig. 11, a liquid materials processing particle bean~ system 100 includes a housing 101 enclosing a particle beam ernitter for emimng a paracle beam 102 from a sour~e (not shown in this figure). For liquids processing the bearn 102 most preferably rnay 10be deflected; and, it may also be deflected and converged in ac~ordance with the teachings of the referenced and incolpo~ated, and comrnonly assigned, co-pending U.S. Patent Applicanon Serial No. 07/569,329 filed on August 17, 1990, now lJ.S. Patent Alternatively, the beam 102 may be conventionally formed, focused, accelerated and 15deflected without convergence. ln any event, the bearn 102 is directed toward and through a curved transmission w~ndow 104 of the type previously described herein. While a cu~ved transrnission window 104 is presendy most preferred, it will be clearly understood by those slcilled in the art, that more conventional window structures, such as the slightly pillowed, nominally flat thin foil ~ansmission windows of the prior art, may also be employed with 20considerably increased efficacy within the system 100. If there is a vacuum on both sides of ; the window, then the window can be flat.
.. .. ; . . . . . .
- A liquid manifold 106 provides a supply of liquid 108 to ~e processed under suitable pressure.~The liquid 108 ~rom the liquid manifold 106 flows along one or more internal 25;passageways 110 toward a knife-blade edge structure 112 at one longitudinal periphery of the curved transrnission window 104. The knife-blade edge structure 112 forms and directs the - Ijquid IOX against the outside of the transmission window 104, thereby coming into contact ~` with it and drawing off the heat generated by passage of particles, such as electrons, therethrough.-;At the same time, the bearn's particles efficaciously pass into and prvcess the 30-liquid çmanating from the knife-blade s~ructure 110, thereby heating the liquid to a suitable process temperature and inducing other desired changes, either chemical,~as with petroleum cracking or chemical reduction of toxic compounds, or e.g. polymerization of other liquid . rnasenals, etc. ~
. - !, ! ' 35", After passing across the outer surface of the ~ansmission windou iO1 for heal transfer therefrom and for processing, the liquid 108 falls as a stream or expanding sheet in(o a collection vessel 114 defining an interior collec~ion space 116. The vessel 114 may advantageously be included within, or form a part of, the system housing 101. An outflou , ', .

WO 92/03839 2 0 8 9 6 4 3 : ~cr/us~l/0s8~s 11~ .i~aws the processed and heated liquid 108 out of the collection vessel 114, either for transfer or collec~on at a liquid receiver (not shown) or for heat cxchange and rccircula~on to the mlet manifold 106, as may be desiIed by a par~icular process.

S The interior space 116 may be evacuated in order to reduce the p~essure diffesemial or gradient across ~he thin foil ~ansrn~ssion window 104. By reducing the pressure within the collection vessel space 116 to e.g. about 5 pounds per square inch, or less, the s,~esses acToss the wmdow 104 are correspondingly reduced, and the window may be operated at a higher temperature, e.g. 350 degrees C., or higher. Particular choices of window materials and dimensions including thickness will depend on temperature, pressure dif~ç~ential, flow rates, heat capacity, ~iscosity, corrosiveness and other factors of ~he selected cooling fluid.

. As shown in Fig 12, the knife blade liquid sheet nozzle structure 112 may be positionably secured to an interior shelf 113 within the housing 101. Screws 115 may be provided to enable positional adjustment of the moveable knife blade structure 112 along a generally horizontal !ocus denoted by the double arrow locus line 117. When the blade assembly 112 is moved to the left in Fig. 12, the nozzle sheet orificc becomes smaller, and the liquid sheet directed at the thin titanium foil window lW itself becomes correspondingly thinner. Adiustment of the nozzle structure 112 IO the right widens the nozzle orifice and ; ` 20 thickens the shcet of process liquid being d~rected against ~he cun~ed cxterior surface of the window 104. Also to be noted in Fig. 12 are the bullnose upper flange 105 and lower securement flange 107 which secure ~e e.g. titanium foil window 104 to the housing 101.
.,.,~ , , .
Yet another liquid i~adiation and processing syslem 120 is illus~ated diagrammatieally in Fig. 13. The system 120 takes ad\rantage of the elevation of ~e tempera~ure of the irradiated liquid material in such a way ~hat a high energy efficiency may be attained. The system 120 includes a housing 122 having insulaled sidewalls and a parncle beam generator 123 which emits an energy beam 102 toward and through a thin foil transmission window 126, most preferably of the curved configuration discussed hereinabove, but which less preferably rnay be a convendonal flat surface transmission window.~

