Materials test chamber with xenon lamp radiation

An accelerated weathering apparatus comprising:

• a test chamber having a support member to support a specimen which is to be tested;
• a lamp for producing light in the test chamber;
• a high instantaneous, low average current ballast for controlling operation of the lamp wherein the ballast generates current pulses, at least some of the current pulses being at least 100 amps;
• and
• dimming circuitry designed to limit energy transfer from the capacitor into the lamp.

A method of operating a high instantaneous, low average current ballast which controls a xenon lamp, said method comprising the steps of:

• generating a high DC voltage to charge a capacitor to a desired level;
• connecting the charged capacitor to the xenon lamp, through a switch;
• firing a starting transformer which generates a voltage field at the xenon lamp, thereby ionizing gases in the xenon lamp;
• forming a main current path including the charged capacitor, the switch, and the xenon lamp, said switch being disposed between and in series with the charged capacitor and the xenon lamp;
• delivering current to the xenon lamp through the main current path;
• and
• opening the switch so that the capacitor is again disconnected from the xenon lamp and charged up to the desired value.

A method of operating a high instantaneous, low average current ballast which controls a xenon lamp, said method comprising the steps of:

• generating a high DC voltage to charge a capacitor to a desired level;
• connecting the charged capacitor to the xenon lamp, through a switch;
• firing a starting transformer which generates a voltage field at the xenon lamp, thereby ionizing gases in the xenon lamp;
• forming a current path including the charged capacitor, the switch, and the xenon lamp;
• delivering current to the xenon lamp through the current path;
• opening the switch so that the capacitor is again charged up to the desired value;
• using dimming circuitry, limiting energy transfer from the capacitor into the lamp.

An accelerated weathering apparatus comprising:

• a specimen chamber configured to hold a specimen;
• a xenon lamp;
• a high-instantaneous, low-average current ballast configured to run the xenon lamp including,
• a front end, that produces a high DC voltage,
• an arc capacitor designed to store energy and release the energy into the xenon lamp as short, high current pulses,
• a starting transformer which generates a high voltage which facilitates striking an arc in the xenon lamp,
• a switch located between the arc capacitor and the xenon lamp, wherein when the switch is in an on state, a high current pulse is generated from the energy on the arc capacitor, and is delivered to the xenon lamp, and when the switch is in an off state, current flow is blocked thereby allowing a build-up of the arc capacitor energy, without leakage to the xenon lamp,
• a dimmer configured to limit the energy being supplied from the arc capacitor,
• thereby controlling light output of the xenon lamp;
• an irradiance sensor, which measures the amount of light in the specimen chamber;
• and
• an irradiance controller, which receives signals from the irradiance sensor, and adjusts a dimmer in accordance with the received signals, in order to maintain a preselected output from the xenon lamp.

A current ballast which controls a xenon lamp, said ballast comprising:

• a front end, supplied by an external power source, which generates high DC voltage;
• an arc capacitor connected to store energy developed from charging action of the front end and to selectively release the arc capacitor energy in the lamp as current pulses, at least some of the current pulses being at least 100 amps at a rate of at least 60 per second, wherein the current pulses average less than 20 amps over a full signal;
• a starting transformer that generates a voltage used to ionize gas in the lamp to strike an arc;
• a switch connected between the arc capacitor and the lamp used to control generation of the current pulses;
• and
• an internal or external timer to control the switch and transformer for selectively generating and supplying of the current pulses to the lamp.

A method of operating a current ballast which controls a xenon lamp, the method comprising the steps of:

• generating a high DC voltage to charge a capacitor to a desired level;
• connecting the charged capacitor to the xenon lamp through a switch;
• forming a current path including the charged capacitor, the switch, and the xenon lamp;
• delivering current pulses, at least some of the current pulses being at least 100 amps to the xenon lamp through the current path, said current pulses having a full signal average of less than 20 amps.