AUSTRALIAN NATIONAL UNIVERSITY NUCLEAR PHYSICS DEPARTMENT  14 UD McSNICS ION SOURCE EARTH SAFETY  GASNICS CORONA DISCHARGING ISSUES Gareth Crook

BACKGROUND ISSUES  PREVENT INJURY OR DEATH FROM HIGH VOLTAGE (150KV) SYSTEMS  PROVIDE MECHANICAL RELIABILITY  WILL A BACK-UP SYSTEM BE REQUIRED?  CAN THIS SYSTEM BE INSTALLED ON OTHER HIGH VOLTAGE EQUIPMENT?  WHO WILL BE USING ACCESSING THESE HV ENCLOSURES?

THE ENVIRONMENT WE ARE LOOKING TO IMPROVE SAFETY OF

EXISTING DEFICIENCIES IN PROTECTION ACRYLIC SHEET RATHER THAN STEEL MESH POSSIBLE HIGH VOLTAGE ACCESS POINTS 150kV TO DECK

THE GLASSMAN 200kV 2.0mA DC POWER SUPPLY

EARTHED MESH ENCLOSURE SNICSII IMPROVED HV ACCESS POINTS EARTHING STRAPS

AUTOMATIC EARTHING ROD EARTH ROD DELRIN ROLLER BALL BEARING PIVOT COUNTERWEIGHT TRIGGER ARM

WHY??  A SHOCK FROM THIS POWER SOURCE IS POSSIBLY FATAL!  THESE ENCLOSURES ARE ACCESSED AT TIMES BY STUDENTS AND NEW TECHNICAL STAFF – WHILE THIS IS DONE WITH MANY PRECAUTIONS IN PLACE THERE IS STILL A CHANCE THAT EXPERIENCED USERS COULD FORGET TO PLACE MANUAL GROUND HOOK.  THIS SYSTEM CAN BE FITTED WITH A INTERLOCK SWITCH AS A FEED BACK SYSTEM TO OUR SAFETY CONTROLS.  WHILE THIS TYPE OF GROUNDING ARRANGEMENT IS RELIABLE IT WILL NEVER REPLACE THE USE OF OUR MANUAL GROUNDING HOOKS IN OUR SAFETY PROTOCOL.

OPERATION

DAMPENED CONTACT

MANUAL BACK-UP

CORONA DISCHARGE FROM SNICSII ION SOURCE

REASONS FOR UN-STABLE CHARGE LOSS FROM HV DECK  ENVIRONMENTAL EFFECTS WITHIN THE TOWER STRUCTURE  DESIGN ISSUES RELATED TO INCREASED DECK CHARGING FROM 100kV TO 150kV  CLEANLINESS OF INSULATING MATERIALS  CONDUCTIVITY OF PROCESSED COOLING WATER  CONDITION OF POWER SUPPLY CONTROL AND READ-BACK SYSTEM.

ISSUES BY DESIGN 530mm SHARP EDGES ON CONDUCIVE MATERIALS METAL PROJECTIONS EXISTING CORONA DAMAGE

LATER DESIGN IMPROVEMENTS FLAT PLANES AT DECK POTENTIAL SHEILDING IRREGULARLY SHAPED INTERNAL SURFACES THAT COULD PRODUCE CONCENTRATED FIELDS -LARGE RADIUS FRAMING TO DISTRIBUTE ELECTRIC FIELDS -BARE STAINLESS STEEL FRAME MATERIAL

SOME BASIC IMPROVEMENTS ALUMINIUM PANELS FITTED TO DISTRIBUTE FIELD RE-DRESSING OF DECK EDGES -NEW COOLING LINES FITTED -COOLING WATER TESTED ARCRYLIC BASE CLEANED

WHATS THE DIFF?  CONTROL = 150kV  DRESSING OF SHARP EDGES = 150kV  REMOVAL OF COOLING LINES = 150kV  INSTALLATION OF AL PANELS = 150kV  TEST AFTER 3 WEEK PERIOD = 150kV (THIS CHANGE IS MOST PROBABLY DUE TO ATMOSPHERIC CHANGES IN LAB)

FUTURE PLANS  REPLACEMENT OF SOME FRAME SECTIONS OF GASNICSII IN-LINE WITH OUR McSNICS DESIGN  DRESSING/RADIUSING OF ALL SHARP PROJECTIONS POSSIBLE ON SOURCE DECK AND  INCREASED MONITORING OF COOLING WATER SYSTEMS FOR CONDUCTIVITY AND PH LEVELS  IMPROVED CLEANING REGIME FOR INSULATING COMPONENTS AND SOURCE DECK SURFACES.  IMPROVED EARTHING OF SOURCE CAGE