- bergoz Instrumentation
Contents
1. Very low ringing when it is properly installed See Installation on the vacuum chamber in this manual FCT limitations The FCT like all passive transformers differentiates the signal When the pulses to be observed are longer than a few microseconds the droop of the FCT becomes excessive The FCT has eddy current loss up to a few percents Eddy current losses are frequency dependent increase towards the higher frequencies Yet the FCT is still the best instrument to visualise a short fast pulse on an oscilloscope when non contact measurement is a necessity particle beams high voltage etc BERGOZ Instrumentation Fast Current Transformer 01630 Saint Genis Pouilly Farnce User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 4 OPERATING PRINCIPLE N turns Output ita 50 _____ O Primary al 50 ohms current lt gt No Inside FCT User connection SPECIFICATIONS Fastest wideband WB models Technology Predominantly amorphous Turns ratio Sensitivity nominal Rise time typ Droop Upper cutoff frequency 3dB typ Lower cutoff frequency 3dB Position sensitivity on axis L R time constant min Max charge pulse pulses 1ns Max peak current pulses gt 1ns Max rms current Low droop LD models Technology Predominantly nanocrystalline Turns ratio Sensitivity nominal Rise time typ Droop Upper cutoff frequency 3dB typ Lower cutoff frequency2. ada ane sara vues EUNDI SR SPECIFICATIONS eeu cu cae iN ud ated mI CU D MU P EM A IM cu E Passive EG T oodd eM Iu ee Active Amplification 46 221222 ceeo desse eov epo see ee ELECTRICAL CONNECTION S 2 uestes wesood de eeu eto Mu bo even entendue Coaxial CONNEC OS ur sca cuss Goa loses saw anil fox Sou ane one Loro DID ren S D D D ND Oo Power supply connections Active FCT only OUTPUT SIGNAL POLARITY s eue eeu E ot E re tn re COAXIAL CABLE SELECTION nent One dea ERR Re Sn A NM RM ANE MECHANICAL DIMENSIONS 3eme se esa aee ne E RES INSTALLATION GENERA soc eoe tede eue seen oes nnus ee tas eere doe dee ads INSTALLATION ON A VACUUM CHAMBER eem Break in the vacuum chamber electrical continuity Vacuum chamber Tiipedante 2s ASS ee ede acca eeu E ARS ERN te Wall current by pass and RF shield Thermal protection of the IC T eacus unis en tee Keeping high harmonics of the beam out of the cavity BICC IOS tai shreldis Se nn ed Ete Pt 1 FCT RADIATION RESISTANCE eeiecacocsaeu a un sas swe taadecedegeeoasaessesys 12 Om O0 ooN I ON OO Un Enr En A A AA QQ BERGOZ Instrumentation Fast Current Transformer 01630 Saint Genis Pouilly Farnce User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 2 INITIAL INSPECTION It is recommended that the shipment be inspected immediately upon
3. on the outside of a vacuum chamber requires some precautions a The electrical conductivity of the vacuum chamber must be interrupted in the vicinity of the FCT otherwise the wall current will flow thru the FCT aperture and cancel the beam current b The wall current must be diverted around the FCT thru a low impedance path c A fully enclosing shield must be installed over the ICT and vacuum chamber electrical break to avoid RF interference emission d The enclosing shield forms a cavity Cavity ringing at any of the beam harmonics must be avoided e The FCT must be protected from being heated beyond 80 C during vacuum chamber bake out f The higher harmonics of the beam should be prevented from escaping the vacuum chamber because 1 they are not seen by the FCT therefore unnecessary 2 they heat the FCT and any other conductive material inside the cavity 3 they cause quarter wave mode ringing in the cavity Note The FCT does not need to be protected from external magnetic fields When it is exposed to external magnetic fields it may saturate this causes the droop to increase up to a factor of 2 It has no effect on the FCT linearity Break in the vacuum chamber electrical conductivity If the vacuum chamber does not require bake out and the vacuum requirements are moderate a polymer gasket in between two flanges is adequate to assure the desired galvanic isolation If the vacuum chamber needs bake out the most com
