Tandem accelerator

The tandem accelerator in a general term is a type of electrostatic accelerators, which have two-step accelerations of ion particles with one high voltage terminal
("Tandem" is a pair of horses harnessed in a single file in literal meaning).
The high voltage is generated by carrying electric charges on running pellet chains to a high voltage terminal.
There are two accelerator tubes from the ground to the terminal and vice versa.
Between the two accelerations, the charge state of ions is transformed
from negative to positive ones at the voltage terminal.
Negative ions, which are atoms united with another electron, are produced in the negative ion source.
The negative ions are pre-accelerated at the exit of the source
led to the entrance of the low energy accelerator tube and accelerated for the positive high voltage terminal. On arriving at the high voltage terminal, the ions go through an electron stripper (a carbon foil) to be positively charged due to losing many electrons.The highly charged positive ions are accelerated again through high energy accelerator tube down to the exit.
The high energy ions play an important role to the advanced studies in nuclear physics, materials science and so on, since the ion beams from the tandem accelerator can be precisely controlled in energy, kinds of ions, and beam currents.

Major items of the tandem accelerator

Pressure vessel diameter, 8.3m; height, 26.6m Insulating support diameter, 2.74m; height, 13.72m
High voltage terminal diameter, 3.51m; height, 4.47m Insulating gas pure SF6 gas, 6.7 kg/cm2 in absolute pressure
Charge carrying device 2 parallel pellet chains Voltage divide resistor method
Power conveyer rotating shaft(made of acrylic resin)method Control system parallel computing system through the medium of CAMAC
Target room Five rooms,
10 beam lines
3 beam lines for the booster
Ions available for acceleration From hydrogen to bismuth
Terminal voltage 2.5~18 MV Beam current (Example) Hydrogen, 3 pµA
Carbon, Fluorine, 0.5 pµA
Argon, Xenon 0.1 pµA
Injection energy for negative ions 50~350 keV

An outline of the tandem accelerator system

Negative ion Positive ion Accelerated ion by the superconducting booster