MBE Components, Valved Alkali Metal Source AKS


Valved Alkali Metal Source


AKS 63-150
AKS 63-150 valved alkali metal source on DN63 CF (O.D. 4.5") mounting flange with 150 cm³ evaporator reservoir and shutter
  • Compatible with most MBE systems

  • Large capacity 150 cm3 evaporator

  • Ideal source for Cs and Rb evaporation

  • Easy and safe refilling procedure

  • Precise and very fast flux control

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The Valved Alkali Metal Source AKS is designed for evaporation of elemental high vapor pressure alkali metals like cesium (Cs) and rubidium (Rb) in standard MBE or UHV systems.

The AKS provides precise metal flux stability of better ±0.1% by ±0.03K temperature control of the metal reservoir using external heating.

The integrated pneumatic all metal valve enables rapid on/off switching of the atomic beam. Its vaccum tight construction allows venting the MBE system without breaking the vaccum inside the AKS evaporator.

Equipment of the AKS system

HPM power supply, controllers, cables and heating thermostat of the AKS system

The AKS consists of the 150 cm3 reservoir, precisely heated by a closed cycle heating thermostat, the heated valve and the heated injector unit which acts as interface to the UHV system. Both components, valve and injector, are independently heated electrically to avoid material condensation. An additional rotary shutter is available on request. The injector tube is water cooled on its outside to reduce the thermal load on the UHV system and to minimize outgassing during operation.

An easy and safe refilling procedure is provided by the use of a removable additional reservoir. This heatable refilling unit can be filled with reactive alkali metal source material within an inert gas floated external glove box, closed tightly and be mounted to the source. Thus, “quasi in-situ refilling” of the evaporator reservoir is made possible.

Refilling unit

Refilling unit for AKS evaporator reservoir



The main purpose of the Valved Alkali Metal Source AKS is the controlled evaporation of elemental alkali metals like Cs or Rb from the heated reservoir inside the cell into a vacuum chamber under high to ultra-high vacuum conditions (i.e. pressures below 1x10-6 mbar).

Typical applications for the AKS are:
  • layer growth of Cs or Rb in MBE and surface science applications

  • MBE fabrication of alkali metal based electronic devices, e.g. infrared-sensitive photocathodes

Schematic drawing AKS
  1. Heated injector tube
  2. Cell flange
  3. Pneumatic valve for flux switch
  4. Evaporator reservoir
  5. Refilling reservoir (removable)


Technical data

Filament type 3 separate heater circuits (evaporator reservoir, valve & injector units)
Thermocouple 2x type K Chromel/Alumel (injector/valve); 1x PT100 (evaporator reservoir)
Operating temperature injector: 300°C; valve: 300°C; reservoir: 270°C
Outgassing temperature injector: 300°C; valve: 300°C; reservoir: 270°C
Bakeout temperature 200°C
Evaporator reservoir
150 cm³
Flux control switchable valve unit
Valve control pneumatic operation, manual and remote control with TTL signal


Specific data

For general information on CF mounting flanges see Flange and Gasket dimensions.

images/header_nominal_capacity.gif images/header_options.gif
[cm3] [mm] / [mm] [W] / [A] Product code
AKS 63* - 150- S**- LxxxD57 2300 / 10 HPM control unit
* other mounting flange diameters on request
** rotary shutter possible on same flange (requires min. tube I.D. 63mm)
*** specify UHV length L with order


Product code:

e.g. AKS 63-150-S-L300D57

is a valved alkali metal source on DN63 CF flange with 150cm³ evaporator reservoir, shutter and UHV-length 300mm.


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