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Introduction to the Pulsed Field Facility

NHMFL-PFF. Introduction to the Pulsed Field Facility. Chuck Mielke. Overview. What is a Pulsed Magnet? Why Pulsed Magnets? What are the limitations? Thermal limits Mechanical limits Our Pulsed Field Facility Extreme Fields. What is a pulsed magnet?. Transient Field Electromagnet

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Introduction to the Pulsed Field Facility

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  1. NHMFL-PFF Introduction to the Pulsed Field Facility Chuck Mielke

  2. Overview • What is a Pulsed Magnet? • Why Pulsed Magnets? • What are the limitations? • Thermal limits • Mechanical limits • Our Pulsed Field Facility • Extreme Fields

  3. What is a pulsed magnet? • Transient Field Electromagnet • Research applications • Most run in the single shot mode • Our high field solenoids are mechanically reinforced

  4. Why Pulsed Magnets? Electrical current (moving charge) creates a magnetic field Andre-marie Ampere 1820-1827: Discovered that electricity in motion can produce magnetism Ampere’s law

  5. Some “Practical” numbers… 10 Tesla = 1.2e-6 NA-2x 100 turns x 8,000 Amps / 0.1 m But wait… is 8,000 amps practical? Joule’s Law = 64 MA2x 0.01 Ωx 60 s = 38 MJ DT = Q/mCp = 38 MJ / (0.15 kg * 385 J/kgK) = 664,000 K

  6. Some “Practical” numbers… 60 s / 2000 = 0.030 s 38 MJ/2000 = 19.2 kJ 10 Tesla = 1.2e-6 x 100 turns x 8,000 Amps / 0.1 m But wait… is 8,000 amps practical? Joule’s Law = 64 MA2x 0.01 Ωx 0.03 s = 19.2 k J DT = Q/mCp = 19.2 kJ / (0.15 kg * 385 J/kgK) = 332 K

  7. Mechanical Limits… Strong electromagnets generate BIG forces Pressure under water: @ 12 feet (ears) 6 psi @ 2,000 feet (submarine) 1000 psi @12,000 feet (ocean floor) 6000 psi Pressure inside powerful electromagnets: @ 80 tesla(pulsed magnet) 200,000 psi (which equals 130 kg per square millimeter) More pressure than most materials can handle!

  8. The destiny of every pulsed magnet: failure

  9. Before and after 0.6 MJ of energy 60 Tesla ‘short pulse’ • ~6 milli-seconds to peak field • Life-time of ~500 full field shots. • ~30 minutes between full field shots. 10 cm

  10. Pulsed Magnets Adiabatic joule heating during the pulse and subsequently left tocool. Less power consumption, less expensive cooling infrastructure, but requires fast measurements Pulse defined by: C,V,L,Rmag,Rcrowbar CuNb, CuAg, etc. It is all about Managing the Compromises

  11. Technical Area 35

  12. Pulsed Magnets of the NHMFL • Cell 1 (50 T Mid Pulse, 15 mm, 300 msec) • Cell 2 (65 T short pulse, 24mm, 25 msec) • Cell 3 (65 T short pulse, 15 mm, 25 msec) • Cell 4 (65 T short pulse, 15 mm, 35 msec) • 60T Long Pulse, 2500 ms, 32 mm,100 msec flattop • 100T Multi Shot, 2500 ms,15mm, 20 msec above 40T • Operational to 85 T • 300T Single Turn, 10 mm, 0.006 ms • Operational to 240 T (routine to 170 T)

  13. Pulsed Magnet Waveforms

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