Richardson further studied the positive ions around hot objects. He finally figured it out through a lot of experiments that the generation of positive ions is very complicated. Some are emitted by the electrode itself during heating, some are caused by impurities, and some are indeed the result of the interaction between the heating electrode and the surrounding gas.

Richardson also found that when a solid sample is heated for the first time, a large number of positive ions will always be released, forming a transient current. After removing impurities, positive ions began to emit stably. The transient current is obviously caused by impurities, and the steady current is composed of positive ions generated by the electrode itself.

In order to test whether the basic premise on which the formula (28- 1) is derived is correct, Richardson proposed two methods. One way is that if electrons really escape from the hot body by overcoming the kinetic energy of work function W, the hot body will be cooled down by this process. Richardson made a calculation in 1903. In 1909, A.Wehnelt and F. Qin Xi confirmed this experiment for the first time, but the numerical value was inconsistent with the theory. 19 15 years, Richardson and H.L. Cook cooperated to improve the experimental method, and finally confirmed the correctness of the theory.

The other way is the opposite process. Richardson suggested that if the electron beam flows into the conductor from the outside, the conductor should generate heat, and the heat has nothing to do with the temperature or the potential difference driving the electron flow. 19 10 year-1910 year. Richardson and Cook's experiments also positively proved this point.

Until 19 13, some people doubted the theory of thermionic emission. They always think that this is not a physical problem, but a chemical problem, which is a secondary process due to the chemical interaction between hot objects and surrounding gases. In 19 13, Richardson used tungsten with good calendering performance instead of platinum as the hot wire, and the vacuum condition was better, resulting in much larger emission current. He proved that the mass of emitted electrons greatly exceeds the sum of the mass of chemicals that may be consumed. So he convincingly made a judgment with conclusive facts.

19 1 1 year, Richardson strictly deduced the thermionic emission formula by thermodynamic method. In the derivation, the fact that electrons have no contribution to the specific heat of metals is considered, and the second formula is obtained:

I = A′T2exp(-W2/kT)(28-2)

Where A' and W' are two coefficients different from a and w, but they can be calculated with each other.

Two formulas, one related to T 1/2 and the other related to T2. Richardson thinks that Formula (28-2) is desirable because it has a better theoretical basis. The two formulas are consistent with the experiment within the error range, so it is impossible to make a judgment through the experiment.

In 19 15, Richardson proved that a' in formula (28-2) is a universal constant independent of materials, thus showing the superiority of formula (28-2). In 1923, S.Dushman concluded that

It is basically consistent with the experiment.

Then quantum mechanics developed. Surprisingly, the second thermionic emission formula put forward by Richardson in 19 1 1 has stood the test of quantum theory. From 1927 to 1928, Pauli and Sommerfeld applied Fermi-Dirac quantum statistical distribution to the motion of metal electrons, and the derived thermionic emission formula was completely consistent with Richardson formula (28-2).

Richardson was born in 1879, an industrial equipment manufacturer's family, and showed his talent from an early age. 12 years old, won a scholarship with excellent results in middle school and won the championship many times. From 1897, he entered Trinity College of Cambridge University with a scholarship and studied in Cavendish Laboratory led by J.J. Tang Musun. This year coincided with the discovery of electrons by J.J. Thomas. Richardson 1900 graduated from university. Because of his active research on thermoelectronics, the school kept him in Cavendish laboratory to continue his research. His work is creative, and he pays attention to both experiment and theory. 190 1 year, he read two papers at the Cambridge philosophy society, and put forward the law of thermionic compliance for the first time, which was well received by his peers. 1902, Richardson was elected as an academician of Trinity College. 1906, 27-year-old Richardson was invited to the United States and became a professor of physics at Princeton University, where he continued his research on thermions. The word thermdionics was first put forward by him in 1909 as the topic of the paper. Richardson's lecture notes for graduate students were published in 19 14, entitled "Electronicity of Matter", and later became the main teaching materials for students interested in electronics and radio. Among the graduate students he supervised were K.T. Compton and A.H. Compton. A.H. Compton won the 1927 Nobel Prize in Physics for his discovery of "Compton Effect".

Davidson, another graduate student, won the 1937 Nobel Prize in physics for his discovery of electron diffraction. Richardson brought the style of Cavendish laboratory of Cambridge University to the United States, which had a wide impact on scientific research and personnel training in the United States.

Richardson returned to England in 19 13. He has been a professor of physics at King's College London, chairman of the British Association A (192 1) and chairman of the London Physical Society (1926- 1928). 1939 was knighted. After 19 14, in addition to continuing to study thermoelectronics, we also studied the fine structure of electron emission caused by photoelectric effect, magnetic and chemical interaction, electronic theory, quantum theory, hydrogen molecular spectrum, soft X-ray and hydrogen spectrum Hα, deuterium spectrum Dα. In the early years (1907- 1909), Maxwell's law of molecular velocity distribution was experimented with thermionic emission. Later, in 19 17, he instructed Ding (Ding Xilin), a graduate student in China, to further study this subject. Ding's paper was published in 192 1. This is the only feasible experimental verification method before the molecular beam method was put forward, which has certain theoretical value.

During World War II, Richardson devoted himself to the research of radar, sonar, electronic detection instrument, magnetron, klystron and other projects. His scientific activities are closely related to radio electronics and constantly promote its development. He deserves to be the founder of thermoelectronics (hot cathode electronics).