~i A collection cavity 128 within the housing 122 collects a liquid 130 undergoing processing within the system 120. Gases and vapors collecting in the cavitv i ~8 above the level of the liquid 130 are conducted ~.ria a pipe 132 to a low `iemperature`vapor conder~ser 134.
The vapor condenser 134 includes a coolant inlet lSI and a cooiant outflo~;l53 v~hich conducts coolant to and from the interior space of the condenser 134 in"orde`r to provide desired cooling of the vapors and consequent condensation thereof.

: . .. .

.. ..
, WO 92/031~ ~ 9 ~ 4 3 ~P~/US91/05845 A ~acuum pump 136 is provided in series with the cavity 128, pipe 132 and vapor condenser 134 so that the cavity 128 is evacuated. Condensed vapors are either passed out of the system 120 via a valve 138 to an exit conduit 140, or the condensate may b~ returned as a viscosity reducer to a m~in fluid stream via a valve 142 and pipe 143 which communicates with a pr~ess ou~low conduit 144 and flowpath. Advanuageously, Ihe process of evacuating the vapor por~on of the cavity 128 removcs e.g. oxygen and other reaclive gases and vapors from the process ~hereby preventing such gases from interfering with the desired process result. As noted above, a still further significant advantage of evacuating the cavity 128 is that the reduction in pressure to about S psia or less, for example, advantageously reduces the axial and transvcrse stresses othcrwise present at the transrnission window 126. These lower s7iresses make it possible to operate the process at very high window temperatures7 such as 350 degrees C, or higher, without rupture of ~he thermally weakened thin foil of the window.
Not shown in Fig. 13 are other temperature heating/cooling contr~ls and s7i~ucture which may be required or included for ~egulating the temperatures of cer~un liquid process materials, 1~ depending on the particular rnaterials and the desired process temperatures.

A process inlet 146 enables unprocessed liquid, such as highly visc~us crude oil, to enter a therrnally graded heat exchanger section 143 of the housing 122. A series of thermally insulative flow baffle plates 147 separate the interior of the section 143 into a senes of thennal stages or levels. At the same time, an internal conduit 150 snakes around the baffle plates 147 : as shown in Fig. 13.
,. ,; , , , .~
Fluids such as heavy crude oils rnay have very high viscosi~es. To accommodate high viscosity of the process liquid material, the conduit 150 is preferably divided into a senes of 25 progressively srr~aller diameter sections, with the largesl diameter section 150a being located at a lowennost, and coolest level within the graded heat exchanger 143. The temperature at the coolest level may be aboul 28 to 30 degrees C., for exarnple.
.. ..
~ iA next smaller diameter section I~Ob of the conduit 150 sinuously snakes throu~h a 30 middle, medium temperature por~ion of the heat cxchanger 143 where the tempera~ures may range from about 100 to 300 degrees C., for example; while a smallest diame~er section 146c extends through an uppermost, hottest portion of the graded heat exchanger 143 having temperatures ranging from 300 to 500 degrees C.: Af~er leaving the uppermosi level, ihe . iseg~?ent 150c cornmunicates with a knife-blade nozzle structure 148 of ~e type discussed e.g.
35 in ~conjunctlon with Figs. 11 and 12, for example. In this manner the driving pressure for driving the liquid process material through the conduil 150 may be minimized by taking advantage of progressive reduction in hydraulic resistance with increasing tcmperature of the material.

