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Advances in rf Contactless Measurements in Pulsed Magnetic Field. Moaz Altarawneh FSU, NHMFL, LANL. Chuck Mielke LANL. James S. Brooks NHMFL, FSU. Neil Harrison, LANL. outline. The traditional Tunnel diode oscillator (TDO). Why we need a new rf method.
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Advances in rf Contactless Measurements in Pulsed Magnetic Field. MoazAltarawneh FSU, NHMFL, LANL. Chuck Mielke LANL. James S. Brooks NHMFL, FSU. Neil Harrison, LANL.
outline • The traditional Tunnel diode oscillator (TDO). • Why we need a new rf method. • Proximity Detector Oscillator (PDO).New. • Data obtained from the new method.
Traditional TDO experimental setup in dc field Oscillation condition At low temperature With small coils, circuit needs to be cooled down At room temperature C. T. VanDegrift. Rev. Sci. Instrum, 46(3):599, October 1975
Why we need a new rf method. Vinduced= 60 mV for 1 mm2area in 60T magnet Bias dependence of the TDO couples electrical noise to frequency. Extreme case of being kicked outside operating range by dB/dt.
The PDO Circuit The PDO operation is insensitive to voltages induced by pulsed magnetic fields due to its wide operating voltage range (5 to 35 volt) where TDO (~100mV). Less sensitive to the interferencefrom the pulsed field environment No voltage tuning is required (always Oscillating). High stability frequency during the pulse. M. M. Altarawneh, C. H. Mielke and J. S. Brooks. Rev. Sci. Instrum., 80, June 2009
PDO used for Studying superconductivity in Ba0.55K0.45Fe2As2 M. M. Altarawneh et al., Phy. Rev. Rapid Comm., 2008.
The PDO is used to perform rf measurements at very high magnetic fields 1K to 18K This data was collected for a High-temperature superconducting sample (HTS) in the 60 T long pulse magnet at LANL. • The PDO is used in 100T magnet too. • The PDO is used in 65T.
Thanks To • Dr. Stan Tozer and Mr. James A. Powell and electronic shop staff at NHMFL for reproducing a number of the PDO devices to be used at LANL and NHMFL –Tallahassee. • Thanks to Dr. Suchitra E. Sebastian for providing figures and data obtained from PDO. • This work was funded by LANL LDRD-DR200713. • My research is supported in part by NSF DMR-0602859.