Abstract: An induction coil composed of n pieces of identically shaped coil elements (where n is equal to or greater than two), which are rotation-symmetrically arranged with respect to an axis normal to the surface of an object to be processed, is provided above the object, the coil elements being electrically connected in parallel. Each of the coil elements of the induction coil encircles the aforementioned axis, with the ground end and the feed end located at the same position on a projection plane on the object with the ground end under the feed end. Each coil element has a bottom portion shaped like an arc having a predetermined width and a central angle of 360°/n, with the ground end at one end thereof, and a feed portion shaped like an arc having a predetermined width, with the feed end at one end thereof, the feed portion being located above the bottom portion and electrically connected to the same bottom portion.

Abstract: An induction coil composed of n pieces of identically shaped coil elements (where n is equal to or greater than two), which are rotation-symmetrically arranged with respect to an axis normal to the surface of an object to be processed, is provided above the object, the coil elements being electrically connected in parallel. Each of the coil elements of the induction coil encircles the aforementioned axis, with the ground end and the feed end located at the same position on a projection plane on the object with the ground end under the feed end. Each coil element has a bottom portion shaped like an arc having a predetermined width and a central angle of 360°/n, with the ground end at one end thereof, and a feed portion shaped like an arc having a predetermined width, with the feed end at one end thereof, the feed portion being located above the bottom portion and electrically connected to the same bottom portion.

Abstract: A distributed file system in which the cache hit ratio of a client is enhanced to speed up a file access for each of users logging into the client. A file server includes an access frequency database in which the names of users are listed in association with the names of files that are frequently accessed by the individual users. Each client includes a log-in user table for entering the name of a user who is logging in, and a cache priority control module. The cache priority control module sets priority levels for the copies of the files stored in a cache area, on the basis of the contents of the access frequency database and the log-in user table. The set priority levels function as criteria when any of the file copies is to be expelled from the cache area. Owing to this construction, the copies of the files of high usage frequencies are preferentially kept in the cache area of the client for each user logging into this client, whereby the cache hit ratio can be enhanced to speed up the file access.