Synchrotron Radiation Gwyn P. Williams
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Synchrotron Radiation
Gwyn P. Williams National Synchrotron Light Source, Brookhaven National Laboratory
20
21
Synchrotron Radiation
Gwyn P. Williams National Synchrotron Light Source, Brookhaven National Laboratory Today synchrotron radiation is used for a number of applications. The Na tional Synchrotron Light Source at Brookhaven National Laboratory (BNL) serves the needs of a large spectrum of university and industrial users. The range of applications covers such diverse subjects as catalysis and corrosion. Here I'll concentrate on x-ray lithography, which is an especially interesting ap plication. A fascinating sidelight of this application is the production of com mercial accelerators for x-ray lithography. Synchrotron radiation is synonymous with x-rays. From the initial invention of the x-ray tube in 1896 until about 1960, the brightness (the log of brilliance in Fig. 1) didn't change very much. About that time rotating anode tubes ap peared. Then, starting in the Sixties, synchrotron radiation facilities began pop ping up. They appeared at Madison and Stanford and at various places in Europe, including England, where I became involved about 20 years ago. Soon, these accelerator x-ray sources produced dramatic increases in the x-ray bright ness until they are now a trillion times brighter than a conventional x-ray machine. When a charged particle accelerates it radiates photons or x-rays. For example, in a conventional x-ray tube the electron beam accelerates from a fila ment to an anode, where it decelerates rapidly at the anode and emits x-rays (shown schematically in Fig. 2). A different approach is to accelerate (or decelerate) the particle by passing it through a magnetic field. This is what really happens in an accelerator. When the particles curve in the magnetic field, x-rays are emitted. These x-rays are very collimated. The effective source is very small because the electrons can be focused down. There's also no heating
Synchrotron Radiation
Gwyn P. Williams National Synchrotron Light Source, Brookhaven National Laboratory
20
21
Synchrotron Radiation
Gwyn P. Williams National Synchrotron Light Source, Brookhaven National Laboratory Today synchrotron radiation is used for a number of applications. The Na tional Synchrotron Light Source at Brookhaven National Laboratory (BNL) serves the needs of a large spectrum of university and industrial users. The range of applications covers such diverse subjects as catalysis and corrosion. Here I'll concentrate on x-ray lithography, which is an especially interesting ap plication. A fascinating sidelight of this application is the production of com mercial accelerators for x-ray lithography. Synchrotron radiation is synonymous with x-rays. From the initial invention of the x-ray tube in 1896 until about 1960, the brightness (the log of brilliance in Fig. 1) didn't change very much. About that time rotating anode tubes ap peared. Then, starting in the Sixties, synchrotron radiation facilities began pop ping up. They appeared at Madison and Stanford and at various places in Europe, including England, where I became involved about 20 years ago. Soon, these accelerator x-ray sources produced dramatic increases in the x-ray bright ness until they are now a trillion times brighter than a conventional x-ray machine. When a charged particle accelerates it radiates photons or x-rays. For example, in a conventional x-ray tube the electron beam accelerates from a fila ment to an anode, where it decelerates rapidly at the anode and emits x-rays (shown schematically in Fig. 2). A different approach is to accelerate (or decelerate) the particle by passing it through a magnetic field. This is what really happens in an accelerator. When the particles curve in the magnetic field, x-rays are emitted. These x-rays are very collimated. The effective source is very small because the electrons can be focused down. There's also no heating