DOCSLIB.ORG

RF Power Generation I

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

RF Power Generation I

Gridded Tubes and Solid-state Amplifiers

Professor R.G. Carter

Engineering Department, Lancaster University, U.K. and
The Cockcroft Institute of Accelerator Science and Technology

Overview

• High power RF sources required for all accelerators > 20 MeV • Amplifiers are needed for control of amplitude and phase • RF power output

– 10 kW to 2 MW cw – 100 kW to 150 MW pulsed

• Frequency range

– 50 MHz to 50 GHz

• Capital and operating cost is affected by

– Lifetime cost of the amplifier – Efficiency (electricity consumption) – Gain (number of stages in the RF amplifier chain) – Size and weight (space required)

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 2

General principles

• RF systems

– RF sources extract RF power from high charge, low energy electron bunches

– RF transmission components
(couplers, windows, circulators etc.) convey the RF power from the source to the accelerator

– RF accelerating structures use the
RF power to accelerate low charge bunches to high energies

P P PRF out  Heat

  • RF in
  • DC in

  • P
  • P

  • RF out
  • RF out

• RF sources

Efficiency

P P
P

  • DC in
  • RF in
  • DC in

– Size must be small compared with the distance an electron moves in one RF cycle

P

RF out

Gain dB 10log

 

10

– Energy not extracted as RF must be disposed of as heat

P

RF in

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 3

RF Source Technologies

  • • Vacuum tubes
  • • Solid state

  • – High electron mobility
  • – Wide band-gap materials (Si,

GaAs, GaN, SiC, diamond)

– Low carrier mobility – Small size
– Large size – High voltage

– High current

• Tube types

– Low voltage
– Gridded Tubes (Tetrodes)

– Inductive output tubes (IOTs) – Klystrons

• Single Transistors

– Si LDMOS: 450 W at 860 MHz – GaN: 180W at 3.5 GHz; 80 W at
9.6 GHz
– Gyrotrons – Magnetrons (locked oscillators)
– GaAs: 65 W at 14 GHz

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 4

SOLEIL 352 MHz amplifier

•••

Output power 180 kW 726 × 315 modules in 4 towers 2 × Si LDMOS transistors per module in push-pull

••

53dB Gain Overall efficiency ~ 50%

Images courtesy of Synchrotron SOLEIL

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 5

Solid State

  • Advantages
  • Disadvantages

• No warm-up time • High reliability • Low voltage (<100 V) • Air cooling
• Complexity • Losses in combiners • Failed transistors must be isolated • Electrically fragile

  • • High I2R losses
  • • Low maintenance

  • • High stability
  • • Low efficiency

• Graceful degradation

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 6

Tetrode construction

Cathode

Control grid

Screen grid

Anode

Images courtesy of e2v technologies

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 7

Tetrode characteristics

n
Vg 2

Va

Ia C Vg1





2 a

• n = 1.5 to 2.5 • DC bias conditions relative to cathode

– Anode voltage positive – Screen grid positive (~ 10% Va) – Control grid negative

• Anode current depends

– Strongly on control grid voltage – Weakly on anode voltage

• In practice Anode is at earth potential

Graph courtesy of Siemens AG

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 8

Tetrode common grid connection

• Grids held at RF ground isolate input from output

• Input is coaxial • Anode resonant circuit is a reentrant coaxial cavity

• Output is capacitively or inductively coupled

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 9

Class B operation

•

Control grid bias set so that anode current is zero when no RF input

••

Conduction angle = 180° Resonant circuit makes anode voltage variation sinusoidal

2

I2 I0

V2  0.9V0

••

Va > Vg2 always Theoretical efficiency ~70%

1
0.9

P I2V2
I0V0

2

  • 2
  • 4

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 10

Classes of amplification

Class A
Conduction angle
Maximum theoretical efficiency

  • Gain increasing
  • Harmonics

increasing

  • 360°
  • 50%

AB B
180° – 360° 180°
50% - 78% 78%

  • C
  • < 180°
  • 78% - 100%

• All classes apart from A must have a resonant load and are therefore narrow band amplifiers

• Class AB or B usually used for accelerators

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 11

CERN 62 kW 200 MHz amplifier

• RS 2058 CJ tetrode

– Siemens (now Thales)

