0 0.1 0.2 0.3 0.4 0.5 0 30 60 90 Power (Watts) Grid Angle (Degree) Model Experimental Data A device to allow the remote manipulation of a high power microwave beam was constructed. The instrument functions by using polarization, reflecting a fraction of the microwave, as a function of the rotation angle, into a heat sink. Dynamic Nuclear Polarization Motorized Grid Rotator Above : the polarization control hardware. The polarizing grid acts as an adjustable beam splitter, allowing microwave power control. Lock Installation Microwave Beam Power Control and NMR Frequency Lock for Dynamic Nuclear Polariza>on Donovan Kelley, Bianca Trociewitz, William Brey, Thierry Dubroca Na:onal High Magne:c Field Laboratory, Tallahassee, FL NMR Frequency Lock Console Microwave Beam Power Control An NMR lock is an instrument that allows the correction of drift inherent to magnets over time. This correction capability permits significantly longer data averaging experiments. Acknowledgements This work is supported by the National Science Foundation through DMR-1157490 and CHE-1229170, and the State of Florida. I’d like to thank the CIRL, Jose Sanchez particularly, and Karol Bicket for this internship. References 1) Overhauser A., Phys. Rev. 92, 2 (1953) 2) Griffin R. et al., PCCP 12, 5737 (2010) 3) Nuclear Magnetic Resonance (NMR) ooSpectroscopy, McGraw Hill Education Moto r Polarizing Grid Conclusions Over the course of this internship and the construction of these two devices I have gained a great deal of understanding about the necessity of documentation and systematic trial and error. In the future the power controller could be configured to run automated experiments and the lock can be set up to run independently of its’ accompanying console. Lock Magnet Pre-Amp NMR Console Shim Control Right : the lock is set up in a test configuration. It is connected to the magnet via a pre-amp which amplifies the NMR signal. The “shim control” is used as a current amplifier to correct the magnetic field. Right : 16 NMR spectra of 1 H water over 12 hours. A clear drift of the field is visible over this short period of time Microwave power measured as a function of grid angle (diamonds). Calculated microwave power (solid line), based on a generalized Malus’ Law. R 2 Value = 0.998 Above : table of recorded recovery time after large field perturbation. Below : software user interface developed in LabVIEW TM . Overhauser 1 (Liquid) DNP Solid DNP 2 Microwave Source Photograph of Dynamic Nuclear Polarization instruments at the National High Magnetic Field Lab Lock Principle 1 2 3 4 5 Trial 1 2 3 4 5 Avg Time 50s 13s 47s 34s 45s 29s Field (a.u.) t = 0 hr t = 3 hr t = 6 hr t = 9 hr t = 12 hr Left : lock signal as a function of time (red is the real part; green is the imaginary part). Five perturbations were introduced. >me (s) Magne>c Field Schema:c adapted from reference (3)

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Page 1: Microwave Beam Power Control and NMR Frequency Lock for

0.1

0.2

0.3

0.4

0.5

0 30 60 90

Pow

er (W

atts

)

Grid Angle (Degree)

Model Experimental Data

A device to allow the remote manipulation of a high power microwave beam was constructed. The instrument functions by using polarization, reflecting a fraction of the microwave, as a function of the rotation angle, into a heat sink.

Dynamic Nuclear Polarization

Motorized Grid Rotator

Above: the polarization control hardware. The polarizing grid acts as an adjustable beam splitter, allowing microwave power control.

Lock Installation

MicrowaveBeamPowerControlandNMRFrequencyLockforDynamicNuclearPolariza>onDonovanKelley,BiancaTrociewitz,WilliamBrey,ThierryDubrocaNa:onalHighMagne:cFieldLaboratory,Tallahassee,FL

NMR Frequency Lock Console Microwave Beam Power Control An NMR lock is an instrument that allows the correction of drift inherent to magnets over time. This correction capability permits significantly longer data averaging experiments.

Acknowledgements This work is supported by the National Science Foundation through DMR-1157490 and CHE-1229170, and the State of Florida. I’d like to thank the CIRL, Jose Sanchez particularly, and Karol Bicket for this internship.

References 1) Overhauser A., Phys. Rev. 92, 2 (1953)

2) Griffin R. et al., PCCP 12, 5737 (2010)

3) Nuclear Magnetic Resonance (NMR)

ooSpectroscopy, McGraw Hill Education

Motor

Polarizing Grid

Conclusions Over the course of this internship and the construction of these two devices I have gained a great deal of understanding about the necessity of documentation and systematic trial and error. In the future the power controller could be configured to run automated experiments and the lock can be set up to run independently of its’ accompanying console.

Lock

Magnet

Pre-Amp

NMR Console

Shim Control

Right: the lock is set up in a test configuration. It is connected to the magnet via a pre-amp which amplifies the NMR signal. The “shim control” is used as a current amplifier to correct the magnetic field.

Right: 16 NMR spectra of 1H water over 12 hours. A clear drift of the field is visible over this short period of time

Microwave power measured as a function of grid angle (diamonds). Calculated microwave power (solid line), based on a generalized Malus’ Law.

R2 Value = 0.998

Above: table of recorded recovery time after large field perturbation.

Below: software user interface developed in LabVIEWTM.

Overhauser1 (Liquid) DNP Solid DNP2

Microwave Source

Photograph of Dynamic Nuclear Polarization instruments at the National High Magnetic Field Lab

Lock Principle 1 2 3 4 5

Trial 1 2 3 4 5 AvgTime 50s 13s 47s 34s 45s 29s

Field(a.u.)

t=0hr