Fast Gas Injection System

The General Atomics fast gas injection system is designed for injecting short (millisecond or longer) pulses of nonreactive gases into a vacuum system. The level of flow is measured with a small pressure sensor and the flow is feedback regulated so that the actual flow matches the demand.

Originally developed for fusion research devices, the piezoelectric valves and pressure sensors can be used in large magnetic fields. They are made of completely nonmagnetic materials and have been used in magnetic fields up to 2.4 T.

Gas Injector

Valve Controller

The valve controllers, which contain the control and feedback circuitry, are mounted in a separate chassis which can be separated from the valves by up to 30 meters. Up to 4 valves can be controlled by individual plug in modules in one of the chassis. The flow can be manually set from the front panel of the controller or remotely programmed using an input voltage.


  • piezoelectric gas injection valve
  • flow rate up to 500 torr-liter/s
  • opening time: 2 ms after application of voltage
  • flow measured by pressure sensor mounted on valve
  • valve and pressure sensor insensitive to DC magnetic fields
  • gas pressure up to 6.5 atm (absolute)
  • gas input: miniconflat flange
  • mounting: 2 3/4 inch conflat flange
  • alternate vacuum flanges available


  • controls up to 4 gas injectors through individual plug-in modules
  • local manual control or external voltage programming for each control module
  • voltage control in range of 0-10 V
  • 0-10 V analog output from pressure (flow) sensor on each valve
  • adjustable voltage waveform to match characteristics of various piezoelectric valves
  • up to 30 meter cable lengths to valves


  • Doublet IIA, Doublet III, DIII-D at GA

  • ISX-A, ISX-B at ORNL

  • TEXTOR at IPP Jülich

  • ASDEX-Upgrade , Wendelstein 7AS at Max-Planck-Institut-für-Plasmaphysik

  • ZT-40 at LANL
Prices vary according to system configuration, interface requirements and shipping costs.

Representive prices (March, 2001):
  • One valve controller, one valve control module, and one valve: $48,000.
  • One valve: $11,500. For orders of more than one valve, the price per valve will drop and will depend on the number of valves.
  • Additional valve control modules (the controller has room for 4): $6,500.

For a formal quote, contact Dr. Keith Burrell, 858 455-2278.