4. 3dB Position sensitivity on axis L R time constant mim Max charge pulse pulses 1ns Max peak current pulses 1ns Max rms current BERGOZ Instrumentation Fast Current Transformer 01630 Saint Genis Pouilly Farnce User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 5 ELECTRICAL CONNECTIONS Coaxial connectors on the FCT toroid sensor and external box FCT model Ordering code Output connector type Standard ING SUR ernai du zo ee add dosd dado baa ew toad edd S SMA 50Q female BNC SR SUR cates sodas NS RS aes ea ecu en Sad BNC 50Q female Lemo So SUTIIN Se Du Eo wank duit Casas Paces week ed Lemo 00 50Q female N type SIN SUK s che totiaa mee yeeneucey ve goat ute re dec N 50Q female On above models the body of the connector is connected to the shield Twisted pair EW SULT TC No connector On the twisted pair model the winding is isolated from the shield OUTPUT SIGNAL POLARITY The Fast Current Transformer is bipolar Arrows are printed on the outer surface of the toroid Charges positive crossing the aperture in the direction of the arrow give positive outputs E g an electron beam passing in the direction of the arrow yields a negative output COAXIAL CABLE SELECTION The FCT output is a wideband signal up to and beyond 2 GHz If the integrity of the signal must be preserved the cable must feature a bandwidth commensurate to the signal frequency spectrum Some examples Cable length Adequa
5. Bergoz Instrumentation Espace Allondon Ouest 01630 Saint Genis Pouilly France Instrumentation Tel 33 450 426 642 Fax 33 450 426 643 Visit our web site at http www bergoz com Fast Current Transformer User s Manual Rev 3 1 Japan U S A REPIC Corporation GMW Associates 28 3 Kita Otsuka 1 Chome 955 Industrial Road Toshima ku Tokyo 170 0004 San Carlos CA 94070 Tel 03 3918 5326 Tel 650 802 8292 Fax 03 3918 5712 Fax 650 802 8298 sales repic co jp sales gmw com BERGOZ Instrumentation 01630 Saint Genis Pouilly France Tel 33 450 426 642 Fax 33 450 426 643 email bergoz Q bergoz com http www bergoz com Registre des M tiers Bourg en Bresse Registre des ing nieurs Zurich TVA VAT IVA USt N FR88414997130 S rl capital 152K Siren 414 997 130 R C S Bourg APE 332B BERGOZ Instrumentation Fast Current Transformer 01630 Saint Genis Pouilly Farnce User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 1 SUMMARY Page PNTTTALANSPECTION Lii SMS A ne Ne e pet de ORA E SUR Md WARRANTY essem aestas t D EU D ee ASSISTANCE 4525222 ket EN REDE es ees SERVICE amp RETURN PROCEDURES ut ES ee en UI VASE SARE TY TNS TERUG TONS 03 ess ces ce P ea tL d E Se GENERAL DESCRIPTION 5 22 8 539322 EM IRE INE Sn cia eee FCT maim advanbig esi sco drieo tere diet dap ne e E id notre PCT rtallonse i ovo deret vasa Saas Wes EE dh aua a CH ua DU UE OPBERATINCEPRINCIPBIE 2
6. N 79 04 79 08 82 10 and 89 12
7. RADIATION RESISTANCE Fast Current Transformer User s manual Page 12 FCTs contain materials which may be damaged by ionizing radiations They are listed hereafter Organic and radiation sensitive materials used in the Standard sensor The Standard sensor is supplied when the Rad Hard option is not ordered Component Material Radiation resistance Wiring insulation Polyvinylchloride PVC 2 x 105 Gy Fiber glass gt 108 Gy with rubber adhesive gt 106 Gy Stress absorbent Silicon rubber tape SIR 5 x 105 Gy Silicon rubber SIR 2 x 105 Gy Connector isolation PTFE Teflon lt 103 Gy Organic and radiation sensitive materials used in the Rad Hard sensor The Rad Hard sensor is supplied when the Rad Hard option is ordered The ordering code and model number are then terminated by H Component Material Radiation resistance Wiring isolation Polyether ether ketone PEEK 6 x 107 Gy Fiber glass gt 108 Gy with rubber adhesive gt 106 Gy Stress absorbent Polyurethane foam PU 5 x 106 Gy Polyurethane rubber PUR 5 x 106 Gy Connector isolation Polyethylene PEX or 106 Gy Polyimid Kapton 6 x 107 Gy The above radiation resistance values are indicative only They do not imply any guarantee of whatever nature from the manufacturer The manufacturer specifically declines any responsibility for any damage direct or consequential caused by ionizing radiations 1 Compilation of Radiation Damage Test Data H Sch nbacher et al CER
