Technology of^3He Imaging with polarized^3He gas

我们发展了一种利用布鲁特力方法(BFM)产生超极化气体的方法，即在极低的温度(~10mK)和强磁场(~17T)的作用下，为^3He-MRI产生高极化的~3He气体。我们之所以使用BFM，是因为由已建立的激光光泵产生的超极化~3He的产生率限制在1升/天左右，而BFM的超极化~3He的产生率有望超过1000升/天。目前，我们使用从荷兰莱顿低温公司引进的^3He/^4He低温系统(DRS2500)与波美兰丘克池一起实现低于10mK的温度，并使用超导螺线管线圈实现17T的强磁场。我们几乎已经准备好用一种叫做快速熔化的方法来检验超极化固体~3He在没有大的自旋弛豫的情况下通过液体汽化的有效性。我们已经开始了产生超极化~3He气体的初步实验。

We have developed a method to create the hyperpolarized, i. e., highly polarized^3He gas for the^3He-MRI using the Brute Force Method(BFM), where an extremely low temperature(～ 10mK), and a strong magnetic field(～ 17T) are employed. The reason why we use the BFM is that the production rate of the hyperpolarized^3He created by the well established laser optical pumping is limited to about 1 liter/day, while that for the BFM is expected to exceed 1000 liter/day.Currently, we use the^3He/^4He cryogenic system(DRS2500) introduced from the Leiden Cryogenics, the Netherlands to realize a temperature lower than 10mK together with a Pomeranchuk cell, and the superconducting solenoidal coil to realize a strong magnetic field of 17T. We are almost ready to check the validity of the vaporization of the hyperpolarized solid^3He through a liquid phase without sizable spin relaxation by use of a method called a rapid melting method. We have started a preliminary experiment toward the production of the hyperpolarized^3He gas.