Advanced Composition Explorer (ACE) Solar Wind Ion Composition Spectrometer (SWICS) and Solar Wind Ion Mass Spectrometer (SWIMS) Level 2 Data

The Solar Wind Ion Composition Spectrometer (SWICS) and the Solar Wind
Ion Mass Spectrometer (SWIMS) on ACE are instruments optimized for
measurements of the chemical and isotopic composition of solar and
interstellar matter. SWICS determines uniquely the chemical and
ionic-charge composition of the solar wind, the temperatures and mean
speeds of all major solar-wind ions, from H through Fe, at all solar
wind speeds above 300 km/s (protons) and 170 km/s (Fe+16), and
resolves H and He isotopes of both solar and interstellar
sources. SWICS will measure the distribution functions of both the
interstellar cloud and dust cloud pickup ions up to energies of 100
keV/e. SWIMS will measure the chemical and isotopic and charge state
composition of the solar wind for every element between He and
Ni. Each of the two instruments uses electrostatic analysis followed
by a time-of-flight and, as required, an energy measurement. The
observations made with SWICS and SWIMS will make valuable
contributions to the ISTP objectives by providing information
regarding the composition and energy distribution of matter entering
the magnetosphere.

SWICS level 2 data is organized into 27-day time periods (Bartels
Rotations - roughly one solar rotation period). For each Bartels
Rotation, the level 2 data contains time averages of solar wind
parameters over the following time periods:

- hourly
- daily
- 27 days (1 Bartels rotation)

SWICS level 2 data consists of the following solar wind data items:

- Bulk and Thermal ion Speeds (km/s) => H+, He+2, O+6, Mg+10, and Fe+11

- Ratio of Elements => 4He+2/O, 20Ne+8/O, 24Mg+10/O, and 56Fe+(7 to 12)/O

- Ratio of Charge States of the Same Element => C+5/C+6, O+7/O+6, and Fe+11/Fe+9

- Isotope ratios => 3He/4He, 22Ne/20Ne, 24Mg/26Mg

See:
http://www.srl.caltech.edu/ACE/ASC/level2/swics_swims_l2desc.html

搭载于ACE（Advanced Composition Explorer，高级成分探测器）的太阳风离子组成光谱仪（SWICS，Solar Wind Ion Composition Spectrometer）与太阳风离子质谱仪（SWIMS，Solar Wind Ion Mass Spectrometer），是专为测量太阳与星际物质的化学及同位素组成而优化设计的探测仪器。SWICS可精准测定太阳风的化学组成与离子电荷态组成，涵盖从氢（H）至铁（Fe）的所有主要太阳风离子的温度与平均速度，适用于所有速度高于300 km/s（质子）、170 km/s（Fe+16）的太阳风，并可分辨太阳与星际来源的氢及氦同位素。此外，SWICS可测量星际云与尘埃云pickup离子（pickup ions）的分布函数，最高测量能量可达100 keV/e。SWIMS则可测量氦（He）至镍（Ni）之间所有元素的太阳风化学组成、同位素组成及电荷态组成。两款仪器均采用静电分析结合飞行时间（time-of-flight）测量的方案，并根据需要辅以能量测量。通过提供进入磁层的物质组成与能量分布相关信息，SWICS与SWIMS获取的观测数据将为国际日地物理计划（ISTP，International Solar-Terrestrial Physics）的科学目标实现提供重要支撑。

SWICS二级数据以27天为周期进行组织（巴特尔自转周期，Bartels Rotations——约为一个太阳自转周期）。对于每一个巴特尔自转周期，二级数据包含以下时段的太阳风参数时间平均值：
- 逐小时平均值
- 逐日平均值
- 27天（1个巴特尔自转周期）平均值

SWICS二级数据包含以下太阳风数据项：
- 离子整体与热运动速度（km/s）：涵盖H+、He+2、O+6、Mg+10及Fe+11
- 元素丰度比：包括4He+2/O、20Ne+8/O、24Mg+10/O及56Fe+(7 to 12)/O
- 同一元素的不同电荷态丰度比：包括C+5/C+6、O+7/O+6及Fe+11/Fe+9
- 同位素丰度比：包括3He/4He、22Ne/20Ne及24Mg/26Mg

详见：
http://www.srl.caltech.edu/ACE/ASC/level2/swics_swims_l2desc.html