WO 92/03839 2 0 8 9 6 4 3 PCr/US91/05845 2]

A self contained, transportable fluid process bearn system 160 is illustrated in Fig. 14.
Therein, a conventional tractor 162 and semi-2lailer contain a system liquid processor 164, power supply 166 and opcrator console 168. The diesel engine of the ~actor 162 may be used to power a generator to supply primary opcra~ing power for the power supply 166, or a separate genera~or may be provided. Hoses 170 and 172 respectively provide an inlet and outlet for material tc be processed and its camer fluid mediur;n.

The transportable system 160 may be made tO be very ruggcd, and safe, with 10 necessary radiation shielding, and it may also be rnade ~o be uscd without direct human operator supesvision and control. The system 160 may thus ~e taken to and used in oil fields for crude oil viscosity reduction and l~xal cracking to produce refined products for field use.
It may be used to lower the hydraulic horsepower required ~or pumping through pipelines. It may be taken tO and advantageously employed to seduce or eliminate toxic contaTninants in 15 waste streams or in potable water supplies.
, ~
Fig. l~ graphs fluid flow rate as a function of bearn power for an elec~ron beamliquids processor of fixed window area and employing the fluid flow to cool the paricle beam window in accordance with the principles of the present inven~ion. ln the Fig. 15 graph, the electron bearn operated in a KeV range of 150~400, and the liquid knife gap varied from about .OûS" to .M0". Beam scan width vaned f~m about 2 inches to 10 inches.

A screening test was per~ormed with apparatus similar to the Fig. 11 apparatus tO
determine the gross effects of beam dose, dose rate and ternperature upon the viscous characteristics of oil. The samples iIradiated were SAE 120 weight gear oil. Using a control yiscosi~y of loo~ and measuring viscosiiies of processed oil with a Brookfield viscometer using the HB3 spindle and a rotation of 100 RPM, viscosity reductions follbwing radiation processing ranged from 93 to 68, with some absolute error due tO limited quantity of oil. The tests included water spray cooling and some under vacuum conditions. At a dose (MRad) of 1.66, the viscosity reduced to 93. When the dose was raised to 1~ Mrad, the reduced viscosities ranged from 83 ~o 68. A similar lest was performed upon Venezuelan Heavy Crude with sirnilar resulls.

In surnmary, test results have suggested that reduction of viscosities of heavv crude oil from this process yields products which are similar to those expected to result ~rom a more conventiona~ petroleum cracking process. EssentialJy no new compounds were noted as a result of this process.

" ;, WO 92/~ 9 ~; 43 PCr/US~ 5845 , Having thus described an embodiment of the presenl invention, it will now be appreciated that the objects of the invention have been fully achieved, and it will be Imderstood . by those skilled in the art that many changes in construction and widely differing cmbodiments 5 and applications will suggest themselves without departing frorn the spirit and scope of the invention, as pardcularly defined by the following ~ laims.

- , .
- . : . :, .

: ., , ,, } ~ , . ...
i _ ~ r ; , ' ' ., " `. :.'''' ' ', ' :. ' , -' ' . ' ,~. " , : ' ' ' : ' :, ''. "'~ ,. , ' : ' , '" '' '

Claims (73)

What is claimed is:

1. A transmission window for a particle accelerator, the transmission window being of a thin foil having a predetermined thickness and having a predetermined length between a first end and a second end, and a width when laid flat as a sheet prior to forming, the window being formed to have an active area along at least part of its length so that a locus of a curve in cross section along an active transverse dimension of the active area has a radius of curvature R of at least a portion of the curve in cross section less than twice the length of she formation transverse dimension.

2. The transmission window set forth in claim 1 wherein the radius of curvature R is less than the length of the active transverse dimension.

3. The transmission window set forth in claim 2 wherein the radius of curvature R is not greater than approximately one half the length of the active transverse dimension.

4. The transmission window set forth in claim 1 wherein the thin foil is formed into a continuous wall tube geometry.

5. The transmission window set forth in claim 4 wherein the continuous wall tube geometry is formed by the process of welding two oppositely facing edges of the thin foil sheet together along a generally longitudinal seam line.

