Precise waveform measurement of long pulses
and macropulses up to several milliseconds
with minimal droop and noise
Bandwidth < 3Hz to 3MHz | Resolution < 1.5 µArms |
The ACCT is an evolution of the active transformer first proposed by Hereward in 1960. Compared to the Hereward transformer, the ACCT presents much lower noise, a DC offset of the output reduced to a very small value and excellent long-term stability. The sensor is built with a single winding, which requires only one wire pair between sensor and electronics; this allows much better EMI rejection when long cables are used. The electronics circuit is multistage, implementing the best low-noise operational amplifier available for this application.
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Two packaging type for the ACCT sensor |
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In-flange ACCT is mounted in the beam line. Short axial length, includes a ceramic gap vacuum-brazed to kovar. Does not require bellows, wall current bypass nor electromagnetic shield. Available from CF3“3/8 to CF8“ |
 In-air ACCT installation, over the vacuum chamber Requires installation of a “gap” to prevent the wall current from flowing through the ACCT aperture. The gap can be a brazed ceramic ring or an organic material O-ring depending on the vacuum requirements. Typical installations include bellows, a wall current bypass and an electromagnetic shield enclosing the ACCT completely. |
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Two versions of ACCT electronics |
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ACCT electronics with 3-selectable ranges In addition, 3 outputs available: 50Ω, 1MΩ and differential outputs DIN-rail mountable Power supply available
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ACCT electronics with single range Output to be read in high impedance device DIN-rail mountable Power supply available |
Full scale range From Output full scale Bandwidth Noise at 10mA FS Noise at 100mA FS | ±1mA to ±2A ±10V 3Hz to 1MHz (3MHz on option) ≈1.5µArms <5µArms |