• Class AB operation

– Assume Class B for illustration

• Efficiency - 64%

Photo courtesy of e2v technologies
Photo courtesy of CERN

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 12

Tetrode amplifier design

•••

Choose Va = 10 kV, Vg2 = 900 V

Choose Va = 1.5 kV when Ia = Ipk

Theoretical Class B efficiency

0.85

th

 67 %
4

62

P

 92.5 kW

0

0.67

88.6

I0

 9.25 A
10

••

Assume Ipk = 4I0 (theoretically π I0)

Ipk  37 A

and draw the load line

Graph courtesy of Siemens AG

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 13

Calculation of performance (1)

Angle

  • Va
  • Ia

•

Find Va and Ia in 15° steps

  • (deg) (kV)
  • (A)

Va V0 V2 cos

  • 0
  • 1.5

1.8 2.6 4.0 5.7 7.8
10.0
37 35 30 20 8.5
3
15 30 45 60 75 90

•

Find I0 and I1 by numerical Fourier analysis

1

P V2I2

P I0V0

2

0

2

0

P

2

V2

 

R2

V0 = V2 = P0 =

10.0 kV
8.5 kV 96 kW
I0 = I2 =

  • 9.6
  • A

P

0

I2

16.2 A

••

Initial estimate of Ipk/I0 was too high Iterate for self-consistent solution

P2 = R2 =
69 kW

  • 72
  • %
  • 524

1

  • I  (0.5I I
  • I
  • I
  • I
  • I

)
0

a0 a15 a30 a45 a60 a75

12

1

I  (I 1.93I a0

  • 1.73I
  • 1.41I
  • I

a45 a60
 0.52I

)
2

  • a15
  • a30
  • a75

12

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 14

Calculation of performance (2)

• Grounded grid operation

  • Calculated
  • Measured

10

V0 I0

  • 10
  • kV

A

V  80  240  320 V

1

9.6 69
9.4

P2 P1

Gain

  • 62
  • kW

kW dB %

I1 I2 Ig1 RF I2

2.6 14.3 72
1.8

V

1

15.4 64

R   20 

1

I1

1

P V I   2.59 kW

  • 1
  • 1 1

2

W.Herdrich and H.P. Kindermann, “RF power amplifier for the CERN SPS operating as LEP injector”,

 

P

2

 

P

  • Gain 10log10
  • 14.3 dB

CERN SPS/85-32, PAC 1985

1

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 15

Tetrode input and output circuits

• Input and output circuits are coaxial

b

 

Z0  60ln


 

a

 

• a = inner diameter, b = outer diameter

• Characteristic impedance is very low (~ few ohms)

• Careful design of matching is essential

R  20  Xkg1  5.7 

in

Rout  524  Xg 2a  20 

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 16

Cooling and protection

  • Anode Cooling
  • Protection

•

••

Air

••••

Coolant flow

  • Water
  • Coolant temperature

  • Tube temperature
  • Vapour phase

Anode, screen and grid overcurrent

•

Anode voltage (fast)

Switch-on sequence

••

Heater voltage Grid bias
(pause)

•••

Anode voltage Screen grid voltage RF drive

Image courtesy of e2v technologies

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 17

Combining tetrode amplifiers

CERN SPS 200 MHz, 500 kW, amplifiers

Photo courtesy of CERN

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 18

Tetrode limitations

•••

Cathode current density Anode dissipation Transit time

•••

Anode length << λ0 Anode diameter RF screen grid dissipation

Thales Diacrode® reduces this

–

Va least when Ia greatest

•

Voltage breakdown

Image courtesy of Thales Electron Devices

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 19

Inductive output tube (IOT)

Differences from tetrode

• Electron flow axial

– Requires axial magnetic field to prevent beam spreading

• Anode voltage is constant

– Electron velocity is high

• Bunched beam induces current in output cavity

• Separate electron collector

– Large collection area

• Increased isolation between input and output

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 20

IOT output gap interaction

• Beam current class AB or B like a tetrode • At resonance electric field in the gap is maximum retarding when bunch is in the centre of the gap

• Effective gap voltage reduced by transit time effects

• Effective gap voltage less than ~0.9V0 to allow electrons to pass to the collector

• Theoretical efficiency ~ 70%

1

4

P I2Vg,eff  0.9I0V0

2

2

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 21

UHF IOT for TV broadcasting

Frequency Power
470 - 810 MHz 64 kW
Beam voltage Beam current Gain
32 kV 3.35 A 23 dB

