Triangular Beam Sweep Controller
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A triangular wave generator for driving the horizontal and lateral coils of the gun. Frequency range of each channel is 1 to 200 Hz and the peak amplitude is ±2 amperes. Rack mountable and includes all interconnecting cables.
Features:
- Triangular output
- Current regulated
- Independent amp/frequency control
- High 200 Hz frequency
- ±operation
New Sweep Coil for Higher Frequencies
Present day e-Gun technology does not allow for a sweep above 60 Hz. When trying to sweep above these frequencies, the beam spot shrinks in size and the electromagnet core becomes saturated and cannot respond to frequencies above 60 Hz. In order to prevent hot spots and tunneling the sweep must be above these frequencies. Thermionics' Hyper-Unimelt sweep can respond up to 200 Hz. This entitles users of subliming materials, for example, chrome or quartz, an extremely uniform melt temperature over the entire crucible sweeping area. Thus, hot spots and tunneling are eliminated.
Description
The Model XYS sweeper is designed to provide the required drive to the longitudinal and lateral coils of electron beam guns. The two outputs are independently variable such that the electron beam can be positioned anywhere over the entire surface of the crucible. In addition to this DC positioning, it also provides a variable amplitude/frequency to the coils so that the beam can be swept over the surface of the evaporant. The position, amplitude and frequency are continuously adjustable from the control panel. The table below provides a list of specifications for the unit.
Beam Position and Sweep
The electron beam gun uses electromagnets to position the beam in the crucible. The beam sweeper provides current for these electromagnets. Longitudinal and lateral position controls are capable of positioning the point of the beam impact anywhere in the crucible area. By changing the current in either one of the coils, the beam will traverse a straight line. The amplitude of the traverse is determined by the maximum and minimum currents delivered to the electromagnet. If the current is changed in both coils simultaneously, the beam can sweep over the entire area of the evaporant.
The wave shape provided by the sweeper is triangular; therefore, the current in the electromagnet changes from maximum to minimum at a constant rate. As a result, the electron beam spends equal amounts of time at all points along its traverse path. When the beam sweep is activated for both coils, the entire surface of the evaporant is uniformly heated.