8. RGOZ Instrumentation Fast Current Transformer 01630 Saint Genis Pouilly Farnce User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 3 SAFETY INSTRUCTIONS The instrument designated as Fast Current Transformer may become RADIOACTIVE when exposed to ionizing radiations Standard models contains Cobalt Me beo Ms Up to 0 4 Kg LI Eco RR Y EIU ES Up to 0 2 Kg GENERAL DESCRIPTION FCT is a passive device It contains no electronics Its model number has the syntax FCT DDD TT 1 Where DDD is the inner diameter mm e g 055 for 55 mm TT 1 is the turns ratio e g 10 1 for 10 turns Some suffixes may be appended to the model number LD for Low droop models WB for Wideband models H for Rad hard models Some special models include a floating calibration winding CAW xx suffix indicates a calibration winding of xx turns The passive FCT has a rise time faster than Ins Some models have risetime as low as 175 ps corresponding to 2 GHz upper frequency cutoff 3 dB The output signal is a current to be measured across a 50Q load The core is a composite of CoFe amorphous alloy and nanocrystalline alloy to optimize the frequency response and minimize ringing The CoFe alloy is specifically cross field annealed for this application FCT main advantages e The FCT displays the beam current with a minimum of distortion up to very high frequency It is therefore primarily an instruments to be used with an oscilloscope
9. delivery If it is damaged in any way contact Bergoz Instrumentation or your local distributor The content of the shipment should be compared to the items listed on the invoice Any discrepancy should be notified to Bergoz Instrumentation or its local distributor immediately Unless promptly notified Bergoz Instrumentation will not be responsible for such discrepancies WARRANTY Bergoz Instrumentation warrants its beam current monitors to operate within specifications under normal use for a period of 12 months from the date of shipment Spares repairs and replacement parts are warranted for 90 days Products not manufactured by Bergoz Instrumentation are covered solely by the warranty of the original manufacturer In exercising this warranty Bergoz Instrumentation will repair or at its option replace any product returned to Bergoz Instrumentation or its local distributor within the warranty period provided that the warrantor s examination discloses that the product is defective due to workmanship or materials and that the defect has not been caused by misuse neglect accident or abnormal conditions or operations Damages caused by ionizing radiations are specifically excluded from the warranty Bergoz Instrumentation and its local distributors shall not be responsible for any consequential incidental or special damages ASSISTANCE Assistance in installation use or calibration of Bergoz Instrumentation beam current monitors is available fro
10. he electrostatic shield should be grounded Different grounding conditions must be tried until the noise pickup is at its minimum The quality of the grounding thus the efficiency of the shield is determined by the impedance of the grounding scheme In practice its inductance is the parameter to minimize Note the noise picked up by capacitive coupling with the vacuum chamber is wideband noise It is best observed with a wideband oscilloscope while the accelerator is running The electrostatic shield can be made in any conductive metal provided the grounding cable connects properly the the shield It may have the dual purpose of thermal shield and electrostatic shield In this case one should take care that the cooling water pipes do not bring noise to the shield To hold the shield and the FCT sensor in place while providing good isolation the space between vacuum chamber shield and FCT sensor can be filled with polyurethane foam If the vacuum chamber requires high temperature bake out fiber glass wool will be preferred Note The ICT accuracy is not affected by its radial angular or axial position in respect of the beam axis Ferrite cores tubes and beads installed on the coaxial cable contribute significantly to eliminate the noise picked up by the ICT body via capacitive coupling Avoid the split cores when possible BERGOZ Instrumentation 01630 Saint Genis Pouilly Farnce Tel 33 450 426 642 Fax 33 450 426 643 FCT