  • Efficiency
  • 60%

Photos courtesy of e2v technologies

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 22

Examples of IOTs for accelerators

Frequency Beam voltage Beam current RF output power Efficiency
267 67
500 1300 MHz 40 3.5 90
25 1.0 16 kV

  • A
  • 6.0

280 70 kW

  • %
  • >65 62

  • >22 21
  • Gain
  • 22
  • dB

  • June 2010
  • CAS RF for Accelerators, Ebeltoft
  • 23

Recommended publications
  • Comparative Overview of Inductive Output Tubes

    Comparative Overview of Inductive Output Tubes

    ! ESS AD Technical Note ! ESS/AD/0033 ! ! ! ! ! ! !!!!!!!!!! ! !!!Accelerator Division ! ! ! ! ! ! ! ! ! ! Comparative Overview of Inductive Output Tubes Rihua Zeng, Anders J. Johansson, Karin Rathsman and Stephen Molloy Influence of the Droop and Ripple of Modulator onRebecca Klystron SeviourOutput June 2011 23 February 2012 I. Introduction An IOT is a beam driven vacuum electronic RF amplifier. This document represents a comparative overview of the Inductive Output Tube (IOT). Starting with an overview of the IOT, we progress to a comparative discussion of the IOT relative to other RF amplifiers, discussing the advantages and limitations within the frame work of the RF amplifier requirements for the ESS. A discussion on the current state of the art in IOTs is presented along with the status of research programmes to develop 352MHz and 704MHz IOT’s. II. Background The Inductive Output Tube (IOT) RF amplifier was first proposed by Haeff in 1938, but not really developed into a working technology until the 1980s. Although primarily developed for the television transmitters, IOTs have been, and currently are, used on a number of international high- powered particle accelerators, such as; Diamond, LANSCE, and CERN. This has created a precedence and expertise in their use for accelerator applications. IOTs are a modified form of conventional coaxial gridded tubes, similar to the tetrode, although modified towards a linear beam structure device, similar to a Klystron. This hybrid construct is sometimes described as a cross between a klystron and a triode, hence Eimacs trade name for IOTs, the Klystrode. A schematic of an IOT, taken from [1], is shown in Figure 1.
  • ABBREVIATIONS EBU Technical Review

    ABBREVIATIONS EBU Technical Review

    ABBREVIATIONS EBU Technical Review AbbreviationsLast updated: January 2012 720i 720 lines, interlaced scan ACATS Advisory Committee on Advanced Television 720p/50 High-definition progressively-scanned TV format Systems (USA) of 1280 x 720 pixels at 50 frames per second ACELP (MPEG-4) A Code-Excited Linear Prediction 1080i/25 High-definition interlaced TV format of ACK ACKnowledgement 1920 x 1080 pixels at 25 frames per second, i.e. ACLR Adjacent Channel Leakage Ratio 50 fields (half frames) every second ACM Adaptive Coding and Modulation 1080p/25 High-definition progressively-scanned TV format ACS Adjacent Channel Selectivity of 1920 x 1080 pixels at 25 frames per second ACT Association of Commercial Television in 1080p/50 High-definition progressively-scanned TV format Europe of 1920 x 1080 pixels at 50 frames per second http://www.acte.be 1080p/60 High-definition progressively-scanned TV format ACTS Advanced Communications Technologies and of 1920 x 1080 pixels at 60 frames per second Services AD Analogue-to-Digital AD Anno Domini (after the birth of Jesus of Nazareth) 21CN BT’s 21st Century Network AD Approved Document 2k COFDM transmission mode with around 2000 AD Audio Description carriers ADC Analogue-to-Digital Converter 3DTV 3-Dimension Television ADIP ADress In Pre-groove 3G 3rd Generation mobile communications ADM (ATM) Add/Drop Multiplexer 4G 4th Generation mobile communications ADPCM Adaptive Differential Pulse Code Modulation 3GPP 3rd Generation Partnership Project ADR Automatic Dialogue Replacement 3GPP2 3rd Generation Partnership
  • 3D Modeling, Analysis, and Design of a Traveling-Wave Tube

