solve previous 有时候会简写成solve ……prev 

类似solve init 不过解的条件一个是init设定的都是0的初始状态，一个是previous 设置的状态。

单粒子效应：

singleeventupset entrypoint="0,-20,0" exitpoint="0,420,0" \

#入射点和停止的坐标

b.density=$density pcunits radius=0.02 t0=5e-12 tc=2e-13

#totc 还不清楚

method max.temp=1000000 maxtraps=100 dt.min=1e-50 dt.max=10000 tol.time=1e6 \

climit=1e-6

The radiation source and dose rate are defined in the radiation statement. Here a 10keV XRay source and a dose rate of 1 Rad per second is defined, using the radiation statement:

radiation doserate=1 XRay

The convenience of defining a dose rate of 1 Rad per second is that the total dose will be the same as the elapsed transient time in the solve statement, if the parameter "radiation" was invoked in the transient from the start.

# Self-Consistent Fowler-Nordheim Gate Current

#定义FN 栅电流需要什么模型

models consrh cvt auger fn.cur nearflg

The energy of the Single Event Strike is characterized by a parameter called the "Linear Energy Transfer", or LET. The higher the LET, the greater the energy of the incoming particle or photon. In this example, the LET value of the incoming strike is set up as a variable, by the line "set LET=1", which creates a variable called "$LET" and assigns it a unity value. In order to

#LET越大，注入能量越大。可以设定值的大小。

convert the units of LET into units of pico Coulombs/cm3 of track charge density, the LET value needs to be multiplied by 0.01035 for silicon material. A second variable called "$density" is assigned this converted pico coulomb value. Lastly, the

#为了把它转化成电荷密度的轨道密度pico Coulombs/cm3，需要成0.01035，就可以得到density这个参数

units of the strike are specified to be these same pico coulomb units, by the parameter "pcunits" in the "singleeventupset" statement that describes the time and track positional properties of the strike.

#参数pcunits和density参数是一样的，单位也是pico coulomb units 描述了单粒子翻转中的时间和轨迹特性

Simulation of a 6 transistor SRAM cell, with a Single Event Strike on one of the nMOS transistors, can now be simulated directly in SmartSpice using the newly creted data file. The strike can also be associated with a time delay before the strike occurs. This delay is implemented in the "VSEU" line of the SmartSpice section of the input file, and is specified using the "TD" parameter. In this simulation, the delay before the Single Event Strike is set to be 0.5 micro-seconds by setting the parameter "TD=0.5u" on the "VSEU" statement.

#6管子SRAM 可以直接在SmartSpice 中仿真。轰击还可以与轰击发生之前的时间延迟相关联。 此延迟在输入文件的SmartSpice部分的“ VSEU”行中实现，并使用“ TD”参数指定。 在此模拟中，通过在“ VSEU”语句上设置参数“ TD = 0.5u”，将单粒子效应之前的延迟设置为0.5微秒。

DoseRate 为公式(2-13)中的剂量，默认单位为 rad/s

DoseTSigma 则将辐照时间和辐照射线的高斯分布标准偏差结合，默认单位为 s