In this study, the Li^{+} ion emission characteristics of
It is well known that when
Although there are some studies [6,7] that have used a Li^{+} ion beam produced from
For the beneficial treatment of
To fabricate
The RGA can detect the relative quantities of emitted ions as well as neutral atoms as a function of mass number.
The resistivity of a material depends on temperature. Using this information, we can measure the temperature of a material. If we can measure the resistance of a material, we can calculate the temperature by converting the resistance into the temperature. In the case of a conductor, the resistance as a function of temperature is given by
A degassing procedure was carried out before the RGA experiment. During the degassing process, CO_{2}, H_{2}O, and N_{2} peaks became stronger; however, after finishing degassing, these peaks became smaller.
Figure 1 shows the RGA spectra when the source power is off (closed circles) and when it is on (open circles). In this figure, the source potential was fixed at 100 V, and the source temperature was 1300 K when the source power was on. Li^{+} emitted from the source was accelerated toward the plate. Some Li^{+} ions were adsorbed on the plate surface, and some were scattered from the plate surface, arriving at the RGA detector. When the source power was off, the spectrum showed small H_{2}, N_{2}, and CO_{2} peaks. These peaks are very small compared with the Li peak, and the intensities of these peaks are almost the same as the peaks that appear when the source power is off, i.e., the prepared
Figure 2 shows the Li^{+} ion current versus source temperature. The source potential is fixed at 100 V.
This figure shows the current increasing exponentially with increasing source temperature. This result can be explained by the thermionic emission equation (see
where
In the case of an ion, the work function ef should be replaced by another physical quantity that the emitting energy
It is difficult to know whether or not this result satisfies the Richardson equation, and we cannot estimate the emitting energy
If the result shown in Fig. 2 satisfies the Richardson equation, the plot of
Figure 3 shows the plot of
The emission current depends on the source potential as well as the source temperature. The Child-Langmuir model [12–14] explains the relationship between the current density and applied potential. The equation they derived is
where
Figure 4 shows Li^{+} ion current versus source potential when the source temperature is fixed at 1100 K. As expected, the plot line is not straight, but curved. For detailed analysis, we rearranged
The plot of
Figure 5 shows the plot of
They derived this equation for two parallel plates, i.e., in a rectangular coordinate; however, our experimental system is not a rectangular coordinate. In this study, expressing the equation in spherical and cylindrical coordinates was attempted, and it was found that the equations obtained in the different coordinates have the same form, i.e.,
Combining the source temperature dependence function and the source potential dependence function, a new current-temperature-potential equation is suggested,
where
The number of Li atoms in the specimen is finite. Similar to radioactivity decay, the ion current decreases as in the following equation.
where
Figure 6 shows normalized Li^{+} ion currents versus working time for the source temperature 1301 K and the source potential fixed at 100 V, in which exponential decay is demonstrated showing good agreement with
Because the emission current depends on the source temperature, the
where
Therefore, the half-life time is given by
Figure 7 shows the half-life times determined by experiment and theoretical plot using
The high source potential could reduce the half-life times. By the same method explained above, we conclude that the half-life times should be proportional to
Combining the source temperature dependence and the source potential dependence, we conclude that the half-life time is given by
where
Note that the half-life time at a source temperature of 1100 K and source potential of 100 V was 10000 min, and the initial current was 10
Finally, this study suggests the emission current equation as a function of the source temperature, the source potential, and the half-life time
where
If we measure the initial current, the temperature, and the source potential, these equations enable us to estimate the lifetime and current as a function working time. If we know
In this study, the Li^{+} ion emission characteristics of