Heavy water is heavy because the hydrogen in it weighs twice as much as ordinary hydrogen (it has a proton and a neutron in its nucleus, instead of just a proton).

重水之所以重是因为水中氢的重量是普通氢的两倍（它的原子核中有一个质子和一个中子，而不仅仅是一个质子）。

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This is the DEUT ERIUM PLANT, an automated facility for extracting the heavy isotope of hydrogen from the local water supply.

实际上这是个加工厂一个全自动化的设施通过来从当地水源中提取氢气的重同位素来生产氘气。

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Among this group, most of those with traces of heavy elements also have traces of hydrogen.

这类白矮星中有着重元素痕迹者，大多也会有氢的痕迹。

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Unlike the sort of fusion done in big machines, which squeeze heavy hydrogen nuclei together, no neutrons are released in this reaction.

ECONOMIST: A novel form of fusion power

In the Nature study, Brian Naranjo and colleagues, from the University of California-Los Angeles (UCLA), initiated fusion of heavy hydrogen, or deuterium, using the strong electric field generated in a pyroelectric crystal.

BBC: NEWS | Science/Nature | Table-top fusion 'demonstrated'

For the test run, Mr Lerner used deuterium, a heavy isotope of hydrogen, as the gas.

ECONOMIST: A novel form of fusion power