    3D Modeling, Analysis, and Design of a Traveling-Wave Tube

    3D MODELING, ANALYSIS, AND DESIGN OF A TRAVELING-WAVE TUBE USING A MODIFIED RING-BAR STRUCTURE WITH RECTANGULAR TRANSMISSION LINES GEOMETRY by SADIQ ALI ALHUWAIDI B.S., University of Colorado, Boulder, 2011 M.S., University of Colorado, Colorado Springs, 2014 A dissertation submitted to the Graduate Faculty of the University of Colorado Colorado Springs in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Electrical and Computer Engineering 2017 © 2017 SADIQ ALI ALHUWAIDI ALL RIGHTS RESERVED This dissertation for the Doctor of Philosophy degree by Sadiq Ali Alhuwaidi has been approved for the Department of Electrical and Computer Engineering by Heather Song, Chair T.S. Kalkur Charlie Wang John Lindsey Zbigniew Celinski Date 12/05/2017 ii Alhuwaidi, Sadiq Ali (Ph.D. Engineering - Electrical Engineering) 3D Modeling, Analysis, and Design of a Traveling-Wave Tube Using a Modified Ring- Bar Structure with Rectangular Transmission Lines Geometry Dissertation directed by Associate Professor Heather Song. ABSTRACT A novel slow-wave structure of the traveling-wave tube consisting of rings and rectangular coupled transmission lines is modeled, analyzed, and designed in the frequency range of 1.89-2.72 GHz. The dispersion and interaction impedance characteristics are investigated using High Frequency Structure Simulator, HFSS, and a power run is carried out using Finite-Difference Time-Domain (FDTD) code, VSim. The performance of the design providing a better output power, gain, bandwidth, and efficiency is compared to the conventional and existing designs by implementing cold- and hot-test simulations. In addition, an electron gun and periodic permanent magnet, PPM, is designed using EGUN code and ANSYS Maxwell, respectively.
  • Use Style: Paper Title

    Use Style: Paper Title

    Fast Opening Switch Approach for High-Voltage Vacuum Tube Protection Application Wolfhard Merz1, and Monty Grimes2 1DESY, Hamburg, Germany, [email protected] 2Behlke Power Electronics LLC, Billerica, MA, USA, [email protected] Abstract as well. Pulsed mode operation is characterized by 1 Hz repetition rate and duty factor ranging from 0.1 to 0.5 The operation of high-power, high-frequency vacuum tubes respectively. requires an appropriate protection method to avoid significant damages during arcing. Fast closing switches like spark gaps, thyratrons, ignitrons and semiconductors acting as charge- B. Preceding Closing Switch Protection diverting bypass switches are the most commonly used protection A preceding installation for operating a prototype of the method. These “crowbar” switches cause hard transient IOT within a Cryogenic Module Test Bench (CMTB) was conditions for all subcomponents involved and usually result in a accomplished by the application of the classic closing switch significant post-fault recovery period. The availability of fast approach by means of Light Triggered Thyristors (LTT) [1]. high-voltage semiconductor devices, with flexible on/off control For sufficient margin in case of arcing, additional current function, makes opening switch topologies possible and attractive limiting resistors had to be applied. The simplified topology is to improve this situation. This paper describes a circuit topology given in Fig. 1. The protection efficiency of this previous test to protect an Inductive Output Tube which is expected to operate configuration will be compared with the new opening switch within RF subsystems for accelerator applications. The topology approach. The general topology operating an opening switch as is characterized by using a commercial available high voltage MOSFET switch with direct liquid cooling and completed with a series connected device replacing the closing switch is given essential snubber extensions.
  • LLRF9 Low-Level RF Controller

    LLRF9 Low-Level RF Controller

    LLRF9 Low-Level RF Controller Technical User Manual Author: Revision: Dmitry Teytelman 1.3 March 13, 2019 Copyright © Dimtel, Inc., 2014{2017. All rights reserved. Dimtel, Inc. 2059 Camden Avenue, Suite 136 San Jose, CA 95124 Phone: +1 650 862 8147 Fax: +1 603 218 6669 www.dimtel.com CONTENTS Contents 1 Regulatory Compliance Information3 2 Introduction4 3 Installation and Maintenance6 3.1 Rack Mounting and Ventilation Requirements.........6 3.2 AC Power Connection......................6 3.3 IOC Setup.............................6 3.4 Intake Air Filter Maintenance..................9 4 Hardware 10 4.1 Overall topology......................... 10 4.2 LLRF4.6.............................. 11 4.3 RF input channels........................ 11 4.4 RF outputs............................ 12 4.5 LO signal generation....................... 12 4.5.1 500 MHz.......................... 12 4.5.2 476 MHz.......................... 14 4.5.3 204 MHz.......................... 14 4.6 Interlock subsystem........................ 14 4.7 Digital I/O............................ 15 4.8 Slow analog inputs........................ 15 4.9 Housekeeping........................... 16 5 Feedback 18 5.1 Cavity field control........................ 18 5.2 Setpoint profile.......................... 19 5.3 Tuner loop............................. 20 6 Acquisition and Diagnostics 22 6.1 Scalar acquisition......................... 22 6.2 Channel attributes........................ 22 6.2.1 Amplitude......................... 22 6.2.2 Phase........................... 23 6.3 Waveform acquisition....................... 24 6.4 Real-time Network Analyzer................... 24 1 of 41 CONTENTS 7 Interlocks 25 7.1 RF input interlocks........................ 26 7.2 Baseband ADC interlocks.................... 27 8 System configurations 28 8.1 One station, single cavity, single power source......... 29 8.2 One station, two cavities, single power source......... 29 8.3 Two stations, two cavities, two power sources........
  • High Power Radio Frequency Solid-State Amplifiers and Combiners for Particle Accelerators