6. The transmission window set forth in claim 1 wherein the thin foil is preformed during a manufacturing process to follow said curve along at least a portion of an active longitudinal dimension, the said portion including the active area of the window.

7. The transmission window set forth in claim 6 wherein the preformed thin foil follows a convex surface of generally elliptical shape along the active longitudinal dimension of the transmission window.

6. A transmission window assembly for a particle beam accelerator including a housing defining a vacuum chamber, means for generating a particle beam within the vacuum chamber, means for directing the particle beam toward a radiation emission end of the housing, the transmission window assembly being secured at the radiation emission end of the housing and including:
plural flange means for defining aligned openings, each opening having a curve locus in an active transverse dimension lying in a plane substantially perpendicular to a longitudinal dimension of the window assembly at the radiation emission end, a transmission window means for passing the particle beam and being formed of thin foil sheet material of sufficient size after formation to enclose the curve loci of the plural flange means and to extend therebetween in the said longitudinal dimension and being of a predetermined thickness, the transmission window means being removably mountable between and positioned by the flange means, such that the curve locus followed by the transmission window means has a radius of curvature which does not exceed twice the length of the active transverse dimension.

9. The transmission window assembly set forth in claim 8 further comprising sealing gasket means disposed between the transmission window means and at least one of the flange means.

10. The transmission window assembly set forth in claim 8 wherein the radius of curvature of the window means is not greater than approximately the length of the active transverse dimension.

11. The transmission window assembly set forth in claim 8 wherein the radius of curvature of the window is not greater than approximately one half the length of the active transverse dimension.

12. The transmission window assembly set forth in claim 8 wherein the transmission window means is formed into a tube and mounted in the particle beam accelerator by and between the plural flange means.

13. The transmission window assembly set forth in claim 8 wherein the plural flange means comprise a pair of flanges: an upper flange secured to the emission end of the housing and a removable lower flange, the upper flange and the lower flange defining aligned interior openings having a length along the longitudinal dimension and defining the curve locus along the active transverse dimension at each end which is followed by the transmission window means.

14. The transmission window assembly set forth in claim 13 further comprising cooling flow directing means for directing a flow of gaseous cooling fluid supplied from a source against the surface of the transmission window means.

15. The transmission window assembly set forth in claim 14 wherein the cooling flow directing means causes the flow of gaseous cooling fluid to be directed as a stream transversely across the transmission window means.

16. The transmission window assembly set forth in claim 15 wherein the stream directed transversely across the transmission window means creates a relatively lower pressure region in the vicinity of a longitudinal axis along which a product strand is drawn for irradiation by the particle beam.

17. The transmission window assembly set forth in claim 14 further comprising cooling liquid injection means for injecting a liquid phase cooling material into the flow of gaseous cooling fluid such that evaporation of the liquid phase material promotes further cooling of the transmission window means.

18. The transmission window assembly set forth in claim 12 further comprising cooling flow directing means for directing a flow of gaseous cooling fluid supplied from a source against the surface of the tubular transmission window means.

19. The transmission window assembly set forth in claim 18 wherein the cooling flow directing means causes the flow of gaseous cooling fluid to be directed longitudinally adjacently along the tubular transmission window and wherein a product strand to be irradiated by the particle beam is drawn through the tubular transmission window in the same direction as the flow of gaseous cooling fluid stream.

20. The transmission window assembly set forth in claim 19 wherein the flow of gaseous cooling fluid directed along the tubular transmission window means creates a low pressure region in the vicinity of a longitudinal axis along which the product strand is drawn, whereby facilitating alignment and guidance of the strand passing through the transmission window means.

21. The transmission window assembly set forth in claim 18 further comprising liquid phase material injection means for injecting a liquid phase cooling material into the flow of gaseous cooling fluid such that evaporation of the liquid phase material promotes further cooling of the tubular transmission window means.

