Principle
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.
Main features
- Full Scale Range from ±1 mA to ±2 A
- Single Range or 3 Selectable-Range
- Resolution ≤ 1.5 µArms
- Droop ≤ 2 %/ms
- Bandwidth from 3 Hz to 1 MHz (-3dB)
Downloads
Datasheets
User's manual
Papers
- ACCT shielding
- Implementation and validation of a beam-current transformer on a medical pulsed electron beam LINAC for FLASH-RT beam monitoring
- Dual beam-current transformer design for monitoring and reporting of electron ultra-high dose rate (FLASH) beam parameters
Technical Drawings
In-air
In-flange
- ACCT-CF3''3/8-22.2-40-UHV
- ACCT-CF4''1/2-34.9-40-UHV
- ACCT-CF4''1/2-38.0-40-UHV
- ACCT-CF6''-47.7-40-UHV
- ACCT-CF6''-60.4-40-UHV
- ACCT-CF6''3/4-96.0-40-UHV
- ACCT-CF8''-96.0-40-UHV
- ACCT-CF10''-147.6-40-UHV
- ACCT-CF12''-198.4-40-UHV
Current price list
Two packaging type for the ACCT sensor
In-flange ACCT
- In-flange ACCT is mounted in the beam line.
- Short axial length (40 mm), 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“
- Material AISI-304, 316LN on option
- Bakeable up to 185°C
- UHV compatible
In-air ACCT
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.
Two versions of ACCT electronics
ACCT electronics with 3-selectable ranges
- In addition, 3 outputs available: 50Ω, 1MΩ and differential outputs
- DIN-rail mountable
- Power supply available
ACCT electronics with single range
- Output to be read in high impedance device
- DIN-rail mountable
- Power supply available
Latest options available
Low-noise option
- Option to reduce ACCT resolution ≤ 0.5 µArms
- A second core is added in the sensor head, dimensions must be confirmed with Bergoz Instrumentation
- Electronics remain unchanged
- For more information about performances, see datasheet
3M option
- ACCT bandwidth extended to 3 MHz (-3dB) corresponding to a ~120 ns rise time (10%-90%)
- Sensor cable up to 7m (Above 7 meters overshoot may appear and rise time may increase)