The diagram shows a proposal for a nuclear fusion test station. Deuterium and tritium nuclei are heated in a magnetic chamber. The magnets keep the hot gas ...
Question 1 Report
The diagram shows a proposal for a nuclear fusion test station. Deuterium and tritium nuclei are heated in a magnetic chamber. The magnets keep the hot gas away from the chamber wall. A turbine and transformer would transfer electrical energy to the grid.
In one possible reaction, a deuterium nucleus and a tritium nucleus join to form helium and a neutron.
(a) State the term used for the joining process in the magnetic chamber. [2]
(b) Explain why the nuclei must be heated to an extremely high temperature before fusion can occur. [4]
(c) Calculate the energy transferred in 30 s if the test station produces useful power of 2.5 MW. [3]
(d) Describe two difficulties that must be solved before nuclear fusion can provide reliable electricity at many power stations. [4]
Answer Details
(a) The joining process is nuclear fusion: light nuclei join together to form a heavier nucleus. [2]
(b) Deuterium and tritium nuclei are both positively charged, so they repel each other electrically. Heating gives the nuclei greater kinetic energy and speed. They can then collide closely enough for the strong nuclear force to overcome the electrical repulsion and join the nuclei. [4]
(c) Convert megawatts to watts and use \(E=Pt\):
\[P=2.5\text{ MW}=2.5\times10^6\text{ W}\]
\[E=2.5\times10^6\times30=7.5\times10^7\text{ J}\]
Energy transferred = \(7.5\times10^7\text{ J}\). [3]
(d) Two valid difficulties are needed, with description. The plasma must be heated to an extremely high temperature, and it must be contained without touching the chamber wall. Other valid difficulties are ensuring more useful energy is produced than is supplied to heat and contain the plasma, and developing materials that can withstand intense radiation and neutron damage. [4]
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