Charged Particle Lunar Environment Experiment (CPLEE)

The Charged Particle Lunar Environment Experiment (CPLEE) was designed to measure the energy spectra of low-energy charged particles striking the lunar surface. It measured the fluxes of electrons and ions with energies from 40 eV to 20 keV. The primary purpose of the experiment was to examine plasma particles originating from the Sun and the low-energy particle flux in the magnetic tail of the Earth. The CPLEE had a mass of 2.7 kg, a stowed volume of 2540 cubic cm, and used 3.0 W power normally and 6.0 W at night when the survival heater was on.

The main part of the instrumentation consisted of two electrostatic analyzers. One of these (analyzer A) pointed toward local lunar vertical, and the other (analyzer B) to a point 60 deg from vertical toward lunar west. Both detectors had fields of view of 4 x 20 degrees; for analyzer A the long axis of the field of view was oriented N-S, and for analyzer B, E-W. As a first approximation, both detectors could be considered to point in the ecliptic plane. Each analyzer consisted of a set of direction-defining slits, deflection plates, five small-aperture (1 mm nominal) C-shaped channel electron multipliers, one large-aperture (8 mm nominal) helical channel electron multiplier and 6 accumulators. For a given voltage applied to the deflection plates, the five small-aperture multipliers were arranged to count particles of one polarity with differing energies, while the large-aperture multiplier simultaneously made a wide-band measurement of particles of the opposite polarity. During each 19.2-s interval in the automatic mode of experiment operation, deflection voltages of zero (twice, for background and calibration) and plus and minus 35, 350, and 3500 were applied to the deflection plates for 2.4 s at each voltage. Each analyzer would make measurements for 1.2 s and transmit while the other analyzer was operating. The little-used manual mode permitted the continuous application of a single deflection voltage, thus increasing temporal resolution for particles in a limited portion of the spectrum. Useful data obtained during each 19.2-s interval (automatic mode) were, for each analyzer, 1.2-s accumulated counts of electrons and ions in 18 energy windows between 40 eV and 20 keV. The windows utilizing all 6 detectors at 35 V are centered roughly at 40, 50, 65, 70, 95, and 200 eV, the windows at 350 V are 10x and at 3500 V are 100x these values. A dust cover with a 63Ni radioactive source on the underside over each aperture for calibration protected the instrument.

The ALSEP central station was located at 3.6440 S latitude, 17.4775 W longitude. The charged particle lunar environment experiment was deployed approximately 3 meters northeast of the central station. Leveling to 1.7 degrees, tipped to the east, was accomplished with a bubble level and east-west alignment to within 1 degree with a Sun compass. The instrument was deployed at approximately 18:00 UT on 5 February 1971 and commanded on at 19:00 UT for 5 minutes of functional tests. A checkout procedure was conducted on 6 February from 4:00 to 6:10 UT. Following LM ascent on 6 February at 18:49 UT the dust cover was commanded to be removed at 19:30 UT. The experiment worked normally from deployment until April 8, 1971, when the power supply for the analyzer pointing away from lunar vertical (analyzer B) failed. The other analyzer continued to function normally until June 6, 1971, when a partial failure of the power supply occurred. Operation of this analyzer was intermittent for the rest of 1971. During most of 1972, operation was continuous during lunar night and intermittent during lunar day because high temperatures caused a low voltage condition in the power supply. From December 1972 to February 1973 operation was continuous, after which time the voltage problems occurred again. The Apollo 14 central station signal was lost on 1 March 1975 and reacquired on 5 March. Loss and reacquisition of signal happened sporadically until termination of the ALSEP experiment. Loss-reacquisition occurred in 1976 on 18 January - 19 February, 17 March - 20 May, 8 June - 10 June, 9 October - 12 November and in 1977 on 30 July - 4 August. The CPLEE experiment was in standby mode when the ALSEP stations were turned off on 30 September 1977.

月球带电粒子环境实验（Charged Particle Lunar Environment Experiment，CPLEE）旨在测量撞击月球表面的低能带电粒子的能量谱。该实验测量了从40 eV到20 keV能量的电子和离子通量。实验的主要目的是研究来自太阳的等离子体粒子以及地球磁尾中的低能粒子通量。CPLEE的质量为2.7千克，收纳体积为2540立方厘米，正常工作时功率为3.0 W，夜间当生存加热器开启时功率为6.0 W。

仪器的主体部分由两个静电分析仪组成。其中之一（分析器A）指向局部月球垂直方向，而另一个（分析器B）指向偏离垂直方向60度朝向月球西侧。两个探测器均具有4 x 20度的视场；对于分析器A，视场的长轴朝向南北方向，而对于分析器B，则朝向东西方向。作为首次近似，可以认为两个探测器均指向黄道平面。每个分析仪由一组定义方向的狭缝、偏转板、五个小孔径（1毫米标称值）C形通道电子倍增器、一个大型孔径（8毫米标称值）螺旋通道电子倍增器和六个积累器组成。对于施加到偏转板上的特定电压，五个小孔径倍增器被排列以计数不同能量的单一极性粒子，而大型孔径倍增器则同时进行对相反极性粒子的宽带测量。在实验操作的自动模式中，每个19.2秒的时间间隔内，对偏转板施加了零电压（两次，用于背景和校准）以及±35、350和3500伏的电压，每次电压持续2.4秒。每个分析仪会对1.2秒内收集的电子和离子进行测量，并在另一个分析仪操作期间传输数据。不常用的手动模式允许连续施加单个偏转电压，从而提高了特定光谱范围内粒子的时间分辨率。在自动模式中每个19.2秒间隔内获取的有用数据包括，对于每个分析仪，在40 eV到20 keV之间18个能量窗口中1.2秒累积计数的电子和离子。在35伏时使用所有6个探测器窗口大致位于40、50、65、70、95和200 eV，350伏的窗口是前者的10倍，3500伏的窗口是前者的100倍。每个孔径下方的尘盖带有63Ni放射性源，用于校准，以保护仪器。

ALSEP中央站位于南纬3.6440度，西经17.4775度。带电粒子月球环境实验被部署在中央站东北约3米处。使用气泡水平仪进行1.7度的水平调整，向东倾斜，使用太阳罗盘进行东西方向的1度对齐。仪器于1971年2月5日约18:00 UT部署，并在19:00 UT进行了5分钟的功能测试。2月6日从4:00到6:10 UT进行了检查程序。2月6日18:49 UT的月球上升后，于19:30 UT命令移除尘盖。实验从部署到1971年4月8日一直正常工作，当时指向月球垂直方向外的分析器B的电源出现故障。另一个分析仪继续正常工作，直到1971年6月6日电源发生部分故障。1971年余下的时间，该分析仪的操作时断时续。1972年大部分时间，在月球夜间连续运行，在月球白天时断时续，因为高温导致电源电压低。从1972年12月到1973年2月，运行连续，之后再次出现电压问题。1975年3月1日，阿波罗14中央站信号丢失，于3月5日重新获得。信号丢失和重新获得在ALSEP实验终止前偶尔发生。1976年1月18日至2月18日、3月17日至5月20日、6月8日至6月10日、10月9日至11月12日以及1977年7月30日至8月4日发生信号丢失和重新获得。当1977年9月30日关闭ALSEP站时，CPLEE实验处于待机模式。