Internship for young academic teachers (CAS/36/POKL) CERN X-XII 2014 Zuzanna Krawczyk This work has...
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Internship for young academic teachers (CAS/36/POKL) CERN X-XII 2014 Zuzanna Krawczyk This work has been supported by the European Union in the framework of European Social Fund through the Warsaw University of Technology Development Programme.
Internship for young academic teachers (CAS/36/POKL) CERN X-XII 2014 Zuzanna Krawczyk This work has been supported by the European Union in the framework
Internship for young academic teachers (CAS/36/POKL) CERN X-XII
2014 Zuzanna Krawczyk This work has been supported by the European
Union in the framework of European Social Fund through the Warsaw
University of Technology Development Programme.
Slide 2
Agenda Simulations of a new Short Waveguide Coupler The need of
a new coupler design The ShoCo design process ShoCo prototype
Estimation of the coupling coefficient and internal cell resonant
frequencies of multicell cavities on the basis of the equivalent
circuit model Parallel equivalent circuit model Corresponding field
simulations 2 cells case
Slide 3
Short waveguide coupler
Slide 4
The current solution T-type Coupler The weight: 111kg The
dimensions: 811x584.2x146.05[mm] Adjustable part: short circuit The
T-type coupler connected to a PIMS cavity
Slide 5
Need for more compact design
Slide 6
ShoCo Short Coupler Weight: 4.12kg Sizes: 160x50x310mm
Adjustable parts: Big plungers diameter of 36mm Small tuners
diameter of 20 mm The antenna
Slide 7
Types of simulation ShoCo with connected cavity Eigenmode
solution Symmetry Simulation time: 20 min Number of elements: 30000
Estimation of parameter cavity vaacum cavity iris ShoCo The
antenna
Slide 8
Types of simulation ShoCo with T-coupler Solution type: driven
modal, Network Analysis (S-parameters) Simulation time: 1-2 min
Number of elements: 7500 Estimation of S parameters T-coupler ShoCo
coupler Short circuit Port 1 Port 2
Slide 9
Position of the elements
Slide 10
Big plungers
Slide 11
Small tuners Just for the case when the initial coupling (big
plungers fully out) is not sufficient.
Slide 12
The prototype The prototype of the ShoCo connected to the PIMS
cavity
Slide 13
Results + cavity-to-waveguide coupling adjustable as desired -
resonant frequency of the center cell strongly modified (~1MHz)
=> strong change of the field distribution inside the cavity
(+/- 12% flatness error) => modification of the coupler is
needed
Slide 14
Equivalent circuit for Resonant Coupled Structures
Slide 15
Equivalent circuit model We described resonant coupled
structure with an equivalent circuit model, where each structure is
represented by a parallel RLC circuit. k1 first order coupling k2
second order coupling R,L,C lumped parameters: resistance,
inductance, capacitance In current which goes through the inductor
n
Slide 16
Equations for the circuit in terms of k,Q, ZL and modes
frequencies
Slide 17
Equations transformed to eigensystem form A matrix
Slide 18
2 - cells model k 1 -? f 01 -? f 02 -? f M01,f M02, voltages
Unknowns: internal frequencies of cells and coupling
coefficient:
Slide 19
HFSS field simulations Model of two cells in the eigenmode
solution type was set up. To speed up the simulation 30% of the
cavities rings was modelled Both cavities were modelled with tuning
rings Obtained: mode frequencies
Slide 20
The procedure Detune the first cell (0- 50mm, step 1mm) with
second tuner in the position: 0mm 10mm 20mm Observation: The
minimal difference between the two mode frequencies when both
tuners are at the same position (both cavities are the same)
Slide 21
Comparison of the changes in mode frequency by detuning the
first cell in HFSS simulation and by changing the internal
frequency of the first cell in internal circuit simulation
Slide 22
Setup of the parameters
Slide 23
Relation between two mode frequencies for different coupling
coefficient : - measurements from HFSS simulation (change of the
first tuner from 0 to 50mm) Solid lines RLC simulation, with change
of internal frequency of first cavity from 362.7 to 390 MHz
Slide 24
Results For 2 cells cavities procedure has been established
Precision: ~1% of coupling factor For 3 cells investigation is
ongoing