DESIGN AND TESTING OF A MULTI-OUTPUT 300kV PROTOTYPE INDUCTION CELL PULSED POWER SUPPLY FOR DARHT

Technology demonstrations of key components at LANL for the Dual-Axis Radiographic Hydro Test (DARHT) Facility including the turnkey Induction Cell Pulsed Power Supply (ICPPS) delivered by Maxwell have been in progress at the DARHT Integrated Test Stand (ITS) for over three years. The prototype system has accumulated >35,000 shots to date with no component failures and only minor system malfunctions. The eight induction cells in the ITS are driven by four water insulated Blumleins at 250 kV nominal, >67 ns wide negative polarity pulses with ±1% flat-top deviation. Each Blumlein drives two cells and is switched by an, SF6 insulated, coaxial triggered spark gap. The Blumlein is charged using a pulse transformer via. two electrically isolated primary capacitors switched by their respective thyratrons. The timing adjustment between the respective Blumlein output pulses is controlled via Maxwell's turnkey DARHT HV Triggering System [1]. Four switching supplies provide independent control of each Blumlein output pulse voltage. The ICPPS prototype system is provided with a single integrated control console capable of remote operation via a MODICON programmable logic controller. Details of the ICPPS and the results obtained during this extensive testing are described. INTRODUCTION The tum-key system consists of four independent high voltage pulse forming sections. Each section, as shown in Figure 1, consists of a Blumlein and a charging unit (BCU) enclosure. All ancillary equipment associated with each BCU is located in a shielded enclosure outside the respective oil tank enclosure. The pulse voltage is injected into four cables (surge impedance 50 Q each) at each Blumlein output. The controls for the BCUs and the four Maxwell CCDS high voltage switching power supplies (35 kV, 2 kJ/s) are located in two side-by-side 19 inch rack mount cabinets approximately 6 feet high, as shown in Figure 2. The control system is capable of selecting and operating any combination of the four BCUs located up to 100 feet away. Independent operation and monitoring of each of the four BCU/Blumlein can be performed either in the LOCAL mode from the control console front panels, or in the REMOTE mode via a MODICON programmable logic controller which interfaces to the ICPPS control system. Each BCU oil enclosure assembly, shown in Figure 3, is 24 inches wide x 43 inches long x 41 inches deep. The BCUs utilize two independent 1.2 !-LF, 40 kV, capacitors which are discharged via two independent hollow anode glass thyratrons into two electrically isolated primary windings of a 1: 11 step-up pulse transformer. This inverting pulse transformer charges the Blumlein intermediate conductor positively in -4.5 !lS. The spark gap is triggered close to the peak of the charge voltage waveform. When triggered the Blumlein injects a negative polarity pulse into the four matched output cables, each -45 feet long. Protection is provided for thyratron filament heater out-of-range voltage. A separate protection circuit monitors the pulse transformer reset current. The controls are provided with diagnostic circuits to detect a thyratron pre-fire condition. Furthermore, a thyratron overcurrent protection circuit is included to prevent operation if currents in excess of the thyratron rating are detected. The control system automatically disables and discharges the capacitors when a thyratron or the pulse transformer reset fault condition is detected. All interlocks are of the latching type and if breached are indicated both visually on the control console and relayed to REMOTE via a corresponding set of isolated relay contacts. Each BCU enclosure is equipped with a single Pearson 110A current monitor to record the total primary (2 circuits) discharge current waveshape. Two independent resistive voltage dividers monitor the voltage pulse applied to the primary windings. The pulse transformer secondary voltage is, again, monitored via a resistive 1412 Report Documentation Page Form Approved OMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE JUL 1995 2. REPORT TYPE N/A 3. DATES COVERED 4. TITLE AND SUBTITLE Design And Testing Of A Multi-Output 300kv Prototype Induction Cell Pulsed Power Supply For Darht 5a. CONTRACT NUMBER