EUROPEAN SITE REPORTS

Site: AEG
Microwave and High Voltage Devices Subdivision
Soflinger Strasse 100
D-7900 ULM (Donau)
Germany

Date Visited: June 24, 1992

Report Author: E. Miller

ATTENDEES

NASA/NSF:

E. Miller

HOSTS:

Dr. Andreas Peters

Hartmut Radlinger

Peter Janker

Johannes Hecht

BACKGROUND

AEG is part of the Daimler-Benz Group, discussed in greater detail in the Background section of the MBB Deutsche Aerospace site visit report.

The AEG Microelectronics, Opto & Vacuum Electronics (O&VE) organization contains the Microwave and High Voltage Devices (MW & HVD) subdivision, which was the subject of this site visit. O&VE has about 1,500 employees, with a budget of about 250 million DM/yr. The MW & HVD subdivision has about 500 employees and a budget of about 110 million DM/yr. Its products include tubes for radar, electronic counter measure (ECM) equipment, earth stations and satellites. Their intention is to make their own line of travelling wave tubes amplifiers (TWTAs) for satellites.

World-wide, three major space tube manufacturers remain: AEG MW & HVD, Hughes Electronic Tube Division, and Thomson CSF Tubes Electroniques.

RESEARCH AND DEVELOPMENT ACTIVITIES

TWTs for Space Use

AEG has a long history in TWTs for space applications, beginning with tubes for the SYMPHONIE satellite in 1974. There are 385 TWTs built by AEG in orbit. Success is based on techniques and proprietary methods for building tubes well. "All competing companies have access to the same basic technologies. Each can apply certain technologies better than the others." AEG's achievements are shown in Table AEG.1.

Table AEG.1
AEG Achievements

Techniques Used

Techniques employed in recent TWTs include:

1. Multistage Depressed Collector - up to five stages, with magnetic focussing, anti-symmetric design, and potential-free collector for better heat dissipation.
2. Double Comb Delay Line - for tubes with higher power than is achievable with helix tubes. AEG is the only manufacturer producing tubes with this feature.
3. In-House, Unique, Analysis Software - special software used for tube design.
4. In-House Manufacture of Cathodes - these mixed metal cathodes "have 500 k hour " No build failures due to cathode in last 2 1/2 years." They have 1 amp/cm(superscript 2) loading. Heater power has been reduced from 3 W to 2 W.
5. Improved Taper Designs - these designs improve circuit efficiency. Over the years the step taper design led to the soft taper which led to the HELOS concept which produces linear phase.

Future Improvements

Future improvements anticipated include:

1. design of improved collectors
2. removal of harmonics
3. better magnetic and electrostatic lenses
4. minimization of conductor losses through appropriate use of copper, better plating, and improved heat transfer
5. reduction of secondary emission
6. reduction of backstreaming electrons

TWT developments at AEG are mostly internally funded. There is some European Space Agency (ESA) and German government funding.

SUMMARY

AEG is one of three major space tube builders in the world. They are current in their use of technology and have success that results from experience, care, and just doing things well. It is their intention to supply not only TWTs but TWTAs as well in the future.

Multi-stage depressed collectors are used to increase efficiency. Double comb delay lines are used for higher power tubes. Cathode life problem has been solved with mixed metal cathodes "having 500 k hour life." Improved taper designs improve circuit efficiency.