15.08.2018

Beam lines

 

Heavy-ion and low-energy proton line

At RADEF, heavy-ion and low-energy proton (<6 MeV) irradiations are performed on the main beam line. At the end of the line is a vacuum chamber with an inside diameter of 75 cm and a height of 81 cm, whose purpose is to offer a vacuum environment between the beam exit window and the surface of the DUT, to minimise the spread in particle energy. Low-energy proton tests are always carried out in vacuum, while heavy-ion tests can be carried out in vacuum or in air, depending on the energy. The irradiation chamber can be lifted to allow for easy access to the DUT, and also features a small side window for quick access, large enough to fit one's head and arm. Inside the chamber is a motorised platform that can be used to remotely move the DUT in front of the beam: the linear movement apparatus (LMA). On the following picture, the LMA is showed, in front of the beam exit window, in the open chamber (open-air test configuration).
Thanks to the LMA, the DUT can be translated along the horizontal and vertical axes and tilted around the vertical axis. The components can be fixed on a 25x25cm² metal plate which will be mounted on the LMA. RADEF staff will take care of making necessary holes in the plate to accommodate the user's DUT; however, customers can also make their own fixture plates if desired. Mechanical drawings for this plate can be found here.

Because room is limited inside the vacuum chamber, if vacuum tests are needed, we ask our customers to make sure that their DUT is of a size small enough to be fitted on the LMA in the 81 cm-large chamber, taking into account any eventual translations and rotations that they will require during the tests.

A CCD camera with a magnifying telescope is located at the other end of the beam line, which allows easy setting of the collimators and accurate determination of the region of the DUT which will be exposed to the beam. The collimators can be set to an arbitrary rectangle of a size up to 10x10 cm.The coordinates of the targets of interest on the DUT as well as the required collimator settings are stored in the computer’s memory, allowing for fast target switching during the test with a simple click.

Around the chamber are several cylindrical windows that can be closed with different lids, each fitted with a different set of feedthroughs. These can be combined to offer all the electrical interfaces needed by the DUT. The following figure shows these interfaces as well as those between the experiment cave and the user control room.

A detailed list of the lids available for the chamber:

  • Large window: 22 x BNC
  • Small windows
  • 4 x DB-25 (25 pin) sockets
  • 6 x SMA connectors
  • 4 x IDE/Parallel ATA (2*20 pin, 0.1 inch pitch) sockets
  • 6 x RJ-45 (Ethernet) connectors
  • 8 x BNC connectors

If your application requires additional or uncommon interfaces, purpose-made connector lids can be made on request in Jyväskylä. Here is an example of a piece manufactured on demand for a RADEF customer:

Links to the control room: A wall separates the experiment room from the control station, and to communicate with the DUT and their equipment in the cave, customers can use existing interfaces. These are a pair of DB-25, a pair of DE-9 and an IDE/P-ATA 40-pin connectors, three BNC connectors and an Ethernet cable. If extra cables have to be used they will have to go through the corridor to the control room (which will require almost 20 metres of cabling).

High-energy proton line

In the RADEF facility, proton irradiations above 6 MeV are not performed in the main line's vacuum chamber, but on a separate dedicated station, in air. The proton beam passes through a 200μm thick tungsten foil which isolates the beam line vacuum from the ambient pressure. The distance between the DUT and the beam exit window can be altered as required, however, the distance is usually kept around 1 meter. Before the DUT there is a collimator unit (not shown in the picture), which size can be set from 0x0 to 10x10cm2 and which shape can be any rectangle. The proton station's DUT support plate can not be remotely operated from the barracks - it has to be moved manually.