铁磁共振报告.doc

实 验 报 告09级06系 姓名： 学号：实验题目：铁磁共振实验目的：学习用传输式谐振腔法研究铁磁共振现象，测量YIG小球（多晶）的共振线宽和g因子。实验原理：（略，详见预习报告）实验仪器：微波发生器，隔离器，定向耦合器，晶体检波器，微安计，谐振腔，铁氧体小球，精密衰减器，磁铁，示波器实验步骤：一.谐振频率的测量1.打开微波电源，先预热半个小时左右；2.调节衰减器，使微安表示数为50A 左右；3.旋转波长计的螺旋测微器，当电流达最小值时，读取螺旋测微器刻度值，重复六次，记录六个刻度值；4.根据刻度值与频率的关系对照表，得到相应的微波频率值，并记录；二.IB曲线的测量1.将电磁铁连入电路，调节励磁电流从0开始由小到大再由大到小（02.5A）变化，分别找到上升和下降电流变化最快的B所对应的I值（上升两个，下降两个）；2从零开始在上升的两个点外的区间每隔0.05A读一次电流表示数并记录，在此两点间的区间每隔0.01A读一次电流表示数并记录，（02.4A试验中励磁电流最大只可以调到2.4A）；3从2.5A开始下调励磁电流，在下降两点外的区间每隔0.05A读一次电流表示数并记录，在此两点间的区间每隔0.01A读一次电流表示数并记录（2.40A）。三.用示波器观察共振图像将励磁电流调至使电流表示数最小的位置，此时发生共振，将示波器接入电路，调节示波器，可出现共振图像，观察并记录波形。四整理仪器注意先将励磁电流调到零，再关闭电源。数据处理及误差分析：1. 用波长计测微波频率123456（mm）2.9552.9522.9532.9562.9542.955(MHz)8998.489998998.88998.28998.68998.4得平均微波频率=1/6(8998.4+8999+8998.6+8998.2+8998.6+8998.4)MHz=8998.6 MHz2.用非逐点调谐法测出I-B曲线数据如下表上升数据下降数据励磁电流（A）磁感应强度（mT）输出电流(uA)励磁电流(A)磁感应强度(mT)输出电流(uA)03.1552.441861.10.0511.8552.35409610.120.2552.3400610.1529552.25391610.237.5552.238260.50.2546552.1537959.70.355.5552.1370590.3564552.09368.258.10.472.8552.08366.457.80.4581.9552.07364.6570.590.9552.06362.856.40.5598.8552.0536155.10.610655.12.04359.2540.6511555.12.03357.452.90.712555.22.02355.6520.7513555.22.01353.8500.814555.1235248.90.85150551.9935047.20.915954.91.9834844.30.9517554.91.97346411175.254.91.9634438.21.0518454.51.95342351.119454.21.94341.4321.15201541.93340.829.51.221053.81.92340.225.41.25217.553.51.91339.623.81.26219.253.21.9339211.27220.953.41.8933720.11.28222.653.21.88335201.29224.353.21.87333201.322653.41.8633121.31.31227.853.81.8532923.41.32229.6541.84327.224.11.33231.4541.83325.427.21.34233.2541.82323.629.21.35235541.81321.8311.36236.5541.8320321.3723853.81.7931834.61.38239.553.51.78316361.3924153.41.7731437.51.4242.553.11.76312391.41244.253.31.7531041.91.42245.953.31.74308.242.41.43247.653.21.73306.443.31.44249.353.21.72304.644.81.4525153.11.71302.845.31.46253531.7301471.4725552.81.69299.247.81.4825752.71.68297.4481.4925952.41.67295.648.81.526152.31.66293.849.11.51263.852.21.6529249.81.52266.6521.64290.2501.53269.4521.63288.450.41.54272.251.61.62286.650.91.5527551.51.61284.8511.56276.2511.628351.91.57277.451.11.59282.252.21.58278.6511.58281.452.81.59279.850.61.57280.6531.628150.41.56279.853.21.6128349.91.5527953.51.6228549.81.54277.253.91.6328749.51.53275.453.91.6428949.31.52273.653.91.6529148.81.51271.854.11.66292.848.51.527054.31.67294.648.11.4526055.81.68296.447.61.425156.71.69298.247.11.35241571.730046.31.323657.51.7130245.31.25227581.72304451.2219.958.21.73306441.1521058.51.7430843.11.120058.81.7531042.81.0519158.91.7631240.91182591.7731439.10.9517759.21.7831638.30.916659.51.7931837.30.8515959.51.832035.10.815059.61.81320.433.70.7514059.71.82320.8320.713859.71.83321.2300.6512259.71.84321.627.70.611559.71.8532226.20.5510659.71.86325.425.20.599.959.71.87328.823.50.459059.71.88332.221.50.48059.71.89335.620.50.357259.71.933920.20.36259.71.91339.419.80.255559.71.92339.8200.24259.71.93340.221.50.153359.71.94340.622.10.12659.71.95341270.051959.71.9634328.603.559.71.9734531.51.9834734.51.9934940235142.72.01352.8432.02354.648.12.03356.4502.04358.251.12.0536053.22.06362542.0736455.12.0836655.72.09368562.1370572.11371.857.82.12373.6582.13375.458.92.14377.2592.1537959.12.16379.459.52.17379.859.72.18380.2602.19380.6602.238160.22.25391612.3400612.35409612.441961.1利用origin作出图像如下：黑线： 上升红线： 下降图一 上升及下降IB曲线图(1) 上升曲线由图像得最低点为（339.1, 20.2） 最高点 I0= 55.1uA Ir=20.2uA由I1/2=2 I0 Ir/( I0 +Ir)得I1/2=255.120.2(55.1+20.2)uA=29.6uA做I=29.6得直线与图像交于两点（321.4, 29.6） （343.4, 29.6）B=343.4-321.4=22 mTBr=(343.4+321.4) /2=322.4 mT已知,结合可知；查表知:，则g因子（2）下降曲线由图像得最低点为（335.2, 20.0）最高点I0= 59.7uA Ir=20.0uA由I1/2=2 I0 Ir/( I0 +Ir)得I1/2=259.720.0(59.7+20.0)uA=30.0uA做I=30.0得直线与图像交于两点（322.6, 30.0） （340.7, 30.0）B=340.7-322.6=18.1 MHzBr=（322.6+340.7）/2=331.7 MHz则g因子3. 用示波器观察共振图像图像如下：图二 示波器观察到的共振图像分析：在输入电流固定的情况下，电磁铁产生的磁场磁感应强度固定，简谐磁场叠加在感应磁场上，大小随周期变化，这时就会出现手动调整输入电流时的整个过程所得的图形即李萨如图形，由于磁场大小上升和下降时有剩磁的差别，所以正反向存在差别。误差分析：实验中仪器仪器并不十分准确，励磁电流甚至经常波动，使磁场不稳定，造成系统误差；读电压表示数时，有估读，会有读数误差，但经过多次读数，可以抵消部分误差。实验小结：本次试验总体较为顺利，只是读数特别多，需要有耐心； 试验中必须注意安全，不能带电接线，防止触电； 由于电磁铁中有剩磁，若不将励磁电流调为零就关闭电源，电磁铁中剩余磁能则转化为电能回到仪器，容易损坏仪