22. The transmission window assembly set forth in claim 8 further comprising liquid cooling fluid flow directing means for directing a flow of liquid cooling fluid supplied from a source against the surface of the transmission window means.

23. The transmission window assembly set forth in claim 8 wherein the cooling flow directing means comprises a knife-blade edge providing structural means positioned adjacent to an edge of the active transverse dimension for directing the cooling fluid as a sheet in substantial alignment with said active transverse dimension.

24. The transmission window assembly set forth in claim 23 wherein the knife-blade edge providing structural means is adjustably positionable in order to control thickness of a liquid sheet of the liquid cooling fluid.

25. The transmission window assembly set forth in claim 22 wherein properties of the liquid cooling fluid are modified chemically in a predetermined manner upon exposure to the particle beam while the cooling fluid is cooling the window means.

26. The transmission window assembly set forth in claim 13 further comprising liquid coolant passages formed in the lower flange and a supply of cooling liquid for supplying cooling liquid to the liquid coolant passages.

27. The transmission window assembly set forth in claim 8 wherein the transmission window means is preformed to follow the said curve locus along at least a portion of the longitudinal dimension.

28. The transmission window assembly set forth in claim 21 wherein the preformedtransmission window means is preshaped to follow a convex surface of generally elliptical shape along at least a portion of the longitudinal dimension.

29. A particle beam accelerator including a housing defining a vacuum chamber, means for generating a particle beam within the vacuum chamber, means for directing the particle beam toward a radiation emission end of the housing, the housing including plural flange means, each flange means defining a curve locus in an active transverse dimension lying in a plane substantially perpendicular to a longitudinal dimension, a transmission window means for passing the particle beam and being formed of thin foil sheet material of a size sufficient following formation to enclose the curve locus of the plural flange means and extending therebetween in the said longitudinal dimension and being of predetermined thickness, the transmission window means being removably mountable between and positioned by the plural flange means, such that the curve locus followed by the transmission window means has a radius of curvature which does not exceed twice the length of the active transverse dimension.

30. The particle beam accelerator set forth in claim 29 further comprising sealing gasket means disposed between the transmission window means and at least one of the plural flange means.

31. The particle beam accelerator set forth in claim 29 wherein the radius of curvature of the window is not greater than approximately the length of the active transverse dimension.

32. The particle beam accelerator set forth in claim 29 wherein the radius of curvature of the window means is not greater than approximately one half the length of the active transverse dimension.

33. The particle beam accelerator set forth in claim 29 wherein the transmission window means is formed into a tube and mounted in the particle beam accelerator by and positioned between the plural flange means.

34. The particle beam accelerator set forth in claim 29 wherein the plural flange means comprises a pair of flanges including: an upper flange at the emission end of the housing, and a removable lower flange; the upper flange and the lower flange defining aligned interior openings having a length along the longitudinal dimension and defining the curve locus along the active transverse dimension at each end followed by the transmission window means.

35. The particle beam accelerator set forth in claim 34 further comprising cooling flow directing means for directing a flow of gaseous cooling fluid supplied from a source against the surface of the transmission window means.

36. The particle beam accelerator set forth in claim 35 wherein the cooling flow directing means causes the flow of gaseous cooling fluid to be directed transversely across the transmission window means.

37. The particle beam accelerator set forth in claim 36 wherein the cooling flow directed transversely across the transmission window means creates a low pressure region in the vicinity of a longitudinal axis along which a product strand is drawn for irradiation by the particle beam.

38. The particle beam accelerator set forth in claim 35 further comprising liquid phase material injection means for injecting a liquid phase cooling material into the flow of gaseous cooling fluid such that evaporation of the liquid phase material promotes further cooling of the transmission window means.

39. The particle beam accelerator set forth in claim 33 further comprising cooling flow directing means for directing a flow of gaseous cooling fluid supplied from a source against the surface of the tubular transmission window means.

40. The particle beam accelerator set forth in claim 39 wherein the cooling flow directing means causes the flow of gaseous cooling fluid to be directed longitudinally adjacently along the transmission window means and wherein a product strand to be irradiated by the particle beam is drawn through the tubular transmission window in the same direction as the flow of gaseous cooling fluid.

