PORTABLE ROTATING ANODE X-RAY TUBE WITH VERY SMALL FOCUS

A NEW, PORTABLE, WATER-COOLED ROTATING ANODE X-RAY TUBE WILLBE DESIGNED AND BUILT IN A CONFIGURATION PARTICULARLY SUITEDTO THE NEEDS OF THE X-RAY CRYSTALLOGRAPHER: E.G., FOUR USEFUL WINDOWS, A 0- TO 10-DEGREE TAKE-OFF ANGLE, A COPPER TARGET, CONVENIENT SIZE AND WEIGHT, AND REQUIRING ONLY HIGH VOLTAGE, WATER, AND LOW-VOLTAGE LINES TO CONNECT IT TO A REMOTE POWER SUPPLY. THE TUBE IS BAKED OUT AT MANUFACTURE AND SEALED OFF AT VACUUM LEVELS APPRECIABLY LOWER THAN THAT ACHIEVABLE ON ANY EXISTING CRYSTALLOGRAPHIC ROTATING ANODE UNIT. IT USES A COMBINATION OF SPECIAL BEARING CONFIGURATION AND INTEGRAL ION PUMPS TO MAINTAIN THE VACUUM DURING USE. THIS ASSURES IMPROVED SHELF LIFE, FILAMENT LIFE, RELIABILITY, AND PERFORMANCE. SPECIAL ATTENTION WILL BE DIRECTED TOWARD ACHIEVING A VERY SMALL X-RAY SOURCE (0.1 X 0.1 MM PROJECTED) THAT (1) REDUCESTHE SIZE OF THE DIFFRACTED SPOT; (2) PROVIDES INCREASED BRILLIANCE, THEREBY IMPROVING PEAK-TO-BACKGROUND RATIOS; AND (3) PERMITS THE EXAMINATION OF CRYSTALS HAVING LARGER UNIT CELLS. ALL OF THESE ARE EXTREMELY IMPORTANT IN THE STRUCTURE ANALYSIS OF PROTEINS, OF OTHER LARGE MOLECULES, AND OF CRYSTALS THAT ARE EXTREMELY SMALL THEMSELVES. THIS NEW PORTABLE SOURCE WILL OPEN A NEW HORIZON IN THE STUDY OF LIQUIDS.