IAEA-TECDOC-913 Manual troubleshootingfor and upgrading neutronof generators INTERNATIONAL ATOMIC ENERGY AGENCY The IAEA does not normally maintain stocks of reports in this series. However, microfiche copie f thesso e reportobtainee b n sca d from ClearinghousS I N I e International Atomic Energy Agency Wagramerstrasse 5 0 10 P.Ox Bo . A-1400 Vienna, Austria Orders should be accompanied by prepayment of Austrian Schillings 100, fore for e chequa th f m th IAEf m o n i o n i r eAo microfiche service coupons which may be ordered separately from the I MIS Clearinghouse. The originating Section of this publication in the IAEA was Physics Section International Atomic Energy Agency Wagramerstrasse 5 PO Box 100 A-1400 Vienna, Austria MANUAL FOR TROUBLESHOOTING AND UPGRADING OF NEUTRON GENERATORS IAEA, VIENNA, 1996 IAEA-TECDOC-913 ISSN 1011-4289 © IAEA, 1996 Printe IAEe th Austrin Ai y d b a November 1996 FOREWORD During the past 20-25 years the IAEA has provided many new laboratories in the developing world with simpl voltagw elo e accelerator productioe th r sfo f neutronno e th a svi well known 2H(d,n)3He and 3H(d,n)4He reactions. (These neutron generators were originally supplied mainly for purposes of neutron activation analysis). However, the operation of these machines can often be halted or compromised by a lack of special or short lifetime components. Serious problems can also arise when the original well-trained technical staff leav e laboratorieth e operatorw ne d whe e an s th ns have less experienc n acceleratoi e r technology. This manua s intendei l o assist d t operator troubleshootinn i s d upgradinan g f o g neutron generators directes i t I . d particularl operatoro yt techniciand san lesn si s experienced laboratorie thereford san descriptione eth principlee th f so techniqued san thesf so e machines e operatoar r oriented addition I . discussioa o n t e mai th nf n o characteristic f neutroo s n generators, detailed information is given on the function of particular commercial units, on common problems related to specific components of accelerators, and on methods of troubleshootin repaird gan . Detailed schemati circuid can t diagram providee ar s helo dt p operator developmene th n si improvemend an t generatorse th f o t . probleme Th s treate Manuae th n di l have been collected during several IAEA missions in developing countries. IAEe Th gratefuAs i . SztaricskaiT o t l performeo wh , majoe dth draftinre parth f o t g of the manuscript, and also to J. Csikai and S. Szegedi for their contribution to the drafting. The IAEA officer responsible for this publication was R.L. Walsh, Physics Section, Division of Physica Chemicad an l l Sciences. EDITORIAL NOTE In preparing this publication for press, staff of the IAEA have made up the pages from the original manuscripts submittedas authors.the viewsby The expressed necessarilynot do reflect those of the governments of the nominating Member States or of the nominating organizations. Throughout the text names of Member States are retained as they -were when the text was compiled. The use of particular designations of countries or territories does not imply any judgement by the publisher, the IAEA, as to the legal status of such countries or territories, of their authorities and institutions delimitation ofthe or theirof boundaries. The mention of names of specific companies productsor (whether indicatednot or registered)as does not imply any intention to infringe proprietary rights, nor should it be construed as an endorsement or recommendation on the part of the IAEA. The authors are responsible for having obtained the necessary permission for the IAEA to reproduce, translate or use material from sources already protected by copyrights. CONTENTS 1. INTRODUCTION ............................................................................9 . 2. PRINCIPLES OF OPERATION ............................................................ 11 3. DETERMINATION OF THE BEAM ENERGY ....................................... 23 4. TYPES OF NEUTRON GENERATORS ................................................. 26 4.1. Commerical neutron generators .....................................................8 2 . 4.2. Sealed tube neutron generators ....................................................... 34 4.3. Intense neutron generators ...........................................................8 3 . SOURCESN IO . 5 : OPERATION PRINCIPLES, MAINTENANCE AND TROUBLESHOOTING ............................................................... 43 5.1. High frequency ion sources ........................................................... 43 5.2. Extraction of ions from ion sources ................................................ 48 5.3. Maintenanc dischargs ga f eo e pyrex bottle .......................................1 5 . 