A large aspect ratio (AR) leads to higher ion capacity in miniaturized ion trap mass spectrometers. The AR of an ion trap represents the ratio between an extended trapping dimension and the characteristic trapping dimension. In contrast to linear and rectilinear traps, changing the AR of a toroidal ion trap (TorIT) results in changes to the degree of curvature and shape of the trapping potential, and hence, on performance as a mass analyzer. SIMION simulations show that higher-order terms in the trapping potential vary strongly for small and moderate AR values (below ∼10), with the effects asymptotically flattening for larger AR values. Because of the asymmetry in electrode geometry, the trapping center does not coincide with the geometric center of the trap, and this displacement also varies with AR. For instance, in the asymmetric TorIT, the saddle point in the trapping potential and the geometric trap center differ from +0.6 to −0.4 mm depending on AR. Ion secular frequencies also change with the AR. Whereas ions in the simplified TorIT have stable trajectories for any value of AR, ions in the asymmetric TorIT become unstable at large AR values. Variations in high-order terms, the trapping center, and secular frequencies with AR are a unique feature of toroidal traps, and require significant changes in trap design and operation as the AR is changed.

大纵横比 (AR) 导致小型化离子阱质谱仪中的离子容量更高。离子阱的 AR 表示扩展捕获尺寸与特征捕获尺寸之间的比率。与线性和直线形阱相比，改变环形离子阱 (TorIT) 的 AR 会导致俘获电位的曲率和形状发生变化，从而导致作为质量分析器的性能发生变化。SIMION 模拟表明，对于小和中等 AR 值（低于 10），捕获电位中的高阶项变化很大，对于较大的 AR 值，效果逐渐变平。由于电极几何形状的不对称性，陷阱中心与陷阱的几何中心不重合，并且这种位移也随 AR 变化。例如，在非对称 TorIT 中，陷阱电位中的鞍点和几何陷阱中心从 +0.6 到 -0.4 mm 不等，具体取决于 AR。离子长期频率也随 AR 变化。尽管简化 TorIT 中的离子对于任何 AR 值都具有稳定的轨迹，但不对称 TorIT 中的离子在大 AR 值时变得不稳定。高阶项、陷阱中心和长期频率随 AR 的变化是环形陷阱的独特特征，并且随着 AR 的变化需要对陷阱设计和操作进行重大更改。