41. The particle beam accelerator set forth in claim 40 wherein the cooling flow directed along the tubular transmission window means creates a low pressure region in the vicinity of a longitudinal axis along which the product strand is drawn.

42. The particle beam accelerator set forth in claim 33 further comprising liquid phase material injection means for injecting a liquid phase cooling material into the flow of gaseous cooling fluid such that evaporation of the liquid phase material promotes further cooling of the tubular transmission window means.

43. The particle beam accelerator set forth in claim 34 further comprising liquid coolant passages formed in the lower flange and a supply of cooling liquid for supplying cooling liquid to the liquid coolant passages.

44. The particle beam accelerator set forth in claim 29 wherein the transmission window means is preformed to follow the said curve locus along at least a portion of the longitudinal dimension.

45. The particle beam accelerator set forth in claim 43 wherein the preformed transmission window means is preshaped to present a convex surface of generally elliptical shape to the vacuum chamber.

46. The particle beam accelerator set forth in claim 34 comprising cooling flow directing means for directing a flow of cooling fluid supplied from a source against the surface of the transmission window means.

47. The particle beam accelerator set forth in claim 46 wherein the cooling flow directing means causes the flow of cooling fluid to be directed transversely across the transmission window means.

48. The particle beam accelerator set forth in claim 47 wherein the cooling flow comprises a liquid supplied from a source which is directed into direct proximity against the surface of the transmission window means by the cooling flow directing means.

49. The particle beam accelerator set forth in claim 48 wherein the cooling flow directing means comprises a knife-blade edge providing structural means positioned adjacent to an edge of the active transverse dimension.

50. The particle beam accelerator set forth in claim 49 wherein the knife-blade edge providing structural means is adjustably positionable in order to control thickness of a liquid sheet of the liquid cooling fluid.

51. The particle beam accelerator set forth in claim 48 wherein properties of the liquid cooling fluid are modified chemically in a predetermined manner upon exposure to the particle beam while the liquid cooling fluid is cooling the window means.

52. The particle beam accelerator set forth in claim 33 further comprising cooling flow directing means for directing a flow of cooling fluid supplied from a source against the surface of the tubular transmission window means.

53. The particle beam accelerator set forth in claim 52 wherein the cooling flow directing means causes the flow of cooling fluid to be directed longitudinally adjacently along the transmission window means and wherein a product strand to be irradiated by the particle beam is drawn through the tubular transmission window means in the same direction as the flow of the cooling fluid.

54. A liquid material processor including housing containing a particle beam accelerator means defining a vacuum chamber, means for generating a particle beam within the vacuum chamber, means for directing the particle beam toward a radiation emission end of the vacuum chamber, the housing including transmission window means at the radiation emission end for passing the particle beam and being formed of thin foil sheet material, the processor comprising:
source means for supplying a quantity of liquid material to the housing, liquid material flow directing means within the housing and external to the vacuum chamber for directing a flow of liquid material supplied from the source means against an exterior surface of the transmission window means in order to transfer heat from the transmission window means to the liquid cooling fluid while simultaneous exposure to the particle beam modifies chemically the liquid cooling fluid, thereby resulting in processing of the liquid cooling fluid into processed liquid, and liquid collection means within the housing for collecting the processed liquid.

55. The liquid material processor set forth in claim 54 wherein the liquid collection means defines a gaseous cavity above a liquid level, and further comprising negative pressure providing means in communication with the gaseous cavity for reducing gas pressure within the cavity.

56. The liquid material processor set forth in claim 55 further comprising heat exchanger means for exchanging heat from the processed liquid within the liquid collection means to the supply of liquid material within the source means.

57. The liquid material processor set forth in claim 54 wherein the transmission window means comprises a thin foil having a predetermined thickness and having a predetermined length between a first end and a second end, and a width when laid flat as a sheet prior to forming, the transmission window means being formed to have an active area along at least part of its length so that a locus of a curve in cross section along an active transverse dimension of the active area has a radius of curvature R of at least a portion of the curve in cross section less than twice the length of the formation transverse dimension.