11. m Bergoz Instrumentation 01630 Saint Genis Pouilly France It is recommended to send a detailed description of the problem by fax or email SERVICE PROCEDURE Products requiring maintenance should be returned to Bergoz Instrumentation or its local distributor Bergoz Instrumentation will repair or replace any product under warranty at no charge The purchaser is only responsible for transportation charges For products in need of repair after the warranty period the customer must provide a purchase order before repairs can be initiated Bergoz Instrumentation can issue fixed price quotations for most repairs However depending on the damage it may be necessary to return the equipment to Bergoz Instrumentation to assess the cost of repair RETURN PROCEDURE All products returned for repair should include a detailed description of the defect or failure name and fax number of the user Contact Bergoz Instrumentation or your local distributor to determine where to return the product Returns must be notified by fax or email prior to shipment Return should be made prepaid Bergoz Instrumentation will not accept freight collect shipment Shipment should be made via Federal Express or United Parcel Service Within Europe the transportation service offered by the Post Offices EMS Chronopost Datapost etc can be used The delivery charges or customs clearance charges arising from the use of other carriers will be charged to the customer BE
12. monly use solution is to braze a section of ceramic on the vacuum chamber tube This is called a ceramic gap The ceramic gap may be installed on centre or off centre of a short pipe section Flanges Ceramic gap BERGOZ Instrumentation Fast Current Transformer 01630 Saint Genis Pouilly Farnce User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 8 INSTALLATION ON THE VACUUM CHAMBER Cont d Vacuum chamber impedance The ceramic gap causes a disruption of the impedance seen by the beam On leptons accelerators this is particularly detrimental to emittance The most usual corrective measure consists of metallizing the inside of the ceramic gap Metallization has been used successfully used on many electrons positrons accelerators Depending on the type of current transformer being installed AC or DC the resistance of the desirable metallization varies FCT current sensors tolerate a metallization with ca 1Q without problem provided the wall current bypass is of very low impedance If a DC current transformer PCT or MPCT S is installed over the same ceramic gap these instruments are adversely affected by an ohmic value R lt 100Q because it shorts the PCT or MPCT modulator windings The commonly used solution is to etch a narrow groove in the metal deposit to prevent DC conductivity of the gap metallization Wall current bypass and RF shield The two functions of wall current by pass and RF shield can be perfo
13. nce of the ceramic gap while the lower frequencies will enter the cavity and induce a flux in the transformer core Note that the full charge of the wall current pulse passes thru the cavity irrespective of the value of the gap capacitance The value C of the gap capacitance determines the higher cutoff frequency of the wall current entering in the cavity The 3dB point is obtained when the impedance of the cavity Zeavity is equal to the impedance of the gap Zap The impedance of the wall current bypass itself can be ignored because it is much lower than the transformer s reflected impedance therefore N turns Output leor 50 T Primary TNI i 50 ohms current EP S Inside FCT User connection Ze R N2 where R is the load impedance of the transformer 25Q 50Q termination 50Q internal load N is the transformer s turns ratio Example an FCT with 20 1 turns ratio i e FCT XXX 20 1 Zaeavity 0 0625 Q BERGOZ Instrumentation Fast Current Transformer 01630 Saint Genis Pouilly Farnce User s manual Tel 433 450 426 642 Fax 33 450 426 643 Page 10 Keeping high harmonics of the beam out of the cavity Cont d The gap impedance is determined by its capacitance Zap 1 C and o 2nf For Zeavity Zgap 1 C2 N2 2nfR Example FCT with 20 1 turns ratio f 3as 1GHz R 2250 C 2 54 nF Different accelerator laboratories use different techniques to obtain the required gap capacitance A simple method co
