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Review of Instrumentation. Instrumentation Staff. William Brey Group Leader Peter Gor’kov Solid State and Imaging Probes Kiran Shetty Series Connected Hybrid (SCH) Jason Kitchen Mechanical Engineer (started May 09) Richard Desilets Machinist. Projects. I maging (presented by Sam Grant)
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Review of Instrumentation Instrumentation Staff William Brey Group Leader Peter Gor’kov Solid State and Imaging Probes Kiran Shetty Series Connected Hybrid (SCH) Jason Kitchen Mechanical Engineer (started May 09) Richard Desilets Machinist Projects • Imaging (presented by Sam Grant) • Low E Probe Development • VTMAS Capability • Low Probe Development • Shims and Field Regulation for SCH • Superconductive RF Probe Development
Low-E Probe Development at the NHMFL Solenoid 5 turns Low-E ~10X ∆T (°C) 8 turns 100 mM NaCl 20 mM TmDOTP @ 600 MHz Time-averaged power B12 in RF coil (kHz2) • Independent loop gap resonator for 1H channel reduces electric field, sample heating • Double-tuned solenoid optimized for lower frequency (has more turns) (horizontal axis values include duty cycle) • Highlights and Milestones: • Static probes developed for flat (270 L), and static bicelle (5 and 6.6 mm) samples for 600 and 900. Users include Cross, Veglia, Cotten, Ramamoorthy, Lorigan. • MAS probe developed for 4 mm / 750 MHz (Long). • Bruker adapted technology for “Efree” probe; sponsored postdoc at MagLab for 2 years (2007-2009).
Triple Resonance Low-E Probe Development • Solenoid uses Cross-Waugh network with lumped element traps, balanced on both X&Y channels. • Plug in and screw down inductors and capacitors allow rapid retuning. • Revolution NMR stators have been optimized to accommodate long low-E inserts. • Prototype MAS probe for 600 MHz. Follow on probes will include 900 MAS, 600/900 static, 750 MAS. Supported by User Collaboration Grant “Instrumentation and Techniques to Use 14N NMR to Probe the Structure of Biomolecules,” Brey, Gan Gor’kov, Hung 14N/13C/1H Low-E MAS Probe, 3.2 mm 600 MHz
Balanced Tuning in Narrow Bore 830 MHz Magnet 7 mm and 4 mm MAS probes • Balanced tuning reduces voltages, suppresses arcing, allows doubling of B1. • Insertable capacitors allow practical balanced circuit in 32 mm bore of 830 magnet (see photo). • For MQMAS (4 mm rotor), multiple quantum excitation efficiency and S/N ~ γB1 thereby doubling the S/N for the balanced version. • 7 mm probe (shown at right) always needed more B1. unbalanced balanced Z. Gan, P.L. Gor'kov, W.W. Brey, P.J. Sideris, and C.P. Grey, J. Magn. Reson. 200, 2-5 (2009).
Improved VT MAS Capability for 900 Routine Spinning to Below -150 C • LN2 system cools probe quickly from room temp to -150 C (123 K) with N2 flow of 1200 L/hr (42 scfh) • Minimal icing allows safe, reliable operation • Auto refill controller for continuous operation • Refills of 45 L lab cryostat (from 40% to 60%) occur about every 3 hours (9 L transfer per refill). • Tied for Best Senior Project of 2009 in FAMU-FSU Mechanical Engineering Department Team members (L-R): Jason Kitchen, Rebecca Altman, Jessica Vanterpool, Zachary Stevenson
How to get temperature stability during refills from a Doty cooling system • Shield the precooling coils from venting gas. Boiloff increases during fills, reducing outlet gas temperature. The increase in cryogen consumption was only ~10%. • Pressurize the supply dewar only during transfers. The LN2 in a self-pressurized cryostat at 22 psig is at 86 K, not 77 K, which changes the bath temperature during a transfer. • Adjust the PID coefficients for the VT controller. The Bruker “edte” autotune gives very low values of “P” that compromises the response. Insulation on precooling coils Refill fluctuations reduced from ~3 C to 0.3 C User/Collaborators: Riqiang Fu and Naresh Dalal Original Modified
36 T in 2013: the Series Connected Hybrid • We are developing: • Field regulation (Schiano collaboration) • Active shims (MS&T collaboration) • RF Probes • Proposal to NSF’s “MRI-R2” call for 1.6 GHz console was submitted August 2009. The SCH will have less field noise and better homogeneity (after correction) than other powered magnets. Supported by NSF through DMR-0603042
Resistive Shims for SCH Field Correction of Keck 25 T Magnet at 7 T Difference Mapping Allows Correction of Fluctuating Fields High current power supplies 50 ppm/150 A water cooled 6-term shim coil Painter, T.A.; Bird, M.D.; Bole, S.T.; Trowell, A.J.; Shetty, K.K. and Brey, W.W., Resistive Shims for High-Field Resistive and Hybrid Magnets,IEEE Trans. Appl. Supercond., 18 (2), 579-582 (2008)
Field Regulation for SCH Keck Noise Spectra Correction coil Pick up coil RF Probe • Collaboration with Prof. Jeffrey Schiano at Penn State. • Temperature-regulated preamplifier has reduced drift. Integrating Preamp Digital Controller Current Driver
NHMFL/Bruker 1 mm HTS Probe • Total mass sensitivity >3x that of the best commercial micro-solenoid! • Meets standard requirements for • Non-spinning lineshape (50/.55/.11%): 0.88 / 13.9 / 20.9 Hz • Pulse lengths:1H: 9.5 s, 13C: 15 s, 15N: 48 s 12 mm Funded by NIH Now part of NHMFL User Program • On-line since September, 2005 • Triple-resonance (1H, 13C, 15N, 2H) • 600 MHz • Minimum sample volume: 7.5 L • Active sample volume: 6.3 L Brey, W.W.; Edison, A.S.; Nast, R.; Rocca, J.; Saikat Saha, S. and Withers, R.S., Design, Construction and Validation of a 1 mm Triple Resonance High-Temperature Superconducting Probe for NMR,J. Magn. Reson., 179 (2), 290-293 (2006)
High Temperature Superconductor (HTS) Probe Technology Vacuum wall Spiral for low freqs Lattice-matched substrate 1H Epitaxial Y1Ba2Cu3O7-(YBCO) Single-sided Resonators Helmholtz Pair • Technology Limitations: • Single frequency resonators • Single sided devices only • Flat substrates only HTS coil resistance less than 1/10 of conventional cryoprobes!
R01 Funded July 2009 to Develop 1.5 mm Dual Sensitive13C/1H Superconductive Cryoprobe Mag Lab NMR User Program Edison (PI, NMR) Brey (RF Design) Mag Lab Applied Superconductivity Center David Larbalestier Varian, Inc. Rich Withers Rob Nast Tom DeSwiet • Collaborative materials and RF development toward more compact, sensitive, efficient and homogeneous triple resonance coil sets. • Coil/sample optimization to reduce loading and increase sensitivity. • Magnet Lab and Varian matching funds to support purchase of Varian console.
Instrumentation Highlights 2009 • Jason Kitchen hired to support user programs. • VT MAS functioning to -150 C on 900 UWB stable to 0.3 C • Balanced low- probes for 830 narrow bore double B1. • HTS probe development funded by Edison R01 • SCH Console application through MRI-R2 • Difference map of Keck powered magnet to 1 ppm