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Instrumentation & Commissioning

enlarged view

The three installation stages of bERLinPro: (1) Low-energy section, (2) new GUN-2 module, (3) LINAC module and high-energy recirculator.

For achievement of the ambitious goals parameters of bERLinPro, it is necessary to develop specific commissioning strategies for each construction stage. It means: What kinds of monitors with a demanded resolution and dynamic range are needed to setup the accelerator properly?

The question does not only cover the measurement of the intrinsic properties of the electron beam like energy, emittance, current, etc. but also how to determine the relative and absolute alignment between the electron beam and a certain device like a bending magnet or cavity, and furthermore to correct an identified malposition.

In case of high current ERLs, special emphasis is put on the scope:

1. Electron bunch pulse patterns with various frequencies and with scaling beam currents from about nanoampere's (10-9) for the machine startup to few tenth of milliampere's (10-1) for the norminal operation mode. This span of eight orders of magnitudes ought to be measured (interceptive and non-invasive) and controlled.

2. At high beam currents or beam power, harmful beam loss can arise on very short time scales (microseconds) and destroy permanently the accelerator structure. Causes can be for example beam HALO formation (relative intensity level of 10-5), collective instabilities ( like beam breakup) or system failures. A sophisticated machine protection and inhibit system is goging to be developed. 

3. For excellent energy recovery the path length of the recirculator has to be adjusted to the right phase advance of 180 deg in the LINAC. Also the collinearity of the high- and low-energy beam by a simultaneously position measurement has to be ensured.