5.4. High frequency oscillators ............................................................ 52 5.4.1. Troubleshooting of high frequency oscillators ........................... 55 5.5. Pennin sourcen gio s ...................................................................8 5 . 5.5.1. Troubleshooting of Penning ion sources .................................. 61 6. DEUTERIUM LEAKS ....................................................................... 63 6.1. The palladium leak ..................................................................... 63 thermomechanicae 6.2Th . needle lth lead ek an valv e ...............................5 6 . 6.2.1. The thermomechanical leak valve .......................................... 65 6.2.2. Maintenanc troubleshootind ean f thermomechanicago l leaks .......6 6 . 6.2.3. Needle valves .................................................................. 67 6.2.4. Maintenanc f needleo e valves ..............................................0 7 . 6.3. Calibratio f leano k valves s consumptioGa : n measurement sourcen io 3 7 f o s s 6.3.1. Measurement ..................................................................4 7 . DEUTERIU7 M ELECTROLYZERS .......................................................6 7 . e floa7.1Th t . regulator electrolyzer .....................................................0 8 . 8. REMOTE CONTROL OF THE HIGH VOLTAGE TERMINAL ................... 84 8.1. Mechanical control ....................................................................4 8 . 8.2. Electromechanical control ............................................................5 8 . 8.3. Insulation transformer control .......................................................6 8 . 8.4. Optical insulation control .............................................................. 88 8.5. Computer control ....................................................................... 88 9. VACUUM SYSTEMS OF NEUTRON GENERATORS .............................. 93 9.1. Important terms and units in vacuum technology ................................ 93 9.1.1. Terms ............................................................................ 93 9.1.2. Units ............................................................................. 99 9.2. Vacuum pumps .......................................................................... 100 9.2.1. Vacuum system base combinatioa n do f no oil diffusion and rotary pumps ............................................. 102 (a) The rotary vane pump .................................................. 102 diffusioe Th ) (b n pump .....................................................4 10 . (c) Combination of diffusion and rotary pump ......................... 106 9.2.2. Vacuum system based on Ti-ion getter pump ........................... Ill 9.2.3. Vacuum system base turbomoleculan do r pump .......................3 11 . 9.3. Pressure (vacuum) measurements .................................................... 115 9.3.1. Thermal conductivity gauges ...............................................5 11 . 9.3.2. lonization gauges .............................................................. 116 (a) Thermionic ionization gauges ......................................... 116 (b) Cold cathode or Penning ionization gauge .......................... 117 9.4. Pressure monitoring and leak detection ............................................ 118 9.4.1. Leak rate measurement ......................................................8 11 . 9.4.2. Pumping speed measurement ............................................... 119 9.4.3. Leak detection ................................................................3 12 . 10. BEAM ACCELERATION AND BEAM TRANSPORT SYSTEMS ................ 128 10.1. Electrostatic lens ...................................................................... 128 10.2. Unipotentia r Einzeo l l lens .........................................................9 12 . 10.3. Troubleshooting of electrostatic focus lenses .................................... 130 e acceleratio10.4Th . n tube ................................................................1 13 . 10.5. Troubleshooting of acceleration tubes ............................................. 134 11. PRINCIPLE BEAF SO M FILTERS ......................................................5 13 . 11.1. Electrostatic and magnetic beam deflection ...................................... 135 11.2. Troubleshootin f electrostatigo c deflectors ......................................7 13 . 11.3. Analyzing magnet f neutroo s n generators .......................................8 13 . 11.4. Vacuum chambers of deflecting magnets ......................................... 144 11.5. Problems with analyzing magnets .................................................5