Heavy water gets its name because it contains deuterium, a form of hydrogen that has a neutron in its nucleus as well as the usual proton and thus weighs twice as much as the ordinary sort.

重水因含重氢而得名。重氢是氢原子的一种，其原子核中含有一枚中子，加之正常氢元素中的质子，重量为一般氢原子的两倍。

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The moon's low gravity also means that water composed of regular hydrogen and oxygen will escape quicker than heavy water, perhaps leading to a concentration of deuterium in the water of the moon.

月球的低重力也意味着由普通氢气和氧气组成水将会比重水更快的消失，可能导致在月球上水的氘含量。

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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.

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It consists of 1, 000 tonnes of heavy water (the sort that has deuterium, a heavy form of hydrogen, in its molecules, instead of the normal, light form of the element).

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

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