41. Fusion reactions power the sun and stars.42. The easiest fusion reaction to achieve is found in a 50 50 mixture of tritium and deuterium. 43. Over the decades, scientists have spent billions of dollars to mimic the sun's hot-fusion reactions on earth. 44. Cross sections for many fusion reactions were measured ( mainly in the 1970s ) using particle beams. 45. The result is an object massive enough to undergo nuclear fusion reactions _ a star, like the Sun. 46. Fusion reactions combine light plasma state.47. The other basic type of nuclear weapon produces a large proportion of its energy in nuclear fusion reactions . 48. US experiments soon demonstrated the same neutrons, although temperature measurements suggested these could not be from fusion reactions . 49. This was used in the 1970s and 1980s to study the cross sections of high energy fusion reactions . 50. In 1977 construction began for 6 metre ( 20 foot ) superconducting electromagnets intended to control fusion reactions .