    High Power Radio Frequency Solid-State Amplifiers and Combiners for Particle Accelerators

    Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1881 High Power Radio Frequency Solid-State Amplifiers and Combiners for Particle Accelerators From module to system design approach LONG HOANG ACTA UNIVERSITATIS UPSALIENSIS ISSN 1651-6214 ISBN 978-91-513-0818-0 UPPSALA urn:nbn:se:uu:diva-397500 2019 Dissertation presented at Uppsala University to be publicly examined in Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, Wednesday, 15 January 2020 at 09:15 for the degree of Doctor of Philosophy. The examination will be conducted in English. Faculty examiner: Professor Paul Tasker (School of Engineering, Cardiff University). Abstract Hoang, L. 2019. High Power Radio Frequency Solid-State Amplifiers and Combiners for Particle Accelerators. From module to system design approach. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1881. 98 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-513-0818-0. The rise of Big Science projects brings issues related to the energy consumption and the associated environmental impacts of such large-scale facilities. Therefore, environmentally- sustainable developments are undertaken towards the adoption of energy savings and improved energy-efficient approaches. The advent of the superconducting (SC) radio frequency (RF) accelerating cavity is bringing answers to these issues. Such superconducting RF (SRF) cavity is made of niobium that allows much higher accelerating gradients with a minimization of the energy consumption. The SC RF technology is increasingly used in many modern particle accelerators, including: the European Spallation Source (ESS), the X-ray Free Electron Laser (XFEL), the Linac Coherent Light Source (LCLS)-II and the proposed International Linear Collider (ILC).
  • Review of Available Power Sources

    Review of Available Power Sources

    Review of Available Power Sources Carl Beard CCLRC Daresbury Laboratory Keckwick Lane, Daresbury, Warrington WA4 4AD, UK Corresponding author: Carl Beard CCLRC Daresbury Laboratory Warrington WA4 4AD, UK Phone: +44 (0)1925 603588 FAX: +44 (0)1925 603124 e-mail: [email protected] ABSTRACT Klystrons and triodes have been the accepted choice for particle accelerators because they produce high power RF and offer high gain (60 dB) with efficiencies of ~50%. Although fairly new to the market, IOTs have become available at L-band frequencies and have maintained their high efficiency. The development of Superconducting RF at the L- band frequency allows IOTs to become the choice for future accelerator programs. Due to the operational nature of SRF technology in energy recovery mode, there is no longer the requirement for large amounts of RF power from single sources. This report reviews some of the developments in RF power sources suitable for ERLs. Keywords: Klystron, Inductive Output Tube, IOT, Power Sources, Radio Frequency. 1. KLYSTRONS Invented in the late 1930’s by the Varian brothers, Klystrons contain three separate sections, the gun region, the RF interaction region, and the collector (figure 1). A typical klystron would contain a thermionic gun, several RF cavities and a collector to retrieve the spent electrons. A DC electron beam is emitted from the gun, and in the absence of RF the electrons travel through the drift tube and would disperse in the collector. The electron beam is magnetically focused to counter the effect of space charge growth through the drift tube section.
  • 2011 IEEE International Vacuum Electronics Conference

