Fields in square helmholtz coils

Strattan, R. D.; Young, Frederick J.

doi:10.1007/bf02930884

Cited by 5 publications

(4 citation statements)

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“…A common coil, such as a solenoid, Helmholtz, saddle and birdcage coil, could be used to fabricate an NMR probe [22][23][24][25]. The solenoid coil possesses a higher excitation efficiency and better distribution homogeneity of the magnetic field [26]; therefore, it was selected to design the transmitting coil and the receiving coil of the orthogonal dual-coil installed in the NSS-NMR experimental system.…”

Section: The Coil Structure Optimizationmentioning

confidence: 99%

Non-Steady State NMR Effect and Application on Time-Varying Magnetic Field Measurement

Zeng

Jin

et al. 2022

Sensors

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The measurement of a time-varying magnetic field is different from a constant magnetic field, due to its field intensity variation with time. Usually, the time-varying magnetic field measurement converts the solution of the magnetic induction intensity into the calculation of the induced electromotive force (EMF); then, the magnetic induction intensity is obtained by the time integration of the EMF, but the process is vulnerable to external interference. In this paper, a non-steady state nuclear magnetic resonance (NSS-NMR) scheme for the measurement of a time-varying magnetic field is proposed. In a time-varying magnetic field environment, an RF excitation signal with a certain frequency bandwidth is applied to excite the nuclear spin system. The NSS-NMR signal, which varies with time in the frequency range corresponding to the frequency bandwidth of the RF excitation, could finally be obtained after a series of processing of the probe output signal. During the NSS-NMR experiment, an orthogonal dual-coil probe is adopted to synchronously generate the RF excitation and induce the probe output signal. Moreover, a directional coupler that utilized in the experiment outputs a reference signal from the coupling port for the subsequent signal processing. The experimental results show that the weak NSS-NMR signal is indeed observed. The longitudinal time-varying magnetic field ranges from 0.576 T to 0.582 T, which is inverted by the Larmor precession relationship, have been successfully detected based on the so-called NSS-NMR effect.

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Section: The Coil Structure Optimizationmentioning

confidence: 99%

Non-Steady State NMR Effect and Application on Time-Varying Magnetic Field Measurement

Zeng

Jin

et al. 2022

Sensors

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“…There are two types of steering coils at the cERL injector. Those coils that are designated as "ZHV1-5" are a set of two pairs of rectangular Helmholtz coils [49] placed in parallel to the direction of beam propagation (see Fig. 16).…”

Section: Steering Coil Effects On Beam Trajectorymentioning

confidence: 99%

“…Here the designations "ZH" and "ZV" correspond to the horizontal and the vertical steering, respectively. The magnetic fields of the pair of the rectangular coils are rather complicated [49][50][51][52]. Here, we apply the single loop approximation to describe the fields of the multiple turn coils.…”

Section: Steering Coil Effects On Beam Trajectorymentioning

confidence: 99%

New halo formation mechanism at the KEK compact energy recovery linac

Tanaka

Nakamura

Shimada

et al. 2018

Phys. Rev. Accel. Beams

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The beam halo mitigation is a very important challenge for reliable and safe operation of a high-energy machine. A systematic beam halo study was conducted at the KEK compact energy recovery linac (cERL) since non-negligible beam loss was observed in the recirculation loop during a common operation. We found that the beam loss can be avoided by making use of the collimation system. Beam halo measurements have demonstrated the presence of vertical beam halos at multiple locations in the beam line (except the region near the electron gun). Based on these observations, we made a conjecture that the transverse beam halo is attributed to the longitudinal bunch tail arising at the photocathode. The transfer of particles from the longitudinal space to a transverse halo may have been observed and studied in other machines, considering nonlinear effects as their causes. However, our study demonstrates a new unique halo formation mechanism, in which a transverse beam halo can be generated by a longitudinal bunch tail due to transverse rf kicks from the accelerating (monopole) fields of the radio-frequency cavities. This halo formation occurs when nonrelativistic particles enter the cavities with a transverse offset, even if neither nonlinear optics nor nonlinear beam effects are present. A careful realignment of the injector system will mitigate the present halo. Another possible cure is to reduce the bunch tails by changing the photocathode material from the present GaAs to a multi-alkali that is known to have a shorter longitudinal tail.

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“…The computation of the magnetic field for coils with geometries other than the circular could be cumbersome because of the vectorial nature of the Biot-Savart law [17]. Different designs inspired by Helmholtz coils have been implemented since their creation in an attempt to optimize their main characteristics, such as their region of homogeneity and the simplicity of their manufacture [9][10][11][12][13][14][15][16]. In this work, we consider an extension of the classical Helmholtz coils when the wires are shaped like an ellipse.…”

Section: Introductionmentioning

confidence: 99%

Elliptic Helmholtz coil

Romero-Abad,

Reyes-Portales,

La Rosa-Navarro

et al. 2022

Rev. Bras. Ensino Fís.

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Using the Biot-Savart law, we compute the magnetic field produced by steady currents that circulate in the same direction through two parallel ellipse-shaped loops. The calculation was performed along the axis that passes across the center of the ellipses. Then, we show that this arrangement produces a nearly uniform magnetic field for particular values of the semi-axis of the ellipse and the separation distance between the loops. This outcome is obtained as a consequence of numerically solving the second derivative condition. In addition, we show that, for the values reached, the elliptical Helmholtz coil produces results that are compatible with those of the classical circular Helmholtz coil. Finally, we show how the uniformity of the magnetic field varies for regions off the axis of the ellipses. The target readers of the paper are students pursuing physics at the intermediate undergraduate level.

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Fields in square helmholtz coils

Cited by 5 publications

References 0 publications

Non-Steady State NMR Effect and Application on Time-Varying Magnetic Field Measurement

Non-Steady State NMR Effect and Application on Time-Varying Magnetic Field Measurement

New halo formation mechanism at the KEK compact energy recovery linac

Elliptic Helmholtz coil

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