Thermal demagnetization furnaces are widely used paleomagnetic facilities for progressive removal of naturally acquired magnetic remanence or the imparting of well-controlled laboratory magnetization. An ideal thermal demagnetizer should maintain “zero” magnetic field in the sample chamber during thermal treatments. However, magnetic field noises, including the residual magnetic fields of the construction material and the induced fields caused by the alternating current (AC) in the heating element are always present, which can contaminate the paleomagnetic results at the elevated temperatures or especially for the magnetically weak samples. Here, we designed a new structure of heating wire named “straight core solenoid” to develop a new demagnetization furnace with ultra-low magnetic field noise. Simulation and practical measurements show that the heating current magnetic field can be greatly reduced by using the new technology. Thermal demagnetization experiments demonstrate that the new demagnetizer can yield low noise results even for weakly magnetic samples.

中文翻译：

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一种用于高精度古地磁的超低磁场热退磁器

热退磁炉是一种广泛使用的古磁设备，用于逐步去除自然获得的剩磁或提供良好控制的实验室磁化。理想的热消磁器应在热处理期间在样品室中保持“零”磁场。然而，磁场噪声，包括建筑材料的剩余磁场和加热元件中由交流电 (AC) 引起的感应场始终存在，这会污染高温下的古地磁结果，特别是对于磁性弱样本。在这里，我们设计了一种名为“直芯螺线管”的新型电热丝结构，以开发出一种具有超低磁场噪声的新型退磁炉。仿真和实际测量表明，采用新技术可以大大降低加热电流磁场。热退磁实验表明，即使对于弱磁性样品，新型退磁器也能产生低噪声结果。