Development of an X-band magnicon amplifier for the Next Linear Collider -- Cold cathode experiments and a thermionic design study

Conference · Mon Dec 30 23:00:00 EST 1996

OSTI ID:445555

Gold, S H; Fliflet, A W ^[1]; Hafizi, B ^[2]; Kinkead, A K ^[3]; Nezhevenko, O A; Yakovlev, V P ^[4]; True, R B ^[5]

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1. Naval Research Lab., Washington, DC (United States). Plasma Physics Div.
2. Icarus Research, Bethesda, MD (United States)
3. SFA, Landover, MD (United States)
4. Budker Inst. of Nuclear Physics, Novosibirsk (Russian Federation)
5. Litton Systems, Inc., San Carlos, CA (United States). Electron Devices Div.

The Naval Research Laboratory has been studying the operation of an 11 GHz frequency-doubling magnicon amplifier driven by a {approximately}650 kV, 225 A, 5.5-mm-diam. electron beam produced by a velvet cathode driven by a single-shot Marx generator. Recent experiments using a heterodyne diagnostic have demonstrated emission at 11.12 GHz, the predicted magnicon output frequency, in a 200 nsec pulse when the first cavity is driven at 5.56 GHz. Under these conditions, the experiment produced {approximately} 15 MW at {approximately} 10% efficiency. Simulations suggest that this low efficiency is due to operation in a regime in which all of the spin up occurs in the penultimate deflection cavity, and also to the large beam diameter. Based on these results, it became evident that the NRL program must transition to a thermionic electron gun, a rep-rated modulator, and an ultrahigh vacuum environment in order to demonstrate the feasibility of an efficient, long-pulse, high-duty-factor magnicon amplifier at 11.4 GHz for linear accelerator applications. The authors have designed a new thermionic magnicon experiment, incorporating an advanced high-convergence electron gun to produce a 500 kV, 200 A, 2-mm-diam. electron beam, an improved deflection cavity design, and an improved output cavity that employs side-coupling to extract the rf power through a pair of X-band waveguides separated by 135{degree} around the azimuth of the cavity without destroying the symmetry of the rotating quadrupole mode. The predicted efficiency is {approximately} 60%.

• Sponsoring Organization: USDOE, Washington, DC (United States); Department of the Navy, Washington, DC (United States)
• OSTI ID: 445555
• Report Number(s): CONF-960634--
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
DESIGN
ELECTRON GUNS
LINEAR COLLIDERS
MICROWAVE AMPLIFIERS
PERFORMANCE
THERMIONIC EMISSION