Investigation of losses for MKI FVC system

Investigation of losses for MKI FVC system TE-ABT-EC

Contents Introduction Objectives Measurements Tests and Results PCB Design Conclusion

Self introduction • Electronics and programming • Hiking • Skiing • BTEC National Diploma • Higher National Diploma • Bachelor of Engineering • Master’s Degree in Engineering • Summer job at the town Hall of Seynod • Technician at Pfeiffer Vacuum Annecy • Internship at CERN Refuge du Parmelan 4

Receiver FVC Thyratron tank filled with dielectric oil Faraday cage Emitter Bias board 25m Introduction 120cm Thyratron Grids System overview Plastic Optical Fibre • PLC system • Grid voltage reading • SCADA • Data logging • Trending FVC: Frequency to Voltage Converter System is designed for : • Thyratron health check • Premature ageing detection • Thyratron readiness • Preventive maintenance • Additional MKI protection (Interlocks)

FVC Introduction Th D PFN PFN Th M Th M Th D Th M Th M PFN PFN Th D Th D <25m <25m • MKI injection system at point 2 and point 8 • 8 thyratrons HV switches • 8 Plastic fibre links • Maximum length around 25 meters ≥25m ≥ 25m Thyratron Control racks MS Tank ≈ 25 meters DS Tank LHC MKI injection system at point 2 LHC MKI injection system topology at point 2

Introduction CX1171 thyratron schematic diagram Optical emitter High voltage thyratron gas tube • Grid voltage to frequency converter • Power supply for thyratron heaters/reservoirs • Supply for thyratron grid voltages Thyratron bias board

Introduction • Trend from WinCC SCADA system of injection kicker • Problems: • 3 measurements are faulty • 1 measurement on the limit (noisy) Thyratron grid voltages acquisition at point 2

Faraday cage Receiver FVC Emitter Bias board Oscilloscope 25/50/100m 120cm Objectives Dummy Load Oscilloscope Optokon Thyratron bias board FVC Dummy Load Tank optical fibreconnector: POF: MKI FVC test bench synoptic Signal losses investigation Repeater box design Alternative solutions

Optical budget calculation PT(min): Minimum coupled power of transmitter (dBm) PRL, min: Sensitivity of the receiver (dBm) Il: Sum of insertion loss of feed-throughs (dB) OPM: Optical power margin, which accounts for LED degradation, supply voltage variation, etc.(dB) α(max): Maximum attenuation of fibre (dB/m) Theoretical length higher than the actual configuration

Measurements ↕∆d Gap between the emitter coupling and the fibre Fibre Distance vs attenuation chart Avago SFH756V transmitter

Measurements taken at point 2 (UA23) • Optokon instrument used to measure optical power in µW • The optical power was found to be reduced by a factor of 7 to 9 timesless than expected • Hypothetically, losses could be localised inside the thyratron tank OPTOKON OFT 820-POF

Additional measurements from other ABT kicker thyratrons

Splicing and polishing investigations • Usage of USB microscope for surface magnification • Cutting tool without polishing • Fibre polishing and optimisation Termination surface finely polished (Zoom x210) Difference: 0.75 dB Termination surface spliced by the tool (Zoom x210) RENNSTEIG 8000 0001 3 Termination surface polished (Zoom x210)

Alternative Fibre Advantages: • Step Index HCS usable at 650 and 850nm with the actual emitter/receiver • Glass optical fibre has lower attenuation and greater BW than POF (≤6dB/km) at 850nm • Superior Macro bending performance http://www.ieee802.org/3/NGAUTO/public/jan17/whelan_3NGAUTO_01b_0117.pdf • Improvement of optical fibre quality (200μm HCS Fibre)

Tank filled with oil Receiver FVC Faraday cage Emitter Bias board ≥25m Repeater Design 120cm Load ≥ 1m • As intermediary solution adding a repeater between thyratron optical output and acquisition system Repeater

Conclusion Avago SFH756V Not Recommended for New Design Avago AFBR-X528CZ Repeaters implemented Possible components replacement with new versions for future installations Long-term test of the transmitter in oil (cold and warm oil)

Acknowledgments

Thank you for listening

VFC electrical schematic

Investigation of losses for MKI FVC system