IBIC2013 - List of Authors (Kalinin, A.)

Paper

Title

Page

Novel Pickup for Bunch Arrival Time Monitor

170

A. Kalinin
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

For an optical-modulator-based BAM, main parameter of the pickup output signal is slope steepness. We suggest a novel pickup with flat thin electrodes in a transverse gap. Increasing the electrode width makes the steepness greater in the same extent as the signal increases. For a given width, reducing the electrode thickness allows to reach ultimate steepness. Wave processes in the pickup were investigated on a large scale model, using the technique described in *. The DESY 40GHz button pickup was used as a reference. It is shown that steepness of the flat electrode pickup can be achieved two times greater. It is also shown that a BAM electrode pickup has a remarkable feature: the steepness does not depend on electrode sizes, if the ratio w/G (a flat electrode pickup, the width and gap length) or d/D (a button pickup, the diameters) is kept constant. This makes pickup bandwidth that is of the order of c over 2G or 2D, a free parameter. For flat electrode pickup, the steepness can be kept as high with transition to a more practical bandwidth 20GHz. The investigation results are the base for a final pickup optimisation using electrodynamic simulation.
* A. Kalinin, “Pickup Electrode Electrodynamics Investigation”, WEPC26, this conference

Poster MOPC42 [0.549 MB]

WEPC26

Pickup Electrode Electrodynamics Investigation

742

A. Kalinin
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Waves induced in a pickup by beam were investigated on a large scale model, using 10ps step in coaxial line as beam, and a differentiating capacitive probe. The probe signal was observed at 20GHz oscilloscope. In each of the front and rear transverse gaps between pickup electrode and wall (button pickup), a shorter-than-gap bunch excites a ‘plain-wave’ packet which length is of the order of gap length over c. Two packets are spaced by electrode length over c. The packets propagate along the electrode to a coaxial connector. At this low impedance common point each of the packets partially reflects back and partially passes into the opposite gap. The voltage appearing on the impedance excites two TEM-wave packets: one propagates backwards, another one propagates forward through connector. The connector output is sum of two such packets spaced the same as two incident packets. The packets propagating backwards reflect from the electrode open end, come back to the summing point and generate output in similar way. The same processes occur in a pickup with single gap electrodes (stripline pickup). This phenomenological picture can be used as a guide in pickup design and simulation.

Poster WEPC26 [0.647 MB]

Paper	Title	Page
MOPC42	Novel Pickup for Bunch Arrival Time Monitor	170
	A. Kalinin STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	For an optical-modulator-based BAM, main parameter of the pickup output signal is slope steepness. We suggest a novel pickup with flat thin electrodes in a transverse gap. Increasing the electrode width makes the steepness greater in the same extent as the signal increases. For a given width, reducing the electrode thickness allows to reach ultimate steepness. Wave processes in the pickup were investigated on a large scale model, using the technique described in . The DESY 40GHz button pickup was used as a reference. It is shown that steepness of the flat electrode pickup can be achieved two times greater. It is also shown that a BAM electrode pickup has a remarkable feature: the steepness does not depend on electrode sizes, if the ratio w/G (a flat electrode pickup, the width and gap length) or d/D (a button pickup, the diameters) is kept constant. This makes pickup bandwidth that is of the order of c over 2G or 2D, a free parameter. For flat electrode pickup, the steepness can be kept as high with transition to a more practical bandwidth 20GHz. The investigation results are the base for a final pickup optimisation using electrodynamic simulation. A. Kalinin, “Pickup Electrode Electrodynamics Investigation”, WEPC26, this conference
	Poster MOPC42 [0.549 MB]

WEPC26	Pickup Electrode Electrodynamics Investigation	742
	A. Kalinin STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Waves induced in a pickup by beam were investigated on a large scale model, using 10ps step in coaxial line as beam, and a differentiating capacitive probe. The probe signal was observed at 20GHz oscilloscope. In each of the front and rear transverse gaps between pickup electrode and wall (button pickup), a shorter-than-gap bunch excites a ‘plain-wave’ packet which length is of the order of gap length over c. Two packets are spaced by electrode length over c. The packets propagate along the electrode to a coaxial connector. At this low impedance common point each of the packets partially reflects back and partially passes into the opposite gap. The voltage appearing on the impedance excites two TEM-wave packets: one propagates backwards, another one propagates forward through connector. The connector output is sum of two such packets spaced the same as two incident packets. The packets propagating backwards reflect from the electrode open end, come back to the summing point and generate output in similar way. The same processes occur in a pickup with single gap electrodes (stripline pickup). This phenomenological picture can be used as a guide in pickup design and simulation.
	Poster WEPC26 [0.647 MB]