Browse Prior Art Database

THERMALLY MATCHED RESONANT MICROWAVE CAVITIES

IP.com Disclosure Number: IPCOM000010123D
Publication Date: 2002-Oct-23
Document File: 5 page(s) / 5M

Publishing Venue

The IP.com Prior Art Database

Related People

Bert Egley: AUTHOR

Abstract

A pair of microwave resonators, in which the first resonator has a means for matching the thermal response of the second resonator, such that both resonators can be driven by a common RF power source. The means for matching the thermal response of resonators involves the novel use of at least two metals with different thermal expansion rates, and a probe that is inserted in the first resonator. The likely use of the invention is in a charged particle accelerator that uses a pre-bunching cavity that 15 driven by the same RF power source as the rest of the accelerating structure.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 50% of the total text.

THERMALLY MATCHED RESONANT MICROWAVE CAVITIES

Bert Egley

SIEMENS

SUPPLEMENTAL SHEET FOR INVENTION DISCLOSURE

Our Ref: 2002E12267US

This searchable text file was produced by applying optical character recognition to a scanned document. If an illustration occurs within the scanned document, the effect of applying optical character recognition to that illustration usually produces a series of disarrayed characters.

ABSTRACT

A pair of microwave resonators, in which the first resonator has a means for matching the thermal response of the second resonator, such that both resonators can be driven by a common RF power source. The means for matching the thermal response of resonators involves the novel use of at least two metals with different thermal expansion rates, and a probe that is inserted in the first resonator. The likely use of the invention is in a charged particle accelerator that uses a pre-bunching cavity that 15 driven by the same RF power source as the rest of the accelerating structure.

BACKGROUND INFORMATION

Figure 1 shows a charged particle accelerator containing a pre bunching cavity (resonator #1) and a series of coupled accelerating cavities (resonator #2) The entire accelerator is supplied power from a common RF power source

In order to effectively deliver power and accelerate charged par1icles the frequency of the RF power source must loosely match the frequency of both resonators It IS well know that the frequency of these resonators change with temperature (this is what is meant by 'thermal response' in the abstract) Typically an Automatic Frequency Control (AFC) system will adjust the frequency of the RF power source to match that of resonator #2 If resonator #1 has a different thermal response than resonator #2, It will not be effective at accelerating charged par1lcles

The prior art shows many designs (see 15 cited patents) aimed at making microwave resonant cavities that are Insensitive to temperature Most of these also use two metals With different thermal expansion rates However, these all attempt to produce single cavity resonators whose frequencies don't change with temperature, rather than producing resonators whose thermal response matches that of other resonators Also none of the prior ar1 makes use of a probe, which is also used to feed RF power Into the cavity, as the means for thermal compensation

The graph in figure 2 illustrates the problem that the invention attempts to solve Resonator #2, the primary accelerating structure, IS manufactured from highly pure copper As the copper expands with temperature the volume of the microwave cavities increase, causing their frequency to decrease This frequency change With temperature is approximately linear, typical S-Band accelerating structures will have a slope of about -50 kHzjøC Resonator #1 IS a pre-bunching cavity with a different design than the cavities In resonator #2 It will have a different thermal response, typical S-Band pre-bunching cavities will have a s...