    2011 IEEE International Vacuum Electronics Conference

    2011 IEEE International Vacuum Electronics Conference (IVEC 2011) Bangalore, Karnataka, India 21 – 24 February 2011 IEEE Catalog Number: CFP11VAM-PRT ISBN: 978-1-4244-8662-5 Contents Foreword ............................................................................................................................................. iii IVEC-2011 Organising Committees ..................................................................................................... v EDS Technical Committee on Vacuum Devices .................................................................................. vi Inaugural Session PL-1: Relativistic Effects in Microwave Vacuum Electronics .................................................... 1 Michael I. Petelin (Institute of Applied Physics, Nizhny Novgorod, Russia) Plenary Session–1 PL-2: Microwaves and Particle Accelerators: A Fundamental Link .......................................... 5 Swapan Chattopadhyay (Cockcroft Institute of Accelerator Science & Technology, UK) PL-3: Vacuum Electronics in India ............................................................................................... 7 Lalit Kumar (Microwave Tube R&D Centre, Bangalore, India) PL-4: Vacuum Electronic Sources for High Power Terahertz-Regime ..................................... 11 John Booske (University of Wisconsin-Madison, USA ) Session–1: Traveling-Wave Tubes 1.1: Design and Development of 2 to 3 Octave Band Helix Mini-TWTs ................................. 15 Tushar K. Ghosh, Anthony J. Challis, Anthony Tokeley, Michael
  • RF SYSTEMS WOLFGANG ANDERS Helmholtz-Zentrum Berlin for Materials and Energy Albert-Einstein-Str

    RF SYSTEMS WOLFGANG ANDERS Helmholtz-Zentrum Berlin for Materials and Energy Albert-Einstein-Str

    An Engineering Guide to Photoinjectors, T. Rao and D. H. Dowell, Eds. CHAPTER 10: RF SYSTEMS WOLFGANG ANDERS Helmholtz-Zentrum Berlin for Materials and Energy Albert-Einstein-Str. 15, D-12489 Berlin, Germany AXEL NEUMANN SRF Science and Technology/BESSY II Helmholtz-Zentrum Berlin for Materials and Energy Albert-Einstein-Str. 15, D-12489 Berlin, Germany Keywords RF Transmitters, Tetrode, Klystron, Solid State RF Amplifier, Modulators, Transmission Line, Circulator, Low-level RF, RF Control System, Fundamental Power Coupler, Waveguide Coupler, Coaxial Coupler, Higher-Order Mode Coupler Abstract The RF system is responsible for feeding adequate power to the injector with required phase and amplitude stability. The low level RF system provides the input for the high power amplifier and controls the phase and amplitude via feedback and feedforward loops. The high power RF amplifies the milliwatt level input to kilowatt/megawatt level. The first step in developing the high power RF system is to establish the power level and the tolerances required. In this chapter, we discuss the methods to determine these values followed by a description of the essential components, namely, the preamplifier, high power amplifier, transmission line, fundamental power couplers and higher order mode couplers. We describe major errors sources for field stability of the RF cavities such as frequency shift due to temperature fluctuation, Lorentz detuning, micro-phonics. We provide a sequence of steps to design and operate the LLRF a generic system with examples for controlling the LLRF. This chapter is subdivided into six sections: After an introduction, we discuss the essential aspects of the high power RF transmitters and transmission lines, the low-level RF (LLRF) system and the issues related to the fundamental- and higher order mode-couplers.
  • Revised Classification of Radio Subjects Used in National Bureau of Standards

