Multipactor in Low Pressure Gas and in ... - of Richard Udiljak

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3.2.4 Key findings . . . . . . . . . . . . . . . . . . . . . 52 4 Multipactor in irises 59 4.1 Model and approximations . . . . . . . . . . . . . . . . . . 60 4.2 Multipactor regions . . . . . . . . . . . . . . . . . . . . . . 64 4.3 Comparison with experiments . . . . . . . . . . . . . . . . 65 4.4 Main results . . . . . . . . . . . . . . . . . . . . . . . . . . 67 5 Multipactor in coaxial lines 69 5.1 Analytical study . . . . . . . . . . . . . . . . . . . . . . . 70 5.1.1 Model . . . . . . . . . . . . . . . . . . . . . . . . . 70 5.1.2 Multipactor resonance theory . . . . . . . . . . . . 73 5.1.3 Main findings . . . . . . . . . . . . . . . . . . . . . 81 5.2 Particle-in-cell simulations . . . . . . . . . . . . . . . . . . 82 5.2.1 Numerical implementation . . . . . . . . . . . . . . 82 5.2.2 Simulations . . . . . . . . . . . . . . . . . . . . . . 83 5.2.3 Comparison with experiments . . . . . . . . . . . . 88 5.2.4 Main conclusions . . . . . . . . . . . . . . . . . . . 91 6 Detection of multipactor 93 6.1 Common Methods of Detection . . . . . . . . . . . . . . . 93 6.1.1 Global methods . . . . . . . . . . . . . . . . . . . . 94 6.1.2 Local methods . . . . . . . . . . . . . . . . . . . . 99 6.2 Detection using RF Power Modulation . . . . . . . . . . . 100 6.2.1 Single carrier . . . . . . . . . . . . . . . . . . . . . 105 6.2.2 Multicarrier . . . . . . . . . . . . . . . . . . . . . . 105 6.2.3 Main achievements . . . . . . . . . . . . . . . . . . 106 7 Conclusions and outlook 111 References 115 Included papers A–F 123 x
Acknowledgement I wish to thank Prof. Dan Anderson and Prof. Mietek Lisak for accepting me as a PhD student and for guidance and support in my daily work. I also want to thank Prof. Vladimir Semenov at the Institute of Applied Physics in Nizhny Novgorod, Russia, for fruitful discussions and for his patience with all my questions. Thank you Prof. Lars Eliasson, Director at the Institute of Space Research in Kiruna, for providing both financial and moral support making my PhD candidate appointment possible. A very warm thank you also to Jerome Puech for many interesting discussions about space related microwave problems and to his employer, Centre National d’ Études Spatiales, for financial support. Thanks to my friends in Toulouse and especially Dr. Omar Houbloss and Raquel Rodriguez. I thank my fellow members of the National Graduate School of Space Technology and my colleagues at Chalmers and especially Dr. Pontus Johannisson, Dr. Ulf Jordan and Dr. Lukasz Wolf for beneficial discussions and lots of support with Linux and LaTex. Many thanks also to our secretary Monica Hansen for guiding me through the administrative jungle. I want to thank my dear mother, Monica, for encouraging and supporting me and my family when 24 hours a day wasn’t enough and my father, brother and sisters for believing in me. I am also grateful to my unofficial mentors: my father-in-law Lars-Göran Östling, my friends Jörgen Otbäck and Anders Wilhelmsson, and my brother-in-law Nicklas Östling. Most of all I thank my wife Malin and our daughters Janina and Lizette for encouragement and support during this time. xi
Page 1 and 2: Thesis for the degree of Doctor of
Page 3: Multipactor in Low Pressure Gas and
Page 6 and 7: Conference contributions by the aut
Page 8 and 9: viii
Page 12 and 13: xii
Page 14 and 15: xiv
Page 16 and 17: addition, it is difficult to make c
Page 18 and 19: numerical study of the phenomenon i
Page 20 and 21: to physically damage microwave comp
Page 22 and 23: odd positive integer (N = 1,3,5...)
Page 24 and 25: σ se [−] 2.5 2 1.5 1 0.5 W 1 W m
Page 26 and 27: Voltage [V] 10 4 10 3 10 2 10 0 N=1
Page 28 and 29: even though it may be sufficient fr
Page 30 and 31: where φL and φR are the left and
Page 32 and 33: (cf. Fig. 2.7). When taking the env
Page 34 and 35: 2.1.4 Methods of suppression Many o
Page 36 and 37: Noise (dBm) Power #1 (dBm) Match #1
Page 38 and 39: andom spread in emission velocities
Page 40 and 41: Figure 2.12: Multipactor experiment
Page 42 and 43: where kn is a factor determining th
Page 44 and 45: allows for another design margin, w
Page 46 and 47: Boundary function Method One of the
Page 48 and 49: carriers, because the NLSQ method r
Page 50 and 51: multipactor discharge. Using a Mont
Page 52 and 53: the assumption of a constant ratio
Page 54 and 55: Voltage (V) 10 3 10 2 10 1 10 −2
Page 56 and 57: 3.1.3 Main results The main result
Page 58 and 59: lytical model is obviously needed.
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where 〈vt 2 〉 represents the av
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these quantities in the range from
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analytical. Attempts were made to f
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only model, the inclusion of ionisa
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Normalised Voltage 1.1 1.05 1 0.95
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Voltage [V] 10 3 10 0 µ=0 µ=0.75
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Chapter 4 Multipactor in irises A c
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h l Figure 4.1: The geometry used i
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N e /N 0 [−] 3 2.5 2 1.5 1 Multip
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to compensate for electron losses i
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4.4 Main results This analysis has
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support for the qualitative analyti
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where R(t) is the average position,
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where d stands for the gap width, V
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there are different oscillatory vel
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Phase [degrees] 60 50 40 30 20 10
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G 100 90 80 70 60 50 40 30 20 10 0
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possible for quite large Ro/Ri-valu
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upper right region of the figures,
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σse,max the zones become wider and
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G 50 45 40 35 30 25 20 15 10 5 0.2
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creasing ratio Ri/Ro was observed.
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Chapter 6 Detection of multipactor
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Amplitude of acceleration [Gm/s 2 ]
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tipactor events that are short-live
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software and the time evolution of
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ditional test sample, a resonant ca
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the FFT. It was concluded that ther
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6.2.1 Single carrier When using the
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Reference signal generator Phase co
Page 123 and 124:
Amplitude [A.U.] 2.5 2 1.5 1 0.5 De
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Chapter 7 Conclusions and outlook T
Page 127 and 128:
tioned there were multipactor in no
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References [1] W. Henneberg, R. Ort
Page 131 and 132:
[27] A. Ruiz et al, “Ti, V, and C
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[51] D. Wolk, D. Schmitt, and T. Sc
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[75] R. Udiljak, Multipactor in low
Page 137:
Included papers A-F 123
Page 141:
Paper B R. Udiljak, D. Anderson, M.
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Paper D R. Udiljak, D. Anderson, M.
Page 149:
Paper F V. E. Semenov, N. Zharova,
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