MAGNET SYSTEM FOR W BAND EPR SPECTROMETER

伊利诺伊州电子顺磁共振研究所的W波段(95 GHz)电子顺磁共振波谱仪 该中心被设计为一台多功能科学仪器。这个 光谱仪的能力已经通过增加一个快速的 磁场扫描系统(最大1000G扫描，最小为1 秒)和一个专门设计的变温低温恒温器 研究(2-300K)真空密闭微波窗口。禁食 扫描系统采用了室温水冷螺线管和 改装Techron(Techron，IN)电源。扫描系统 采用14位分辨率的数字扫描。此外，一个新的 设计了一种用于扫描磁场的水冷线圈，并对其性能进行了测试 由伊利诺伊大学制造。新线圈的产量为18% 在相同电流下更大的磁场扫描比 牛津原创设计。以获得高精度、可重现的扫描 围绕中心场，我们修改了原来的扫描线圈 由牛津大学提供。首先，我们更换了原来的扫描线圈 我们自己的设计具有+/-600高斯的扫描范围，而不是 最初的+/-500高斯。第二，因为强大的权力， 高稳定的两极电源很难获得，我们 在原始版本上添加了Danfysik Ultrastab电流传感器 牛津大学提供的功放。Danfysik传感器运行在 零磁通原理，实现电流测量和调节 与它们的固有温度没有欧姆连接 大电流下的稳定问题。16位D/A转换器允许 以15毫克的步幅扫地。测量的可重置性 优于100A，稳定性优于10ppm。在.期间 在本赠款年度，扫描线圈进行了两次重新设计以 提高隔离度和稳定性。W频段系统可访问 提供给其他人用于协作或服务。发展和 改进这一系统是一项正在进行的项目。

The W-band (95 GHz) EPR spectrometer at Illinois EPR Research Center was designed as a multi-purpose scientific instrument. The capabilities of the spectrometer have been extended by adding a fast magnetic field sweep system (maximum 1000 G sweep in a minimum of 1 sec.) and a specially designed cryostat for variable temperature studies (2-300 K) with a vacuum-tight microwave window. The fast sweep system employs a room-temperature water-cooled solenoid and a modified Techron (Techron, IN) power supply. The sweep system features a digital scan with 14 bit resolution. In addition, a new water-cooled coil for scanning the magnetic field was designed and manufactured at the University of Illinois. The new coil produces 18% larger scans of magnetic field at the same current than does the original Oxford design. To obtain high-precision, reproducible sweeps around the center field, we have modified the original sweep coil supplied by Oxford. First, we have replaced the original sweep coil wi th our own design having a sweep range of +/- 600 Gauss, instead of the original +/- 500 Gauss. Second, because high-power, high-stability bipolar power supplies are difficult to obtain, we added a Danfysik Ultrastab current transducer onto the original amplifier supplied by Oxford. The Danfysik transducer operates on the zero flux principle and enables current measurement and regulation without an ohmic connection with their inherent temperature stabilization problem at high current. A 16-bit D/A converter allows sweeping the field in steps as fine as 15 mG. Measured resettability is better than 100 A and the stability is better than 10 ppm. During the current grant year the scanning coil was twice redesigned to improve the isolation and stability. The W-band system is accessible to others for collaborative or service use. Development and improvement of this system is an ongoing project.