Cycloidal mass analyzers are unique sector mass analyzers as they exhibit perfect double focusing, making them ideal for incorporating spatial aperture coding, which can increase the throughput of a mass analyzer without affecting the resolving power. However, the focusing properties of the cycloidal mass analyzer depend on the uniformity of the electric and magnetic fields. In this paper, finite element simulation and charged particle tracing were used to investigate the effect of field uniformity on imaging performance of a cycloidal mass analyzer. For the magnetic field, we evaluate a new permanent magnet geometry by comparing it to a traditional geometry. Results indicate that creating an aperture image in a cycloidal mass spectrometer with the same FWHM as the slit requires less than 1% variation in magnetic field strength along the ion trajectories. The new magnet design, called the opposed dipole magnet, has less than 1% field variation over an area approximately 62 × 65 mm; nearly twice the area available in a traditional design of similar size and weight. This allows ion imaging across larger detector arrays without loss of resolving power. In addition, we compare the aperture imaging quality of a traditionally used cycloidal mass spectrometer electric design with a new optimized design with improved field uniformity.

Open image in new window

摆线质量分析仪是独特的扇形质量分析仪，因为它们具有完美的双重聚焦特性，因此非常适合合并空间孔径编码，从而可以增加质量分析仪的通量而不影响分辨力。但是，摆线质量分析仪的聚焦特性取决于电场和磁场的均匀性。在本文中，有限元模拟和带电粒子跟踪用于研究场均匀性对摆线质量分析仪成像性能的影响。对于磁场，我们通过将其与传统几何体进行比较来评估新的永磁体几何体。结果表明，在具有与狭缝相同的FWHM的摆线质谱仪中创建孔径图像需要沿着离子轨迹的磁场强度变化小于1％。这种新的磁体设计称为对置偶极磁体，在大约62×65 mm的区域内磁场变化小于1％。是类似尺寸和重量的传统设计中可用面积的近两倍。这样可以在更大的检测器阵列上进行离子成像，而不会降低分辨能力。此外，我们将传统使用的摆线质谱仪电气设计的孔径成像质量与改进了场均匀性的新型优化设计进行了比较。是类似尺寸和重量的传统设计中可用面积的近两倍。这样可以在更大的检测器阵列上进行离子成像，而不会降低分辨能力。此外，我们将传统使用的摆线质谱仪电气设计的孔径成像质量与具有改善的场均匀性的新的优化设计进行了比较。是类似尺寸和重量的传统设计中可用面积的近两倍。这样可以在更大的检测器阵列上进行离子成像，而不会降低分辨能力。此外，我们将传统使用的摆线质谱仪电气设计的孔径成像质量与改进了场均匀性的新型优化设计进行了比较。

在新窗口中打开图像