• Keine Ergebnisse gefunden

Parallel Magnet Trimming C H Gough

N/A
N/A
Protected

Academic year: 2022

Aktie "Parallel Magnet Trimming C H Gough"

Copied!
6
0
0

Wird geladen.... (Jetzt Volltext ansehen)

Volltext

(1)

Parallel Magnet Trimming

C H Gough

Introduction

This Note is one of a series, documenting the development of the five Storage Ring Kicker systems for the SLS. The pulser current was found to depend upon which magnet was used. The magnet reactances were carefully measured [1], and to a good approximation, the inductances were identical, but the resistances varied in inverse proportion to the DC resistances of the metallised ceramic chamber.

This Note explores this situation using Pspice simulations. The goal is to keep identical pulsers, with the different magnets trimmed to be reasonably identical.

Basic Circuit

The magnet can be modelled as the primary of a transformer, with the metallised ceramic chamber as the secondary, as shown in Fig.1. The coupling and secondary inductance is scaled by a factor (62mm/104mm) which comes from the mechanical drawing in the Appendix.

Fig.1 Basic circuit.

The circuit of Fig.1 matches the inductance and resistance measurements up to 100kHz.

The non-linear CORE model of Pspice gives access to the magnetic field information, if used in the time domain. The CORE model is set with the area and gap of the magnet. A feature of this model is that coupling from the coil to the core scales the inductance also. Since the gap is large, the linearity is assumed perfect.

(2)

Fig.2 Basic circuit with CORE model.

Parallel Trimming

Comparisons are made between two different magnets, with parallel resistive and series resistive trimming of the magnet, using the circuit of Fig.3. The pulser circuit is indicative of a real circuit.

(3)

Fig.3 Comparison between two circuits that are identical, except for a 10% difference in the secondary resistance.

The matching of the currents and magnetic fields to tens of parts per million was possible. To evaluate the effect of component tolerances, various values of resistance were tried and the results are shown in Table 1.

R52

Reference Circuit

R53

Trial Circuit

B Matching for 1% change in R53

Current Matching for 1%

change in R53

10 8.225 <630ppm <1210ppm

50 24.05 <230ppm <430ppm

250 39.15 <160ppm <310ppm

Table 1. Sensitivities for parallel trimming resistors.

Series Trimming

In contrast to parallel trimming, series trimming is relatively poor performance, giving field matching to within a few parts per thousand only. Fig.4a-b show typical results. The results were similar for series resistances around 10m as well (the results are not shown).

(4)

Fig.4a Effect on magnetic field matching of varying series resistance 100, 200, 300, 400 and 500m against 100m in the reference circuit (4m represents 0.4%).

Fig.4b As for Fig.4a, but for proportional current difference (10mA represents 1%).

(5)

Conclusions

Contrary to all expectations, it is possible with simple resistive trimming to match the magnetic fields to an arbitrarily low value, with +/-10% variation of the resisitivity of the metallised ceramic chamber. This matched condition corresponds also to the minimum for the pulser current matching.

References

"SR Kicker Inductance Measurements", C H Gough, 1 October 2000 Appendix 1

Cross-Section of Magnet

Appendix 2

Non-Symmetric Coupling

With a standard transformer, the primary and secondary current each give magnetic flux, and there is coupled flux between the two circuits. The present situation is unusual because one circuit is "immersed" in the field of the other in a large volume with r=1.

In the extreme case that the secondary is small with respect to the vertical gap, the primary flux couples to it in proportion the secondary area, but the secondary flux is highly localised and may not couple to the primary; in other words, the coupling matrix Mij is asymmetric.

Appendix 3 - to be finished later

In the frequency domain, the impedance of a transformer is given by:

(6)

where : Z11 is the total loop impedance on the primary Z22 is the total loop impedance on the secondary M is the mutual inductance

The admittance is given by:

where : Y11 is the total loop admittance on the primary Y22 is the total loop admittance on the secondary M is the mutual inductance

Referenzen

ÄHNLICHE DOKUMENTE

But when man came along and changed the landscape, the closed landscape of the valleys became open spaces, and in some countries the valley sides and uplands

Concerning engine types, we assume that the energy required for the propulsion of the mining and transport vessels is generated by the ship’s main engine

Effects of electrokinetic phenomena on bacterial deposition monitored by quartz crystal microbalance with dissipation

Note 7 found that parallel resistance trimming of the magnets was highly effective to compensate for the different chamber resistances.. This Note finalises the choice of

By using the first section like a trombone between two test fixtures, the inductance and delay time could be found for different line lengths

Deputy Prime Minister Bülent Arınç said on 4 April that the strong support for the Justice and Development Party (AKP) in the March 30 local elections is a crystal clear sign

In a general language dictionary with text production as a function the obligatory search zone structure for collocations and their treatment could include at least one

&#34;Community Medicine&#34; aufgebaut. Ein Eckpfeiler dieses Schwerpunktes ist die Integration der Problemstellungen der Lehre, Forschung und medizinischen Versorgung.