Ion Sources
A good ion source should provide a strong ion beam without consuming much of the gas. For hydrogen isotopes, production of atomic ions is favored over molecular ions, as atomic ions have higher neutron yield on collision. The ions generated in the ion source are then extracted by an electric field into the accelerator region, and accelerated towards the target. The gas consumption is chiefly caused by the pressure difference between the ion generating and ion accelerating spaces that has to be maintained. Ion currents of 10 mA at gas consumptions of 40 cm3/hour are achievable.
For a sealed neutron tube, the ideal ion source should use low gas pressure, give high ion current with large proportion of atomic ions, have low gas clean-up, use low power, have high reliability and high lifetime, its construction has to be simple and robust and its maintenance requirements have to be low.
Gas can be efficiently stored in a replenisher, an electrically heated coil of zirconium wire. Its temperature determines the rate of absorption/desorption of hydrogen by the metal, which regulates the pressure in the enclosure.
Read more about this topic: Neutron Generator
Famous quotes containing the word sources:
“Even healthy families need outside sources of moral guidance to keep those tensions from imploding—and this means, among other things, a public philosophy of gender equality and concern for child welfare. When instead the larger culture aggrandizes wife beaters, degrades women or nods approvingly at child slappers, the family gets a little more dangerous for everyone, and so, inevitably, does the larger world.”
—Barbara Ehrenreich (20th century)