    Revised Classification of Radio Subjects Used in National Bureau of Standards

    U. S. DEPARTMENT OF COMMERCE NATIONAL BUREAU OF STANDARDS WASHINGTON 1RPL-R29 Letter Circular LC-814 \Supersedes Circular C335 REVISED CLASSIFICATION OF RADIO SUBJECTS USED IN NATIONAL BUREAU OF STANDARDS January 11, 1946 . IBPL=R29 U, Sc DEPARTMENT Of COMMERCE Letter NATIONAL BUREAU Of STANDARDS Gi rcular WASHINGTON LO-glU (Supersedes Circular G 3S5 ) January 11, 19^6 REVISED CLASSIFICATION OF RADIO SUBJECTS USED IN NATIONAL BUREAU OF STANDARDS Cont ent s Page I 0 Introduction . „ . « o . » . * . .. 1 IX. The Dewey Decimal System of Glassification3 ....... 2 III. Ola ssif ication of Radio Subjects ............ 3 IV. Revised Glassification of Radio Subjects U Classification Outline Index RQOO General Radio Material ............. u RlOO Radio Principles . 5 R200 Radio Measurements and Standardisation .... 15 R3GO Radio Apparatus and Equipment ........ 19 RHoo Radio Communication Systems ......... 23 R5OQ Applications of Radio ......... ... S9 1600 Radio Station® § Equipment;, Regulations Design, s Operation, Maintenance and Management . , 32 RJOO Radio Manufacturing and Repairing ...... 33 RSQO Nonradio . 33 V. Subject Index . ...... ...... 37 I . Introductio n The present pamphlet is an expansion and revision of Bureau of Standards Circular G385, "Glassification of Radio Subjects - An Exten- w sion of the Dewey Decimal System p published in 1930. The latter,, in turn, was a revision of the Bureau © Circular C 138 , published in 1923. As indicated in the title of Circular 0385, the classification was an extension of the general Dewey Decimal System, prepared by Doctor Melvin Dewey for classifying books, publications, references, and other materi- al as found in reference and public libraries. The Dewey Glassification at that time did not include a detailed classification for radio, and 5 the Bureau s Circular C 3 S 5 was designed to fill the need of organizations desiring a classification table covering radio science.
  • IOTD250 IOT Amplifier for UHF Television Service

    IOTD250 IOT Amplifier for UHF Television Service

    IOTD250 IOT Amplifier for UHF Television Service FEATURING • Operable as a Digital or Analogue Amplifier. • Output Power Specified as a digital amplifier for corrected average powers up to 13 kW. Rated as a common amplifier from 20 kW peak sync. vision plus 2.0 kW single carrier aural to 33 kW peak sync. vision plus 3.3 kW single carrier aural. Rated as a vision amplifier from 30 to 45 kW. • Frequency Range 470 to 810 MHz (Bands IV and V) in a single tube and circuit. • Simple Tube Exchange Continuously tunable external cavities, with digital frequency indicators. This means that a replacement tube will be coarse tuned on installation, needing only trimming adjustments. • Simple, Efficient Cooling Air-cooled cavities and gun. Water cooled body and collector. • Easy to Tune Input Cavity Input cavity has a single tuning control. • Long Life High reliability electron gun with barium aluminate cathode and pyrolytic graphite grid. • All Ceramics Aluminium Oxide No beryllium oxide hazard. DESCRIPTION IOTD250 is a high efficiency Inductive Output Tube amplifier for use in the output stage of transmitters in UHF television service. The IOT has an electromagnetically focused electron beam which is density bunched using a rugged grid driven by an RF cavity. The IOT beam power varies with the instantaneous output power. The circuit assembly IMD2030 (sold separately) is designed so that the cavities can be detached from the vacuum tube and refitted on a replacement without disturbing the tuning. Therefore the replacement IOT is coarse tuned at switch-on and requires only trimming adjustments. A feature of the cavity design is that tuning of each cavity, including the input cavity, is by means of a single control.
  • The Inductive Output Tube the Latest Generation of Amplifier for Digital Terrestrial Television Transmission

    The Inductive Output Tube the Latest Generation of Amplifier for Digital Terrestrial Television Transmission

    The inductive output tube The latest generation of amplifier for digital terrestrial television transmission R. Heppinstall (EEV Ltd) G.T. Clayworth (EEV Ltd) The inductive output tube (IOT) is the latest generation of amplifying device for use in high-power transmitters. It entered service in 1991 and is now used world-wide as a more efficient replacement for the klystron at UHF. The performance of the IOT in period has been to reduce the cost of ownership of a transmitter whilst in no way compromising the analogue television transmitters is reliability which is the hallmark of the television outlined here. The article also broadcast transmitter. presents and discusses the results of its performance as the final amplifier Three different types of tubes are in general use as in the new generation of digital the final amplifiers in UHF television transmit- terrestrial television transmitters. ters: – tetrodes; – klystrons; – inductive output tubes. 1. Introduction When the UHF television service began, tetrodes The transmission of a terrestrial television service were a natural choice. They were available and at UHF frequencies commenced several decades considerable experience of their use as VHF ago. Since its inception there has been continuous amplifiers had already been obtained. With some improvement in the technology employed – both development they were soon capable of providing in the electron tubes available as the final high- output powers of up to 20 kW at frequencies of up power amplifiers and in the transmitters them- to 860 MHz. However, their gain is low and their Original language: English selves. The principal objective throughout this average lifetime is only up to 15,000 hours.