14. nsists in building a capacitor over the ceramic gap with layers of copper foil separated by layers of 100um thick kapton foil To obtain the desired capacitance value the overlapping area is obtained by S Cd o Where C is the capacitance F S is the area m7 d is the dielectric thickness m r is the relative dielectric constant 3 5 for Kapton polyimid o is the dielectric constant 8 86 x 107 Example for C 2 54 nF and d 100um and r 3 5 S 82 cm2 Other laboratories install a capacitive gap bypass with surface mount capacitors distributed over the slit The capacitive bypass is made in two halves for ease of mount slit smd ceramic capacitors Capacitive gap bypass water hose clamp lower half vacuum chamber BERGOZ Instrumentation Fast Current Transformer 01630 Saint Genis Pouilly Farnce User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 11 Electrostatic shield Electrostatic capacitive coupling between the FCT body and the vacuum chamber must be avoided This is especially true for high sensitivity FCTs like FCT XXX 05 1 An electrostatic shield may be installed FCT Electrostatic shield Vacuum chamber cle Low impedance ground The shield must be grounded on one side only Depending on the cables layout grounding on one side will increase the noise pick up while grounding on the other side will decrease it There is no easy way to predict on which side t
15. rmed by a solid copper or aluminum shield attached to the vacuum chamber on either side of the electrical break A cylindrical enclosure which splits into two half shells is the easiest solution The shells can be firmly attached to the vacuum chamber with water hose clamps Thermal protection of the FCT The FCT must not be heated beyond 80 C If the vacuum chamber requires bake out a thermal shield must be installed between the vacuum chamber or the heating sleeves and the FCT The thermal shield can be a simple copper cylinder cooled by water circulating in a copper tube brazed onto the cylinder The water circuit must not pass thru the FCT aperture It must enter and go out on the same side of the FCT otherwise it makes a shorting loop around the FCT toroid BERGOZ Instrumentation Fast Current Transformer 01630 Saint Genis Pouilly Farnce User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 9 Keeping high harmonics of the beam out of the cavity The transformer the gap capacitance and the wall current bypass form together a cavity It is important to prevent unnecessary harmonics from entering the cavity The beam current flows thru the vacuum chamber The wall current follows the conductive vacuum chamber walls Transformer Ceramic gap gt lt eee Wall current bypass The transformer sees the wall current Iw The higher frequencies of the wall current frequency spectrum will pass thru the capacita
16. te cable technology Manufacturer type RG 58 Low loss RF cable Suhner S 12272 04 Above 50 m Foam dielectric cable Cellflex Air dielectric cable Flexwell Heliax BERGOZ Instrumentation Fast Current Transformer 01630 Saint Genis Pouilly Farnce User s manual Tel 433 450 426 642 Fax 33 450 426 643 Page 6 MECHANICAL DIMENSIONS FCT Order codes XX 1 turns ratio FCT 016 XX 1 FCT 028 XX 1 FCT 055 XX 1 FCT 082 XX 1 FCT 122 XX 1 FCT 178 XX 1 FCT XXX 05 1 FCT XXX 10 1 to 100 1 INSTALLATION GENERAL The metal shield of the FCT toroid sensor must be isolated from the local ground because its grounding creates a ground loop with the oscilloscope ground or the power supply ground in the case of an active FCT From the standpoint of external noise pickup it is advantageous to install the external box as close as possible from the FCT sensor External noise picked up by the FCT cables can often be attenuated by common mode chokes This applies to the coaxial cables and to the power supply twisted pair A common mode choke consists in passing the cable up to 6 7 times thru a ferrite core The ferrite must be selected for its high core loss at the noise frequency to be attenuated BERGOZ Instrumentation Fast Current Transformer 01630 Saint Genis Pouilly Farnce User s manual Tel 33 450 426 642 Fax 33 450 426 643 Page 7 INSTALLATION ON A VACUUM CHAMBER The installation of a Fast Current Transformer FCT
Download Pdf Manuals
Related Search