58. The liquid material processor set forth in claim 57 wherein the housing includes plural flange means, each flange means defining a curve locus in an active transverse dimension lying in a plane substantially perpendicular to a longitudinal dimension, the transmission window means being of a size sufficient following formation to enclose the curve locus of the plural flange means and extending therebetween in the said longitudinal dimension and being of predetermined thickness, the transmission window means being removably mountable between and positioned by the plural flange means.

59. The liquid material processor set forth in claim 57 wherein the liquid material directing means causes the flow of liquid material to be directed in accordance with an active transverse dimension of the transmission window means.

60. The liquid material processor set forth in claim 59 wherein the liquid material directing means comprises a knife-blade edge providing structural means positioned adjacent to an edge of the active transverse dimension.

61. The liquid material processor set forth in claim 60 wherein the knife-blade edge providing structural means is adjustably positionable in order to control thickness of a liquid sheet of the liquid cooling fluid.

62. The liquid material processor set forth in claim 54 included within mobile transportation means for enabling transportation and relocation of the liquid material processor as a unit to a plurality of process sites.

63. A method for processing materials by exposure to an accelerated particle beam, the method comprising the steps of:
generating a particle beam within a vacuum chamber, directing the particle beam toward a particle beam transmission window means at a radiation emission end of the vacuum chamber, supplying a quantity of said material to be processed within a fluid medium, directing a flow of fluid medium supplied from the source means against an exterior surface of the particle beam transmission window means in order to transfer heat therefrom to the fluid medium, simultaneously exposing the material in the fluid medium to accelerated particles of said particle beam passing through the transmission window means in order to process said material.

64. The processing method set forth in claim 63 wherein the step of simultaneously exposing the material to accelerated particles of said particle beam causes chemical modification of said material.

65. The processing method set forth in claim 63 comprising the further step of collecting the fluid medium and processed material after heat transfer to said fluid medium and simultaneous exposure of said material to said accelerated particles.

66. The processing method set forth in claim 63 wherein said fluid medium comprises said material to be processed.

67. The processing method set forth in claim 63 comprising the further steps of providing an enclosed processing chamber including the exterior surface of the particle beam transmission window means, and reducing gas pressure within the enclosed processing chamber to relieve stresses in said particle beam transmission window means.

68. The processing method set forth in claim 63 comprising the further step of exchanging heat from the fluid medium to an external heat transfer medium.

69. The processing method set forth in claim 63 comprising the further step of forming the particle beam transmission window means as a curved structure so that said external surface thereof has an active area along at least part of its length so that a locus of a curve in cross section along an active transverse dimension of the active area has a radius of curvature R of at least a portion of the curve in cross section less than twice the length of the formation transverse dimension.

70. The processing method set forth in claim 69 wherein the step of forming the particle beam transmission window means as a curved structure includes the step of forming the particle beam transmission window means with plural flange means, each flange means defining a curve locus in an active transverse dimension lying in a plane substantially perpendicular to a longitudinal dimension, the particle beam transmission window means being of a size sufficient following formation to enclose the curve locus of the plural flange means and extending therebetween in the said longitudinal dimension and being of predetermined thickness.

71. The processing method set forth in claim 63 wherein the step of directing the flow of fluid medium includes the step of directing the flow of fluid medium to be directed in accordance with an active transverse dimension of the particle beam transmission window means.

72. The processing method set forth in claim 71 wherein the step of directing the flow of fluid medium includes the step of forming and directing a sheet of the fluid medium against the particle beam transmission window means along a longitudinal edge thereof.

73. The processing method set forth in claim 63 comprising the further steps of collecting the fluid medium following heat transfer from said particle beam transmission window means;
and, transferring heat from said collected fluid medium to said quantity of said material to be processed within said fluid medium before it is directed against said particle beam transmission window means.