Investigation of losses for MKI FVC system TEABTEC

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

Contents • • • Introduction Objectives Measurements Tests and Results PCB Design Conclusion

Self introduction • • • 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 Electronics and programming Hiking Skiing Refuge du Parmelan 10/25/2020 4 4

Introduction System overview Thyratron tank filled with dielectric oil Plastic Optical Fibre Faraday cage 25 m 120 cm Emitter Bias board Receiver FVC PLC system • Grid voltage reading Thyratron Grids SCADA • Data logging • Trending System is designed for : • • • Thyratron health check Premature ageing detection Thyratron readiness Preventive maintenance Additional MKI protection (Interlocks) FVC: Frequency to Voltage Converter 10/25/2020 5

Introduction Control racks Thyratron • MKI injection system at point 2 and point 8 MS Tank ≈ 25 DS Tank met ers • • • 8 thyratrons HV switches 8 Plastic fibre links Maximum length around 25 meters LHC MKI injection system at point 2 Th D PF N Th M FVC Th M <25 m PF N Th D Th M Th D PF N <25 m ≥ 25 m LHC MKI injection system topology at point 2 10/25/2020 6

Introduction Optical emitter CX 1171 thyratron schematic diagram Thyratron bias board • • • High voltage thyratron gas tube Grid voltage to frequency converter Power supply for thyratron heaters/reservoirs Supply for thyratron grid voltages 10/25/2020 7

Introduction • Trend from Win. CC SCADA system of injection kicker Thyratron grid voltages acquisition at point 2 Problems: • 3 measurements are faulty • 1 measurement on the limit (noisy) 10/25/2020 8

Objectives Faraday cage Emitter Bias board 25/50/100 m 120 cm Receiver FVC Dummy Load Oscilloscope Optokon Tank optical fibre connector: POF: • • • MKI FVC test bench synoptic Signal losses investigation Repeater box design Alternative solutions 10/25/2020 9

Optical budget calculation Attenuation/Length 10 9 Attenuation (d. B) 8 7 6 Fibre 1 m 5 Fibre 3 m 4 Fibre 25 m 3 Fibre 50 m 2 1 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 Distance (m) PT(min): Minimum coupled power of transmitter (d. Bm) PRL, min: Sensitivity of the receiver (d. Bm) Il: Sum of insertion loss of feedthroughs (d. B) OPM: Optical power margin, which accounts for LED degradation, supply voltage variation, etc. (d. B) α(max): Maximum attenuation of fibre (d. B/m) Theoretical length higher than the actual configuration 10/25/2020 10

Measurements Distance/attenuation 5 4. 5 ↕∆d 4 attenuation (d. B) 3. 5 Gap between the emitter coupling and the fibre 3 2. 5 R 2 = 0. 998 2 1. 5 1 0. 5 0 0 0. 05 0. 15 0. 25 0. 3 distance (cm) Attenuation (d. B) Optical power (µW) 0. 35 0. 4 Avago SFH 756 V transmitter Expon. (Optical power (µW)) Fibre Distance vs attenuation chart 10/25/2020 11

Measurements taken at point 2 (UA 23) Optical power measured (µW) D MKI. D M 4, 2 • • D MKI. C M FVC 3, 6 M MKI. B D 3, 4 M MKI. A D 4, 6 Optokon instrument used to measure optical power in µW The optical power was found to be reduced by a factor of 7 to 9 times less than expected • Hypothetically, losses could be localised inside thyratron tank OPTOKON OFT 820 -POF 10/25/2020 12

Additional measurements from other ABT kicker thyratrons Fibre Optic read back for Thyratron Bias Boards Hrs of operation Generation of Bias Board MKI Switch Name Optical Power Output (µW) Mumbles 72 150 New MKP Maddox 4 43 175 New MKP Dan 6 51 284 New MKP Dara 10 20 9794 New MKP Dabi 1 23 10410 New MKP Daniel 21 12745 New MKP Dita 11 11 14000 New MKP Danton 9 8. 1 23760 New MKI Point 2 3. 4375 40320 New System 10/25/2020 13

Additional measurements from other ABT kicker thyratrons MKP Optical power/Running hours 55 50 45 Optical power (μW) 40 35 30 25 20 R 2 = 0. 95 15 10 5 0 100000 Running hours 10/25/2020 14

Splicing and polishing investigations • Usage of USB microscope for surface magnification • • Cutting tool without polishing Fibre polishing and optimisation Termination surface spliced by the tool (Zoom x 210) Difference: 0. 75 d. B RENNSTEIG 8000 0001 3 Termination surface polished (Zoom x 210) 10/25/2020 15

Alternative Fibre • Advantages: • Step Index HCS usable at 650 and 850 nm with the actual emitter/receiver • Glass optical fibre has lower attenuation and greater BW than POF (≤ 6 d. B/km) at 850 nm • Superior Macro bending performance http: //www. ieee 802. org/3/NGAUTO/public/jan 17/whelan_3 NGAUTO_01 b_0117. pdf 10/25/2020 16

Repeater Design • As intermediary solution adding a repeater between thyratron optical output and acquisition system Tank filled with oil Faraday cage Emitter Bias board 120 cm ≥ 1 m Repeater ≥ 25 m Receiver FVC Load 10/25/2020 17

Conclusion • Repeaters implemented • Possible components replacement with new versions for future installations • Long-term test of the transmitter in oil (cold and warm oil) Avago SFH 756 V Not Recommended for New Design 10/25/2020 Avago AFBR-X 528 CZ 18

Acknowledgments 10/25/2020 19

Thank you for listening 10/25/2020 20

VFC electrical schematic 10/25/2020 21