Implementation of specific-heat and NMR experiments in the 1500 ms long-pulse magnet at the Hochfeld-Magnetlabor Dresden

Abstract

We report on the design and successful testing (up to 55 T) of a 60 T long-pulse (LP) magnet with a pulse duration of 1500 ms at the Hochfeld-Magnetlabor Dresden. This magnet has the capability of producing magnetic fields with time and homogeneity characteristics suitable to host specific-heat and nuclear magnetic resonance (NMR) experiments. We describe the development of a specific-heat probe for this magnet, which uses the quasi-adiabatic heat-pulse method and enables magnetocaloric-effect measurements. Furthermore, we report the implementation of a NMR setup, consisting of home-built probe and spectrometer. Both experimental devices were tested successfully in the LP magnet up to 31 and 44 T, respectively.

Generation of flat-top pulsed magnetic fields with feedback control approach

“…With the latter, a combination of the present feedback system with a pulsed magnet having a long time duration, such as the 1.5-s long-pulse magnet at HLD [2], might be the most suitable to obtain a long-duration FTPMF. To check how the present feedback system works with small dH/dt pulsed fields, we reduce the field strength generated by the 60-T pulsed magnet, and the results are presented in Because the reduction in dH/dt leads to a longer duration for FTPMF, we expect a long pulsed magnet with the present feedback system to be a powerful way to produce…”

“…[6] In contrast, the field profile of capacitor-bank-driven pulsed magnetic fields is perfectly smooth and its field strength can surpass 60 T. However, this type of pulsed field does not strictly have a flat region in the field profile; specific experiments that use such FTPMFs are difficult to perform. Even at the High Field Laboratory in Dresden (HLD), which generates the longest pulsed duration of 1.5 s for a capacitor-bank-driven pulsed magnetic field, the field strength changes by 1 T over intervals of 70 ms [2]. To overcome this issue, a modification of the pulsed field profile has been investigated by dividing the capacitor bank modules into two groups: one driving the current for the pulsed magnet and the other suppressing the current around field maxima, thereby leveling the top of the field pulse [7].…”

Irreversible Heating Measurement with Microsecond Pulse Magnet: Example of the α–θ Phase Transition of Solid Oxygen

“…[3][4][5][6][7][8][9] Recently, MCE measurements have been combined with pulse magnetic fields and applied to various research in physics at high fields. [10][11][12][13][14][15] In the adiabatic MCE, the temperature change ∆T can be divided into reversible and irreversible terms [16][17][18] as ∆T = ∆T rev + ∆T irr .…”

“…The surplus energy can be obtained from µ 0 BdM, which mainly results in the heating as hysteresis loss. 20,21 In previous studies, [3][4][5][6][7][8][9][10][11][12][13][14][15] the authors were mainly interested in ∆T rev , which reveals isentropes in the magnetic fieldtemperature (B-T ) plane. The discontinuity in the isentropes indicates the phase boundary in the B-T phase diagram.…”

Broadband Continuous Nuclear Magnetic Resonance Signal in a Pulsed Magnetic Field: Numerical Solutions of Bloch Equations under Radio Frequency Irradiation

“…They observed the Fourier transform spectra of Cu metal ( 63 Cu) at 33 T using a radio frequency (RF) pulse of 0.5 ls duration to excite the free induction decay (FID) near the peak of the pulsed field. In the following years, pulsed NMR experiments on other nuclei and in higher fields [4][5][6][7][8][9] were published. These works show that performing NMR in pulsed magnetic fields is indeed possible.…”