PAGE CONTENTS
Objectives
As manufacturer of Travelling Wave Tubes (TWT) THALES Electron Devices (TED) started the low-frequency TWT development for space applications (1GHz to 3GHz) in 1996 to re-enter this market. Within the commercial programs with their very tight production schedule only limited room remained for more peripheral improvement efforts.
With the project ‘L- and S-Band Travelling Wave Tubes’ TEDG realized in a project together with ESA (ESTEC) the improvement of the existing tube designs and the extension of the portfolio in the S-Band and also in the L-Band. Depending on the output power range, conduction cooled and radiation cooled versions are now available.
The present project is the last part (Step 3 and 4) of the development program dealing with L-band medium and high power class as well with S-band low to medium output power. Both steps were started at the end of 2003 by ESTEC and THALES Electron Devices (TED) and were finished successfully by the end of 2006.
The starting point for Step 3 of the project was the development of improved 150W L-band TWTs based on the first TED L-band design TL 2140 which is successfully in orbit for several years now. The challenge was to improve the efficiency by 7% over a frequency bandwidth of 200MHz and to reduce the mass by 400g. In addition the portfolio in the L-band was extended to a radiation cooled design and to the 250W output power class (conduction cooled only) with comparable electrical performance and mass.
In Step 4 the excellent results for electrical performance in the S-band high power class (Step 1 and Step 2) were transferred to the medium output power classes with up to 180 W in conduction and radiation cooled design.
These topics were a big success for TED to define an improved generation of Travelling Wave Tubes (TWT) with more than 61% in efficiency for L-band and 63% for S-band.
Each of the Steps was divided into three phases:
- Theoretica
Challenges
The goal for the electrical performance are:
- L-band TWT: 1.45GHz to 1.65GHz
- Output power: 150W class and 250W class
- Efficiency: > 61%
- Gain: > 42dB
- Mass: < 2200g for conduction cooled, RC TBD
- L-band TWT: 2.45GHz to 2.65GHz
- Output power: 70W to 180W
- Efficiency: > 62%
- Gain: > 49dB for 90W class
> 34dB for 150W class - Mass: < 1400g
Plan
Starting points of the development were the existing tubes for both frequency classes and the results of Step 1 and 2 of the project. The first action was the theoretical examination of the existing materials, dimensions and design by the help of suitable development tools. Then the theoretical results were tested on subassembly level to verify the basic data and finally on Bread Boards to fulfil the requirements.
After the verification the theory was transferred to the new power classes – again with the computer simulations. Finally the housing for conduction and radiation cooled versions were designed.
After being tested electrically the tubes were subjected to qualification tests concerning electrical performance, mechanical and thermal design and environmental conditions. The individual temperature limits were investigated during TV testing. All designs passed the qualification tests successfully.
Current Status
The project was successfully finished.